Science.gov

Sample records for absorbs ultraviolet light

  1. Novel Ultraviolet Light Absorbing Polymers For Optical Applications

    NASA Astrophysics Data System (ADS)

    Doddi, Namassivaya; Yamada, Akira; Dunks, Gary B.

    1988-07-01

    Ultraviolet light absorbing monomers have been developed that can be copolymerized with acrylates. The composition of the resultant stable copolymers can be adjusted to totally block the transmission of light below about 430 nm. Fabrication of lenses from the materials is accomplished by lathe cutting and injection molding procedures. These ultraviolet light absorbing materials are non-mutagenic and non-toxic and are currently being used in intraocular lenses.

  2. Bacteriocin typing by leakage of ultraviolet light-absorbing material.

    PubMed Central

    Farkas-Himsley, H; Pagel, A

    1977-01-01

    A rapid and reproducible method of bacteriocin typing is described based on leakage of ultraviolet light-absorbing material (UVAM), detectable in supernatants of bacteriocin-sensitive cultures, by means of a spectrophotometer. The prerequisites for reproducible results, with nonsignificant fluctuations in standard error of the mean, are: a set of standardized bacteriocins, produced under defined conditions and of determined strength. These must interact with the unknown bacterial culture in suspension and at a given ratio in order to achieve an optimal multiplicity of interaction. Pyocin and colicin typing by the "scrape and streak" technique of Gillies (J. Hyg. 62:1-10, 1963) was compared with the UVAM leakage method in 275 tests; the two tests were found to be in good agreement for the strains tested. PMID:406200

  3. Ultraviolet light absorbers having two different chromophors in the same molecule

    DOEpatents

    Vogl, O.; Li, S.

    1983-10-06

    This invention relates to novel ultraviolet light absorbers having two chromophors in the same molecule, and more particularly to benzotriazole substituted dihydroxybenzophenones and acetophenones. More particularly, this invention relates to 3,5-(di(2H-benzotriazole-2-yl))-2,4-dihydroxybenzophenone and 3,5-(di(2H-benzotriazole-2-yl))-2,4-dihydroxyacetophenone which are particularly useful as an ultraviolet light absorbers.

  4. Ultraviolet light absorbers having two different chromophors in the same molecule

    DOEpatents

    Vogl, Otto; Li, Shanjun

    1988-05-17

    Ultraviolet light absorbing compounds having two different chromophors in the same molecule, particularly the benzotriazole chromophor and either the dihydroxybenzophenone or dihydroxyacetophenone chromophor; specifically, the two compounds 3,5-[di(2H-benzotriazole-2-yl)]-2,4-dihydroxyacetophenone and 3,5-[di(2H-benzotriazole-2-yl)]2,4-dihydroxybenzophenone.

  5. Removal of fluorescence and ultraviolet absorbance of dissolved organic matter in reclaimed water by solar light.

    PubMed

    Wu, Qianyuan; Li, Chao; Wang, Wenlong; He, Tao; Hu, Hongying; Du, Ye; Wang, Ting

    2016-05-01

    Storing reclaimed water in lakes is a widely used method of accommodating changes in the consumption of reclaimed water during wastewater reclamation and reuse. Solar light serves as an important function in degrading pollutants during storage, and its effect on dissolved organic matter (DOM) was investigated in this study. Solar light significantly decreased the UV254 absorbance and fluorescence (FLU) intensity of reclaimed water. However, its effect on the dissolved organic carbon (DOC) value of reclaimed water was very limited. The decrease in the UV254 absorbance intensity and FLU excitation-emission matrix regional integration volume (FLU volume) of reclaimed water during solar light irradiation was fit with pseudo-first order reaction kinetics. The decrease of UV254 absorbance was much slower than that of the FLU volume. Ultraviolet light in solar light had a key role in decreasing the UV254 absorbance and FLU intensity during solar light irradiation. The light fluence-based removal kinetic constants of the UV254 and FLU intensity were independent of light intensity. The peaks of the UV254 absorbance and FLU intensity with an apparent molecular weight (AMW) of 100Da to 2000Da decreased after solar irradiation, whereas the DOC value of the major peaks did not significantly change.

  6. Ultraviolet and Light Absorption Spectrometry.

    ERIC Educational Resources Information Center

    Hargis, L. G.; Howell, J. A.

    1984-01-01

    Reviews developments in ultraviolet and light absorption spectrometry from December 1981 through November 1983, focusing on the chemistry involved in developing suitable reagents, absorbing systems, and methods of determination, and on physical aspects of the procedures. Includes lists of spectrophotometric methods for metals, non-metals, and…

  7. Dichroic ultraviolet light filters

    NASA Astrophysics Data System (ADS)

    Kocher, Christoph; Weder, Christoph; Smith, Paul

    2003-10-01

    With the intention to produce dichroic filters for use in photoluminescent systems that rely on polarized UV light, we synthesized a number of linear, dichroic dyes, which absorb mainly in the near-UV range of the electromagnetic spectrum. These dyes were designed for compatibility with common thermoplastic polymers such as linear low-density poly(ethylene), poly(ethylene terephthalate), and polyamide-12. Films of these host polymers that consisted of 0.2% by weight of various dichroic UV dyes were produced by common melt-processing schemes. Uniaxial drawing of these films yielded highly dichroic UV filters with dichroic ratios in absorption that in some cases exceeded 100. The fact that these free-standing films display little or no coloration and are environmentally stable makes them useful for various applications that involve generation of polarized UV light.

  8. [Decoloring and spectral properties analysis of innoxious ultraviolet absorbents].

    PubMed

    Fang, Yi-Wen; Ni, Wen-Xiu; Huang, Chong; Xue, Liang; Yu, Lin

    2006-07-01

    The ultraviolet absorbent extracted from mango leaves, was discolored by some decoloring agent. Then the spectral properties of the discolored ultraviolet absorbents were analyzed. The discolored method of ultraviolet absorbent was studied by comparing one with the others. The results showed that the discoloring effect was satisfactory by using active carbon, H2O2, citric acid, and oxalic acid as decoloring agent. Specially, when oxalic acid was used as decoloring agent, the color of the production was slight, the rate of production was high, and the absorption effect of ultraviolet ray was well. When the concentration of the ultraviolet absorbent solution is 0.5% (w/w), the ultraviolet ray transmission was smaller than 0.3% in 200-370 nm, and it increased slightly from 370 nm. There was a maximum value at 400 nm, approaching 12%.

  9. Light, Including Ultraviolet

    PubMed Central

    Maverakis, Emanual; Miyamura, Yoshinori; Bowen, Michael P.; Correa, Genevieve; Ono, Yoko; Goodarzi, Heidi

    2009-01-01

    Ultraviolet (UV) light is intricately linked to the functional status of the cutaneous immune system. In susceptible individuals, UV radiation can ignite pathogenic inflammatory pathways leading to allergy or autoimmunity. In others, this same UV radiation can be used as a phototherapy to suppress pathogenic cutaneous immune responses. These vastly different properties are a direct result of UV light’s ability to ionize molecules in the skin and thereby chemically alter them. Sometimes these UV-induced chemical reactions are essential, the formation of pre-vitamin D3 from 7-dehydrocholesterol, for example. In other instances they can be potentially detrimental. UV radiation can ionize a cell’s DNA causing adjacent pyrimidine bases to chemically bond to each other. To prevent malignant transformation, a cell may respond to this UV-induced DNA damage by undergoing apoptosis. Although this pathway prevents skin cancer it also has the potential of inducing or exacerbating autoreactive immune responses by exposing the cell’s nuclear antigens. Ultaviolet-induced chemical reactions can activate the immune system by a variety of other mechanisms as well. In response to UV irradiation keratinocytes secrete cytokines and chemokines, which activate and recruit leukocytes to the skin. In some individuals UV-induced chemical reactions can synthesize novel antigens resulting in a photoallergy. Alternatively, photosensitizing molecules can damage cells by initiating sunburn-like phototoxic reactions. Herein we review all types of UV-induced skin reactions, especially those involving the immune system. PMID:20018479

  10. Damage tolerant light absorbing material

    DOEpatents

    Lauf, R.J.; Hamby, C. Jr.; Akerman, M.A.; Seals, R.D.

    1993-09-07

    A light absorbing article comprised of a composite of carbon-bonded carbon fibers, is prepared by: blending carbon fibers with a carbonizable organic powder to form a mixture; dispersing the mixture into an aqueous slurry; vacuum molding the aqueous slurry to form a green article; drying and curing the green article to form a cured article; and, carbonizing the cured article at a temperature of at least about 1000 C to form a carbon-bonded carbon fiber light absorbing composite article having a bulk density less than 1 g/cm[sup 3]. 9 figures.

  11. Damage tolerant light absorbing material

    DOEpatents

    Lauf, Robert J.; Hamby, Jr., Clyde; Akerman, M. Alfred; Seals, Roland D.

    1993-01-01

    A light absorbing article comprised of a composite of carbon-bonded carbon fibers, prepared by: blending carbon fibers with a carbonizable organic powder to form a mixture; dispersing the mixture into an aqueous slurry; vacuum molding the aqueous slurry to form a green article; drying and curing the green article to form a cured article; and, carbonizing the cured article at a temperature of at least about 1000.degree. C. to form a carbon-bonded carbon fiber light absorbing composite article having a bulk density less than 1 g/cm.sup.3.

  12. Ultraviolet light and ocular diseases.

    PubMed

    Yam, Jason C S; Kwok, Alvin K H

    2014-04-01

    The objective of this study is to review the association between ultraviolet (UV) light and ocular diseases. The data are sourced from the literature search of Medline up to Nov 2012, and the extracted data from original articles, review papers, and book chapters were reviewed. There is a strong evidence that ultraviolet radiation (UVR) exposure is associated with the formation of eyelid malignancies [basal cell carcinoma (BCC) and squamous cell carcinoma (SCC)], photokeratitis, climatic droplet keratopathy (CDK), pterygium, and cortical cataract. However, the evidence of the association between UV exposure and development of pinguecula, nuclear and posterior subcapsular cataract, ocular surface squamous neoplasia (OSSN), and ocular melanoma remained limited. There is insufficient evidence to determine whether age-related macular degeneration (AMD) is related to UV exposure. It is now suggested that AMD is probably related to visible radiation especially blue light, rather than UV exposure. From the results, it was concluded that eyelid malignancies (BCC and SCC), photokeratitis, CDK, pterygium, and cortical cataract are strongly associated with UVR exposure. Evidence of the association between UV exposure and development of pinguecula, nuclear and posterior subcapsular cataract, OSSN, and ocular melanoma remained limited. There is insufficient evidence to determine whether AMD is related to UV exposure. Simple behaviural changes, appropriate clothing, wearing hats, and UV blocking spectacles, sunglasses or contact lens are effective measures for UV protection.

  13. Light-absorbing impurities in Arctic snow

    NASA Astrophysics Data System (ADS)

    Doherty, S. J.; Warren, S. G.; Grenfell, T. C.; Clarke, A. D.; Brandt, R. E.

    2010-12-01

    Absorption of radiation by ice is extremely weak at visible and near-ultraviolet wavelengths, so small amounts of light-absorbing impurities in snow can dominate the absorption of solar radiation at these wavelengths, reducing the albedo relative to that of pure snow, contributing to the surface energy budget and leading to earlier snowmelt. In this study Arctic snow is surveyed for its content of light-absorbing impurities, expanding and updating the 1983-1984 survey of Clarke and Noone. Samples were collected in Alaska, Canada, Greenland, Svalbard, Norway, Russia, and the Arctic Ocean during 1998 and 2005-2009, on tundra, glaciers, ice caps, sea ice, frozen lakes, and in boreal forests. Snow was collected mostly in spring, when the entire winter snowpack is accessible for sampling. Sampling was carried out in summer on the Greenland Ice Sheet and on the Arctic Ocean, of melting glacier snow and sea ice as well as cold snow. About 1200 snow samples have been analyzed for this study. The snow is melted and filtered; the filters are analyzed in a specially designed spectrophotometer system to infer the concentration of black carbon (BC), the fraction of absorption due to non-BC light-absorbing constituents and the absorption Ångstrom exponent of all particles. This is done using BC calibration standards having a mass absorption efficiency of 6.0 m2 g-1 at 550 nm and by making an assumption that the absorption Angstrom exponent for BC is 1.0 and for non-BC light-absorbing aerosol is 5.0. The reduction of snow albedo is primarily due to BC, but other impurities, principally brown (organic) carbon, are typically responsible for ~40% of the visible and ultraviolet absorption. The meltwater from selected snow samples was saved for chemical analysis to identify sources of the impurities. Median BC amounts in surface snow are as follows (nanograms of carbon per gram of snow): Greenland 3, Arctic Ocean snow 7, melting sea ice 8, Arctic Canada 8, subarctic Canada 14

  14. Ultraviolet light and hyperpigmentation in healing wounds

    SciTech Connect

    Wiemer, D.R.; Spira, M.

    1983-10-01

    The concept of permanent hyperpigmentation in wounds following ultraviolet light exposure during the postoperative period has found a place in plastic surgical literature but has not been documented. This study evaluates the effect of ultraviolet light on healing wounds in paraplegics. It failed to confirm permanent alteration in pigmentation response to ultraviolet exposure and suggests that other factors are of greater importance in the development of hyperpigmentation in the healing wound.

  15. Ultraviolet light-an FDA approved technology

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Ultraviolet Light (254 nm) is a U.S. Food and Drug Administration approved nonthermal intervention technology that can be used for decontamination of food and food contact surfaces. Ultraviolet light is a green technology that leaves no chemical residues. Results from our laboratory indicate that ex...

  16. Light-absorbing impurities in Arctic snow

    NASA Astrophysics Data System (ADS)

    Doherty, S. J.; Warren, S. G.; Grenfell, T. C.; Clarke, A. D.; Brandt, R. E.

    2010-08-01

    Absorption of radiation by ice is extremely weak at visible and near-ultraviolet wavelengths, so small amounts of light-absorbing impurities in snow can dominate the absorption of solar radiation at these wavelengths, reducing the albedo relative to that of pure snow, contributing to the surface energy budget and leading to earlier snowmelt. In this study Arctic snow is surveyed for its content of light-absorbing impurities, expanding and updating the 1983-1984 survey of Clarke and Noone. Samples were collected in Alaska, Canada, Greenland, Svalbard, Norway, Russia, and the Arctic Ocean during 2005-2009, on tundra, glaciers, ice caps, sea ice, frozen lakes, and in boreal forests. Snow was collected mostly in spring, when the entire winter snowpack is accessible for sampling. Sampling was carried out in summer on the Greenland ice sheet and on the Arctic Ocean, of melting glacier snow and sea ice as well as cold snow. About 1200 snow samples have been analyzed for this study. The snow is melted and filtered; the filters are analyzed in a specially designed spectrophotometer system to infer the concentration of black carbon (BC), the fraction of absorption due to non-BC light-absorbing constituents and the absorption Ångstrom exponent of all particles. The reduction of snow albedo is primarily due to BC, but other impurities, principally brown (organic) carbon, are typically responsible for ~40% of the visible and ultraviolet absorption. The meltwater from selected snow samples was saved for chemical analysis to identify sources of the impurities. Median BC amounts in surface snow are as follows (nanograms of carbon per gram of snow): Greenland 3, Arctic Ocean snow 7, melting sea ice 8, Arctic Canada 8, Subarctic Canada 14, Svalbard 13, Northern Norway 21, Western Arctic Russia 26, Northeastern Siberia 17. Concentrations are more variable in the European Arctic than in Arctic Canada or the Arctic Ocean, probably because of the proximity to BC sources. Individual

  17. 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.

  18. Ultraviolet Light and Skin Cancer in Athletes

    PubMed Central

    Harrison, Shannon C.; Bergfeld, Wilma F.

    2009-01-01

    The incidence of melanoma and nonmelanoma skin cancers is increasing worldwide. Ultraviolet light exposure is the most important risk factor for cutaneous melanoma and nonmelanoma skin cancers. Nonmelanoma skin cancer includes basal cell carcinoma and squamous cell carcinoma. Constitutive skin color and genetic factors, as well as immunological factors, play a role in the development of skin cancer. Ultraviolet light also causes sunburn and photoaging damage to the skin. PMID:23015891

  19. 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

  20. Characterisation of ultraviolet-absorbing recalcitrant organics in landfill leachate for treatment process optimisation.

    PubMed

    Keen, Olya S

    2017-03-01

    Organics in leachate from municipal solid waste landfills are notoriously difficult to treat by biological processes. These organics have high ultraviolet absorbance and can interfere with the ultraviolet disinfection process at the wastewater treatment plant that receives leachate if the leachate flow contribution is large enough. With more wastewater treatment plants switching to ultraviolet disinfection, landfills face increased pressure to treat leachate further. This study used size exclusion chromatography, fluorescence spectroscopy and ultraviolet/Vis spectrophotometry to characterise the bulk organic matter in raw landfill leachate and the biorecalcitrant organic matter in biologically treated leachate from the same site. The results indicate that biorecalcitrant organics have the polyphenolic absorbance peak at 280 nm, fluorescence peak at 280 nm excitation and 315 nm emission, and molecular size range of 1000-7000 Da, all of which are consistent with lignin. The lignin-like nature of biorecalcitrant leachate organics is supported by the fact that 30%-50% of municipal solid waste consists of plant debris and paper products. These findings shed light on the nature of biorecalcitrant organics in leachate and will be useful for the design of leachate treatment processes and further research on leachate treatment methods.

  1. [Estrogenic activity of ultraviolet absorbers and the related compounds].

    PubMed

    Matsumoto, Hisashi; Adachi, Shinichi; Suzuki, Yasuhiko

    2005-08-01

    The estrogenic activities of ultraviolet absorbers and their related compounds were investigated using MCF-7 cell proliferation assay. Nine of 33 chemicals (benzophenone, 2,4-dihydroxybenzophenone, 2,2',4,4'-tetrahydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2,2'-dihydroxy-4,4'-dimethoxybenzophenone, 4-hydroxybenzophenone, 3-(4-methylbenzylidene) camphor, ethyl 2-cyano-3,3-diphenylacrylate (etocrylene) and 2-ethylhexyl-2-cyano-3,3-diphenylacrylate (octocrylene)) were positive compared with the vehicle control. Benzhydrol, ethyl cinnamate and 2,2'-dihydroxy-4-methoxybenzophenone were weakly active. When each xenoestrogen was added to the cells along with ICI 182780, an estrogen receptor (ER) antagonist, the cell growth was reduced according to its doses. Therefore, the cell proliferation was suggested to generate through ER. Most of these chemicals were also positive using CHOOSER assay, a new method of testing estrogenic activity of xenoestrogen. Each xenoestrogen was also confirmed to bind to ERalpha and ERbeta using a human ER competitive binding assay against 17beta-estradiol. The concentration order of the strength of its inhibitory effect using both ERalpha and ERbeta was similar to that of MCF-7 cell proliferation assay, except for benzyl 4-hydroxybenzoate (B4HB). B4HB showed a stronger activity on CHOOSER assay and the competitive binding assay using both ERalpha and ERbeta, although there was no activity observed on MCF-7 cell proliferation assay. Our findings were to detect the estrogenic activity of etocrylene and octocrylene in vitro, in addition to confirming the activities of some ultraviolet absorbers as previously reported.

  2. Microwave-driven ultraviolet light sources

    DOEpatents

    Manos, Dennis M.; Diggs, Jessie; Ametepe, Joseph D.

    2002-01-29

    A microwave-driven ultraviolet (UV) light source is provided. The light source comprises an over-moded microwave cavity having at least one discharge bulb disposed within the microwave cavity. At least one magnetron probe is coupled directly to the microwave cavity.

  3. Ultraviolet Light: Some Considerations for Vision Stimulation.

    ERIC Educational Resources Information Center

    Knowlton, Marie

    1986-01-01

    The article examines evidence of visual impairment caused by excessive amounts of ultraviolet (UV) light. Among considerations when using a source of UV light for vision stimulation are the position of the child and teacher, use of window glass filters or protective glasses, and careful recordkeeping of all UV stimulation. (Author/JW)[

  4. Bright tunable ultraviolet squeezed light.

    PubMed

    Bell, A S; Riis, E; Ferguson, A I

    1997-04-15

    We have produced bright tunable squeezed light by second-harmonic generation in a singly resonant cavity. We have investigated the effect of input coupling and fundamental power on the squeezing. Up to 400 mW of continuous-wave mode-locked tunable squeezed light was produced at wavelengths as short as 389 nm, and more than 1.5 dB of squeezing was inferred.

  5. Orientation of migratory birds under ultraviolet light.

    PubMed

    Wiltschko, Roswitha; Munro, Ursula; Ford, Hugh; Stapput, Katrin; Thalau, Peter; Wiltschko, Wolfgang

    2014-05-01

    In view of the finding that cryptochrome 1a, the putative receptor molecule for the avian magnetic compass, is restricted to the ultraviolet single cones in European Robins, we studied the orientation behaviour of robins and Australian Silvereyes under monochromatic ultraviolet (UV) light. At low intensity UV light of 0.3 mW/m(2), birds showed normal migratory orientation by their inclination compass, with the directional information originating in radical pair processes in the eye. At 2.8 mW/m(2), robins showed an axial preference in the east-west axis, whereas silvereyes preferred an easterly direction. At 5.7 mW/m(2), robins changed direction to a north-south axis. When UV light was combined with yellow light, robins showed easterly 'fixed direction' responses, which changed to disorientation when their upper beak was locally anaesthetised with xylocaine, indicating that they were controlled by the magnetite-based receptors in the beak. Orientation under UV light thus appears to be similar to that observed under blue, turquoise and green light, albeit the UV responses occur at lower light levels, probably because of the greater light sensitivity of the UV cones. The orientation under UV light and green light suggests that at least at the level of the retina, magnetoreception and vision are largely independent of each other.

  6. Optical Properties and Aging of Light Absorbing Secondary Organic Aerosol

    SciTech Connect

    Liu, Jiumeng; Lin, Peng; Laskin, Alexander; Laskin, Julia; Kathmann, Shawn M.; Wise, Matthew E.; Caylor, Ryan; Imholt, Felisha; Selimovic, Vanessa; Shilling, John E.

    2016-10-14

    The light-absorbing organic aerosol (OA), commonly referred to as “brown carbon (BrC)”, has attracted considerable attention in recent years because of its potential to affect atmospheric radiation balance, especially in the ultraviolet region and thus impact photochemical processes. A growing amount of data has indicated that BrC is prevalent in the atmosphere, which has motivated numerous laboratory and field studies; however, our understanding of the relationship between the chemical composition and optical properties of BrC remains limited. We conducted chamber experiments to investigate the effect of various VOC precursors, NOx concentrations, photolysis time and relative humidity (RH) on the light absorption of selected secondary organic aerosols (SOA). Light absorption of chamber generated SOA samples, especially aromatic SOA, was found to increase with NOx concentration, at moderate RH, and for the shortest photolysis aging times. The highest mass absorption coefficients (MAC) value is observed from toluene SOA products formed under high NOx conditions at moderate RH, in which nitro-aromatics were previously identified as the major light absorbing compounds. BrC light absorption is observed to decrease with photolysis time, correlated with a decline of the organonitrate fraction of SOA. SOA formed from mixtures of aromatics and isoprene absorb less visible and UV light than SOA formed from aromatic precursors alone on a mass basis. However, the mixed-SOA absorption was underestimated when optical properties were predicted using a two-product SOA formation model, as done in many current climate models. Further investigation, including analysis on detailed mechanisms, are required to explain the discrepancy.

  7. Spectrophotometry of Thin Films of Light-Absorbing Particles.

    PubMed

    Binks, Bernard P; Fletcher, Paul D I; Johnson, Andrew J; Marinopoulos, Ioannis; Crowther, Jonathan M; Thompson, Michael A

    2017-04-06

    Thin films of dispersions of light-absorbing solid particles or emulsions containing a light-absorbing solute all have a nonuniform distribution of light-absorbing species throughout the sample volume. This results in nonuniform light absorption over the illuminated area, which causes the optical absorbance, as measured using a conventional specular UV-vis spectrophotometer, to deviate from the Beer-Lambert relationship. We have developed a theoretical model to account for the absorbance properties of such films, which are shown to depend on the size and volume fraction of the light-absorbing particles plus other sample variables. We have compared model predictions with measured spectra for samples consisting of emulsions containing a dissolved light-absorbing solute. Using no adjustable parameters, the model successfully predicts the behavior of nonuniform, light-absorbing emulsion films with varying values of droplet size, volume fraction, and other parameters.

  8. Contact lens disinfection by ultraviolet light

    SciTech Connect

    Dolman, P.J.; Dobrogowski, M.J. )

    1989-12-15

    A 253.7-nm ultraviolet light with an intensity of 1,100 microW/cm2 was tested for its germicidal activity against contact lenses and storage solutions contaminated with various corneal pathogens. The exposure time necessary to reduce a concentration of organisms from 10(6)/ml to less than 10/ml was 30 seconds for Staphylococcus aureus, 60 seconds for Pseudomonas aeruginosa, and 84 seconds for Candida albicans. The time necessary to sterilize a suspension of 10(4)/ml Acanthamoeba polyphaga was less than three minutes with this technique. Four brands of soft contact lenses were exposed to ultraviolet light for over eight hours without changing their appearance, comfort, or refraction.

  9. Ultraviolet light detection using an optical microcavity.

    PubMed

    Harker, Audrey; Mehrabani, Simin; Armani, Andrea M

    2013-09-01

    Ultraviolet (UV) light exposure is connected to both physical and psychological diseases. As such, there is significant interest in developing sensors that can detect UV light in the mW/cm2 intensity range with a high signal-to-noise ratio. In this Letter, we demonstrate a UV sensor based on a silica integrated optical microcavity that has a linear operating response in both the forward and backward directions from 14 to 53 mW/cm2. The sensor response agrees with the developed predictive theory based on a thermodynamic model. Additionally, the signal-to-noise ratio is above 100 at physiologically relevant intensity levels.

  10. Inorganic volumetric light source excited by ultraviolet light

    DOEpatents

    Reed, S.; Walko, R.J.; Ashley, C.S.; Brinker, C.J.

    1994-04-26

    The invention relates to a composition for the volumetric generation of radiation. The composition comprises a porous substrate loaded with a component capable of emitting radiation upon interaction with an exciting radiation. Preferably, the composition is an aerogel substrate loaded with a component, e.g., a phosphor, capable of interacting with exciting radiation of a first energy, e.g., ultraviolet light, to produce radiation of a second energy, e.g., visible light. 4 figures.

  11. Inorganic volumetric light source excited by ultraviolet light

    DOEpatents

    Reed, Scott; Walko, Robert J.; Ashley, Carol S.; Brinker, C. Jeffrey

    1994-01-01

    The invention relates to a composition for the volumetric generation of radiation. The composition comprises a porous substrate loaded with a component capable of emitting radiation upon interaction with an exciting radiation. Preferably, the composition is an aerogel substrate loaded with a component, e.g., a phosphor, capable of interacting with exciting radiation of a first energy, e.g., ultraviolet light, to produce radiation of a second energy, e.g., visible light.

  12. Light absorbing carbon emissions from commercial shipping

    NASA Astrophysics Data System (ADS)

    Lack, Daniel; Lerner, Brian; Granier, Claire; Baynard, Tahllee; Lovejoy, Edward; Massoli, Paola; Ravishankara, A. R.; Williams, Eric

    2008-07-01

    Extensive measurements of the emission of light absorbing carbon aerosol (LAC) from commercial shipping are presented. Vessel emissions were sampled using a photoacoustic spectrometer in the Gulf of Mexico region. The highest emitters (per unit fuel burnt) are tug boats, thus making significant contributions to local air quality in ports. Emission of LAC from cargo and non cargo vessels in this study appears to be independent of engine load. Shipping fuel consumption data (2001) was used to calculate a global LAC contribution of 133(+/-27) Ggyr-1, or ~1.7% of global LAC. This small fraction could have disproportionate effects on both air quality near port areas and climate in the Arctic if direct emissions of LAC occur in that region due to opening Arctic sea routes. The global contribution of this LAC burden was investigated using the MOZART model. Increases of 20-50 ng m-3 LAC (relative increases up to 40%) due to shipping occur in the tropical Atlantic, Indonesia, central America and the southern regions of South America and Africa.

  13. Light shield and cooling apparatus. [high intensity ultraviolet lamp

    NASA Technical Reports Server (NTRS)

    Meador, T. G., Jr. (Inventor)

    1974-01-01

    A light shield and cooling apparatus was developed for a high intensity ultraviolet lamp including water and high pressure air for cooling and additional apparatus for shielding the light and suppressing the high pressure air noise.

  14. STARCH-SOYBEAN OIL BASED ULTRAVIOLET ABSORBING COMPOSITES. PREPARATION, CHEMISTY AND POTENTIAL USES

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Excess steam jet-cooking aqueous slurries of starch and vegetable oils or other hydrophobic materials can produce stable aqueous starch-oil composites from renewable resources. Herein, ferulate-based ultraviolet absorbing lipids were synthesized by the lipase catalyzed transesterification of soybea...

  15. Vitamin A activates rhodopsin and sensitizes it to ultraviolet light.

    PubMed

    Miyazono, Sadaharu; Isayama, Tomoki; Delori, François C; Makino, Clint L

    2011-11-01

    The visual pigment, rhodopsin, consists of opsin protein with 11-cis retinal chromophore, covalently bound. Light activates rhodopsin by isomerizing the chromophore to the all-trans conformation. The activated rhodopsin sets in motion a biochemical cascade that evokes an electrical response by the photoreceptor. All-trans retinal is eventually released from the opsin and reduced to vitamin A. Rod and cone photoreceptors contain vast amounts of rhodopsin, so after exposure to bright light, the concentration of vitamin A can reach relatively high levels within their outer segments. Since a retinal analog, β-ionone, is capable of activating some types of visual pigments, we tested whether vitamin A might produce a similar effect. In single-cell recordings from isolated dark-adapted salamander green-sensitive rods, exogenously applied vitamin A decreased circulating current and flash sensitivity and accelerated flash response kinetics. These changes resembled those produced by exposure of rods to steady light. Microspectrophotometric measurements showed that vitamin A accumulated in the outer segments and binding of vitamin A to rhodopsin was confirmed in in vitro assays. In addition, vitamin A improved the sensitivity of photoreceptors to ultraviolet (UV) light. Apparently, the energy of a UV photon absorbed by vitamin A transferred by a radiationless process to the 11-cis retinal chromophore of rhodopsin, which subsequently isomerized. Therefore, our results suggest that vitamin A binds to rhodopsin at an allosteric binding site distinct from the chromophore binding pocket for 11-cis retinal to activate the rhodopsin, and that it serves as a sensitizing chromophore for UV light.

  16. Light Absorbing Particle (LAP) Measurements in the Lower Stratosphere

    NASA Technical Reports Server (NTRS)

    Baumgardner, D.; Raga, G. B.; Anderson, B.; Diskin, G.; Sachse, G.; Kok, G.

    2003-01-01

    This viewgraph presentation covers the capabilities and design of the Single Particle Soot Photometer (SP-2), and reviews its role on the Sage III Ozone Loss Validation Experiment (SOLVE II) field campaign during 2003. On SOLVE II the SP-2 was carried into the Arctic onboard a DC-8 aircraft, in order to determine the size distribution of light-absorbing and non light-absorbing particles in the stratosphere. Graphs and tables relate some of the results from SOLVE II.

  17. Contribution to the ultraviolet metagalactic background from radiative recombination in intervening absorbers

    NASA Astrophysics Data System (ADS)

    Liu, J. M.

    1997-05-01

    Recently, Haardt & Madau (HM) showed that QSO absorption-line systems are not only sinks of the ultraviolet metagalactic background (UMB), but also significant sources of the UMB due to recombination radiation within photoionized absorbers. We demonstrate that the contribution to the UMB from H I and He II recombination radiation may be less than Haardt & Madau's by a factor of about 0.4 if intervening absorbers are modeled as a slab illuminated isotropically on two sides and the recombination radiation is assumed to be isotropic. This is the case which most closely approximates QSOs absorption-line systems.

  18. Light Absorbing Aerosols in Mexico City

    NASA Astrophysics Data System (ADS)

    Marley, N. A.; Kelley, K. L.; Kilaparty, P. S.; Gaffney, J. S.

    2008-12-01

    The direct effects of aerosol radiative forcing has been identified by the IPCC as a major uncertainty in climate modeling. The DOE Megacity Aerosol Experiment-Mexico City (MAX-Mex), as part of the MILAGRO study in March of 2006, was undertaken to reduce these uncertainties by characterization of the optical, chemical, and physical properties of atmospheric aerosols emitted from this megacity environment. Aerosol samples collected during this study using quartz filters were characterized in the uv-visible-infrared by using surface spectroscopic techniques. These included the use of an integrating sphere approach combined with the use of Kubelka-Munk theory to obtain aerosol absorption spectra. In past work black carbon has been assumed to be the only major absorbing species in atmospheric aerosols with an broad band spectral profile that follows a simple inverse wavelength dependence. Recent work has also identified a number of other absorbing species that can also add to the overall aerosol absorption. These include primary organics from biomass and trash burning and secondary organic aerosols including nitrated PAHs and humic-like substances, or HULIS. By using surface diffuse reflection spectroscopy we have also obtained spectra in the infrared that indicate significant IR absorption in the atmospheric window-region. These data will be presented and compared to spectra of model compounds that allow for evaluation of the potential importance of these species in adding strength to the direct radiative forcing of atmospheric aerosols. This work was supported by the Office of Science (BER), U.S. Department of Energy, Grant No. DE-FG02-07ER64327 as part of the Atmospheric Science Program.

  19. The absorption of ultraviolet light by cell nuclei. A technique for identifying neoplastic change

    SciTech Connect

    Baisden, C.R.; Booker, D.; Wright, R.D. )

    1989-11-01

    A technique for measuring the absorption of 260-nm ultraviolet light by cell nuclei is described. The results of such measurements of normal thyroid epithelial cells and benign and malignant thyroid neoplastic cells demonstrate a progressive increase in absorbance that correlates with the histologic appearance of neoplasia. The possible theoretic basis for this phenomenon is explored. The increased nuclear absorbance observed in neoplastic cells is hypothesized to result from the disruption of hydrogen bonds between the DNA base pairs, which allows unwinding of the double helix and loss of the normal control of mitosis.

  20. Mesoporous silicate MCM-41 containing organic ultraviolet ray absorbents: Preparation, photostability and in vitro release

    NASA Astrophysics Data System (ADS)

    Ambrogi, V.; Perioli, L.; Marmottini, F.; Latterini, L.; Rossi, C.; Costantino, U.

    2007-05-01

    The mesoporous silicate MCM-41 was studied for its properties to adsorb and to influence the photostability and the release of three organic ultraviolet (UV) ray absorbents, namely benzophenone-3 (B3), benzophenone-2 (B2) and p-aminobenzoic acid (PABA). MCM-41 microcrystals have been loaded with the UV absorbents obtaining a good loading w/w percentage. The loaded samples have been characterized by chemical and thermal analyses, X-ray diffraction, N2 adsorption isotherms. Photochemical studies demonstrated that the UV-shielding properties of B2 were maintained whereas in other cases a small reduction of sunscreen protection range was noticed. B3 and B2 release from loaded MCM-41 formulations were studied and compared to those obtained from formulations containing free UV ray absorbent; no remarkable differences were observed in the release profiles.

  1. Light-absorbing Components in Lake Superior

    DTIC Science & Technology

    2010-01-01

    characterization of phytoplankton and detrital absorption properties in the Sargasso Sea . Umnol. Oceanogr. 34, 1706-1726. Kirk, j.T.O., 1994. Light and...Stephan, B., 1996. Absorption spectra of inorganic particles in the Irish Sea and their relevance to remote sensing of chlorophyll. Int. j. Remote Sens...the Pocono Plateau. Umnol. Oceanogr. 42, 239- 249. Owen, R.W., 1974. Optically effective area of particle ensembles in the sea . Umnol. Oceanogr. 19

  2. Measurements of Light Absorbing Particles on Tropical South American Glaciers

    NASA Astrophysics Data System (ADS)

    Schmitt, C. G.; All, J.; Schwarz, J. P.; Arnott, W. P.; Warthon, J.; Andrade, M.; Celestian, A. J.; Hoffmann, D.; Cole, R. J.; Lapham, E.; Horodyskyj, U. N.; Froyd, K. D.; Liao, J.

    2014-12-01

    Glaciers in the tropical Andes have been losing mass rapidly in recent decades. In addition to the documented increase in temperature, increases in light absorbing particulates deposited on glaciers could be contributing to the observed glacier loss. Here we present results of measurements of light absorbing particles from glaciers in Peru and Bolivia. Samples have been collected by American Climber Science Program volunteers and scientists at altitudes up to 6770 meters. Collected snow samples were melted and filtered in the field. A new inexpensive technique, the Light Absorption Heating Method (LAHM) has been developed for analysis of light absorbing particles collected on filters. Results from LAHM analysis are calibrated using filters with known amounts of fullerene soot, a common industrial surrogate for black carbon (BC). For snow samples collected at the same field location LAHM analysis and measurements from the Single Particle Soot Photometer (SP2) instrument are well correlated (r2 = 0.92). Co-located SP2 and LAHM filter analysis suggest that BC could be the dominant absorbing component of the light absorbing particles in some areas.

  3. High extraction efficiency ultraviolet light-emitting diode

    DOEpatents

    Wierer, Jonathan; Montano, Ines; Allerman, Andrew A.

    2015-11-24

    Ultraviolet light-emitting diodes with tailored AlGaN quantum wells can achieve high extraction efficiency. For efficient bottom light extraction, parallel polarized light is preferred, because it propagates predominately perpendicular to the QW plane and into the typical and more efficient light escape cones. This is favored over perpendicular polarized light that propagates along the QW plane which requires multiple, lossy bounces before extraction. The thickness and carrier density of AlGaN QW layers have a strong influence on the valence subband structure, and the resulting optical polarization and light extraction of ultraviolet light-emitting diodes. At Al>0.3, thinner QW layers (<2.5 nm are preferred) result in light preferentially polarized parallel to the QW plane. Also, active regions consisting of six or more QWs, to reduce carrier density, and with thin barriers, to efficiently inject carriers in all the QWs, are preferred.

  4. 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.

  5. 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...

  6. Optical properties and aging of light-absorbing secondary organic aerosol

    DOE PAGES

    Liu, Jiumeng; Lin, Peng; Laskin, Alexander; ...

    2016-10-14

    The light-absorbing organic aerosol (OA) commonly referred to as “brown carbon” (BrC) has attracted considerable attention in recent years because of its potential to affect atmospheric radiation balance, especially in the ultraviolet region and thus impact photochemical processes. A growing amount of data has indicated that BrC is prevalent in the atmosphere, which has motivated numerous laboratory and field studies; however, our understanding of the relationship between the chemical composition and optical properties of BrC remains limited. We conducted chamber experiments to investigate the effect of various volatile organic carbon (VOC) precursors, NOx concentrations, photolysis time, and relative humidity (RH) on the light absorptionmore » of selected secondary organic aerosols (SOA). Light absorption of chamber-generated SOA samples, especially aromatic SOA, was found to increase with NOx concentration, at moderate RH, and for the shortest photolysis aging times. The highest mass absorption coefficient (MAC) value is observed from toluene SOA products formed under high-NOx conditions at moderate RH, in which nitro-aromatics were previously identified as the major light-absorbing compounds. BrC light absorption is observed to decrease with photolysis time, correlated with a decline of the organic nitrate fraction of SOA. SOA formed from mixtures of aromatics and isoprene absorb less visible (Vis) and ultraviolet (UV) light than SOA formed from aromatic precursors alone on a mass basis. However, the mixed SOA absorption was underestimated when optical properties were predicted using a two-product SOA formation model, as done in many current climate models. Further investigation, including analysis on detailed mechanisms, are required to explain the discrepancy.« less

  7. Optical properties and aging of light-absorbing secondary organic aerosol

    NASA Astrophysics Data System (ADS)

    Liu, Jiumeng; Lin, Peng; Laskin, Alexander; Laskin, Julia; Kathmann, Shawn M.; Wise, Matthew; Caylor, Ryan; Imholt, Felisha; Selimovic, Vanessa; Shilling, John E.

    2016-10-01

    The light-absorbing organic aerosol (OA) commonly referred to as "brown carbon" (BrC) has attracted considerable attention in recent years because of its potential to affect atmospheric radiation balance, especially in the ultraviolet region and thus impact photochemical processes. A growing amount of data has indicated that BrC is prevalent in the atmosphere, which has motivated numerous laboratory and field studies; however, our understanding of the relationship between the chemical composition and optical properties of BrC remains limited. We conducted chamber experiments to investigate the effect of various volatile organic carbon (VOC) precursors, NOx concentrations, photolysis time, and relative humidity (RH) on the light absorption of selected secondary organic aerosols (SOA). Light absorption of chamber-generated SOA samples, especially aromatic SOA, was found to increase with NOx concentration, at moderate RH, and for the shortest photolysis aging times. The highest mass absorption coefficient (MAC) value is observed from toluene SOA products formed under high-NOx conditions at moderate RH, in which nitro-aromatics were previously identified as the major light-absorbing compounds. BrC light absorption is observed to decrease with photolysis time, correlated with a decline of the organic nitrate fraction of SOA. SOA formed from mixtures of aromatics and isoprene absorb less visible (Vis) and ultraviolet (UV) light than SOA formed from aromatic precursors alone on a mass basis. However, the mixed SOA absorption was underestimated when optical properties were predicted using a two-product SOA formation model, as done in many current climate models. Further investigation, including analysis on detailed mechanisms, are required to explain the discrepancy.

  8. Ultraviolet absorbance by diatom populations from the Weddell-Scotia Confluence

    SciTech Connect

    Neale, P.J.; Spector, A.M.

    1994-12-31

    Austral spring ozone depletion results in exposure of phytoplankton in the Weddell-Scotia Confluence to enhanced surface ultraviolet-B radiation (UV-B, 280 to 320 nanometers). Since this is an area of high phytoplankton biomass during the early spring, an investigation was made of possible effects of increased UV-B on the phytoplankton productivity during October and November 1993 aboard the R/V Nathaniel B. Palmer (UV-B/Ozone 93). The measurements made during the studies included phytoplankton UV absorbance (this paper) as well as phytoplankton photosynthesis, nutrient uptake, pigment composition, and growth rates. 10 refs., 3 figs.

  9. Field trials measuring the effects of ultraviolet-absorbing greenhouse plastic films on insect populations.

    PubMed

    Costa, H S; Robb, K L; Wilen, C A

    2002-02-01

    Field studies were conducted to compare insect population levels in greenhouse crops covered with plastics that block the transmission of UV light in two wavelength ranges. Crops grown in greenhouses under a plastic that blocked UV light at wavelengths of 380 nm and below had lower numbers of aphids and thrips compared with a plastic that blocked UV light at wavelengths of 360 nm and below. This is consistent with the results found for thrips in previous studies using small, completely enclosed tunnels with no plant material. The effects were not as dramatic in the commercial greenhouses, perhaps due to unfiltered light entering through the open sides of those greenhouses. There was no reduction in greenhouse whitefly, Trialeurodes vaporariorum Westwood, populations under the <380 UV-absorbing plastic compared to <360 nm UV-absorbing plastic in these field trials. This is inconsistent with results found in small, completely enclosed tunnels, where sticky traps caught a significantly higher proportion (95 +/- 2%) of released greenhouse whiteflies inside tunnels covered with <360 nm absorbing plastic compared with the <380 nm absorbing plastic. The results of these studies suggest that the type of greenhouse plastic used in a structure can affect population levels of some insect species, and may be useful tools in developing integrated pest management programs for insect management. The design of the greenhouse and amount of unfiltered light that enters the system appear to be important factors in determining the level of effect.

  10. The fungicidal effect of ultraviolet light on impression materials

    SciTech Connect

    Ishida, H.; Nahara, Y.; Tamamoto, M.; Hamada, T. )

    1991-04-01

    The effects of ultraviolet (UV) light on fungi and impression materials were tested. UV light (250 microW/cm2) killed most Candida organisms (10(3) cells/ml) within 5 minutes. UV light (8000 microW/cm2) killed most C. albicans (10(7) cells/ml) within 2 minutes of exposure. The effect of UV light on dimensional change and surface roughness of impression materials (irreversible hydrocolloid, agar, and silicone rubber) was tested. The results showed that neither dimensional change nor surface roughness of the impression materials were affected. The results of this study indicate that UV light disinfects impression materials that are contaminated with Candida organisms.

  11. Simultaneous determination of some ultraviolet-absorbing chemicals in sunscreen cosmetics using a high-performance liquid chromatography method.

    PubMed

    Liu, T; Wu, D

    2011-10-01

    A method of gradient elution high-performance liquid chromatography (HPLC) for simultaneous determination of 11 different ultraviolet-absorbing chemicals of phenylbenzlmldazole sulphonic acid, 4-aminobenzoic acid, benzophenone-4, benzophenone-3, isoamyl p-methoxycinnamate, 4-methylbenzylidene camphor, octocrylene, ethylhexyl methoxycinnamate, homosalate, ethylhexyl salicylate, methylene bis-benzotriazolyl tetramethylbutyl phenol was developed for the application to sunscreen cosmetic products. In this study, an Agilent SB-C18 analytical column (250 × 4.6 mm, 5 μm) was utilized and methanol, tetrahydrofuran and perchloric acid aqueous solution (0.2 mL HClO(4) + 300 mL H(2)O) were used for gradient elution at a total flow rate of 1.0 mL min(-1). The optimum conditions for 11 different ultraviolet-absorbing chemicals analyses were investigated. All calibration curves showed good linear regression with UV detection (311 nm) within test ranges. The correlation coefficients were better than 0.999 in all cases. The assay was simple, selective, convenient and reproducible and is suitable for the determination of ultraviolet-absorbing chemicals in commercial sunscreen cosmetic products. The use frequency of 11 different ultraviolet absorbents in 100 sunscreen cosmetics was investigated and statistically analysed. The ultraviolet absorbent of maximum use frequency was ethylhexyl methoxycinnamate.

  12. A Response to "Ultraviolet Light: Some Considerations for Vision Stimulation."

    ERIC Educational Resources Information Center

    Wright, Suzette

    1987-01-01

    As there is uncertainty surrounding black light safety, caution should be exercised in using it as a vision training tool with visually handicapped students--particularly aphakic and albino students, young students, and those taking photosensitizing drugs. The use of ultraviolet-blocking filters or lenses is recommended during black light…

  13. Inactivation of Campylobacter jejuni on poultry by ultraviolet light

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Campylobacter jejuni is a foodborne pathogen which is commonly associated with poultry, and is responsible for many foodborne illness outbreaks. Ultraviolet light (UV-C) is a U.S. Food and Drug Administration approved technology that can be used to treat foods and food contact surfaces. In this stud...

  14. Preventing Ultraviolet Light-Induced Damage: The Benefits of Antioxidants

    ERIC Educational Resources Information Center

    Yip, Cheng-Wai

    2007-01-01

    Extracts of fruit peels contain antioxidants that protect the bacterium "Escherichia coli" against damage induced by ultraviolet light. Antioxidants neutralise free radicals, thus preventing oxidative damage to cells and deoxyribonucleic acid. A high survival rate of UV-exposed cells was observed when grapefruit or grape peel extract was…

  15. Benefits and Costs of Ultraviolet Fluorescent Lighting

    PubMed Central

    Lestina, Diane C.; Miller, Ted R.; Knoblauch, Richard; Nitzburg, Marcia

    1999-01-01

    Objective To demonstrate the improvements in detection and recognition distances using fluorescent roadway delineation and auxiliary ultra-violet (UVA) headlights and determine the reduction in crashes needed to recover increased costs of the UVA/flourescent technology. Methods Field study comparisons with and without UVA headlights. Crash types potentially reduced by UVA/flourescent technology were estimated using annual crash and injury incidence data from the General Estimates System (1995–1996) and the 1996 Fatality Analysis Reporting System. Crash costs were computed based on body region and threat-to-life injury severity. Results Significant improvements in detection and recognition distances for pedestrian scenarios, ranging from 34% to 117%. A 19% reduction in nighttime motor vehicle crashes involving pedestrians or pedal-cycles will pay for the additional UVA headlight costs. Alternatively, a 5.5% reduction in all relevant nighttime crashes will pay for the additional costs of UVA headlights and fluorescent highway paint combined. Conclusions If the increased detection and recognition distances resulting from using UVA/flourescent technology as shown in this field study reduce relevant crashes by even small percentages, the benefit cost ratios will still be greater than 2; thus, the UVA/flourescent technology is very cost-effective and a definite priority for crash reductions.

  16. Tailored Buckling Microlattices as Reusable Light-Weight Shock Absorbers.

    PubMed

    Frenzel, Tobias; Findeisen, Claudio; Kadic, Muamer; Gumbsch, Peter; Wegener, Martin

    2016-07-01

    Structures and materials absorbing mechanical (shock) energy commonly exploit either viscoelasticity or destructive modifications. Based on a class of uniaxial light-weight geometrically nonlinear mechanical microlattices and using buckling of inner elements, either a sequence of snap-ins followed by irreversible hysteretic - yet repeatable - self-recovery or multistability is achieved, enabling programmable behavior. Proof-of-principle experiments on three-dimensional polymer microstructures are presented.

  17. Cosmic ultraviolet background radiation and zodiacal light

    NASA Technical Reports Server (NTRS)

    Tennyson, P. D.; Henry, R. C.; Feldman, P. D.; Hartig, G. F.

    1988-01-01

    Spectroscopic measurements of the diffuse cosmic UV background in the 1700-2850-A range are presented. In agreement with previous results, the data have resulted in the detection at high Galactic latitude of an intensity of 300 + or - 100 photons/sq cm s sr A at 1800 A without correction for starlight or airglow, a similar intensity over the 1900-2500-A range after correction for measured airglow, and a similar intensity over the 2500-2800-A range after correction for zodiacal light. It is suggested that this radiation may originate partly in line radiation from a Galactic halo and partly from extragalactic sources, perhaps the integrated light of distant galaxies.

  18. Ultraviolet light curves of V535 Arae

    NASA Technical Reports Server (NTRS)

    Eaton, Joel A.

    1991-01-01

    The light curve of V535 Ara is determined from observations of this long-period W UMa binary in the UV, and its gravity darkening is estimated. The UV colors and spectral type correspond to (B - V)0 = 0.24, or A8V, and imply that the star should have very little residual convection in its envelope. It is concluded that the gravity darkening is large, as in a radiative star, unless it is modified by circulation in the common envelope, or unless all stars this warm are convective. Four solutions are obtained to a combination of optical and UV light curves, two for high radiative gravity darkening, and two for low convective gravity darkening. The light curves were fitted equally well in all four cases, while in all but the one with low-gravity darkening and a hot inner face there was a rather large global temperature difference between the two stars. It is suggested that the W UMa binaries are found only at spectral types later than about A8 because their outer envelopes must be convective to transfer luminosity.

  19. Implications of an updated ultraviolet background for the ionization mechanisms of intervening Ne VIII absorbers

    NASA Astrophysics Data System (ADS)

    Hussain, Tanvir; Khaire, Vikram; Srianand, Raghunathan; Muzahid, Sowgat; Pathak, Amit

    2017-04-01

    Ne VIII absorbers seen in QSO spectra are useful tracers of warm ionized gas, when collisional ionization is the dominant ionization process. While photoionization by the ultraviolet background (UVB) is a viable option, it tends to predict large line-of-sight thickness for the absorbing gas. Here, we study the implications of the recently updated UVB at low z to understand the ionization mechanisms of intervening Ne VIII absorbers. With the updated UVB, one typically needs higher density and metallicity to reproduce the observed ionic column densities under photoionization. Both reduce the inferred line-of-sight thicknesses of the absorbers. We find a critical density of ≥5 × 10-5 cm-3 above which the observed N({Ne VIII})/N({O VI}) can be reproduced by pure collisional processes. If the gas is of near solar metallicity (as measured for the low ions) then the cooling time-scales will be small (<108 yrs). Therefore, a continuous injection of heat is required in order to enhance the detectability of the collisionally ionized gas. Using photoionization models we find that in almost all Ne VIII systems the inferred low ion metallicity is near solar or supersolar. If we assume the Ne VIII phase to have similar metallicities then photoionization can reproduce the observed N({Ne VIII})/N({O VI}) without the line-of-sight thickness being unreasonably large and avoids cooling issues related to the collisional ionization at these metallicities. However, the indication of broad Lyα absorption in a couple of systems, if true, suggests that the Ne VIII phase is distinct from the low ion phase having much lower metallicity.

  20. Photoreactivation and other ultraviolet/visible light effects on DNA in human skin

    SciTech Connect

    Sutherland, B.M.; Blackett, A.D.; Feng, N.I.; Freeman, S.E.; Ogut, E.S.; Gange, R.W.; Sutherland, J.C.

    1984-01-01

    A computer-based system was devised for examining low levels (1 dimer/10/sup 8/ d) of DNA damage in human skin exposed to ultraviolet or visible radiation. The production of measurable levels of dimers was determined for light of wavelengths absorbed directly by DNA (290-320 nm). Exposure of skin to uv-A (320-380 nm) sources also produced significant numbers of endonuclease-sensitive sites. The immediate pigment darkening reaction (IPD) was tested to see whether IPD protects against uv-induced dimer formation. 29 references, 2 figures, 1 table. (ACR)

  1. Light Absorbers and Catalysts for Solar to Fuel Conversion

    NASA Astrophysics Data System (ADS)

    Kornienko, Nikolay I.

    Increasing fossil fuel consumption and the resulting consequences to the environment has propelled research into means of utilizing alternative, clean energy sources. Solar power is among the most promising of renewable energy sources but must be converted into an energy dense medium such as chemical bonds to render it useful for transport and energy storage. Photoelectrochemistry (PEC), the splitting of water into oxygen and hydrogen fuel or reducing CO 2 to hydrocarbon fuels via sunlight is a promising approach towards this goal. Photoelectrochemical systems are comprised of several components, including light absorbers and catalysts. These parts must all synergistically function in a working device. Therefore, the continual development of each component is crucial for the overall goal. For PEC systems to be practical for large scale use, the must be efficient, stable, and composed of cost effective components. To this end, my work focused on the development of light absorbing and catalyst components of PEC solar to fuel converting systems. In the direction of light absorbers, I focused of utilizing Indium Phosphide (InP) nanowires (NWs) as photocathodes. I first developed synthetic techniques for InP NW solution phase and vapor phase growth. Next, I developed light absorbing photocathodes from my InP NWs towards PEC water splitting cells. I studied cobalt sulfide (CoSx) as an earth abundant catalyst for the reductive hydrogen evolution half reaction. Using in situ spectroscopic techniques, I elucidated the active structure of this catalyst and offered clues to its high activity. In addition to hydrogen evolution catalysts, I established a new generation of earth abundant catalysts for CO2 reduction to CO fuel/chemical feedstock. I first worked with molecularly tunable homogeneous catalysts that exhibited high selectivity for CO2 reduction in non-aqueous media. Next, in order to retain molecular tunability while achieving stability and efficiency in aqueous

  2. Ultraviolet nanoimprinted polymer nanostructure for organic light emitting diode application

    NASA Astrophysics Data System (ADS)

    Jeon, Sohee; Kang, Jae-Wook; Park, Hyung-Dol; Kim, Jang-Joo; Youn, Jae R.; Shim, Jongyoup; Jeong, Jun-ho; Choi, Dae-Geun; Kim, Ki-Don; Altun, Ali Ozhan; Kim, Se-Heon; Lee, Yong-Hee

    2008-06-01

    Light extraction efficiency of a conventional organic light emitting diode (OLED) remains limited to approximately 20% as most of the emission is trapped in the waveguide and glass modes. An etchless simple method was developed to fabricate two-dimensional nanostructures on glass substrate directly by using ultraviolet (UV) curable polymer resin and UV nanoimprint lithography in order to improve output coupling efficiency of OLEDs. The enhancement of the light extraction was predicted by the three-dimensional finite difference time domain method. OLEDs integrated on nanoimprinted substrates enhanced electroluminance intensity by up to 50% compared to the conventional device.

  3. Dualex: A New Instrument for Field Measurements of Epidermal Ultraviolet Absorbance by Chlorophyll Fluorescence

    NASA Astrophysics Data System (ADS)

    Goulas, Yves; Cerovic, Zoran G.; Cartelat, Aurélie; Moya, Ismaël

    2004-08-01

    Dualex (dual excitation) is a field-portable instrument, hereby described, for the assessment of polyphenolic compounds in leaves from the measurement of UV absorbance of the leaf epidermis by double excitation of chlorophyll fluorescence. The instrument takes advantage of a feedback loop that equalizes the fluorescence level induced by a reference red light to the UV-light-induced fluorescence level. This allows quick measurement from attached leaves even under field conditions. The use of light-emitting diodes and of a leaf-clip configuration makes Dualex a user-friendly instrument with potential applications in ecophysiological research, light climate analysis, agriculture, forestry, horticulture, pest management, selection of medicinal plants, and wherever accumulation of leaf polyphenolics is involved in plant responses to the environment.

  4. Semiconductor meta-surface based perfect light absorber.

    PubMed

    Liu, Guiqiang; Nie, Yiyou; Fu, Guolan; Liu, Xiaoshan; Liu, Yi; Tang, Li; Liu, Zhengqi

    2017-04-21

    We numerically proposed and demonstrated a semiconductor meta-surface light absorber, which consists of a silicon patches array on a silicon thin-film and an opaque silver substrate. The Mie resonances of the silicon patches and the fundamental cavity mode of the ultra-thin silicon film couple strongly to the incident optical field, leading to a multi-band perfect absorption. The maximal absorption is above 99.5% and the absorption is polarization-independent. Moreover, the absorption behavior is scalable in the frequency region via tuning the structural parameters. These features hold the absorber platform with wide applications in optoelectronics such as hot-electron excitation and photo-detection.

  5. Deep ultraviolet light-emitting and laser diodes

    NASA Astrophysics Data System (ADS)

    Khan, Asif; Asif, Fatima; Muhtadi, Sakib

    2016-02-01

    Nearly all the air-water purification/polymer curing systems and bio-medical instruments require 250-300 nm wavelength ultraviolet light for which mercury lamps are primarily used. As a potential replacement for these hazardous mercury lamps, several global research teams are developing AlGaN based Deep Ultraviolet (DUV) light emitting diodes (LEDs) and DUV LED Lamps and Laser Diodes over Sapphire and AlN substrates. In this paper, we review the current research focus and the latest device results. In addition to the current results we also discuss a new quasipseudomorphic device design approach. This approach which is much easier to integrate in a commercial production setting was successfully used to demonstrate UVC devices on Sapphire substrates with performance levels equal to or better than the conventional relaxed device designs.

  6. Fragmentation of mercury compounds under ultraviolet light irradiation

    NASA Astrophysics Data System (ADS)

    Kokkonen, E.; Löytynoja, T.; Hautala, L.; Jänkälä, K.; Huttula, M.

    2015-08-01

    Ultraviolet light induced photofragmentation of mercury compounds is studied experimentally with electron energy resolved photoelectron-photoion coincidence techniques and theoretically with computational quantum chemical methods. A high resolution photoelectron spectrum using synchrotron radiation is presented. Fragmentation of the molecule is studied subsequent to ionization to the atomic-mercury-like d orbitals. State dependent fragmentation behaviour is presented and specific reactions for dissociation pathways are given. The fragmentation is found to differ distinctly in similar orbitals of different mercury compounds.

  7. Fragmentation of mercury compounds under ultraviolet light irradiation

    SciTech Connect

    Kokkonen, E.; Hautala, L.; Jänkälä, K.; Huttula, M.; Löytynoja, T.

    2015-08-21

    Ultraviolet light induced photofragmentation of mercury compounds is studied experimentally with electron energy resolved photoelectron-photoion coincidence techniques and theoretically with computational quantum chemical methods. A high resolution photoelectron spectrum using synchrotron radiation is presented. Fragmentation of the molecule is studied subsequent to ionization to the atomic-mercury-like d orbitals. State dependent fragmentation behaviour is presented and specific reactions for dissociation pathways are given. The fragmentation is found to differ distinctly in similar orbitals of different mercury compounds.

  8. Large area, surface discharge pumped, vacuum ultraviolet light source

    DOEpatents

    Sze, Robert C.; Quigley, Gerard P.

    1996-01-01

    Large area, surface discharge pumped, vacuum ultraviolet (VUV) light source. A contamination-free VUV light source having a 225 cm.sup.2 emission area in the 240-340 nm region of the electromagnetic spectrum with an average output power in this band of about 2 J/cm.sup.2 at a wall-plug efficiency of approximately 5% is described. Only ceramics and metal parts are employed in this surface discharge source. Because of the contamination-free, high photon energy and flux, and short pulse characteristics of the source, it is suitable for semiconductor and flat panel display material processing.

  9. Large area, surface discharge pumped, vacuum ultraviolet light source

    DOEpatents

    Sze, R.C.; Quigley, G.P.

    1996-12-17

    Large area, surface discharge pumped, vacuum ultraviolet (VUV) light source is disclosed. A contamination-free VUV light source having a 225 cm{sup 2} emission area in the 240-340 nm region of the electromagnetic spectrum with an average output power in this band of about 2 J/cm{sup 2} at a wall-plug efficiency of approximately 5% is described. Only ceramics and metal parts are employed in this surface discharge source. Because of the contamination-free, high photon energy and flux, and short pulse characteristics of the source, it is suitable for semiconductor and flat panel display material processing. 3 figs.

  10. Black carbon and other light-absorbing aerosols in snow

    NASA Astrophysics Data System (ADS)

    Wang, X.; Doherty, S. J.; Warren, S. G.; Fu, Q.

    2011-12-01

    Black carbon (BC), organic carbon (OC), and mineral dust are the most important light-absorbing aerosols (LAA) in snow. The physical, chemical and optical properties of these aerosols differ greatly; the different spectral dependences of their light-absorption can be used to quantify their concentrations in snow. A field campaign was conducted in January and February of 2010 to measure the LAA in snow across northern China. About 400 snow samples were collected at 46 sites in 6 provinces (Huang et al. 2011). Light absorption by mineral dust is due to iron oxides, so iron was determined by chemical analysis of filters and meltwater. To obtain concentrations of the absorbers, BC, OC, and Fe were assumed to have mass absorption cross-sections at 550 nm of 6.3, 0.3, and 0.9 m2/g respectively, and absorption Ångstrom exponents of 1.1, 6, and 3. The lowest values of all LAA are in the remote northeast, at latitude 51°N on the border of Siberia.Median values in surface snow there are 75 ppb BC, 150 ppb OC, and 45 ppb Fe. Farther south, in the industrial northeast, median values are 1000 ppb BC, 4200 ppb OC, and 500 ppb Fe. The grassland of Inner Mongolia is dominated by OC in soil dust of local origin: 560 ppb BC, 8000 ppb OC, 430 ppb Fe. In the Qilian Mountains at the northern boundary of the Tibetan Plateau the surface snow has 70 ppb BC, 2800 ppb OC, and 550 ppb Fe. The fraction of light absorption due to Fe is ~30% in the Qilian Mountains. Elsewhere BC and OC dominate the absorption, so Fe contributes <10% even though the Fe concentrations are as high as the Qilian values.

  11. Study of alternative capping and absorber layers for extreme ultraviolet (EUV) masks for sub-16nm half-pitch nodes

    NASA Astrophysics Data System (ADS)

    Rastegar, Abbas; House, Matthew; Tian, Ruahi; Laursen, Thomas; Antohe, Alin; Kearney, Patrick

    2014-04-01

    Multiple challenges, including the availability of a reliable high power source, defect free mask, and proper resist material, have forced extreme ultraviolet (EUV) lithography to be considered for sub-10 nm half-pitch nodes. Therefore, techniques such as phase shift masks (PSMs) or high numerical aperture (NA) lithography might be considered. Such techniques require thin EUV absorber materials to be optimized to reduce EUV mask shadowing effects. Despite the challenges in dry etching of Ni and finding proper chemistries with a high etch selectivity to suitable capping materials, we decided to examine the chemical stability of Ni for existing mask cleaning chemistries. Ni, after Ag, has the highest absorption in EUV light at λ = 13.5 nm, which makes it a proper candidate—in pure form or in mixing with other elements—for thin absorber film. Depending on the composition of the final material, proper integration schemes will be developed. We studied Ni stability in commonly used mask cleaning processes based on ammonium hydroxide/ hydrogen peroxide (APM) and water mixtures. Ni films deposited with an ion beam deposition technique with a thickness of 35 nm are sufficient to totally absorb EUV light at λ = 13.5 nm. Multiple cleanings of these Ni films resulted in Ni oxidation— confirmed by time-of-flight secondary ion mass spectroscopy (TOF-SIMS) analysis as NiO with thickness about 1.5 nm. Furthermore, Ni oxidation processes are self-limiting and oxide layer thickness did not increase with a further cleaning. A three minute exposure to sulfuric acid/hydrogen peroxide mixture (SPM) can remove NiO and Ni totally. To protect Ni film from etching by SPM chemistry a 3 nm Si capping was used on top of Ni film. However, Si capping was removed by APM chemistry and could not protect Ni film against SPM chemistry. TiO2 may be a very good capping layer for EUV optics but it is not suitable for EUV mask blanks and will be removed by APM chemistries.

  12. Effects of ultraviolet light on the eye: Role of protective glasses

    SciTech Connect

    Kuijk, F.J.G.M. van )

    1991-12-01

    Global atmospheric changes such as depletion of ozone in the stratosphere are though to lead to increased levels of ultraviolet radiation on earth. This can have adverse effects on human health, and long-term effects of ultraviolet light on the eye are of increasing concern. Ultraviolet light exposure to the eye has been associated with cataract formation and retinal degeneration. In both cases, it is hypothesized that ultraviolet light can initiate formation of free radicals, which can cause protein modification and lipid peroxidation. Several procedures can be recommended to prevent ultraviolet light damage to the eye, such as the use of suitable protective glasses when outdoors. 101 refs., 2 figs. 1 tab.

  13. Suppressive action of near-ultraviolet light on ouabain resistance induced by far-ultraviolet light in Chinese hamster cells.

    PubMed

    Suzuki, F; Han, A; Hill, C K; Elkind, M M

    1983-03-01

    The interaction between ultraviolet light (UV-C) from germicidal lamps (254 nm) and near-ultraviolet light (UV-B) from Westinghouse Sun Lamps (290-345 nm) was studied in Chinese hamster V79 cells by measuring the effectiveness of combined exposures to induce the resistance to 6-thioguanine or to ouabain. Exposure of cells to a conditioning dose of UV-B (approximately 70% survival) results in significant inhibition of the induction by UV-C of cells resistant to ouabain. The inhibition is lost, however, if cells are incubated for 12 h at 37 degrees C between exposures. Inhibition is also observed when cells are preirradiated with a dose of UV-B filtered with polystyrene (300-345 nm) which, in itself, has no effect on cell killing. Conditioning exposures of unfiltered or filtered UV-B light do not inhibit the induction of 6-thioguanine-resistant cells by UV-C light, and the effects of UV-B and UV-C light are largely independent.

  14. [Simultaneous determination of migration amounts of antioxidants and ultraviolet absorbents by high performance liquid chromatography in food contact materials].

    PubMed

    Li, Chengfa; Li, Ying; Chen, Zhinan; Liang, Feng; Chen, Xuhui; Wu, Shaojing; Li, Yongtao; Sun, Xiaoying

    2014-06-01

    An efficient analytical method for the quantitative determination of migration levels of antioxidants and ultraviolet absorbents in food contact materials by high performance liquid chromatography (HPLC) has been developed. The analytical method showed good linearity with the correlation coefficients (r2) > or = 0.999 8 for all the compounds. The limits of detection were between 0.01 mg/L and 0.22 mg/L and the limits of quantification were in the range of 0.03 to 0.85 mg/L for the 23 analytes. According to the European Union Directive No 10/2011, five food simulants were investigated: 30 g/L acetic acid, 10% (v/v) ethanol, 20% (v/v) ethanol, 50% (v/v) ethanol, and fatty food simulant (isooctane). The recoveries were in the range of 92.8%-117.7%, with the relative standard deviations of 0.95%-9.72%. The effects of different experimental conditions on the recoveries of antioxidants and UV absorbents were studied. The results showed that the method is accurate and stable, and can meet the requirements of European Commission Regulation (EU) No 10/2011 and GB 9685-2008 for the specific migration limits (SML) of the antioxidants and ultraviolet absorbents in real food contact plastic materials and article samples. The method has been applied to determine the migration levels of antioxidants and ultraviolet absorbents in different simulants from the migration tests of 30 batches of food contact material samples.

  15. Cylindrical plasmas generated by an annular beam of ultraviolet light

    SciTech Connect

    Thomas, D. M.; Allen, J. E.

    2015-07-15

    We investigate a cylindrical plasma system with ionization, by an annular beam of ultraviolet light, taking place only in the cylinder's outer region. In the steady state, both the outer and inner regions contain a plasma, with that in the inner region being uniform and field-free. At the interface between the two regions, there is an infinitesimal jump in ion density, the magnitude approaching zero in the quasi-neutral (λ{sub D} → 0) limit. The system offers the possibility of producing a uniform stationary plasma in the laboratory, hitherto obtained only with thermally produced alkali plasmas.

  16. Effects of ultraviolet light on Hymenolepis diminuta ova and cysticercoids

    SciTech Connect

    McGavock, W.D.; Howard, K.E.

    1980-07-01

    The ova and cysticercoids of Hymenolepis diminuta were exposed to a 2537 A wave length of ultraviolet light for various time periods. Development was extremely impaired in the cysts which had been irradiated for 30 and 60 minutes. When these were administered to the final host no tapeworms developed. From 113 intermediate host beetle larvae fed with irradiated ova, only three cysticercoids were recovered. Development was impaired in both cases and the infective rate of irradiated ova and cysts of the least exposed groups was lower than that of the controls.

  17. Organic molecules and nanoparticles in inorganic crystals: Vitamin C in CaCO3 as an ultraviolet absorber

    NASA Astrophysics Data System (ADS)

    Sato, H.; Ikeya, M.

    2004-03-01

    Organic molecules and nanoparticles embedded in inorganic crystalline lattices have been studied to add different properties and functions to composite materials. Calcium carbonate was precipitated by dropping an aqueous solution of CaCl2 into that of Na2CO3 containing dissolved vitamin C (ascorbic acid). The optical absorption ascribed to divalent ascorbate anions in the lattice was observed in the ultraviolet B (wavelength: 280-315 nm) region, while solid vitamin C exhibited absorption in the ultraviolet C (100-280 nm) region. The divalent ascorbate anion is only stable in CaCO3 due to the absence of oxygen molecules. Doping CaCO3 with nanoparticles of ZnO also enhanced the absorption in the ultraviolet A (315-380 nm) region. These composite materials are suggested for use as UV absorbers.

  18. Disinfection of swine wastewater using chlorine, ultraviolet light and ozone.

    PubMed

    Macauley, John J; Qiang, Zhimin; Adams, Craig D; Surampalli, Rao; Mormile, Melanie R

    2006-06-01

    Veterinary antibiotics are widely used at concentrated animal feeding operations (CAFOs) to prevent disease and promote growth of livestock. However, the majority of antibiotics are excreted from animals in urine, feces, and manure. Consequently, the lagoons used to store these wastes can act as reservoirs of antibiotics and antibiotic-resistant bacteria. There is currently no regulation or control of these systems to prevent the spread of these bacteria and their genes for antibiotic resistance into other environments. This study was conducted to determine the disinfection potential of chlorine, ultraviolet light and ozone against swine lagoon bacteria. Results indicate that a chlorine dose of 30 mg/L could achieve a 2.2-3.4 log bacteria reduction in lagoon samples. However, increasing the dose of chlorine did not significantly enhance the disinfection activity due to the presence of chlorine-resistant bacteria. The chlorine resistant bacteria were identified to be closely related to Bacillus subtilis and Bacillus licheniformis. A significant percentage of lagoon bacteria were not susceptible to the four selected antibiotics: chlortetracycline, lincomycin, sulfamethazine and tetracycline (TET). However, the presence of both chlorine and TET could inactivate all bacteria in one lagoon sample. The disinfection potential of UV irradiation and ozone was also examined. Ultraviolet light was an effective bacterial disinfectant, but was unlikely to be economically viable due to its high energy requirements. At an ozone dose of 100 mg/L, the bacteria inactivation efficiency could reach 3.3-3.9 log.

  19. Modeling the Effect of Polychromatic Light in Quantitative Absorbance Spectroscopy

    ERIC Educational Resources Information Center

    Smith, Rachel; Cantrell, Kevin

    2007-01-01

    Laboratory experiment is conducted to give the students practical experience with the principles of electronic absorbance spectroscopy. This straightforward approach creates a powerful tool for exploring many of the aspects of quantitative absorbance spectroscopy.

  20. Selective visualization of gene structure with ultraviolet light

    SciTech Connect

    Wang, Z.; Becker, M.M.

    1988-02-01

    The ability of the ultraviolet (UV) footprinting technique to detect chromatin has been investigated in vitro. Two basic types of chromatin, a phased nucleosome and a phased nucleosome containing a phased H1 protein, have been reconstituted onto a cloned 5S ribosomal RNA gene from sea urchin. The histone-DNA interactions in each complex have been probed with exonuclease III, DNase I, dimethyl sulfate, and UV light. Whereas DNase I and exonuclease III readily detect interactions between histones and DNA, UV light and dimethyl sulfate do not. In contrast to histone-DNA interactions, we demonstrate that intimate sequence-specific contacts between the same sea urchin 5S DNA and the Xenopus laevis transcription factor IIIA (TFIIIA) are readily detected with UV light. Since the sensitivity of UV light for TFIIIA contacts is similar to its sensitivity for other regulatory protein-DNA contacts, these studies demonstrate the feasibility of using UV light to selectively visualize regulatory protein-DNA interactions in vivo with little or no interference from histone-DNA interactions.

  1. ULTRAVIOLET LIGHT CURVES OF SUPERNOVAE WITH THE SWIFT ULTRAVIOLET/OPTICAL TELESCOPE

    SciTech Connect

    Brown, Peter J.; Roming, Peter W. A.; Nousek, John; Vanden Berk, Daniel; Holland, Stephen T.; Immler, Stefan; Gehrels, Neil; Panagia, Nino; Still, Martin

    2009-05-15

    We present ultraviolet (UV) observations of supernovae (SNe) obtained with the UltraViolet/Optical Telescope (UVOT) on board the Swift spacecraft. This is the largest sample of UV light curves from any single instrument and covers all major SN types and most subtypes. The UV light curves of SNe Ia are fairly homogenous, while SNe Ib/c and IIP show more variety in their light-curve shapes. The UV-optical colors clearly differentiate SNe Ia and IIP, particularly at early times. The color evolution of SNe IIP, however, makes their colors similar to SNe Ia at about 20 days after explosion. SNe Ib/c are shown to have varied UV-optical colors. The use of UV colors to help type SNe will be important for high-redshift SNe discovered in optical observations. These data can be added to ground-based optical and near infrared data to create bolometric light curves of individual objects and as checks on generic bolometric corrections used in the absence of UV data. This sample can also be compared with rest-frame UV observations of high-redshift SNe observed at optical wavelengths.

  2. Ultraviolet light exposure, skin cancer risk and vitamin D production

    PubMed Central

    RIVAS, MIGUEL; ROJAS, ELISA; ARAYA, MARÍA C.; CALAF, GLORIA M.

    2015-01-01

    The danger of overexposure to solar ultraviolet radiation has been widely reviewed since the 1980s due to the depletion of the ozone layer. However, the benefits of mild exposure of the skin to ultraviolet (UV) light have not been widely investigated. Numerous reports have demonstrated that an association exists between low light exposure to the sun, non-melanoma skin cancer and a lack of vitamin D synthesis. As vitamin D synthesis in the body depends on skin exposure to UVB radiation from the sun (wavelength, 290–320 nm), experimental measurements for this type of solar radiation are important. The present study analyzed data obtained from a laboratory investigating UV radiation from the sun at the University of Tarapacá (Arica, Chile), where systematic experimental UVB measurements had been performed using a calibrated biometer instrument since 2006. These data were compared with skin cancer data from the local population. The results demonstrated that the incidence of skin cancer systematically increased from 7.4 to 18.7 in men and from 10.0 to 21.7 in women between 2000 and 2006 in Arica, respectively; this increase may be due to multiple factors, including the lack of adequate levels of vitamin D in risk groups such as post-menopausal women and senior age. This marked increase may also be due to the high levels of UV radiation measured in this region throughout the year. However, it is not certain that the local population has adequate vitamin D levels, nor that their skin has been predominantly exposed to artificial light that does not allow adequate vitamin D synthesis. Thus, the current study presents the association between skin type IV, the time to induce solar erythema and the time required to produce 1,000 international units of vitamin D. PMID:26622830

  3. Ultraviolet light exposure, skin cancer risk and vitamin D production.

    PubMed

    Rivas, Miguel; Rojas, Elisa; Araya, María C; Calaf, Gloria M

    2015-10-01

    The danger of overexposure to solar ultraviolet radiation has been widely reviewed since the 1980s due to the depletion of the ozone layer. However, the benefits of mild exposure of the skin to ultraviolet (UV) light have not been widely investigated. Numerous reports have demonstrated that an association exists between low light exposure to the sun, non-melanoma skin cancer and a lack of vitamin D synthesis. As vitamin D synthesis in the body depends on skin exposure to UVB radiation from the sun (wavelength, 290-320 nm), experimental measurements for this type of solar radiation are important. The present study analyzed data obtained from a laboratory investigating UV radiation from the sun at the University of Tarapacá (Arica, Chile), where systematic experimental UVB measurements had been performed using a calibrated biometer instrument since 2006. These data were compared with skin cancer data from the local population. The results demonstrated that the incidence of skin cancer systematically increased from 7.4 to 18.7 in men and from 10.0 to 21.7 in women between 2000 and 2006 in Arica, respectively; this increase may be due to multiple factors, including the lack of adequate levels of vitamin D in risk groups such as post-menopausal women and senior age. This marked increase may also be due to the high levels of UV radiation measured in this region throughout the year. However, it is not certain that the local population has adequate vitamin D levels, nor that their skin has been predominantly exposed to artificial light that does not allow adequate vitamin D synthesis. Thus, the current study presents the association between skin type IV, the time to induce solar erythema and the time required to produce 1,000 international units of vitamin D.

  4. DNA endonuclease activities on psoralen plus ultraviolet light treated DNA

    SciTech Connect

    Lambert, M.W.; Clark, M.

    1986-03-01

    Activities of nuclear DNA endonucleases (Endos) from normal human lymphoblastoid cells on DNA treated with the DNA interstrand cross-linking agents 4,5'8-trimethyl psoralen (TMP) or 8-methoxypsoralen (MOP) plus long-wavelength (320-400 nm) ultraviolet light (UVA) were examined. Chromatin-associated DNA Endos were isolated from both cell lines and subjected to isoelectric focusing (IF). Each IF fraction was assayed for DNA Endo activity. Peaks of activity were pooled and assayed for activity on undamaged PM2 bacteriophage DNA and on PM2 DNA that had been treated with 15 ..mu..g/ml TMP or MOP in the dark and then exposed to UVA light. Unbound psoralen was removed by dialysis and a second dose of UVA light was given in order to increase the number of DNA cross-links. Two Endo activities were found which were active on TMP- and MOP-DNA: a major one, pI 4.6, which is also active on intercalated DNA, and a second, lesser one, pI 7.6, which is active on UVC (254 nm) light irradiated DNA. These results indicate that there are two different DNA Endos which act on both TMP- and MOP-treated DNA and that the major activity recognizes the intercalation of, and/or the cross-link produced by interaction of, psoralen with DNA.

  5. Geometrical gradients in the distribution of temperature and absorbed ultraviolet radiation in ocular tissues.

    PubMed

    Sliney, David H

    2002-01-01

    The geographical variations in the incidence of age-related ocular changes such as presbyopia and cataracts and diseases such as pterygium and droplet keratopathies have led to theories pointing to sunlight, ultraviolet radiation (UVR) exposure and ambient temperature as potential etiological factors. Some epidemiological evidence also points to an association of age-related macular degeneration to sunlight exposure. The actual distribution of sunlight exposure and the determination of temperature variations of different tissues within the anterior segment of the eye are difficult to assess. Of greatest importance are the geometrical factors that influence selective UVR exposures to different segments of the lens, cornea and retina. Studies show that the temperature of the lens and cornea varies by several degrees depending upon climate, and that the incidence of nuclear cataract incidence is greater in areas of higher ambient temperature (i.e., in the tropics). Likewise, sunlight exposure to local areas of the cornea, lens and retina varies greatly in different environments. However, epidemiological studies of the influence of environmental UVR in the development of cataract, pterygium, droplet keratopathies and age-related macular degeneration have produced surprisingly inconsistent findings. The lack of consistent results is seen to be due largely to either incomplete or erroneous estimates of outdoor UV exposure dose. Geometrical factors dominate the determination of UVR exposure of the eye. The degree of lid opening limits ocular exposure to rays entering at angles near the horizon. Clouds redistribute overhead UVR to the horizon sky. Mountains, trees and building shield the eye from direct sky exposure. Most ground surfaces reflect little UVR. The result is that highest UVR exposure occurs during light overcast where the horizon is visible and ground surface reflection is high. By contrast, exposure in a high mountain valley (lower ambient temperature) with

  6. Photosynthesis, Growth, and Ultraviolet Irradiance Absorbance of Cucurbita pepo L. Leaves Exposed to Ultraviolet-B Radiation (280-315 nm).

    PubMed

    Sisson, W B

    1981-01-01

    Net photosynthesis, growth, and ultraviolet (UV) radiation absorbance were determined for the first leaf of Cucurbita pepo L. exposed to two levels of UV-B irradiation and a UV-B radiation-free control treatment. Absorbance by extracted flavonoid pigments and other UV-B radiation-absorbing compounds from the first leaves increased with time and level of UV-B radiation impinging on leaf surfaces. Although absorbance of UV-B radiation by extracted pigments increased substantially, UV-B radiation attenuation apparently was insufficient to protect completely the photosynthetic apparatus or leaf growth processes. Leaf expansion was repressed by daily exposure to 1365 Joules per meter per day of biologically effective UV-B radiation but not by exposure to 660 Joules per meter per day. Photosynthesis measured through ontogenesis of the first leaf was depressed by both UV-B radiation treatments. Repression of photosynthesis by UV-B radiation was especially evident during the ontogenetic period of maximum photosynthetic activity.

  7. Photosynthesis, Growth, and Ultraviolet Irradiance Absorbance of Cucurbita pepo L. Leaves Exposed to Ultraviolet-B Radiation (280-315 nm) 1

    PubMed Central

    Sisson, William B.

    1981-01-01

    Net photosynthesis, growth, and ultraviolet (UV) radiation absorbance were determined for the first leaf of Cucurbita pepo L. exposed to two levels of UV-B irradiation and a UV-B radiation-free control treatment. Absorbance by extracted flavonoid pigments and other UV-B radiation-absorbing compounds from the first leaves increased with time and level of UV-B radiation impinging on leaf surfaces. Although absorbance of UV-B radiation by extracted pigments increased substantially, UV-B radiation attenuation apparently was insufficient to protect completely the photosynthetic apparatus or leaf growth processes. Leaf expansion was repressed by daily exposure to 1365 Joules per meter per day of biologically effective UV-B radiation but not by exposure to 660 Joules per meter per day. Photosynthesis measured through ontogenesis of the first leaf was depressed by both UV-B radiation treatments. Repression of photosynthesis by UV-B radiation was especially evident during the ontogenetic period of maximum photosynthetic activity. PMID:16661610

  8. Photosynthesis, growth, and ultraviolet irradiance absorbance of Cucurbita pepo L. leaves exposed to ultraviolet-B radiation (280 to 315 nm)

    SciTech Connect

    Sisson, W.B.

    1981-01-01

    Net photosynthesis, growth, and ultraviolet (uv) radiation absorbance were determined for the first leaf of Cucurbita pepo L. exposed to two levels of uv-B irradiation and a uv-B radiation-free control treatment. Absorbance by extracted flavonoid pigments and other uv-B radiation-absorbing compounds from the first leaves increased with time and level of uv-B radiation impinging on leaf surfaces. Although absorbance of uv-B radiation by extracted pigments increased substantially, uv-B radiation attenuation apparently was insufficient to protect completely the photosynthetic apparatus or leaf growth processes. Leaf expansion was repressed by daily exposure to 1365 Joules per meter per day of biologically effective uv-B radiation by not by exposure to 660 Joules per meter per day. Photosynthesis measured through ontogenesis of the first leaf was depressed by both uv-B radiation treatments. Repression of photosynthesis by uv-B radiation was especially evident during the ontogenetic period of maximum photosynthetic activity.

  9. Melanin photosensitizes ultraviolet light (UVC) DNA damage in pigmented cells

    SciTech Connect

    Huselton, C.A.; Hill, H.Z. )

    1990-01-01

    Melanins, pigments of photoprotection and camouflage, are very photoreactive and can both absorb and emit active oxygen species. Nevertheless, black skinned individuals rarely develop skin cancer and melanin is assumed to act as a solar screen. Since DNA is the target for solar carcinogenesis, the effect of melanin on Ultraviolet (UV)-induced thymine lesions was examined in mouse melanoma and carcinoma cells that varied in melanin content. Cells prelabeled with 14C-dThd were irradiated with UVC; DNA was isolated, purified, degraded to bases by acid hydrolysis and analyzed by HPLC. Thymine dimers were detected in all of the extracts of irradiated cells. Melanotic and hypomelanotic but not mammary carcinoma cell DNA from irradiated cells contained hydrophilic thymine derivatives. The quantity of these damaged bases was a function of both the UVC dose and the cellular melanin content. One such derivative was identified by gas chromatography-mass spectroscopy as thymine glycol. The other appears to be derived from thymine glycol by further oxidation during acid hydrolysis of the DNA. The finding of oxidative DNA damage in melanin-containing cells suggests that melanin may be implicated in the etiology of caucasian skin cancer, particularly melanoma. Furthermore, the projected decrease in stratospheric ozone could impact in an unanticipated deleterious manner on dark-skinned individuals.

  10. Melanin photosensitizes ultraviolet light (UVC) DNA damage in pigmented cells.

    PubMed

    Huselton, C A; Hill, H Z

    1990-01-01

    Melanins, pigments of photoprotection and camouflage, are very photoreactive and can both absorb and emit active oxygen species. Nevertheless, black skinned individuals rarely develop skin cancer and melanin is assumed to act as a solar screen. Since DNA is the target for solar carcinogenesis, the effect of melanin on Ultraviolet (UV)-induced thymine lesions was examined in mouse melanoma and carcinoma cells that varied in melanin content. Cells prelabeled with 14C-dThd were irradiated with UVC; DNA was isolated, purified, degraded to bases by acid hydrolysis and analyzed by HPLC. Thymine dimers were detected in all of the extracts of irradiated cells. Melanotic and hypomelanotic but not mammary carcinoma cell DNA from irradiated cells contained hydrophilic thymine derivatives. The quantity of these damaged bases was a function of both the UVC dose and the cellular melanin content. One such derivative was identified by gas chromatography-mass spectroscopy as thymine glycol. The other appears to be derived from thymine glycol by further oxidation during acid hydrolysis of the DNA. The finding of oxidative DNA damage in melanin-containing cells suggests that melanin may be implicated in the etiology of caucasian skin cancer, particularly melanoma. Furthermore, the projected decrease in stratospheric ozone could impact in an unanticipated deleterious manner on dark-skinned individuals.

  11. Does infrared or ultraviolet light damage the lens?

    PubMed Central

    Söderberg, P G; Talebizadeh, N; Yu, Z; Galichanin, K

    2016-01-01

    In daylight, the human eye is exposed to long wavelength ultraviolet radiation (UVR), visible radiation and short wavelength infrared radiation (IRR). Almost all the UVR and a fraction of the IRR waveband, respectively, left over after attenuation in the cornea, is absorbed in the lens. The time delay between exposure and onset of biological response in the lens varies from immediate-to-short-to-late. After exposure to sunlight or artificial sources, generating irradiances of the same order of magnitude or slightly higher, biological damage may occur photochemically or thermally. Epidemiological studies suggest a dose-dependent association between short wavelength UVR and cortical cataract. Experimental data infer that repeated daily in vivo exposures to short wavelength UVR generate photochemically induced damage in the lens, and that short delay onset cataract after UVR exposure is photochemically induced. Epidemiology suggests that daily high-intensity short wavelength IRR exposure of workers, is associated with a higher prevalence of age-related cataract. It cannot be excluded that this effect is owing to a thermally induced higher denaturation rate. Recent experimental data rule out a photochemical effect of 1090 nm in the lens but other wavelengths in the near IRR should be investigated. PMID:26768915

  12. Ultraviolet B light stimulates hornet activities - a review

    NASA Astrophysics Data System (ADS)

    Ishay, Jacob S.; Kirshboim, Shira

    2000-07-01

    For more than 30 years now, we have been gathering data on vespan activity in the field and laboratory under the influence of various factors. We found that light is most influential on the behaviour and activities of hornets (Hymenoptera, Vespinae); among various light wavelengths, the greatest influence was ascribed to the ultraviolet bandwidth (UVB). Prominent vespan activities outside their nest included digging, that is, the removal of soil from the nest, and we found this activity to take place at high noon, when the UV radiation, especially the UVB fraction, is maximal. In fact the digging activity of hornets was at times fully coordinated with the solar radiation, especially with the UVB portion of it, so that in daytime hours with diminished UV radiation, as in the morning or the afternoon, this activity and also flights outside the nest were accordingly curtailed, whereas at night there was no vespan flight at all. Under laboratory conditions, we found that hornets subjected to ether anaesthesia awaken faster when exposed to UV light than do control hornets left in the dark. In this connection, the exposure of pieces of hornet cuticle to UV light resulted in enhanced light absorption by the cuticle, but the absorption level reverted to normal after a period of rest in the dark. Tests for cuticular fluorescence after its irradiation with UVB light (290 nm) revealed a dominant emission in both UV and visible light. Furthermore, exposure of the cuticle of either live or dead hornets to light results in a photovoltaic effect which amplifies under UV irradiation. The hornet cuticle appears to behave like a semiconductor with traps and under the influence of light irradiation the electrical conductivity diminishes. The cuticle exposed to UV irradiation undergoes polarization, as do ferroelectric substances after being exposed to an electric field. The present paper summarizes the results of experiments and observations carried out on both live and dead hornets

  13. Tunnel junction enhanced nanowire ultraviolet light emitting diodes

    SciTech Connect

    Sarwar, A. T. M. Golam; May, Brelon J.; Deitz, Julia I.; Grassman, Tyler J.; McComb, David W.; Myers, Roberto C.

    2015-09-07

    Polarization engineered interband tunnel junctions (TJs) are integrated in nanowire ultraviolet (UV) light emitting diodes (LEDs). A ∼6 V reduction in turn-on voltage is achieved by the integration of tunnel junction at the base of polarization doped nanowire UV LEDs. Moreover, efficient hole injection into the nanowire LEDs leads to suppressed efficiency droop in TJ integrated nanowire LEDs. The combination of both reduced bias voltage and increased hole injection increases the wall plug efficiency in these devices. More than 100 μW of UV emission at ∼310 nm is measured with external quantum efficiency in the range of 4–6 m%. The realization of tunnel junction within the nanowire LEDs opens a pathway towards the monolithic integration of cascaded multi-junction nanowire LEDs on silicon.

  14. Developmental changes in the sensitivity of Volvox to ultraviolet light

    SciTech Connect

    Baran, G.J.; Huskey, R.J.

    1986-01-01

    The response of Volvox to ultraviolet irradiation was analyzed. Young individuals isolated from a synchronous culture were exposed to UV light (120 J/m2) and subjected to variable length periods of dark following irradiation. The major effect of the UV treatment was the inability of the gonidia present in the colonies at the time of irradiation to continue and complete the developmental program. Individuals show a heightened sensitivity to UV for a limited period immediately following inversion and are insensitive at other stages of development. The cytotoxic effect of UV during this interval is completely reversed by the immediate exposure to white light and is increased with longer periods of dark treatment prior to exposure to white light. The temporal profile of the sensitivity defines a smooth curve in which the maximal sensitivity occurs three hours after inversion. The response to higher doses of UV (up to 500 J/m2) is a nonlinear increase in cytotoxicity and is disproportionately greater in those individuals just prior to the period of maximal sensitivity than those later in development. The results suggest that Volvox has at least two pathways for the repair of UV damage and that one of these, the principal dark repair pathway, is temporarily deficient in the gonidia of young individuals.

  15. Ultraviolet light output of compact fluorescent lamps: comparison to conventional incandescent and halogen residential lighting sources.

    PubMed

    Nuzum-Keim, A D; Sontheimer, R D

    2009-05-01

    Patients with photosensitive dermatologic and systemic diseases often question the ultraviolet light (UVL) output of household lighting sources. Such individuals have increasing concern about potential UVL exposure from energy-efficient compact fluorescent lamps (CFL), as little data have been presented concerning their UVL output. The objective was to compare, via pilot study, the levels of ultraviolet A (UVA) and ultraviolet B (UVB) leak between residential lighting sources. Equivalent wattage CFL, incandescent and halogen bulbs were purchased from local retailers in Oklahoma City, Oklahoma, USA. The UVA and UVB outputs of these sources were measured under controlled conditions at 10, 25, 50, 100 and 150 cm away from the light source using an IL-1700 research radiometer equipped with UVA and UVB detectors. Negligible UVB and UVA was detected at 100 and 150 cm. Therefore, data were analysed from measurements at 10, 25 and 50 cm only. The results demonstrated UVA leak highest from incandescent and halogen bulbs, and UVB leak highest from CFL. The overall UVA/UVB leak was lowest from CFL shielded during the manufacturing process. In conclusion, patients with photosensitivity have choices depending on their relative risk from different UVL wavelength spectra. UVB exposure risk may be reduced the greatest by utilising CFL with manufacturer-provided shields.

  16. Preventing Eye Damage from the Sun's Ultraviolet Light: What Health Educators Should Teach.

    ERIC Educational Resources Information Center

    Memmer, Mary Kelly

    1989-01-01

    Health educators are in an ideal position to teach individuals about dangers from the sun's ultraviolet light and how to prevent damage to eyes. Ultraviolet light is described, eye pathology which can be caused by it is outlined, and protective eyewear is discussed. (IAH)

  17. Ultraviolet light (254 NM) inactivation of pathogens on foods and stainless steel surfaces

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Ultraviolet Light (254 nm) is a U.S. Food and Drug Administration approved nonthermal intervention technology that can be used for decontamination of food surfaces. In this study the use of Ultraviolet Light (UVC) at doses of 0.5 - 4.0 J/cm2 to inactivate a cocktail of Salmonella spp., Listeria mon...

  18. Ultraviolet light (254 NM) inactivation of pathogens on foods and stainless steel surfaces

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Ultraviolet Light (254 nm) is a U.S. Food and Drug Administration approved nonthermal intervention technology that can be used for decontamination of food surfaces. In this study the use of 254 nm. Ultraviolet Light (UV) at doses of 0.5 to 4.0 J/cm2 to inactivate Salmonella spp., Listeria monocytoge...

  19. Effects of exposure to ultraviolet light on the development of Rana pipiens, the northern leopard frog

    SciTech Connect

    Williams, J.J.; Wofford, H.W.

    1996-10-01

    The increase in ultraviolet light intensity levels due to ozone depletion recently has been linked to the decline in amphibian population. In this experiment, eggs and larvae of Rana pipiens were subjected to differing amounts of ultraviolet radiation to determine the effects of ultraviolet light on the development of amphibian tadpoles. The total length, length of body without tail, and maximum width of each specimen was recorded for a month of the tadpoles` development, including several measurements after the ultraviolet exposures were concluded. It was found that ultraviolet exposure significantly reduced the size of the organisms in comparison with the control group in all three measured areas. Ultraviolet radiation altered the health and appearance of the exposed organisms and was lethal at large amounts. This experiment showed that ultraviolet radiation could cause many problems in developing amphibians. By slowing their development and physically weakening predation, thus contributing to a decline in overall population levels.

  20. Determining ultraviolet absorbents in sunscreen products by combining direct injection with micelle collapse on-line preconcentration capillary electrophoresis.

    PubMed

    Hsiao, Wen-Yao; Jiang, Shiuh-Jen; Feng, Chia-Hsien; Wang, Shih-Wei; Chen, Yen-Ling

    2015-02-27

    The on-line preconcentration technique of analyte focusing by micelle collapse-micellar electrokinetic chromatography (AFMC-MEKC) was combined with direct injection without extraction to determine ultraviolet absorbents in sunscreen products. The stacking mechanism is based on the transport, release, and accumulation of analytes bound to micelle carriers that are collapsed into the micelle dilution zone. The following optimized conditions were determined: the running buffer was 10mM Tris buffer (pH 9.5) containing 60mM SDS, 7mM γ-CD and 20% ethanol; the SDS concentration was required to be slightly above the critical micelle concentration (cmc) value (7.4mM) in the sample matrix, which allowed the micelle dilution zone to form when voltage was applied; and finally, the sample was prepared in 100mM Tris buffer (pH 9.0) containing 7.5mM SDS and 20% (v/v) ethanol to provide sufficient resolution and to improve the sensitivity. Samples were injected at 0.5psi for 40s, and the separation voltage was set at 15kV for first 15min and then increased to 23kV to decrease the analysis time. The detection sensitivity for ultraviolet absorbents was enhanced by approximately 41-fold using AFMC-MEKC compared to conventional MEKC. The limit of detection (S/N=3) was 98nM for benzophenone-2 and benzophenone-4. The correlation of the regression curve was greater than 0.995. The relative error and relative standard deviation were lower than 9.94% with high precision and accuracy. The recoveries of nine ultraviolet absorbents in a homemade emulsion were between 95.08% and 104.57%. After optimization and validation, this AFMC-MEKC method combined with direct injection is considered to be established and successfully applicable to commercial sunscreen products.

  1. Development of ultraviolet nitride-based light emitting diodes

    NASA Astrophysics Data System (ADS)

    Katona, Thomas Matthew

    2003-10-01

    Deep ultraviolet light emitting diodes, with emission wavelengths shorter than 360 nm, have attracted interest due to their potential applications as replacement white light sources, in non-line of sight communication, for chemical and biological weapons detection, medical applications, water purification, and counterfeit detection. Light emitters in this wavelength range require AlGaN based active regions with increasing Al composition as the wavelength is decreased. High Al composition AlGaN based devices have been challenged by difficulty in growth, low electron and hole mobilities, and deep dopant levels resulting in low carrier concentrations. The combination of these factors has resulted in UV optoelectronic devices with quantum efficiency several orders of magnitude lower than their GaN/InGaN based visible counterparts. This work will details studies on alternative selective area growth techniques for dislocation reduction and the development of ultraviolet LEDs ranging from 292--340 nm. Lateral overgrowth of GaN on patterned Si (111) substrates was developed with the hope of developing seed material for bulk GaN growth. The effect of growth conditions on both the crystallographic wing tilt and crack density in the AlN/GaN films was studied. By controlling the lateral to vertical growth rate at the beginning of lateral overgrowth, the wing tilt can be effectively eliminated. We also demonstrate the first lateral overgrowth of AlN to create low threading dislocation density AlN template layers for optoelectronic device development. Deep UV quantum wells grown on this material were studied with cathodoluminescence to study the effect of dislocations on radiative recombination in deep UV devices. In addition to work on lateral overgrowth of GaN and AlN, 292, 340 nm LEDs were grown on AlN on sapphire and GaN on sapphire respectively. AlN strain relief interlayers were developed to prevent cracking of the 340 nm AlGaN based LEDs that were grown in tension on Ga

  2. Novel cylindrical illuminator tip for ultraviolet light delivery

    NASA Astrophysics Data System (ADS)

    Shangguan, HanQun; Haw, Thomas E.; Gregory, Kenton W.; Casperson, Lee W.

    1993-06-01

    The design, processing, and sequential testing of a novel cylindrical diffusing optical fiber tip for ultraviolet light delivery is described. This device has been shown to uniformly (+/- 15%) illuminate angioplasty balloons, 20 mm in length, that are used in an experimental photochemotherapeutic treatment of swine intimal hyperplasia. Our experiments show that uniform diffusing tips of < 400 micron diameter can be reliably constructed for this and other interstitial applications. Modeling results indicate that this design is scalable to smaller diameters. The diffusing tips are made by stripping the protective buffer and etching away the cladding over a length of 20 mm from the fiber tip and replacing it with a thin layer of optical epoxy mixed with Al2O3 powder. To improve the uniformity and ease of fabrication, we have evaluated a new device configuration where the tip is etched into a modified conical shape, and the distal end face is polished and then coated with an optically opaque epoxy. This is shown to uniformly scatter approximately 70% of the light launched into the fiber without forward transmission.

  3. Spectroscopic study of graphene oxide membranes exposed to ultraviolet light

    SciTech Connect

    Schwenzer, Birgit; Kaspar, Tiffany C.; Shin, Yongsoon; Gotthold, David W.

    2016-05-16

    Research on graphene oxide (GO) as anything but a precursor material for synthesizing graphene started to pick up in 20061,2 and was soon followed by a first report of freestanding GO membranes (also referred to as GO paper) from R. S. Ruoff’s group at Northwestern University.3 The first GO membranes were prepared by vacuum filtration. More recently, larger scale GO membranes have been prepared by tape casting4 and other methods.5 In step with the development of new fabrication techniques, GO membranes are now tested for a wide array of applications6 ranging from energy-related4,7 or biomedical8 applications to more conventional uses for filtration9 and dehumidification.10 For all these proposed and implemented applications it remains to be seen how sensitive each of them is with respect to chemical and physical changes of the GO membranes over time. In this study, we report the effects of UV exposure on 2D-hierarchically stacked (Fig. S1 in ESI†) GO membranes. Macroscopically observable changes, such as darkening and mechanical deformation, have been correlated to chemical changes at the molecular level through spectroscopic measurements. Not only do the results of this work offer insights into the stability of GO membranes under UV light, but the findings will enable researchers, who are studying the use of these materials for different applications, to better understand the shelf life and packaging requirements for GO membranes. Furthermore, our results demonstrate the feasibility of deep ultraviolet (DUV) photolithography for graphene oxide-based devices. This approach is readily scalable as opposed to previous reports on photolithographic patterned reduction of GO to graphene by AFM,11 electron-beam12 or with an extreme ultraviolet (λ = 46.9 nm) laser.13

  4. A synthetic light curve solution of the OAO-2 ultraviolet light curves of u Herculis

    NASA Technical Reports Server (NTRS)

    Eaton, J. A.

    1978-01-01

    OAO 2 ultraviolet photometry of the eclipsing binary u Her is reported and interpreted. The light curve of u Her is found to be intrinsically variable, the variable light curve is rectified, and the adjusted light and color curves are plotted. A simultaneous solution to three adjusted OAO 2 light curves (at respective wavelengths of 3320, 1910, and 1550 A) is obtained by using the Roche model. The results indicate that the system is semidetached if the gravity darkening of the secondary is not significantly larger than expected. It is suggested that the primary is responsible for the variable light curve, that the monochromatic albedo of the secondary is very low at short wavelengths, and that the depth of primary eclipse is strongly dependent on the primary's limb darkening.

  5. The Effect of Ultraviolet Light on the "Liquid Wood"

    NASA Astrophysics Data System (ADS)

    Dumitru, Nedelcu; Sabina, Zǎgan; Ticuta, Negreanu-Pirjol; Remus, Zǎgan; Constantin, Cǎrausu

    2014-08-01

    To preserve resources, the goal is to use biobased materials containing the maximum possible amount of renewable biomass-based derivatives to secure a sustainable future. Bioplastics, biocomposites, biological fibres and related biomaterials will serve as substitutes for materials and products traditionally made from petroleum resources. To support this need, in 1998, Fraunhofer Institute of Chemistry and Tecnaro GmbH Company (founded by Jurgen Pfitzer and Helmut Nagele in Germany) investigated and developed a new compound made of wood components that can be processed as a thermoplastic material. It is well known that bioplastic and biocomposite materials represent another important group of bio-materials that include plastics reinforced with natural fibers and wood-plastic composites (WPCs). The aim of this research is to identify the behavior of "Liquid Wood" after UV irradiation. The materials used were Arbofill Fichte, Arboblend V2 Nature and Arboform L, V3 Nature. The samples were obtained by injection and the experimental study plan followed the Taguchi method with six input parameters and two levels for each of them. Three samples from each material were tested in an ultraviolet environment using different time of exposure in order to establish the material characteristics. After the irradiation process the material did not turn to yellow, which suggests that the composition of the sample liquid timber inhibitors have stability and the number of α-carbonyl (C = O) groups is sufficiently low. After the graphs analyzing can be inferred relatively similar performance of the samples in the first stage both UV and the VIS, indicating that the activity is almost absent. In UV is clearly observed the peak amplitude (maximum absorbance) at different wavelengths (λ). So, in terms of peak intensity the samples follow the order: Arboform L, V3 Nature; Arbofill Fichte and Arboblend V2 Nature.

  6. All-Silicon Ultra-Broadband Infrared Light Absorbers

    PubMed Central

    Gorgulu, Kazim; Gok, Abdullah; Yilmaz, Mehmet; Topalli, Kagan; Bıyıklı, Necmi; Okyay, Ali K.

    2016-01-01

    Absorbing infrared radiation efficiently is important for critical applications such as thermal imaging and infrared spectroscopy. Common infrared absorbing materials are not standard in Si VLSI technology. We demonstrate ultra-broadband mid-infrared absorbers based purely on silicon. Broadband absorption is achieved by the combined effects of free carrier absorption, and vibrational and plasmonic absorption resonances. The absorbers, consisting of periodically arranged silicon gratings, can be fabricated using standard optical lithography and deep reactive ion etching techniques, allowing for cost-effective and wafer-scale fabrication of micro-structures. Absorption wavebands in excess of 15 micrometers (5–20 μm) are demonstrated with more than 90% average absorptivity. The structures also exhibit broadband absorption performance even at large angles of incidence (θ = 50°), and independent of polarization. PMID:27924933

  7. Feedback from Mass Outflows in Nearby Active Galactic Nuclei. I. Ultraviolet and X-Ray Absorbers

    NASA Astrophysics Data System (ADS)

    Crenshaw, D. M.; Kraemer, S. B.

    2012-07-01

    We present an investigation into the impact of feedback from outflowing UV and X-ray absorbers in nearby (z < 0.04) active galactic nuclei (AGNs). From studies of the kinematics, physical conditions, and variability of the absorbers in the literature, we calculate the possible ranges in the total mass outflow rate (\\dot{M}_{out}) and kinetic luminosity (L KE) for each AGN, summed over all of its absorbers. These calculations make use of values (or limits) for the radial locations of the absorbers determined from variability, excited-state absorption, and other considerations. From a sample of 10 Seyfert 1 galaxies with detailed photoionization models for their absorbers, we find that 7 have sufficient constraints on the absorber locations to determine \\dot{M}_{out} and L KE. For the low-luminosity AGN NGC 4395, these values are low, although we do not have sufficient constraints on the X-ray absorbers to make definitive conclusions. At least five of the six Seyfert 1s with moderate bolometric luminosities (L bol = 1043 - 1045 erg s-1) have mass outflow rates that are 10-1000 times the mass accretion rates needed to generate their observed luminosities, indicating that most of the mass outflow originates from outside the inner accretion disk. Three of these (NGC 4051, NGC 3516, and NGC 3783) have L KE in the range 0.5%-5% L bol, which is the range typically required by feedback models for efficient self-regulation of black hole and galactic bulge growth. At least two of the other three (NGC 5548, NGC 4151, and NGC 7469) have L KE >~ 0.1%L bol, although these values may increase if radial locations can be determined for more of the absorbers. We conclude that the outflowing UV and X-ray absorbers in moderate-luminosity AGNs have the potential to deliver significant feedback to their environments.

  8. Skin β-endorphin mediates addiction to ultraviolet light

    PubMed Central

    Fell, Gillian L.; Robinson, Kathleen C.; Mao, Jianren; Woolf, Clifford J.; Fisher, David E.

    2014-01-01

    SUMMARY Ultraviolet light is an established carcinogen yet evidence suggests that UV-seeking behavior has addictive features. Following UV exposure, epidermal keratinocytes synthesize Proopiomelanocortin that is processed to Melanocyte Stimulating Hormone, inducing tanning. We show that in rodents another POMC-derived peptide, β-endorphin, is coordinately synthesized in skin, elevating plasma levels after low-dose UV. Increases in pain-related thresholds are observed, and reversed by pharmacologic opioid antagonism. Opioid blockade also elicits withdrawal signs after chronic UV exposure. This effect was sufficient to guide operant behavioral choices to avoidance of opioid withdrawal (conditioned place aversion). These UV-induced nociceptive and behavioral effects were absent in β-endorphin knockout mice and in mice lacking p53-mediated POMC induction in epidermal keratinocytes. While primordial UV addiction, mediated by the hedonic action of β-endorphin and anhedonic effects of withdrawal, may theoretically have enhanced evolutionary vitamin D biosynthesis, it now may contribute to the relentless rise in skin cancer incidence in man. PMID:24949966

  9. Thermal mechanisms of laser marking in transparent polymers with light-absorbing microparticles

    NASA Astrophysics Data System (ADS)

    Zelenska, K. S.; Zelensky, S. E.; Poperenko, L. V.; Kanev, K.; Mizeikis, V.; Gnatyuk, V. A.

    2016-01-01

    Interaction of highly viscous polystyrene suspensions of light-absorbing microparticles with pulsed radiation of a Q-switched YAG:Nd3+ laser is investigated. Absorption of laser radiation by the suspended microparticles causes thermal decomposition (pyrolysis) of the polymer in the vicinity of the overheated particles. Laser-induced incandescence (LII) of light-absorbing microparticles under irradiation by a sequence of laser pulses is observed. The mechanism of laser marking includes formation of light-absorbing and scattering centers by accumulation of carbonaceous and gaseous products of pyrolysis.

  10. Synthesis and characterization of attosecond light vortices in the extreme ultraviolet

    PubMed Central

    Géneaux, R.; Camper, A.; Auguste, T.; Gobert, O.; Caillat, J.; Taïeb, R.; Ruchon, T.

    2016-01-01

    Infrared and visible light beams carrying orbital angular momentum (OAM) are currently thoroughly studied for their extremely broad applicative prospects, among which are quantum information, micromachining and diagnostic tools. Here we extend these prospects, presenting a comprehensive study for the synthesis and full characterization of optical vortices carrying OAM in the extreme ultraviolet (XUV) domain. We confirm the upconversion rules of a femtosecond infrared helically phased beam into its high-order harmonics, showing that each harmonic order carries the total number of OAM units absorbed in the process up to very high orders (57). This allows us to synthesize and characterize helically shaped XUV trains of attosecond pulses. To demonstrate a typical use of these new XUV light beams, we show our ability to generate and control, through photoionization, attosecond electron beams carrying OAM. These breakthroughs pave the route for the study of a series of fundamental phenomena and the development of new ultrafast diagnosis tools using either photonic or electronic vortices. PMID:27573787

  11. High performance near-ultraviolet flip-chip light-emitting diodes with distributed Bragg reflector

    NASA Astrophysics Data System (ADS)

    Choi, Il-Gyun; Jin, Geun-Mo; Park, Jun-Cheon; Jeon, Soo-Kun; Park, Eun-Hyun

    2015-09-01

    We have fabricated the near-ultraviolet (NUV) flip-chip (FC) light-emitting diodes (LEDs) with the high external quantum efficiency (EQE) using distributed Bragg reflectors (DBRs) and compared with conventional FC-LED using silver (Ag) reflector. Reflectance of Ag is very high (90 ~ 95 %) at visible spectrum region, but sharply decrease at NUV region. Therefore we used DBR composed of two different materials which have high-index contrast, such as TiO2 and SiO2. However, to achieve high-performance NUV flip-chip LEDs, we used Ta2O5 instead of TiO2 that absorbs lights of NUV region. Thus, we have designed a DBR composed of twenty pairs of Ta2O5 and SiO2 using optical coating design software. The DBR designed by our group achieves a reflectance of ~99 % in the NUV region (350 ~ 500 nm), which is much better than Ag reflector. Optical power is higher than the Ag-LED up to 22 % @ 390 nm.

  12. The eyes of the deep diving hooded seal (Cystophora cristata) enhance sensitivity to ultraviolet light

    PubMed Central

    Hogg, Chris; Neveu, Magella; Folkow, Lars; Stokkan, Karl-Arne; Hoh Kam, Jaimie; Douglas, Ron H.; Jeffery, Glen

    2015-01-01

    ABSTRACT The mammalian visual range is approximately 400–700 nm, although recent evidence suggests varying ultraviolet (UV) extensions in diverse terrestrial species. UV sensitivity may have advantages in the dim, blue light shifted environment experienced by submerged marine mammals. It may also be advantageous when seals are on land as UV is reflected by snow and ice but absorbed by fur, enhancing visual contrast. Here we show that the pelagic hooded seal (Cystophora cristata) has a highly UV permissive cornea and lens. Seals like other carnivores have a tapetum lucidum (TL) reflecting light back through the retina increasing sensitivity. The TL in this seal is unusual being white and covering almost the entire retina unlike that in other carnivores. Spectral reflectance from its surface selectively increases the relative UV/blue components >10 times than other wavelengths. Retinal architecture is consistent with a high degree of convergence. Enhanced UV from a large TL surface with a high degree of retinal convergence will increase sensitivity at a cost to acuity. UV electrophysiological retina responses were only obtained to dim, rod mediated stimuli, with no evidence of cone input. As physiological measurements of threshold sensitivity are much higher than those for psychophysical detection, these seals are likely to be more UV sensitive than our results imply. Hence, UV reflections from the TL will afford increased sensitivity in dim oceanic environments. PMID:25964660

  13. Light based anti-infectives: ultraviolet C irradiation, photodynamic therapy, blue light, and beyond.

    PubMed

    Yin, Rui; Dai, Tianhong; Avci, Pinar; Jorge, Ana Elisa Serafim; de Melo, Wanessa C M A; Vecchio, Daniela; Huang, Ying-Ying; Gupta, Asheesh; Hamblin, Michael R

    2013-10-01

    Owing to the worldwide increase in antibiotic resistance, researchers are investigating alternative anti-infective strategies to which it is supposed microorganisms will be unable to develop resistance. Prominent among these strategies, is a group of approaches which rely on light to deliver the killing blow. As is well known, ultraviolet light, particularly UVC (200-280 nm), is germicidal, but it has not been much developed as an anti-infective approach until recently, when it was realized that the possible adverse effects to host tissue were relatively minor compared to its high activity in killing pathogens. Photodynamic therapy is the combination of non-toxic photosensitizing dyes with harmless visible light that together produce abundant destructive reactive oxygen species (ROS). Certain cationic dyes or photosensitizers have good specificity for binding to microbial cells while sparing host mammalian cells and can be used for treating many localized infections, both superficial and even deep-seated by using fiber optic delivered light. Many microbial cells are highly sensitive to killing by blue light (400-470 nm) due to accumulation of naturally occurring photosensitizers such as porphyrins and flavins. Near infrared light has also been shown to have antimicrobial effects against certain species. Clinical applications of these technologies include skin, dental, wound, stomach, nasal, toenail and other infections which are amenable to effective light delivery.

  14. Light based anti-infectives: ultraviolet C irradiation, photodynamic therapy, blue light, and beyond

    PubMed Central

    Yin, Rui; Dai, Tianhong; Avci, Pinar; Jorge, Ana Elisa Serafim; de Melo, Wanessa CMA; Vecchio, Daniela; Huang, Ying-Ying; Gupta, Asheesh; Hamblin, Michael R

    2013-01-01

    Owing to the worldwide increase in antibiotic resistance, researchers are investigating alternative anti-infective strategies to which it is supposed microorganisms will be unable to develop resistance. Prominent among these strategies, is a group of approaches which rely on light to deliver the killing blow. As is well known, ultraviolet light, particularly UVC (200–280nm), is germicidal, but it has not been much developed as an anti-infective approach until recently, when it was realized that the possible adverse effects to host tissue were relatively minor compared to its high activity in killing pathogens. Photodynamic therapy is the combination of non-toxic photosensitizing dyes with harmless visible light that together produce abundant destructive reactive oxygen species (ROS). Certain cationic dyes or photosensitizers have good specificity for binding to microbial cells while sparing host mammalian cells and can be used for treating many localized infections, both superficial and even deep-seated by using fiber optic delivered light. Many microbial cells are highly sensitive to killing by blue light (400–470 nm) due to accumulation of naturally occurring photosensitizers such as porphyrins and flavins. Near infrared light has also been shown to have antimicrobial effects against certain species. Clinical applications of these technologies include skin, dental, wound, stomach, nasal, toenail and other infections which are amenable to effective light delivery. PMID:24060701

  15. Growth and fabrication of deep ultraviolet light emitting diodes on silicon carbide substrates

    NASA Astrophysics Data System (ADS)

    Moe, Craig Gunar

    Interest in deep ultraviolet (< 280 nm) emitters has developed rapidly in recent years, with its use in applications such as water purification, solid state lighting, and biochemical detection now being explored. The aluminum nitride and aluminum gallium nitride material systems are ideal for low cost, highly efficient emitters at these wavelengths, in the same manner that the InGaN LED revolutionized light emitters in the blue, green, and near-ultraviolet wavelengths. While the work to date on such devices have made use of sapphire as a substrate for epitaxial growth, silicon carbide has significant advantages including ease of growth and manufacture, reproducibility, and the potential for fewer dislocations in the material. This work follows the development of AlN and high-composition AlGaN films on SiC to a sufficient quality for emitter applications. A comprehensive examination of the AlN nucleation and buffer layers led to dislocation densities in the low 109cm-2. An extensive study of the n- and p-type doping of AlxGa 1-xN (x > 0.5) was undertaken to develop highly conductive material. The internal quantum efficiency of the quantum well region was significantly improved through modified growth conditions and precursor selection, and a device fabrication process was developed to obtain low turn-on voltages below 5 V and reliable device performance for over 100 hours of use. Careful thermal management of the devices through novel mask designs and improvement in packaging allowed for significant advances in light extraction, resulting in high-power LED emission at 280 nm. Packaged dies exhibited powers as high as 52 muW at 20 mA and 0.24 mW at 100 mA. The greatest obstacle to high external quantum efficiency in these devices is the absorbing nature SiC substrate. This has been successfully mitigated through two different techniques. First, distributed Bragg reflectors consisting of AlGaN/AlN stacks have been developed, with reflectivities greater than 80% at 275

  16. Changes induced by ozone and ultraviolet light in type I collagen. Bovine Achilles tendon collagen versus rat tail tendon collagen.

    PubMed

    Fujimori, E

    1985-10-15

    High-molecular-mass aggregates were made soluble from insoluble collagens of bovine Achilles tendon and rat tail tendon by limited thermal hydrolysis. These polymeric collagen aggregates were cross-linked by 390-nm-fluorescent 3-hydroxy-pyridinium residues (excited at 325 nm) in the former tendon and by unknown non-fluorescent residues in the latter. With the solubilized insoluble-collagens from both tendons, as well as with acid-soluble collagen from rat tail tendon, other 350-385-nm fluorescence intensities (excited at 300 nm) were found to be higher in monomeric chains than in dimeric and polymeric chains. Low levels of ozone inhibited fibril formation of acid-soluble collagen particularly from young rat tail tendon, reacting with tyrosine residues and the 350-385-nm fluorophores. Aldehyde groups, involved in cross-linking, were not effectively modified by ozone. beta-Components (alpha-chain dimers) were not efficiently dissociated even by higher doses of ozone compared to gamma-components (alpha-chain trimers). Polymeric chain aggregates from bovine Achilles tendon collagen, whose 3-hydroxy-pyridinium cross-links are cleaved by ozone, were more readily dissociated by ozone than those from rat tail tendon collagen. Ultraviolet (300-nm) light, which destroyed the 350-385-nm fluorophores, inhibited fibril formation less effectively than ultraviolet (275-nm) light, which is absorbed by tyrosine residues, and did not dissociate collagen polymers from rat tail tendon. On the other hand, ultraviolet (320-nm) light, absorbed by 3-hydroxy-pyridinium cross-links which were rapidly photolyzed, partially dissociated polymeric collagen aggregates from bovine Achilles tendon after subsequent heating.

  17. Two chemically distinct light-absorbing pools of urban organic aerosols: A comprehensive multidimensional analysis of trends.

    PubMed

    Paula, Andreia S; Matos, João T V; Duarte, Regina M B O; Duarte, Armando C

    2016-02-01

    The chemical and light-absorption dynamics of organic aerosols (OAs), a master variable in the atmosphere, have yet to be resolved. This study uses a comprehensive multidimensional analysis approach for exploiting simultaneously the compositional changes over a molecular size continuum and associated light-absorption (ultraviolet absorbance and fluorescence) properties of two chemically distinct pools of urban OAs chromophores. Up to 45% of aerosol organic carbon (OC) is soluble in water and consists of a complex mixture of fluorescent and UV-absorbing constituents, with diverse relative abundances, hydrophobic, and molecular weight (Mw) characteristics between warm and cold periods. In contrast, the refractory alkaline-soluble OC pool (up to 18%) is represented along a similar Mw and light-absorption continuum throughout the different seasons. Results suggest that these alkaline-soluble chromophores may actually originate from primary OAs sources in the urban site. This work shows that the comprehensive multidimensional analysis method is a powerful and complementary tool for the characterization of OAs fractions. The great diversity in the chemical composition and optical properties of OAs chromophores, including both water-soluble and alkaline-soluble OC, may be an important contribution to explain the contrasting photo-reactivity and atmospheric behavior of OAs.

  18. Ultraviolet absorbance as a proxy for total dissolved mercury in streams

    USGS Publications Warehouse

    Dittman, J.A.; Shanley, J.B.; Driscoll, C.T.; Aiken, G.R.; Chalmers, A.T.; Towse, J.E.

    2009-01-01

    Stream water samples were collected over a range of hydrologic and seasonal conditions at three forested watersheds in the northeastern USA. Samples were analyzed for dissolved total mercury (THgd), DOC concentration and DOC composition, and UV254 absorbance across the three sites over different seasons and flow conditions. Pooling data from all sites, we found a strong positive correlation of THgd to DOC (r2 = 0.87), but progressively stronger correlations of THgd with the hydrophobic acid fraction (HPOA) of DOC (r2 = 0.91) and with UV254 absorbance (r2 = 0.92). The strength of the UV254 absorbance-THgd relationship suggests that optical properties associated with dissolved organic matter may be excellent proxies for THgd concentration in these streams. Ease of sample collection and analysis, the potential application of in-situ optical sensors, and the possibility for intensive monitoring over the hydrograph make this an effective, inexpensive approach to estimate THgd flux in drainage waters. ?? 2009 Elsevier Ltd.

  19. Light scattering by absorbing hexagonal ice crystals in cirrus clouds.

    PubMed

    Zhang, J; Xu, L

    1995-09-01

    An improved ray-optics theory for single scattering and polarization of hexagonal columns and plates randomly oriented in space has been developed by considering absorption and by using the Chebyshev solution for diffraction integrals. The vector-tracing method and statistics technique of random sampling are employed. The equivalent forms of Snell's law and Fresnel formulas for absorbing ice crystals are derived, and two equivalent optical constants, m' and m″, are obtained. Comparison is made of the computed results of our model and the Takano and Liou model for asymmetry factors, single-scattering albedos, and scattering phase matrix elements. Some characteristics of our model are discussed, and these analyses demonstrate that our ray-optics model is practical and much improved.

  20. Soluble, light-absorbing species in snow at Barrow, Alaska

    NASA Astrophysics Data System (ADS)

    Beine, Harry; Anastasio, Cort; Esposito, Giulio; Patten, Kelley; Wilkening, Elizabeth; Domine, Florent; Voisin, Didier; Barret, Manuel; Houdier, Stephan; Hall, Sam

    2011-07-01

    As part of the international multidisciplinary Ocean - Atmosphere - Sea Ice - Snowpack (OASIS) program we analyzed more than 500 terrestrial (melted) snow samples near Barrow, AK between February and April 2009 for light absorption, as well as H2O2 and inorganic anion concentrations. For light absorption in the photochemically active region (300-450 nm) of surface snows, H2O2 and NO3- make minor contributions (combined < 9% typically), while HUmic LIke Substances (HULIS) and unknown chromophores each account for approximately half of the total absorption. We have identified four main sources for our residual chromophores (i.e., species other than H2O2 or NO3-): (1) vegetation and organic debris impact mostly the lowest 20 cm of the snowpack, (2) marine inputs, which are identified by high Cl- and SO42- contents, (3) deposition of diamond dust to surface snow, and (4) gas-phase exchange between the atmosphere and surface snow layers. The snow surfaces, and accompanying chromophore concentrations, are strongly modulated by winds and snowfall at Barrow. However, even with these physical controls on light absorption, we see an overall decline of light absorption in near-surface snow during the 7 weeks of our campaign, likely due to photo-bleaching of chromophores. While HULIS and unknown chromophores dominate light absorption by soluble species in Barrow snow, we know little about the photochemistry of these species, and thus we as a community are probably overlooking many snowpack photochemical reactions.

  1. Differential ultraviolet-visible absorbance spectra for characterizing metal ions binding onto extracellular polymeric substances in different mixed microbial cultures.

    PubMed

    Yin, Cuiqin; Meng, Fangang; Meng, Yabing; Chen, Guang-Hao

    2016-09-01

    Ultraviolet-visible (UV-vis) absorbance spectra was adopted to quantify the binding of major metal ions (e.g., Na(I), Ca((II)), Fe(III), Cu(II), and Pb(II)) on extracellular polymeric substances (EPSs) extracted from different mixed cultures. The results showed that the differential absorbance spectra (DAS) provided discernible features for revealing the changes in optical properties of EPSs induced by metals, i.e., the intensity of DAS increased largely with incrementally increased metal concentrations (Fe(III), Cu(II), and Pb(II)). It can be assumed attributable to the changes in the conformations and inter-chromophores of the EPS biomolecules. In addition, the changes in spectral parameters of DSlope325-375 (spectral slope in the range of wavelengths 325-375 nm) and DA300 (differential absorbance at 300 nm) were found to be closely related to the amounts of metals bound onto all extracted EPSs, particularly for Fe(III) and Cu(II). The decreased SR (the ratio of slope275-295 to slope350-400) of the EPS solutions after dosage of metals suggested increased molecular weight or size of the EPS biomolecules. Deconvolution of the DAS yielded six Gaussian bands, which were present in all of the EPS samples with various metals. Moreover, the relative contributions of different Gaussian bands in the DAS were determined by the nature of EPS-metal ions interactions good correlated with the covalent-bonding index. This study concluded that DAS and selected spectral parameters (DA300, DSlope325-375 and SR) can be used to successfully characterize the binding of metals onto EPS at environmentally relevant concentrations.

  2. Absorbance Based Light Emitting Diode Optical Sensors and Sensing Devices

    PubMed Central

    O'Toole, Martina; Diamond, Dermot

    2008-01-01

    The ever increasing demand for in situ monitoring of health, environment and security has created a need for reliable, miniaturised sensing devices. To achieve this, appropriate analytical devices are required that possess operating characteristics of reliability, low power consumption, low cost, autonomous operation capability and compatibility with wireless communications systems. The use of light emitting diodes (LEDs) as light sources is one strategy, which has been successfully applied in chemical sensing. This paper summarises the development and advancement of LED based chemical sensors and sensing devices in terms of their configuration and application, with the focus on transmittance and reflectance absorptiometric measurements. PMID:27879829

  3. NANOSTRUCTURED HIGH PERFORMANCE ULTRAVIOLET AND BLUE LIGHT EMITTING DIODES FOR SOLID STATE LIGHTING

    SciTech Connect

    Arto V. Nurmikko; Jung Han

    2004-10-01

    We report on research results in this project which synergize advanced material science approaches with fundamental optical physics concepts pertaining to light-matter interaction, with the goal of solving seminal problems for the development of very high performance light emitting diodes (LEDs) in the blue and near ultraviolet for Solid State Lighting applications. Accomplishments in the first 12 month contract period include (1) new means of synthesizing zero- and one-dimensional GaN nanostructures, (2) establishment of the building blocks for making GaN-based microcavity devices, and (3) demonstration of top-down approach to nano-scale photonic devices for enhanced spontaneous emission and light extraction. These include a demonstration of eight-fold enhancement of the external emission efficiency in new InGaN QW photonic crystal structures. The body of results is presented in this report shows how a solid foundation has been laid, with several noticeable accomplishments, for innovative research, consistent with the stated milestones.

  4. 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.

  5. Light-induced pyroelectric effect as an effective approach for ultrafast ultraviolet nanosensing.

    PubMed

    Wang, Zhaona; Yu, Ruomeng; Pan, Caofeng; Li, Zhaoling; Yang, Jin; Yi, Fang; Wang, Zhong Lin

    2015-09-25

    Zinc oxide is potentially a useful material for ultraviolet detectors; however, a relatively long response time hinders practical implementation. Here by designing and fabricating a self-powered ZnO/perovskite-heterostructured ultraviolet photodetector, the pyroelectric effect, induced in wurtzite ZnO nanowires on ultraviolet illumination, has been utilized as an effective approach for high-performance photon sensing. The response time is improved from 5.4 s to 53 μs at the rising edge, and 8.9 s to 63 μs at the falling edge, with an enhancement of five orders in magnitudes. The specific detectivity and the responsivity are both enhanced by 322%. This work provides a novel design to achieve ultrafast ultraviolet sensing at room temperature via light-self-induced pyroelectric effect. The newly designed ultrafast self-powered ultraviolet nanosensors may find promising applications in ultrafast optics, nonlinear optics, optothermal detections, computational memories and biocompatible optoelectronic probes.

  6. Light-induced pyroelectric effect as an effective approach for ultrafast ultraviolet nanosensing

    NASA Astrophysics Data System (ADS)

    Wang, Zhaona; Yu, Ruomeng; Pan, Caofeng; Li, Zhaoling; Yang, Jin; Yi, Fang; Wang, Zhong Lin

    2015-09-01

    Zinc oxide is potentially a useful material for ultraviolet detectors; however, a relatively long response time hinders practical implementation. Here by designing and fabricating a self-powered ZnO/perovskite-heterostructured ultraviolet photodetector, the pyroelectric effect, induced in wurtzite ZnO nanowires on ultraviolet illumination, has been utilized as an effective approach for high-performance photon sensing. The response time is improved from 5.4 s to 53 μs at the rising edge, and 8.9 s to 63 μs at the falling edge, with an enhancement of five orders in magnitudes. The specific detectivity and the responsivity are both enhanced by 322%. This work provides a novel design to achieve ultrafast ultraviolet sensing at room temperature via light-self-induced pyroelectric effect. The newly designed ultrafast self-powered ultraviolet nanosensors may find promising applications in ultrafast optics, nonlinear optics, optothermal detections, computational memories and biocompatible optoelectronic probes.

  7. Effect of ultraviolet-absorbing vinyl film on organophosphorus insecticides dichlorvos and fenitrothion residues in spinach.

    PubMed

    Amano, Shoko; Katami, Takeo; Shibamoto, Takayuki

    2002-07-01

    Dichlorvos and fenitrothion residues found in spinach grown in greenhouse covered either by regular vinyl film or UV-absorbing vinyl film (UV-A) were analyzed by gas chromatography. After one day, dichlorvos residues in spinach covered with regular vinyl film and UV-A degraded by 97% and 80%, respectively, and degraded 100% after three days covered with regular vinyl film and six days covered with UV-A. After three days, fenitrothion residue in spinach covered with regular vinyl film degraded by 72% and then by 97% after six days; residue in spinach covered with UV-A degraded by 50% after three days and by 95% after six days. These results indicate that UV-A used to prevent the occurrence of insects and fungi in greenhouses reduced the degradation rates of dichlorvos and fenitrothion.

  8. Enhancing Localized Evaporation through Separated Light Absorbing Centers and Scattering Centers.

    PubMed

    Zhao, Dengwu; Duan, Haoze; Yu, Shengtao; Zhang, Yao; He, Jiaqing; Quan, Xiaojun; Tao, Peng; Shang, Wen; Wu, Jianbo; Song, Chengyi; Deng, Tao

    2015-11-26

    This report investigates the enhancement of localized evaporation via separated light absorbing particles (plasmonic absorbers) and scattering particles (polystyrene nanoparticles). Evaporation has been considered as one of the most important phase-change processes in modern industries. To improve the efficiency of evaporation, one of the most feasible methods is to localize heat at the top water layer rather than heating the bulk water. In this work, the mixture of purely light absorptive plasmonic nanostructures such as gold nanoparticles and purely scattering particles (polystyrene nanoparticles) are employed to confine the incident light at the top of the solution and convert light to heat. Different concentrations of both the light absorbing centers and the light scattering centers were evaluated and the evaporation performance can be largely enhanced with the balance between absorbing centers and scattering centers. The findings in this study not only provide a new way to improve evaporation efficiency in plasmonic particle-based solution, but also shed lights on the design of new solar-driven localized evaporation systems.

  9. Enhancing Localized Evaporation through Separated Light Absorbing Centers and Scattering Centers

    PubMed Central

    Zhao, Dengwu; Duan, Haoze; Yu, Shengtao; Zhang, Yao; He, Jiaqing; Quan, Xiaojun; Tao, Peng; Shang, Wen; Wu, Jianbo; Song, Chengyi; Deng, Tao

    2015-01-01

    This report investigates the enhancement of localized evaporation via separated light absorbing particles (plasmonic absorbers) and scattering particles (polystyrene nanoparticles). Evaporation has been considered as one of the most important phase-change processes in modern industries. To improve the efficiency of evaporation, one of the most feasible methods is to localize heat at the top water layer rather than heating the bulk water. In this work, the mixture of purely light absorptive plasmonic nanostructures such as gold nanoparticles and purely scattering particles (polystyrene nanoparticles) are employed to confine the incident light at the top of the solution and convert light to heat. Different concentrations of both the light absorbing centers and the light scattering centers were evaluated and the evaporation performance can be largely enhanced with the balance between absorbing centers and scattering centers. The findings in this study not only provide a new way to improve evaporation efficiency in plasmonic particle-based solution, but also shed lights on the design of new solar-driven localized evaporation systems. PMID:26606898

  10. Enhanced light extraction in III-nitride ultraviolet photonic crystal light-emitting diodes

    NASA Astrophysics Data System (ADS)

    Shakya, J.; Kim, K. H.; Lin, J. Y.; Jiang, H. X.

    2004-07-01

    III-nitride photonic crystal (PC) ultraviolet (UV) light-emitting diodes (LEDs) were fabricated. Triangular arrays of the PCs with different diameters/periodicities were patterned using electron-beam lithography and inductively coupled plasma dry etching. The optical power output of LEDs was enhanced by a factor of 2.5 due to PC formation. It was observed that the optical enhancement factor depends strongly on the lattice constant and hole size of the PCs. The achievement of nitride PCs is expected to benefit many applications of III-nitride optoelectronics, particularly for the improvement of extraction efficiency in III-nitride deep-UV emitters (λ <340nm), which are crucial for many important applications, but presently have a very low quantum efficiency.

  11. Nanostructured High Performance Ultraviolet and Blue Light Emitting Diodes for Solid State Lighting

    SciTech Connect

    Arto V. Nurmikko; Jung Han

    2005-09-30

    We report on research results in this project which synergize advanced material science approaches with fundamental optical physics concepts pertaining to light-matter interaction, with the goal of solving seminal problems for the development of very high performance light emitting diodes (LEDs) in the blue and near ultraviolet for Solid State Lighting applications. Accomplishments in the second 12 month contract period include (i) new means of synthesizing AlGaN and InN quantum dots by droplet heteroepitaxy, (ii) synthesis of AlGaInN nanowires as building blocks for GaN-based microcavity devices, (iii) progress towards direct epitaxial alignment of the dense arrays of nanowires, (iv) observation and measurements of stimulated emission in dense InGaN nanopost arrays, (v) design and fabrication of InGaN photonic crystal emitters, and (vi) observation and measurements of enhanced fluorescence from coupled quantum dot and plasmonic nanostructures. The body of results is presented in this report shows how a solid foundation has been laid, with several noticeable accomplishments, for innovative research, consistent with the stated milestones.

  12. Nanostructured High Performance Ultraviolet and Blue Light Emitting Diodes for Solid State Lighting

    SciTech Connect

    Arto V. Nurmikko; Jung Han

    2007-03-31

    We report on research results in this project which synergize advanced material science approaches with fundamental optical physics concepts pertaining to light-matter interaction, with the goal of solving seminal problems for the development of very high performance light emitting diodes (LEDs) in the blue and near ultraviolet for Solid State Lighting applications. Accomplishments in the duration of the contract period include (i) new means of synthesizing AlGaN and InN quantum dots by droplet heteroepitaxy, (ii) synthesis of AlGaInN nanowires as building blocks for GaN-based microcavity devices, (iii) progress towards direct epitaxial alignment of the dense arrays of nanowires, (iv) observation and measurements of stimulated emission in dense InGaN nanopost arrays, (v) design and fabrication of InGaN photonic crystal emitters, and (vi) observation and measurements of enhanced fluorescence from coupled quantum dot and plasmonic nanostructures. The body of results is presented in this report shows how a solid foundation has been laid, with several noticeable accomplishments, for innovative research, consistent with the stated milestones.

  13. On seeing yellow: the case for, and against, short-wavelength light-absorbing intraocular lenses.

    PubMed

    Simunovic, Matthew P

    2012-07-01

    The normal human crystalline lens absorbs UV and short-wavelength visible electromagnetic radiation. Early intraocular lenses (IOLs) permitted the transmission of such radiation to the retina following cataract extraction. Experimental studies of the absorption profile of the crystalline lens and animal studies demonstrating the deleterious effects of short-wavelength radiation on the retina led to the development of UV-absorbing, and later, short-wavelength light-absorbing (SLA) IOLs. Short-wavelength light-absorbing IOLs were designed to mimic the absorption properties of the normal crystalline lens by absorbing some short-wavelength light in addition to UV radiation; however, debate continues regarding the relative merits of such lenses over UV-absorbing IOLs. Advocates of SLA IOLs suggest that they may theoretically offer increased photoprotection and decreased glare sensitivity and draw on in vitro, animal, and limited clinical studies that infer possible benefits. Detractors suggest that there is no direct evidence supporting a role for SLA IOLs in preventing retinal dysfunction in humans and suggest that they may have negative effects on color perception, scotopic vision, and circadian rhythms. This article examines the theoretical and empirical evidence for, and against, such lenses.

  14. Canine cancer screening via ultraviolet absorbance and fluorescence spectroscopy of serum proteins

    NASA Astrophysics Data System (ADS)

    Dickerson, Bryan D.; Geist, Brian L.; Spillman, William B., Jr.; Robertson, John L.

    2007-11-01

    A cost-effective optical cancer screening and monitoring technique was demonstrated in a pilot study of canine serum samples and was patented for commercialization. Compared to conventional blood chemistry analysis methods, more accurate estimations of the concentrations of albumin, globulins, and hemoglobin in serum were obtained by fitting the near UV absorbance and photoluminescence spectra of diluted serum as a linear combination of component reference spectra. Tracking these serum proteins over the course of treatment helped to monitor patient immune response to carcinoma and therapy. For cancer screening, 70% of dogs with clinical presentation of cancer displayed suppressed serum hemoglobin levels (below 20 mg/dL) in combination with atypical serum protein compositions, that is, albumin levels outside of a safe range (from 4 to 8 g/dL) and globulin levels above or below a more normal range (from 1.7 to 3.7 g/dL). Of the dogs that met these criteria, only 20% were given a false positive label by this cancer screening test.

  15. Lidar remote sensing of laser-induced incandescence on light absorbing particles in the atmosphere.

    PubMed

    Miffre, Alain; Anselmo, Christophe; Geffroy, Sylvain; Fréjafon, Emeric; Rairoux, Patrick

    2015-02-09

    Carbon aerosol is now recognized as a major uncertainty on climate change and public health, and specific instruments are required to address the time and space evolution of this aerosol, which efficiently absorbs light. In this paper, we report an experiment, based on coupling lidar remote sensing with Laser-Induced-Incandescence (LII), which allows, in agreement with Planck's law, to retrieve the vertical profile of very low thermal radiation emitted by light-absorbing particles in an urban atmosphere over several hundred meters altitude. Accordingly, we set the LII-lidar formalism and equation and addressed the main features of LII-lidar in the atmosphere by numerically simulating the LII-lidar signal. We believe atmospheric LII-lidar to be a promising tool for radiative transfer, especially when combined with elastic backscattering lidar, as it may then allow a remote partitioning between strong/less light absorbing carbon aerosols.

  16. A role for calcium hydroxide and dolomite in water: acceleration of the reaction under ultraviolet light.

    PubMed

    Nagase, Hiroyasu; Tsujino, Hidekazu; Kurihara, Daisuke; Saito, Hiroshi; Kawase, Masaya

    2014-04-01

    Organic environmental pollutants are now being detected with remarkably high frequency in the aquatic environment. Photodegradation by ultraviolet light is sometimes used as a method for removing organic chemicals from water; however, this method is relatively inefficient because of the low degradation rates involved, and more efficient methods are under development. Here we show that the removal of various organic pollutants can be assisted by calcined dolomite in aqueous solution under irradiation with ultraviolet light. It was possible to achieve substantial removal of bisphenol A, chlorophenols, alkylphenols, 1-naphthol and 17β-estradiol. The major component of dolomite responsible for the removal was calcium hydroxide. Our results demonstrate that the use of calcium hydroxide with ultraviolet light irradiation can be a very effective method of rapidly removing organic environmental pollutants from water. This is a new role for calcium hydroxide and dolomite in water treatment.

  17. Effect of ultraviolet light on mechanical properties of Kevlar 49 composites

    SciTech Connect

    Larsson, F.

    1986-01-01

    The relationship betwen specimen thickness and tensile strength in Kevlar 49 composites following exposure to ultraviolet light is investigated. Specimens of 0.13, 0.25, and 0.50 mm thickness molded from one, two, and four layers of Fiberdux 914k-49-5 prepreg are exposed to ultraviolet light in a Spectrotest apparatus, which has a low pressure xenon burner with a spectral range of 0.29-0.60 microns, for 500 and 1000 hours. The tensile stiffness and tensile strength data reveal that the ultraviolet light caused a decrease in the tensile strength and tensile retention of the 0.13 mm (1 ply) specimen; however, the 0.25 mm (2 plies) and 0.50 mm (4 plies) specimens, and the initial tensile elastic modulus for each specimen are unaffected by the exposure.

  18. Reactivation of latent herpes simplex virus infection by ultraviolet light: a human model

    SciTech Connect

    Perna, J.J.; Mannix, M.L.; Rooney, J.F.; Notkins, A.L.; Straus, S.E.

    1987-09-01

    Infection with herpes simplex virus often results in a latent infection of local sensory ganglia and a disease characterized by periodic viral reactivation and mucocutaneous lesions. The factors that trigger reactivation in humans are still poorly defined. In our study, five patients with documented histories of recurrent herpes simplex virus infection on the buttocks or sacrum were exposed to three times their minimal erythema dose of ultraviolet light. Site-specific cutaneous herpes simplex virus infection occurred at 4.4 +/- 0.4 days after exposure to ultraviolet light in 8 of 13 attempts at reactivation. We conclude that ultraviolet light can reactivate herpes simplex virus under experimentally defined conditions. This model in humans should prove useful in evaluating the pathophysiology and prevention of viral reactivation.

  19. Monte Carlo Simulation of Optical Properties of Phosphor-Screened Ultraviolet Light in a White Light-Emitting Device

    NASA Astrophysics Data System (ADS)

    Chang, Chien C.; Chern, Ruey-Lin; Chang, C. Chung; Chu, Chin-Chou; Chi, Jim Y.; Su, Jung-Chieh; Chan, I-Min; Wang, Jih-Fu Trevor

    2005-08-01

    In this paper, we study the optical properties of phosphor-screened ultraviolet light emitted by a quantum well through a chamber. The chamber contains randomly distributed red, blue and green phosphors, and is top-covered with a layer of omnidirectional photonic bandgap material. A Monte Carlo ray tracing method is developed to model the absorption, reflection and transmission for the excited radiation of the ultraviolet light as well as the visible light by the individual phosphor particles. The efficiency of emitting white light by synthesizing the visible light through the top substrate is investigated with respect to the weight ratio, the size of phosphor particles, the dimension of the chamber and the reflectivity of the side wall and the bottom substrate.

  20. Recording of individual identification information on dental prostheses using fluorescent material and ultraviolet light.

    PubMed

    Naito, Yoshihito; Meinar, Ashrin N; Iwawaki, Yuki; Kashiwabara, Toshiya; Goto, Takaharu; Ito, Teruaki; Sakuma, Tetsuro; Ichikawa, Tetsuo

    2013-01-01

    The placement of individual identification on a prosthesis is very important for forensic dentistry and traceability. This article describes the unique naming/labeling of dentures with information for individual identification using a method in which information is invisible under natural light but visible under ultraviolet light-emitting diode/black light exposure. The use of laser beam machining with this method will enable the recording of a large amount of information.

  1. Use of an ultraviolet light at point-of-dispense faucet to eliminate Pseudomonas aeruginosa.

    PubMed

    Gerba, Charles P

    2015-05-01

    Tap water is believed to be a significant source of Pseudomonas aeruginosa in health care environments. This study evaluated an ultraviolet (UV) light point-of-dispense water treatment system for control of P aeruginosa. No P aeruginosa was detected in 30 different water dispensers in which the UV light device had been operating for 1-34 months. In comparison, P aeruginosa was found in other taps that did not feature this UV light system.

  2. Light-Absorbing Carbonaceous Particles: Chemical Composition and Its Implications for Direct Climate Forcing

    NASA Astrophysics Data System (ADS)

    Hemming, B. L.; Henze, D. K.; Akhtar, F.; Pinder, R. W.; Loughlin, D. H.

    2012-12-01

    Carbonaceous particles are understood to play a substantial role in direct climate forcing, but current estimates of this effect depend on very simple assumptions concerning the light absorbing properties of the materials from these particles are formed. The practice, to date is to classify all black (graphitic, combustion-derived) carbon as having a single mass absorption coefficient, with all other carbon consider only slightly- or completely non-absorbing. The substantial literature produced by the combustion sciences, biomass energy, and paper processing research communities suggest that particle carbon comprises a wide array of light-absorbing compounds having distinct light-absorbing properties of varying degrees of extinction efficiency. These materials accumulate in the particle phase, and are emitted at all stages of solid fuel pyrolysis and combustion. Filter-based measurements of carbonaceous PM collected from various solid fuel combustion sources show substantial variability in solar wavelength-dependent light absorption, with Angstrom Exponents ranging from as high as 12, down to 1. In this presentation, the fuel and combustion variables determining the degree of light absorption by carbonaceous particle components will be discussed, followed by a presentation of the results of a study applying the adjoint of the GEOS-Chem chemical transport model to an estimation of the sensitivity of direct forcing by carbonaceous particles to variation in burning phase-specific AE values.

  3. Ultraviolet light curves of beta Lyrae: Comparison of OAO A-2, IUE, and Voyager Observations

    NASA Technical Reports Server (NTRS)

    Kondo, Yoji; Mccluskey, George E.; Silvis, Jeffery M. S.; Polidan, Ronald S.; Mccluskey, Carolina P. S.; Eaton, Joel A.

    1994-01-01

    The six-band ultraviolet light curves of beta Lyrae obtained with the Orbiting Astronomical Observatory (OAO) A-2 in 1970 exhibited a very unusual behavior. The secondary minimum deepened at shorter wavelength, indicating that one was not observing light variations caused primarily by the eclipses of two stars having a roughly Planckian energy distribution. It was then suggested that the light variations were caused by a viewing angle effect of an optically thick, ellipsoidal circumbinary gas cloud. Since 1978 beta Lyrae has been observed with the International Ultraviolet Explorer (IUE) satellite. We have constructed ultraviolet light curves from the IUE archival data for comparison with the OAO A-2 results. We find that they are in substantial agreement with each other. The Voyager ultraviolet spectrometer was also used to observe this binary during a period covered by IUE observations. The Voyager results agree with those of the two other satellite observatories at wavelengths longer than about 1350 A. However, in the wavelength region shorter than the Lyman-alpha line at 1216 A, the light curves at 1085 and 965 A show virtually no light variation except an apparent flaring near phase 0.7, which is also in evidence at longer wavelengths. We suggest that the optically thick circumbinary gas cloud, which envelops the two stars completely, assumes a roughly spherical shape when observed at these shorter wavelengths.

  4. Probing Coagulation Behavior of Individual Aluminum Species for Removing Corresponding Disinfection Byproduct Precursors: The Role of Specific Ultraviolet Absorbance

    PubMed Central

    Zhao, He; Hu, Chengzhi; Zhang, Di; Liu, Huijuan; Qu, Jiuhui

    2016-01-01

    Coagulation behavior of aluminum chloride and polyaluminum chloride (PACl) for removing corresponding disinfection byproduct (DBP) precursors was discussed in this paper. CHCl3, bromine trihalomethanes (THM-Br), dichloroacetic acid (DCAA) and trichloroacetic acid (TCAA) formation potential yields were correlated with specific ultraviolet absorbance (SUVA) values in different molecular weight (MW) fractions of humic substances (HS), respectively. Correlation analyses and principal component analysis were performed to examine the relationships between SUVA and different DBP precursors. To acquire more structural characters of DBP precursors and aluminum speciation, freeze-dried precipitates were analyzed by fourier transform infrared (FTIR) and C 1s, Al 2p X-ray photoelectron spectroscopy (XPS). The results indicated that TCAA precursors (no MW limits), DCAA and CHCl3 precursors in low MW fractions (MW<30 kDa) had a relatively good relations with SUVA values. These DBP precursors were coagulated more easily by in situ Al13 of AlCl3 at pH 5.0. Due to relatively low aromatic content and more aliphatic structures, THM-Br precursors (no MW limits) and CHCl3 precursors in high MW fractions (MW>30 kDa) were preferentially removed by PACl coagulation with preformed Al13 species at pH 5.0. Additionally, for DCAA precursors in high MW fractions (MW>30 kDa) with relatively low aromatic content and more carboxylic structures, the greatest removal occurred at pH 6.0 through PACl coagulation with aggregated Al13 species. PMID:26824243

  5. Probing Coagulation Behavior of Individual Aluminum Species for Removing Corresponding Disinfection Byproduct Precursors: The Role of Specific Ultraviolet Absorbance.

    PubMed

    Zhao, He; Hu, Chengzhi; Zhang, Di; Liu, Huijuan; Qu, Jiuhui

    2016-01-01

    Coagulation behavior of aluminum chloride and polyaluminum chloride (PACl) for removing corresponding disinfection byproduct (DBP) precursors was discussed in this paper. CHCl3, bromine trihalomethanes (THM-Br), dichloroacetic acid (DCAA) and trichloroacetic acid (TCAA) formation potential yields were correlated with specific ultraviolet absorbance (SUVA) values in different molecular weight (MW) fractions of humic substances (HS), respectively. Correlation analyses and principal component analysis were performed to examine the relationships between SUVA and different DBP precursors. To acquire more structural characters of DBP precursors and aluminum speciation, freeze-dried precipitates were analyzed by fourier transform infrared (FTIR) and C 1s, Al 2p X-ray photoelectron spectroscopy (XPS). The results indicated that TCAA precursors (no MW limits), DCAA and CHCl3 precursors in low MW fractions (MW<30 kDa) had a relatively good relations with SUVA values. These DBP precursors were coagulated more easily by in situ Al13 of AlCl3 at pH 5.0. Due to relatively low aromatic content and more aliphatic structures, THM-Br precursors (no MW limits) and CHCl3 precursors in high MW fractions (MW>30 kDa) were preferentially removed by PACl coagulation with preformed Al13 species at pH 5.0. Additionally, for DCAA precursors in high MW fractions (MW>30 kDa) with relatively low aromatic content and more carboxylic structures, the greatest removal occurred at pH 6.0 through PACl coagulation with aggregated Al13 species.

  6. Optimization of the size ratio of Sn sphere and laser focal spot for an extreme ultraviolet light source

    SciTech Connect

    Yuspeh, S.; Sequoia, K. L.; Tao, Y.; Tillack, M. S.; Burdt, R.; Najmabadi, F.

    2008-12-01

    The effect of the ratio of Sn sphere diameter to laser focal spot size (SD/FSS) on conversion efficiency (CE) from laser to in-band (2%) 13.5 nm extreme ultraviolet (EUV) light was investigated by fixing the laser spot size and irradiating variable diameter spheres. It was found that a minimum SD/FSS, i.e., 2.5, is necessary to produce high in-band CE, which is 15% higher than planar targets. Two-dimensional plasma density profile maps showed that the density of the dominant in-band EUV emission region and the size of the surrounding absorbing plasma can be manipulated by geometric effects of the SD/FSS ratio.

  7. The Ultraviolet Light Inactivation of ΦX174 Bacteriophage at Different wave Lengths and pH's

    PubMed Central

    Setlow, Richard; Boyce, Richard

    1960-01-01

    The bacterial virus, ΦX174, which contains a single strand of DNA has been inactivated by different wave lengths of monochromatic ultraviolet light at pH 7, 2, and 12. The action spectra for inactivation at these three pH's all showed minima at 2400 A rather than at 2300 A, which is the characteristic absorption minimum of DNA. The shapes of the action spectra have been analyzed in terms of the effects of absorbed light on the pyrimidines and purines rather than the effect on nucleoprotein. In this interpretation the pyrimidines are at least 2 to 3 times more sensitive than the purines. The quantum yield for inactivation of the virus at 2650 A and pH 7 is 0.006. The quantum efficiency for quanta absorbed in the pyrimidines is 0.0085 and for the purines 0.0035. It is pointed out that action spectra for single- and double-stranded polynucleotides should have minima at different wave lengths, and that this difference may be used to distinguish between these two configurations in vivo. PMID:13750383

  8. Exposure of bovine dermal tissue to ultraviolet light under the Antarctic ozone hole

    NASA Astrophysics Data System (ADS)

    Takahashi, Tetsuya; Ogura, Takayuki; Tanaka, Keisuke; Hattori, Shunji; Kudoh, Sakae; Imura, Satoshi

    2016-12-01

    Bovine dermis was exposed outdoors in the Antarctic in 2013 to study the skin damage caused by short-wavelength ultraviolet light under the ozone hole. Collagen was extracted from the exposed dermis with pepsin. The amount of solubilized collagen in the exposed dermis was only 20%-40% of that in dermis shielded from ultraviolet light. The dermis was most difficult to extract when exposed in summer, and then when exposed in spring. Differential scanning calorimetry was used to determine the melting endothermic behavior of the dermal tissue. The peak temperature was highest for the dermis exposed in summer. The exposed dermis was degraded with cyanogen bromide to determine whether cross-linking had occurred. Cross-linked peptides were detected in the dermis exposed in summer or spring, but the dermis exposed in autumn did not differ markedly from the light-shielded dermis. These data show that cross-linkages were readily formed in the collagen molecule chains in dermis exposed to ultraviolet light in summer, when solar elevation is highest and the period of sunshine is longest. A comparison of the dermis exposed in spring and that exposed in autumn showed that cross-linkages were formed more readily by ultraviolet light in spring, when the ozone hole occurred.

  9. Exploring Light’s Interactions with Bubbles and Light Absorbers in Photoelectrochemical Devices using Ray Tracing

    SciTech Connect

    Stevens, John Colby

    2012-12-01

    Ray tracing was used to perform optical optimization of arrays of photovoltaic microrods and explore the interaction between light and bubbles of oxygen gas on the surface of the microrods. The incident angle of light was varied over a wide range. The percent of incident light absorbed by the microrods and reflected by the bubbles was computed over this range. It was found that, for the 10 μm diameter, 100 μm tall SrTiO3 microrods simulated in the model, the optimal center-­to-­center spacing was 14 μm for a square grid. This geometry produced 75% average and 90% maximum absorbance. For a triangular grid using the same microrods, the optimal center-­to-­center spacing was 14 μm. This geometry produced 67% average and 85% maximum absorbance. For a randomly laid out grid of 5 μm diameter, 100 μm tall SrTiO3 microrods with an average center-­to-­center spacing of 20 μm, the average absorption was 23% and the maximum absorption was 43%. For a 50% areal coverage fraction of bubbles on the absorber surface, between 2%-­20% of the incident light energy was reflected away from the rods by the bubbles, depending upon incident angle and bubble morphology.

  10. The Feynman-Wheeler Perfect Absorber Theory in a New Light

    NASA Astrophysics Data System (ADS)

    Sidharth, B. G.

    2010-08-01

    The original Feynman-Wheeler perfect absorber theory lead to the Instantaneous Action at a Distance formulation. We observe that this is perfectly meaningful in the light of recent studies pointing to a small but non-zero photon mass. The Quantum Mechanical effects within the Compton scale of such a small mass photon would lead to the above formulation.

  11. A charge coupled device array detector for single-wavelength and multiwavelength ultraviolet absorbance in capillary electrophoresis.

    PubMed

    Bergström, E T; Goodall, D M; Pokrić, B; Allinson, N M

    1999-10-01

    A fundamental limitation to the use of single-point absorbance detection for capillary electrophoresis is irradiance, since it is not possible to create an image at the detection point on capillary that is brighter than the light source. This limitation may be overcome by illuminating a length of the capillary using a fiber-optic bundle and using a charge coupled device (CCD) camera that can image the full length of the illuminated zone. The present paper describes design and development of a CCD detector for UV absorbance that can be used in both multiwavelength and single-wavelength modes. The CCD camera images analyte peaks in the capillary dimension, together with wavelength-resolved absorbance in the dimension perpendicular to the capillary. Successive snapshots of the peaks are added together, after appropriate correction for time-dependent peak displacement, without sacrificing spatial resolution. Measured baseline rms noise values at 200 nm are 34 μAU using a holographic grating in multiwavelength mode and 8 μAU with the addition of a band-pass filter. Both values are in excellent agreement with calculations of limiting shot noise. Performance in multiwavelength mode is constrained by the 470-ms readout time of the CCD used, which sets a maximum duty cycle of 2.3%. Noise contributions from source intensity fluctuations are reduced by using a portion of the CCD image to provide a baseline reference signal. With 4-hydroxybenzoate as test analyte, the linear dynamic range in multiwavelength mode is shown to be between 3 and 4 orders of magnitude. High-quality spectra of 2-, 3-, and 4-methylbenzoates are obtained on capillary and used in deconvolution of closely migrating peaks of the 2- and 3-isomers.

  12. 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.

  13. 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...

  14. Ultraviolet Light Generation and Transport in the Final Optics Assembly of the National Ignition Facility

    SciTech Connect

    Wegner, P.; Hackel, L.; Feit, M.; Parham, T.; Kozlowski, M.; Whitman, P.

    2015-02-12

    The design of the National Ignition Facility (NIF) includes a Final Optics Assembly (FOA) subsystem for ultraviolet (UV) light generation and transport for each of the 192 beamlines. Analytical and experimental work has been done to help understand and predict the performance of FOA.

  15. Extending the use of ultraviolet light for fruit quality sorting in citrus packinghouses

    Technology Transfer Automated Retrieval System (TEKTRAN)

    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 ...

  16. Ultraviolet-B light treatment increases antioxidant capacity of carrot products

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Abiotic stresses such as cutting and ultraviolet (UV) light exposure of plant cells triggers an increased activity response by phenylalanine ammonia-lyase (PAL) and chalcone synthase resulting in increased synthesis of phenolic compounds, mainly anthocyanins and flavonoids. This study investigated ...

  17. Pulsed ultraviolet light reduces immunoglobulin E binding to atlantic white shrimp (litopenaeus setiferus).

    Technology Transfer Automated Retrieval System (TEKTRAN)

    To date, the only effective method to prevent allergic reactions to shellfish is complete avoidance; however, if processing methods could be employed to minimize shellfish allergens before products reach consumers, illness could be substantially lessened. Pulsed ultraviolet light (PUV), a novel food...

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

    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...

  19. Electrically tunable selective reflection of light from ultraviolet to visible and infrared by heliconical cholesterics.

    PubMed

    Xiang, Jie; Li, Yannian; Li, Quan; Paterson, Daniel A; Storey, John M D; Imrie, Corrie T; Lavrentovich, Oleg D

    2015-05-20

    Electrical tuning of selective reflection of light is achieved in a very broad spectral range from ultraviolet to visible and infrared by an oblique helicoidal state of a cholesteric liquid crystal in a wide temperature range (including room temperature). The phenomenon offers potential applications in tunable smart windows, lasers, optical filters and limiters, as well as in displays.

  20. Use of pulsed ultraviolet light to reduce the allergenic potency of soybean extracts.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Pulsed ultraviolet light (PUV), a non-thermal food processing technology, is reported to be able to inactivate enzymes and reduce allergen levels from peanut extracts. The objective of this study was to determine if PUV would reduce the allergen levels and allergenic potency of soy extracts. Soy ext...

  1. Application of ultraviolet-C light on oranges for the inactivation of postharvest wound pathogens

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Germicidal effects of ultraviolet-C (UV-C) light on the postharvest wound pathogens of citrus fruits namely Penicillium digitatum and Penicillium italicum were investigated. P. digitatum and P. italicum spores were inoculated (4.00 – 4.50 log cfu/ orange) onto Washington navel oranges (Citrus sinens...

  2. Applications of ultraviolet light in the preparation of platelet concentrates

    SciTech Connect

    Pamphilon, D.H.; Corbin, S.A.; Saunders, J.; Tandy, N.P.

    1989-06-01

    Passenger lymphocytes in platelet concentrates (PCs) may induce the formation of lymphocytotoxic antibodies (LCTAbs) and subsequent refractoriness to platelet transfusions. Ultraviolet (UV) irradiation can prevent lymphocytes' acting as stimulator or responder cells in mixed-lymphocyte reactions (MLRs) and could theoretically prevent LCTAb formation in vivo. A system has been devised for the delivery of UV irradiation to PCs; platelet storage characteristics and MLRs were evaluated in UV-irradiated PCs harvested from healthy donors with the Haemonetics V50 and PCS cell separators. MLR and response to phytohemagglutinin stimulation were abolished by a dose of 3000 joules per m2 at a mean wavelength of 310 nm. Platelet aggregatory responses to adenosine diphosphate (ADP), ristocetin, collagen and epinephrine, hypotonic shock response, and pH showed no important differences when control PCs and PCs irradiated as above were compared during 5 days of storage in Fenwal PL-1240 packs. Lactate production during storage was significantly higher in UV-treated PCs (p less than 0.001), but values did not exceed 20 mmol per L. UV transmission at 310 nm in standard blood product containers, including the Fenwal PL-146, PL-1240, and PL-732, was low (less than 30%), but it was acceptable in the Delmed Cryostorage and DuPont SteriCell packs (greater than 50%). UV irradiation may provide a simple and inexpensive means of producing nonimmunogenic PCs.

  3. Specific ultra-violet absorbance as an indicator measurement of merucry sources in an Adirondack River basin

    USGS Publications Warehouse

    Burns, Douglas A.; Aiken, George R.; Bradley, Paul M.; Journey, Celeste; Schelker, Jakob

    2013-01-01

    The Adirondack region of New York has been identified as a hot spot where high methylmercury concentrations are found in surface waters and biota, yet mercury (Hg) concentrations vary widely in this region. We collected stream and groundwater samples for Hg and organic carbon analyses across the upper Hudson River, a 493 km2 basin in the central Adirondacks to evaluate and model the sources of variation in filtered total Hg (FTHg) concentrations. Variability in FTHg concentrations during the growing seasons (May-Oct) of 2007-2009 in Fishing Brook, a 66-km2 sub-basin, was better explained by specific ultra-violet absorbance at 254 nm (SUVA254), a measure of organic carbon aromaticity, than by dissolved organic carbon (DOC) concentrations, a commonly used Hg indicator. SUVA254 was a stronger predictor of FTHg concentrations during the growing season than during the dormant season. Multiple linear regression models that included SUVA254 values and DOC concentrations could explain 75 % of the variation in FTHg concentrations on an annual basis and 84 % during the growing season. A multiple linear regression landscape modeling approach applied to 27 synoptic sites across the upper Hudson basin found that higher SUVA254 values are associated with gentler slopes, and greater riparian area, and lower SUVA254 values are associated with an increasing influence of open water. We hypothesize that the strong Hg?SUVA254 relation in this basin reflects distinct patterns of FTHg and SUVA254 that are characteristic of source areas that control the mobilization of Hg to surface waters, and that the seasonal influence of these source areas varies in this heterogeneous basin landscape.

  4. Effects of morphology on the radiative properties of internally mixed light absorbing carbon aerosols with different aging status.

    PubMed

    Cheng, Tianhai; Wu, Yu; Chen, Hao

    2014-06-30

    Light absorbing carbon aerosols play a substantial role in climate change through radiative forcing, which is the dominant absorber of solar radiation. Radiative properties of light absorbing carbon aerosols are strongly dependent on the morphological factors and the mixing mechanism of black carbon with other aerosol components. This study focuses on the morphological effects on the optical properties of internally mixed light absorbing carbon aerosols using the numerically exact superposition T-matrix method. Three types aerosols with different aging status such as freshly emitted BC particles, thinly coated light absorbing carbon aerosols, heavily coated light absorbing carbon aerosols are studied. Our study showed that morphological factors change with the aging of internally mixed light absorbing carbon aerosols to result in a dramatic change in their optical properties. The absorption properties of light absorbing carbon aerosols can be enhanced approximately a factor of 2 at 0.67 um, and these enhancements depend on the morphological factors. A larger shell/core diameter ratio of volume-equivalent shell-core spheres (S/C), which indicates the degree of coating, leads to stronger absorption. The enhancement of absorption properties accompanies a greater enhancement of scattering properties, which is reflected in an increase in single scattering albedo (SSA). The enhancement of single scattering albedo due to the morphological effects can reach a factor of 3.75 at 0.67 μm. The asymmetry parameter has a similar yet smaller enhancement. Moreover, the corresponding optical properties of shell-and-core model determined by using Lorenz -Mie solutions are presented for comparison. We found that the optical properties of internally mixed light absorbing carbon aerosol can differ fundamentally from those calculated for the Mie theory shell-and-core model, particularly for thinly coated light absorbing carbon aerosols. Our studies indicate that the complex morphology

  5. Proliferative and toxic effects of ultraviolet light and inflammation on epidermal pigment cells

    SciTech Connect

    Nordlund, J.J.; Ackles, A.E.; Traynor, F.F.

    1981-10-01

    The ear of the mouse is useful for studying the effects of ultraviolet light on epidermal pigment cells. The quantity of light penetrating into the skin causing an inflammatory response can be assessed easily by measuring with an engineering calipers the swelling of the ear. The inflammatory response of the ear exhibits a linear relationship to the dose of light delivered. We observed that doses of shortwave ultraviolet light which are noninflammatory when repeated at daily intervals induce moderate to severe inflammation. Small doses of psoralen and prolonged exposure to UVA (PUVA) were more inflammatory than larger amounts of psoralen and short exposure to light. Doses of shortwave ultraviolet light and PUVA which produce only a minimal inflammation of the skin stimulate the proliferation of epidermal melanocytes. In contrast, PUVA in doses sufficiently large to cause a marked inflammatory reaction in the skin seems injurious to pigment cells and kills them or causes only a minimal proliferative response. The inflammatory reaction itself does not seem to stimulate or inhibit the proliferation of melanocytes. Prostaglandins A, E, and F2 alpha have no effect on the proliferation of epidermal pigment cells. In contrast, dimethyl sulfoxide (DMSO) and allergic contact dermatitis increase the numerical density of pigment cells. Steroids may block the function of the enzyme tyrosinase. Our experiments indicate that pigment cells, like many other varieties of cells, are susceptible to injury and can be killed at least by large doses of PUVA.

  6. Photon extraction from nitride ultraviolet light-emitting devices

    DOEpatents

    Schowalter, Leo J; Chen, Jianfeng; Grandusky, James R

    2015-02-24

    In various embodiments, a rigid lens is attached to a light-emitting semiconductor die via a layer of encapsulant having a thickness insufficient to prevent propagation of thermal expansion mismatch-induced strain between the rigid lens and the semiconductor die.

  7. Ultraviolet absorbing copolymers

    DOEpatents

    Gupta, Amitava; Yavrouian, Andre H.

    1982-01-01

    Photostable and weather stable absorping copolymers have been prepared from acrylic esters such as methyl methacrylate containing 0.1 to 5% of an 2-hydroxy-allyl benzophenone, preferably the 4,4' dimethoxy derivative thereof. The pendant benzophenone chromophores protect the acrylic backbone and when photoexcited do not degrade the ester side chain, nor abstract hydrogen from the backbone.

  8. EDITORIAL: Extreme Ultraviolet Light Sources for Semiconductor Manufacturing

    NASA Astrophysics Data System (ADS)

    Attwood, David

    2004-12-01

    The International Technology Roadmap for Semiconductors (ITRS) [1] provides industry expectations for high volume computer chip fabrication a decade into the future. It provides expectations to anticipated performance and requisite specifications. While the roadmap provides a collective projection of what international industry expects to produce, it does not specify the technology that will be employed. Indeed, there are generally several competing technologies for each two or three year step forward—known as `nodes'. Recent successful technologies have been based on KrF (248 nm), and now ArF (193 nm) lasers, combined with ultraviolet transmissive refractive optics, in what are known as step and scan exposure tools. Less fortunate technologies in the recent past have included soft x-ray proximity printing and, it appears, 157 nm wavelength F2 lasers. In combination with higher numerical aperture liquid emersion optics, 193 nm is expected to be used for the manufacture of leading edge chip performance for the coming five years. Beyond that, starting in about 2009, the technology to be employed is less clear. The leading candidate for the 2009 node is extreme ultraviolet (EUV) lithography, however this requires that several remaining challenges, including sufficient EUV source power, be overcome in a timely manner. This technology is based on multilayer coated reflective optics [2] and an EUV emitting plasma. Following Moore's Law [3] it is expected, for example, that at the 2009 `32 nm node' (printable patterns of 32 nm half-pitch), isolated lines with 18 nm width will be formed in resist (using threshold effects), and that these will be further narrowed to 13 nm in transfer to metalized electronic gates. These narrow features are expected to provide computer chips of 19 GHz clock frequency, with of the order of 1.5 billion transistors per chip [1]. This issue of Journal of Physics D: Applied Physics contains a cluster of eight papers addressing the critical

  9. Investigating the protective properties of milk phospholipids against ultraviolet light exposure in a skin equivalent model

    NASA Astrophysics Data System (ADS)

    Russell, Ashley; Laubscher, Andrea; Jimenez-Flores, Rafael; Laiho, Lily H.

    2010-02-01

    Current research on bioactive molecules in milk has documented health advantages of bovine milk and its components. Milk Phospholipids, selected for this study, represent molecules with great potential benefit in human health and nutrition. In this study we used confocal reflectance and multiphoton microscopy to monitor changes in skin morphology upon skin exposure to ultraviolet light and evaluate the potential of milk phospholipids in preventing photodamage to skin equivalent models. The results suggest that milk phospholipids act upon skin cells in a protective manner against the effect of ultraviolet (UV) radiation. Similar results were obtained from MTT tissue viability assay and histology.

  10. The Investigation of Property of Radiation and Absorbed of Infrared Lights of the Biological Tissues

    NASA Astrophysics Data System (ADS)

    Pang, Xiao-Feng; Deng, Bo; Xiao, He-Lan; Cai, Guo-Ping

    2010-04-01

    The properties of absorption of infrared light for collagen, hemoglobin, bivine serum albumen (BSA) protein molecules with α- helix structure and water in the living systems as well as the infrared transmission spectra for person’s skins and finger hands of human body in the region of 400-4000 cm-1 (i.e., wavelengths of 2-20 μm) have been collected and determined by using a Nicolet Nexus 670 FT-IR Spectrometer, a Perkin Elmer GX FT-IR spectrometer, an OMA (optical multichannel analysis) and an infrared probe systems, respectively. The experimental results obtained show that the protein molecules and water can all absorb the infrared lights in the ranges of 600-1900 cm-1 and 2900-3900 cm-l, but their properties of absorption are somewhat different due to distinctions of their structure and conformation and molecular weight. We know from the transmission spectra of person’s finger hands and skin that the infrared lights with wavelengths of 2 μm-7 μm can not only transmit over the person’s skin and finger hands, but also be absorbed by the above proteins and water in the living systems. Thus, we can conclude from this study that the human beings and animals can absorb the infrared lights with wavelengths of 2 μm-7 μm.

  11. Measurements of light absorbing particulates on the glaciers in the Cordillera Blanca, Peru

    NASA Astrophysics Data System (ADS)

    Schmitt, C. G.; All, J. D.; Schwarz, J. P.; Arnott, W. P.; Cole, R. J.; Lapham, E.; Celestian, A.

    2014-10-01

    Glaciers in the tropical Andes have been rapidly losing mass since the 1970s. In addition to the documented increase in air temperature, increases in light absorbing particulates deposited on glaciers could be contributing to the observed glacier loss. Here we report on measurements of light absorbing particulates sampled from glaciers during three surveys in the Cordillera Blanca in Peru. During three research expeditions in the dry seasons (May-August) of 2011, 2012 and 2013, two hundred and forty snow samples were collected from fifteen mountain peaks over altitudes ranging from 4800 to nearly 6800 m. Several mountains were sampled each of the three expeditions and some mountains were sampled multiple times during the same expedition. Collected snow samples were melted and filtered in the field then later analyzed using the Light Absorption Heating Method (LAHM), a new technique that measures the ability of particulates on filters to absorb visible light. LAHM results have been calibrated using filters with known amounts of fullerene soot, a common industrial surrogate for black carbon (BC). As sample filters often contain dust in addition to BC, results are presented in terms of effective Black Carbon (eBC). During the 2013 survey, snow samples were collected and kept frozen for analysis with a Single Particle Soot Photometer (SP2). Calculated eBC mass from the filter analysis and the SP2 refractory Black Carbon (rBC) results were well correlated (r2 = 0.92). These results indicate that a substantial portion of the light absorbing particulates in the more polluted areas were likely BC. The three years of data show that glaciers in the Cordillera Blanca Mountains close to human population centers have substantially higher levels of eBC (as high as 70 ng g-1) than remote glaciers (as low as 2.0 ng g-1 eBC), indicating that population centers can influence local glaciers by sourcing BC.

  12. Measurements of light-absorbing particles on the glaciers in the Cordillera Blanca, Peru

    NASA Astrophysics Data System (ADS)

    Schmitt, C. G.; All, J. D.; Schwarz, J. P.; Arnott, W. P.; Cole, R. J.; Lapham, E.; Celestian, A.

    2015-02-01

    Glaciers in the tropical Andes have been rapidly losing mass since the 1970s. In addition to the documented increase in temperature, increases in light-absorbing particles deposited on glaciers could be contributing to the observed glacier loss. Here we report on measurements of light-absorbing particles sampled from glaciers during three surveys in the Cordillera Blanca Mountains in Peru. During three research expeditions in the dry seasons (May-August) of 2011, 2012 and 2013, 240 snow samples were collected from 15 mountain peaks over altitudes ranging from 4800 to nearly 6800 m. Several mountains were sampled each of the 3 years and some mountains were sampled multiple times during the same year. Collected snow samples were melted and filtered in the field then later analyzed using the Light Absorption Heating Method (LAHM), a new technique that measures the ability of particles on filters to absorb visible light. LAHM results have been calibrated using filters with known amounts of fullerene soot, a common industrial surrogate for black carbon (BC). As sample filters often contain dust in addition to BC, results are presented in terms of effective black carbon (eBC). During the 2013 survey, snow samples were collected and kept frozen for analysis with a Single Particle Soot Photometer (SP2). Calculated eBC mass from the LAHM analysis and the SP2 refractory black carbon (rBC) results were well correlated (r2 = 0.92). These results indicate that a substantial portion of the light-absorbing particles in the more polluted regions were likely BC. The 3 years of data show that glaciers in the Cordillera Blanca Mountains close to human population centers have substantially higher levels of eBC (as high as 70 ng g-1) than remote glaciers (as low as 2.0 ng g-1 eBC), indicating that population centers can influence local glaciers by sourcing BC.

  13. Ultraviolet Light Emitting Diode Use in Advanced Oxidation Processes

    DTIC Science & Technology

    2014-03-27

    assume both the power requirements and lifetimes of UV LEDs will improve rapidly in the coming decades. LEDs turn electrical energy into light energy ... energy consumption or limiting the time the LED is powered , but do not require the highest possible rate of contamination destruction. 20 This might...as they are durable; compact; can be powered by low voltage, direct current from solar cells or batteries; and do not contain other hazardous

  14. Stratocumulus to Cumulus Transition Capped by a Light-Absorbing Smoke Layer

    NASA Astrophysics Data System (ADS)

    Yamaguchi, T.; Feingold, G.; Kazil, J.; McComiskey, A. C.

    2015-12-01

    Biomass burning aerosol emitted from Africa seasonally advects over the eastern Atlantic and forms a layer of light-absorbing smoke above stratocumulus clouds, which influences heating profiles, dynamics, and cloud microphysics. In this study, large-eddy simulation is used to investigate the effect of the absorbing smoke layer on the stratocumulus to cumulus transition (SCT). A prognostic absorbing smoke model incorporates humidity effects on optical properties, and is coupled with a two-moment bulk microphysics scheme and an interactive radiation code. Smoke both absorbs shortwave radiation and acts as cloud condensation nuclei (CCN). Simulations are of three day duration. The simulations assess sensitivity of the SCT to distance of the smoke layer from the cloud top, aerosol optical thickness and single scattering albedo, and precipitation. Our simulations show that 1) As a shortwave absorber, the smoke stabilizes the free atmosphere and strengthens the temperature jump at the boundary layer top, which limits entrainment; 2) Smoke helps evaporate cloud during daytime, which amplifies the diurnal cycle of cloud cover; 3) As a source of CCN, the entrained smoke suppresses rain formation, which inhibits precipitation-generated cloud breakup. The net effect of smoke is modification of heating profiles to limit the deepening of the planetary boundary layer, and suppression of precipitation. This leads to enhancement of the diurnal cycle of cloudiness but a delay in the SCT.

  15. Dependence of photoinduced bending behavior of diarylethene crystals on irradiation wavelength of ultraviolet light.

    PubMed

    Kitagawa, Daichi; Tanaka, Rika; Kobatake, Seiya

    2015-11-07

    The dependence of the photoinduced bending behavior of diarylethene crystals on the ultraviolet light irradiation wavelength was investigated. When irradiated with 365 nm light, a crystal of 1,2-bis(5-methyl-2-phenyl-4-thiazolyl)perfluorocyclopentene (1a) bends toward the incident light. On the other hand, when irradiated with 380 nm light, the crystal of 1a first bends away from the light source and then bends toward the incident light. To explain this bending behavior, we propose a comprehensive mechanism based on the depth of the photochromic reaction from the crystal surface. This mechanism is successfully supported by the change of cell parameters associated with the photochromic reaction upon irradiation with 380 nm light, which was determined by in situ X-ray crystallographic analysis.

  16. Enhancing the light extraction efficiency of AlGaN deep ultraviolet light emitting diodes by using nanowire structures

    SciTech Connect

    Djavid, Mehrdad; Mi, Zetian

    2016-02-01

    The performance of conventional AlGaN deep ultraviolet light emitting diodes has been limited by the extremely low light extraction efficiency (<10%), due to the unique transverse magnetic (TM) polarized light emission. Here, we show that, by exploiting the lateral side emission, the extraction efficiency of TM polarized light can be significantly enhanced in AlGaN nanowire structures. Using the three-dimensional finite-difference time domain simulation, we demonstrate that the nanowire structures can be designed to inhibit the emission of guided modes and redirect trapped light into radiated modes. A light extraction efficiency of more than 70% can, in principle, be achieved by carefully optimizing the nanowire size, nanowire spacing, and p-GaN thickness.

  17. STUDENT AWARD FINALIST: Study of Self-Absorbed Vacuum Ultraviolet Radiation during Pulsed Atmospheric Breakdown in Air

    NASA Astrophysics Data System (ADS)

    Laity, George; Fierro, Andrew; Hatfield, Lynn; Neuber, Andreas

    2011-10-01

    This paper describes recent experiments to investigate the role of self-produced vacuum ultraviolet (VUV) radiation in the physics of pulsed atmospheric breakdown. A unique apparatus was constructed which enables the detailed exploration of VUV light in the range 115-135 nm, which is emitted from breakdown between two point-point electrodes in an air environment at atmospheric pressure. Time-resolved diagnostics include VUV sensitive photomultipliers, intensified CCD imaging, optically isolated high voltage probes, and fast rise-time Rogowski current monitors. Temporally resolved spectroscopy from air breakdowns revealed VUV emission is released during the initial streamer phase before voltage collapse, with the majority of the emission lines identified from various atmospheric gases or surface impurities. Imaging of VUV radiation was performed which conserved the spatial emission profile, and distinct differences between nitrogen and oxygen VUV emission during onset of breakdown have been observed. Specifically, the self-absorption of HI, OI, and NI lines is addressed which elucidates the role of radiation transport during the photon-dominated streamer breakdown process. Supported by AFOSR, NASA / TSGC, DEPS, and IEEE DEIS.

  18. Blue Light and Ultraviolet Radiation Exposure from Infant Phototherapy Equipment.

    PubMed

    Pinto, Iole; Bogi, Andrea; Picciolo, Francesco; Stacchini, Nicola; Buonocore, Giuseppe; Bellieni, Carlo V

    2015-01-01

    Phototherapy is the use of light for reducing the concentration of bilirubin in the body of infants. Although it has become a mainstay since its introduction in 1958, a better understanding of the efficacy and safety of phototherapy applications seems to be necessary for improved clinical practices and outcomes. This study was initiated to evaluate workers' exposure to Optical Radiation from different types of phototherapy devices in clinical use in Italy. During infant phototherapy the staff monitors babies periodically for around 10 min every hour, and fixation of the phototherapy beam light frequently occurs: almost all operators work within 30 cm of the phototherapy source during monitoring procedures, with most of them commonly working at ≤25 cm from the direct or reflected radiation beam. The results of this study suggest that there is a great variability in the spectral emission of equipments investigated, depending on the types of lamps used and some phototherapy equipment exposes operators to blue light photochemical retinal hazard. Some of the equipment investigated presents relevant spectral emission also in the UVA region. Taking into account that the exposure to UV in childhood has been established as an important contributing factor for melanoma risk in adults and considering the high susceptibility to UV-induced skin damage of the newborn, related to his pigmentary traits, the UV exposure of the infant during phototherapy should be "as low as reasonably achievable," considering that it is unnecessary to the therapy. It is recommended that special safety training be provided for the affected employees: in particular, protective eyewear can be necessary during newborn assistance activities carried out in proximity of some sources. The engineering design of phototherapy equipment can be optimized. Specific requirements for photobiological safety of lamps used in the phototherapy equipment should be defined in the safety product standard for such

  19. Light trapping in ZnO nanowire arrays covered with an absorbing shell for solar cells.

    PubMed

    Michallon, Jérôme; Bucci, Davide; Morand, Alain; Zanuccoli, Mauro; Consonni, Vincent; Kaminski-Cachopo, Anne

    2014-06-30

    The absorption properties of ZnO nanowire arrays covered with a semiconducting absorbing shell for extremely thin absorber solar cells are theoretically investigated by optical computations of the ideal short-circuit current density with three-dimensional rigorous coupled wave analysis. The effects of nanowire geometrical dimensions on the light trapping and absorption properties are reported through a comprehensive optical mode analysis. It is shown that the high absorptance of these heterostructures is driven by two different regimes originating from the combination of individual nanowire effects and nanowire arrangement effects. In the short wavelength regime, the absorptance is likely dominated by optical modes efficiently coupled with the incident light and interacting with the nearby nanowires (i.e. diffraction), induced by the period of core shell ZnO nanowire arrays. In contrast, in the long wavelength regime, the absorptance is governed by key optically guided modes, related to the diameter of individual core shell ZnO nanowires.

  20. Photoacoustic eigen-spectrum from light-absorbing microspheres and its application in noncontact elasticity evaluation

    NASA Astrophysics Data System (ADS)

    Gao, Xiaoxiang; Tao, Chao; Liu, Xiaojun; Wang, Xueding

    2017-01-01

    Noncontact evaluation of elastic properties of a microstructure is still a challenge in turbid media. In this Letter, we present the observation of a phenomenon—the photoacoustic eigen-spectrum from light-absorbing objects. Analysis and experiments demonstrate that the eigen-vibration information of a microstructure is imprinted in its photoacoustic coda waves after it is exposed to a laser pulse illumination. The spectral lines in the time-frequency map of photoacoustic coda waves correspond to the eigen-frequencies of the light-absorber. This phenomenon provides a physical basis for noncontact evaluation of elastic properties of a microstructure in turbid media. Elastic parameters can be accurately inversed from the measured photoacoustic eigen-spectrum.

  1. Light-induced pyroelectric effect as an effective approach for ultrafast ultraviolet nanosensing

    PubMed Central

    Wang, Zhaona; Yu, Ruomeng; Pan, Caofeng; Li, Zhaoling; Yang, Jin; Yi, Fang; Wang, Zhong Lin

    2015-01-01

    Zinc oxide is potentially a useful material for ultraviolet detectors; however, a relatively long response time hinders practical implementation. Here by designing and fabricating a self-powered ZnO/perovskite-heterostructured ultraviolet photodetector, the pyroelectric effect, induced in wurtzite ZnO nanowires on ultraviolet illumination, has been utilized as an effective approach for high-performance photon sensing. The response time is improved from 5.4 s to 53 μs at the rising edge, and 8.9 s to 63 μs at the falling edge, with an enhancement of five orders in magnitudes. The specific detectivity and the responsivity are both enhanced by 322%. This work provides a novel design to achieve ultrafast ultraviolet sensing at room temperature via light-self-induced pyroelectric effect. The newly designed ultrafast self-powered ultraviolet nanosensors may find promising applications in ultrafast optics, nonlinear optics, optothermal detections, computational memories and biocompatible optoelectronic probes. PMID:26403916

  2. Mid-ultraviolet light-emitting diode detects dipicolinic acid.

    SciTech Connect

    Bogart, Katherine Huderle Andersen; Lee, Stephen Roger; Temkin, Henryk; Crawford, Mary Hagerott; Dasgupta, Purnendu K.; Li, Qingyang; Allerman, Andrew Alan; Fischer, Arthur Joseph

    2005-06-01

    Dipicolinic acid (DPA, 2,6-pyridinedicarboxylic acid) is a substance uniquely present in bacterial spores such as that from anthrax (B. anthracis). It is known that DPA can be detected by the long-lived fluorescence of its terbium chelate; the best limit of detection (LOD) reported thus far using a large benchtop gated fluorescence instrument using a pulsed Xe lamp is 2 nM. We use a novel AlGaN light-emitting diode (LED) fabricated on a sapphire substrate that has peak emission at 291 nm. Although the overlap of the emission band of this LED with the absorption band of Tb-DPA ({lambda}{sub max} doublet: 273, 279 nm) is not ideal, we demonstrate that a compact detector based on this LED and an off-the-shelf gated photodetection module can provide an LOD of 0.4 nM, thus providing a basis for convenient early warning detectors.

  3. Photodegradation of aniline by goethite doped with boron under ultraviolet and visible light irradiation

    SciTech Connect

    Liu, Guanglong; Liao, Shuijiao; Zhu, Duanwei; Liu, Linghua; Cheng, Dongsheng; Zhou, Huaidong

    2011-08-15

    Highlights: {yields} Goethite modified by boron was prepared by sol-gel method in presence of boron acid at the low temperature. {yields} B-goethite has slight red shift in the band gap transition beside their stronger light absorption compared with pristine goethite. {yields} The results showed that semiconductor photocatalytic reaction mechanism should exist in the process of aniline degradation with goethite and B-goethite as photocatalyst. -- Abstract: In the present study, goethite and goethite doped with boron (B-goethite) were employed to detect the presence or absence of semiconductor photocatalytic reaction mechanism in the reaction systems. B-goethite was prepared by sol-gel method in presence of boron acid in order to improve its photocatalystic efficiency under the ultraviolet and visible light irradiation. The optical properties of goethite and B-goethite were characterized by ultraviolet and visible absorption spectra and the result indicated that B-goethite has slight red shift in the band gap transition beside their stronger light absorption compared with pristine goethite. Degradation of aniline was investigated in presence of goethite and B-goethite in aqueous solution. It was found that the B-goethite photocatalyst exhibited enhanced ultraviolet and visible light photocatalytic activity in degradation of aniline compared with the pristine goethite. The photocatalytic degradation mechanism of B-goethite was discussed.

  4. Effect of ultraviolet light on water- and fat-soluble vitamins in cow and goat milk.

    PubMed

    Guneser, O; Karagul Yuceer, Y

    2012-11-01

    The objective of this study was to investigate and compare the effects of UV light and heat treatment on vitamins A, B(2), C, and E in cow and goat milk. Vitamins were analyzed by reverse-phase high-pressure liquid chromatography. Ultraviolet and pasteurization treatments caused loss in vitamin C in milk. Pasteurization did not have any significant effect on vitamin B(2). However, UV light treatment decreased the amount of vitamin B(2) after several passes of milk through the UV system. In addition, UV light treatment decreased the amount of vitamins A and E. Vitamins C and E are more sensitive to UV light. UV light sensitivities of vitamins were C>E>A>B(2). These results show that UV light treatment decreases the vitamin content in milk. Also, the number of passes through the UV system and the initial amount of vitamins in milk are important factors affecting vitamin levels.

  5. Light-absorbent liquid immersion angled exposure for patterning 3D samples with vertical sidewalls

    NASA Astrophysics Data System (ADS)

    Kumagai, Shinya; Kubo, Hironori; Sasaki, Minoru

    2017-02-01

    To make photolithography patterns on 3D samples, the angled (inclined) exposure technique has been used so far. However, technological issues have emerged in making photolithography patterns on the surface of trench structures. The surface of the trench structures can be covered with a photoresist film by spray-coating but the photoresist film deposited on the sidewalls and bottom of the trench is generally thin. The thin photoresist film deposited inside the trench has been easily overdosed. Moreover, irregular patterns have frequently been formed by the light reflected inside the trench. In this study, we have developed liquid immersion photolithography using a light-absorbent material. The light-reflection inside the trench was suppressed. Various patterns were transferred in the photoresist film deposited on the trench structures which had an aspect ratio of 0.74. Compared to immersion photolithography using pure water under p-polarization light control, the light-absorbent liquid immersion photolithography developed here patterned well the surfaces of the trench sidewalls and bottom.

  6. Light, literacy and the absence of ultraviolet radiation in the development of myopia.

    PubMed

    Prepas, Stephen B

    2008-01-01

    As the prevalence of myopia steadily increases, reaching as high as 90% in some populations, investigators continue to look for causative factors other than family history. Most current research suggests an association of axial myopia with reading or either the presence or absence of light. Even though these studies are frequently inconsistent, non-reproducible or contradictory, many clinicians utilize them in recommending treatments for children, such as bifocals or atropine. By reviewing the biologic effects of non-ionizing electromagnetic fields, we may gain insight into these discrepancies as well as unify the combined role of literacy and light in the pathogenesis of myopia. These biologic effects are wavelength specific. The wavelength of artificial (either incandescent or fluorescent) light is primarily 700-400 nm, while the wavelength of natural light is 700-200 nm, inclusive of the ultraviolet spectrum. So the opposite findings of myopia resulting from either accommodation under continuous light or under darkness (form deprivation) can be reconciled by restating it: Close focusing in the absence of UV light may provoke axial myopia. Experimental evidence exhibiting both scleral remodeling under accommodation as well as the inhibition of scleral remodeling by the hardening of collagen under ultraviolet exposure may support this concept. Perhaps new research can look into the role of the presence or absence of UV light in animal models of myopia.

  7. Energy, Electron Transfer and Photocatalytic Reactions of Visible Light Absorbing Transition Metal Complexes

    SciTech Connect

    Schmehl, Russell H.

    2016-03-02

    This is the final technical report for a project carried out at Tulane University of New Orleans that describes the development of light induced (solar) reactions geared toward decomposing water into its component elements : hydrogen and oxygen. Much of the work involved optimizing systems for absorbing visible light and undergoing light promoted reactions to generate very strong reducing agents that are capable of reacting with water to produce hydrogen. Additional portions of the research were collaborative efforts to put the strong reducing agents to work in reaction with hydrogen generation catalysts prepared elsewhere. Time resolved laser spectroscopic methods were used to evaluate the light induced reactions and characterize very reactive intermediate substances formed during the reactions.

  8. Robust sensor for turbidity measurement from light scattering and absorbing liquids.

    PubMed

    Kontturi, Ville; Turunen, Petri; Uozumi, Jun; Peiponen, Kai-Erik

    2009-12-01

    Internationally standardized turbidity measurements for probing solid particles in liquid are problematic in the case of simultaneous light scattering and absorption. A method and a sensor to determine the turbidity in the presence of light absorption are presented. The developed sensor makes use of the total internal reflection of a laser beam at the liquid-prism interface, and the turbidity is assessed using the concept of laser speckle pattern. Using average filtering in speckle data analyzing the observed dynamic speckle pattern, which is due to light scattering from particles and the static speckle due to stray light of the sensor, can be separated from each other. Good correlation between the standard deviation of dynamic speckle and turbidity value for nonabsorbing and for absorbing liquids was observed. The sensor is suggested, for instance, for the measurement of ill-behaved as well as small-volume turbid liquids in both medicine and process industry.

  9. The Interior Analysis and 3-D Reconstruction of Internally-Mixed Light-Absorbing Atmospheric Particles

    NASA Astrophysics Data System (ADS)

    Conny, J. M.; Collins, S. M.; Anderson, I.; Herzing, A.

    2010-12-01

    Carbon-containing atmospheric particles may either absorb solar or outgoing long-wave radiation or scatter solar radiation, and thus, affect Earth’s radiative balance in multiple ways. Light-absorbing carbon that is common in urban air particles such as industrial coke dust, road dust, and diesel soot, often exists in the same particle with other phases that contain, for example, aluminum, calcium, iron, and sulfur. While the optical properties of atmospheric particles in general depend on overall particle size and shape, the inhomogeneity of chemical phases within internally-mixed particles may also greatly affect particle optical properties. In this study, a series of microscopic approaches were used to identify individual light-absorbing coarse-mode particles and to assess their interior structure and composition. Particle samples were collected in 2004 from one of the U.S. EPA’s Los Angeles Particulate Matter Supersites, and were likely affected substantially by road dust and construction dust. First, bright-field and dark-field light microscopy and computer-controlled scanning electron microscopy (SEM) with energy-dispersive x-ray spectroscopy (EDX) were used to distinguish predominantly light-absorbing carbonaceous particles from other particle types such as mineral dust, sea salt, and brake wear. Second, high-resolution SEM-EDX elemental mapping of individual carbonaceous particles was used to select particles with additional elemental phases that exhibited spatial inhomogeneity. Third, focused ion-beam SEM (FIB-SEM) with EDX was used to slice through selected particles to expose interior surfaces and to determine the spatial distribution of element phases throughout the particles. Fourth, study of the interior phases of a particle was augmented by the transmission electron microscopy (TEM) of a thin section of the particle prepared by FIB-SEM. Here, electron energy loss spectroscopy with TEM was used to study chemical bonding in the carbonaceous phase

  10. Multi-target determination of organic ultraviolet absorbents in organism tissues by ultrasonic assisted extraction and ultra-high performance liquid chromatography-tandem mass spectrometry.

    PubMed

    Peng, Xianzhi; Jin, Jiabin; Wang, Chunwei; Ou, Weihui; Tang, Caiming

    2015-03-06

    A sensitive and reliable method was developed for multi-target determination of 13 most widely used organic ultraviolet (UV) absorbents (including UV filters and UV stabilizers) in aquatic organism tissues. The organic UV absorbents were extracted using ultrasonic-assisted extraction, purified via gel permeation chromatography coupled with silica gel column chromatography, and determined by ultra-high performance liquid chromatography-tandem mass spectrometry. Recoveries of the UV absorbents from organism tissues mostly ranged from 70% to 120% from fish filet with satisfactory reproducibility. Method quantification limits were 0.003-1.0ngg(-1) dry weight (dw) except for 2-ethylhexyl 4-methoxycinnamate. This method has been applied to analysis of the UV absorbents in wild and farmed aquatic organisms collected from the Pearl River Estuary, South China. 2-Hydroxy-4-methoxybenzophenone and UV-P were frequently detected in both wild and farmed marine organisms at low ngg(-1)dw. 3-(4-Methylbenzylidene)camphor and most of the benzotriazole UV stabilizers were also frequently detected in maricultured fish. Octocrylene and 2-ethylhexyl 4-methoxycinnamate were not detected in any sample. This work lays basis for in-depth study about bioaccumulation and biomagnification of the UV absorbents in marine environment.

  11. Ultraviolet Waves

    ERIC Educational Resources Information Center

    Molde, Trevor

    1973-01-01

    Outlines the discovery and nature of ultraviolet light, discusses some applications for these wavelengths, and describes a number of experiments with ultraviolet radiation suitable for secondary school science classes. (JR)

  12. Fluorescein filled photonic crystal fiber sensor for simultaneous ultraviolet light and temperature monitoring

    NASA Astrophysics Data System (ADS)

    Tatar, Peter; Kacik, Daniel; Tarjanyi, Norbert

    2016-07-01

    We present a novel structure composed of a photonic crystal fiber filled with fluorescein dissolved in water spliced between two conventional multimode fibers. Based on unique features of the fluorescein luminescence it is possible to adjust its emission spectrum to required spectral region. With increasing value of the fluorescein solvent pH factor, the peak wavelength of the emission spectrum is shifting to longer wavelength values. Since the excitation spectrum of fluorescein is relatively wide, this optical fiber sensor could be used for an efficient ultraviolet light monitoring. The detection limit at the level 0.24 mW with 490 nm excitation wavelength is presented. Moreover the emission spectrum is temperature sensitive what provides possibility of simultaneous ultraviolet light and temperature monitoring. Also the temperature sensitivity of the structure based on intermodal interference investigation for a compensation purposes and structure usage as spectrum enlarger are outlined.

  13. [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.

  14. Ultra-violet light-emitting diode calibration system for timing large area scintillation detectors

    NASA Astrophysics Data System (ADS)

    Naumov, P. Yu; Runtso, M. F.; Naumov, P. P.; Maklyaev, E. F.; Kaplin, V. A.; Fomin, V. S.; Razzhivin, I. S.; Melikyan, Yu A.

    2017-01-01

    Timing large area plastic scintillation detectors are developing for the space gamma-ray telescopes now. For the in-flight calibration of these detectors the use of ultra-violet light-emitting diode, irradiating the 1 m long detector module at the center of its lateral side is suggested. The results of the measurements show the possibility of this calibration system implementation as for amplitude as for timing properties monitoring.

  15. Measurements of the light-absorbing material inside cloud droplets and its effect on cloud albedo

    NASA Technical Reports Server (NTRS)

    Twohy, C. H.; Clarke, A. D.; Warren, Stephen G.; Radke, L. F.; Charleson, R. J.

    1990-01-01

    Most of the measurements of light-absorbing aerosol particles made previously have been in non-cloudy air and therefore provide no insight into aerosol effects on cloud properties. Here, researchers describe an experiment designed to measure light absorption exclusively due to substances inside cloud droplets, compare the results to related light absorption measurements, and evaluate possible effects on the albedo of clouds. The results of this study validate those of Twomey and Cocks and show that the measured levels of light-absorbing material are negligible for the radiative properties of realistic clouds. For the measured clouds, which appear to have been moderately polluted, the amount of elemental carbon (EC) present was insufficient to affect albedo. Much higher contaminant levels or much larger droplets than those measured would be necessary to significantly alter the radiative properties. The effect of the concentrations of EC actually measured on the albedo of snow, however, would be much more pronounced since, in contrast to clouds, snowpacks are usually optically semi-infinite and have large particle sizes.

  16. Spectral sensitivity of juvenile chub mackerel (Scomber japonicus) in visible and ultraviolet light.

    PubMed

    Matsumoto, Taro; Ihara, Hiroshi; Ishida, Yoshinari; Yamamoto, Shinji; Murata, Osamu; Ishibashi, Yasunori

    2010-03-01

    Although chub mackerel (Scomber japonicus) is widely distributed all over the world, the relevance of its visual sensitivity to its ecology is not yet fully understood. We investigated spectral sensitivity in juvenile chub mackerel in the range of ultraviolet (UV) to visible light (369-652 nm) by electroretinogram (ERG) using light-emitting diodes (LEDs). Sensitivity peaked at a wavelength of approximately 482 nm in dark-adapted fish and 525 nm in light-adapted fish. A secondary sensitivity peak in the UV range at approximately 382 nm was found in both dark- and light-adapted fish. The UV sensitivity of chub mackerel may be attributable to UV transmissibility of the optical media and to the presence of a beta-band of visible light-sensitive visual pigments, and not to an alpha-band of UV visual pigments. This UV sensitivity may be useful for feeding or communication with other fishes.

  17. Lipid rafts mediate ultraviolet light-induced Fas aggregation in M624 melanoma cells.

    PubMed

    Elyassaki, Walid; Wu, Shiyong

    2006-01-01

    Ultraviolet light (UV) induces aggregation of Fas-receptor through a Fas-ligand-independent pathway. However, the mechanism of ultraviolet light-induced Fas-receptor aggregation is not known. In this report, we show that lipid rafts mediate ultraviolet light-induced aggregation of Fas. Our data show that UV induces a redistribution of Fas-receptor in a 25-5% Optiprep continuous gradient. The amount of Fas-receptorS is significantly increased in a gradient fraction that contain lipid rafts and is associated with an increase of FADD and caspase-8. Our data also show that the active dimeric form of caspase-8 (p44/p41) is increased in the lipid raft fraction. In addition, our data show that cholesterol, a major component of lipid rafts, is significantly reduced in only the lipid raft fractions after UV-irradiation. However, ceramide, another major lipid raft component, is increased evenly in all gradient fractions after UV-irradiation. These results suggest that UV alters the composition of major lipid raft components, which leads to the recruitment of Fas-receptor and FADD, with subsequent activation of caspase-8. Based on our results, we propose a novel mechanism by which UV induces apoptosis through a membrane lipid raft-mediated signaling pathway.

  18. White-Light-Induced Collective Heating of Gold Nanocomposite/Bombyx mori Silk Thin Films with Ultrahigh Broadband Absorbance.

    PubMed

    Tsao, Shao Hsuan; Wan, Dehui; Lai, Yu-Sheng; Chang, Ho-Ming; Yu, Chen-Chieh; Lin, Keng-Te; Chen, Hsuen-Li

    2015-12-22

    This paper describes a systematic investigation of the phenomenon of white-light-induced heating in silk fibroin films embedded with gold nanoparticles (Au NPs). The Au NPs functioned to develop an ultrahigh broadband absorber, allowing white light to be used as a source for photothermal generation. With an increase of the Au content in the composite films, the absorbance was enhanced significantly around the localized surface plasmon resonance (LSPR) wavelength, while non-LSPR wavelengths were also increased dramatically. The greater amount of absorbed light increased the rate of photoheating. The optimized composite film exhibited ultrahigh absorbances of approximately 95% over the spectral range from 350 to 750 nm, with moderate absorbances (>60%) at longer wavelengths (750-1000 nm). As a result, the composite film absorbed almost all of the incident light and, accordingly, converted this optical energy to local heat. Therefore, significant temperature increases (ca. 100 °C) were readily obtained when we irradiated the composite film under a light-emitting diode or halogen lamp. Moreover, such composite films displayed linear light-to-heat responses with respect to the light intensity, as well as great photothermal stability. A broadband absorptive film coated on a simple Al/Si Schottky diode displayed a linear, significant, stable photo-thermo-electronic effect in response to varying the light intensity.

  19. Black carbon and other light-absorbing impurities in the Andes of Northern Chile

    NASA Astrophysics Data System (ADS)

    Rowe, P. M.; Cordero, R.; Warren, S. G.; Pankow, A.; Jorquera, J.; Schrempf, M.; Doherty, S. J.; Cabellero, M.; Carrasco, J. F.; Neshyba, S.

    2015-12-01

    Black carbon (BC) and other light-absorbing impurities in snow absorb solar radiation and thus have the potential to accelerate glacial retreat and snowmelt. In Chile, glaciers and seasonal snow are important sources of water for irrigation and domestic uses. In July 2015 (Austral winter) we sampled snow in the western Andes in a north-south transect of Chile from 18 S to 34 S. Most of the sampled snow had fallen during a single synoptic event, during 11-13 July. The snow was melted and passed through 0.4 micrometer nuclepore filters. Preliminary estimates indicate that (1) the ratio of BC to dust in snow increases going south from Northern to Central Chile, and (2) in snow sampled during the two weeks following the snowstorm, the impurities were concentrated in the upper 5 cm of snow, indicating that the surface layer became polluted over time by dry deposition.

  20. Vacuum ultraviolet light source utilizing rare gas scintillation amplification sustained by photon positive feedback

    NASA Technical Reports Server (NTRS)

    Aprile, Elena (Inventor); Chen, Danli (Inventor)

    1995-01-01

    A source of light in the vacuum ultraviolet (VUV) spectral region includes a reflective UV-sensitive photocathode supported in spaced parallel relationship with a mesh electrode within a rare gas at low pressure. A high positive potential applied to the mesh electrode creates an electric field which causes drifting of free electrons occurring between the electrodes and producing continuous VUV light output by electric field-driven scintillation amplification sustained by positive photon feedback mediated by photoemission from the photocathode. In one embodiment the lamp emits a narrow-band continuum peaked at 175 nm.

  1. Disrupting the Transmission of Influenza A: Face Masks and Ultraviolet Light as Control Measures

    PubMed Central

    Weiss, Martin Meyer; Weiss, Peter D.; Weiss, Danielle E.; Weiss, Joseph B.

    2007-01-01

    In the event of an influenza pandemic, where effective vaccine and antiviral drugs may be lacking, disrupting environmental transmission of the influenza virus will be the only viable strategy to protect the public. We discuss 2 such modalities, respirators (face masks) and ultraviolet (UV) light. Largely overlooked, the potential utility of each is underappreciated. The effectiveness of disposable face masks may be increased by sealing the edges of the mask to the face. Reusable masks should be stockpiled, because the supply of disposable masks will likely prove inadequate. UV light, directed overhead, may be beneficial in hospitals and nursing homes. PMID:17413061

  2. Method for outlier detection: a tool to assess the consistency between laboratory data and ultraviolet-visible absorbance spectra in wastewater samples.

    PubMed

    Zamora, D; Torres, A

    2014-01-01

    Reliable estimations of the evolution of water quality parameters by using in situ technologies make it possible to follow the operation of a wastewater treatment plant (WWTP), as well as improving the understanding and control of the operation, especially in the detection of disturbances. However, ultraviolet (UV)-Vis sensors have to be calibrated by means of a local fingerprint laboratory reference concentration-value data-set. The detection of outliers in these data-sets is therefore important. This paper presents a method for detecting outliers in UV-Vis absorbances coupled to water quality reference laboratory concentrations for samples used for calibration purposes. Application to samples from the influent of the San Fernando WWTP (Medellín, Colombia) is shown. After the removal of outliers, improvements in the predictability of the influent concentrations using absorbance spectra were found.

  3. Efficacy of ultraviolet light (UV) and UV-ozone as an intervention to reduce pathogens-contaminated fresh beef

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Although numerous chemical interventions have been implemented and validated to decontaminate meat and meat products during the harvesting process, more novel technologies are under development. Ultraviolet light (UV) ionizing irradiation has been used extensively in pharmaceutical and medical devi...

  4. Capillary scale light emitting diode based multi-reflection absorbance detector.

    PubMed

    Mishra, Santosh K; Dasgupta, Purnendu K

    2007-12-19

    We describe a light emitting diode (LED) based multi-reflection capillary scale absorbance detector based on both square and round capillaries and compare their performance with a conventional single-pass on-tube detector. The optical path length is extended by silver coating, the external surface of the capillary. The reflective geometry has been reported to be less prone to artifacts induced by refractive index changes; we do find this to be true. Although the detection volume/illuminated volume is increased some, a multi-reflection cell based on a 180 microm bore capillary with a approximately 2-cm long illuminated volume shows over a 50-fold gain in signal-to-noise (S/N) compared to a single-pass on-tube configuration with the same capillary. The limit of detection (LOD) is 4.4 fmol (2.6 pg, 1 microL of 22.0 nM injected dye) BTB under pulseless (pneumatic) flow conditions. The cells behave as multipath devices where the effective path lengths are greater at low absorbance values. In our experiments, where non-coherent light is launched through optical fibers that are large compared to capillary bore dimensions, increase in the effective path length of the cell do not occur in a predictable fashion with the angle of incidence of the light beam. Although the effective path length almost linearly increases with increasing distance between the light entry and exit windows, the absolute values of the effective path lengths are always lower than this physical distance, suggesting that after some passage through the solution, light largely travels through or along the glass wall. Square capillaries have better light transmission and offer some performance advantages. Multi-reflection cells can indeed be of value for sensitive detection in microflow systems.

  5. Scavenging insoluble light-absorbing particulates (ILAP) in seasonal snow over northern China

    NASA Astrophysics Data System (ADS)

    Wang, X.; Huang, J.

    2013-12-01

    It has been long believed that Black Carbon (BC) from biomass burning, fossil fuel and biofuel plays an important role in the earth's system through its climate effect. Compared with other insoluble light-absorbing particulates (ILAP), BC is a main component of the most effective light-absorbing particulates, which can dominates the absorption of solar radiation at the visible wavelengths. Furthermore, once deposits on snow, it could significant reduces the snow reflectance and accelerate the snow melting, therefore, it is considered as the second most important component as the CO2 to affect the globe warming. Although several experiments have already been performed for collecting and measuring the scavenging BC in snow on a global scale. Little attention has been given to the quantitative measurements of ILAP deposit on the snowpack at mid-latitude regions in Asia, especially over Northern China. Recently, there are two field campaigns were conducted in January and February 2010 and 2012 to measuring the ILAP in snow across northern China. About 700 snow samples were collected at 84 sites in seven provinces. The BC mass fractions in seasonal snow across northern Xinjiang have a median value of 70 ng g-1, and the concentrations of BC were in the remote northeast on the border of Siberia, with a median concentration in surface snow of 120 ng g-1. South of this, in the industrial northeast, the median snow BC concentration was 1200 ng g-1. In the northeast, snow particulate light absorption was dominated by BC. Across the grassland of Inner Mongolia, OC, likely mostly from local soil, dominates light absorption, with median BC concentrations of 340 ng g-1 responsible for only about one third of total particulate light absorption. In the Qilian Mountains, at the northern boundary of the Tibetan Plateau, snow particulate light absorption is dominated by local soil and desert dust.

  6. Daily changes in ultraviolet light levels can synchronize the circadian clock of bumblebees (Bombus terrestris).

    PubMed

    Chittka, Lars; Stelzer, Ralph J; Stanewsky, Ralf

    2013-05-01

    Endogenous circadian clocks are synchronized to the 24-h day by external zeitgebers such as daily light and temperature cycles. Bumblebee foragers show diurnal rhythms under daily light:dark cycles and short-period free-running circadian rhythms in constant light conditions in the laboratory. In contrast, during the continuous light conditions of the arctic summer, they show robust 24-h rhythms in their foraging patterns, meaning that some external zeitgeber must entrain their circadian clocks in the presence of constant light. Although the sun stays above the horizon for weeks during the arctic summer, the light quality, especially in the ultraviolet (UV) range, exhibits pronounced daily changes. Since the photoreceptors and photopigments that synchronize the circadian system of bees are not known, we tested if the circadian clocks of bumblebees (Bombus terrestris) can be entrained by daily cycles in UV light levels. Bumblebee colonies were set up in the laboratory and exposed to 12 h:12 h UV + :UV- cycles in otherwise continuous lighting conditions by placing UV filters on their foraging arenas for 12 h each day. The activity patterns of individual bees were recorded using fully automatic radiofrequency identification (RFID). We found that colonies manipulated in such a way showed synchronized 24-h rhythms, whereas simultaneously tested control colonies with no variation in UV light levels showed free-running rhythms instead. The results of our study show that bumblebee circadian rhythms can indeed be synchronized by daily cycles in ambient light spectral composition.

  7. Webinar Presentation: Black Carbon and Other Light-absorbing Particles in Snow in Central North America and North China

    EPA Pesticide Factsheets

    This presentation, Black Carbon and Other Light-absorbing Particles in Snow in Central North America and North China, was given at the STAR Black Carbon 2016 Webinar Series: Accounting for Impact, Emissions, and Uncertainty held on Nov. 7, 2016.

  8. Synthesis of Dyed Monodisperse Poly(methylmethacrylate) Colloids for the Preparation of Submicron Periodic Light Absorbing Arrays.

    DTIC Science & Technology

    1995-07-05

    refractive index. This forms a novel submicron periodic system where a body - centered cubic array of absorbers interact with electromagnetic radiation with little scattering or diffraction of the incident light. jg p.1

  9. Light-absorbing Aerosol Properties in the Kathmandu Valley during SusKat-ABC Field Campaign

    NASA Astrophysics Data System (ADS)

    Kim, S.; Yoon, S.; Kim, J.; Cho, C.; Jung, J.

    2013-12-01

    Light-absorbing aerosols, such as black carbon (BC), are major contributors to the atmospheric heating and the reduction of solar radiation reaching at the earth's surface. In this study, we investigate light-absorption and scattering properties of aerosols (i.e., BC mass concentration, aerosol solar-absorption/scattering efficiency) in the Kathmandu valley during Sustainable atmosphere for the Kathmandu valley (SusKat)-ABC campaign, from December 2012 to February 2013. Kathmandu City is among the most polluted cities in the world. However, there are only few past studies that provide basic understanding of air pollution in the Kathmandu Valley, which is not sufficient for designing effective mitigation measures (e.g., technological, financial, regulatory, legal and political measures, planning strategies). A distinct diurnal variation of BC mass concentration with two high peaks observed during wintertime dry monsoon period. BC mass concentration was found to be maximum around 09:00 and 20:00 local standard time (LST). Increased cars and cooking activities including substantial burning of wood and other biomass in the morning and in the evening contributed to high BC concentration. Low BC concentrations during the daytime can be explain by reduced vehicular movement and cooking activities. Also, the developmements of the boundary layer height and mountain-valley winds in the Kathmandu Valley paly a crucial role in the temproal variation of BC mass concentrations. Detailed radiative effects of light-absorbing aerosols will be presented.

  10. Light shift from ultraviolet to near infrared light: Cerenkov luminescence with gold nanocluster - near infrared (AuNc-NIR) conjugates

    NASA Astrophysics Data System (ADS)

    Yoo, Su Woong; Mun, Hyoyoung; Oh, Gyungseok; Ryu, Youngjae; Kim, Min-Gon; Chung, Euiheon

    2015-03-01

    Cerenkov luminescence (CL) is generated when a charged particle moves faster than the speed of light in dielectric media. Recently CL imaging becomes an emerging technique with the use of radioisotopes. However, due to relatively weak blue light production and massive tissue attenuation, CL has not been applied widely. Therefore, we attempted to shift the CL emission to more near infrared (NIR) spectrum for better tissue penetration by using Cerenkov Radiation Energy Transfer (CRET). Gold nanoclusters were conjugated with NIR dye molecules (AuNc-IR820 and AuNc-ICG) to be activated with ultraviolet light. We found optimal conjugate concentrations of AuNc-NIR conjugates by spectroscopy system to generate maximal photon emission. When exposed by ultraviolet light, the emission of NIR light from the conjugates were verified. In quantitative analysis, AuNc-NIR conjugates emit brighter light signal than pure AuNc. This result implies that NIR fluorescent dyes (both IR820 and ICG) can be excited by the emission from AuNc. Following the above baseline experiment, we mixed F-18 fluorodeoxyglucose (F-18 FDG) radioisotope to the AuNc- NIR conjugates, to confirm NIR emission induced from Cerenkov radiation. Long pass filter was used to block Cerenkov luminescence and to collect the emission from AuNc-NIR conjugates. Instead of one long exposure imaging with CCD, we used multiple frame scheme to eliminate gamma radiation strike in each frame prior to combination. In summary, we obtained NIR emission light from AuNc-NIR conjugated dyes that is induced from CL. We plan to perform in vivo small animal imaging with these conjugates to assess better tissue penetration.

  11. Nitride deep-ultraviolet light-emitting diodes with microlens array

    NASA Astrophysics Data System (ADS)

    Khizar, M.; Fan, Z. Y.; Kim, K. H.; Lin, J. Y.; Jiang, H. X.

    2005-04-01

    We report on the fabrication of 280-nm AlGaN-based deep-ultraviolet light-emitting diodes (UV LEDs) on sapphire substrates with an integrated microlens array. Microlenses with a diameter of 12μm were fabricated on the sapphire substrate by resist thermal reflow and plasma dry etching. LED devices were flip-chip bonded on high thermal conductive AlN ceramic submounts to improve the thermal dissipation, and the emitted UV light was extracted through the sapphire substrates. With the integrated microlens array, a 55% enhancement in the output power at 20-mA dc driving was achieved compared with the same LED without microlens. The light extraction enhancement is the result of the reduced internal reflections of the light caused by the microlens surface profile.

  12. Ultraviolet Plasmonic Aluminium Nanoparticles for Highly Efficient Light Incoupling on Silicon Solar Cells

    PubMed Central

    Zhang, Yinan; Cai, Boyuan; Jia, Baohua

    2016-01-01

    Plasmonic metal nanoparticles supporting localized surface plasmon resonances have attracted a great deal of interest in boosting the light absorption in solar cells. Among the various plasmonic materials, the aluminium nanoparticles recently have become a rising star due to their unique ultraviolet plasmonic resonances, low cost, earth-abundance and high compatibility with the complementary metal-oxide semiconductor (CMOS) manufacturing process. Here, we report some key factors that determine the light incoupling of aluminium nanoparticles located on the front side of silicon solar cells. We first numerically study the scattering and absorption properties of the aluminium nanoparticles and the influence of the nanoparticle shape, size, surface coverage and the spacing layer on the light incoupling using the finite difference time domain method. Then, we experimentally integrate 100-nm aluminium nanoparticles on the front side of silicon solar cells with varying silicon nitride thicknesses. This study provides the fundamental insights for designing aluminium nanoparticle-based light trapping on solar cells. PMID:28335223

  13. Ultraviolet Plasmonic Aluminium Nanoparticles for Highly Efficient Light Incoupling on Silicon Solar Cells.

    PubMed

    Zhang, Yinan; Cai, Boyuan; Jia, Baohua

    2016-05-24

    Plasmonic metal nanoparticles supporting localized surface plasmon resonances have attracted a great deal of interest in boosting the light absorption in solar cells. Among the various plasmonic materials, the aluminium nanoparticles recently have become a rising star due to their unique ultraviolet plasmonic resonances, low cost, earth-abundance and high compatibility with the complementary metal-oxide semiconductor (CMOS) manufacturing process. Here, we report some key factors that determine the light incoupling of aluminium nanoparticles located on the front side of silicon solar cells. We first numerically study the scattering and absorption properties of the aluminium nanoparticles and the influence of the nanoparticle shape, size, surface coverage and the spacing layer on the light incoupling using the finite difference time domain method. Then, we experimentally integrate 100-nm aluminium nanoparticles on the front side of silicon solar cells with varying silicon nitride thicknesses. This study provides the fundamental insights for designing aluminium nanoparticle-based light trapping on solar cells.

  14. Methods and apparatus for use with extreme ultraviolet light having contamination protection

    DOEpatents

    Chilese, Francis C.; Torczynski, John R.; Garcia, Rudy; Klebanoff, Leonard E.; Delgado, Gildardo R.; Rader, Daniel J.; Geller, Anthony S.; Gallis, Michail A.

    2016-07-12

    An apparatus for use with extreme ultraviolet (EUV) light comprising A) a duct having a first end opening, a second end opening and an intermediate opening intermediate the first end opening the second end opening, B) an optical component disposed to receive EUV light from the second end opening or to send light through the second end opening, and C) a source of low pressure gas at a first pressure to flow through the duct, the gas having a high transmission of EUV light, fluidly coupled to the intermediate opening. In addition to or rather than gas flow the apparatus may have A) a low pressure gas with a heat control unit thermally coupled to at least one of the duct and the optical component and/or B) a voltage device to generate voltage between a first portion and a second portion of the duet with a grounded insulative portion therebetween.

  15. Effect of ultraviolet light on toxicity of the PAH fluoranthene to freshwater organisms

    SciTech Connect

    Brooke, L.T.; Cox, D.; Kahl, M.; Spehar, R.L.

    1994-12-31

    Certain polyaromatic hydrocarbons (PAHs) can be activated by irradiation with ultraviolet light in the near UV waveband to increase their biocidal qualities. Fluoranthene is one of the PAHs that has this capacity. Ten species of freshwater animals and one species of freshwater plant were acutely exposed to several concentrations of fluoranthene in the presence of additional UV light and to standard light conditions. Tests were conducted using flow-through static or renewal techniques. Fluoranthene concentrations were measured using high pressure liquid chromatography. UV light was produced by UV-emitting fluorescent lamps. UV-C was removed from the spectrum by cellulose triacetate filters. Separate measurements were made of spectral ranges 310 to 390, 265 to 328 and < 320 nm. All species tested except for a dragonfly, Ophiogomphus sp. were more sensitive to fluoranthene in the presence of UV light ranging from 449 to 926 {mu}W/CM{sup 2} than the same species exposed to this chemical in tests using standard light conditions. Sensitivity increased by factors of {<=}32 times in these tests. Two species were tested for effects of UV light during chronic exposure. The cladoceran, Daphnia magna, showed a 17.1 fold increase in sensitivity to fluoranthene due to UV light and the fathead minnow showed a 5.77 fold increase. Results show that water quality criteria for fluoranthene should be adjusted for UV light effects.

  16. A high-performance and cost-effective grating coupler for ultraviolet light

    NASA Astrophysics Data System (ADS)

    Zhang, Jingjing; Chen, Dingbo; Yang, Junbo; Chang, Shengli; Zhang, Hailiang; Jia, Honghui

    2015-10-01

    The ultraviolet (UV) light wavelengths, typically defined to range from10-400nm, have proven to be useful for a number of applications, such as astronomy, biology, medicine and so on. It is important for us to study on the UV and related devices. In this paper, a novel and effective grating coupler for ultraviolet light was reported, which can couple efficiently ultraviolet light from fiber to waveguide at the wavelength of 300nm. The grating coupler was based on the oxide layer of silicon surface, because ultraviolet light can be transmitted pure silicon dioxide (SiO2) with low loss. Based on Bragg condition of grating, we use FDTD method to simulate and design the grating parameters operated under TM polarization. Using our optimization design parameters (period T, incident angle θ, filling factor f and etching height h) to optimize the mode matching between the fiber and the grating region, a relatively high coupling efficiency was obtained for the fiber and waveguide interface. In our design, filling factor f=0.55, period T=280nm etching height H=110nm, incident angle θ=11° can be realized in the process of manufacture. But coupling efficiency are sensitivity to the range of period of grating and incident angle θ, which increase the difficulty of processing and experiment, the process of technology and operation need high precision. Consequently, we the coupling efficiency can be largely increased and beyond 88.5% at center wavelength of 296nm and 1dB bandwidth, in which the theory analysis and the simulation results are in good agreement and coupling efficiency is the highest for this kind of coupler reported as we known. This kind submicron-sized SiO2 waveguides that can be fabricated by mature CMOS-compatible processes are showing promise for realistic dense photonic integrated circuit (PIC) in various applications including optical communications, optical interconnects, signal processing and sensing. The gratings open the path to pure silicon dioxide

  17. Fully inorganic oxide-in-oxide ultraviolet nanocrystal light emitting devices.

    PubMed

    Brovelli, Sergio; Chiodini, Norberto; Lorenzi, Roberto; Lauria, Alessandro; Romagnoli, Marco; Paleari, Alberto

    2012-02-21

    The development of integrated photonics and lab-on-a-chip platforms for environmental and biomedical diagnostics demands ultraviolet electroluminescent materials with high mechanical, chemical and environmental stability and almost complete compatibility with existing silicon technology. Here we report the realization of fully inorganic ultraviolet light-emitting diodes emitting at 390 nm with a maximum external quantum efficiency of ~0.3%, based on SnO(2) nanoparticles embedded in SiO(2) thin films obtained from a solution-processed method. The fabrication involves a single deposition step onto a silicon wafer followed by a thermal treatment in a controlled atmosphere. The fully inorganic architecture ensures superior mechanical robustness and optimal chemical stability in organic solvents and aqueous solutions. The versatility of the fabrication process broadens the possibility of optimizing this strategy and extending it to other nanostructured systems for designed applications, such as active components of wearable health monitors or biomedical devices.

  18. Calibration of a microchannel plate based extreme ultraviolet grazing incident spectrometer at the Advanced Light Source.

    PubMed

    Bakeman, M S; van Tilborg, J; Sokollik, T; Baum, D; Ybarrolaza, N; Duarte, R; Toth, C; Leemans, W P

    2010-10-01

    We present the design and calibration of a microchannel plate based extreme ultraviolet spectrometer. Calibration was performed at the Advance Light Source (ALS) at the Lawrence Berkeley National Laboratory (LBNL). This spectrometer will be used to record the single shot spectrum of radiation emitted by the tapered hybrid undulator (THUNDER) undulator installed at the LOASIS GeV-class laser-plasma-accelerator. The spectrometer uses an aberration-corrected concave grating with 1200 lines/mm covering 11-62 nm and a microchannel plate detector with a CsI coated photocathode for increased quantum efficiency in the extreme ultraviolet. A touch screen interface controls the grating angle, aperture size, and placement of the detector in vacuum, allowing for high-resolution measurements over the entire spectral range.

  19. A simple sub-nanosecond ultraviolet light pulse generator with high repetition rate and peak power.

    PubMed

    Binh, P H; Trong, V D; Renucci, P; Marie, X

    2013-08-01

    We present a simple ultraviolet sub-nanosecond pulse generator using commercial ultraviolet light-emitting diodes with peak emission wavelengths of 290 nm, 318 nm, 338 nm, and 405 nm. The generator is based on step recovery diode, short-circuited transmission line, and current-shaping circuit. The narrowest pulses achieved have 630 ps full width at half maximum at repetition rate of 80 MHz. Optical pulse power in the range of several hundreds of microwatts depends on the applied bias voltage. The bias voltage dependences of the output optical pulse width and peak power are analysed and discussed. Compared to commercial UV sub-nanosecond generators, the proposed generator can produce much higher pulse repetition rate and peak power.

  20. Calibration of a microchannel plate based extreme ultraviolet grazing incident spectrometer at the Advanced Light Source

    SciTech Connect

    Bakeman, M. S.; Tilborg, J. van; Sokollik, T.; Baum, D.; Ybarrolaza, N.; Duarte, R.; Toth, C.; Leemans, W. P.

    2010-10-15

    We present the design and calibration of a microchannel plate based extreme ultraviolet spectrometer. Calibration was performed at the Advance Light Source (ALS) at the Lawrence Berkeley National Laboratory (LBNL). This spectrometer will be used to record the single shot spectrum of radiation emitted by the tapered hybrid undulator (THUNDER) undulator installed at the LOASIS GeV-class laser-plasma-accelerator. The spectrometer uses an aberration-corrected concave grating with 1200 lines/mm covering 11-62 nm and a microchannel plate detector with a CsI coated photocathode for increased quantum efficiency in the extreme ultraviolet. A touch screen interface controls the grating angle, aperture size, and placement of the detector in vacuum, allowing for high-resolution measurements over the entire spectral range.

  1. Detection of composite resin restorations using an ultraviolet light-emitting diode flashlight during forensic dental identification.

    PubMed

    Guzy, Gerald; Clayton, Mary Ann

    2013-06-01

    With the increased use of composite resin and the decreased use of amalgam as a dental restorative material, the forensic dental identification of unidentified human remains has become more difficult. Various methods have been used to detect the presence of composite resin restorations including dyes, forensic alternative light sources, quantitative light-induced fluorescence, and ultraviolet lights. Although these methods may be helpful, the expense of the equipment, the electrical requirements, and the need for water to wash the dye from the mouth may make these methods impractical especially in a temporary morgue situation during a mass disaster. The fluorescent properties of composite resins, when exposed to ultraviolet light, are well documented. Standard tube ultraviolet lights have been used to detect the presence of composite resin, but these lights are large and bulky, and the tubes are fragile. The development of ultraviolet light emitting diode flashlights has provided forensic odontologists with a tool that is small, inexpensive, and battery operated. The two forensic dental identification cases described here demonstrate the value of ultraviolet light emitting diode flashlights as an adjunct to a careful clinical and radiographic examination.

  2. Effects of ultraviolet radiation, visible light, and infrared radiation on erythema and pigmentation: a review.

    PubMed

    Sklar, Lindsay R; Almutawa, Fahad; Lim, Henry W; Hamzavi, Iltefat

    2013-01-01

    The effects of ultraviolet radiation, visible light, and infrared radiation on cutaneous erythema, immediate pigment darkening, persistent pigment darkening, and delayed tanning are affected by a variety of factors. Some of these factors include the depth of cutaneous penetration of the specific wavelength, the individual skin type, and the absorption spectra of the different chromophores in the skin. UVB is an effective spectrum to induce erythema, which is followed by delayed tanning. UVA induces immediate pigment darkening, persistent pigment darkening, and delayed tanning. At high doses, UVA (primarily UVA2) can also induce erythema in individuals with skin types I-II. Visible light has been shown to induce erythema and a tanning response in dark skin, but not in fair skinned individuals. Infrared radiation produces erythema, which is probably a thermal effect. In this article we reviewed the available literature on the effects of ultraviolet radiation, visible light, and infrared radiation on the skin in regards to erythema and pigmentation. Much remains to be learned on the cutaneous effects of visible light and infrared radiation.

  3. Validation of ultraviolet, infrared, and narrow band light alternate light sources for detection of bruises in a pigskin model.

    PubMed

    Olds, Kelly; Byard, Roger W; Winskog, Calle; Langlois, Neil E I

    2016-12-01

    Alternate light sources such as ultraviolet, narrow band, and infrared have been used in an attempt to reveal the presence of bruising that is not otherwise apparent (inapparent). The following study evaluates the ability of alternate light sources to enhance visibility of bruises by employing an objective assessment of digital photography images in conjunction with histology. A pigskin model was employed with bruises created by injection of blood to be not visible or barely visible (inapparent) under white light. The pigskin was photographed using alternate light source illumination. Images were assessed using the program Fiji(®) to measure enhancement in terms of bruise length (cm). Photography results were compared with histology to confirm the presence of bruising. Violet and blue light sources produced the greatest enhancement, both with a p < 0.0001. Regions that were not bruises were also enhanced with light sources in this study, indicating that light sources are not specific, and that their use to enhance the visibility of bruising should be undertaken with caution.

  4. Densely packed aluminum-silver nanohelices as an ultra-thin perfect light absorber

    PubMed Central

    Jen, Yi-Jun; Huang, Yu-Jie; Liu, Wei-Chih; Lin, Yueh Weng

    2017-01-01

    Metals have been formed into nanostructures to absorb light with high efficiency through surface plasmon resonances. An ultra-thin plasmonic structure that exhibits strong absorption over wide ranges of wavelengths and angles of incidence is sought. In this work, a nearly perfect plasmonic nanostructure is fabricated using glancing angle deposition. The difference between the morphologies of obliquely deposited aluminum and silver nanohelices is exploited to form a novel three-dimensional structure, which is an aluminum-silver nanohelix array on a pattern-free substrate. With a thickness of only 470 nm, densely distributed nanohelices support rod-to-rod localized surface plasmons for broadband and polarization-independent light extinction. The extinctance remains high over wavelengths from 400 nm to 2000 nm and angles of incidence from 0° to 70°. PMID:28045135

  5. Densely packed aluminum-silver nanohelices as an ultra-thin perfect light absorber

    NASA Astrophysics Data System (ADS)

    Jen, Yi-Jun; Huang, Yu-Jie; Liu, Wei-Chih; Lin, Yueh Weng

    2017-01-01

    Metals have been formed into nanostructures to absorb light with high efficiency through surface plasmon resonances. An ultra-thin plasmonic structure that exhibits strong absorption over wide ranges of wavelengths and angles of incidence is sought. In this work, a nearly perfect plasmonic nanostructure is fabricated using glancing angle deposition. The difference between the morphologies of obliquely deposited aluminum and silver nanohelices is exploited to form a novel three-dimensional structure, which is an aluminum-silver nanohelix array on a pattern-free substrate. With a thickness of only 470 nm, densely distributed nanohelices support rod-to-rod localized surface plasmons for broadband and polarization-independent light extinction. The extinctance remains high over wavelengths from 400 nm to 2000 nm and angles of incidence from 0° to 70°.

  6. Colloidal metasurfaces displaying near-ideal and tunable light absorbance in the infrared

    NASA Astrophysics Data System (ADS)

    Rozin, Matthew J.; Rosen, David A.; Dill, Tyler J.; Tao, Andrea R.

    2015-06-01

    Metasurfaces are ultrathin, two-dimensional arrays of subwavelength resonators that have been demonstrated to control the flow of light in ways that are otherwise unattainable with natural materials. These arrays are typically composed of metallic Ag or Au nanostructures shaped like split rings, nanowire pairs or nanorods (commonly referred to as meta-atoms) that are arranged to produce a collective optical response spanning an impressive range of properties, from the perfect absorption of incident light to superresolution imaging. However, metasurfaces pose major challenges in their fabrication over large areas, which can be prohibitively expensive and time consuming using conventional nanolithography techniques. Here we show that differently shaped colloidal nanocrystals can be organized into metasurface architectures using robust, scalable assembly methods. These metasurfaces exhibit extreme in-plane electromagnetic coupling that is strongly dependent on nanocrystal size, shape and spacing. Colloidal metasurfaces that display near-ideal electromagnetic absorbance can be tuned from the visible into the mid-infrared wavelengths.

  7. Characteristics of dissolved organic carbon revealed by ultraviolet/visible absorbance and fluorescence spectroscopy: The current status and future exploration

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Dissolved organic carbon (DOC) is an important research subject for various disciplines. The objectives of this chapter are to review and summarize recent advancement in characterization of DOC by ultraviolet/visible (UV/Vis) and fluorescence spectroscopies and to identify the information gaps for ...

  8. The interplay between assumed morphology and the direct radiative effect of light-absorbing organic aerosol

    NASA Astrophysics Data System (ADS)

    Saleh, Rawad; Adams, Peter J.; Donahue, Neil M.; Robinson, Allen L.

    2016-08-01

    Mie theory is widely employed in aerosol top-of-the-atmosphere direct radiative effect (DRE) calculations and to retrieve the absorptivity of light-absorbing organic aerosol (OA) from measurements. However, when OA is internally mixed with black carbon, it may exhibit complex morphologies whose optical behavior is imperfectly predicted by Mie theory, introducing bias in the retrieved absorptivities. We performed numerical experiments and global radiative transfer modeling (RTM) to investigate the effect of this bias on the calculated absorption and thus the DRE. We show that using true OA absorptivity, retrieved with a realistic representation of the complex morphology, leads to significant errors in DRE when the RTM employs the simplified Mie theory. On the other hand, when Mie theory is consistently applied in both OA absorptivity retrieval and the RTM, the errors largely cancel out, yielding accurate DRE. As long as global RTMs use Mie theory, they should implement parametrizations of light-absorbing OA derived from retrievals based on Mie theory.

  9. Electromagnetically induced transparency of a plasmonic metamaterial light absorber based on multilayered metallic nanoparticle sheets

    PubMed Central

    Okamoto, Koichi; Tanaka, Daisuke; Degawa, Ryo; Li, Xinheng; Wang, Pangpang; Ryuzaki, Sou; Tamada, Kaoru

    2016-01-01

    In this study, we observed the peak splitting of absorption spectra for two-dimensional sheets of silver nanoparticles due to the electromagnetically induced transparency (EIT) effect. This unique optical phenomenon was observed for the multilayered nanosheets up to 20 layers on a metal substrate, while this phenomenon was not observed on a transparent substrate. The wavelength and intensities of the split peaks depend on the number of layers, and the experimental results were well reproduced by the calculation of the Transfer-Matrix method by employing the effective medium approximation. The Ag nanosheets used in this study can act as a plasmonic metamaterial light absorber, which has a such large oscillator strength. This phenomenon is a fundamental optical property of a thin film on a metal substrate but has never been observed because native materials do not have a large oscillator strength. This new type of EIT effect using a plasmonic metamaterial light absorber presents the potential for the development of future optic and photonic technologies. PMID:27824071

  10. Electromagnetically induced transparency of a plasmonic metamaterial light absorber based on multilayered metallic nanoparticle sheets.

    PubMed

    Okamoto, Koichi; Tanaka, Daisuke; Degawa, Ryo; Li, Xinheng; Wang, Pangpang; Ryuzaki, Sou; Tamada, Kaoru

    2016-11-08

    In this study, we observed the peak splitting of absorption spectra for two-dimensional sheets of silver nanoparticles due to the electromagnetically induced transparency (EIT) effect. This unique optical phenomenon was observed for the multilayered nanosheets up to 20 layers on a metal substrate, while this phenomenon was not observed on a transparent substrate. The wavelength and intensities of the split peaks depend on the number of layers, and the experimental results were well reproduced by the calculation of the Transfer-Matrix method by employing the effective medium approximation. The Ag nanosheets used in this study can act as a plasmonic metamaterial light absorber, which has a such large oscillator strength. This phenomenon is a fundamental optical property of a thin film on a metal substrate but has never been observed because native materials do not have a large oscillator strength. This new type of EIT effect using a plasmonic metamaterial light absorber presents the potential for the development of future optic and photonic technologies.

  11. Soot on snow experiments: light-absorbing impurities effect on the natural snowpack

    NASA Astrophysics Data System (ADS)

    Svensson, J.; Virkkula, A.; Meinander, O.; Kivekäs, N.; Hannula, H.-R.; Järvinen, O.; Peltoniemi, J. I.; Gritsevich, M.; Heikkilä, A.; Kontu, A.; Hyvärinen, A.-P.; Neitola, K.; Brus, D.; Dagsson-Waldhauserova, P.; Anttila, K.; Hakala, T.; Kaartinen, H.; Vehkamäki, M.; de Leeuw, G.; Lihavainen, H.

    2015-02-01

    Light-absorbing impurities affect snow and ice via a decrease in albedo and a consequent disturbance to the radiative energy balance. Experimentally, these matters have only been examined in a few studies. Here we present results from a series of experiments in which we deposited different soot concentrations onto natural snow in different regions of Finland, and thereafter monitored the changes of the snowpack through the melting season. Measurements of the particulates in the snow indicated concentrations in the range of thousands of ppb to have clear effects on the snow properties, including the albedo, the physical snow characteristics, and an increased melt rate. For soot concentrations in the hundreds of ppb range, the effects were not as clearly visible, and it was more difficult to attribute the effects solely to the soot on the snow. Comparisons between our experimental data and the widely used Snow, Ice and Aerosol Radiation (SNICAR) model showed a general agreement when the model was specifically tuned to our measurements. This study highlights the importance of additional experimental studies, to further articulate and quantify the effects of light-absorbing impurities on snow.

  12. Electromagnetically induced transparency of a plasmonic metamaterial light absorber based on multilayered metallic nanoparticle sheets

    NASA Astrophysics Data System (ADS)

    Okamoto, Koichi; Tanaka, Daisuke; Degawa, Ryo; Li, Xinheng; Wang, Pangpang; Ryuzaki, Sou; Tamada, Kaoru

    2016-11-01

    In this study, we observed the peak splitting of absorption spectra for two-dimensional sheets of silver nanoparticles due to the electromagnetically induced transparency (EIT) effect. This unique optical phenomenon was observed for the multilayered nanosheets up to 20 layers on a metal substrate, while this phenomenon was not observed on a transparent substrate. The wavelength and intensities of the split peaks depend on the number of layers, and the experimental results were well reproduced by the calculation of the Transfer-Matrix method by employing the effective medium approximation. The Ag nanosheets used in this study can act as a plasmonic metamaterial light absorber, which has a such large oscillator strength. This phenomenon is a fundamental optical property of a thin film on a metal substrate but has never been observed because native materials do not have a large oscillator strength. This new type of EIT effect using a plasmonic metamaterial light absorber presents the potential for the development of future optic and photonic technologies.

  13. An Internet Database of Ultraviolet Continuum Light Curves for Seyfert Galaxies

    NASA Astrophysics Data System (ADS)

    Dunn, Jay P.; Jackson, Brian; Deo, Rajesh P.; Farrington, Chris; Das, Varendra; Crenshaw, D. Michael

    2006-04-01

    Using the Multimission Archive at STScI (MAST), we have extracted spectra and determined continuum light curves for 175 Seyfert galaxies that have been observed with the International Ultraviolet Explorer and the Faint Object Spectrograph on the Hubble Space Telescope. To obtain the light curves as a function of Julian Date, we used fixed bins in the object's rest frame and measured small regions (between 30 and 60 Å) of each spectrum's continuum flux in the range 1150 to 3200 Å. We provide access to the UV light curves and other basic information about the observations in tabular and graphical form via the Internet at http://www.chara.gsu.edu/PEGA/IUE.

  14. Selective irradiation of radicals for biomedical treatment using vacuum ultraviolet light from an excimer lamp

    NASA Astrophysics Data System (ADS)

    Ono, Ryo; Tokumitsu, Yusuke; Zen, Shungo; Yonemori, Seiya

    2014-10-01

    In plasma medicine, radicals are considered to play important roles. However, the medical effect of each radical, such as OH and O, is unknown. To examine the effect of each radical, selective production of radicals is needed. We developed selective production of radicals for biomedical treatment using a vacuum ultraviolet (VUV) light emitted from an excimer lamp. Selective irradiation of OH radicals can be achieved by irradiating the 172-nm VUV light from a Xe2 excimer lamp to a humid helium flow in a quartz tube. The water molecules are strongly photodissociated by the VUV light to produce OH radicals. A photochemical simulation for the selective OH production is developed to calculate the OH density. The calculated OH density is compared with OH density measured using laser-induced fluorescence (LIF). Selective production of other radicals than OH is also discussed.

  15. Discolouration of orthodontic adhesives caused by food dyes and ultraviolet light.

    PubMed

    Faltermeier, Andreas; Rosentritt, Martin; Reicheneder, Claudia; Behr, Michael

    2008-02-01

    Enamel discolouration after debonding of orthodontic attachments could occur because of irreversible penetration of resin tags into the enamel structure. Adhesives could discolour because of food dyes or ultraviolet irradiation. The aim of this study was to investigate the colour stability of adhesives during ultraviolet irradiation and exposure to food colourants. Four different adhesives were exposed in a Suntest CPS+ ageing device to a xenon lamp to simulate natural daylight (Transbond XT, Enlight, RelyX Unicem, and Meron Plus AC). Tomato ketchup, Coca Cola, and tea were chosen as the food colourants. After 72 hours of exposure, colour measurements were performed by means of a spectrophotometer according to the Commission Internationale de l'Eclairage L*a*b* system and colour changes (DeltaE*) were computed. Statistical differences were investigated using two-way analysis of variance (ANOVA) and Friedman test. Unsatisfactory colour stability after in vitro exposure to food colourants and ultraviolet light was observed for the conventional adhesive systems, Transbond XT and Enlight. RelyX Unicem showed the least colour change and the resin-reinforced glass-ionomer cement (GIC), Meron Plus AC, the greatest colour change. The investigated adhesives seem to be susceptible to both internal and external discolouration. These in vitro findings indicate that the tested conventional adhesive systems reveal unsatisfactory colour stability which should be improved to avoid enamel discolouration.

  16. Human fibroblast strain with normal survival but abnormal postreplication repair after ultraviolet light irradiation

    SciTech Connect

    Doniger, J.; Barrett, S.F.; Robbins, J.H.

    1980-08-01

    Postreplication repair has been studied in ultraviolet light (UV-irradiated) fibroblast strains derived from eight apparently normal control donors and seven xeroderma pigmentosum patients. One control donor strain had an intermediate defect in postreplication repair similar to that in excision-deficient xeroderma pigmentosum fibroblasts. However, unlike the xeroderma pigmentosum strains, this control donor strain had normal UV-induced unscheduled DNA synthesis and normal survival after irradiation with UV. This unique fibroblast strain should be useful in studies designed to elucidate the possible role of postreplication repair in UV-induced carcinogenesis and mutagenesis.

  17. Torsional Motion of the Chromophore Catechol following the Absorption of Ultraviolet Light

    NASA Astrophysics Data System (ADS)

    Young, J. D.; Staniforth, M.; Paterson, M. J.; Stavros, V. G.

    2015-06-01

    The ability to probe energy flow in molecules, following the absorption of ultraviolet light, is crucial to unraveling photophysical phenomena. Here we excite a coherent superposition of vibrational states in the first excited electronic state (S1 ) in catechol, resulting in a vibrational wave packet. The observed quantum beats, assigned to superpositions of the low-frequency, and strongly mixed, O-H torsional mode τ2 , elegantly demonstrate how changes in geometry upon photoionization from the S1 state to the ground state of the cation (D0 ) enables one to probe energy flow at the very early stages of photoexcitation in this biological chromophore.

  18. Crystallization and preliminary X-ray crystallographic analysis of a blue-light-absorbing proteorhodopsin.

    PubMed

    Wang, Ning; Wang, Meitian; Gao, Yanyan; Ran, Tingting; Lan, Yanli; Wang, Jian; Xu, Langlai; Wang, Weiwu

    2012-03-01

    Proteorhodopsins (PRs), seven-transmembrane chromoproteins with retinal as a chromophore, are light-driven proton pumps. To elucidate the light-driven proton-pumping mechanism of PRs, a pET28a vector containing the blue-light-absorbing proteorhodopsin (BPR) gene was constructed and the protein was overexpressed in Escherichia coli. The protein was purified by immobilized metal-ion affinity chromatography (IMAC). The purified BPR D97N mutant protein (BPR_D97N) was crystallized using the vapour-diffusion method. Preliminary X-ray diffraction data analysis showed that the crystal belonged to the orthorhombic space group P2(1)2(1)2, with unit-cell parameters a = 161.6, b = 168.6, c = 64.7 Å. A complete data set was collected to 3.3 Å resolution using synchrotron radiation on beamline X06 of the Swiss Light Source (SLS). Molecular replacement was unsuccessful. To solve the structure of BPR_D97N by experimental phasing, selenomethionine-substituted protein crystals were prepared. These crystals diffracted to 3.0 Å resolution and a complete data set was collected on beamline BL17U of the Shanghai Synchrotron Radiation Facility (SSRF). Heavy-atom substructure determination and phasing by SAD clearly showed that the crystal contained five molecules in the asymmetric unit, with a V(M) of 3.26 Å(3) Da(-1) and a solvent content of 62.3%.

  19. 2D Homologous Perovskites as Light-Absorbing Materials for Solar Cell Applications.

    PubMed

    Cao, Duyen H; Stoumpos, Constantinos C; Farha, Omar K; Hupp, Joseph T; Kanatzidis, Mercouri G

    2015-06-24

    We report on the fabrication and properties of the semiconducting 2D (CH3(CH2)3NH3)2(CH3NH3)(n-1)Pb(n)I(3n+1) (n = 1, 2, 3, and 4) perovskite thin films. The band gaps of the series decrease with increasing n values, from 2.24 eV (CH3(CH2)3NH3)2PbI4 (n = 1) to 1.52 eV CH3NH3PbI3 (n = ∞). The compounds exhibit strong light absorption in the visible region, accompanied by strong photoluminescence at room temperature, rendering them promising light absorbers for photovoltaic applications. Moreover, we find that thin films of the semi-2D perovskites display an ultrahigh surface coverage as a result of the unusual film self-assembly that orients the [Pb(n)I(3n+1)](-) layers perpendicular to the substrates. We have successfully implemented this 2D perovskite family in solid-state solar cells, and obtained an initial power conversion efficiency of 4.02%, featuring an open-circuit voltage (V(oc)) of 929 mV and a short-circuit current density (J(sc)) of 9.42 mA/cm(2) from the n = 3 compound. This result is even more encouraging considering that the device retains its performance after long exposure to a high-humidity environment. Overall, the homologous 2D halide perovskites define a promising class of stable and efficient light-absorbing materials for solid-state photovoltaics and other applications.

  20. Psoralens potentiate ultraviolet light-induced inhibition of epidermal growth factor binding

    SciTech Connect

    Laskin, J.D.; Lee, E.; Laskin, D.L.; Gallo, M.A.

    1986-11-01

    The psoralens, when activated by ultraviolet light of 320-400 nm (UVA light), are potent modulators of epidermal cell growth and differentiation. Previously, we reported that, in mammalian cells, these compounds bind to specific saturable high-affinity cellular receptor sites. In the present studies, we demonstrate that binding of psoralens to their receptors followed by UVA light activation is associated with inhibition of epidermal growth factor (EGF) receptor binding. Inhibition of EGF binding, which required UVA light, was rapid and dependent on the dose of UVA light (0.5-2.0 J/cm2), as well as the concentration of psoralens (10 nM to 1 microM). Higher doses of UVA light (2.0-6.0 J/cm2) by themselves were also inhibitory, indicating that psoralens potentiate the UVA-induced inhibition of EGF binding. A number of biologically active analogs of psoralen, including 8-methoxypsoralen, 5-methoxypsoralen, and 4,5',8-trimethylpsoralen, when activated by UVA light, were found to be inhibitors of binding. Inhibition of EGF binding by psoralens was observed in a variety of human and mouse cell culture lines known to possess psoralen receptors. In the epidermal-derived line PAM 212, at least two populations of receptors with different affinities for EGF were found. Psoralens and UVA light selectively inhibited binding to the higher-affinity EGF receptors, an effect analogous to that of the phorbol ester tumor promoters. As observed with phorbol esters, photoactivated psoralens appeared to inhibit EGF binding by an indirect mechanism. These data demonstrate that the psoralens and UVA light have direct biological effects on cell-surface membranes. Since EGF is a growth-regulatory peptide, the ability of psoralens and UVA light to inhibit EGF binding may underlie the biologic effects of these agents in the skin.

  1. Photoeffects of near ultraviolet light upon a polycyclic aromatic hydrocarbon exposed to mouse skin microsomes

    SciTech Connect

    Peirano, W.B.

    1991-01-01

    Near ultraviolet (UV) light has been reported to both enhance and inhibit the tumor incidence in mice dermally exposed to benzo(a)pyrene (BaP) or polycyclic aromatic hydrocarbon (PAH) mixtures. Near UV light interacts with PAHs producing a variety of oxygenated products such as phenols, endoperoxides and quinones. However, little is known about BaP products formed from near UV irradiation of BaP-exposed mouse skin. Therefore, [sup 14]C-BaP was incubated with 3-methylcholanthrene (3-MC) induced C[sub 3]H/HeJ and DBA/2J mouse skin microsomes with or without a 365 nm light source. The results indicated that the concurrent 365 nm light irradiation of induced mouse skin microsomes and BaP greatly enhanced the total conversion of BaP to its products, approximately 3-fold for the C[sub 3]H/HeJ and approximately 7-fold for the DBA/2J mouse microsomes, compared to the induced mouse skin microsomes and BaP alone. HPLC analyses of organic extracts indicated a more than additive enhancement of the formation of most of the individual cochromatographed BaP metabolites due to the combined interaction of 365 nm light with BaP and skin microsomes. Similar interactions were observed using benz(a)anthracene (BaA) in this system. These data show that near UV light alters the metabolic profile of PAHs produced by mouse skin microsomes.

  2. THE FIRST MAXIMUM-LIGHT ULTRAVIOLET THROUGH NEAR-INFRARED SPECTRUM OF A TYPE Ia SUPERNOVA

    SciTech Connect

    Foley, Ryan J.; Marion, G. Howie; Challis, Peter; Kirshner, Robert P.; Berta, Zachory K.; Kromer, Markus; Taubenberger, Stefan; Hillebrandt, Wolfgang; Roepke, Friedrich K.; Ciaraldi-Schoolmann, Franco; Seitenzahl, Ivo R.; Pignata, Giuliano; Stritzinger, Maximilian D.; Filippenko, Alexei V.; Li Weidong; Silverman, Jeffrey M.; Folatelli, Gaston; Hsiao, Eric Y.; Morrell, Nidia I.; Simcoe, Robert A.; and others

    2012-07-01

    We present the first maximum-light ultraviolet (UV) through near-infrared (NIR) Type Ia supernova (SN Ia) spectrum. This spectrum of SN 2011iv was obtained nearly simultaneously by the Hubble Space Telescope at UV/optical wavelengths and the Magellan Baade telescope at NIR wavelengths. These data provide the opportunity to examine the entire maximum-light SN Ia spectral energy distribution. Since the UV region of an SN Ia spectrum is extremely sensitive to the composition of the outer layers of the explosion, which are transparent at longer wavelengths, this unprecedented spectrum can provide strong constraints on the composition of the SN ejecta, and similarly the SN explosion and progenitor system. SN 2011iv is spectroscopically normal, but has a relatively fast decline ({Delta}m{sub 15}(B) = 1.69 {+-} 0.05 mag). We compare SN 2011iv to other SNe Ia with UV spectra near maximum light and examine trends between UV spectral properties, light-curve shape, and ejecta velocity. We tentatively find that SNe with similar light-curve shapes but different ejecta velocities have similar UV spectra, while those with similar ejecta velocities but different light-curve shapes have very different UV spectra. Through a comparison with explosion models, we find that both a solar-metallicity W7 and a zero-metallicity delayed-detonation model provide a reasonable fit to the spectrum of SN 2011iv from the UV to the NIR.

  3. Influence of ultraviolet light on the toxicity of sediments contaminated with polycyclic aromatic hydrocarbons

    SciTech Connect

    Ankley, G.T.; Collyard, S.A. ); Monson, P.D. ); Kosian, P.A. )

    1994-11-01

    Standard 10-d toxicity tests were conducted with freshwater benthic invertebrates using sediments containing a range of concentrations of polycyclic aromatic hydrocarbons (PAHs). The assays were performed both under normal laboratory fluorescent light and ultraviolet (UV) light, which mimicked wavelengths present in sunlight, at about 10% of ambient solar intensity. In sediments with elevated PAH concentrations, tests conducted with UV light resulted in significantly greater mortality of Hyalella azteca (amphipods) and Lumbriculus variegatus (oligochaetes) than tests performed under otherwise comparable conditions with fluorescent light. There also was increased mortality of these two species, relative to controls, when surviving organisms from the 10-d exposures to the PAH-contaminated sediments were placed in clean water under UV light for 2 h. These results suggest that the organisms accumulated PAHs from the test sediments, which were subsequently photoactivated by UV light to excited states more toxic than the ground-state molecules. The phenomenon of photoactivation has been examined for pelagic species exposed to PAHs, but not for benthic organisms exposed to sediment-associated PAHs. The results suggest that failure to consider photoactivation of PAHs by sunlight could result in sediment toxicity test methods or criteria that are underprotective of benthic organisms.

  4. A low-cost low-maintenance ultraviolet lithography light source based on light-emitting diodes.

    PubMed

    Erickstad, M; Gutierrez, E; Groisman, A

    2015-01-07

    A source of collimated ultraviolet (UV) light is a central piece of equipment needed for lithographic fabrication of microfluidic devices. Conventional UV light sources based on high-pressure mercury lamps require considerable maintenance and provide broad-band illumination with intensity that often changes with time. Here we present a source of narrow-band UV light based on an array of nine 365 nm light-emitting diodes (LEDs). Each LED has two dedicated converging lenses, reducing the divergence of light emanating from it to 5.4°. Partial overlap of the areas illuminated by individual LEDs provides UV illumination with a mean intensity of ~1.7 mW cm(-2) and coefficient of variation <3% over a 90 × 90 mm target area. The light source was used to lithographically fabricate micro-reliefs with thicknesses from ~25 to 311 μm with SU8 photoresists. A cumulative irradiation of 370 mJ cm(-2) (4 min exposure) produced reliefs of good quality for all SU8 thicknesses. Polydimethylsiloxane (PDMS) replicas of the SU8 reliefs had microchannels with nearly rectangular cross-sections that were highly consistent over the entire target area, and partitions between the channels had depth to width ratios up to 5. The UV light source has also been successfully used for photolithography with positive photoresists, AZ40XT and SPR-220. The proposed light source is built with a total cost of <$1000, consumes a minimal amount of power, is expected to last for ~50,000 exposures, is maintenance-free, and is particularly appealing for small research-and-development microfluidic fabrication.

  5. Modeling of light absorbing particles in atmosphere, snow and ice in the Arctic

    NASA Astrophysics Data System (ADS)

    Sobhani, N.; Kulkarni, S.; Carmichael, G. R.

    2015-12-01

    Long-range transport of atmospheric particles from mid-latitude sources to the Arctic is the main contributor to the Arctic aerosol loadings and deposition. Black Carbon (BC), Brown Carbon (BrC) and dust are considered of great climatic importance and are the main absorbers of sunlight in the atmosphere. Furthermore, wet and dry deposition of light absorbing particles (LAPs) on snow and ice cause reduction of snow and ice albedo. LAPs have significant radiative forcing and effect on snow albedo. There are high uncertainties in estimating radiative forcing of LAPs. We studied the potential effect of LAPs from different emission source regions and sectors on snow albedo in the Arctic. The transport pathway of LAPs to the Arctic is studies for different high pollution episodes. In this study a modeling framework including Weather Research and Forecasting Model (WRF) and the University of Iowa's Sulfur Transport and dEpostion model(STEM) is used to predict the transport of LAPs from different geographical sources and sectors (i.e. transportation, residential, industry, biomass burning and power) to the Arctic. For assessing the effect of LAP deposition on snow single-layer simulator of the SNow, Ice, and Aerosol Radiation (SNICAR-Online) model was used to derive snow albedo values for snow albedo reduction causes by BC deposition. To evaluate the simulated values we compared the BC concentration in snow with observed values from previous studies including Doherty et al. 2010.

  6. High-performance liquid chromatography - Ultraviolet method for the determination of total specific migration of nine ultraviolet absorbers in food simulants based on 1,1,3,3-Tetramethylguanidine and organic phase anion exchange solid phase extraction to remove glyceride.

    PubMed

    Wang, Jianling; Xiao, Xiaofeng; Chen, Tong; Liu, Tingfei; Tao, Huaming; He, Jun

    2016-06-17

    The glyceride in oil food simulant usually causes serious interferences to target analytes and leads to failure of the normal function of the RP-HPLC column. In this work, a convenient HPLC-UV method for the determination of the total specific migration of nine ultraviolet (UV) absorbers in food simulants was developed based on 1,1,3,3-tetramethylguanidine (TMG) and organic phase anion exchange (OPAE) SPE to efficiently remove glyceride in olive oil simulant. In contrast to the normal ion exchange carried out in an aqueous solution or aqueous phase environment, the OPAE SPE was performed in the organic phase environments, and the time-consuming and challenging extraction of the nine UV absorbers from vegetable oil with aqueous solution could be readily omitted. The method was proved to have good linearity (r≥0.99992), precision (intra-day RSD≤3.3%), and accuracy(91.0%≤recoveries≤107%); furthermore, the lower limit of quantifications (0.05-0.2mg/kg) in five types of food simulants(10% ethanol, 3% acetic acid, 20% ethanol, 50% ethanol and olive oil) was observed. The method was found to be well suited for quantitative determination of the total specific migration of the nine UV absorbers both in aqueous and vegetable oil simulant according to Commission Regulation (EU) No. 10/2011. Migration levels of the nine UV absorbers were determined in 31 plastic samples, and UV-24, UV-531, HHBP and UV-326 were frequently detected, especially in olive oil simulant for UV-326 in PE samples. In addition, the OPAE SPE procedure was also been applied to efficiently enrich or purify seven antioxidants in olive oil simulant. Results indicate that this procedure will have more extensive applications in the enriching or purification of the extremely weak acidic compounds with phenol hydroxyl group that are relatively stable in TMG n-hexane solution and that can be barely extracted from vegetable oil.

  7. Multiple-wavelength spectroscopic quantitation of light-absorbing species in scattering media

    DOEpatents

    Nathel, Howard; Cartland, Harry E.; Colston, Jr., Billy W.; Everett, Matthew J.; Roe, Jeffery N.

    2000-01-01

    An oxygen concentration measurement system for blood hemoglobin comprises a multiple-wavelength low-coherence optical light source that is coupled by single mode fibers through a splitter and combiner and focused on both a target tissue sample and a reference mirror. Reflections from both the reference mirror and from the depths of the target tissue sample are carried back and mixed to produce interference fringes in the splitter and combiner. The reference mirror is set such that the distance traversed in the reference path is the same as the distance traversed into and back from the target tissue sample at some depth in the sample that will provide light attenuation information that is dependent on the oxygen in blood hemoglobin in the target tissue sample. Two wavelengths of light are used to obtain concentrations. The method can be used to measure total hemoglobin concentration [Hb.sub.deoxy +Hb.sub.oxy ] or total blood volume in tissue and in conjunction with oxygen saturation measurements from pulse oximetry can be used to absolutely quantify oxyhemoglobin [HbO.sub.2 ] in tissue. The apparatus and method provide a general means for absolute quantitation of an absorber dispersed in a highly scattering medium.

  8. New approaches to DNA damage and repair: the ultraviolet light example

    SciTech Connect

    Haseltine, W.A.; Gordon, L.K.; Lindan, C.; Lippke, J.; Brash, D.; Lo, K.M.; Royer-Pokora, B.

    1982-01-01

    DNA fragments of defined sequence are used as probes to study DNA damage and repair. The case of ultraviolet light is presented and includes the following: (a) Description of the distribution of cyclobutane pyrimidine dimers within defined DNA sequences. Considerations of the effect of neighboring base composition, dose rate, and double- or single-stranded property of the DNA are discussed. (b) Dissection of the anatomy of the incision event and subsequent repair steps. A three-step incision model for repair of cyclobutane dimers by the Micrococcus luteus repair enzymes will be presented. The steps are (1) recognition of the lesion and N-glycosylase scission, (2) cleavage of the phosphodiester bond 3' to the newly created apyrimidinic site, and (3) scission of the apyrimidinic sugar on the 5' side. (c) Use of human alphoid sequences as indicators of DNA damage in intact human cells. (d) Biological significance of a novel ultraviolet light-induced photoproduct. This photoproduct occurs at pyrimidine-cytosine sequences and may have a significant biological role.

  9. Delayed ultraviolet light-induced cessation of respiration by inadequate aeration of Escherichia coli.

    PubMed

    Joshi, J G; Swenson, P A; Schenley, R L

    1977-02-01

    Inadequately aerated Escherichia coli B/r cultures did not shut their respiration off 60 min after ultraviolet light (52 M/m2 at 254 nm) as they did when well supplied with oxygen. Since cessation of respiaration is associated with cell death, the result suggested that oxygen toxicity by superoxide radicals generated by cell metabolism might be responsible for cell death. The specific activity of superoxide dismutase, which scavenges O2- radicals, increased twofold after 90 min of adequate aeration, but the specific activity of catalase remained constant. Respiration and viability of irradiated cells were affected not at all by the presence of superoxide dismutase and only slightly by the presence of catalase. Metal ions such as Mn2+ and Fe2+ inducers of superoxide dismutase, had no effect on respiration and viability. When irradiated cells were incubated under N2 for 90 min, the respiration, growth, and viability time-course responses were the same as for the cells not exposed to anareobiosis. We conclude that superoxide anions generated at the time of irradiation play no part in cessation delays the ultraviolet light-induced synthesis of proteins responsible for the irreversible cessation of respiration.

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

    PubMed

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

    2015-05-01

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

  11. Infrared Spectra of Acetylene Diluted in Solid Nitrogen upon Irradiation with Vacuum Ultraviolet Light and Electrons

    NASA Astrophysics Data System (ADS)

    Wu, Yu-Jong; Chuang, Shiang-Jiun; Chen, Sian-Cong; Huang, Tzu-Ping

    2014-05-01

    Infrared spectra and chemical reactions of acetylene diluted in solid nitrogen at 10 K upon irradiation with vacuum ultraviolet (VUV) light and energetic electrons were investigated in separate experiments. Irradiation of the matrix sample with VUV light peaking at 160 and 121.6 nm yielded simple products, including C2H, CN, and isomers of C2N2. In contrast, electron irradiation of a similar sample generated N3, C2H, and various nitriles. The reaction mechanisms for photolysis and radiolysis of the matrix samples are discussed. Our results may help explain the distribution of trace species detected in the atmosphere of Titan. In addition, the UV absorption spectrum of the electron-bombarded icy sample was obtained and might be useful for future spectral investigations of Pluto by New Horizons.

  12. Ultraviolet light curves of the dwarf novae U Geminorum and VW Hydri

    NASA Technical Reports Server (NTRS)

    Wu, C.-C.; Panek, R. J.

    1982-01-01

    The optical light curves of many dwarf novae show a prominent hump. This hump is attributed to a hot spot located where the gas stream from the cool secondary star strikes the accretion disk around the white dwarf primary. In the present investigation, the energy distribution of the hot spot is obtained from the amplitude of the hump in different wavelength regions. The color temperature of the hot spot is derived, and the temperature and optical thickness for thermal free-free emission models for the spot is discussed. The nature of the disk is studied by comparing its UV-optical energy distribution with computed accretion disk models. The ultraviolet light curves of two quiescent dwarf novae, U Gem and VW Hyi is derived by combining Astronomical Netherlands Satellite (ANS) photometry from several different epochs.

  13. Development of ellipsoidal focusing mirror for soft x-ray and extreme ultraviolet light

    NASA Astrophysics Data System (ADS)

    Mimura, Hidekazu; Takei, Yoshinori; Saito, Takahiro; Kume, Takehiro; Motoyama, Hiroto; Egawa, Satoru; Takeo, Yoko; Higashi, Takahiro

    2015-08-01

    Mirrors are key devices for creating various systems in optics. Focusing X-ray and extreme ultraviolet (EUV) light requires mirror surfaces with an extremely high accuracy. The figure of an ellipsoidal mirror is obtained by rotating an elliptical profile, and using such a mirror, soft X-ray and EUV light can be focused to dimensions on the order of nanometers without chromatic aberration. Although the theoretical performance of ellipsoidal mirrors is extremely high, the fabrication of an ideal ellipsoidal mirror remains problematic. Based on this background, we have been working to develop a fabrication system for ellipsoidal mirrors. In this proceeding, we briefly introduce the fabrication process and the soft X-ray focusing performance of the ellipsoidal mirror fabricated using the proposed process.

  14. Lighting considerations in controlled environments for nonphotosynthetic plant responses to blue and ultraviolet radiation

    NASA Technical Reports Server (NTRS)

    Caldwell, M. M.; Flint, S. D.

    1994-01-01

    This essay will consider both physical and photobiological aspects of controlled environment lighting in the spectral region beginning in the blue and taken to the normal limit of the solar spectrum in the ultraviolet. The primary emphasis is directed to questions of plant response to sunlight. Measurement and computations used in radiation dosimetry in this part of the spectrum are also briefly treated. Because of interest in the ozone depletion problem, there has been some activity in plant UV-B research and there are several recent reviews available. Some aspects of growth chamber lighting as it relates to UV-B research were covered earlier. Apart from work related to the blue/UV-A receptor, less attention has been given to UV-A responses.

  15. Grating-type mid-infrared light absorber based on silicon carbide material.

    PubMed

    Xue, Wenrui; Chen, Xi; Peng, Yanling; Yang, Rongcao

    2016-10-03

    A kind of grating-type mid-infrared light absorber based on silicon carbide (SiC) material is designed and its absorption properties are studied using the finite-difference frequency-domain (FDFD) method. The results show that, its absorption mechanism is the excitation of surface plasmon and magnetic polariton as well as the loss of materials. Due to the optical characteristics of the SiC material in the mid-infrared band and the truncated pyramid structure in the grating, in the range of 10.5-12.5μm and 0-80°, absorptivity of higher than 80% can be obtained with optimized structural parameters. Among six structural parameters, the layer number of the composite layers has a relatively great influence on the absorption properties, while the thickness of the dielectric layer has less influence on the absorption properties.

  16. Disturbance of light-absorbing aerosols on the albedo in a winter snowpack of Central Tibet.

    PubMed

    Ming, Jing; Wang, Pengling; Zhao, Shuyu; Chen, Pengfei

    2013-08-01

    A field observation on the albedo of the snowpack in Central Tibet was conducted in the Nam Co region in the winter of 2011. Snow properties, including grain size and density, were measured in the field, and surface-layer snow samples (down to 5 cm) were collected. The average concentrations of black carbon and dust were 72 ppbm (close to that in the glaciers of Mt. Nyainqentanglha) and 120 ppmm, respectively. Inverse trends were found to exist between the albedo of the snowpack and light-absorbing aerosols (LAAs) as well as grain size growth. Modeling showed that black carbon, dust, and grain growth in the winter snowpack can reduce the broadband albedo by 11%, 28%, and 61%, respectively.

  17. Radiative forcing by light absorbing impurities in snow from MODIS surface reflectance data

    NASA Astrophysics Data System (ADS)

    Painter, Thomas H.; Bryant, Ann C.; Skiles, S. McKenzie

    2012-09-01

    The episodic deposition of dust and carbonaceous particles to snow decreases snow surface albedo and enhances absorption of solar radiation, leading to accelerated snowmelt, negative glacier mass balance, and the snow-albedo feedback. Until now, no remote sensing retrieval has captured the spatial and temporal variability of this forcing. Here we present the MODIS Dust Radiative Forcing in Snow (MODDRFS) model that retrieves surface radiative forcing by light absorbing impurities in snow cover from Moderate Resolution Imaging Spectroradiometer (MODIS) surface reflectance data. Validation of MODDRFS with a 7-year record of in situ measurements indicates the radiative forcing retrieval has positive bias at lower values and slight negative bias above 200 W m-2, subject to mixed pixel uncertainties. With bias-correction, MODDRFS has a root mean squared error of 32 W m-2 and mean absolute error of 25 W m-2. We demonstrate MODDRFS in the Upper Colorado River Basin and Hindu Kush-Himalaya.

  18. Column-switching high-performance liquid chromatographic assay for determination of asiaticoside in rat plasma and bile with ultraviolet absorbance detection.

    PubMed

    Baek, M; Rho, Y S; Kim, D H

    1999-09-24

    A column-switching high-performance liquid chromatography (HPLC) method is described for the determination of asiaticoside in rat plasma and bile using column-switching and ultraviolet (UV) absorbance detection. Plasma was simply deproteinated with acetonitrile prior to injection and bile was directly injected onto the HPLC system consisting of a clean-up column, a concentrating column, and an analytical column, which were connected with two six-port switching valves. Detection of asiaticoside was accurate and repeatable, with a limit of quantification of 0.125 microg/ml in plasma and 1 microg/ml in bile. The calibration curves were linear in a concentration range of 0.125-2.5 microg/ml and 1-20 microg/ml for asiaticoside in rat plasma and bile, respectively. This method has been successfully applied to determine the level of asiaticoside in rat plasma and bile samples from pharmacokinetics and biliary excretion studies.

  19. Carrier Conduction and Light Emission by Modification of Poly(alkylfluorene) Interface under Vacuum Ultraviolet Light Irradiation

    NASA Astrophysics Data System (ADS)

    Ohmori, Yutaka; Kajii, Hirotake; Terashima, Daiki; Kusumoto, Yusuke

    2013-03-01

    Organic field effect transistors (OFETs) have been extensively studied for flexible electronics. The characteristics of poly(9,9-dioctylfluorenyl-2,7-dyl) (F8) modified by thermal or light are strongly dependent on the carrier transport and optical characteristics. We investigate all solution-processed OFETs with Ag nano-ink as gate electrodes patterned by Vacuum Ultraviolet (VUV) (172 nm). Bi-layer gate insulators of amorphous fluoro-polymer CYTOP (Asahi Glass Corp.) and poly(methylmethacrylate) (PMMA) were used. Top-gate-type OFETs with ITO source/drain electrode utilizing F8 or poly(9,9-dioctylfluorene-co-benzothiadiazole) (F8BT) as an active layer were fabricated, and investigated the carrier conduction and emission characteristic. Without VUV irradiation, both OFETs showed the ambipolar and light-emitting characteristics. On the other hand, F8 devices with VUV exhibited only p-type conduction. The quenching centers were generated in F8 layer by VUV irradiation, which are related to the electron trap sites at the interface. OFETs with F8BT showed both p- and n-type conduction even after VUV. F8BT suffers less damage by VUV and maintain light emission. Light emitting transistors were realized utilizing F8BT patterned by VUV irradiation. This research was partially supported financially by MEXT. The authors thank Harima Chemicals Inc. for providing Ag nano-ink.

  20. Evaluation of specific ultraviolet absorbance as an indicator of the chemical composition and reactivity of dissolved organic carbon

    USGS Publications Warehouse

    Weishaar, J.L.; Aiken, G.R.; Bergamaschi, B.A.; Fram, M.S.; Fujii, R.; Mopper, K.

    2003-01-01

    Specific UV absorbance (SUVA) is defined as the UV absorbance of a water sample at a given wavelength normalized for dissolved organic carbon (DOC) concentration. Our data indicate that SUVA, determined at 254 nm, is strongly correlated with percent aromaticity as determined by 13C NMR for 13 organic matter isolates obtained from a variety of aquatic environments. SUVA, therefore, is shown to be a useful parameter for estimating the dissolved aromatic carbon content in aquatic systems. Experiments involving the reactivity of DOC with chlorine and tetramethylammonium hydroxide (TMAH), however, show a wide range of reactivity for samples with similar SUVA values. These results indicate that, while SUVA measurements are good predictors of general chemical characteristics of DOC, they do not provide information about reactivity of DOC derived from different types of source materials. Sample pH, nitrate, and iron were found to influence SUVA measurements.

  1. Changes in ultraviolet absorbance and hence in protective efficacy against lipid peroxidation of organic sunscreens after UVA irradiation.

    PubMed

    Damiani, Elisabetta; Rosati, Luca; Castagna, Riccardo; Carloni, Patricia; Greci, Lucedio

    2006-03-01

    Owing to the spectral distribution of solar UV, the UVA component of sunlight is now believed to be the main cause of photoaging and photocarcinogenesis and is much more effective than UVB in inducing peroxidative damage. Consequently, most skin care cosmetic products now include UVA filters in their formulations along with UVB filters. These modern sunscreens should provide and maintain their initial absorbance, hence protection, throughout the entire period of exposure to sunlight. However, not all UVA and UVB filters are sufficiently photostable. In this study, we examine the correlation between the photochemical degradation of sunscreen agents under UVA irradiation, with particular reference to the UVA-absorber 4-tert-butyl-4'-methoxydibenzoylmethane, alone and in combination with other organic UV filters (2-ethylhexyl 4 methoxycinnamate and 2-ethylhexyl 2-cyano-3,3-diphenylacrylate) and their ability to prevent UVA-induced lipid peroxidation. Since antioxidants are also added to formulations to deactivate free radicals generated during UVA exposure, vitamin E and the synthetic antioxidant, bis(2,2,6,6-tetramethyl-1-oxyl-piperidine-4-yl)sebacate, a nitroxide derivative, were also included in this study. By using simple in vitro tests, the results show that a decrease in spectral absorbance of the UV filters correlates in most cases with increased UVA-induced lipid peroxidation; this depends on the specific UV absorber analysed and also on whether they are alone or in combination. Furthermore, the combined presence or absence of antioxidants has a profound effect on this oxidative event. In particular, the nitroxide appears to be a more efficient photo-antioxidant than vitamin E. Similar experiments were also performed under natural sunlight and the results obtained did not differ substantially from those performed under UVA. The results presented and discussed in this work may help in understanding the effects of UVA/UVB absorbers and antioxidants upon the

  2. A Photochromic Histidine Kinase Rhodopsin (HKR1) That Is Bimodally Switched by Ultraviolet and Blue Light*

    PubMed Central

    Luck, Meike; Mathes, Tilo; Bruun, Sara; Fudim, Roman; Hagedorn, Rolf; Tran Nguyen, Tra My; Kateriya, Suneel; Kennis, John T. M.; Hildebrandt, Peter; Hegemann, Peter

    2012-01-01

    Rhodopsins are light-activated chromoproteins that mediate signaling processes via transducer proteins or promote active or passive ion transport as ion pumps or directly light-activated channels. Here, we provide spectroscopic characterization of a rhodopsin from the Chlamydomonas eyespot. It belongs to a recently discovered but so far uncharacterized family of histidine kinase rhodopsins (HKRs). These are modular proteins consisting of rhodopsin, a histidine kinase, a response regulator, and in some cases an effector domain such as an adenylyl or guanylyl cyclase, all encoded in a single protein as a two-component system. The recombinant rhodopsin fragment, Rh, of HKR1 is a UVA receptor (λmax = 380 nm) that is photoconverted by UV light into a stable blue light-absorbing meta state Rh-Bl (λmax = 490 nm). Rh-Bl is converted back to Rh-UV by blue light. Raman spectroscopy revealed that the Rh-UV chromophore is in an unusual 13-cis,15-anti configuration, which explains why the chromophore is deprotonated. The excited state lifetime of Rh-UV is exceptionally stable, probably caused by a relatively unpolar retinal binding pocket, converting into the photoproduct within about 100 ps, whereas the blue form reacts 100 times faster. We propose that the photochromic HKR1 plays a role in the adaptation of behavioral responses in the presence of UVA light. PMID:23027869

  3. A novel screen design for anti-ambient light front projection display with angle-selective absorber

    NASA Astrophysics Data System (ADS)

    Liao, Tianju; Chen, Weigang; He, Kebo; Zhang, Zhaoyu

    2016-03-01

    Ambient light is destructive to the reflective type projection system's contrast ratio which has great influence on the image quality. In contrast to the conventional front projection, short-throw projection has its advantage to reject the ambient light. Fresnel lens-shaped reflection layer is adapted to direct light from a large angle due to the low lens throw ratio to the viewing area. The structure separates the path of the ambient light and projection light, creating the chance to solve the problem that ambient light is mixed with projection light. However, with solely the lens-shaped reflection layer is not good enough to improve the contrast ratio due to the scattering layer, which contributes a necessarily wide viewing angle, could interfere with both light paths before hitting the layer. So we propose a new design that sets the draft angle surface with absorption layer and adds an angle-selective absorber to separate these two kinds of light. The absorber is designed to fit the direction of the projection light, leading to a small absorption cross section for the projection light and respectfully big absorption cross section for the ambient light. We have calculated the design with Tracepro, a ray tracing program and find a nearly 8 times contrast ratio improvement against the current design in theory. This design can hopefully provide efficient display in bright lit situation with better viewer satisfaction.

  4. ACTUAL-WASTE TESTING OF ULTRAVIOLET LIGHT TO AUGMENT THE ENHANCED CHEMICAL CLEANING OF SRS SLUDGE

    SciTech Connect

    Martino, C.; King, W.; Ketusky, E.

    2012-07-10

    In support of Savannah River Site (SRS) tank closure efforts, the Savannah River National Laboratory (SRNL) conducted Real Waste Testing (RWT) to evaluate Enhanced Chemical Cleaning (ECC), an alternative to the baseline 8 wt% oxalic acid (OA) chemical cleaning technology for tank sludge heel removal. ECC utilizes a more dilute OA solution (2 wt%) and an oxalate destruction technology using ozonolysis with or without the application of ultraviolet (UV) light. SRNL conducted tests of the ECC process using actual SRS waste material from Tanks 5F and 12H. The previous phase of testing involved testing of all phases of the ECC process (sludge dissolution, OA decomposition, product evaporation, and deposition tank storage) but did not involve the use of UV light in OA decomposition. The new phase of testing documented in this report focused on the use of UV light to assist OA decomposition, but involved only the OA decomposition and deposition tank portions of the process. Compared with the previous testing at analogous conditions without UV light, OA decomposition with the use of UV light generally reduced time required to reach the target of <100 mg/L oxalate. This effect was the most pronounced during the initial part of the decomposition batches, when pH was <4. For the later stages of each OA decomposition batch, the increase in OA decomposition rate with use of the UV light appeared to be minimal. Testing of the deposition tank storage of the ECC product resulted in analogous soluble concentrations regardless of the use or non-use of UV light in the ECC reactor.

  5. Identification of a Natural Green Light Absorbing Chloride Conducting Channelrhodopsin from Proteomonas sulcata*

    PubMed Central

    Wietek, Jonas; Broser, Matthias; Krause, Benjamin S.; Hegemann, Peter

    2016-01-01

    Chloride conducting channelrhodopsins (ChloCs) are new members of the optogenetic toolbox that enable neuronal inhibition in target cells. Originally, ChloCs have been engineered from cation conducting channelrhodopsins (ChRs), and later identified in a cryptophyte alga genome. We noticed that the sequence of a previously described Proteomonas sulcata ChR (PsChR1) was highly homologous to the naturally occurring and previously reported ChloCs GtACR1/2, but was not recognized as an anion conducting channel. Based on electrophysiological measurements obtained under various ionic conditions, we concluded that the PsChR1 photocurrent at physiological conditions is strongly inward rectifying and predominantly carried by chloride. The maximum activation was noted at excitation with light of 540 nm. An initial spectroscopic characterization of purified protein revealed that the photocycle and the transport mechanism of PsChR1 differ significantly from cation conducting ChRs. Hence, we concluded that PsChR1 is an anion conducting ChR, now renamed PsACR1, with a red-shifted absorption suited for multicolor optogenetic experiments in combination with blue light absorbing cation conducting ChRs. PMID:26740624

  6. Monte Carlo simulation of reflection spectra of random multilayer media strongly scattering and absorbing light

    SciTech Connect

    Meglinskii, I V

    2001-12-31

    The reflection spectra of a multilayer random medium - the human skin - strongly scattering and absorbing light are numerically simulated. The propagation of light in the medium and the absorption spectra are simulated by the stochastic Monte Carlo method, which combines schemes for calculations of real photon trajectories and the statistical weight method. The model takes into account the inhomogeneous spatial distribution of blood vessels, water, and melanin, the degree of blood oxygenation, and the hematocrit index. The attenuation of the incident radiation caused by reflection and refraction at Fresnel boundaries of layers inside the medium is also considered. The simulated reflection spectra are compared with the experimental reflection spectra of the human skin. It is shown that a set of parameters that was used to describe the optical properties of skin layers and their possible variations, despite being far from complete, is nevertheless sufficient for the simulation of the reflection spectra of the human skin and their quantitative analysis. (laser applications and other topics in quantum electronics)

  7. Identification of a Natural Green Light Absorbing Chloride Conducting Channelrhodopsin from Proteomonas sulcata.

    PubMed

    Wietek, Jonas; Broser, Matthias; Krause, Benjamin S; Hegemann, Peter

    2016-02-19

    Chloride conducting channelrhodopsins (ChloCs) are new members of the optogenetic toolbox that enable neuronal inhibition in target cells. Originally, ChloCs have been engineered from cation conducting channelrhodopsins (ChRs), and later identified in a cryptophyte alga genome. We noticed that the sequence of a previously described Proteomonas sulcata ChR (PsChR1) was highly homologous to the naturally occurring and previously reported ChloCs GtACR1/2, but was not recognized as an anion conducting channel. Based on electrophysiological measurements obtained under various ionic conditions, we concluded that the PsChR1 photocurrent at physiological conditions is strongly inward rectifying and predominantly carried by chloride. The maximum activation was noted at excitation with light of 540 nm. An initial spectroscopic characterization of purified protein revealed that the photocycle and the transport mechanism of PsChR1 differ significantly from cation conducting ChRs. Hence, we concluded that PsChR1 is an anion conducting ChR, now renamed PsACR1, with a red-shifted absorption suited for multicolor optogenetic experiments in combination with blue light absorbing cation conducting ChRs.

  8. Co/graphite based light weight microwave absorber for electromagnetic shielding and stealth applications

    NASA Astrophysics Data System (ADS)

    Ansari, Azizurrahaman; Jaleel Akhtar, Mohammad

    2017-01-01

    The magnetic, thermal, thermo-mechanical, electromagnetic and microwave absorption properties of Co/graphite loaded polystyrene composites prepared by melt blending and injection molding techniques are studied in X-band (8.4–12.4 GHz) for seeking their usage as efficient light weight microwave absorbers. For profound understanding of electromagnetic absorption process at micro level, the advanced SEM and x-ray diffraction testing of the composites are carried out. The magnetic properties of the prepared Co/graphite loaded polystyrene composites are studied using the vibrating sample magnetometer. The thermal stability and thermo-mechanical properties of the prepared composites are analyzed by thermo gravimetric analysis and dynamic mechanical and thermal analysis, respectively. The complex permittivity and permeability values of the prepared composite samples in X-band of microwave frequency are extracted from the scattering data recorded during the vector network analyzer measurements. The minimum reflection loss (maximum absorption loss) of  ‑32.02 dB (99.94%) is achieved at 10.13 GHz for Co/graphite loaded polystyrene composite with the excess loading of graphite flakes for sample thickness of 1.8 mm. High absorption loss, light weight and low thickness of the proposed multicomponent Co/graphite loaded polystyrene composites make them promising candidates for electromagnetic shielding and stealth applications.

  9. [Inactivation of EV71 by Exposure to Heat and Ultraviolet Light].

    PubMed

    Xie, Jing; Li, Dandi; Xie, Guangcheng; Hu, Yaqian; Zhang, Qing; Kong, Xiangyu; Guo, Nijun; Li, Yuning; Duan, Zhaojun

    2015-09-01

    Enterovirus 71 (EV71) is a major agent of hand, foot and mouth disease that can cause a severe burden of disease to children. To identify an effective method for the control and prevention of EV71, we studied the effect of exposure to heat and ultraviolet (UV) light upon EV71 inactivation. We found that exposure to 50 degrees C could not inactivate the infectivity of EV71. However, exposure to 60 degrees C and 70 degrees C could inactivate EV71 effectively. EV71 could be inactivated after exposure to UV light at a distance between the sample and a lamp of 30 cm for 30 min or 60 min because viral genomic RNA was destroyed. However, fetal bovine serum (FBS) could attenuate the inactivation proffered by heat and UV light. Attenuation effects of FBS were correlated positively with FBS concentration. Hence, EV71 can be inactivated by exposure to heat and UV light, and our results could provide guidance on prevention of the spread of EV71.

  10. High-Power Genuine Ultraviolet Light-Emitting Diodes Based On Colloidal Nanocrystal Quantum Dots.

    PubMed

    Kwak, Jeonghun; Lim, Jaehoon; Park, Myeongjin; Lee, Seonghoon; Char, Kookheon; Lee, Changhee

    2015-06-10

    Thin-film ultraviolet (UV) light-emitting diodes (LEDs) with emission wavelengths below 400 nm are emerging as promising light sources for various purposes, from our daily lives to industrial applications. However, current thin-film UV-emitting devices radiate not only UV light but also visible light. Here, we introduce genuine UV-emitting colloidal nanocrystal quantum dot (NQD) LEDs (QLEDs) using precisely controlled NQDs consisting of a 2.5-nm-sized CdZnS ternary core and a ZnS shell. The effective core size is further reduced during the shell growth via the atomic diffusion of interior Cd atoms to the exterior ZnS shell, compensating for the photoluminescence red shift. This design enables us to develop CdZnS@ZnS UV QLEDs with pure UV emission and minimal parasitic peaks. The irradiance is as high as 2.0-13.9 mW cm(-2) at the peak wavelengths of 377-390 nm, several orders of magnitude higher than that of other thin-film UV LEDs.

  11. Involvement of active oxygen in lipid peroxide radical reaction of epidermal homogenate following ultraviolet light exposure

    SciTech Connect

    Nishi, J.; Ogura, R.; Sugiyama, M.; Hidaka, T.; Kohno, M. )

    1991-07-01

    To elucidate the radical mechanism of lipid peroxidation induced by ultraviolet light (UV) irradiation, an electron spin resonance (ESR) study was made on epidermal homogenate prepared from albino rat skin. The exposure of the homogenate to UV light resulted in an increase in lipid peroxide content, which was proportional to the time of UV exposure. Using ESR spin trapping (dimethyl-1-pyrroline-N-oxide, DMPO), the DMPO spin adduct spectrum of lipid radicals (L.) was measured following UV exposure (DMPO-L.:aN = 15.5 G, aH = 22.7 G), as was the spectrum of DMPO-hydroxyl radical (DMPO-OH, aN = aH = 15.5 G). In the presence of superoxide dismutase, the DMPO spin adduct spectrum of lipid radicals was found to be reduced remarkably. Therefore, it was shown that the generation of the lipid radicals partially involves superoxide anion radicals, in addition to hydroxyl radicals. In the ESR free-radical experiment, an ESR signal appeared at g = 2.0064 when the ESR tube filled with homogenate was exposed to UV light at -150 degrees C. The temperature-dependent change in the ESR free radical signal of homogenate exposed to UV light was observed at temperatures varying from -150 degrees C to room temperature. By using degassed samples, it was confirmed that oxygen is involved in the formation of the lipid peroxide radicals (LOO.) from the lipid radicals (L.).

  12. Effect of ultraviolet light exposure to boron doped hydrogenated amorphous silicon oxide thin film

    NASA Astrophysics Data System (ADS)

    Baek, Seungsin; Iftiquar, S. M.; Jang, Juyeon; Lee, Sunhwa; Kim, Minbum; Jung, Junhee; Park, Hyeongsik; Park, Jinjoo; Kim, Youngkuk; Shin, Chonghoon; Lee, Youn-Jung; Yi, Junsin

    2012-11-01

    We have investigated the effect of ultraviolet (UV) light exposure to boron doped (p-type) hydrogenated amorphous silicon oxide (p-a-SiO:H) thin semiconductor films by measuring changes in its structural, electrical and optical properties. After a 50 h of UV light soaking (LS) of the films, that have 1.2, 6.9, 15.2, 25.3 at.% oxygen content (C(O)) and optical gap (E04) of 1.897, 2.080, 2.146 and 2.033 eV, show a relative increase in the C(O) by 28.0%, 9.8%, 2.0%, 3.1%, a relative increase in the Urbach energy (Eu) by 42%, 24%, 8%, 0%, decrease in the E04 by 66, 2, 12, 19 meV and the gap state defect density (Nd) show an increase by 6.5%, 3.4%, 0.7%, 0.1%. At higher oxygen content the observed UV light induced degradation (LID) is relatively less than that for films with lower oxygen content, indicating that higher oxides face less changes under the UV light.

  13. Influence of ultraviolet light in the toxicity of sediments contaminated with polycyclic aromatic hydrocarbons

    SciTech Connect

    Ankley, G.T.; Monson, P.D.; Kosian, P.A.; Collyard, S.A.

    1994-12-31

    Standard 10-d toxicity tests were conducted with freshwater benthic invertebrates using sediments containing a range of concentrations of polycyclic aromatic hydrocarbons (PAHs). The assays were performed both under normal laboratory fluorescent light and ultraviolet (UV) light which mimicked wavelengths present in sunlight at about 10% of ambient solar intensity. Additionally, field experiments used an in situ apparatus to evaluate the phototoxic response of the aquatic oligochaete Lumbriculus variegatus to sediments contaminated with PAHs. Those experiments were conducted using both sunlight exposed and shaded test chambers. In addition to a PAH contaminated site, a reference site lacking in PAHs also was tested as a control. Laboratory tests conducted with PAH contaminated sediments exposed to UV light resulted in significantly greater mortality of Hyalella azteca and Lumbriculus variegatus than tests performed under otherwise comparable conditions with fluorescent light. Results from field experiments corroborated this trend. The results suggest that failure to consider photoactivation of PAHs by sunlight could result in sediment toxicity test methods or criteria which are underprotective of benthic organisms.

  14. Application of ultraviolet light-emitting diodes (UV-LEDs) for water disinfection: A review.

    PubMed

    Song, Kai; Mohseni, Madjid; Taghipour, Fariborz

    2016-05-01

    Ultraviolet (UV) disinfection is an effective technology for the inactivation of pathogens in water and is of growing interest for industrial application. A new UV source - ultraviolet light-emitting diode (UV-LED) - has emerged in the past decade with a number of advantages compared to traditional UV mercury lamps. This promising alternative raises great interest in the research on application of UV-LEDs for water treatment. Studies on UV-LED water disinfection have increased during the past few years. This article presents a comprehensive review of recent studies on UV-LEDs with various wavelengths for the inactivation of different microorganisms. Many inconsistent and incomparable data were found from published studies, which underscores the importance of establishing a standard protocol for studying UV-LED inactivation of microorganisms. Different UV sensitivities to UV-LEDs and traditional UV lamps were observed in the literature for some microorganisms, which requires further investigation for a better understanding of microorganism response to UV-LEDs. The unique aspects of UV-LEDs improve inactivation effectiveness by applying LED special features, such as multiple wavelengths and pulsed illumination; however, more studies are needed to investigate the influencing factors and mechanisms. The special features of UV-LEDs offer the flexibility of novel reactor designs for a broad application of UV-LED reactors.

  15. Defect-Enabled Electrical Current Leakage in Ultraviolet Light-Emitting Diodes

    DOE PAGES

    Moseley, Michael William; Allerman, Andrew A.; Crawford, Mary H.; ...

    2015-04-13

    The AlGaN materials system offers a tunable, ultra-wide bandgap that is exceptionally useful for high-power electronics and deep ultraviolet optoelectronics. Moseley et al. (pp. 723–726) investigate a structural defect known as an open-core threading dislocation or ''nanopipe'' that is particularly detrimental to devices that employ these materials. Furthermore, an AlGaN thin film was synthesized using metal-organic chemical-vapor deposition. Electrical current leakage is detected at a discrete point using a conductive atomic-force microscope (CAFM). However, no physical feature or abnormality at this location was visible by an optical microscope. The AlGaN thin film was then etched in hot phosphoric acid, andmore » the same location that was previously analyzed was revisited with the CAFM. The point that previously exhibited electrical current leakage had been decorated with a 1.1 μm wide hexagonal pit, which identified the site of electrical current leakage as a nanopipe and allows these defects to be easily observed by optical microscopy. Moreover, with this nanopipe identification and quantification strategy, the authors were able to correlate decreasing ultraviolet light-emitting diode optical output power with increasing nanopipe density.« less

  16. Defect-Enabled Electrical Current Leakage in Ultraviolet Light-Emitting Diodes

    SciTech Connect

    Moseley, Michael William; Allerman, Andrew A.; Crawford, Mary H.; Wierer, Jonathan; Smith, Michael L.; Biedermann, Laura

    2015-04-13

    The AlGaN materials system offers a tunable, ultra-wide bandgap that is exceptionally useful for high-power electronics and deep ultraviolet optoelectronics. Moseley et al. (pp. 723–726) investigate a structural defect known as an open-core threading dislocation or ''nanopipe'' that is particularly detrimental to devices that employ these materials. Furthermore, an AlGaN thin film was synthesized using metal-organic chemical-vapor deposition. Electrical current leakage is detected at a discrete point using a conductive atomic-force microscope (CAFM). However, no physical feature or abnormality at this location was visible by an optical microscope. The AlGaN thin film was then etched in hot phosphoric acid, and the same location that was previously analyzed was revisited with the CAFM. The point that previously exhibited electrical current leakage had been decorated with a 1.1 μm wide hexagonal pit, which identified the site of electrical current leakage as a nanopipe and allows these defects to be easily observed by optical microscopy. Moreover, with this nanopipe identification and quantification strategy, the authors were able to correlate decreasing ultraviolet light-emitting diode optical output power with increasing nanopipe density.

  17. THE FIRST STRAY LIGHT CORRECTED EXTREME-ULTRAVIOLET IMAGES OF SOLAR CORONAL HOLES

    SciTech Connect

    Shearer, Paul; Gilbert, Anna C.; Frazin, Richard A.; Hero III, Alfred O. E-mail: annacg@umich.edu E-mail: hero@umich.edu

    2012-04-10

    Coronal holes are the source regions of the fast solar wind, which fills most of the solar system volume near the cycle minimum. Removing stray light from extreme-ultraviolet (EUV) images of the Sun's corona is of high astrophysical importance, as it is required to make meaningful determinations of temperatures and densities of coronal holes. EUV images tend to be dominated by the component of the stray light due to the long-range scatter caused by the microroughness of telescope mirror surfaces, and this component has proven very difficult to measure in pre-flight characterization. In-flight characterization heretofore has proven elusive due to the fact that the detected image is simultaneously nonlinear in two unknown functions: the stray light pattern and the true image that would be seen by an ideal telescope. Using a constrained blind deconvolution technique that takes advantage of known zeros in the true image provided by a fortuitous lunar transit, we have removed the stray light from solar images seen by the EUVI instrument on STEREO-B in all four filter bands (171, 195, 284, and 304 A). Uncertainty measures of the stray light corrected images, which include the systematic error due to misestimation of the scatter, are provided. It is shown that in EUVI, stray light contributes up to 70% of the emission in coronal holes seen on the solar disk, which has dramatic consequences for diagnostics of temperature and density and therefore estimates of key plasma parameters such as the plasma {beta} and ion-electron collision rates.

  18. Effects of exposure to physical factors on homeopathic preparations as determined by ultraviolet light spectroscopy.

    PubMed

    Marschollek, Barbara; Nelle, Mathias; Wolf, Martin; Baumgartner, Stephan; Heusser, Peter; Wolf, Ursula

    2010-01-08

    Clinical trials have reported statistically significant and clinically relevant effects of homeopathic preparations. We applied ultraviolet (UV) spectroscopy to investigate the physical properties of homeopathic preparations and to contribute to an understanding of the not-yet-identified mode of action. In previous investigations, homeopathic preparations had significantly lower UV light transmissions than controls. The aim of this study was to explore the possible effects of external factors (UV light and temperature) on the homeopathic preparations. Homeopathic centesimal (c) dilutions, 1c to 30c, of copper sulfate (CuSO(4)), decimal dilutions of sulfur (S(8)), 1x to 30x, and controls (succussed potentization medium) were prepared, randomized, and blinded. UV transmission was measured at six different time points after preparation (from 4 to 256 days). In addition, one series of samples was exposed to UV light of a sterilization lamp for 12 h, one was incubated at 37 degrees Celsius for 24 h, and one was heated to 90 degrees Celsius for 15 min. UV light transmission values from 190 or 220 nm to 340 nm were measured several times and averaged. After each exposure, UV transmission of the homeopathic preparations of CuSO(4) was significantly reduced compared to the controls, particularly after heating to 37 degrees Celsius. Overall, the nonexposed CuSO(4) preparations did not show significantly lower UV transmission compared to controls; however, the pooled subgroup of measurements at days 26, 33, and 110 yielded significant differences. UV light transmission for S(8) preparations did not show any differences compared to controls. Our conclusion is that exposure to external factors, incubation at 37 degrees Celsius in particular, increases the difference in light transmission of homeopathic CuSO(4) preparations compared to controls.

  19. 2004: Finite-Difference Time Domain Solution of Light Scattering by an Infinite Dielectric Column Immersed in an Absorbing Medium

    NASA Technical Reports Server (NTRS)

    Sun, W.; Loeb, N. G.; Tanev, S.; Videen, G.

    2004-01-01

    The two-dimensional (2-D) finite-difference time domain (FDTD) method is applied to calculate light scattering and absorption by an arbitrarily shaped infinite column embedded in an absorbing dielectric medium. A uniaxial perfectly matched layer (UPML) absorbing boundary condition (ABC) is used to truncate the computational domain. The single-scattering properties of the infinite column embedded in the absorbing medium, including scattering phase functions, extinction and absorption efficiencies, are derived using an area integration of the internal field. An exact solution for light scattering and absorption by a circular cylinder in an absorbing medium is used to examine the accuracy of the 2-D UPML FDTD code. With use of a cell size of 1/120 incident wavelength in the FDTD calculations, the errors in the extinction and absorption efficiencies and asymmetry factors from the 2-D UPML FDTD are generally smaller than approx .1%. The errors in the scattering phase functions are typically smaller than approx .4%. Using the 2-D UPML FDTD technique, light scattering and absorption by long noncircular columns embedded in absorbing media can be accurately solved.

  20. The light-induced carotenoid absorbance changes in Rhodopseudomonas sphaeroides: an analysis and interpretation of the band shifts.

    PubMed

    Symons, M; Swysen, C; Sybesma, C

    1977-12-23

    An analysis has been made of the spectrum of the carotenoid absorption band shift generated by continuous illumination of chromatophores of the GlC-mutant of Rhodopseudomonas sphaeroides at room temperature by means of three computer programs. There appears to be at least two pools of the same carotenoid, only one of which, comprising about 20% of the total carotenoid content, is responsible for the light-induced absorbance changes. The 'remaining' pool absorbs at wavelengths which were about 5 nm lower than those at which the 'changing' pool absorbs. This difference in absorption wavelength could indicate that the two pools are influenced differently by permanent local electric fields. The electrochromic origin of the absorbance changes has been demonstrated directly; the isosbestic points of the absorption difference spectrum move to shorter wavelengths upon lowering of the light-induced electric field. Band shifts up to 1.7 nm were observed. A comparison of the light-induced absorbance changes with a KCl-valinomycin-induced diffusion potential has been used to calibrate the electrochromic shifts. The calibration value appeared to be 137 +/- 6 mV per nm shift.

  1. Ultraviolet-C light effect on physicochemical, bioactive, microbiological, and sensorial characteristics of carrot (Daucus carota) beverages.

    PubMed

    Hernández-Carranza, Paola; Ruiz-López, Irving Israel; Pacheco-Aguirre, Francisco Manuel; Guerrero-Beltrán, José Ángel; Ávila-Sosa, Raúl; Ochoa-Velasco, Carlos Enrique

    2016-09-01

    The aim of this research was to evaluate the effect of ultraviolet-C light on physicochemical, bioactive, microbial, and sensory characteristics of carrot beverages. Beverages were formulated with different concentrations of carrot juice (60, 80, and 100% [v/v]) and treated with ultraviolet-C light at different flow rates (0, 0.5, 3.9, and 7.9 mL s(-1)) and times (5, 10, 15, 20, and 30 min), equivalent to ultraviolet-C dosages of 13.2, 26.4, 39.6, 52.8, and 79.2 J cm(-2) Total soluble solids, pH, and titratable acidity were not affected by the ultraviolet-C light treatment. Ultraviolet-C light significantly affected (p < 0.05) color parameters of pure juice; however, at low concentration of juice, total color change was slightly affected (ΔE = 2.0 ± 0.7). Phenolic compounds (4.1 ± 0.1, 5.2 ± 0.2, and 8.6 ± 0.3 mg of GAE 100 mL(-1) of beverage with 60, 80, and 100% of juice, respectively) and antioxidant capacity (6.1 ± 0.4, 8.5 ± 0.4, and 9.4 ± 0.3 mg of Trolox 100 mL(-1) of beverage with 60, 80, and 100% of juice, respectively) of carrot beverages were not affected by ultraviolet-C light treatment. Microbial kinetics showed that mesophiles were mostly reduced at high flow rates in carrot beverages with 60% of juice. Maximum logarithmic reductions for mesophiles and total coliforms were 3.2 ± 0.1 and 2.6 ± 0.1, respectively, after 30 min of ultraviolet-C light processing. Beverages were well accepted (6-7) by judges who did not perceive the difference between untreated and Ultraviolet-C light treated beverages.

  2. Submicron-resolution photoacoustic microscopy of endogenous light-absorbing biomolecules

    NASA Astrophysics Data System (ADS)

    Zhang, Chi

    Photoacoustic imaging in biomedicine has the unique advantage of probing endogenous light absorbers at various length scales with a 100% relative sensitivity. Among the several modalities of photoacoustic imaging, optical-resolution photoacoustic microscopy (OR-PAM) can achieve high spatial resolution, on the order of optical wavelength, at <1 mm depth in biological tissue (the optical ballistic regime). OR-PAM has been applied successfully to structural and functional imaging of blood vasculature and red blood cells in vivo. Any molecules which absorb sufficient light at certain wavelengths can potentially be imaged by PAM. Compared with pure optical imaging, which typically targets fluorescent markers, label-free PAM avoids the major concerns that the fluorescent labeling probes may disturb the function of biomolecules and may have an insufficient density. This dissertation aims to advance label-free OR-PAM to the subcellular scale. The first part of this dissertation describes the technological advancement of PAM yielding high spatial resolution in 3D. The lateral resolution was improved by using optical objectives with high numerical apertures for optical focusing. The axial resolution was improved by using broadband ultrasonic transducers for ultrasound detection. We achieved 220 nm lateral resolution in transmission mode, 0.43 microm lateral resolution in reflection mode, 7.6 microm axial resolution in normal tissue, and 5.8 microm axial resolution with silicone oil immersion/injection. The achieved lateral resolution and axial resolution were the finest reported at the time. With high-resolution in 3D, PAM was demonstrated to resolve cellular and subcellular structures in vivo, such as red blood cells and melanosomes in melanoma cells. Compared with previous PAM systems, our high-resolution PAM could resolve capillaries in mouse ears more clearly. As an example application, we demonstrated intracellular temperature imaging, assisted by fluorescence signal

  3. Crystal structure of the nucleosome containing ultraviolet light-induced cyclobutane pyrimidine dimer.

    PubMed

    Horikoshi, Naoki; Tachiwana, Hiroaki; Kagawa, Wataru; Osakabe, Akihisa; Matsumoto, Syota; Iwai, Shigenori; Sugasawa, Kaoru; Kurumizaka, Hitoshi

    2016-02-26

    The cyclobutane pyrimidine dimer (CPD) is induced in genomic DNA by ultraviolet (UV) light. In mammals, this photolesion is primarily induced within nucleosomal DNA, and repaired exclusively by the nucleotide excision repair (NER) pathway. However, the mechanism by which the CPD is accommodated within the nucleosome has remained unknown. We now report the crystal structure of a nucleosome containing CPDs. In the nucleosome, the CPD induces only limited local backbone distortion, and the affected bases are accommodated within the duplex. Interestingly, one of the affected thymine bases is located within 3.0 Å from the undamaged complementary adenine base, suggesting the formation of complementary hydrogen bonds in the nucleosome. We also found that UV-DDB, which binds the CPD at the initial stage of the NER pathway, also efficiently binds to the nucleosomal CPD. These results provide important structural and biochemical information for understanding how the CPD is accommodated and recognized in chromatin.

  4. Chromatin structure implicated in activation of HIV-1 gene expression by ultraviolet light

    SciTech Connect

    Valerie, K.; Rosenberg, M. )

    1990-08-01

    We have investigated the effects of different DNA-damaging agents on HIV-1 gene expression. We find that agents that produce bulky DNA lesions, similar to those induced by ultraviolet light (UV), all dramatically increase HIV-1 gene expression, whereas agents that produce primarily base damage and DNA breakage, such as ionizing radiation, have little or no effect. We show that these effects are independent of DNA synthesis per se and do not require DNA nucleotide excision repair. The drug novobiocin effectively prevents the UV activation process, consistent with the idea that a change in DNA chromatin structure may be required. We suggest that a transient decondensation of chromatin structure, an early step in DNA nucleotide excision repair but not in base excision repair, may be the triggering mechanism. The decondensation may allow the transcriptional machinery better access to the HIV-1 promoter region, thereby increasing gene expression.

  5. White Light Coronograph (WLC) and Ultra-Violet Coronal Spectrometer (UVCS)

    NASA Technical Reports Server (NTRS)

    Moore, R. L.

    1985-01-01

    The white light coronagraph (WLC) and ultraviolet coronal spectrometer (UVCS) together reveal the corona and the roots of the solar wind from 1.5 to 6 solar radii from Sun center. The WLC measures the plasma density and spatial structure of the corona and coronal mass ejections at a resolution of about 20 arcseconds. The UVCS, in combination with the WLC, measures the temperature and radial outflow speed of the coronal plasma. These instruments will detect mass ejections from active regions and high speed solar wind streams from coronal holes a few days before the source regions rotate onto the face of the Sun, thus giving a week or more of advanced warning for disturbed geomagnetic conditions at Earth.

  6. Curing BiVO4 Photoanodes with Ultraviolet Light Enhances Photoelectrocatalysis.

    PubMed

    Li, Tengfei; He, Jingfu; Peña, Bruno; Berlinguette, Curtis P

    2016-01-26

    Exposure of BiVO4 photoanodes to ultraviolet (UV) radiation for extended time periods (e.g., 20 h) produces a morphological change and concomitant improvement in photo-electrocatalytic (PEC) efficiency for driving water splitting directly by sunlight. The ∼230 mV cathodic shift in onset potential and doubling of the photocurrent at 1.23 V vs. RHE after UV curing are comparable to the effects engendered by the presence of a secondary catalyst layer. PEC measurements and absorption spectra indicate that the cathodic shift after UV curing corresponds to a suppression of charge recombination and a greater photovoltage generation caused by the shift of the flat-band potential, and not an improvement in electrocatalytic activity or light absorption. Spectroscopic surface analysis suggests that surface defect sites, which are eliminated by UV curing, for the differences in observed charge recombination.

  7. Psoralen plus near-ultraviolet light: a possible new method for measuring DNA repair synthesis

    SciTech Connect

    Heimer, Y.M.; Kol, R.; Shiloh, Y.; Riklis, E.

    1983-09-01

    A new method is proposed to inhibit semiconservative DNA synthesis in cultured cells while DNA repair synthesis is being measured. The cells are treated with the DNA-crosslinking agent Trioxalen (4,5,8-trimethylpsoralen) plus near-ultraviolet light, and consequently 99.5% inhibition of replicative DNA synthesis is achieved. Additional DNA-damaging agents induce thymidine incorporation into the double-stranded regions of the DNA. The new method gave results very similar to those obtained with the benzoylated naphthoylated DEAE (BND) cellulose method using three human fibroblast strains, of which one had deficient capacity for DNA repair synthesis following treatment with ..gamma.. rays and methyl methanesulfonate. The advantages of the new method are simplicity and rapidity, as well as the high extent to which replicative DNA synthesis is inhibited.

  8. Psoralen plus near-ultraviolet light: a possible new method for measuring DNA repair synthesis

    SciTech Connect

    Heimer, Y.M.; Kol, R.; Shiloh, Y.; Riklis, E.

    1983-09-01

    A new method is proposed to inhibit semiconservative DNA synthesis in cultured cells while DNA repair synthesis is being measured. The cells are treated with the DNA-crosslinking agent Trioxalen (4,5,8-trimethylpsoralen) plus near-ultraviolet light, and consequently 99.5% inhibition of replicative DNA synthesis is achieved. Additional DNA-damaging agents induce thymidine incorporation into the double-stranded regions of the DNA. The new method gave results very similar to those obtained with the benzoylated naphthoylated DEAE (BND) cellulose method using three human fibroblast strains, of which one had deficient capacity for DNA repair synthesis following treatment with gamma rays and methyl methanesulfonate. The advantages of the new method are simplicity and rapidity, as well as the high extent to which replicative DNA synthesis is inhibited.

  9. Improved calibration technique of the infrared imaging bolometer using ultraviolet light-emitting diodes.

    PubMed

    Drapiko, E; Peterson, B; Alekseev, A; Seo, D C

    2010-10-01

    The technique used until recently utilizing the Ne-He laser for imaging bolometer foils calibration [B. J. Peterson et al., J. Plasma Fusion Res. 2, S1018 (2007)] has showed several issues. The method was based on irradiation of 1 cm spaced set of points on a foil by the laser beam moved by set of mirrors. Issues were the nonuniformity of laser power due to the vacuum window transmission nonuniformity and high reflection coefficient for the laser. Also, due to the limited infrared (IR) window size, it was very time consuming. The new methodology uses a compact ultraviolet (uv) light-emitting diodes installed inside the vacuum chamber in a fixed position and the foil itself will be moved in the XY directions by two vacuum feedthroughs. These will help to avoid the above mentioned issues due to lack of a vacuum window, fixed emitters, higher uv power absorption, and a fixed IR camera position.

  10. Advanced Oxidation of Tartrazine and Brilliant Blue with Pulsed Ultraviolet Light Emitting Diodes.

    PubMed

    Scott, Robert; Mudimbi, Patrick; Miller, Michael E; Magnuson, Matthew; Willison, Stuart; Phillips, Rebecca; Harper, Willie F

    2017-01-01

      This study investigated the effect of ultraviolet light-emitting diodes (UVLEDs) coupled with hydrogen peroxide as an advanced oxidation process (AOP) for the degradation of two test chemicals. Brilliant Blue FCF consistently exhibited greater degradation than tartrazine, with 83% degradation after 300 minutes at the 100% duty cycle compared with only 17% degradation of tartrazine under the same conditions. These differences are attributable to the structural properties of the compounds. Duty cycle was positively correlated with the first-order rate constants (k) for both chemicals but, interestingly, negatively correlated with the normalized first-order rate constants (k/duty cycle). Synergistic effects of both hydraulic mixing and LED duty cycle were manifested as novel oscillations in the effluent contaminant concentration. Further, LED output and efficiency were dependent upon duty cycle and less efficient over time perhaps due to heating effects on semiconductor performance.

  11. Giant Surface Conductivity Enhancement in a Carbon Nanotube Composite by Ultraviolet Light Exposure.

    PubMed

    Long, Christian J; Orloff, Nathan D; Twedt, Kevin A; Lam, Thomas; Vargas-Lara, Fernando; Zhao, Minhua; Natarajan, Bharath; Scott, Keana C; Marksz, Eric; Nguyen, Tinh; Douglas, Jack F; McClelland, Jabez; Garboczi, Edward; Obrzut, Jan; Liddle, J Alexander

    2016-09-07

    Carbon nanotube composites are lightweight, multifunctional materials with readily adjustable mechanical and electrical properties-relevant to the aerospace, automotive, and sporting goods industries as high-performance structural materials. Here, we combine well-established and newly developed characterization techniques to demonstrate that ultraviolet (UV) light exposure provides a controllable means to enhance the electrical conductivity of the surface of a commercial carbon nanotube-epoxy composite by over 5 orders of magnitude. Our observations, combined with theory and simulations, reveal that the increase in conductivity is due to the formation of a concentrated layer of nanotubes on the composite surface. Our model implies that contacts between nanotube-rich microdomains dominate the conductivity of this layer at low UV dose, while tube-tube transport dominates at high UV dose. Further, we use this model to predictably pattern conductive traces with a UV laser, providing a facile approach for direct integration of lightweight conductors on nanocomposite surfaces.

  12. Hubble Space Telescope Ultraviolet Light Curves Reveal Interesting Properties of CC Sculptoris and RZ Leonis

    NASA Astrophysics Data System (ADS)

    Szkody, Paula; Mukadam, Anjum S.; Toloza, Odette; Gänsicke, Boris T.; Dai, Zhibin; Pala, Anna F.; Waagen, Elizabeth O.; Godon, Patrick; Sion, Edward M.

    2017-03-01

    Time-tag ultraviolet data obtained on the Hubble Space Telescope in 2013 reveal interesting variability related to the white dwarf spin in the two cataclysmic variables RZ Leo and CC Scl. RZ Leo shows a period at 220 s and its harmonic at 110 s, thus identifying it as a likely Intermediate Polar (IP). The spin signal is not visible in a short single night of ground-based data in 2016, but the shorter exposures in that data set indicate a possible partial eclipse. The much larger UV amplitude of the spin signal in the known IP CC Scl allows the spin of 389 s, previously only seen at outburst, to be visible at quiescence. Spectra created from the peaks and troughs of the spin times indicate a hotter temperature of several thousand degrees during the peak phases, with multiple components contributing to the UV light.

  13. Photolithography reaches 6 nm half-pitch using extreme ultraviolet light

    NASA Astrophysics Data System (ADS)

    Fan, Daniel; Ekinci, Yasin

    2016-07-01

    Extreme ultraviolet interference lithography records the interference pattern of two diffracted, coherent light beams, where the pattern resolution is half the diffraction grating resolution. The fabrication of diffraction grating masks by e-beam lithography is restricted by the electron proximity effect and pattern transfer limitations into diffraction efficient materials. By patterning HSQ lines at a relaxed pitch to avoid the electron proximity effect, depositing conformal iridium via atomic layer deposition, followed by ion milling the top and bottom iridium and HSQ removal, we fabricated iridium diffraction gratings at double the line spacing of the original HSQ lines. Line/space patterns of 6-nm half-pitch patterns were achieved using these masks, marking a new record resolution in photolithography.

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

    NASA Technical Reports Server (NTRS)

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

    1999-01-01

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

  15. Effect of Ultraviolet-A (UV-A) and Ultraviolet-C (UV-C) Light on Mechanical Properties of Oyster Mushrooms during Growth

    PubMed Central

    Edward, Tindibale L.; Kirui, M. S. K.; Omolo, Josiah O.; Ngumbu, Richard G.; Odhiambo, Peter M.

    2014-01-01

    This study investigated the effects of ultraviolet-A (UV-A) and ultraviolet-C (UV-C) light on the mechanical properties in oyster mushrooms during the growth. Experiments were carried out with irradiation of the mushrooms with UV-A (365 nm) and UV-C (254 nm) light during growth. The exposure time ranged from 10 minutes to 60 minutes at intervals of 10 minutes and irradiation was done for three days. The samples for experimental studies were cut into cylindrical shapes of diameter 12.50 mm and thickness 3.00 mm. The storage modulus, loss modulus, and loss factor of the irradiated samples and control samples were determined for both UV bands and there was a significant difference between the storage modulus, loss modulus, and loss factor of the irradiated samples by both UV bands with reference to the control sample, P < 0.05. UV-C light irradiated samples had higher loss modulus and loss factor but low storage modulus as temperature increased from 35 to 100°C with respect to the control sample while UV-A light irradiated samples had lower loss modulus, low loss factor, and higher storage modulus than UV-C irradiated samples. PMID:25580117

  16. Tunnel-injection GaN quantum dot ultraviolet light-emitting diodes

    SciTech Connect

    Verma, Jai; Kandaswamy, Prem Kumar; Protasenko, Vladimir; Verma, Amit; Grace Xing, Huili; Jena, Debdeep

    2013-01-28

    We demonstrate a GaN quantum dot ultraviolet light-emitting diode that uses tunnel injection of carriers through AlN barriers into the active region. The quantum dot heterostructure is grown by molecular beam epitaxy on AlN templates. The large lattice mismatch between GaN and AlN favors the formation of GaN quantum dots in the Stranski-Krastanov growth mode. Carrier injection by tunneling can mitigate losses incurred in hot-carrier injection in light emitting heterostructures. To achieve tunnel injection, relatively low composition AlGaN is used for n- and p-type layers to simultaneously take advantage of effective band alignment and efficient doping. The small height of the quantum dots results in short-wavelength emission and are simultaneously an effective tool to fight the reduction of oscillator strength from quantum-confined Stark effect due to polarization fields. The strong quantum confinement results in room-temperature electroluminescence peaks at 261 and 340 nm, well above the 365 nm bandgap of bulk GaN. The demonstration opens the doorway to exploit many varied features of quantum dot physics to realize high-efficiency short-wavelength light sources.

  17. Transparent ZnO/glass surface acoustic wave based high performance ultraviolet light sensors

    NASA Astrophysics Data System (ADS)

    Wang, Wen-Bo; Gu, Hang; He, Xing-Li; Xuan, Wei-Peng; Chen, Jin-Kai; Wang, Xiao-Zhi; Luo, Ji-Kui

    2015-05-01

    Surface acoustic wave (SAW) resonators are a type of ultraviolet (UV) light sensors with high sensitivity, and they have been extensively studied. Transparent SAW devices are very useful and can be developed into various sensors and microfluidics for sensing/monitoring and lab-on-chip applications. We report the fabrication of high sensitivity SAW UV sensors based on piezoelectric (PE) ZnO thin films deposited on glass substrates. The sensors were fabricated and their performances against the post-deposition annealing condition were investigated. It was found that the UV-light sensitivity is improved by more than one order of magnitude after annealing. The frequency response increases significantly and the response becomes much faster. The optimized devices also show a small temperature coefficient of frequency and excellent repeatability and stability, demonstrating its potential for UV-light sensing application. Project supported by the National Natural Science Foundation of China (Grant Nos. 61274037 and 61301046) and the Research Fund for the Doctoral Program of Higher Education of China (Grant Nos. 20120101110031 and 20120101110054).

  18. Ultraviolet Light Enhances the Bovine Serum Albumin Fixation for Acid Fast Bacilli Stain

    PubMed Central

    Lai, Pei-Yin; Lee, Shih-Yi; Chou, Yu-Ching; Fu, Yung-Chieh; Wu, Chen-Cheng; Chiueh, Tzong-Shi

    2014-01-01

    The use of a liquid culture system such as MGIT broth has greatly improved the sensitivity of isolating mycobacteria in clinical laboratories. Microscopic visualization of acid fast bacilli (AFB) in the culture positive MGIT broth remains the first routine step for rapidly indicating the presence of mycobacteria. We modified an ultraviolet (UV) light fixation process to increase AFB cells adherence to the slide. The retained haze proportion of a 1-cm circle marked area on the smear slide was quantified after the staining procedure indicating the adherence degree of AFB cells. More AFB cells were preserved on the slide after exposure to UV light of either germicidal lamp or UV crosslinker in a time-dependent manner. We demonstrated both the bovine serum albumin (BSA) in MGIT media and UV light exposure were required for enhancing fixation of AFB cells. While applying to AFB stains for 302 AFB positive MGIT broths in clinics, more AFB cells were retained and observed on smear slides prepared by the modified fixation procedure rather than by the conventional method. The modified fixation procedure was thus recommended for improving the sensitivity of microscopic diagnosis of AFB cells in culture positive MGIT broth. PMID:24586725

  19. Mobility of Chromophores Absorbing Light in the 320-420 nm Range in Transparent and Cataract Lens Tissue

    NASA Astrophysics Data System (ADS)

    Halets-Bui, I. V.; Sukhodol, A. A.; Shcharbin, D. G.

    2014-11-01

    We have analyzed the spectral and kinetic characteristics of phosphorescence at room temperature on a millisecond time scale for transparent and cataract lens tissues. We have studied the nature of the change (with age and with cataract development in the lens tissues) in the molecular mobility of the products absorbing light in the 320-420 nm range.

  20. Time Effectiveness of Ultraviolet C Light (UVC) Emitted by Light Emitting Diodes (LEDs) in Reducing Stethoscope Contamination

    PubMed Central

    Messina, Gabriele; Fattorini, Mattia; Nante, Nicola; Rosadini, Daniele; Serafini, Andrea; Tani, Marco; Cevenini, Gabriele

    2016-01-01

    Today it is well demonstrated that stethoscopes can be as contaminated as hands, which are a recognized source of Health-Care Associated Infections (HCAIs). Ultraviolet C (UVC) light has proven disinfection capacity and the innovative UVC technology of Light Emitting Diode (LED) shows several potential benefits. To verify whether the use of UVC LEDs is effective and reliable in stethoscope membrane disinfection after prolonged use, a pre-post intervention study was conducted. A total of 1668 five-minute cycles were performed on two UVC LEDs to simulate their use; thereafter, their disinfection capacity was tested on stethoscope membranes used on a previously auscultated volunteer. Then, a further 1249 cycles were run and finally the LEDs were tested to assess performance in reducing experimental contamination by Staphylococcus aureus, Pseudomonas aeruginosa and Escherichia coli on the stethoscope membrane. Baseline volunteer contamination identified 104 Colony Forming Units (CFUs) while treated Petri dishes had 12 and 15 CFUs (p < 0.001). Statistically significant differences (p < 0.001) were also found relating to the reduction of specific bacteria: in particular, after treatment no CFU were observed for S. aureus and E. coli. UVC LEDs demonstrated the capacity to maintain high levels of disinfection after more than 240 h of use and they were effective against common microorganisms that are causative agents of HCAIs. PMID:27669273

  1. Time Effectiveness of Ultraviolet C Light (UVC) Emitted by Light Emitting Diodes (LEDs) in Reducing Stethoscope Contamination.

    PubMed

    Messina, Gabriele; Fattorini, Mattia; Nante, Nicola; Rosadini, Daniele; Serafini, Andrea; Tani, Marco; Cevenini, Gabriele

    2016-09-23

    Today it is well demonstrated that stethoscopes can be as contaminated as hands, which are a recognized source of Health-Care Associated Infections (HCAIs). Ultraviolet C (UVC) light has proven disinfection capacity and the innovative UVC technology of Light Emitting Diode (LED) shows several potential benefits. To verify whether the use of UVC LEDs is effective and reliable in stethoscope membrane disinfection after prolonged use, a pre-post intervention study was conducted. A total of 1668 five-minute cycles were performed on two UVC LEDs to simulate their use; thereafter, their disinfection capacity was tested on stethoscope membranes used on a previously auscultated volunteer. Then, a further 1249 cycles were run and finally the LEDs were tested to assess performance in reducing experimental contamination by Staphylococcus aureus, Pseudomonas aeruginosa and Escherichia coli on the stethoscope membrane. Baseline volunteer contamination identified 104 Colony Forming Units (CFUs) while treated Petri dishes had 12 and 15 CFUs (p < 0.001). Statistically significant differences (p < 0.001) were also found relating to the reduction of specific bacteria: in particular, after treatment no CFU were observed for S. aureus and E. coli. UVC LEDs demonstrated the capacity to maintain high levels of disinfection after more than 240 h of use and they were effective against common microorganisms that are causative agents of HCAIs.

  2. Reverse-absorbance-modulation-optical lithography for optical nanopatterning at low light levels

    NASA Astrophysics Data System (ADS)

    Majumder, Apratim; Wan, Xiaowen; Masid, Farhana; Pollock, Benjamin J.; Andrew, Trisha L.; Soppera, Olivier; Menon, Rajesh

    2016-06-01

    Absorbance-Modulation-Optical Lithography (AMOL) has been previously demonstrated to be able to confine light to deep sub-wavelength dimensions and thereby, enable patterning of features beyond the diffraction limit. In AMOL, a thin photochromic layer that converts between two states via light exposure is placed on top of the photoresist layer. The long wavelength photons render the photochromic layer opaque, while the short-wavelength photons render it transparent. By simultaneously illuminating a ring-shaped spot at the long wavelength and a round spot at the short wavelength, the photochromic layer transmits only a highly confined beam at the short wavelength, which then exposes the underlying photoresist. Many photochromic molecules suffer from a giant mismatch in quantum yields for the opposing reactions such that the reaction initiated by the absorption of the short-wavelength photon is orders of magnitude more efficient than that initiated by the absorption of the long-wavelength photon. As a result, large intensities in the ring-shaped spot are required for deep sub-wavelength nanopatterning. In this article, we overcome this problem by using the long-wavelength photons to expose the photoresist, and the short-wavelength photons to confine the "exposing" beam. Thereby, we demonstrate the patterning of features as thin as λ/4.7 (137nm for λ = 647nm) using extremely low intensities (4-30 W/m2, which is 34 times lower than that required in conventional AMOL). We further apply a rigorous model to explain our experiments and discuss the scope of the reverse-AMOL process.

  3. Mixed Ge/Pb perovskite light absorbers with an ascendant efficiency explored from theoretical view.

    PubMed

    Sun, Ping-Ping; Li, Quan-Song; Feng, Shuai; Li, Ze-Sheng

    2016-06-07

    Organic-inorganic methylammonium lead halide perovskites have recently attracted great interest emerging as promising photovoltaic materials with a high 20.8% efficiency, but lead pollution is still a problem that may hinder the development and wide spread of MAPbI3 perovskites. To reduce the use of lead, we investigated the structures, electronic and optical properties of mixed MAGexPb(1-x)I3 theoretically by using density functional theory methods at different calculation levels. Results show that the mixed Ge/Pb perovskites exhibit a monotonic decrease evolution in band energy to push the band gap deeper in the near-infrared region and have a red shift optical absorption with an increased proportion of Ge. The results also indicate that lattice distortion and spin-orbit coupling (SOC) strength play important roles in the band gap behavior of MAGexPb(1-x)I3 by affecting the bandwidths of CBM and VBM. The calculations for short circuit current density, open circuit voltage, and theoretical power conversion efficiency suggest that mixed Ge/Pb perovskite solar cells (PSCs) with efficiency over 22% are superior to MAPbI3 and MAGeI3. And notably, MAGe0.75Pb0.25I3 is a promising harmless material for solar cells absorber with the highest theoretical efficiency of 24.24%. These findings are expected to be helpful for further rational design of nontoxic light absorption layer for high-performance PSCs.

  4. Light-absorbing particles in snow and ice: Measurement and modeling of climatic and hydrological impact

    NASA Astrophysics Data System (ADS)

    Qian, Yun; Yasunari, Teppei J.; Doherty, Sarah J.; Flanner, Mark G.; Lau, William K. M.; Ming, Jing; Wang, Hailong; Wang, Mo; Warren, Stephen G.; Zhang, Rudong

    2015-01-01

    Light absorbing particles (LAP, e.g., black carbon, brown carbon, and dust) influence water and energy budgets of the atmosphere and snowpack in multiple ways. In addition to their effects associated with atmospheric heating by absorption of solar radiation and interactions with clouds, LAP in snow on land and ice can reduce the surface reflectance (a.k.a., surface darkening), which is likely to accelerate the snow aging process and further reduces snow albedo and increases the speed of snowpack melt. LAP in snow and ice (LAPSI) has been identified as one of major forcings affecting climate change, e.g. in the fourth and fifth assessment reports of IPCC. However, the uncertainty level in quantifying this effect remains very high. In this review paper, we document various technical methods of measuring LAPSI and review the progress made in measuring the LAPSI in Arctic, Tibetan Plateau and other mid-latitude regions. We also report the progress in modeling the mass concentrations, albedo reduction, radiative forcing, and climatic and hydrological impact of LAPSI at global and regional scales. Finally we identify some research needs for reducing the uncertainties in the impact of LAPSI on global and regional climate and the hydrological cycle.

  5. Light-absorbing Particles in Snow and Ice: Measurement and Modeling of Climatic and Hydrological Impact

    SciTech Connect

    Qian, Yun; Yasunari, Teppei J.; Doherty, Sarah J.; Flanner, M. G.; Lau, William K.; Ming, J.; Wang, Hailong; Wang, Mo; Warren, Stephen G.; Zhang, Rudong

    2015-01-01

    Light absorbing particles (LAP, e.g., black carbon, brown carbon, and dust) influence water and energy budgets of the atmosphere and snowpack in multiple ways. In addition to their effects associated with atmospheric heating by absorption of solar radiation and interactions with clouds, LAP in snow on land and ice can reduce the surface reflectance (a.k.a., surface darkening), which is likely to accelerate the snow aging process and further reduces snow albedo and increases the speed of snowpack melt. LAP in snow and ice (LAPSI) has been identified as one of major forcings affecting climate change, e.g. in the fourth and fifth assessment reports of IPCC. However, the uncertainty level in quantifying this effect remains very high. In this review paper, we document various technical methods of measuring LAPSI and review the progress made in measuring the LAPSI in Arctic, Tibetan Plateau and other mid-latitude regions. We also report the progress in modeling the mass concentrations, albedo reduction, radiative forcing, andclimatic and hydrological impact of LAPSI at global and regional scales. Finally we identify some research needs for reducing the uncertainties in the impact of LAPSI on global and regional climate and the hydrological cycle.

  6. Inactivation of Staphylococcus saprophyticus in chicken meat and exudate using high pressure processing, gamma radiation, and ultraviolet light

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Stapylococcus saprophyticus is a common contaminant in foods and causes urinary tract infections in humans. Three nonthermal food safety intervention technologies used to improve the safety foods include high pressure processing (HPP), ionizing (gamma) radiation (GR), and ultraviolet light (UV-C). A...

  7. EFFECTS OF ULTRAVIOLET-B LIGHT AND POLYAROMATIC HYDROCARBON EXPOSURE ON SEA URCHIN DEVELOPMENT AND BACTERIAL BIOLUMINESCENCE

    EPA Science Inventory

    Polycyclic aromatic hydrocarbons (PAHs) are relatively common contaminants of the Gulf of Mexico and may be activated to more toxic metabolites by ultraviolet-B (UV-B) light. A marine bacterial bioassay system (Vibrio fischeri) which focused on the reduction of luciferase-mediate...

  8. Assessing the effectiveness of low-pressure ultraviolet light for inactivating Mycobacterium avium complex (MAC) micro-organisms

    EPA Science Inventory

    Aims: To assess low-pressure ultraviolet light (LP-UV) inactivation kinetics of Mycobacterium avium complex (MAC) strains in a water matrix using collimated beam apparatus. Methods and Results: Strains of M. avium (n = 3) and Mycobacterium intracellulare (n = 2) were exposed t...

  9. Responses of the picoprasinophyte Micromonas commoda to light and ultraviolet stress.

    PubMed

    Cuvelier, Marie L; Guo, Jian; Ortiz, Alejandra C; van Baren, Marijke J; Tariq, Muhammad Akram; Partensky, Frédéric; Worden, Alexandra Z

    2017-01-01

    Micromonas is a unicellular marine green alga that thrives from tropical to polar ecosystems. We investigated the growth and cellular characteristics of acclimated mid-exponential phase Micromonas commoda RCC299 over multiple light levels and over the diel cycle (14:10 hour light:dark). We also exposed the light:dark acclimated M. commoda to experimental shifts from moderate to high light (HL), and to HL plus ultraviolet radiation (HL+UV), 4.5 hours into the light period. Cellular responses of this prasinophyte were quantified by flow cytometry and changes in gene expression by qPCR and RNA-seq. While proxies for chlorophyll a content and cell size exhibited similar diel variations in HL and controls, with progressive increases during day and decreases at night, both parameters sharply decreased after the HL+UV shift. Two distinct transcriptional responses were observed among chloroplast genes in the light shift experiments: i) expression of transcription and translation-related genes decreased over the time course, and this transition occurred earlier in treatments than controls; ii) expression of several photosystem I and II genes increased in HL relative to controls, as did the growth rate within the same diel period. However, expression of these genes decreased in HL+UV, likely as a photoprotective mechanism. RNA-seq also revealed two genes in the chloroplast genome, ycf2-like and ycf1-like, that had not previously been reported. The latter encodes the second largest chloroplast protein in Micromonas and has weak homology to plant Ycf1, an essential component of the plant protein translocon. Analysis of several nuclear genes showed that the expression of LHCSR2, which is involved in non-photochemical quenching, and five light-harvesting-like genes, increased 30 to >50-fold in HL+UV, but was largely unchanged in HL and controls. Under HL alone, a gene encoding a novel nitrite reductase fusion protein (NIRFU) increased, possibly reflecting enhanced N

  10. Responses of the picoprasinophyte Micromonas commoda to light and ultraviolet stress

    PubMed Central

    Ortiz, Alejandra C.; van Baren, Marijke J.; Tariq, Muhammad Akram; Partensky, Frédéric

    2017-01-01

    Micromonas is a unicellular marine green alga that thrives from tropical to polar ecosystems. We investigated the growth and cellular characteristics of acclimated mid-exponential phase Micromonas commoda RCC299 over multiple light levels and over the diel cycle (14:10 hour light:dark). We also exposed the light:dark acclimated M. commoda to experimental shifts from moderate to high light (HL), and to HL plus ultraviolet radiation (HL+UV), 4.5 hours into the light period. Cellular responses of this prasinophyte were quantified by flow cytometry and changes in gene expression by qPCR and RNA-seq. While proxies for chlorophyll a content and cell size exhibited similar diel variations in HL and controls, with progressive increases during day and decreases at night, both parameters sharply decreased after the HL+UV shift. Two distinct transcriptional responses were observed among chloroplast genes in the light shift experiments: i) expression of transcription and translation-related genes decreased over the time course, and this transition occurred earlier in treatments than controls; ii) expression of several photosystem I and II genes increased in HL relative to controls, as did the growth rate within the same diel period. However, expression of these genes decreased in HL+UV, likely as a photoprotective mechanism. RNA-seq also revealed two genes in the chloroplast genome, ycf2-like and ycf1-like, that had not previously been reported. The latter encodes the second largest chloroplast protein in Micromonas and has weak homology to plant Ycf1, an essential component of the plant protein translocon. Analysis of several nuclear genes showed that the expression of LHCSR2, which is involved in non-photochemical quenching, and five light-harvesting-like genes, increased 30 to >50-fold in HL+UV, but was largely unchanged in HL and controls. Under HL alone, a gene encoding a novel nitrite reductase fusion protein (NIRFU) increased, possibly reflecting enhanced N

  11. Antileishmanial effect of silver nanoparticles and their enhanced antiparasitic activity under ultraviolet light

    PubMed Central

    Allahverdiyev, Adil M; Abamor, Emrah Sefik; Bagirova, Malahat; Ustundag, Cem B; Kaya, Cengiz; Kaya, Figen; Rafailovich, Miriam

    2011-01-01

    Leishmaniasis is a protozoan vector-borne disease and is one of the biggest health problems of the world. Antileishmanial drugs have disadvantages such as toxicity and the recent development of resistance. One of the best-known mechanisms of the antibacterial effects of silver nanoparticles (Ag-NPs) is the production of reactive oxygen species to which Leishmania parasites are very sensitive. So far no information about the effects of Ag-NPs on Leishmania tropica parasites, the causative agent of leishmaniasis, exists in the literature. The aim of this study was to investigate the effects of Ag-NPs on biological parameters of L. tropica such as morphology, metabolic activity, proliferation, infectivity, and survival in host cells, in vitro. Consequently, parasite morphology and infectivity were impaired in comparison with the control. Also, enhanced effects of Ag-NPs were demonstrated on the morphology and infectivity of parasites under ultraviolet (UV) light. Ag-NPs demonstrated significant antileishmanial effects by inhibiting the proliferation and metabolic activity of promastigotes by 1.5- to threefold, respectively, in the dark, and 2- to 6.5-fold, respectively, under UV light. Of note, Ag-NPs inhibited the survival of amastigotes in host cells, and this effect was more significant in the presence of UV light. Thus, for the first time the antileishmanial effects of Ag-NPs on L. tropica parasites were demonstrated along with the enhanced antimicrobial activity of Ag-NPs under UV light. Determination of the antileishmanial effects of Ag-NPs is very important for the further development of new compounds containing nanoparticles in leishmaniasis treatment. PMID:22114501

  12. Monitoring temperature and light exposure of biosamples exposed to ultraviolet and low energy radiation.

    PubMed

    Chen, Hsin-Kai; Waite, Gabi Nindl; Miller, Penney L; Hughes, Ellen F; Waite, Lee R

    2007-01-01

    We previously showed that T-lymphocytes produce catalytic amounts of hydrogen peroxide (H2O2) in a membrane-associated process when irradiated with narrowband ultraviolet B (UVB) light. This form of phototherapy is thought to be highly effective for treatment of inflammatory skin diseases such as psoriasis, but also includes the potential for severe burning and development of skin cancer. Consequently, information on the therapeutic mechanism of narrowband UVB phototherapy and its regulation is warranted. Our laboratory is researching the mechanistic involvement of T-cell H2O2 production and its potential regulation by low energy electromagnetic field (EMF) radiation, which has been shown to beneficially influence inflammatory diseases such as psoriasis. To study photochemical H2O2 production in small samples such as suspensions of T-lymphocyte cell extracts, we use a reactor in which 12 microliter-sized samples are exposed to UVB. We simultaneously operate two identical systems, one for experimental, the other for control samples, within a walk-in environmental chamber maintained at 37 degrees C. The current paper addresses the control of UVB light exposure and temperature in our experimental setup. We quantified UVB light b y radiometric sp ot measurements and by chemical potassium ferrioxalate actinometry. We modified the actinometer so that UVB light of 5-hour experiments could be detected. Temperature was controlled by air convection and remained constant within 0.5 degrees C in air and liquid samples. Preliminary data of the effect of low energy EMF radiation on T-cell H2O2 production are presented.

  13. Ultraviolet Extensions

    NASA Technical Reports Server (NTRS)

    2008-01-01

    [figure removed for brevity, see original site] Side-by-Side Comparison Click on image for larger view

    This ultraviolet image from NASA's Galaxy Evolution Explorer shows the Southern Pinwheel galaxy, also know as Messier 83 or M83. It is located 15 million light-years away in the southern constellation Hydra.

    Ultraviolet light traces young populations of stars; in this image, young stars can be seen way beyond the main spiral disk of M83 up to 140,000 light-years from its center. Could life exist around one of these far-flung stars? Scientists say it's unlikely because the outlying regions of a galaxy are lacking in the metals required for planets to form.

    The image was taken at scheduled intervals between March 15 and May 20, 2007. It is one of the longest-exposure, or deepest, images ever taken of a nearby galaxy in ultraviolet light. Near-ultraviolet light (or longer-wavelength ultraviolet light) is colored yellow, and far-ultraviolet light is blue.

    What Lies Beyond the Edge of a Galaxy The side-by-side comparison shows the Southern Pinwheel galaxy, or M83, as seen in ultraviolet light (right) and at both ultraviolet and radio wavelengths (left). While the radio data highlight the galaxy's long, octopus-like arms stretching far beyond its main spiral disk (red), the ultraviolet data reveal clusters of baby stars (blue) within the extended arms.

    The ultraviolet image was taken by NASA's Galaxy Evolution Explorer between March 15 and May 20, 2007, at scheduled intervals. Back in 2005, the telescope first photographed M83 over a shorter period of time. That picture was the first to reveal far-flung baby stars forming up to 63,000 light-years from the edge of the main spiral disk. This came as a surprise to astronomers because a galaxy's outer territory typically lacks high densities of star-forming materials.

    The newest picture of M83 from the Galaxy Evolution Explorer is shown at the right, and was taken over a longer period of

  14. Modeling investigation of light-absorbing aerosols in the Amazon Basin during the wet season

    NASA Astrophysics Data System (ADS)

    Wang, Qiaoqiao; Saturno, Jorge; Chi, Xuguang; Walter, David; Lavric, Jost V.; Moran-Zuloaga, Daniel; Ditas, Florian; Pöhlker, Christopher; Brito, Joel; Carbone, Samara; Artaxo, Paulo; Andreae, Meinrat O.

    2016-11-01

    We use a global chemical transport model (GEOS-Chem) to interpret observed light-absorbing aerosols in Amazonia during the wet season. Observed aerosol properties, including black carbon (BC) concentration and light absorption, at the Amazon Tall Tower Observatory (ATTO) site in the central Amazon have relatively low background levels but frequently show high peaks during the study period of January-April 2014. With daily temporal resolution for open fire emissions and modified aerosol optical properties, our model successfully captures the observed variation in fine/coarse aerosol and BC concentrations as well as aerosol light absorption and its wavelength dependence over the Amazon Basin. The source attribution in the model indicates the important influence of open fire on the observed variances of aerosol concentrations and absorption, mainly from regional sources (northern South America) and from northern Africa. The contribution of open fires from these two regions is comparable, with the latter becoming more important in the late wet season. The analysis of correlation and enhancement ratios of BC versus CO suggests transport times of < 3 days for regional fires and ˜ 11 days for African plumes arriving at ATTO during the wet season. The model performance of long-range transport of African plumes is also evaluated with observations from AERONET, MODIS, and CALIOP. Simulated absorption aerosol optical depth (AAOD) averaged over the wet season is lower than 0.0015 over the central Amazon, including the ATTO site. We find that more than 50 % of total absorption at 550 nm is from BC, except for the northeastern Amazon and the Guianas, where the influence of dust becomes significant (up to 35 %). The brown carbon contribution is generally between 20 and 30 %. The distribution of absorption Ångström exponents (AAE) suggests more influence from fossil fuel combustion in the southern part of the basin (AAE ˜ 1) but more open fire and dust influence in the

  15. Finite-Difference Time Domain Solution of Light Scattering and Absorption by Particles in an Absorbing Medium

    NASA Technical Reports Server (NTRS)

    Sun, W.; Loeb, N. G.; Fu, Q.

    2002-01-01

    The three-dimensional (3-D) finite-difference time-domain (FDTD) technique has been extended to simulate light scattering and absorption by nonspherical particles embedded in an absorbing dielectric medium. A uniaxial perfectly matched layer (UPML) absorbing boundary condition is used to truncate the computational domain. When computing the single-scattering properties of a particle in an absorbing dielectric medium, we derive the single-scattering properties including scattering phase functions, extinction, and absorption efficiencies using a volume integration of the internal field. A Mie solution for light scattering and absorption by spherical particles in an absorbing medium is used to examine the accuracy of the 3-D UPML FDTD code. It is found that the errors in the extinction and absorption efficiencies from the 3-D UPML FDTD are less than similar to 2%. The errors in the scattering phase functions are typically less than similar to 5%. The errors in the asymmetry factors are less than similar to 0.l%. For light scattering by particles in free space, the accuracy of the 3-D UPML FDTD scheme is similar to a previous model.

  16. Characterizing mid-ultraviolet to optical light curves of nearby type IIn supernovae

    SciTech Connect

    de la Rosa, Janie; Roming, Pete; Pritchard, Tyler; Fryer, Chris

    2016-03-21

    Here, we present early mid-ultraviolet and optical observations of Type IIn supernovae (SNe IIn) observed from 2007 to 2013. Our results focus on the properties of UV light curves: peak absolute magnitudes, temporal decay, and color evolution. During early times, this sample demonstrates that UV light decays faster than optical, and each event transitions from a predominantly UV-bright phase to an optically bright phase. In order to understand early UV behavior, we generate and analyze the sample's blackbody luminosity, temperature, and radius as the SN ejecta expand and cool. Since most of our observations were detected post maximum luminosity, we introduce a method for estimating the date of peak magnitude. When our observations are compared based on filter, we find that even though these SNe IIn vary in peak magnitudes, there are similarities in UV decay rates. We use a simple semi-analytical SN model in order to understand the effects of the explosion environment on our UV observations. Understanding the UV characteristics of nearby SNe IIn during an early phase can provide valuable information about the environment surrounding these explosions, leading us to evaluating the diversity of observational properties in this subclass.

  17. Characterizing mid-ultraviolet to optical light curves of nearby type IIn supernovae

    DOE PAGES

    de la Rosa, Janie; Roming, Pete; Pritchard, Tyler; ...

    2016-03-21

    Here, we present early mid-ultraviolet and optical observations of Type IIn supernovae (SNe IIn) observed from 2007 to 2013. Our results focus on the properties of UV light curves: peak absolute magnitudes, temporal decay, and color evolution. During early times, this sample demonstrates that UV light decays faster than optical, and each event transitions from a predominantly UV-bright phase to an optically bright phase. In order to understand early UV behavior, we generate and analyze the sample's blackbody luminosity, temperature, and radius as the SN ejecta expand and cool. Since most of our observations were detected post maximum luminosity, wemore » introduce a method for estimating the date of peak magnitude. When our observations are compared based on filter, we find that even though these SNe IIn vary in peak magnitudes, there are similarities in UV decay rates. We use a simple semi-analytical SN model in order to understand the effects of the explosion environment on our UV observations. Understanding the UV characteristics of nearby SNe IIn during an early phase can provide valuable information about the environment surrounding these explosions, leading us to evaluating the diversity of observational properties in this subclass.« less

  18. Pulsed Ultraviolet Light Reduces Immunoglobulin E Binding to Atlantic White Shrimp (Litopenaeus setiferus) Extract

    PubMed Central

    Shriver, Sandra; Yang, Wade; Chung, Si-Yin; Percival, Susan

    2011-01-01

    Pulsed ultraviolet light (PUV), a novel food processing and preservation technology, has been shown to reduce allergen levels in peanut and soybean samples. In this study, the efficacy of using PUV to reduce the reactivity of the major shrimp allergen, tropomyosin (36-kDa), and to attenuate immunoglobulin E (IgE) binding to shrimp extract was examined. Atlantic white shrimp (Litopenaeus setiferus) extract was treated with PUV (3 pulses/s, 10 cm from light source) for 4 min. Tropomyosin was compared in the untreated, boiled, PUV-treated and [boiled+PUV]-treated samples, and changes in the tropomyosin levels were determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). IgE binding of the treated extract was analyzed via immunoblot and enzyme-linked immunosorbent assay (ELISA) using pooled human plasma containing IgE antibodies against shrimp allergens. Results showed that levels of tropomyosin and IgE binding were reduced following PUV treatment. However, boiling increased IgE binding, while PUV treatment could offset the increased allergen reactivity caused by boiling. In conclusion, PUV treatment reduced the reactivity of the major shrimp allergen, tropomyosin, and decreased the IgE binding capacity of the shrimp extract. PMID:21845146

  19. Development of substrate-removal-free vertical ultraviolet light-emitting diode (RefV-LED)

    SciTech Connect

    Kurose, N. Aoyagi, Y.; Shibano, K.; Araki, T.

    2014-02-15

    A vertical ultraviolet (UV) light-emitting diode (LED) that does not require substrate removal is developed. Spontaneous via holes are formed in n-AlN layer epitaxially grown on a high conductive n+Si substrate and the injected current flows directly from the p-electrode to high doped n{sup +} Si substrate through p-AlGaN, multi-quantum wells, n-AlGaN and spontaneous via holes in n-AlN. The spontaneous via holes were formed by controlling feeding-sequence of metal-organic gas sources and NH{sub 3} and growth temperature in MOCVD. The via holes make insulating n-AlN to be conductive. We measured the current-voltage, current-light intensity and emission characteristics of this device. It exhibited a built-in voltage of 3.8 V and emission was stated at 350 nm from quantum wells with successive emission centered at 400 nm. This UV LED can be produced, including formation of n and p electrodes, without any resist process.

  20. Phototoxicology. 2. Near-ultraviolet light enhancement of Microtox assays of trinitrotoluene and aminodinitrotoluenes.

    PubMed

    Johnson, L R; Davenport, R; Balbach, H; Schaeffer, D J

    1994-02-01

    Coexposure of 2,4,6-trinitrotoluene (TNT), 2-amino-4,6-dinitrotoluene (2A), or 4-amino-2,6-dinitrotoluene (4A) to near-ultraviolet (nuv) light (lambda max-354 nm) significantly enhanced their toxicity toward Photobacterium phosphoreum (Microtox bioassay) during 30 min but not 15 min. Based on the slopes of the dose-response lines, the nuv coexposure and dark toxic mechanisms of action for TNT, 2A, and 4A appeared to be similar. nuv coexposure of binary mixtures significantly enhanced (supraadditivity) the toxicity of these compounds to P. phosphoreum. Under normal laboratory lighting, the toxicity of TNT + 2A and 2A + 4A mixtures were supraadditive but the toxicity of TNT + 4A mixtures could be explained by simple addition. Supporting these conclusions, the response curves of alpha-terthienyl, a compound known not to require nuv for toxicity, were similar in the dark and with nuv coexposure. In contrast, angelicin and psoralen, compounds known to require nuv coexposure to damage DNA, gave response curves having different slopes in the dark and with nuv coexposure. The nuv coexposure Microtox assay was able to detect and quantify phototoxicity in psoralen, angelicin, alpha-terthienyl, anthracene, TNT, and aminodinitrotoluenes.

  1. Characterization of material ablation driven by laser generated intense extreme ultraviolet light

    SciTech Connect

    Tanaka, Nozomi Masuda, Masaya; Deguchi, Ryo; Murakami, Masakatsu; Fujioka, Shinsuke; Yogo, Akifumi; Nishimura, Hiroaki; Sunahara, Atsushi

    2015-09-14

    We present a comparative study on the hydrodynamic behaviour of plasmas generated by material ablation by the irradiation of nanosecond extreme ultraviolet (EUV or XUV) or infrared laser pulses on solid samples. It was clarified that the difference in the photon energy deposition and following material heating mechanism between these two lights result in the difference in the plasma parameters and plasma expansion characteristics. Silicon plate was ablated by either focused intense EUV pulse (λ = 9–25 nm, 10 ns) or laser pulse (λ = 1064 nm, 10 ns), both with an intensity of ∼10{sup 9 }W/cm{sup 2}. Both the angular distributions and energy spectra of the expanding ions revealed that the photoionized plasma generated by the EUV light differs significantly from that produced by the laser. The laser-generated plasma undergoes spherical expansion, whereas the EUV-generated plasma undergoes planar expansion in a comparatively narrow angular range. It is presumed that the EUV radiation is transmitted through the expanding plasma and directly photoionizes the samples in the solid phase, consequently forming a high-density and high-pressure plasma. Due to a steep pressure gradient along the direction of the target normal, the EUV plasma expands straightforward resulting in the narrower angular distribution observed.

  2. Near-Ultraviolet Light-Emitting Devices Using Vertical ZnO Nanorod Arrays

    NASA Astrophysics Data System (ADS)

    Jha, S.; Wang, C. D.; Luan, C. Y.; Liu, C. P.; Bin, H.; Kutsay, O.; Bello, I.; Zapien, J. A.; Zhang, W. J.; Lee, S. T.

    2012-05-01

    Reports on electroluminescence (EL) in solid-state, nanomaterial-based devices emitting in the lower wavelength range of the visible spectrum are limited, and the emission stability of these devices is rarely reported. We have fabricated light-emitting devices (LEDs) based on integration of n-ZnO nanorods and p-GaN films, which emit in the violet to near-ultraviolet (NUV) region. We also present data on the stability of EL in fabricated devices. Vertical arrays on ZnO nanorods, with estimated ZnO nanorod density ~108 cm-2, were grown on p-GaN films with typical length of ~4 μm and width of ~120 nm. The NUV LEDs show low turn-on voltage (~3.0 V), small reverse saturation current (~10 μA), and more than two orders of magnitude rectification ratio, all of which indicates a good-quality p- n junction at the p-GaN/ n-ZnO nanorod interface. The EL spectra of LEDs present an emission band centered at ~403 nm. Gaussian fitting of the EL peak revealed three emission peaks at 378 nm, 405 nm, and 431 nm with dominant emission in the NUV region. Significantly, the fabricated NUV LEDs present stable and repeatable EL characteristics, as revealed by bias-stress stability tests. The good electrical properties and stable EL performance make these nanostructure-based NUV LEDs potential candidates for mass production of next-generation lighting devices.

  3. Constraints on decaying neutrinos from the far-ultraviolet extragalactic background light

    NASA Technical Reports Server (NTRS)

    Overduin, J. M.; Wesson, P. S.; Bowyer, S.

    1993-01-01

    We consider light neutrinos as dark matter candidates, concentrating on those proposed by Sciama, with rest energies near 30 eV and decay lifetimes of (2 +/- 1) x 10 exp 23 s. Using equations developed by Wesson et al. (1987) for the visible extragalactic background light, and assuming that the neutrinos are clustered in galactic halos similar to that around our own Galaxy, we show that their decay would be capable of significant contributions to the far-ultraviolet background. Observations in this region by Martin and Bowyer (1989) limit the possible mass of the neutrino halos to 2 x 10 exp 11 M(solar), which is less than the required galactic 'missing mass'. In order to form galactic halos of mass 5 x 10 exp 11 M(solar), such neutrinos would have to decay with lifetimes of at least 3 x 10 exp 23 s to be consistent with the observations. Sciama's proposal remains marginally viable, but more observational data will test it and similar neutrino models critically.

  4. CHARACTERIZING MID-ULTRAVIOLET TO OPTICAL LIGHT CURVES OF NEARBY TYPE IIn SUPERNOVAE

    SciTech Connect

    De la Rosa, Janie; Roming, Pete; Pritchard, Tyler; Fryer, Chris

    2016-03-20

    We present early mid-ultraviolet and optical observations of Type IIn supernovae (SNe IIn) observed from 2007 to 2013. Our results focus on the properties of UV light curves: peak absolute magnitudes, temporal decay, and color evolution. During early times, this sample demonstrates that UV light decays faster than optical, and each event transitions from a predominantly UV-bright phase to an optically bright phase. In order to understand early UV behavior, we generate and analyze the sample's blackbody luminosity, temperature, and radius as the SN ejecta expand and cool. Since most of our observations were detected post maximum luminosity, we introduce a method for estimating the date of peak magnitude. When our observations are compared based on filter, we find that even though these SNe IIn vary in peak magnitudes, there are similarities in UV decay rates. We use a simple semi-analytical SN model in order to understand the effects of the explosion environment on our UV observations. Understanding the UV characteristics of nearby SNe IIn during an early phase can provide valuable information about the environment surrounding these explosions, leading us to evaluating the diversity of observational properties in this subclass.

  5. Deep-ultraviolet-light-driven reversible doping of WS2 field-effect transistors.

    PubMed

    Iqbal, Muhammad Waqas; Iqbal, Muhammad Zahir; Khan, Muhammad Farooq; Shehzad, Muhammad Arslan; Seo, Yongho; Eom, Jonghwa

    2015-01-14

    Improvement of the electrical and photoelectric characteristics is essential to achieve an advanced performance of field-effect transistors and optoelectronic devices. Here we have developed a doping technique to drastically improve electrical and photoelectric characteristics of single-layered, bi-layered and multi-layered WS2 field-effect transistors (FET). After illuminating with deep ultraviolet (DUV) light in a nitrogen environment, WS2 FET shows an enhanced charge carrier density, mobility and photocurrent response. The threshold voltage of WS2 FET shifted toward the negative gate voltage, and the positions of E and A1g peaks in Raman spectra shifted toward lower wavenumbers, indicating the n-type doping effect of the WS2 FET. The doping effect is reversible. The pristine characteristics of WS2 FET can be restored by DUV light illumination in an oxygen environment. The DUV-driven doping technique in a gas environment provides a very stable, effective, easily applicable way to enhance the performance of WS2 FET.

  6. Wettability control of a polymer surface through 126 nm vacuum ultraviolet light irradiation

    NASA Astrophysics Data System (ADS)

    Hozumi, Atsushi; Shirahata, Naoto; Nakanishi, Youichiro; Asakura, Shuuichi; Fuwa, Akio

    2004-07-01

    The control of the surface wettability of poly (methyl methacrylate) (PMMA) substrates has been successfully demonstrated using an Ar2* excimer lamp radiating 126 nm vacuum ultraviolet (VUV) light. Each of the samples was exposed to 126 nm VUV light in air over the pressure range of 2×10-4-105 Pa. Although at the process pressures of 10, 103, and 105 Pa, the PMMA surfaces became relatively hydrophilic, the degree of hydrophilicity depended markedly on the pressure. The minimum water contact angles of the samples treated at 10, 103, and 105 Pa were about 50°, 33°, and 64°, respectively. These values were larger than those of PMMA substrates hydrophilized through 172 nm VUV irradiation conducted under the same conditions. On the other hand, after 126 nm VUV irradiation conducted under the high vacuum condition of 2×10-4 Pa, the PMMA substrate surface became carbon-rich, probably due to preferential cross-linking reactions, as evidenced by x-ray photoelectron spectroscopy. This surface was hydrophobic, showing a water contact angle of about 101°. Although the 126 nm VUV-irradiated surfaces appeared relatively smooth when observed by atomic force microscope, very small particles with diameters of 30-60 nm, which probably originated from the readhesion of photodecomposed products, existed on all of the sample surfaces. .

  7. A New Pathway to Aspartic Acid from Urea and Maleic Acid Affected by Ultraviolet Light

    NASA Astrophysics Data System (ADS)

    Terasaki, Masanori; Nomoto, Shinya; Mita, Hajime; Shimoyama, Akira

    2002-04-01

    The photochemistry of a mixture of urea and maleic acid, which are thought to have been widely present on the primitive Earth, was studied in order to examine a possibility of the formation of amino acids. When an aqueous solution of urea and maleic acid was irradiated with an ultraviolet light of wavelength 172 nm, urea was revealed to be rather resistant to photochemical decomposition. In contrast, maleic acid was completely decomposed within 4 h, reflecting the reactivity of a C-C double bond in the molecule. In the reaction mixture, 2-isoureidosuccinic acid was detected. The acid was considered to be formed by addition of an isoureido radical which had been produced from urea by the action of a hydroxyl radical, to a C-C double bond of maleic acid. The isoureido group of the product was revealed to undergo thermal rearrangement to afford 2-ureidosuccinic acid (N-carbamoylaspartic acid). The result suggested a novel pathway leading to the formation of aspartic acid from non-amino acid precursors, possibly effected by UV-light on the primitive Earth. The formation of ureidocarboxylic acids is of another significance, since they are capable of undergoing thermal polymerization, resulting in formation of polyamino acids.

  8. Efficient photochemical generation of peroxycarboxylic nitric anhydrides with ultraviolet light-emitting diodes

    NASA Astrophysics Data System (ADS)

    Rider, N. D.; Taha, Y. M.; Odame-Ankrah, C. A.; Huo, J. A.; Tokarek, T. W.; Cairns, E.; Moussa, S. G.; Liggio, J.; Osthoff, H. D.

    2015-07-01

    Photochemical sources of peroxycarboxylic nitric anhydrides (PANs) are utilized in many atmospheric measurement techniques for calibration or to deliver an internal standard. Conventionally, such sources rely on phosphor-coated low-pressure mercury (Hg) lamps to generate the UV light necessary to photo-dissociate a dialkyl ketone (usually acetone) in the presence of a calibrated amount of nitric oxide (NO) and oxygen (O2). In this manuscript, a photochemical PAN source in which the Hg lamp has been replaced by arrays of ultraviolet light-emitting diodes (UV-LEDs) is described. The output of the UV-LED source was analyzed by gas chromatography (PAN-GC) and thermal dissociation cavity ring-down spectroscopy (TD-CRDS). Using acetone, diethyl ketone (DIEK), diisopropyl ketone (DIPK), or di-n-propyl ketone (DNPK), respectively, the source produces peroxyacetic (PAN), peroxypropionic (PPN), peroxyisobutanoic (PiBN), or peroxy-n-butanoic nitric anhydride (PnBN) from NO in high yield (> 90 %). Box model simulations with a subset of the Master Chemical Mechanism (MCM) were carried out to rationalize product yields and to identify side products. The present work demonstrates that UV-LED arrays are a viable alternative to current Hg lamp setups.

  9. Photochemical abiotic synthesis of amino-acid precursors from simulated planetary atmospheres by vacuum ultraviolet light

    NASA Astrophysics Data System (ADS)

    Takahashi, Jun-Ichi; Masuda, Hitomi; Kaneko, Takeo; Kobayashi, Kensei; Saito, Takeshi; Hosokawa, Teruo

    2005-07-01

    For the purpose of investigating the photon energy dependence of the photoinduced abiotic synthesis of organic molecules, gas mixtures that simulate typical planetary atmospheres, including a carbon source (CO or CH4), a nitrogen source (N2 or NH3), and H2O, were irradiated with synchrotron radiation through a vacuum-ultraviolet transmitting window. Three kinds of window material, fused silica, synthetic quartz, and MgF2, were used as a high-energy-cutting filter, whose absorption-edge energies are 6.4, 8.1, and 10.5 eV, respectively. Three types of gas mixture, Titan-type (CH4-N2-H2O), comet-type (CO-NH3-H2O), and primitive-Earth-type (CO-N2-H2O), were irradiated with vacuum-ultraviolet photons in the three energy ranges. After the irradiation, amino-acid formation yields in the acid-hydrolyzed solution of the product were measured with a high-performance liquid chromatograph method. From the Titan- and comet-type mixtures, amino acids were detected by irradiation with photons lower than 8.1 eV. For both mixtures, the averaged quantum yields of glycine generation in the photon energy region of 7-10.5 eV were of the order of 10-5, which was larger by about one order than that in the region 5-8 eV. On the other hand, from the primitive-Earth-type mixture, amino-acid formation was difficult to detect even with irradiation as high as 10.5 eV, even though amino acids were generated in comparable yields from the Titan- and comet-type mixtures by irradiation with soft x rays or proton beam, whose energies are much higher. These results suggest that the vacuum ultraviolet light is a more effective energy source for the generation of the precursors of bioorganic compounds in extraterrestrial environments than in primitive-Earth atmosphere.

  10. Photoluminescence performance of thulium doped Li{sub 4}SrCa(SiO{sub 4}){sub 2} under irradiation of ultraviolet and vacuum ultraviolet lights

    SciTech Connect

    Wang, Zhaofeng; Li, Yezhou; Liu, Xiong; Wei, Xingmin; Chen, Yueling; Zhou, Fei; Wang, Yuhua

    2014-11-15

    Highlights: • A novel blue-emitting phosphor Li{sub 4}SrCa(SiO{sub 4}){sub 2}:Tm{sup 3+} was reported. • Li{sub 4}SrCa(SiO{sub 4}){sub 2}:Tm{sup 3+} exhibited excellent thermal and irradiation stability. • Li{sub 4}SrCa(SiO{sub 4}){sub 2}:Tm{sup 3+} was found to possess high color purity. - Abstract: In this work, we synthesized Tm{sup 3+} doped Li{sub 4}SrCa(SiO{sub 4}){sub 2} phosphors and investigated their photoluminescence properties under the excitation of ultraviolet and vacuum ultraviolet lights. The crystal structure analysis and variation of cell parameters confirm that Tm{sup 3+} ions have been successfully doped in the structure of Li{sub 4}SrCa(SiO{sub 4}){sub 2} host by occupying the sites of Ca{sup 2+} with the coordination number of 6. The luminescence results suggest that Li{sub 4}SrCa(SiO{sub 4}){sub 2}:Tm{sup 3+} is a good blue-emitting phosphor when excited by ultraviolet and vacuum ultraviolet irradiations. In addition, it is observed that there is nearly no degradation for Li{sub 4}SrCa(SiO{sub 4}){sub 2}:Tm{sup 3+} after undergoing thermal and irradiation treatments. Possible mechanisms for the luminescence processes are proposed on the basis of the discussion of excitation and emission spectra. In particular, the emission color of Li{sub 4}SrCa(SiO{sub 4}){sub 2}:Tm{sup 3+} by excitation of 147 and 172 nm irradiations is very close to the standard blue color, suggesting that it could be potentially applied in plasma display panels and mercury-free fluorescence lamps.

  11. Luminescent properties of Pr{sup 3+}-sensitized LaPO{sub 4}:Gd{sup 3+} ultraviolet-B phosphor under vacuum-ultraviolet light excitation

    SciTech Connect

    Okamoto, Shinji; Uchino, Rika; Kobayashi, Keisuke; Yamamoto, Hajime

    2009-07-01

    Luminescent properties of Pr{sup 3+}-sensitized LaPO{sub 4}:Gd{sup 3+} under vacuum-ultraviolet (vuv) light excitation have been investigated. The energy transfer probably occurs from the 5d levels in Pr{sup 3+} ions to Gd{sup 3+} ions under 172 nm light excitation. LaPO{sub 4}:Gd{sup 3+},Pr{sup 3+} shows efficient ultraviolet-B (uv-B) emission at 312 nm, whose peak intensity reaches its maximum at Gd=35 mol % and Pr=5 mol %. (La{sub 0.65}Gd{sub 0.35}){sub 0.95}Pr{sub 0.05}PO{sub 4} is about 1.6 times higher than a typical uv-B phosphor for vuv lamp, Y{sub 0.75}Gd{sub 0.25}Al{sub 3}(BO{sub 3}){sub 4}, in Gd{sup 3+}-emission intensity under 172 nm light excitation. This result implies that the Pr{sup 3+}-sensitized LaPO{sub 4}:Gd{sup 3+} is a candidate of uv-B phosphors for xenon-excimer discharge vuv lamps. In order to evaluate the effect of the narrow-band uv-B emission by LaPO{sub 4}:Gd{sup 3+},Pr{sup 3+} phosphor, irradiation test on DNA was performed. The irradiation damage of pUC 18 DNA by the narrow-band uv-B light from the LaPO{sub 4}:Gd{sup 3+},Pr{sup 3+} phosphor is in the same magnitude as that by uv-A light from a filtered Hg lamp, even though the uv-B lamp is higher than the uv-A lamp in power density and photon energy.

  12. 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.

  13. Partitioning of absorbed light energy differed between the sun-exposed side and the shaded side of apple fruits under high light conditions.

    PubMed

    Chen, Changsheng; Zhang, Di; Li, Pengmin; Ma, Fengwang

    2012-11-01

    Fractions of absorbed light energy consumed via photochemistry and different thermal dissipation processes was quantified and compared between the sun-exposed peel and the shaded peel of apple fruits at different developmental stages. During fruit development, the fraction of absorbed light consumed via photochemistry was no more than 7% in the sun-exposed peel and no more than 5% in the shaded peel under high light conditions. Under high light, the fraction of absorbed light energy consumed via light dependent thermal dissipation was higher whereas that via constitutive thermal dissipation was lower in the sun-exposed peel. The light dependent thermal dissipation in the sun-exposed peel mainly depended on the xanthophyll cycle, and the xanthophyll cycle pool size was significantly larger in the sun-exposed peel than in the shaded peel. The light dependent thermal dissipation in the shaded peel was dependent on both the xanthophyll cycle and the presence of inactivated reaction centers. Under high light conditions, the densities of both Q(A)-reducing reaction centers and Q(B)-reducing reaction centers decreased faster in the shaded peel than in the sun-exposed peel. The thermal dissipation related to photoinhibition increased and then kept unchanged in the sun-exposed peel but decreased in the shaded peel during fruit development. We conclude that under high light intensities, fruit peel looses the excess energy in order of predominance: first by the xanthophyll cycle, then the thermal dissipation related to photoinhibition, next through inactivated reaction centers, and finally by constitutive thermal dissipation.

  14. Persistence, temporal and spatial profiles of ultraviolet absorbents and phenolic personal care products in riverine and estuarine sediment of the Pearl River catchment, China.

    PubMed

    Peng, Xianzhi; Xiong, Songsong; Ou, Weihui; Wang, Zhifang; Tan, Jianhua; Jin, Jiabin; Tang, Caiming; Liu, Jun; Fan, Yujuan

    2017-02-05

    A variety of personal care products have been classified as emerging contaminants (ECs). Occurrence, fate, spatial and vertical profiles of 13 ultraviolet absorbents, triclocarban (TCC) and its dechlorinated products, triclosan (TCS), 2-phenylphenol and parabens were investigated in riverine and estuarine sediment of the Pearl River catchment, China. Bisphenol A (BPA), a widely applied plasticizer, was also investigated. The ECs were widely present in the bed sediment. TCC was the most abundant with a maximum concentration of 332ngg(-1) dry weight. The other prominent ECs included BPA, TCS, octocrylene, and benzotriazole UV stabilizers UV326 and UV328. Treated wastewater effluent was the major source of the ECs in the riverine sediment. TCC, BPA, TCS, methyparaben, UV531, UV326, and UV328 were also detected throughout the estuarine sediment cores, indicating their persistence in the sediment. Temporal trends of the ECs in the sediment cores reflected a combined effect of industrial development, population growth, human life quality improvement, and waste treatment capacity in the Pearl River Delta over the last decades. TCC dechlorination products were frequently detected in the bed sediment with higher levels near treated effluent outlets but only occasionally observed in the sediment cores, suggesting insignificant in-situ TCC dechlorination in the sediment.

  15. Ultra-light weight undamped tuned dynamic absorber for cryogenically cooled infrared electro-optic payload

    NASA Astrophysics Data System (ADS)

    Veprik, Alexander; Babitsky, Vladimir

    2017-04-01

    Attenuation of tonal cryocooler induced vibration in infrared electro-optical payloads may be achieved by using of Tuned Dynamic Absorber (TDA) which is, generally speaking, a passive, weakly damped mass-spring system the resonant frequency of which is precisely matched with the driving frequency. Added TDA results in a favorable modification of the frequency response functions of combined structure. In particular, a favorable antiresonant notch appears at the frequency of tonal excitation along with the adjacent secondary resonance, the width and depth of which along with its closeness to the secondary resonance are strongly dependent on the mass and damping ratios. Using heavier TDA favorably results in wider and deeper antiresonant notch along with increased gap between antiresonant and resonant frequencies. Lowering damping in TDA favorably results in deepening the antiresonant notch. The weight of TDA is usually subjected to tight design constrains. Use of lightweight TDA not only diminishes the attainable performance but also complicates the procedure of frequency matching. Along these lines, even minor frequency deviations may negate the TDA performance and even result in TDA failure in case of resonant build up. The authors are presenting theoretical and practical aspects of designing and constructing ultra-light weight TDA in application to vibration attenuation of electro-optical infrared payload relying on Split Stirling linear cryocooler, the driving frequency of which is fixed and may be accurately tuned and maintained using a digital controller over the entire range of working conditions and lifetime; the lack of mass ratio is compensated by minimizing the damping ratio. In one particular case, in excess of 100-fold vibration attenuation has been achieved by adding as little as 5% to the payload weight.

  16. Effects of the novel poly(methyl methacrylate) (PMMA)-encapsulated organic ultraviolet (UV) filters on the UV absorbance and in vitro sun protection factor (SPF).

    PubMed

    Wu, Pey-Shiuan; Huang, Lan-Ni; Guo, Yi-Cing; Lin, Chih-Chien

    2014-02-05

    Sunscreens are thought to protect skin from many of the harmful effects of ultraviolet (UV) light and the photostability of sunscreens is thus an important concern in their application. Therefore, to discover new UV filters or to modify well-known UV filters are presents an important way for development of sunscreens. In this study, we presented several novel poly(methyl methacrylate) (PMMA) encapsulated organic UV filters, including encapsulated benzophenone-3 (TB-MS), avobenzone (TA-MS), octyl methoxycinnamate (TO-MS) and diethylamino hydroxybenzoyl hexyl benzoate (TD-MS). Our results have demonstrated that PMMA-encapsulated UV filters have improved safety, photoprotective ability and photostability. We proposed therefore that these PMMA-encapsulated UV filters can be used as ingredients for sunscreen products in the future.

  17. Source Attribution of Light-absorbing Aerosols in Arctic Snow (Invited)

    NASA Astrophysics Data System (ADS)

    Hegg, D.; Warren, S. G.; Grenfell, T. C.; Doherty, S. J.; Larson, T. V.; Clarke, A. D.

    2010-12-01

    Light-absorbing aerosols (LAA) deposited on the arctic snow pack, in particular black carbon (BC), contribute appreciably to the arctic radiation budget and their reduction has been suggested as a means to attenuate warming in the arctic. Effective prediction and mitigation of Arctic snow LAA requires that the sources of the LAA be elucidated. To this end, receptor modeling in the form of Positive Matrix Factorization (PMF) has been exercised on a data set of chemical concentrations in snow of various species (including inorganic and organic acids, carbohydrates and selected other organics as well as LAA) derived from an extensive set of snow samples from locations in Russia (including Siberia), Canada, Greenland, the Arctic Ocean and Svalbard. The data were obtained in three distinct periods: spring of 2007, spring of 2008, and spring of 2009. Data from each period were analyzed separately (note that the Svalbard data were analyzed only recently and were not included in the published 2007 analysis). Aerosol light absorption was determined spectrophotometrically at multiple wavelengths on filters through which melted snow was filtered. Based on the Angstrom exponent of the light absorption, partitioning of the absorption between BC and other LAA species was estimated. Statistics of the LAA concentrations for the Arctic as a whole and the geographic distribution of BC and other LAA species are presented. PMF analysis of the filtrate and filters from the 2007 data set from western Siberia, the Canadian lower arctic and Greenland revealed four factors or sources: two distinct biomass burning sources, a pollution source and a marine source. The first three of these were responsible for essentially all of the black carbon, with the two biomass sources together accounting for > 90% of the black carbon. Geographically, the biomass sources were dominant for all regions except the Arctic Ocean near the North Pole. For the 2008 and 2009 data sets, from eastern Siberia and

  18. Upper-Room Ultraviolet Light and Negative Air Ionization to Prevent Tuberculosis Transmission

    PubMed Central

    Escombe, A. Roderick; Moore, David A. J; Gilman, Robert H; Navincopa, Marcos; Ticona, Eduardo; Mitchell, Bailey; Noakes, Catherine; Martínez, Carlos; Sheen, Patricia; Ramirez, Rocio; Quino, Willi; Gonzalez, Armando; Friedland, Jon S; Evans, Carlton A

    2009-01-01

    Background Institutional tuberculosis (TB) transmission is an important public health problem highlighted by the HIV/AIDS pandemic and the emergence of multidrug- and extensively drug-resistant TB. Effective TB infection control measures are urgently needed. We evaluated the efficacy of upper-room ultraviolet (UV) lights and negative air ionization for preventing airborne TB transmission using a guinea pig air-sampling model to measure the TB infectiousness of ward air. Methods and Findings For 535 consecutive days, exhaust air from an HIV-TB ward in Lima, Perú, was passed through three guinea pig air-sampling enclosures each housing approximately 150 guinea pigs, using a 2-d cycle. On UV-off days, ward air passed in parallel through a control animal enclosure and a similar enclosure containing negative ionizers. On UV-on days, UV lights and mixing fans were turned on in the ward, and a third animal enclosure alone received ward air. TB infection in guinea pigs was defined by monthly tuberculin skin tests. All guinea pigs underwent autopsy to test for TB disease, defined by characteristic autopsy changes or by the culture of Mycobacterium tuberculosis from organs. 35% (106/304) of guinea pigs in the control group developed TB infection, and this was reduced to 14% (43/303) by ionizers, and to 9.5% (29/307) by UV lights (both p < 0.0001 compared with the control group). TB disease was confirmed in 8.6% (26/304) of control group animals, and this was reduced to 4.3% (13/303) by ionizers, and to 3.6% (11/307) by UV lights (both p < 0.03 compared with the control group). Time-to-event analysis demonstrated that TB infection was prevented by ionizers (log-rank 27; p < 0.0001) and by UV lights (log-rank 46; p < 0.0001). Time-to-event analysis also demonstrated that TB disease was prevented by ionizers (log-rank 3.7; p = 0.055) and by UV lights (log-rank 5.4; p = 0.02). An alternative analysis using an airborne infection model demonstrated that ionizers prevented 60% of

  19. Ultra-broadband Tunable Resonant Light Trapping in a Two-dimensional Randomly Microstructured Plasmonic-photonic Absorber.

    PubMed

    Liu, Zhengqi; Liu, Long; Lu, Haiyang; Zhan, Peng; Du, Wei; Wan, Mingjie; Wang, Zhenlin

    2017-03-03

    Recently, techniques involving random patterns have made it possible to control the light trapping of microstructures over broad spectral and angular ranges, which provides a powerful approach for photon management in energy efficiency technologies. Here, we demonstrate a simple method to create a wideband near-unity light absorber by introducing a dense and random pattern of metal-capped monodispersed dielectric microspheres onto an opaque metal film; the absorber works due to the excitation of multiple optical and plasmonic resonant modes. To further expand the absorption bandwidth, two different-sized metal-capped dielectric microspheres were integrated into a densely packed monolayer on a metal back-reflector. This proposed ultra-broadband plasmonic-photonic super absorber demonstrates desirable optical trapping in dielectric region and slight dispersion over a large incident angle range. Without any effort to strictly control the spatial arrangement of the resonant elements, our absorber, which is based on a simple self-assembly process, has the critical merits of high reproducibility and scalability and represents a viable strategy for efficient energy technologies.

  20. Ultra-broadband Tunable Resonant Light Trapping in a Two-dimensional Randomly Microstructured Plasmonic-photonic Absorber

    PubMed Central

    Liu, Zhengqi; Liu, Long; Lu, Haiyang; Zhan, Peng; Du, Wei; Wan, Mingjie; Wang, Zhenlin

    2017-01-01

    Recently, techniques involving random patterns have made it possible to control the light trapping of microstructures over broad spectral and angular ranges, which provides a powerful approach for photon management in energy efficiency technologies. Here, we demonstrate a simple method to create a wideband near-unity light absorber by introducing a dense and random pattern of metal-capped monodispersed dielectric microspheres onto an opaque metal film; the absorber works due to the excitation of multiple optical and plasmonic resonant modes. To further expand the absorption bandwidth, two different-sized metal-capped dielectric microspheres were integrated into a densely packed monolayer on a metal back-reflector. This proposed ultra-broadband plasmonic-photonic super absorber demonstrates desirable optical trapping in dielectric region and slight dispersion over a large incident angle range. Without any effort to strictly control the spatial arrangement of the resonant elements, our absorber, which is based on a simple self-assembly process, has the critical merits of high reproducibility and scalability and represents a viable strategy for efficient energy technologies. PMID:28256599

  1. Ultra-broadband Tunable Resonant Light Trapping in a Two-dimensional Randomly Microstructured Plasmonic-photonic Absorber

    NASA Astrophysics Data System (ADS)

    Liu, Zhengqi; Liu, Long; Lu, Haiyang; Zhan, Peng; Du, Wei; Wan, Mingjie; Wang, Zhenlin

    2017-03-01

    Recently, techniques involving random patterns have made it possible to control the light trapping of microstructures over broad spectral and angular ranges, which provides a powerful approach for photon management in energy efficiency technologies. Here, we demonstrate a simple method to create a wideband near-unity light absorber by introducing a dense and random pattern of metal-capped monodispersed dielectric microspheres onto an opaque metal film; the absorber works due to the excitation of multiple optical and plasmonic resonant modes. To further expand the absorption bandwidth, two different-sized metal-capped dielectric microspheres were integrated into a densely packed monolayer on a metal back-reflector. This proposed ultra-broadband plasmonic-photonic super absorber demonstrates desirable optical trapping in dielectric region and slight dispersion over a large incident angle range. Without any effort to strictly control the spatial arrangement of the resonant elements, our absorber, which is based on a simple self-assembly process, has the critical merits of high reproducibility and scalability and represents a viable strategy for efficient energy technologies.

  2. 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.

  3. Photoprotection of human dermal fibroblasts against ultraviolet light by antioxidant combinations present in tomato.

    PubMed

    Fernández-García, Elisabet

    2014-02-01

    In the current study, we evaluated and compared, for the first time in a cell model, the effect of lycopene alone or in association with various antioxidants present in tomato such as α-tocopherol or naringenin, on their capacity to protect against oxidative stress generated in human dermal fibroblasts (hdf) exposed to ultraviolet-A (UVA) light. UVA irradiation of hdf led to a reduced cell viability in a dose dependent manner. Similar effects were observed when cells were exposed to lycopene. This reduction was suppressed in the presence of naringenin but not with α-tocopherol. Reactive oxygen species production was strongly induced by UVA irradiation. Only co-incubation with naringenin (highest level) was able to inhibit this effect. The combination of lycopene : naringenin further increased the stability of the carotenoid. Heme-oxygenase 1 (HO-1) expression was induced by UVA irradiation but none of the antioxidants inhibited this effect at the concentrations used in the study. Indeed, lycopene (1 μM) led to a further 2.5-fold rise in the UVA-induced HO-1 expression. However, this effect was suppressed by concomitant addition of naringenin. In our study, naringenin prevents oxidative degradation of lycopene. These results strengthen the hypothesis that combinations of dietary antioxidants present in tomato other than lycopene alone could play a role in the health effects of tomato as evidenced by epidemiological studies.

  4. The desmosomal protein Desmoglein 1 aids recovery of epidermal differentiation after acute ultraviolet light exposure

    PubMed Central

    Johnson, Jodi L.; Koetsier, Jennifer L.; Sirico, Anna; Agidi, Ada T.; Antonini, Dario; Missero, Caterina; Green, Kathleen J.

    2014-01-01

    Epidermal structure is damaged by exposure to ultraviolet (UV) light but the molecular mechanisms governing structural repair are largely unknown. UVB (290-320 nm wavelengths) exposure prior to induction of differentiation reduced expression of differentiation-associated proteins, including Desmoglein 1 (Dsg1), Desmocollin 1 (Dsc1) and Keratins 1 and 10 (K1/K10) in a dose-dependent manner in normal human epidermal keratinocytes (NHEKs). The UVB- induced reduction in both Dsg1 transcript and protein was associated with reduced binding of the p63 transcription factor to previously unreported enhancer regulatory regions of the Dsg1 gene. Since Dsg1 promotes epidermal differentiation in addition to participating in cell-cell adhesion, the role of Dsg1 in aiding differentiation after UVB damage was tested. Compared to controls, depleting Dsg1 via shRNA resulted in further reduction of Dsc1 and K1/K10 expression in monolayer NHEK cultures and in abnormal epidermal architecture in organotypic skin models recovering from UVB exposure. Ectopic expression of Dsg1 in keratinocyte monolayers rescued the UVB-induced differentiation defect. Treatment of UVB-exposed monolayer or organotypic cultures with Trichostatin A, a histone deacetylase inhibitor, partially restored differentiation marker expression, suggesting a potential therapeutic strategy for reversing UV-induced impairment of epidermal differentiation after acute sun exposure. PMID:24594668

  5. Effects of ultraviolet light disinfection on tetracycline-resistant bacteria in wastewater effluents.

    PubMed

    Childress, H; Sullivan, B; Kaur, J; Karthikeyan, R

    2014-09-01

    The ubiquitous use of antibiotics has led to an increasing number of antibiotic-resistant bacterial strains, including strains that are multidrug-resistant, pathogenic, or both. There is also evidence to suggest that antibiotic resistance genes (ARGs) spread to the environment, humans, and animals through wastewater effluents. The overall objective of this study was to investigate the effect of ultraviolet (UV) light disinfection on antibiotic-resistant bacteria. Wastewater effluent samples from a wastewater treatment plant (WWTP) in Texas were evaluated for differences in tetracycline-resistant bacteria before and after UV treatment. The effects of photoreactivation or dark repair on the reactivation of bacteria present in WWTP effluent after UV disinfection were also examined. Culture-based methods were used to characterize viable heterotrophic, tetracycline-resistant heterotrophic, Escherichia coli, and tetracycline-resistant E. coli bacteria present before and after UV treatment. UV disinfection was found to be as effective at reducing concentrations of resistant heterotrophs and E. coli, as it was at reducing total bacterial concentrations. The lowest survival ratio following UV disinfection was observed in tetracycline-resistant E. coli showing particular susceptibility to UV treatment. Photoreactivation and dark repair rates were found to be comparable to each other for all bacterial populations.

  6. Radiosensitization of human breast cancer cells to ultraviolet light by 5-fluorouracil

    PubMed Central

    SASAKI, KAZUHITO; TSUNO, NELSON H.; SUNAMI, EIJI; KAWAI, KAZUSHIGE; SHUNO, YASUTAKA; HONGO, KUMIKO; HIYOSHI, MASAYA; KANEKO, MANABU; MURONO, KOJI; TADA, NORIKO; NIREI, TAKAKO; KITAYAMA, JOJI; TAKAHASHI, KOKI; NAGAWA, HIROKAZU

    2011-01-01

    Ultraviolet light B (UVB) phototherapy is widely used to treat dermatological diseases and therefore may be a potential optional strategy in the treatment of a skin lesion infiltrated by a malignant tumor. Currently, little is known regarding the effect of UVB phototherapy on human breast cancer cells. The present study aimed to investigate the effect of UVB phototherapy, as well as the potential effect of 5-fluorouracil (5-FU), the first-line anticancer drug for breast cancer, on radiosensitizing MCF-7 human breast cancer cells, in an attempt to develop new therapeutic strategies for the treatment of locoregional recurrence of breast cancer. MCF-7 cells were incubated in the presence of 5-FU for 48 h, and UVB irradiation at 750 mJ/cm2 was administered in the midterm of 5-FU treatment. The viability of MCF-7 cells was analyzed by the trypan blue staining method. Apoptosis was quantified by flow cytometry and Hoechst 33258 staining. The cell cycle was evaluated by flow cytometry after the staining of cells with propidium iodide. The combination treatment of 5-FU and UVB resulted in a strong potentiation of the inhibitory effect of MCF-7 cell growth, dependent on the intra-S phase cell cycle arrest and induction of apoptosis, when compared to treatment with 5-FU or UVB alone. In conclusion, 5-FU sensitized human breast cancer cells to UVB phototherapy, and this combination therapy is an effective and promising strategy for the treatment of breast cancer, particularly for locoregional recurrence. PMID:22866105

  7. Activation of tat-defective human immunodeficiency virus by ultraviolet light

    SciTech Connect

    Sadaie, M.R.; Tschachler, E.; Valerie, K.; Rosenberg, M.; Felber, B.K.; Pavlakis, G.N.; Klotman, M.E.; Wong-Staal, F. )

    1990-05-01

    Ultraviolet light (UV) is known to cause activation of gene expression from the human immunodeficiency virus type 1 (HIV-1) promoter. To address the question of whether tat-defective HIV-1 provirus could be rescued by UV irradiation we examined its effect on HeLa cells containing integrated proviruses with tat mutations. Exposure of these cells to an optimal dose of UV resulted in the production of infectious viruses. The degree of UV activation and reversion to infectious virus appeared to depend on the nature of the original tat mutation. Two of the mutants required cocultivation with tat-expressing cells to fully generate replication competent viruses, while a third mutant required only cocultivation with H9 cells. Sequencing of cDNA from cells infected with this last mutant demonstrated that the parental mutant sequence was retained and that genotypic revertants to the wild-type as well as new mutant sequences were generated. These results suggest that tat-defective HIV-1 provirus can be activated by UV and can subsequently revert to wild-type virus. This study raises the possibility that UV exposure of immune cells in the skin plays a role in the activation of defective HIV-1 in vivo.

  8. Vertically aligned boron nitride nanosheets: chemical vapor synthesis, ultraviolet light emission, and superhydrophobicity.

    PubMed

    Yu, Jie; Qin, Li; Hao, Yufeng; Kuang, Shengyong; Bai, Xuedong; Chong, Yat-Ming; Zhang, Wenjun; Wang, Enge

    2010-01-26

    Boron nitride (BN) is a promising semiconductor with a wide band gap ( approximately 6 eV). Here, we report the synthesis of vertically aligned BN nanosheets (BNNSs) on silicon substrates by microwave plasma chemical vapor deposition from a gas mixture of BF(3)-N(2)-H(2). The size, shape, thickness, density, and alignment of the BNNSs were well-controlled by appropriately changing the growth conditions. With changing the gas flow rates of BF(3) and H(2) as well as their ratio, the BNNSs evolve from three-dimensional with branches to two-dimensional with smooth surface and their thickness changes from 20 to below 5 nm. The growth of the BNNSs rather than uniform granular films is attributed to the particular chemical properties of the gas system, mainly the strong etching effect of fluorine. The alignment of the BNNSs is possibly induced by the electrical field generated in plasma sheath. Strong UV light emission with a broad band ranging from 200 to 400 nm and superhydrophobicity with contact angles over 150 degrees were obtained for the vertically aligned BNNSs. The present BNNSs possess the properties complementary to carbon nanosheets such as intrinsically semiconducting, high temperature stability, and high chemical inertness and may find applications in ultraviolet nanoelectronics, catalyst supports, electron field emission, and self-cleaning coatings, etc., especially those working at high temperature and in harsh environments.

  9. Gold nanoparticles formed directly on a membrane by ultraviolet light irradiation

    SciTech Connect

    Qian, Hui Chen, Jian; Shen, Wei-Zheng; Kawasaki, Masahiro; Egerton, Ray F.

    2015-06-08

    There have been numerous research efforts directed towards the synthesis of gold (Au) nanoparticles (NPs) and the understanding of their formation, so that their size, shape, and stability can be well controlled for desired applications. Here, we report a dry photo-reduced method of Au NP formation directly on a membrane, such as a carbon thin film or a quartz slide. The evolution of Au NP formation was revealed by ex-situ experiments in an aberration-corrected scanning transmission electron microscope. The membranes were immersed in Au{sup 3+} solution before being taken out and quickly dried in ambient air at room temperature, then irradiated with ultraviolet (UV) light with wavelengths of 189 nm and 254 nm in a low-pressure chamber. The results show that Au{sup 3+} ions and ion clusters self-assembled on the membrane surface before UV irradiation and that solid Au NPs with sizes of 3 nm–12 nm were formed after UV irradiation. Annealing at 40 °C for about 30 min helped to further stabilize the nanoparticles. The Au NPs were uniform and well dispersed, and should find applications in the electron microscopy field, for example.

  10. CITIUS: An infrared-extreme ultraviolet light source for fundamental and applied ultrafast science

    SciTech Connect

    Grazioli, C.; Gauthier, D.; Ivanov, R.; De Ninno, G.; Callegari, C.; Spezzani, C.; Ciavardini, A.; Coreno, M.; Frassetto, F.; Miotti, P.; Poletto, L.; Golob, D.; Kivimäki, A.; Mahieu, B.; Bučar, B.; Merhar, M.; Polo, E.; Ressel, B.

    2014-02-15

    We present the main features of CITIUS, a new light source for ultrafast science, generating tunable, intense, femtosecond pulses in the spectral range from infrared to extreme ultraviolet (XUV). The XUV pulses (about 10{sup 5}-10{sup 8} photons/pulse in the range 14-80 eV) are produced by laser-induced high-order harmonic generation in gas. This radiation is monochromatized by a time-preserving monochromator, also allowing one to work with high-resolution bandwidth selection. The tunable IR-UV pulses (10{sup 12}-10{sup 15} photons/pulse in the range 0.4-5.6 eV) are generated by an optical parametric amplifier, which is driven by a fraction of the same laser pulse that generates high order harmonics. The IR-UV and XUV pulses follow different optical paths and are eventually recombined on the sample for pump-probe experiments. We also present the results of two pump-probe experiments: with the first one, we fully characterized the temporal duration of harmonic pulses in the time-preserving configuration; with the second one, we demonstrated the possibility of using CITIUS for selective investigation of the ultra-fast dynamics of different elements in a magnetic compound.

  11. CITIUS: an infrared-extreme ultraviolet light source for fundamental and applied ultrafast science.

    PubMed

    Grazioli, C; Callegari, C; Ciavardini, A; Coreno, M; Frassetto, F; Gauthier, D; Golob, D; Ivanov, R; Kivimäki, A; Mahieu, B; Bučar, B; Merhar, M; Miotti, P; Poletto, L; Polo, E; Ressel, B; Spezzani, C; De Ninno, G

    2014-02-01

    We present the main features of CITIUS, a new light source for ultrafast science, generating tunable, intense, femtosecond pulses in the spectral range from infrared to extreme ultraviolet (XUV). The XUV pulses (about 10(5)-10(8) photons/pulse in the range 14-80 eV) are produced by laser-induced high-order harmonic generation in gas. This radiation is monochromatized by a time-preserving monochromator, also allowing one to work with high-resolution bandwidth selection. The tunable IR-UV pulses (10(12)-10(15) photons/pulse in the range 0.4-5.6 eV) are generated by an optical parametric amplifier, which is driven by a fraction of the same laser pulse that generates high order harmonics. The IR-UV and XUV pulses follow different optical paths and are eventually recombined on the sample for pump-probe experiments. We also present the results of two pump-probe experiments: with the first one, we fully characterized the temporal duration of harmonic pulses in the time-preserving configuration; with the second one, we demonstrated the possibility of using CITIUS for selective investigation of the ultra-fast dynamics of different elements in a magnetic compound.

  12. Treatment of psoriasis with oral psoralens and longwave ultraviolet light. Therapeutic results and cytogenetic hazards.

    PubMed

    Swanbeck, G; Thyresson-Hök, M; Bredberg, A; Lambert, B

    1975-01-01

    The purpose of the present investigation was to study the usefulness of oral treatment of psoriasis with psoralens and longwave ultraviolet light and the possible cytogenetic hazards of this therapy. 8-methoxypsoralen (8-MOP) in doses between 15 and 60 mg orally followed 2 hours later by UVA irradiation of one side of the body gave a healing of the irradiated side in 24 of 40 cases and an improvment in another 11 cases while only one case healed on the side of body that was not irradiated. The most common undesired side effect was pruritus on the irradiated side of the body. The cytogenetic study showed that 8-MOP and UVA treatment of lymphocytes in vitro gives rise to chromosomal aberrations. In a combined in vivo-in vitro study where the lymphocytes had been isolated from a patient 2 hours after intake of 60-80 mg 8-MOP and then irradiated with therapeutic UVA doses, a significant increase in chromosomal aberrations was found. When chromosome analyses were made on the patients whilst the 8-MOP treatment was temporarily withdrawn and when the lymphocytes were not irradiated in vitro, no increased frequency of chromosomal abberations was found on comparison with a group of psoriatic patients receiving dithranol therapy.

  13. Infrared-laser-assisted photoionization of helium by coherent extreme ultraviolet light

    SciTech Connect

    Tong Xiaomin; Toshima, Nobuyuki

    2010-04-15

    We investigate the infrared (IR)-laser-assisted photoionization of He by a coherent extreme ultraviolet (euv) light solving the time-dependent Schroedinger equation. A combined field of the 13th and 15th harmonics created from the same IR laser source is used to ionize He atoms coherently. We show that the ionization probabilities oscillate as a function of the time delay between the IR and the euv pulses. On the other hand, the oscillation amplitude increases as the IR intensity increases, reaches a maximum when the IR intensity is around 6x10{sup 12} W/cm{sup 2}, and then decreases as the IR intensity increases further. Decomposing the ionization probabilities by the 13th and 15th harmonics, we illustrate that the oscillation amplitude is small for a lower IR laser intensity due to the fact that the transition strength by the 13th harmonic is much smaller than the one by the 15th harmonic. When the IR intensity increases further above 6x10{sup 12} W/cm{sup 2}, the transition strength by the 13th harmonic becomes larger than the one by the 15th harmonic and the oscillation amplitude is reduced again. By tuning the relative field strengths of the 13th and 15th harmonics or the IR intensity, we can control the oscillation amplitude.

  14. Simultaneous irradiation with different wavelengths of ultraviolet light has synergistic bactericidal effect on Vibrio parahaemolyticus.

    PubMed

    Nakahashi, Mutsumi; Mawatari, Kazuaki; Hirata, Akiko; Maetani, Miki; Shimohata, Takaaki; Uebanso, Takashi; Hamada, Yasuhiro; Akutagawa, Masatake; Kinouchi, Yousuke; Takahashi, Akira

    2014-01-01

    Ultraviolet (UV) irradiation is an increasingly used method of water disinfection. UV rays can be classified by wavelength into UVA (320-400 nm), UVB (280-320 nm), and UVC (<280 nm). We previously developed UVA sterilization equipment with a UVA light-emitting diode (LED). The aim of this study was to establish a new water disinfection procedure using the combined irradiation of the UVA-LED and another UV wavelength. An oxidative DNA product, 8-hydroxy-2'-deoxyguanosine (8-OHdG), increased after irradiation by UVA-LED alone, and the level of cyclobutane pyrimidine dimers (CPDs) was increased by UVC alone in Vibrio parahaemolyticus. Although sequential irradiation of UVA-LED and UVC-induced additional bactericidal effects, simultaneous irradiation with UVA-LED and UVC-induced bactericidal synergistic effects. The 8-OHdG and CPDs production showed no differences between sequential and simultaneous irradiation. Interestingly, the recovery of CPDs was delayed by simultaneous irradiation. The synergistic effect was absent in SOS response-deficient mutants, such as the recA and lexA strains. Because recA- and lexA-mediated SOS responses have crucial roles in a DNA repair pathway, the synergistic bactericidal effect produced by the simultaneous irradiation could depend on the suppression of the CPDs repair. The simultaneous irradiation of UVA-LED and UVC is a candidate new procedure for effective water disinfection.

  15. Ultraviolet light and laser irradiation enhances the antibacterial activity of glucosamine-functionalized gold nanoparticles

    PubMed Central

    Govindaraju, Saravanan; Ramasamy, Mohankandhasamy; Baskaran, Rengarajan; Ahn, Sang Jung; Yun, Kyusik

    2015-01-01

    Here we report a novel method for the synthesis of glucosamine-functionalized gold nanoparticles (GlcN-AuNPs) using biocompatible and biodegradable glucosamine for antibacterial activity. GlcN-AuNPs were prepared using different concentrations of glucosamine. The synthesized AuNPs were characterized for surface plasmon resonance, surface morphology, fluorescence spectroscopy, and antibacterial activity. The minimum inhibitory concentrations (MICs) of the AuNPs, GlcN-AuNPs, and GlcN-AuNPs when irradiated by ultraviolet light and laser were investigated and compared with the MIC of standard kanamycin using Escherichia coli by the microdilution method. Laser-irradiated GlcN-AuNPs exhibited significant bactericidal activity against E. coli. Flow cytometry and fluorescence microscopic analysis supported the cell death mechanism in the presence of GlcN-AuNP-treated bacteria. Further, morphological changes in E. coli after laser treatment were investigated using atomic force microscopy and transmission electron microscopy. The overall results of this study suggest that the prepared nanoparticles have potential as a potent antibacterial agent for the treatment of a wide range of disease-causing bacteria. PMID:26345521

  16. Fabrication of an optical lens array using ultraviolet light and ultrasonication.

    PubMed

    Taniguchi, Satoki; Koyama, Daisuke; Nakamura, Kentaro; Matsukawa, Mami

    2015-04-01

    A technique to form an optical lens array using an ultraviolet (UV)-curable resin and ultrasound was investigated. A UV-curable gel film was formed on a glass plate having four lead zirconate titanate (PZT) transducers. Excitation of the transducers generated a lattice flexural vibration mode on the glass plate. The acoustic radiation force acted to deform the surface of the gel film, so that a lens array could be fabricated on the gel film. The lens array was exposed to UV light under ultrasonication to cure the UV-curable film. The quality factor of the transducer resonance was decreased upon curing of the resin film because the cured resin dampened the vibration of the plate. The acoustic characteristics of the UV-curable gel film were measured by using an ultrasound pulse technique at the MHz range. The sound speed of the gel increased from 987 to 1006 m/s (increase of 1.9%) as the UV exposure time increased. The attenuation coefficient also increased and the larger attenuation of the resin caused the lens array to have a lower quality factor.

  17. Photooxidation of plasma polymerized polydimethylsiloxane film by 172 nm vacuum ultraviolet light irradiation in dilute oxygen

    SciTech Connect

    Ichikawa, S.

    2006-08-01

    Plasma polymerized polydimethylsiloxane films irradiated under different partial pressures of oxygen with a 172 nm vacuum ultraviolet light were investigated in order to clarify the roles of molecular oxygen and photons in photooxidation. The thickness, densities, surface roughness, elemental compositions, and molecular structures of the irradiated and unirradiated films were examined by using glazing incidence x-ray reflectivity, Rutherford backscattering, infrared, and x-ray absorption (XAS) spectroscopies. Photooxidation is hardly promoted by irradiation in a high vacuum of 1x10{sup -4} Pa, though photodesorption of the methyl group and formation of Si-H bonds were observed. Silica films thicker than 140 nm were formed at room temperature by irradiating them in low pressure oxygen gases. The degree of oxidation was smaller for the oxygen pressure of 10 kPa than for 83 Pa. Si K-edge XAS was performed to clarify the change of coordination environment of silicon by photooxidation in dilute oxygen flow containing less than 5 ppm of molecular oxygen.

  18. Differences in Median Ultraviolet Light Transmissions of Serial Homeopathic Dilutions of Copper Sulfate, Hypericum perforatum, and Sulfur.

    PubMed

    Klein, Sabine D; Sandig, Annegret; Baumgartner, Stephan; Wolf, Ursula

    2013-01-01

    Homeopathic remedies are produced by potentising, that is, the serial logarithmic dilution and succussion of a mother tincture. Techniques like ultraviolet spectroscopy, nuclear magnetic resonance, calorimetry, or thermoluminescence have been used to investigate their physical properties. In this study, homeopathic centesimal (c) potencies (6c to 30c) of copper sulfate, Hypericum perforatum, and sulfur as well as succussed water controls were prepared. Samples of these preparations were exposed to external physical factors like heat, pressure, ultraviolet radiation, or electromagnetic fields to mimic possible everyday storage conditions. The median transmissions from 190 nm to 340 nm and 220 nm to 340 nm were determined by ultraviolet light spectroscopy on five measurement days distributed over several months. Transmissions of controls and potencies of sulfur differed significantly on two of five measurement days and after exposure to physical factors. Transmissions of potencies exposed to ultraviolet light and unexposed potencies of copper sulfate and Hypericum perforatum differed significantly. Potency levels 6c to 30c were also compared, and wavelike patterns of higher and lower transmissions were found. The Kruskal-Wallis test yielded significant differences for the potency levels of all three substances. Aiming at understanding the physical properties of homeopathic preparations, this study confirmed and expanded the findings of previous studies.

  19. Light Scattering by Coated Sphere Immersed in Absorbing Medium: A Comparison between the FDTD and Analytic Solutions

    NASA Technical Reports Server (NTRS)

    Sun, W.; Loeb, N. G.; Fu, Q.

    2004-01-01

    A recently developed finite-difference time domain scheme is examined using the exact analytic solutions for light scattering by a coated sphere immersed in an absorbing medium. The relative differences are less than 1% in the extinction, scattering, and absorption efficiencies and less than 5% in the scattering phase functions. The definition of apparent single-scattering properties is also discussed. (C) 2003 Elsevier Ltd. All rights reserved.

  20. Bandgap Tunability in Sb-Alloyed BiVO₄ Quaternary Oxides as Visible Light Absorbers for Solar Fuel Applications.

    PubMed

    Loiudice, Anna; Ma, Jie; Drisdell, Walter S; Mattox, Tracy M; Cooper, Jason K; Thao, Timothy; Giannini, Cinzia; Yano, Junko; Wang, Lin-Wang; Sharp, Ian D; Buonsanti, Raffaella

    2015-11-01

    The challenge of fine compositional tuning and microstructure control in complex oxides is overcome by developing a general two-step synthetic approach. Antimony-alloyed bismuth vanadate, which is identified as a novel light absorber for solar fuel applications, is prepared in a wide compositional range. The bandgap of this quaternary oxide linearly decreases with the Sb content, in agreement with first-principles calculations.

  1. Enzyme plus light therapy to repair DNA damage in ultraviolet-B-irradiated human skin

    PubMed Central

    Stege, Helger; Roza, Len; Vink, Arie A.; Grewe, Markus; Ruzicka, Thomas; Grether-Beck, Susanne; Krutmann, Jean

    2000-01-01

    Ultraviolet-B (UVB) (290–320 nm) radiation-induced cyclobutane pyrimidine dimers within the DNA of epidermal cells are detrimental to human health by causing mutations and immunosuppressive effects that presumably contribute to photocarcinogenesis. Conventional photoprotection by sunscreens is exclusively prophylactic in nature and of no value once DNA damage has occurred. In this paper, we have therefore assessed whether it is possible to repair UVB radiation-induced DNA damage through topical application of the DNA-repair enzyme photolyase, derived from Anacystis nidulans, that specifically converts cyclobutane dimers into their original DNA structure after exposure to photoreactivating light. When a dose of UVB radiation sufficient to induce erythema was administered to the skin of healthy subjects, significant numbers of dimers were formed within epidermal cells. Topical application of photolyase-containing liposomes to UVB-irradiated skin and subsequent exposure to photoreactivating light decreased the number of UVB radiation-induced dimers by 40–45%. No reduction was observed if the liposomes were not filled with photolyase or if photoreactivating exposure preceded the application of filled liposomes. The UVB dose administered resulted in suppression of intercellular adhesion molecule-1 (ICAM-1), a molecule required for immunity and inflammatory events in the epidermis. In addition, in subjects hypersensitive to nickel sulfate, elicitation of the hypersensitivity reaction in irradiated skin areas was prevented. Photolyase-induced dimer repair completely prevented these UVB radiation-induced immunosuppressive effects as well as erythema and sunburn-cell formation. These studies demonstrate that topical application of photolyase is effective in dimer reversal and thereby leads to immunoprotection. PMID:10660687

  2. Lateral epitaxial overgrowth of aluminum nitride and near ultraviolet LEDs for white lighting applications

    NASA Astrophysics Data System (ADS)

    Newman, Scott A.

    In recent years, substantial efforts have been made to develop deep ultraviolet AlGaN-based LEDs (200-280 nm) for specialized applications such as bio-detection and non-line-of-sight (NLOS) communications. One of several factors limiting the performance of these devices is the high threading dislocation (TD) density of ˜5x109 cm-2 that results from growing the required AlN base layer on either a SiC or sapphire substrate. Lateral epitaxial overgrowth (LEO) of AlN, the first topic of this dissertation, is a promising technology for growing low TD density AlN templates. Conventional LEO methods relying on selective area growth (SAG) have not been effective for AlxGa1-xN with x > 0.2, because of the high aluminum sticking coefficient for the mask materials and/or contamination of the film by the mask. Therefore, maskless AlN LEO was investigated using metal organic chemical vapor deposition (MOCVD) and hydride vapor phase epitaxy (HVPE). Cracked AlN films with TD densities of < 1x107 cm-2 in the wing regions were grown by HVPE on patterned 6H-SiC templates. Cracking was attributed to the unfavorable thermal expansion mismatch between AlN and 6H-SiC. Crack-free AlN films with TD densities of < 1x108 cm-2 in the wing regions were grown by HVPE on patterned sapphire templates. An MOCVD AlN LEO process relying on SAG over an in situ deposited SiNx nano-mask was also investigated. However, this process did not yield useful defect reduction. The second topic of this dissertation is 365-400 nm near-ultraviolet (NUV) LEDs for white lighting applications. Currently, cool white LEDs consisting of a blue GaN/InGaN LED and the YAG:Ce3+ yellow phosphor are available with 107 lm/W efficacy, but have have high correlated color temperatures (CCTs) of ˜5,500 K and poor color rendering indices (CRIs) of ˜75. The alternative approach of combining a NUV LED with suitable NUV-excitation phosphors (e.g., red, green, and blue phosphors) can theoretically allow for high CRI white lighting

  3. Electrochromic responses of carotenoid absorbance bands in purified light-harvesting complexes from Rhodobacter capsulatus reconstituted into liposomes.

    PubMed

    Goodwin, M G; Jackson, J B

    1993-09-13

    Light-Harvesting Complexes I and II (LHI and LHII) were extracted from chromatophores of Rhodobacter capsulatus, purified in Triton X-100 and reconstituted into phospholipid vesicles. Application of membrane potentials (K+ diffusion potentials) to LHII proteoliposomes led to absorbance changes in the carotenoid bands which were spectrally similar to those in chromatophores. These (electrochromic) absorbance changes were linear with the applied membrane potential between -107 mV and +105 mV. The data were consistent with the existence of two forms of carotenoid in LHII. One form, comprising 2/3 of the total and with a long wavelength absorbance maximum at 510 nm, was not significantly affected by membrane potential. The other component, comprising 1/3 of the total and with a long wavelength absorbance maximum at 516.5 nm, was shifted by approx. 1.6 nm to the red by a membrane potential of 105 mV. Reduction of the B800 bacteriochlorophyll in LHII with NaBH4 before reconstitution did not affect the absorbance spectrum of the carotenoids and it did not affect their response to applied membrane potentials in proteoliposomes. Although the electrochromically-sensitive carotenoids might be associated with B800, interactions with the bacteriochlorophyll are perhaps not the cause of the polarisation of the carotenoid that is responsible for the linearity of the response. The carotenoids in reconstituted LHI complexes were not detectably electrochromic. The electrochromic absorbance changes of carotenoids in LHII could be useful for membrane potential measurement in liposomes containing ion-translocating proteins.

  4. Light interaction in sapphire/MgF2/Al triple-layer omnidirectional reflectors in AlGaN-based near ultraviolet light-emitting diodes

    PubMed Central

    Lee, Keon Hwa; Moon, Yong-Tae; Song, June-O; Kwak, Joon Seop

    2015-01-01

    This study examined systematically the mechanism of light interaction in the sapphire/MgF2/Al triple-layer omnidirectional reflectors (ODR) and its effects on the light output power in near ultraviolet light emitting diodes (NUV-LEDs) with the ODR. The light output power of NUV-LEDs with the triple-layer ODR structure increased with decreasing surface roughness of the sapphire backside in the ODR. Theoretical modeling of the roughened surface suggests that the dependence of the reflectance of the triple-layer ODR structure on the surface roughness can be attributed mainly to light absorption by the Al nano-structures and the trapping of scattered light in the MgF2 layer. Furthermore, the ray tracing simulation based upon the theoretical modeling showed good agreement with the measured reflectance of the ODR structure in diffuse mode. PMID:26010378

  5. Removal of pollutant compounds from water supplies using ozone, ultraviolet light, and a counter, current packed column. Master's thesis

    SciTech Connect

    Kelly, E.L.

    1991-01-01

    Many water pollutants are determined to be carcinogenic and often appear in very low concentrations and still pose a health risk. Conventional water treatment processes cannot remove these contaminants and there is a great demand for the development of alternative removal technologies. The use of ozone and ultraviolet light in a counter current packed column could prove to be an effective treatment process to remove these contaminants.

  6. A 28-day repeated dose toxicity study of ultraviolet absorber 2-(2'-hydroxy-3',5'-di-tert-butylphenyl) benzotriazole in rats.

    PubMed

    Hirata-Koizumi, Mutsuko; Watari, Nobuaki; Mukai, Daisuke; Imai, Toshio; Hirose, Akihiko; Kamata, Eiichi; Ema, Makoto

    2007-01-01

    To examine the possible repeated-dose toxicity of an ultraviolet absorber, 2-(2'-hydroxy-3',5'-di-tert-butylphenyl)benzotriazole (HDBB), CD(SD)IGS rats were administered HDBB by gavage at a dose of 0 (vehicle: corn oil), 0.5, 2.5, 12.5, or 62.5 mg kg(-1) day(-1) for 28 days. At the completion of the administration period, a decrease in red blood cells, hemoglobin, and hematocrit was noted only in males at 2.5 mg/kg and more. Blood biochemical changes were noted at 0.5 mg/kg and more in males and at 62.5 mg/kg in females. Histopathologic changes were observed principally in the liver (vacuolar degeneration and hypertrophy of hepatocytes, bile duct proliferation, etc.) and in the heart (degeneration and hypertrophy of myocardium and cell infiltration). These changes were noted at 0.5 mg/kg and more in males and at 12.5 mg/kg and more in females. At higher doses, hypertrophy of tubular epithelium in the kidneys and diffuse follicular cell hyperplasia in the thyroids in both sexes and increased severity of basophilic tubules in the kidneys and extramedullary hematopoiesis in the spleen in males were also detected. After the 14-day recovery period, these changes mostly recovered in females but not in males. Based on these findings, no observed adverse effect level (NOAEL) was concluded to be less than 0.5 mg kg(-1) day(-1) in male rats and 2.5 mg kg(-1) day(-1) in female rats.

  7. Ultraviolet index: a light in atopic dermatitis and vitamin D research?*

    PubMed Central

    Mesquita, Kleyton de Carvalho; Igreja, Ana Carolina de Souza Machado; Costa, Izelda Maria Carvalho

    2016-01-01

    BACKGROUND: The role played by vitamin D in atopic dermatitis is controversial and has been the focus of many studies. The ultraviolet index has not been considered in this type of research. OBJECTIVES: The objectives of the study were to assess 25-hydroxy vitamin D [25(OH)D] serum level in atopic dermatitis patients and control group, to investigate the association between atopic dermatitis clinical severity (using the SCORing Atopic Dermatitis index - SCORAD) and 25(OH)D serum levels, and to evaluate the independent predictors, including Ultraviolet index, SCORAD and 25(OH)D. METHODS: We conducted a cross-sectional study of 106 atopic dermatitis patients. A control group was matched with a subsample of 54 participants with atopic dermatitis. SCORAD index, laboratory tests, and local Ultraviolet index were assessed. RESULTS: The atopic dermatitis patients had serum 25(OH)D levels and mean UVI significantly higher than the control group. Immunoglobulin E and Ultraviolet index were associated with the SCORAD index. Skin type, age and Ultraviolet index were independent predictors of 25(OH)D. CONCLUSIONS: Although statistically significant, the different levels of 25(OH)D between the paired groups may be attributed to the higher mean Ultraviolet index in atopic dermatitis patients. Since Ultraviolet index is an independent predictor of SCORAD index and of 25(OH)D level, it may work as a confounding factor in studies involving atopic dermatitis and 25(OH)D and must be considered in this kind of research. PMID:26982776

  8. Ultraviolet light protection by a sunscreen prevents interferon-driven skin inflammation in cutaneous lupus erythematosus.

    PubMed

    Zahn, Sabine; Graef, Medina; Patsinakidis, Nikolaos; Landmann, Aysche; Surber, Christian; Wenzel, Joerg; Kuhn, Annegret

    2014-07-01

    Irradiation with ultraviolet (UV) light is an important exacerbating factor in cutaneous lupus erythematosus (CLE) and induces various effects in the skin of patients with the disease, such as cell death and inflammation. Recently, we demonstrated the ability of a broad-spectrum sunscreen to prevent UV-induced damage both in patients with CLE and healthy controls (HCs). The aim of this study was to evaluate whether the UV-dependent activation of interferon (IFN)-driven inflammation in CLE can also be prevented by application of the sunscreen. In 20 patients with different subtypes of CLE and 10 HCs, defined areas on the upper back were treated with a broad-spectrum liposomal sunscreen 20 min prior to a combined standardized UVA/UVB irradiation. Immunohistological analyses using antibodies directed against MxA, CD11c, CD123 and CD68 were performed from skin biopsies taken from areas before UV irradiation as well as from sunscreen-treated and sunscreen-untreated areas 24 and 72 h after UV irradiation. The expression of MxA was completely prevented by the sunscreen applied prior to UV irradiation in CLE patients and HCs. Additionally, sunscreen protection significantly diminished the number of the CD11c- and CD123-positive dendritic cells, which are suggested to be a major source of type I/III IFNs, in UV-irradiated skin of patients with CLE. Moreover, the application of the sunscreen prevented the increase in CD68-positive macrophages in both groups 72 h after UV irradiation. The data of this study demonstrate that UV protection reduces lesional tissue damage and inhibits the typical IFN-driven inflammatory response in CLE.

  9. Physical Control of Spider Mites Using Ultraviolet-B With Light Reflection Sheets in Greenhouse Strawberries.

    PubMed

    Tanaka, Masaya; Yase, Junya; Aoki, Shinichi; Sakurai, Takafumi; Kanto, Takeshi; Osakabe, Masahiro

    2016-08-01

    Development of spider mite management technology other than chemical control is desired because of the serious development of acaricide resistance worldwide. Recent studies have evidenced the lethal effects of ultraviolet-B (UVB) radiation on spider mites. To develop the technology on how to use UVB irradiation for spider mite control, we tested whether UVB lamp-light reflection sheet (LRS) combinations suppressed the population size of Tetranychus urticae Koch on strawberry in a greenhouse from December to May (2012-2013, 2013-2014) in Japan. We designed four combinations of UVB lamps and LRSs: 1) neither UVB lamps nor LRSs (UV-LRS-); 2) a UVB lamp without an LRS (UV+LRS-; 2012-2013 only); 3) a UVB lamp and a mulch-type LRS (UV+LRSm); and 4) a UVB lamp and a wing-type LRS (UV+LRSw). The number of adult females peaked at 438.0 and 222.0 per plant in UV-LRS- of 2012-2013 and 2013-2014, respectively, and peaked at 191.6 females in UV+LRS- of 2012-2013. In contrast, the peak abundance was 20.9-98.0 females in UV+LRSm, and fewer than 15 females were noted in UV+LRSw over either experimental period. UVB irradiance on lower leaf surfaces was higher in UV+LRSm and UV+LRSw than UV-LRS- and UV+LRS-, and the mite densities were significantly correlated with UVB irradiance on lower leaf surfaces. Consequently, we conclude that the combinations of UVB lamp-LRS have an excellent capacity to control T. urticae on greenhouse strawberry, and that the LRS was an essential component in this technological approach.

  10. Differential roles of nitric oxide synthases in regulation of ultraviolet B light-induced apoptosis.

    PubMed

    Liu, Wei; Wu, Shiyong

    2010-11-01

    Ultraviolet B light (UVB) activates nitric oxide synthase(s) (NOSs) and nitric oxide (NO()) production, which plays a role in regulation of apoptosis. However, the role of NO() in UVB-induced apoptosis remains controversial. In this study, we analyzed expression and activation of constitutive NOSs (cNOSs) and their roles in UV-induced apoptosis of HaCaT keratinocytes. Our data showed that the expression of neuronal NOS (nNOS) was increased while endothelial NOS (eNOS) was uncoupled in the early phase (0-6 h) post-UVB. The expression of both cNOSs peaked at 12h post-UVB and NO() was transiently elevated with 30 min and then steadily rose from 6 to 18 h post-UVB. The expression of iNOS was detected at 6h post-UVB and then sturdily increased. Inhibition of cNOSs with L-NAME reduced the inducibility of NO(*) in the early and late phases of irradiation. Along with the eNOS uncoupling, an increased level of peroxynitrite (ONOO(-)) was detected in the early phase, but not in the late phase post-UVB. Inhibition of cNOSs reduced the production of ONOO(-) in the early time, but led to an increase of ONOO(-) in the late time after UVB-irradiation. The results indicate that cNOSs regulate NO()/ONOO(-) imbalance after UVB-irradiation. Our data suggested that the activation of cNOSs in the early phase post-UVB leads to NO()/ONOO(-) imbalance and promotes apoptosis via a caspase 3-independent pathway. The elevation of NO() in the late phase of UVB-irradiation is mainly produced by inducible NOS (iNOS). However, cNOSs also contribute to the NO() production and to maintain a higher NO()/ONOO(-) ratio, which reduces caspase 3 activity and protects cells from UVB-induced apoptosis.

  11. The roles of translation initiation regulation in ultraviolet light-induced apoptosis.

    PubMed

    Parker, Suzanne H; Parker, Todd A; George, Kimberly S; Wu, Shiyong

    2006-12-01

    Ultraviolet light (UV) inhibits translation initiation through activation of kinases that phosphorylate the alpha-subunit of eukaryotic initiation factor 2 (eIF2alpha). Two eIF2alpha kinases, PERK and GCN2, are known to phosphorylate the Serine-51 of eIF2alpha in response to UV-irradiation. In this report, we present evidence that phosphorylation of eIF2alpha plays a role in UV-induced apoptosis. Our data show that wild-type mouse embryo fibroblasts (MEF(s/s)) are less sensitive to UV-induced apoptosis than MEF(A/A) cells in which the phosphorylation site, Ser51, of eIF2alpha is replaced with a non-phosphorylatable Ala (Ser51Ala). PARP expression in MEF(A/A) cells is reduced without being cleaved after UV-irradiation. In contrast, PARP is cleaved without a significant decrease in parental PARP in MEF(S/S) cells after UV-irradiation. Our data also show that MEF(GCN2-/-) cells, in which GCN2 is knocked out, are more sensitive to UV-irradiation, agreeing with the observation from MEF(A/A) cells. However, MEF(PERK-/-) cells, in which PERK is knocked out, are less sensitive to UV-irradiation. In addition, MCF-7-PERKDeltaC cells, which are stably transfected with a kinase domain deleted mutant of PERK (PERKDeltaC), are more resistant to UV-induced apoptosis than parental MCF-7 cells. Overexpression of wild-type PERK sensitizes MCF-7 cells to UV-induced apoptosis without directly inducing cell death. These results suggest that the level of eIF2alpha phosphorylation impacts PARP expression upon UV-irradiation. The eIF2alpha kinases may mediate UV-induced apoptosis via an eIF2alpha dependent or independent signaling pathway.

  12. Secondary brown carbon - Formation of light-absorbing compounds in atmospheric particulates from selected dicarbonyls and amines

    NASA Astrophysics Data System (ADS)

    Kampf, Christopher; Filippi, Alexander; Hoffmann, Thorsten

    2015-04-01

    One of the main open questions regarding organic compounds in atmospheric chemistry today is related to the formation of optically-active compounds and the occurrence of so called brown carbon (Andreae and Gelencsér, 2006). While organic compounds in ambient fine particles for decades have been assumed to not absorb solar radiation, thus resulting in a net cooling effect on climate (IPCC, 2007), it is now generally accepted that a continuum of light-absorbing carbonaceous species is present in fine aerosols (Pöschl, 2003). In this study, light-absorbing compounds from reactions between dicarbonyl compounds, i.e., glyoxal, methylglyoxal, acetylacetone, 2,3-butanedione, 2,5-hexanedione, and glutaraldehyde, and amine species, i.e., ammonia and glycine, were investigated at atmospherically relevant concentrations in bulk solution experiments mimicking atmospheric particulates. Product analyses were performed using UV/Vis spectrophotometry and (ultra) high performance liquid chromatography coupled to diode array detection and ion trap mass spectrometry (HPLC-DAD-ESI-MS/MS), as well as ultra-high resolution (Orbitrap) mass spectrometry (UHPLC-ESI-HRMS/MS). We demonstrate that light-absorbing compounds are formed from a variety of atmospherically relevant dicarbonyls via particle phase reactions with amine nucleophiles. Single dicarbonyl and mixed dicarbonyl experiments were performed and products were analyzed. The reaction products are suggested to be cyclic nitrogen containing compounds such as imidazoles or dihydropyridines as well as open chain compounds resulting from aldol condensation reactions. Further, the reactive turnover was found to be higher at increasing pH values. The aforementioned processes may be of higher relevance in regions with high aerosol pH, e.g., resulting from high ammonia emissions as for example in northern India (Clarisse et al., 2009). References Andreae, M.O., and Gelencsér, A. (2006): Black carbon or brown carbon? The nature of light-absorbing

  13. Measurements of electron and proton heating temperatures from extreme-ultraviolet light images at 68 eV in petawatt laser experiments

    SciTech Connect

    Gu Peimin; Zhang, B.; Key, M. H.; Hatchett, S. P.; Barbee, T.; Freeman, R. R.; Akli, K.; Hey, D.; King, J. A.; Mackinnon, A. J.; Snavely, R. A.; Stephens, R. B.

    2006-11-15

    A 68 eV extreme-ultraviolet light imaging diagnostic measures short pulse isochoric heating by electrons and protons in petawatt laser experiments. Temperatures are deduced from the absolute intensities and comparison with modeling using a radiation hydrodynamics code.

  14. Formation of the thioester, N,S-diacetylcysteine, from acetaldehyde and N,N'-diacetylcystine in aqueous solution with ultraviolet light

    NASA Technical Reports Server (NTRS)

    Weber, A. L.

    1981-01-01

    The thioester, N,S-diacetylcysteine, is formed during the illumination of phosphate buffered (pH 7.0) aqueous solutions of acetaldehyde and N,N'-diacetylcystine with ultraviolet light. The yield of N,S-diacetylcysteine relative to N-acetylcysteine and unidentified products progressively increases as ultraviolet light below 239 nm, 253 nm and 281 nm is cut off with optical filters. When ultraviolet light below 320 nm is removed with an optical filter, there is no detectable reaction. Illumination of 0.025 M N,N'-diacetylcystine with 0.5 M and 1.0 M acetaldehyde with filtered ultraviolet light gives, respectively, 20% and 80% yields of N,S-diacetylcysteine. In the reaction with 1.0 M acetaldehyde, N-acetylcysteine forms early in the reaction and later decreases with its conversion to N,S-diacetylcysteine. The prebiotic significance of these reactions is discussed.

  15. Biological Effects of Sunlight, Ultraviolet Radiation, Visible Light, Infrared Radiation and Vitamin D for Health.

    PubMed

    Holick, Michael F

    2016-03-01

    Humans evolved in sunlight and had depended on sunlight for its life giving properties that was appreciated by our early ancestors. However, for more than 40 years the lay press and various medical and dermatology associations have denounced sun exposure because of its association with increased risk for skin cancer. The goal of this review is to put into perspective the many health benefits that have been associated with exposure to sunlight, ultraviolet A (UVA) ultraviolet B (UVB), visible and infrared radiation.

  16. All-angle negative refraction and active flat lensing of ultraviolet light.

    PubMed

    Xu, Ting; Agrawal, Amit; Abashin, Maxim; Chau, Kenneth J; Lezec, Henri J

    2013-05-23

    Decades ago, Veselago predicted that a material with simultaneously negative electric and magnetic polarization responses would yield a 'left-handed' medium in which light propagates with opposite phase and energy velocities--a condition described by a negative refractive index. He proposed that a flat slab of left-handed material possessing an isotropic refractive index of -1 could act like an imaging lens in free space. Left-handed materials do not occur naturally, and it has only recently become possible to achieve a left-handed response using metamaterials, that is, electromagnetic structures engineered on subwavelength scales to elicit tailored polarization responses. So far, left-handed responses have typically been implemented using resonant metamaterials composed of periodic arrays of unit cells containing inductive-capacitive resonators and conductive wires. Negative refractive indices that are isotropic in two or three dimensions at microwave frequencies have been achieved in resonant metamaterials with centimetre-scale features. Scaling the left-handed response to higher frequencies, such as infrared or visible, has been done by shrinking critical dimensions to submicrometre scales by means of top-down nanofabrication. This miniaturization has, however, so far been achieved at the cost of reduced unit-cell symmetry, yielding a refractive index that is negative along only one axis. Moreover, lithographic scaling limits have so far precluded the fabrication of resonant metamaterials with left-handed responses at frequencies beyond the visible. Here we report the experimental implementation of a bulk metamaterial with a left-handed response to ultraviolet light. The structure, based on stacked plasmonic waveguides, yields an omnidirectional left-handed response for transverse magnetic polarization characterized by a negative refractive index. By engineering the structure to have a refractive index close to -1 over a broad angular range, we achieve Veselago

  17. Dose-related effects of psoralen and ultraviolet light on the cell cycle of murine melanoma cells

    SciTech Connect

    Varga, J.M.; Wiesehahn, G.; Bartholomew, J.C.; Hearst, J.E.

    1982-06-01

    Cloudman (S91) murine melanoma cells were treated with 4'-hydroxymethyltrioxsalen (HMT), a bifunctional psoralen and exposed to long-wavelength (365 nm) ultraviolet light. DNA content of the cells stained with propidium iodide was measured by flow cytometry, and cell cycle phases were delineated from the DNA histograms by using a curve-fitting routine. Researchers found that HMT in combination with long-wavelength (365 nm) ultraviolet irradiation blocked melanoma cells in different phases of the cell cycle, depending on the dose of long-wavelength (365 nm) ultraviolet light and the concentration of HMT. The binding of (/sup 3/H)HMT to DNA was measured parallel with cell cycle analyses. Treatments with HMT at concentrations corresponding to about 1 HMT bound per 10(6) base pairs of DNA led to the accumulation of cells with predominantly G2 DNA content. At higher concentrations (2 to 3 HMT/10(6) base pairs), the cells were blocked in the S and G1 phases. In conclusion, it was shown that extremely sparse substitution of HMT to DNA blocks melanoma cells in the G2 phase or other phases of the cell cycle in a dose-dependent manner.

  18. Light scattering by a coated infinite cylinder in an absorbing medium.

    PubMed

    Lee, Siu-Chun

    2011-06-01

    The scattering formulation for a coated infinite cylinder in an absorbing medium is presented in this paper. The cylinder is subjected to an arbitrarily polarized plane wave propagating in a general direction at the cylinder. The refractive index and magnetic permeability of the host medium, as well as those for the core and coating of the cylinder, can be real or complex. The scattering and extinction efficiencies and the scattering amplitudes are derived for both the near field and the far field. As the medium is absorbing, the "true" extinction and scattering efficiencies are derived based on the radiative energy outflow at the surface of the cylinder. The radiative efficiencies in the far field are denoted as "apparent" properties because they include absorption by the intervening medium. The influence of the refractive index and permeability of the host medium on the scattering properties of a coated cylinder is illustrated by numerical examples.

  19. Development of ultraviolet electroabsorption modulators and light emitting diodes based on AlGaN alloys

    NASA Astrophysics Data System (ADS)

    Kao, Chen-Kai

    The research in this dissertation addressed the development of ultraviolet (UV) electroabsorption modulators and ultraviolet light emitting diodes (UV-LEDs), covering the spectral range from 360 to 265 nm. The materials system for both types of devices is the AlGaN alloys, either in bulk or quantum well (QW) form, grown by plasma-assisted molecular beam epitaxy (MBE). Potential applications of these devices either individually or in combination include UV non-line-of-sight free-space-optical communications, UV sensing and spectroscopic systems, Q-switched pulsed lasers, water/air purification and various medical applications. Optical modulators based on cubic III-V semiconductors have been the subject of extensive research over the past several years. Such devices are typically based on the quantum-confined Stark effect to modify the absorption spectrum of multiple-quantum-well active regions. On the other hand, in wurtzite III-Nitride semiconductors, strong electric fields are already present in the quantum wells due to intrinsic and piezoelectric polarizations; as a result, an even greater change in absorption is achievable, especially if the internal fields are compensated by the external bias so that the net field in the quantum wells is reduced. A number of UV electroabsorption modulators based on Schottky barriers on bulk GaN and GaN /AlGaN multiple quantum wells (MQWs) were designed, fabricated and characterized. Record modulation ratio of 30 % was obtained from bulk GaN Schottky barrier modulators at the excitonic resonant energy of 3.45 eV (360 nm) upon the application of 12 V reverse bias. Similarly, record modulation ratio of 43% was obtained from GaN / AlGaN MQWs Schottky barrier modulators at the excitonic resonant energy of 3.48 eV (356 nm) upon the application of 17 V reverse bias. The external quantum efficiency (EQE) of AlGaN based deep UV LEDS is relatively low (˜1% at 270 nm). This is generally attributed to the poor internal quantum efficiency

  20. Organic matrix effects on the formation of light-absorbing compounds from α-dicarbonyls in aqueous salt solution.

    PubMed

    Drozd, Greg T; McNeill, V Faye

    2014-04-01

    Aqueous-phase reactions of organic compounds are of general importance in environmental systems. Reactions of α-dicarbonyl compounds in the aqueous phase of atmospheric aerosols can impact their climate-relevant physical properties including hygroscopicity and absorption of light. Less-reactive water-soluble organic compounds may contribute an organic matrix component to the aqueous environment, potentially impacting the reaction kinetics. In this work we demonstrate the effects of organic matrices on the self-reactions of glyoxal (Gly) and methylglyoxal (mGly) in aqueous solutions containing ammonium sulfate. At an organic-to-sulfate mass ratio of 2 : 1, carbohydrate-like matrices resembling oxidized organic aerosol material reduce the rate of formation of light-absorbing products by up to an order of magnitude. The greatest decreases in the reaction rates were observed for organic matrices with smaller, more linear molecular structures. Initial UV-Vis spectra, product studies, relative rate data, acidity changes, and viscosity measurements suggest that shifts in carbonyl equilibria, due in part to (hemi)acetal formation with the matrix, reduce the rate of formation of light-absorbing imidazole and oligomer species.

  1. Arctic climate response to forcing from light-absorbing particles in snow and sea ice in CESM

    NASA Astrophysics Data System (ADS)

    Goldenson, N.; Doherty, S. J.; Bitz, C. M.; Holland, M. M.; Light, B.; Conley, A. J.

    2012-02-01

    The presence of light-absorbing aerosol particles deposited on arctic snow and sea ice influences the surface albedo, causing greater shortwave absorption, warming, and loss of snow and sea ice, lowering the albedo further. The Community Earth System Model version 1 (CESM1) now includes the radiative effects of light-absorbing particles in snow on land and sea ice and in sea ice itself. We investigate the model response to the deposition of black carbon and dust to both snow and sea ice. For these purposes we employ a slab ocean version of CESM1, using the Community Atmosphere Model version 4 (CAM4), run to equilibrium for year 2000 levels of CO2 and fixed aerosol deposition. We construct experiments with and without aerosol deposition, with dust or black carbon deposition alone, and with varying quantities of black carbon and dust to approximate year 1850 and 2000 deposition fluxes. The year 2000 deposition fluxes of both dust and black carbon cause 1-2 °C of surface warming over large areas of the Arctic Ocean and sub-Arctic seas in autumn and winter and in patches of Northern land in every season. Atmospheric circulation changes are a key component of the surface-warming pattern. Arctic sea ice thins by on average about 30 cm. Simulations with year 1850 aerosol deposition are not substantially different from those with year 2000 deposition, given constant levels of CO2. The climatic impact of particulate impurities deposited over land exceeds that of particles deposited over sea ice. Even the surface warming over the sea ice and sea ice thinning depends more upon light-absorbing particles deposited over land. For CO2 doubled relative to year 2000 levels, the climate impact of particulate impurities in snow and sea ice is substantially lower than for the year 2000 equilibrium simulation.

  2. Arctic climate response to forcing from light-absorbing particles in snow and sea ice in CESM

    NASA Astrophysics Data System (ADS)

    Goldenson, N.; Doherty, S. J.; Bitz, C. M.; Holland, M. M.; Light, B.; Conley, A. J.

    2012-09-01

    The presence of light-absorbing aerosol particles deposited on arctic snow and sea ice influences the surface albedo, causing greater shortwave absorption, warming, and loss of snow and sea ice, lowering the albedo further. The Community Earth System Model version 1 (CESM1) now includes the radiative effects of light-absorbing particles in snow on land and sea ice and in sea ice itself. We investigate the model response to the deposition of black carbon and dust to both snow and sea ice. For these purposes we employ a slab ocean version of CESM1, using the Community Atmosphere Model version 4 (CAM4), run to equilibrium for year 2000 levels of CO2 and fixed aerosol deposition. We construct experiments with and without aerosol deposition, with dust or black carbon deposition alone, and with varying quantities of black carbon and dust to approximate year 1850 and 2000 deposition fluxes. The year 2000 deposition fluxes of both dust and black carbon cause 1-2 °C of surface warming over large areas of the Arctic Ocean and sub-Arctic seas in autumn and winter and in patches of Northern land in every season. Atmospheric circulation changes are a key component of the surface-warming pattern. Arctic sea ice thins by on average about 30 cm. Simulations with year 1850 aerosol deposition are not substantially different from those with year 2000 deposition, given constant levels of CO2. The climatic impact of particulate impurities deposited over land exceeds that of particles deposited over sea ice. Even the surface warming over the sea ice and sea ice thinning depends more upon light-absorbing particles deposited over land. For CO2 doubled relative to year 2000 levels, the climate impact of particulate impurities in snow and sea ice is substantially lower than for the year 2000 equilibrium simulation.

  3. High-space resolution imaging plate analysis of extreme ultraviolet (EUV) light from tin laser-produced plasmas

    NASA Astrophysics Data System (ADS)

    Musgrave, Christopher S. A.; Murakami, Takehiro; Ugomori, Teruyuki; Yoshida, Kensuke; Fujioka, Shinsuke; Nishimura, Hiroaki; Atarashi, Hironori; Iyoda, Tomokazu; Nagai, Keiji

    2017-03-01

    With the advent of high volume manufacturing capabilities by extreme ultraviolet lithography, constant improvements in light source design and cost-efficiency are required. Currently, light intensity and conversion efficiency (CE) measurments are obtained by charged couple devices, faraday cups etc, but also phoshpor imaging plates (IPs) (BaFBr:Eu). IPs are sensitive to light and high-energy species, which is ideal for studying extreme ultraviolet (EUV) light from laser produced plasmas (LPPs). In this work, we used IPs to observe a large angular distribution (10°-90°). We ablated a tin target by high-energy lasers (1064 nm Nd:YAG, 1010 and 1011 W/cm2) to generate the EUV light. The europium ions in the IP were trapped in a higher energy state from exposure to EUV light and high-energy species. The light intensity was angular dependent; therefore excitation of the IP depends on the angle, and so highly informative about the LPP. We obtained high-space resolution (345 μm, 0.2°) angular distribution and grazing spectrometer (5-20 nm grate) data simultaneously at different target to IP distances (103 mm and 200 mm). Two laser systems and IP types (BAS-TR and BAS-SR) were also compared. The cosine fitting values from the IP data were used to calculate the CE to be 1.6% (SD ± 0.2) at 13.5 nm 2% bandwidth. Finally, a practical assessment of IPs and a damage issue are disclosed.

  4. Quantitative Investigation of Efficiency of Ultraviolet and Visible Light in Eradication of Candida albicans In Vitro

    PubMed Central

    Maver-Bišćanin, Mirela; Mravak-Stipetić, Marinka; Bukovski, Suzana; Bišćanin, Alen

    2014-01-01

    Abstract Objective: The aim of this study was to quantitatively investigate the efficiency of the ultraviolet (UV) and visible light in eradication of Candida albicans in vitro; in particular, to determine, for selected wavelengths, the specific eradication coefficients and thresholds in terms of energy density levels required to effect 3.0log10 and 4.0log10 reduction. Background data: Oral candidosis is the most common infection of the oral cavity and is caused by Candida species. The widespread use of topical and systemic antifungal agents as conventional treatment for oral candidosis has resulted in the development of resistance in C. albicans. Therefore, it has become necessary to develop alternative therapies for the treatment of oral candidosis. Methods: C. albicans ATCC® 90028™ was irradiated with 254 nm, 365 nm, 406 nm, 420 nm, and broadband Xe spectrum. For each wavelength, a fit of experimental data (survival fraction vs. applied energy density) with an exponential decay function enabled estimation of the specific eradication coefficients and thresholds. Results: Based on estimated specific efficiencies (Δ) and eradication thresholds (ET) of the investigated wavelengths, the ranking in eradication efficiency of C. albicans (most to least effective) is: 254 nm (Δ=6.1 mJ/cm−2, ET99.99=56 mJ/cm−2), broadband Xe spectrum (Δ=27.7 mJ/cm−2, ET99.99=255 mJ/cm−2), 365 nm (Δ=4.3 J/cm−2, ET99.99=39 J/cm−2), 420 nm (Δ=0.65 J/cm−2, ET99.99=6 J/cm−2), and 406 nm (Δ=11.4 J/cm−2, ET99.99=104 J/cm−2). Conclusions: The results provide insight into the wavelength-dependent dynamics of eradication of C. albicans. For each investigated wavelength, the eradication coefficient and corresponding eradication threshold were estimated. The observed different eradication efficiencies are consequence of different spectrally dependent inactivation mechanisms. The established methodology enables unambiguous quantitative

  5. Theory of photoselection by intense light pulses. Influence of reorientational dynamics and chemical kinetics on absorbance measurements.

    PubMed Central

    Ansari, A; Szabo, A

    1993-01-01

    The theory of absorbance measurements on a system (e.g., chromophore(s) in a protein) that undergoes a sequence of reactions initiated by a linearly polarized light pulse is developed for excitation pulses of arbitrary intensity. This formalism is based on a set of master equations describing the time evolution of the orientational distribution function of the various species resulting from excitation, reorientational dynamics, and chemical kinetics. For intense but short excitation pulses, the changes in absorbance (for arbitrary polarization directions of the excitation and probe pulses) and the absorption anisotropy are expressed in terms of reorientational correlation functions. The influence of the internal motions of the chromophore as well as the overall motions of the molecules is considered. When the duration of the excitation pulse is long compared to the time-scale of internal motions but comparable to the overall correlation time of the molecule that is reorienting isotropically, the problem of calculating the changes in absorbance is reduced to the solution of a set of first-order coupled differential equations. Emphasis is placed on obtaining explicit results for quantities that are measured in photolysis and fluorescence experiments so as to facilitate the analysis of experimental data. PMID:8471729

  6. Photocatalytic performance of the SiO2 sphere/ n-type TiO2/ p-type CuBiS2 composite catalysts coated with different contents of Ag nanoparticles under ultraviolet and visible light irradiations

    NASA Astrophysics Data System (ADS)

    Abdullah, Hairus; Kuo, Dong-Hau

    2016-08-01

    Photocatalytic performance of the SiO2 sphere/ n-type TiO2/ p-type CuBiS2 composite catalysts with different contents of silver nanoparticles (abbreviated as SiO2/ n-TiO2/ p-CuBiS2/Ag) toward the photodegradation of Acid Black 1 ( AB 1) dye under ultraviolet (UV) and visible light was investigated. The composite catalyst spheres were analyzed their crystal structure, microstructure, optical absorbance capabilities, and photodegradation capabilities of AB 1 dye. The best photodegradation performances of the 20 mg composite powder with only ~5 mg photoactive catalysts showed the degradation of AB 1 dye in 5 min under UV and 60 min under visible light irradiations. The concept of composite catalyst with numerous nano p- n diodes and its photodegradation mechanism were proposed.

  7. Transmission of ultrashort light pulses with oblique incidence on an absorbent or disperse medium

    NASA Astrophysics Data System (ADS)

    Diaz, H. R.; Panameno, E. A. M.; Otero, M. M. M.; Armenta, C. A. A.

    2004-06-01

    In this work is studied the transmission of linearly polarized optical pulses, which arrive from vacuum into a material medium at arbitrary angle of incidence. The considered geometry take into account that the electric field has parallel and perpendicular components to the plane of incidence. Analitical expressions are obtained for electrical and magnetic fields inside the material medium, the functional form of the expressions allow to relate the imaginary and real parts of the wave vector with the loss of the pulse spectral amplitud and with its propagation direction, respectively. It is found a generalized integral relation for the Poynting vector, in the time domain, which is valid for dispersive and absorbent media.

  8. Ultraviolet light and osmotic stress: Activation of the JNK cascade through multiple growth factor and cytokine receptors

    SciTech Connect

    Rosette, C.; Karin, M.

    1996-11-15

    Exposure of mammalian cells to ultraviolet (UV) light or high osmolarity strongly activated the c-Jun amino-terminal protein kinase (JNK) cascade, causing induction of many target genes. Exposure to UV light or osmotic shock induced clustering and internalization of cell surface receptors for epidermal growth factor (EGF), tumor necrosis factor (TNF), and interleukin-1 (IL-1). Activation of the EGF and TNF receptors was also detected biochemically. Whereas activation of each receptor alone resulted in modest activation of JNK, coadministration of EGF, IL-1, and TNF resulted in a strong synergistic response equal to that caused by exposure to osmotic shock or UV light. Inhibition of clustering or receptor down-regulation attenuated both the osmotic shock and UV responses. Physical stresses may perturb the cell surface or alter receptor conformation, thereby subverting signaling pathways normally used by growth factors and cytokines. 24 refs., 5 figs.

  9. High Mobility Flexible Amorphous IGZO Thin-Film Transistors with a Low Thermal Budget Ultra-Violet Pulsed Light Process.

    PubMed

    Benwadih, M; Coppard, R; Bonrad, K; Klyszcz, A; Vuillaume, D

    2016-12-21

    Amorphous, sol-gel processed, indium gallium zinc oxide (IGZO) transistors on plastic substrate with a printable gate dielectric and an electron mobility of 4.5 cm(2)/(V s), as well as a mobility of 7 cm(2)/(V s) on solid substrate (Si/SiO2) are reported. These performances are obtained using a low temperature pulsed light annealing technique. Ultraviolet (UV) pulsed light system is an innovative technique compared to conventional (furnace or hot-plate) annealing process that we successfully implemented on sol-gel IGZO thin film transistors (TFTs) made on plastic substrate. The photonic annealing treatment has been optimized to obtain IGZO TFTs with significant electrical properties. Organic gate dielectric layers deposited on this pulsed UV light annealed films have also been optimized. This technique is very promising for the development of amorphous IGZO TFTs on plastic substrates.

  10. A study of the photolightening mechanism of red hair with visible and ultraviolet light: comparison with blond hair.

    PubMed

    Takahashi, T

    2005-01-01

    The photolightening behavior of red hair was investigated. Red hair was found to lighten to a similar extent by irradiation from both ultraviolet (UV) and visible (VIS) light. Under the same irradiating conditions, blond hair was lightened by VIS light but did not lighten by UV light until it was washed after irradiation (1). These different photolightening behaviors of red and blond hair are supposed to be due to differences in their melanin compositions. The dominant type of melanin in red hair is pheomelanin; while blond hair investigated in the previous work contained both eumelanin and pheomelanin, with mainly eumelanin (2). Consequently, in this investigation, the photolightening behaviors of red and blond hair were compared to clarify the differences in photosensitivity between the two types of melanin.

  11. Angular Dependence of Ionization by Circularly Polarized Light Calculated with Time-Dependent Configuration Interaction with an Absorbing Potential.

    PubMed

    Hoerner, Paul; Schlegel, H Bernhard

    2017-02-16

    The angular dependence of ionization by linear and circularly polarized light has been examined for N2, NH3, H2O, CO2, CH2O, pyrazine, methyloxirane, and vinyloxirane. Time-dependent configuration interaction with single excitations and a complex absorbing potential was used to simulate ionization by a seven cycle 800 nm cosine squared pulse with intensities ranging from 0.56 × 10(14) to 5.05 × 10(14) W cm(-2). The shapes of the ionization yield for linearly polarized light can be understood primarily in terms of the nodal structure of the highest occupied orbitals. Depending on the orbital energies, ionization from lower-lying orbitals may also make significant contributions to the shapes. The shapes of the ionization yield for circularly polarized light can be readily explained in terms of the shapes for linearly polarized light. Averaging the results for linear polarization over orientations perpendicular to the direction of propagation yields shapes that are in very good agreement with direct calculations of the ionization yield by circularly polarized light.

  12. 'Self-absorbed' GeV light curves of gamma-ray burst afterglows

    SciTech Connect

    Panaitescu, A.; Vestrand, W. T.; Woźniak, P.

    2014-06-10

    We investigate the effect that the absorption of high-energy (above 100 MeV) photons produced in gamma-ray burst afterglow shocks has on the light curves and spectra of Fermi Large Area Telescope (LAT) afterglows. Afterglows produced by the interaction of a relativistic outflow with a wind-like medium peak when the blast wave deceleration sets in, and the afterglow spectrum could be hardening before that peak, as the optical thickness to pair formation is decreasing. In contrast, in afterglows produced in the interaction with a homogeneous medium, the optical thickness to pair formation should increase and yield a light curve peak when it reaches unity, followed by a fast light curve decay, accompanied by spectral softening. If energy is injected in the blast wave, then the accelerated increase of the optical thickness yields a convex afterglow light curve. Other features, such as a double-peak light curve or a broad hump, can arise from the evolution of the optical thickness to photon-photon absorption. Fast decays and convex light curves are seen in a few LAT afterglows, but the expected spectral softening is rarely seen in (and difficult to measure with) LAT observations. Furthermore, for the effects of photon-photon attenuation to shape the high-energy afterglow light curve without attenuating it too much, the ejecta initial Lorentz factor must be in a relatively narrow range (50-200), which reduces the chance of observing those effects.

  13. Phenolic carbonyls undergo rapid aqueous photodegradation to form low-volatility, light-absorbing products

    NASA Astrophysics Data System (ADS)

    Smith, Jeremy D.; Kinney, Haley; Anastasio, Cort

    2016-02-01

    We investigated the aqueous photochemistry of six phenolic carbonyls - vanillin, acetovanillone, guaiacyl acetone, syringaldehyde, acetosyringone, and coniferyl aldehyde - that are emitted from wood combustion. The phenolic carbonyls absorb significant amounts of solar radiation and decay rapidly via direct photodegradation, with lifetimes (τ) of 13-140 min under Davis, CA winter solstice sunlight at midday (solar zenith angle = 62°). The one exception is guaiacyl acetone, where the carbonyl group is not directly connected to the aromatic ring: This species absorbs very little sunlight and undergoes direct photodegradation very slowly (τ > 103 min). We also found that the triplet excited states (3C*) of the phenolic carbonyls rapidly oxidize syringol (a methoxyphenol without a carbonyl group), on timescales of 1-5 h for solutions containing 5 μM phenolic carbonyl. The direct photodegradation of the phenolic carbonyls, and the oxidation of syringol by 3C*, both efficiently produce low volatility products, with SOA mass yields ranging from 80 to 140%. Contrary to most aliphatic carbonyls, under typical fog conditions we find that the primary sink for the aromatic phenolic carbonyls is direct photodegradation in the aqueous phase. In areas of significant wood combustion, phenolic carbonyls appear to be small but significant sources of aqueous SOA: over the course of a few hours, nearly all of the phenolic carbonyls will be converted to SOA via direct photodegradation, enhancing the POA mass from wood combustion by approximately 3-5%.

  14. 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

  15. 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.

  16. The vitamin D hypothesis revisited: race-based disparities in birth outcomes in the United States and ultraviolet light availability.

    PubMed

    Thayer, Zaneta M

    2014-04-15

    Skin color has been proposed to contribute to race-based health disparities in the United States because of differences in ultraviolet (UV) light-induced vitamin D synthesis. The prediction of this hypothesis, herein named the UVD hypothesis, is that racial disparities in health outcomes are correlated with UV light availability. This paper investigates whether UV light availability is associated with disparities in the rates of low birth weight (LBW) and preterm birth (PTB) between whites and blacks, because these outcomes are thought to be influenced by vitamin D status and to shape disease risk in later life. Data on LBW and PTB from 2007 (n = 2,825,620 births) were compared with data on UV light exposure across the United States. Contrary to the predictions of the UVD hypothesis, LBW and PTB rate disparities were greatest in states with the highest UV light exposure. Notably, income inequality was positively and significantly related to LBW and PTB disparities, even after controlling for UV light availability. The results of this analysis demonstrate that there is a significant environmental gradient in racial disparities in birth outcomes in the United States, but other social or environmental factors associated with living in the southern United States are likely stronger contributors to disparities in birth outcomes than UV light-induced vitamin D status.

  17. Peculiarities of propagation of quasi-diffraction-free light beams in strongly scattering absorbing media

    SciTech Connect

    Katsev, I L; Prikhach, A S; Kazak, N S; Kroening, M

    2006-04-30

    Based on the relation between the theory of light field coherence and theory of radiation transfer in scattering media, a method is proposed for calculating the illumination distribution produced by coherent quasi-diffraction-free beams at different penetration depths of radiation into scattering media such as biological tissues. The method uses the optical transfer function or the point spread function (PSF) of the medium. A simple and convenient analytic PSF model is described. Examples of the illumination distribution produced by a Bessel light beam in a medium with optical parameters typical of real biological tissues are presented. It is shown that the half-width of the axial maximum of a Bessel light beam scattered due to scattering almost does not increase up to optical depths where the contribution of multiple scattering is already considerable. (light beams)

  18. Ultraviolet-C light inactivation of Penicillium expansum on fruit surfaces

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Understanding the influence of fruit surface morphology on ultraviolet-C (UV-C 254 nm) inactivation of microorganisms is required for designing effective treatment systems. In this study, we analyzed UV-C inactivation of Penicillium expansum that was inoculated onto the surface of organic fruits. Re...

  19. Antioxidant characterization and sensory evaluation during storage of ultraviolet-B light exposed baby carrots (abstract)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Baby carrot processing induces wounding stress activation of phenylalanine ammonia-lyase (PAL), enhancing its nutrient content by increasing synthesis of secondary metabolites. Ultraviolet-B (UV-B) exposure further promotes the formation of soluble phenolic compounds, significantly increasing antiox...

  20. Modeling Ultraviolet (UV) Light Emitting Diode (LED) Energy Propagation in Reactor Vessels

    DTIC Science & Technology

    2014-03-27

    urban wastewater effluent than a single wavelength used alone (Chevremont, Farnet, Coulomb, & Boudenne, 2012; Oguma, Kita, Sakai, Murakami...into waste streams. Certain chemicals may be detrimental to the effectiveness of municipal wastewater treatment plants. This can lead to reduced...introduced to wastewater treatment plants. One of these methods includes an Advanced Oxidation Process (AOP) which uses ultraviolet (UV) energy and

  1. EFFECTS OF LABORATORY ULTRAVIOLET LIGHT AND NATURAL SUNLIGHT ON SURVIVAL AND DEVELOPMENT OF RANA PIPIENS

    EPA Science Inventory

    Changes in solar ultraviolet (UV) radiation have been proposed as a possible factor contributing to seeming increases in hindlimb malformations in anuran amphibians in North America. A primary purpose of this study was to reproduce results from an earlier experiment in which Ran...

  2. Interactions of Changing Solar Ultraviolet Radiation and Climate with Light Induced Chemical Reactions in Aquatic Environments

    EPA Science Inventory

    Changes in the ozone layer over the past two decades have resulted in increases in solar ultraviolet radiation that reach the surface of North American aquatic environments. Concurrent changes in atmospheric CO2 are resulting in changes in stratification and precipitation that ar...

  3. Virulence of Listeria monocytogenes following repeated exposure to Ultraviolet (254nm) Light

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The foodborne pathogen Listeria monocytogenes is an occasional contaminant of ready-to-eat meat products such as frankfurters. Frankfurters can be contaminated following cooking and prior to packaging by contact with contaminated surfaces such as conveyors and packaging equipment. Ultraviolet Ligh...

  4. BRIGHT RAY-LIKE FEATURES IN THE AFTERMATH OF CORONAL MASS EJECTIONS: WHITE LIGHT VERSUS ULTRAVIOLET SPECTRA

    SciTech Connect

    Ciaravella, A.; Webb, D. F.; Giordano, S.; Raymond, J. C.

    2013-03-20

    Current sheets (CSs) are important signatures of magnetic reconnection in the eruption of confined solar magnetic structures. Models of coronal mass ejections (CMEs) involve formation of a CS connecting the ejected flux rope with the post-eruption magnetic loops. CSs have been identified in white light (WL) images of CMEs as narrow rays trailing the outward moving CME core, and in ultraviolet spectra as narrow bright features emitting the [Fe XVIII] line. In this work, samples of rays detected in WL images or in ultraviolet spectra have been analyzed. Temperatures, widths, and line intensities of the rays have been measured, and their correlation to the CME properties has been studied. The samples show a wide range of temperatures with hot, coronal, and cool rays. In some cases, the UV spectra support the identification of rays as CSs, but they show that some WL rays are cool material from the CME core. In many cases, both hot and cool material are present, but offset from each other along the Ultraviolet Coronagraph Spectrometer slit. We find that about 18% of the WL rays show very hot gas consistent with the CS interpretation, while about 23% show cold gas that we attribute to cool prominence material draining back from the CME core. The remaining events have ordinary coronal temperatures, perhaps because they have relaxed back to a quiescent state.

  5. Near ultraviolet light emitting diodes using ZnMgO:N/ZnO hetero-junction grown by MOVPE

    NASA Astrophysics Data System (ADS)

    Fujita, Yasuhisa; Yanase, Shogo; Nishikori, Hirokazu; Hiragino, Yuto; Furubayashi, Yutaka; Lin, Jie; Yoshida, Toshiyuki

    2017-04-01

    A ZnMgO:N/ZnO/ZnO:Ga single hetero-junction light emitting diode structure on Al2O3 (11 2 ̅0) substrate was fabricated by metalorganic vapor phase epitaxy. By using ZnMgO:N as a substitute for a ZnO:N top layer of a homojunction LED, improved rectifying current-voltage characteristics were obtained. Although the device had a heating problem and the luminescent area was partly in the ZnMgO:N layer, a sharp ultraviolet electroluminescence emission at 3.17 eV was successfully observed at room temperature.

  6. A simple and rapid method for evaluating the survival of xeroderma pigmentosum lymphoid lines after irradiation with ultraviolet light

    SciTech Connect

    Moshell, A.N.; Tarone, R.E.; Newfield, S.A.; Andrews, A.D.; Robbins, J.H.

    1981-04-01

    A simple, rapid, and reproducible test has been developed to measure the viability of cells after irradiation with ultraviolet light (UV). Epstein-Barr virus-transformed lymphoid lines, derived from patients with xeroderma pigmentosum (XP), were irradiated with UV, and the post-UV viability of the lymphoid lines was determined by the trypan blue dye exclusion method. The relative post-UV survival of the patients' lymphoid lines was similar to the relative post-UV survival of the patients' fibroblast strains.

  7. Indium Tin Oxide-Free Transparent Conductive Electrode for GaN-Based Ultraviolet Light-Emitting Diodes.

    PubMed

    Kim, Ja-Yeon; Jeon, Jong-Hyun; Kwon, Min-Ki

    2015-04-22

    Transparent conducting electrodes are important components of highly efficient ultraviolet light-emitting diodes (UV LEDs). Indium tin oxide (ITO) is commonly used to form a current spreading layer, but its UV-range optical transparency is limited with a low sheet resistance. We demonstrate a simple solution-based coating technique to obtain large-area, highly uniform, and conductive silver-nanowire-based electrodes that exhibit UV-range optical transparency better than that of ITO for the same sheet resistance. The UV LEDs fabricated using this current spreading layer showed improved optical power emission as well as improvement in electrical properties.

  8. 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.

  9. LIGHT BEAMS: Peculiarities of propagation of quasi-diffraction-free light beams in strongly scattering absorbing media

    NASA Astrophysics Data System (ADS)

    Katsev, I. L.; Prikhach, A. S.; Kazak, N. S.; Kroening, M.

    2006-04-01

    Based on the relation between the theory of light field coherence and theory of radiation transfer in scattering media, a method is proposed for calculating the illumination distribution produced by coherent quasi-diffraction-free beams at different penetration depths of radiation into scattering media such as biological tissues. The method uses the optical transfer function or the point spread function (PSF) of the medium. A simple and convenient analytic PSF model is described. Examples of the illumination distribution produced by a Bessel light beam in a medium with optical parameters typical of real biological tissues are presented. It is shown that the half-width of the axial maximum of a Bessel light beam scattered due to scattering almost does not increase up to optical depths where the contribution of multiple scattering is already considerable.

  10. Deep-ultraviolet light-emitting diodes with external quantum efficiency higher than 20% at 275 nm achieved by improving light-extraction efficiency

    NASA Astrophysics Data System (ADS)

    Takano, Takayoshi; Mino, Takuya; Sakai, Jun; Noguchi, Norimichi; Tsubaki, Kenji; Hirayama, Hideki

    2017-03-01

    Enhancing the light-extraction efficiency is the key issue for realizing highly efficient AlGaN-based ultraviolet light-emitting diodes (UV-LEDs). We introduced several features to improve the light extraction: a transparent AlGaN:Mg contact layer, a Rh mirror electrode, an AlN template on a patterned sapphire substrate, and encapsulation resin. The combination of the AlGaN:Mg contact layer and the Rh mirror electrode significantly improved the output power and the external quantum efficiency (EQE) of UV-LEDs. By introducing the aforementioned features, a maximum EQE of >20% at an emission wavelength of 275 nm and a 20-mA direct current was achieved.

  11. Absorption and scattering of light by pigment particles in solar-absorbing paints.

    PubMed

    Gunde, M K; Orel, Z C

    2000-02-01

    The optical properties of black-pigmented solar absorbing paint were analyzed phenomenologically by use of the Kubelka-Munk theory, including correction for reflection on front and rear surfaces. The effective absorption and scattering coefficients and the efficiency curves for absorption and scattering were calculated for coatings with different pigment-to-volume concentration ratios. The dependence of absorption and scattering efficiency on the pigment-to-volume concentration ratio was analyzed by reference to theoretical data in the literature. It was concluded that, during drying and curing of coatings, spherical primary pigment particles most likely collect in elongated groups oriented perpendicularly to the coating surface. Formation of such groups helps in understanding the independent measurements of solar absorptance.

  12. Symmetry-Breaking Charge Transfer of Visible Light Absorbing Systems: Zinc Dipyrrins

    PubMed Central

    2015-01-01

    Zinc dipyrrin complexes with two identical dipyrrin ligands absorb strongly at 450–550 nm and exhibit high fluorescence quantum yields in nonpolar solvents (e.g., 0.16–0.66 in cyclohexane) and weak to nonexistent emission in polar solvents (i.e., <10–3, in acetonitrile). The low quantum efficiencies in polar solvents are attributed to the formation of a nonemissive symmetry-breaking charge transfer (SBCT) state, which is not formed in nonpolar solvents. Analysis using ultrafast spectroscopy shows that in polar solvents the singlet excited state relaxes to the SBCT state in 1.0–5.5 ps and then decays via recombination to the triplet or ground states in 0.9–3.3 ns. In the weakly polar solvent toluene, the equilibrium between a localized excited state and the charge transfer state is established in 11–22 ps. PMID:25270268

  13. Photophysical properties of praseodymium complexes with aromatic carboxylic acids: double light conversion both in ultraviolet and visible region.

    PubMed

    Yan, Bing; Wang, Weijing; Song, Yishan

    2007-04-01

    A series of luminescent praseodymium complexes with different aromatic carboxylic acids have been synthesized and characterized. The photophysical properties of these complexes have been studied with ultraviolet spectra, phosphorescence spectra and fluorescence spectra. Ultraviolet absorption spectra show that the praseodymium complexes systems with aromatic carboxylate form the more extensive conjugated systems to be suitable for the distribution of electron in the whole coordination environment, resulting in the energy decrease and red-shifts of ultraviolet spectral bands. Phosphorescence spectra suggest that excited triplet state of aromatic carboxylic acids, which can indicate the energy match and intermolecular energy transfer process between the excited triplet state of ligands and the resonant emissive energy level of Pr ions. The emission spectra of all praseodymium complexes show two emission peaks under the excitation band of 245 nm at about 395 and 595 nm, respectively, while one peak at about 595 nm under 415 nm excitation, which attributed to be 1S0-->1I6 (395 nm) transition and the characteristic emission 1D2-->3H4 (595 nm) transition of Pr3+ ion. The 1S0-->1I6 transition can be speculated to belong to the transition of charge transfer state, and the 1D2-->3H4 can be further proved that there exists an antenna effect in the luminescence of praseodymium with aromatic carboxylic acids. In conclusion, the praseodymium complexes systems can realize the double proton light conversion both in the ultraviolet and visible region, which can be further studied to have potential application.

  14. Pan-Arctic enhancements of light absorbing aerosol concentrations due to North American boreal forest fires during summer 2004

    NASA Astrophysics Data System (ADS)

    Stohl, A.; Andrews, E.; Burkhart, J. F.; Forster, C.; Herber, A.; Hoch, S. W.; Kowal, D.; Lunder, C.; Mefford, T.; Ogren, J. A.; Sharma, S.; Spichtinger, N.; Stebel, K.; Stone, R.; StröM, J.; TøRseth, K.; Wehrli, C.; Yttri, K. E.

    2006-11-01

    During summer of 2004, about 2.7 million hectare of boreal forest burned in Alaska, the largest annual area burned on record, and another 3.1 million hectare burned in Canada. This study explores the impact of emissions from these fires on light absorbing aerosol concentration levels, aerosol optical depths (AOD), and albedo at the Arctic stations Barrow (Alaska), Alert (Canada), Summit (Greenland), and Zeppelin/Ny Ålesund on Spitsbergen (Norway). The Lagrangian particle dispersion model FLEXPART was run backward from these sites to identify periods that were influenced by forest fire pollution plumes. It is shown that the fires led to enhanced values of particle light absorption coefficients (σap) at all of these sites. Barrow, about 1000 km away from the fires, was affected by several fire pollution plumes, one leading to spectacularly high 3-hour mean σap values of up to 32 Mm-1, more than the highest values measured in Arctic Haze. AOD measurements for a wavelength of 500 nm saturated but were estimated at above 4-5 units, unprecedented in the station records. Fire plumes were transported through the atmospheric column over Summit continuously for 2 months, during which all measured AOD values were enhanced, with maxima up to 0.4-0.5 units. Equivalent black carbon concentrations at the surface at Summit were up to 600 ng m-3 during two major episodes, and Alert saw at least one event with enhanced σap values. FLEXPART results show that Zeppelin was located in a relatively unaffected part of the Arctic. Nevertheless, there was a 4-day period with daily mean σap > 0.3 Mm-1, the strongest episode of the summer half year, and enhanced AOD values. Elevated concentrations of the highly source-specific compound levoglucosan positively confirmed that biomass burning was the source of the aerosols at Zeppelin. In summary, this paper shows that boreal forest fires can lead to elevated concentrations of light absorbing aerosols throughout the entire Arctic. Enhanced

  15. Productivity, absorbed photosynthetically active radiation, and light use efficiency in crops: implications for remote sensing of crop primary production.

    PubMed

    Gitelson, Anatoly A; Peng, Yi; Arkebauer, Timothy J; Suyker, Andrew E

    2015-04-01

    Vegetation productivity metrics such as gross primary production (GPP) at the canopy scale are greatly affected by the efficiency of using absorbed radiation for photosynthesis, or light use efficiency (LUE). Thus, close investigation of the relationships between canopy GPP and photosynthetically active radiation absorbed by vegetation is the basis for quantification of LUE. We used multiyear observations over irrigated and rainfed contrasting C3 (soybean) and C4 (maize) crops having different physiology, leaf structure, and canopy architecture to establish the relationships between canopy GPP and radiation absorbed by vegetation and quantify LUE. Although multiple LUE definitions are reported in the literature, we used a definition of efficiency of light use by photosynthetically active "green" vegetation (LUE(green)) based on radiation absorbed by "green" photosynthetically active vegetation on a daily basis. We quantified, irreversible slowly changing seasonal (constitutive) and rapidly day-to-day changing (facultative) LUE(green), as well as sensitivity of LUE(green) to the magnitude of incident radiation and drought events. Large (2-3-fold) variation of daily LUE(green) over the course of a growing season that is governed by crop physiological and phenological status was observed. The day-to-day variations of LUE(green) oscillated with magnitude 10-15% around the seasonal LUE(green) trend and appeared to be closely related to day-to-day variations of magnitude and composition of incident radiation. Our results show the high variability of LUE(green) between C3 and C4 crop species (1.43 g C/MJ vs. 2.24 g C/MJ, respectively), as well as within single crop species (i.e., maize or soybean). This implies that assuming LUE(green) as a constant value in GPP models is not warranted for the crops studied, and brings unpredictable uncertainties of remote GPP estimation, which should be accounted for in LUE models. The uncertainty of GPP estimation due to facultative and

  16. Stability of the Stevia-Derived Sweetener Rebaudioside A in Solution as Affected by Ultraviolet Light Exposure.

    PubMed

    Zhang, Jiewen; Bell, Leonard N

    2017-04-01

    Rebaudioside A is a natural noncaloric high-potency sweetener extracted from the leaves of Stevia rebaudiana. With rebaudioside A use increasing in foods, understanding the factors affecting its stability is necessary. This project evaluated the degradation rate constants of rebaudioside A in water, 0.1 M phosphate buffer, and 0.1 M citrate buffer at pH 3 and 7 as a function of ultraviolet (UV) light intensity (365 nm, 0 μW/cm(2) for dark conditions, 27 μW/cm(2) for low intensity, and 190 μW/cm(2) for high intensity) at 32.5 °C. Rebaudioside A stability was adversely affected by light exposure. The pseudo-1st-order degradation rate constants increased significantly (P < 0.05) with increasing light intensity in all solutions. Under dark conditions, rebaudioside A in phosphate buffers was more susceptible to breakdown than in water and citrate buffers at both pH levels. However, exposure to UV light resulted in rebaudioside A degradation occurring approximately 10 times faster in citrate than in phosphate buffers at both pH levels. The sensitivity of rebaudioside A to UV light was greater in citrate buffers than in water or phosphate buffers. The use of light-protective packaging for beverages containing rebaudioside A will improve its stability.

  17. Artificial sunlight and ultraviolet light induced photo-epoxidation of propylene over V-Ti/MCM-41 photocatalyst.

    PubMed

    Nguyen, Van-Huy; Lin, Shawn D; Wu, Jeffrey Chi-Sheng; Bai, Hsunling

    2014-01-01

    The light irradiation parameters, including the wavelength spectrum and intensity of light source, can significantly influence a photocatalytic reaction. This study examines the propylene photo-epoxidation over V-Ti/MCM-41 photocatalyst by using artificial sunlight (Xe lamp with/without an Air Mass 1.5 Global Filter at 1.6/18.5 mW·cm(-2)) and ultraviolet light (Mercury Arc lamp with different filters in the range of 0.1-0.8 mW·cm(-2)). This is the first report of using artificial sunlight to drive the photo-epoxidation of propylene. Over V-Ti/MCM-41 photocatalyst, the propylene oxide (PO) formation rate is 193.0 and 112.1 µmol·gcat (-1)·h(-1) with a PO selectivity of 35.0 and 53.7% under UV light and artificial sunlight, respectively. A normalized light utilization (NLU) index is defined and found to correlate well with the rate of both PO formation and C3H6 consumption in log-log scale. The light utilization with a mercury arc lamp is better than with a xenon lamp. The selectivity to PO remains practically unchanged with respect to NLU, suggesting that the photo-epoxidation occurs through the same mechanism under the conditions tested in this study.

  18. Ultraviolet light curves of galactic and extra-galactic classical CNO novae: PW Vul, OS, and LMC 1988 no. 1 and no. 2

    NASA Technical Reports Server (NTRS)

    Austin, S.; Starrfield, Sumner G.; Saizar, P.; Shore, Steven N.; Sonneborn, George

    1990-01-01

    In order to determine the comparative energy budgets of novae in outburst, the ultraviolet light curves for a number of novae are determined. The low dispersion IUE (International Ultraviolet Explorer) spectra of PW Vul 1984, OS And 1986, LMC 1988 number 1 and number 2 and obtained values for the integrated energy emitted in the wavelength interval from 1200 to 3400 A, not including the geocoronal Lyman-alpha emission line are re-examined. The light curves show that the brightness of the nova declines much more slowly in the ultraviolet than the optical, that the maximum brightness of the nova occurs much later in the ultraviolet than in the optical, and the peak luminosity is super Eddington for LMC 1988 number 2.

  19. Uncovering new thermal and mechanical behavior at the nanoscale using coherent extreme ultraviolet light

    NASA Astrophysics Data System (ADS)

    Hoogeboom-Pot, Kathleen Marie

    Tremendous recent progress in nanofabrication capabilities has made high-quality single-atomic layers and nanostructures with dimensions well below 50 nm commonplace, enabling unprecedented access to materials at the nanoscale. However, tools and techniques capable of characterizing the properties and function of nanosystems are still quite limited, leaving much of the fundamental physics that dominates material behavior in the deep nano-regime still unknown. Further understanding gained by studying nanoscale materials is critical both to fundamental science and to continued technological development. This thesis applies coherent extreme ultraviolet (EUV) light from tabletop high harmonic generation to study nanoscale systems on their intrinsic length and time scales (nanometers and femtoseconds, and above), specifically following thermal transport and acoustic dynamics. These studies have shown where and how nanostructured material properties can be quite different from their bulk counterparts. This has in turn allowed us to develop new theoretical descriptions to guide further work. By observing heat dissipation from the smallest nanostructure heat sources measured to date (at 20 nm in lateral size), this work uncovers a previously unobserved and unpredicted nanoscale thermal transport regime where both size and spacing of heat sources play a role in determining the heat dissipation effciency. Surprisingly, this shows that nanoscale heat sources can cool more quickly when spaced close together than when far apart. This discovery is significant to the engineering of thermal management in nanoscale systems and devices while also revealing new insight into the fundamental nature of thermal transport. Furthermore, we harness this new regime to demonstrate the first experimental measurement of the differential contributions of phonons with different mean free paths to thermal conductivity, down to mean free paths as short as 14 nm for the first time. The same

  20. A vision physiological estimation of ultraviolet window marking visibility to birds

    PubMed Central

    Ödeen, Anders

    2014-01-01

    Billions of birds are estimated to be killed in window collisions every year, worldwide. A popular solution to this problem may lie in marking the glass with ultraviolet reflective or absorbing patterns, which the birds, but not humans, would see. Elegant as this remedy may seem at first glance, few of its proponents have taken into consideration how stark the contrasts between ultraviolet and human visible light reflections or transmissions must be to be visible to a bird under natural conditions. Complicating matters is that diurnal birds differ strongly in how their photoreceptors absorb ultraviolet and to a lesser degree blue light. We have used a physiological model of avian colour vision to estimate the chromatic contrasts of ultraviolet markings against a natural scene reflected and transmitted by ordinary window glass. Ultraviolets markings may be clearly visible under a range of lighting conditions, but only to birds with a UVS type of ultraviolet vision, such as many passerines. To bird species with the common VS type of vision, ultraviolet markings should only be visible if they produce almost perfect ultraviolet contrasts and are viewed against a scene with low chromatic variation but high ultraviolet content. PMID:25320684

  1. A vision physiological estimation of ultraviolet window marking visibility to birds.

    PubMed

    Håstad, Olle; Odeen, Anders

    2014-01-01

    Billions of birds are estimated to be killed in window collisions every year, worldwide. A popular solution to this problem may lie in marking the glass with ultraviolet reflective or absorbing patterns, which the birds, but not humans, would see. Elegant as this remedy may seem at first glance, few of its proponents have taken into consideration how stark the contrasts between ultraviolet and human visible light reflections or transmissions must be to be visible to a bird under natural conditions. Complicating matters is that diurnal birds differ strongly in how their photoreceptors absorb ultraviolet and to a lesser degree blue light. We have used a physiological model of avian colour vision to estimate the chromatic contrasts of ultraviolet markings against a natural scene reflected and transmitted by ordinary window glass. Ultraviolets markings may be clearly visible under a range of lighting conditions, but only to birds with a UVS type of ultraviolet vision, such as many passerines. To bird species with the common VS type of vision, ultraviolet markings should only be visible if they produce almost perfect ultraviolet contrasts and are viewed against a scene with low chromatic variation but high ultraviolet content.

  2. Investigations on the emission in the extreme ultraviolet of a pseudospark based discharge light source

    NASA Astrophysics Data System (ADS)

    Bergmann, Klaus; Vieker, Jochen; von Wezyk, Alexander

    2016-10-01

    A new concept of a discharge based extreme ultraviolet radiation source is presented. This concept is based on an electrode system that consists of two consecutive pseudospark discharge stages. The first stage is used to create a pinch plasma as emitter in the extreme ultraviolet and soft X-ray range and the second stage is used as a high current switch between the storage capacity and the first stage. First results on the emission characteristics for the working gases nitrogen, krypton, and xenon, with focus on the emission at 2.88 nm, 6-7 nm, and around 13.5 nm, respectively, are disclosed under the aspect of the access to a larger discharge parameter range. It is shown that this increased range opens a path to a higher spectral peak brightness.

  3. Cytotoxic and mutagenic properties of shale oil byproducts. I. Activation of retort process waters with near ultraviolet light.

    PubMed

    Strniste, G F; Chen, D J

    1981-01-01

    Cultured Chinese hamster ovary (CHO) cells were exposed to dilutions of shale oil retort process waters obtained from three different retorting processes located in the Green River oil shale formations in the western part of the United States. Although the intensity of the response was dictated by thd process water used, all induced a cytotoxic (reduction in colony-forming ability) and mutagenic (induced at the hypoxanthine-guanine phosphoribosyl transferase (HGPRT) locus) response in cells pretreated with dilutions of the waters and subsequent exposure to near ultraviolet light (NUV). Combinations of process water plus NUV yielded mutation frequencies as great as 50% that witnessed for the mutation frequency induced by the potent carcinogen far ultraviolet light. NUV alone was nontoxic and nonmutagenic at the doses of radiation used. Exposure of CHO cells in the dark to nontoxic dilutions of the process waters resulted in small but significant increases in 6-thioguanine resistant mutants. (1-2 time background rates). The biological consequences resulting from the disposal of retort process waters into the delicate environment present in this oil shale region could be further complicated by this photoactivating process.

  4. Rapid diagnosis of sensitivity to ultraviolet light in fibroblasts from dermatologic disorders, with particular reference to xeroderma pigmentosum

    SciTech Connect

    Cleaver, J.E.; Thomas, G.H.

    1988-04-01

    A rapid and simple method for determining the sensitivity of human fibroblasts to ultraviolet light is described. As an alternative to the colony formation assay, this method can be used for the rapid diagnosis of ultraviolet light sensitivity in fibroblasts from photosensitive disorders. The method is based on growth of small numbers of cells in 1-cm wells of culture trays for 4 or more days after irradiation and determination of cell survival by the incorporation of (/sup 3/H)hypoxanthine. D37 values (the dose at which 37% of the control level of incorporation remains) obtained from this procedure showed the same relative sensitivity of normal and xeroderma pigmentosum fibroblasts as was obtained by colony formation. Untransformed and SV40-transformed fibroblasts, which have different growth rates and different responses to high cell densities, gave different D37 values by this assay in culture trays as compared with colony formation. Comparison of relative sensitivities to irradiation should therefore be made only between cell types with similar growth characteristics. The similar sensitivity of normal and xeroderma pigmentosum cells to mitomycin C was also determined by this culture tray method. By increasing cell density at the beginning of the experiments, a greater capacity of group C compared with group D fibroblasts for recovery from potentially lethal damage was also detected.

  5. Ultraviolet Light B-Mediated Inhibition of Skin Catalase Activity Promotes Gr-1+CD11b+ Myeloid Cell Expansion

    PubMed Central

    Sullivan, Nicholas J.; Tober, Kathleen L.; Burns, Erin M.; Schick, Jonathan S.; Riggenbach, Judith A.; Mace, Thomas A.; Bill, Matthew A.; Young, Gregory S.; Oberyszyn, Tatiana M.; Lesinski, Gregory B.

    2011-01-01

    Skin cancer incidence and mortality are higher in men compared to women, but the causes of this sex discrepancy remain largely unknown. Ultraviolet light exposure induces cutaneous inflammation and neutralizes cutaneous antioxidants. Gr-1+CD11b+ myeloid cells are heterogeneous bone marrow-derived cells that promote inflammation-associated carcinogenesis. Reduced activity of catalase, an antioxidant present within skin, has been associated with skin carcinogenesis. We utilized the outbred, immune competent Skh-1 hairless mouse model of ultraviolet light B (UVB)-induced inflammation and non-melanoma skin cancer to further define sex discrepancies in UVB-induced inflammation. Our results demonstrated that male skin had relatively lower baseline catalase activity, which was inhibited following acute UVB exposure in both sexes. Further analysis revealed that skin catalase activity inversely correlated with splenic Gr-1+CD11b+ myeloid cell percentage. Acute UVB exposure induced Gr-1+CD11b+ myeloid cell skin infiltration, which was inhibited to a greater extent in males by topical catalase treatment. In chronic UVB studies, we demonstrated that the percentage of splenic Gr-1+CD11b+ myeloid cells was 55% higher in male tumor-bearing mice compared to their female counterparts. Together, our findings indicate that lower skin catalase activity in male mice may at least in part contribute to increased UVB-induced Gr-1+CD11b+ myeloid cells and subsequent skin carcinogenesis. PMID:22030957

  6. Influence of saliva-coating on the ultraviolet-light-induced photocatalytic bactericidal effects on modified titanium surfaces

    NASA Astrophysics Data System (ADS)

    Lee, Jeong-Eun; Park, So-Yoon; Chang, Young-Il; Lim, Young-Jun; Ahn, Sug-Joon

    2012-07-01

    The purpose of this study was to investigate the ultraviolet-light-induced photocatalytic bactericidal effects of titanium surfaces on Streptococcus sanguinis in the presence of saliva-coating. Three different titanium disks were prepared: machined (MA), heat-treated (HT), and anodized surfaces (AO). Each disk was incubated with whole saliva or phosphate-buffered saline for 2 h. Antibacterial tests were performed by incubating a S. sanguinis suspension with each disk for 90 or 180 min under ultraviolet (UV) illumination. The viable counts of bacteria were enumerated from the cell suspension and the UV-light-induced photocatalytic bactericidal effects were determined by the bacterial survival rate. Without saliva-coating, AO disks exhibited significantly decreased bacterial survival rates compared to MA disks. The bacterial survival rates of the HT disks were intermediate between MA and AO in the absence of saliva-coating. However, saliva-coating significantly increased bacterial survival rates in all surface types. There was no significant difference in bacterial survival rates among the three surface types after saliva-coating. This study suggests that Ti-based antibacterial implant materials using TiO2 photocatalyst may have a limitation for intraoral use.

  7. Limb Observations of Solar Scattered Light by the Imaging Ultraviolet Spectrograph on MAVEN: New Constraints on Martian Mesospheric Cloud Variability

    NASA Astrophysics Data System (ADS)

    Stevens, Michael H.; Siskind, David E.; Evans, Scott; Schneider, Nicholas M.; Stewart, A. Ian F.; Deighan, Justin; Jain, Sonal Kumar; Crismani, Matteo; Stiepen, Arnaud; Chaffin, Michael S.; McClintock, William; Holsclaw, Gregory; Lefevre, Franck; Montmessin, Franck; Lo, Daniel; Clarke, John T.; Jakosky, Bruce

    2016-10-01

    The Imaging Ultraviolet Spectrograph (IUVS) on NASA's Mars Atmosphere and Volatile Evolution (MAVEN) mission observed the Martian upper atmosphere in late 2015 (Ls ~ 70) and early 2016 (Ls ~ 150). Although designed to measure the dayglow between 90-200 km IUVS also scans the limb down to 60 km, where solar scattered light dominates the mid-ultraviolet (MUV) signal. Occasionally, this MUV light shows enhanced scattering between 60-90 km indicating the presence of aerosols in the mesosphere. We quantify the solar scattering for each daylight scan obtained between October and December, 2015 and between April and June, 2016. We then identify over 100 scans of enhanced scattering between 60-90 km and assemble them both geographically and diurnally. The geographical distribution of the enhancements in 2015 is preferentially located near the equator, consistent with previous observations of mesospheric clouds for this part of the season. A wave three pattern in equatorial cloud occurrence suggests forcing from a non-migrating tide, possibly linked to the longitudinal variation of Mars surface topography. At the same time, there are indications of a diurnal variation such that the clouds seen in 2015 and 2016 are preferentially observed in the early morning, between 0600-0900 local solar time. This suggests an important role for a migrating temperature tide controlling the formation of Martian mesospheric clouds.

  8. Light-Absorbing Aerosol during NASA GRIP: Overview of Observations in the Free Troposphere and Associated with Tropical Storm Systems

    NASA Astrophysics Data System (ADS)

    Ziemba, L. D.; Beyersdorf, A. J.; Chen, G.; Corr, C. A.; Craig, L.; Dhaniyala, S.; Dibb, J. E.; Hudgins, C. H.; Ismail, S.; Latham, T.; Nenes, A.; Thornhill, K. L.; Winstead, E.; Anderson, B. E.

    2010-12-01

    Aerosols play a significant role in regulating Earth’s climate. Absorbing aerosols typically constitute a small fraction of ambient particle mass but can contribute significantly to direct and indirect climate forcing depending on size, mixing state, concentration, chemical composition, and vertical and spatial distribution. Aerosols may also significantly affect tropical storm/hurricane dynamics through direct light absorption and activation as cloud nuclei. An extensive suite of instrumentation measuring aerosol chemical, physical, and optical properties was deployed aboard the NASA DC-8 to characterize aerosol during the NASA GRIP (Genesis and Rapid Intensification Processes; August-September 2010) mission. The majority of flight time was spent at high altitude (greater than 9 km) and thus much of the sampling was done in the free troposphere, including extensive sampling in the vicinity of tropical storm systems and more diffuse cirrus clouds. With operations based in Fort Lauderdale, FL and St. Croix, U.S. Virgin Islands, a large geographic region was sampled including much of the Gulf of Mexico and tropical Atlantic Ocean. Observations are reported for light-absorbing carbon aerosol (mainly black carbon, BC) primarily using a single particle soot photometer (SP2). The SP2 employs single-particle laser-induced incandescence to provide a mass-specific measurement not subject to scattering interference that is optimal for the low concentration environments like those encountered during GRIP. BC mass concentrations, 100-500 nm size distributions, and mixing state (i.e. coating thickness of scattering material) are presented. Total and sub-micron aerosol absorption coefficients (principally from BC and dust aerosol) are reported using a particle soot absorption photometer (PSAP) along with comparisons with calculated absorption coefficients derived from SP2 observations in various conditions. In addition, dust aerosol is specifically identified using optical and

  9. Bioinformatic prediction of ultraviolet light mutagenesis sensitivity of human genes and a method for genetically engineering UVB resistance.

    PubMed

    Lease, Kevin A; Papageorgio, Chris

    2011-04-18

    Living on earth, we are exposed to ultraviolet (UV) light as part of the solar radiation. UVB spectrum light exposure contributes to the development of skin cancer by interacting with pyrimidine pairs to create lesions called cyclobutane pyrimidine dimers. If these lesions are not removed by nucleotide excision repair, they often give rise to C to T transition mutations. Based on these observations, a bioinformatics approach was used to predict the vulnerability of human protein coding genes to UVB induced loss of function mutations. This data was used to evaluate in depth those genes associated with malignant melanoma. In addition, we demonstrate a method of genetically engineering genes that significantly improves resistance to UVB loss of function mutations.

  10. Compact extreme ultraviolet reflectometer for the characterization of grazing incidence optics based on a gas discharge light source

    SciTech Connect

    Bergmann, Klaus; Rosier, Oliver; Metzmacher, Christof

    2005-04-01

    A grazing incidence reflectometer operating in the extreme ultraviolet (EUV) spectral range around 13.5 nm is presented which is making use of a compact xenon pinch plasma light source. The apparatus allows for measuring the absolute reflectivity of a sample for grazing incidence angle in the range from typically 5 deg. to 35 deg. by comparing the EUV diode signal for the reflected light and a reference diode with an accuracy of better than 2%. Design criteria for proper matching of diode apertures and distances with respect to the spatially extended plasma source are presented. The absolute accuracy has been checked by investigating a ruthenium sample with low roughness, which has a reflectivity in the EUV close to the theoretical limit. Comparison to measurements at the EUV-reflectometer of the Physikalisch Technische Bundesanstalt in Berlin at a synchrotron source confirm the absolute accuracy of better than 2% for the reflectivity for the angle interval of interest.

  11. Micronucleated erythrocytes in newborns of rat dams exposed to ultraviolet-A light during pregnancy; protection by ascorbic acid supplementation.

    PubMed

    Zúñiga-González, Guillermo M; Gómez-Meda, Belinda C; Zamora-Perez, Ana L; Martínez-González, María A; Muñoz de Haro, Ilse A; Pérez-Navarro, Adhoksaja E; Armendáriz-Borunda, Juan; Gallegos-Arreola, Martha P

    2015-04-01

    Pregnant hairless rat dams were exposed to ultraviolet-A light (UVA) to induce micronucleated erythrocytes (MNE) in their fetuses. The control group was exposed to conventional light; the experimental groups were exposed to UVA (365nm) during gestational days 16-21. In some cases, ascorbic acid (Asc) was administered in the drinking water from gestational day 15 until delivery. Dams were sampled at 48-h intervals during gestation, from day 16 until delivery. Blood was also obtained from neonates at birth; MNE, micronucleated polychromatic erythrocytes (MNPCE), and polychromatic erythrocytes (PCE) were scored. Increased MNE and MNPCE were observed in neonates born to mothers exposed to UVA for 40, 80 or 160min, compared to the control group. Asc treatment reduced MNE and MNPCE induction.

  12. Evidence for repair of ultraviolet light-damaged herpes virus in human fibroblasts by a recombination mechanism

    SciTech Connect

    Hall, J.D.; Featherston, J.D.; Almy, R.E.

    1980-09-01

    Human cells were either singly or multiply infected with herpes simplex virus (HSV-1) damaged by ultraviolet (uv) light, and the fraction of cells able to produce infectious virus was measured. The fraction of virus-producing cells was considerably greater for multiply infected cells than for singly infected cells at each uv dose examined. These high survival levels of uv-irradiated virus in multiply infected cells demonstrated that multiplicity-dependent repair, possibly due to genetic exchanges between damaged HSV-1 genomes, was occurring in these cells. To test whether uv light is recombinogenic for HSV-1, the effect of uv irradiation on the yield of temperature-resistant viral recombinants in cells infected with pairs of temperature-sensitive mutants was also investigated. The results of these experiments showed that the defective functions in these mutant host cells are not required for multiplicity-dependent repair or uv-stimulated viral recombination in herpes-infected cells.

  13. Linear behavior of a preformed microbubble containing light absorbing nanoparticles: insight from a mathematical model.

    PubMed

    Sassaroli, E; Li, K C P; O'Neill, B E

    2009-11-01

    Microbubbles are used as ultrasonic contrast agents in medical imaging because of their highly efficient scattering properties. Gold nanoparticles absorb specific wavelengths of optical radiation very effectively with the subsequent generation of thermo-acoustic waves in the surrounding medium. A theoretical and numerical analysis of the possibility of inducing radial oscillations in a pre-existing spherical microbubble, through the laser excitation of gold nanoparticles contained within, is presented. A description of such a system can be obtained in terms of a confined two-phase model, with the nanoparticles suspended in a confined region of gas, surrounded by a liquid. The Rayleigh-Plesset equation is assumed to be valid at the boundary between the gas and the liquid. The confined two-phase model is solved in linear approximation. The system is diagonalized and the general solution is obtained. This solution is in the form of exponentially decaying oscillatory functions for the temperature and pressure inside the bubble, and radial oscillations of the bubble boundary. It was found that, for the right size of bubbles, the oscillatory behavior takes place in the low megahertz range, which is ideal for medical applications. This study suggests the possibility of new applications of microbubbles in photoacoustic imaging.

  14. Phototactic responses to ultraviolet and white light in various species of Collembola, including the eyeless species, Folsomia candida.

    PubMed

    Fox, Gregory L; Coyle-Thompson, Catherine A; Bellinger, Peter F; Cohen, Randy W

    2007-01-01

    Previous observations have indicated homology in the cellular components between Collembolan eyes and the compound eyes of insects. However, behavioral or physiological studies indicating similarities in function are lacking. Collembolan eyes were examined from three species in the Family Isotomidae using scanning electron microscopy. Collembolan eyes are arranged dorsally and laterally on each side of the head in two species, Proisotoma minuta with eight eyes on each side of the head and Folsomia similis with one eye on each side of the head. In both of these species the eyes were located just posterior to the postantennal organ. In Folsomia candida, no external eye structures were detected. These three species were assayed for a series of behavioral preferences using ultraviolet (UV), white light and dark, and temperature conditions. The tests demonstrated that over 76% of all three species, including the eyeless F. Candida, chose white over UV light, over 69% preferred dark over UV, and over 77% favored dark over white light. The results demonstrated that all three species detect both UV and white light and avoid it, preferring cool, dark habitats. From the results of this study, it is hypothesized that F. candida may, in fact, be only "lensless" and may be able to detect light by having internal, non-ocular photoreceptors. Further histological studies are needed to investigate this possibility.

  15. Diurnal and developmental changes in energy allocation of absorbed light at PSII in field-grown rice.

    PubMed

    Ishida, Satoshi; Uebayashi, Nozomu; Tazoe, Youshi; Ikeuchi, Masahiro; Homma, Koki; Sato, Fumihiko; Endo, Tsuyoshi

    2014-01-01

    The allocation of absorbed light energy in PSII to electron transport and heat dissipation processes in rice grown under waterlogged conditions was estimated with the lake model of energy transfer. With regard to diurnal changes in energy allocation, the peak of the energy flux to electron transport, J(PSII), occurred in the morning and the peak of the energy flux to heat dissipation associated with non-photochemical quenching of Chl fluorescence, J(NPQ), occurred in the afternoon. With regard to seasonal changes in energy allocation, J(PSII) in the rapidly growing phase was greater than that in the ripening phase, even though the leaves of rice receive less light in the growing phase than in the ripening period in Japan. This seasonal decrease in J(PSII) was accompanied by an increase in J(NPQ). One of the reasons for the lower J(PSII) in the ripening phase might be a more sever afternoon suppression of J(PSII). To estimate energy dissipation due to photoinhibition of PSII, J(NPQ) was divided into J(fast), which is associated with fast-recovering NPQ mainly due to qE, and J(slow), which is mainly due to photoinhibition. The integrated daily energy loss by photoinhibiton was calculated to be about 3-8% of light energy absorption in PSII. Strategies for the utilization of light energy adopted by rice are discussed. For example, very efficient photosynthesis under non-saturating light in the rapidly growing phase is proposed.

  16. Instrumentation and method for measuring NIR light absorbed in tissue during MR imaging in medical NIRS measurements

    NASA Astrophysics Data System (ADS)

    Myllylä, Teemu S.; Sorvoja, Hannu S. S.; Nikkinen, Juha; Tervonen, Osmo; Kiviniemi, Vesa; Myllylä, Risto A.

    2011-07-01

    Our goal is to provide a cost-effective method for examining human tissue, particularly the brain, by the simultaneous use of functional magnetic resonance imaging (fMRI) and near-infrared spectroscopy (NIRS). Due to its compatibility requirements, MRI poses a demanding challenge for NIRS measurements. This paper focuses particularly on presenting the instrumentation and a method for the non-invasive measurement of NIR light absorbed in human tissue during MR imaging. One practical method to avoid disturbances in MR imaging involves using long fibre bundles to enable conducting the measurements at some distance from the MRI scanner. This setup serves in fact a dual purpose, since also the NIRS device will be less disturbed by the MRI scanner. However, measurements based on long fibre bundles suffer from light attenuation. Furthermore, because one of our primary goals was to make the measuring method as cost-effective as possible, we used high-power light emitting diodes instead of more expensive lasers. The use of LEDs, however, limits the maximum output power which can be extracted to illuminate the tissue. To meet these requirements, we improved methods of emitting light sufficiently deep into tissue. We also show how to measure NIR light of a very small power level that scatters from the tissue in the MRI environment, which is characterized by strong electromagnetic interference. In this paper, we present the implemented instrumentation and measuring method and report on test measurements conducted during MRI scanning. These measurements were performed in MRI operating rooms housing 1.5 Tesla-strength closed MRI scanners (manufactured by GE) in the Dept. of Diagnostic Radiology at the Oulu University Hospital.

  17. Ultraviolet absorption hygrometer

    DOEpatents

    Gersh, Michael E.; Bien, Fritz; Bernstein, Lawrence S.

    1986-01-01

    An ultraviolet absorption hygrometer is provided including a source of pulsed ultraviolet radiation for providing radiation in a first wavelength region where water absorbs significantly and in a second proximate wavelength region where water absorbs weakly. Ultraviolet radiation in the first and second regions which has been transmitted through a sample path of atmosphere is detected. The intensity of the radiation transmitted in each of the first and second regions is compared and from this comparison the amount of water in the sample path is determined.

  18. Ultraviolet absorption hygrometer

    DOEpatents

    Gersh, M.E.; Bien, F.; Bernstein, L.S.

    1986-12-09

    An ultraviolet absorption hygrometer is provided including a source of pulsed ultraviolet radiation for providing radiation in a first wavelength region where water absorbs significantly and in a second proximate wavelength region where water absorbs weakly. Ultraviolet radiation in the first and second regions which has been transmitted through a sample path of atmosphere is detected. The intensity of the radiation transmitted in each of the first and second regions is compared and from this comparison the amount of water in the sample path is determined. 5 figs.

  19. Light-Induced Spectral Absorbance Changes in Relation to Photosynthesis and the Epoxidation State of Xanthophyll Cycle Components in Cotton Leaves 1

    PubMed Central

    Bilger, Wolfgang; Björkman, Olle; Thayer, Susan S.

    1989-01-01

    When cotton (Gossypium hirsutum L., cv Acaia SJC-1) leaves kept in weak light were suddenly exposed to strong red actinic light a spectral absorbance change took place having the following prominent characteristics. (a) It was irreversible within the first four minute period after darkening. (b) The difference in leaf absorbance between illuminated and predarkened leaves had a major peak at 505 nanometers, a minor peak at 465 nanometers, a shoulder around 515 nanometers, and minor troughs at 455 and 480 nanometers. (c) On the basis of its spectral and kinetic characteristics this absorbance change can be readily distinguished from the much faster electrochromic shift which has a peak at 515 nanometers, from the slow, so-called light-scattering change which has a broad peak centered around 535 nanometers and is reversed upon darkening, and from absorbance changes associated with light-induced chloroplast rearrangements. (d) The extent and time course of this absorbance change closely matched that of the deepoxidation of violaxanthin to zeaxanthin in the same leaves. (e) Both the absorbance change and the ability to form zeaxanthin were completely blocked in leaves to which dithiothreitol (DTT) had been provided through the cut petlole. DTT treatment also caused strong inhibition of that component of the 535-nanometer absorbance change which is reversed in less than 4 minutes upon darkening and considered to be caused by increased light scattering. Moreover, DTT inhibited a large part of nonphotochemical quenching of chlorophyll fluorescence in the presence of excessive light. However, DTT had no detectable effect on the photon yield of photosynthesis measured under strictly rate-limiting photon flux densities or on the light-saturated photosynthetic capacity, at least in the short term. We conclude that it is possible to monitor light-induced violaxanthin de-epoxidation in green intact leaves by measurement of the absorbance change at 505 nanometers. Determination

  20. Ultraviolet light stable and transparent sol-gel methyl siloxane hybrid material for UV light-emitting diode (UV LED) encapsulant.

    PubMed

    Bae, Jun-Young; Kim, YongHo; Kim, HweaYoon; Kim, YuBae; Jin, Jungho; Bae, Byeong-Soo

    2015-01-21

    An ultraviolet (UV) transparent and stable methyl-siloxane hybrid material was prepared by a facile sol-gel method. The transparency and stability of a UV-LED encapsulant is an important issue because it affects UV light extraction efficiency and long-term reliability. We introduced a novel concept for UV-LED encapsulation using a thermally curable oligosiloxane resin. The encapsulant was fabricated by a hydrosilylation of hydrogen-methyl oligosiloxane resin and vinyl-methyl siloxane resin, and showed a comparable transmittance to polydimethylsiloxane (PDMS) in the UVB (∼300 nm) region. Most remarkably, the methyl-siloxane hybrid materials exhibited long-term UV stability under light soaking in UVB (∼300 nm) for 1000 h.

  1. Seasonal variations in the light-absorbing properties of water-soluble and insoluble organic aerosols in Seoul, Korea

    NASA Astrophysics Data System (ADS)

    Kim, Hwajin; Kim, Jin Young; Jin, Hyoun Cher; Lee, Ji Yi; Lee, Se Pyo

    2016-03-01

    The spectral properties of light-absorbing organic aerosol extractions were investigated using 24-h average fine particulate matter (PM2.5) measurements from October 2012 to September 2013 in Seoul, Korea. The light-absorption spectra of water and methanol extracts exhibited strong evidence of brown carbon with Absorption Angstrom Exponent (AAE; fitted between 300 and 700 nm) ranges of 5.84-9.17 and 4.08-5.75, with averages of 7.23 ± 1.58 and 5.05 ± 0.67, respectively. The light absorption of both extracts at 365 nm (Abs365), which is typically used as a proxy for brown carbon (BrC), displayed strong seasonal variations and was well correlated with both water-soluble organic carbon (WSOC; r = 0.81) and organic carbon (OC; r = 0.85), indicating that both primary and secondary organics were sources of BrC in this region. Normalizing the Abs365 of water and methanol extracts to the mass of WSOC and OC yielded average solution mass absorption efficiency (MAE365) of 0.28-1.18 and 0.44-1.45 m2 g-1 C, respectively. MAE365 in Korea were in the same range or slightly lower than those in China, however, despite the same ranges, the seasonal variations were different, suggesting that the sources of light absorbers could be different. Combining the AAE, Abs365, and MAE365 of both extracts and a detailed chemical speciation of filter extracts identified the compounds responsible for the temporal variations of BrC in Korea. During summer, secondary organic aerosol (SOA), photochemically generated from anthropogenic emissions, was the major source; however, during winter, long range transported organics or transported BrC seem to be a source of BrC in Korea, a downwind site of China, where severe smog and BrC were observed during this season. Biomass burning was also an important source; however, unlike in previous studies, where it was identified as a major source during winter, here, it contributed during the whole year. Although many of its properties, sources, and potential

  2. A Second Ultraviolet ``Light Bulb'' behind the Supernova Remnant SN 1006

    NASA Astrophysics Data System (ADS)

    Winkler, P. Frank; Long, Knox S.

    1997-09-01

    A point X-ray source located 9' NE of the center of SN 1006 has been spectroscopically identified as a background QSO, with a redshift of 0.335. The object is moderately bright, with magnitude V = 18.3. If its ultraviolet spectrum is typical of low-z quasars, this object will be a second source (after the Schweizer-Middleditch star) to use for absorption spectroscopy of material within SN 1006. Absorption spectra provide a unique probe for unshocked ejecta within this supernova remnant and can possibly solve the long-standing problem of ``missing'' iron in the remnants of Type Ia supernovae.

  3. Direct writing of ferroelectric domains on strontium barium niobate crystals using focused ultraviolet laser light

    SciTech Connect

    Boes, Andreas; Crasto, Tristan; Steigerwald, Hendrik; Mitchell, Arnan; Wade, Scott; Frohnhaus, Jakob; Soergel, Elisabeth

    2013-09-30

    We report ferroelectric domain inversion in strontium barium niobate (SBN) single crystals by irradiating the surface locally with a strongly focused ultraviolet (UV) laser beam. The generated domains are investigated using piezoresponse force microscopy. We propose a simple model that allows predicting the domain width as a function of the irradiation intensity, which indeed applies for both SBN and LiNbO{sub 3}. Evidently, though fundamentally different, the domain structure of both SBN and LiNbO{sub 3} can be engineered through similar UV irradiation.

  4. 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.

  5. Note: Three wavelengths near-infrared spectroscopy system for compensating the light absorbance by water

    NASA Astrophysics Data System (ADS)

    Bhutta, M. Raheel; Hong, Keum-Shik; Kim, Beop-Min; Hong, Melissa Jiyoun; Kim, Yun-Hee; Lee, Se-Ho

    2014-02-01

    Given that approximately 80% of blood is water, we develop a wireless functional near-infrared spectroscopy system that detects not only the concentration changes of oxy- and deoxy-hemoglobin (HbO and HbR) during mental activity but also that of water (H2O). Additionally, it implements a water-absorption correction algorithm that improves the HbO and HbR signal strengths during an arithmetic task. The system comprises a microcontroller, an optical probe, tri-wavelength light emitting diodes, photodiodes, a WiFi communication module, and a battery. System functionality was tested by means of arithmetic-task experiments performed by healthy male subjects.

  6. Note: three wavelengths near-infrared spectroscopy system for compensating the light absorbance by water.

    PubMed

    Bhutta, M Raheel; Hong, Keum-Shik; Kim, Beop-Min; Hong, Melissa Jiyoun; Kim, Yun-Hee; Lee, Se-Ho

    2014-02-01

    Given that approximately 80% of blood is water, we develop a wireless functional near-infrared spectroscopy system that detects not only the concentration changes of oxy- and deoxy-hemoglobin (HbO and HbR) during mental activity but also that of water (H2O). Additionally, it implements a water-absorption correction algorithm that improves the HbO and HbR signal strengths during an arithmetic task. The system comprises a microcontroller, an optical probe, tri-wavelength light emitting diodes, photodiodes, a WiFi communication module, and a battery. System functionality was tested by means of arithmetic-task experiments performed by healthy male subjects.

  7. Time-resolved electroluminescence studies of III-nitride ultraviolet photonic-crystal light-emitting diodes

    NASA Astrophysics Data System (ADS)

    Shakya, J.; Lin, J. Y.; Jiang, H. X.

    2004-09-01

    Transient responses of III-nitride photonic-crystal (PC) ultraviolet (UV) light-emitting diodes (LEDs) were measured by picosecond time-resolved electroluminescence (EL) spectroscopy. Triangular arrays of PCs with different diameters/periodicities were fabricated on 333nmUV LEDs for enhancing light extraction efficiency using electron-beam lithography and inductively coupled-plasma dry etching. With the incorporation of PCs on LEDs, the EL decay time constant τ decreases systematically with the increase of the etched sidewall area indicating the strong effect of the surface recombination. The surface recombination velocities on the p-type epitaxial surface and on the sidewall of etched holes on LEDs were determined to be 1.73×104cm /s and 1.48×105cm/s, respectively. The angular distribution of light emission from LEDs with PCs shows slight narrowing in far-field pattern. Because of the increased transient response along with enhanced light extraction, the incorporation of PCs in UV LEDs provide an effective method to control the modulation speed of UV LEDs, which could be very useful for many applications.

  8. Improved output power of GaN-based ultraviolet light-emitting diodes with sputtered AlN nucleation layer

    NASA Astrophysics Data System (ADS)

    Chiu, C. H.; Lin, Y. W.; Tsai, M. T.; Lin, B. C.; Li, Z. Y.; Tu, P. M.; Huang, S. C.; Hsu, Earl; Uen, W. Y.; Lee, W. I.; Kuo, H. C.

    2015-03-01

    In this work, the ultraviolet light-emitting diodes (UV-LEDs) at 380 nm were grown on patterned sapphire substrate (PSS) by atmospheric pressure metal organic chemical vapor deposition (AP-MOCVD). A sputtered AlN nucleation layer was utilized on the PSS to enhance the quality of the epitaxial layer. By using high-resolution X-ray diffraction, the full-width at half-maximum of the rocking curve shows that the UV-LEDs with sputtered AlN nucleation layer had better crystalline quality when compared to conventional GaN nucleation samples. From the scanning electron microscope (SEM) and transmission electron microscopy (TEM) images, it can be observed that the tip and sidewall portion of the pattern was smooth using the sputtered AlN nucleation layer. The threading dislocation densities (TDDs) are reduced from 6×107 cm-2 to 2.5×107 cm-2 at the interface between the u-GaN layers for conventional and AlN PSS devices, respectively. As a result, a much higher light output power was achieved. The light output power at an injection current of 20 mA was enhanced by 30%. Further photoluminescence (PL) measurement and numerical simulation confirm that this increase of output power can be attributed to the improvement of material quality and light extraction.

  9. Optimizing laser produced plasmas for efficient extreme ultraviolet and soft X-ray light sources

    SciTech Connect

    Sizyuk, Tatyana; Hassanein, Ahmed

    2014-08-15

    Photon sources produced by laser beams with moderate laser intensities, up to 10{sup 14 }W/cm{sup 2}, are being developed for many industrial applications. The performance requirements for high volume manufacture devices necessitate extensive experimental research supported by theoretical plasma analysis and modeling predictions. We simulated laser produced plasma sources currently being developed for several applications such as extreme ultraviolet lithography using 13.5% ± 1% nm bandwidth, possibly beyond extreme ultraviolet lithography using 6.× nm wavelengths, and water-window microscopy utilizing 2.48 nm (La-α) and 2.88 nm (He-α) emission. We comprehensively modeled plasma evolution from solid/liquid tin, gadolinium, and nitrogen targets as three promising materials for the above described sources, respectively. Results of our analysis for plasma characteristics during the entire course of plasma evolution showed the dependence of source conversion efficiency (CE), i.e., laser energy to photons at the desired wavelength, on plasma electron density gradient. Our results showed that utilizing laser intensities which produce hotter plasma than the optimum emission temperatures allows increasing CE for all considered sources that, however, restricted by the reabsorption processes around the main emission region and this restriction is especially actual for the 6.× nm sources.

  10. Radiation hardness of AlxGa1-xN photodetectors exposed to Extreme UltraViolet (EUV) light beam

    NASA Astrophysics Data System (ADS)

    Malinowski, Pawel E.; John, Joachim; Barkusky, Frank; Duboz, Jean Yves; Lorenz, Anne; Cheng, Kai; Derluyn, Joff; Germain, Marianne; De Moor, Piet; Minoglou, Kyriaki; Bayer, Armin; Mann, Klaus; Hochedez, Jean-Francois; Giordanengo, Boris; Borghs, Gustaaf; Mertens, Robert

    2009-05-01

    We report on the results of fabrication and optoelectrical characterization of Gallium Nitride (GaN) based Extreme UltraViolet (EUV) photodetectors. Our devices were Schottky photodiodes with a finger-shaped rectifying contact, allowing better penetration of light into the active region. GaN layers were epitaxially grown on Silicon (111) by Metal- Organic-Chemical Vapor Deposition (MOCVD). Spectral responsivity measurements in the Near UltraViolet (NUV) wavelength range (200-400 nm) were performed to verify the solar blindness of the photodetectors. After that the devices were exposed to the EUV focused beam of 13.5 nm wavelength using table-top EUV setup. Radiation hardness was tested up to a dose of 3.3Â.1019 photons/cm2. Stability of the quantum efficiency was compared to the one measured in the same way for a commercially available silicon based photodiode. Superior behavior of GaN devices was observed at the wavelength of 13.5 nm.

  11. Crash compatibility between cars and light trucks: benefits of lowering front-end energy-absorbing structure in SUVs and pickups.

    PubMed

    Baker, Bryan C; Nolan, Joseph M; O'Neill, Brian; Genetos, Alexander P

    2008-01-01

    Passenger vehicles are designed to absorb crash energy in frontal crashes through deformation or crush of energy-absorbing structures forward of the occupant compartment. In collisions between cars and light trucks (i.e., pickups and SUVs), however, the capacity of energy-absorption structures may not be fully utilized because mismatches often exist between the heights of these structures in the colliding vehicles. In 2003 automakers voluntarily committed to new design standards aimed at reducing the height mismatches between cars and light trucks. By September 2009 all new light trucks will have either the primary front structure (typically the frame rails) or a secondary structure connected to the primary structure low enough to interact with the primary structures in cars, which for most cars is about the height of the front bumper. To estimate the overall benefit of the voluntary commitment, the real-world crash experience of light trucks already meeting the height-matching criteria was compared with that of light trucks not meeting the criteria for 2000-2003 model light trucks in collisions with passenger cars during calendar years 2001-2004. The estimated benefits of lower front energy-absorbing structure were a 19 percent reduction (p<0.05) in fatality risk to belted car drivers in front-to-front crashes with light trucks and a 19 percent reduction (p<0.05) in fatality risk to car drivers in front-to-driver-side crashes with light trucks.

  12. Electrochemically synthesized visible light absorbing vertically aligned N-doped TiO{sub 2} nanotube array films

    SciTech Connect

    Antony, Rajini P.; Mathews, Tom; Ajikumar, P.K.; Krishna, D. Nandagopala; Dash, S.; Tyagi, A.K.

    2012-12-15

    Graphical abstract: Display Omitted Highlights: ► Single step electrochemical synthesis of N-doped TiO{sub 2} nanotube array films. ► Effective substitutional N-doping achieved. ► Different N-concentrations were achieved by varying the N-precursor concentration in the electrolyte. ► Visible light absorption observed at high N-doping. -- Abstract: Visible light absorbing vertically aligned N-doped anatase nanotube array thin films were synthesized by anodizing Ti foils in ethylene glycol + NH{sub 4}F + water mixture containing urea as nitrogen source. Different nitrogen concentrations were achieved by varying the urea content in the electrolyte. The structure, morphology, composition and optical band gap of the nanotube arrays were determined by X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy (XPS) and diffuse reflectance spectroscopy, respectively. The substitution of O{sup 2−} ions by N{sup 3−} ions in the anion sublattice as well as the formulae of the doped samples was confirmed from the results of XPS. The optical band gap of the nanotube arrays was found to decrease with N-concentration. The sample with the highest concentration corresponding to the formula TiO{sub 1.83}N{sub 0.14} showed two regions in the Tauc's plot indicating the presence of interband states.

  13. Optoacoustic spectroscopy for real-time monitoring of strongly light-absorbing solutions in applications to analytical chemistry.

    PubMed

    Filimonova, Tatyana A; Volkov, Dmitry S; Proskurnin, Mikhail A; Pelivanov, Ivan M

    2013-12-01

    An optoacoustic technique for solutions of strongly light-absorbing analytes at 0.1-0.01 mol l(-1) is proposed. The technique is based on the wide-band forward mode detection of temporal profiles of laser-generated ultrasonic pulses (optoacoustic signals). The leading edge of the signal repeats the distribution of the laser fluence in the medium, which makes it possible to determine its optical absorption and investigate its dynamics during a reaction. The range of light-absorption coefficients starts from 1 to 5 and reaches 10(4) to 10(5) cm(-1). The determination of iron(II) as ferroin shows the possibility of probing 0.1 mol l(-1) of iron(II), which was not previously achieved for this reaction by optical spectroscopy. To further prove the concept, kinetic measurements for ferroin decomposition at the level of 0.1 mol l(-1) and at high pHs are performed. The results are compared with spectrophotometry at lower concentrations and show good reproducibility and accuracy of kinetic constants.

  14. Optoacoustic spectroscopy for real-time monitoring of strongly light-absorbing solutions in applications to analytical chemistry☆

    PubMed Central

    Filimonova, Tatyana A.; Volkov, Dmitry S.; Proskurnin, Mikhail A.; Pelivanov, Ivan M.

    2013-01-01

    An optoacoustic technique for solutions of strongly light-absorbing analytes at 0.1–0.01 mol l−1 is proposed. The technique is based on the wide-band forward mode detection of temporal profiles of laser-generated ultrasonic pulses (optoacoustic signals). The leading edge of the signal repeats the distribution of the laser fluence in the medium, which makes it possible to determine its optical absorption and investigate its dynamics during a reaction. The range of light-absorption coefficients starts from 1 to 5 and reaches 104 to 105 cm−1. The determination of iron(II) as ferroin shows the possibility of probing 0.1 mol l−1 of iron(II), which was not previously achieved for this reaction by optical spectroscopy. To further prove the concept, kinetic measurements for ferroin decomposition at the level of 0.1 mol l−1 and at high pHs are performed. The results are compared with spectrophotometry at lower concentrations and show good reproducibility and accuracy of kinetic constants. PMID:25302150

  15. Effect of Morphology Control of Light Absorbing Layer on CH3NH3PbI3 Perovskite Solar Cells.

    PubMed

    Lei, Binglong; Eze, Vincent Obiozo; Mori, Tatsuo

    2016-04-01

    As one of the most significant components of perovskite solar cells, the perovskite light absorbing layer demands high quality to guarantee extraordinary power conversion efficiency (PCE). We have fabricated series of CH3NH3PbI3 perovskite solar cells by virtue of gas-flowing assisting (GFA), spin coating twice for the Pbl2 layer and dipping the semi-samples in a thermal CH3NH3I solution, by which some undesirable perovskite morphologies can be effectively avoided. The modified conductions have also dramatically improved the perovskite layer and elevated the coverage ratio from 53.6% to 79.5%. All the fabrication processes, except the steps for deposition of the hole transport material (HTM) and back gold electrode, have been conducted in air and an average PCE of 6.6% has been achieved by initiatively applying N,N'-bis(1-naphtyl)-N,N'-diphenyl-1,1'-biphenyl-4,4'-diamine (α-NPD) doped by MoO3 as HTM. The CH3NH3PbI3 perovskite's morphology and its coverage ratio to the underneath TiO2 mesoporic layer are evaluated to account for the cells' performance. It has demonstrated that higher homogeneity and coverage ratio of the CH3NH3PbI3 layer have most significantly contributed to the solar cells' light conversion efficiency. Keywords: Perovskite, Solar Cell, Morphology, Coverage Ratio, Hole Transport Material.

  16. Identification of light absorbing oligomers from glyoxal and methylglyoxal aqueous processing: a comparative study at the molecular level

    NASA Astrophysics Data System (ADS)

    Finessi, Emanuela; Hamilton, Jacqueline; Rickard, Andrew; Baeza-Romero, Maria; Healy, Robert; Peppe, Salvatore; Adams, Tom; Daniels, Mark; Ball, Stephen; Goodall, Iain; Monks, Paul; Borras, Esther; Munoz, Amalia

    2014-05-01

    Numerous studies point to the reactive uptake of gaseous low molecular weight carbonyls onto atmospheric waters (clouds/fog droplets and wet aerosols) as an important SOA formation route not yet included in current models. However, the evaluation of these processes is challenging because water provides a medium for a complex array of reactions to take place such as self-oligomerization, aldol condensation and Maillard-type browning reactions in the presence of ammonium salts. In addition to adding to SOA mass, aqueous chemistry products have been shown to include light absorbing, surface-active and high molecular weight oligomeric species, and can therefore affect climatically relevant aerosol properties such as light absorption and hygroscopicity. Glyoxal (GLY) and methylglyoxal (MGLY) are the gaseous carbonyls that have perhaps received the most attention to date owing to their ubiquity, abundance and reactivity in water, with the majority of studies focussing on bulk physical properties. However, very little is known at the molecular level, in particular for MGLY, and the relative potential of these species as aqueous SOA precursors in ambient air is still unclear. We have conducted experiments with both laboratory solutions and chamber-generated particles to simulate the aqueous processing of GLY and MGLY with ammonium sulphate (AS) under typical atmospheric conditions and investigated their respective aging products. Both high performance liquid chromatography coupled with UV-Vis detection and ion trap mass spectrometry (HPLC-DAD-MSn) and high resolution mass spectrometry (FTICRMS) have been used for molecular identification purposes. Comprehensive gas chromatography with nitrogen chemiluminescence detection (GCxGC-NCD) has been applied for the first time to these systems, revealing a surprisingly high number of nitrogen-containing organics (ONs), with a large extent of polarities. GCxGC-NCD proved to be a valuable tool to determine overall amount and rates of

  17. Estimation of diffuse attenuation of ultraviolet light in optically shallow Florida Keys waters from MODIS measurements

    EPA Science Inventory

    Diffuse attenuation of solar light (Kd, m−1) determines the percentage of light penetrating the water column and available for benthic organisms. Therefore, Kd can be used as an index of water quality for coastal ecosystems that are dependent on photosynthesis, such as the coral ...

  18. Advantages of AlGaN-based deep ultraviolet light-emitting diodes with a superlattice electron blocking layer

    NASA Astrophysics Data System (ADS)

    Sun, Pai; Bao, Xianglong; Liu, Songqing; Ye, Chunya; Yuan, Zhaorong; Wu, Yukun; Li, Shuping; Kang, Junyong

    2015-09-01

    The properties of 298 nm AlGaN based deep ultraviolet light-emitting diodes (UV LEDs) with different Al mole compositions in the conventional electron blocking layer (EBL) are discussed in this paper, the optimal Al mole composition of the conventional EBL is identified at 0.8. The improved structure with an AlGaN/AlGaN superlattice (SL) electron blocking layer (EBL) was then investigated numerically. The electrical and optical properties, band diagrams, carrier concentrations, radiative recombination rates and internal quantum efficiency (IQE) were investigated by APSYS software, and results show that the deep UV LED with superlattice EBL performed much better than the conventional EBL deep UV LED, attributed to reduced electrons leakage and increased holes injection.

  19. Size and frequency of gaps in newly synthesized DNA of xeroderma pigmentosum human cells irradiated with ultraviolet light

    SciTech Connect

    Meneghini, R.; Cordeiro-Stone, M.; Schumacher, R.I.

    1981-01-01

    Native newly synthesized DNA from human cells (xeroderma pigmentosum type) irradiated with ultraviolet light releases short pieces of DNA (L-DNA) when incubated with the single-strand specific S/sub 1/ nuclease. This is not observed in the case of unirradiated cells. Previous experiments had shown that the L-DNA resulted from the action of S/sub 1/ nuclease upon gaps, i.e., single-stranded DNA discontinuities in larger pieces of double-stranded DNA. We verified that the duplex L-DNA, that arises from the inter-gap regions upon S/sub 1/ nuclease treatment, has a size which approximates the distance between two pyrimidine dimers on the same strand. A method was devised to measure the size of the gaps. These parameters have been considered in the proposition of a model for DNA synthesis on a template containing pyrimidine dimers.

  20. High efficiency single Ag nanowire/p-GaN substrate Schottky junction-based ultraviolet light emitting diodes

    SciTech Connect

    Wu, Y.; Li, X.; Xu, P.; Wang, Y.; Shen, X.; Liu, X.; Yang, Q.; Hasan, T.

    2015-02-02

    We report a high efficiency single Ag nanowire (NW)/p-GaN substrate Schottky junction-based ultraviolet light emitting diode (UV-LED). The device demonstrates deep UV free exciton electroluminescence at 362.5 nm. The dominant emission, detectable at ultralow (<1 μA) forward current, does not exhibit any shifts when the forward current is increased. External quantum efficiency (EQE) as high as 0.9% is achieved at 25 μA current at room temperature. Experiments and simulation analysis show that devices fabricated with thinner Ag NWs have higher EQE. However, for very thin Ag NWs (diameter < 250 nm), this trend breaks down due to heat accumulation in the NWs. Our simple device architecture offers a potentially cost-effective scheme to fabricate high efficiency Schottky junction-based UV-LEDs.

  1. Tunable diffraction grating using ultraviolet-light-induced spatial phase modulation in dual-frequency liquid crystal

    SciTech Connect

    Lin, P.-T.; Liang Xiao; Ren Hongwen; Wu, S.-T.

    2004-08-16

    An electrically tunable diffraction phase grating using ultraviolet (UV)-light-induced spatial dielectric modulation of a dual-frequency liquid crystal (DFLC) cell is demonstrated. A photomask with transparent and opaque stripes was used for fabricating the grating. In the UV-exposed stripes, the negative dielectric anisotropy ({delta}{epsilon}) tolane compound of the DFLC mixture is partially polymerized resulting in a decreased threshold voltage as compared to that of the unexposed region. Upon applying a constant voltage, the phase difference between the adjacent pixels is produced. The first-order diffraction efficiency reaches {approx}60% which agrees well with the simulation results. Due to the dual-frequency addressing at 30 V{sub rms}, the response time of the DFLC phase grating was measured to be {approx}1 ms at room temperature.

  2. Molecular beam epitaxial growth and characterization of Al(Ga)N nanowire deep ultraviolet light emitting diodes and lasers

    NASA Astrophysics Data System (ADS)

    Mi, Z.; Zhao, S.; Woo, S. Y.; Bugnet, M.; Djavid, M.; Liu, X.; Kang, J.; Kong, X.; Ji, W.; Guo, H.; Liu, Z.; Botton, G. A.

    2016-09-01

    We report on the detailed molecular beam epitaxial growth and characterization of Al(Ga)N nanowire heterostructures on Si and their applications for deep ultraviolet light emitting diodes and lasers. The nanowires are formed under nitrogen-rich conditions without using any metal catalyst. Compared to conventional epilayers, Mg-dopant incorporation is significantly enhanced in nearly strain- and defect-free Al(Ga)N nanowire structures, leading to efficient p-type conduction. The resulting Al(Ga)N nanowire LEDs exhibit excellent performance, including a turn-on voltage of ∼5.5 V for an AlN nanowire LED operating at 207 nm. The design, fabrication, and performance of an electrically injected AlGaN nanowire laser operating in the UV-B band is also presented.

  3. High-output-power 255/280/310 nm deep ultraviolet light-emitting diodes and their lifetime characteristics

    NASA Astrophysics Data System (ADS)

    Fujioka, A.; Asada, K.; Yamada, H.; Ohtsuka, T.; Ogawa, T.; Kosugi, T.; Kishikawa, D.; Mukai, T.

    2014-06-01

    255/280/310 nm deep ultraviolet light-emitting diodes (DUV LEDs) suitable for high-current operation are reported. Newly developed 1 mm sized chips are installed in a commercial package with a two-series configuration. At a forward current of 350 mA, we measured powers of 45.2, 93.3, and 65.8 mW for the 255, 280, and 310 nm LEDs, respectively. The corresponding external quantum efficiencies per serial circuit were 1.3, 3.0, and 2.4%, and successful chip scalability was demonstrated. The 50% lifetime of the 280 nm LED die was estimated to be 3000 h at a junction temperature of 30 °C.

  4. Effects of ultraviolet light (315 nm), temperature and relative humidity on the degradation of polylactic acid plastic films.

    PubMed

    Copinet, Alain; Bertrand, Celine; Govindin, Stephanie; Coma, Veronique; Couturier, Yves

    2004-05-01

    The influence of temperature (30, 45 and 60 degrees C) and relative humidity (RH) (30%, 50% and 100%) on the degradation of poly(l-lactic acid) (PLA) films were studied. In addition, the effects of ultraviolet (UV) light (315 nm) on the degradation of PLA films were also analyzed. Various analytical techniques were applied to observe changes in the properties of PLA polymer films. FTIR spectroscopy was used as semi-quantitative method to get information about the chemistry of the degradative process. The degradation rate of PLA was enhanced by increasing temperature and RH, factors responsible for a faster reduction of the weight-average molecular weight (M(W)), of the glass transition temperature (Tg) and of the percentage of elongation at break. Moreover, UV treatment accelerated these phenomena.

  5. Generation of ultrashort coherent vacuum ultraviolet pulses using electron storage rings: a new bright light source for experiments.

    PubMed

    De Ninno, G; Allaria, E; Coreno, M; Curbis, F; Danailov, M B; Karantzoulis, E; Locatelli, A; Menteş, T O; Nino, M A; Spezzani, C; Trovò, M

    2008-08-01

    We demonstrate for the first time that seeded harmonic generation on electron storage rings can produce coherent optical pulses in the vacuum ultraviolet spectral range. The experiment is performed at Elettra, where coherent pulses are generated at 132 nm, with a duration of about 100 fs. The light source has a repetition rate of 1 kHz and adjustable polarization; it is very bright, with a peak power several orders of magnitude above that of spontaneous synchrotron radiation. Owing to high stability, the source is used in a test photoemission electron microscopy experiment. We anticipate that seeded harmonic generation on storage rings can lead to unprecedented developments in time-resolved femtosecond spectroscopy and microscopy.

  6. Detection and modeling of leakage current in AlGaN-based deep ultraviolet light-emitting diodes

    SciTech Connect

    Moseley, Michael William; Allerman, Andrew A.; Crawford, Mary H.; Wierer, Jonathan; Smith, Michael L.; Armstrong, Andrew

    2015-03-01

    Current-voltage (IV) characteristics of two AlGaN-based deep ultraviolet (DUV) light-emitting diodes (LEDs) with differing densities of open-core threading dislocations (nanopipes) are analyzed. A three-diode circuit is simulated to emulate the IV characteristics of the DUV-LEDs, but is only able to accurately model the lower leakage current, lower nanopipe density DUV-LED. It was found that current leakage through the nanopipes in these structures is rectifying, despite nanopipes being previously established as inherently n-type. Using defect-sensitive etching, the nanopipes are revealed to terminate within the p-type GaN capping layer of the DUV-LEDs. The circuit model is modified to account for another p-n junction between the n-type nanopipes and the p-type GaN, and an excellent fit to the IV characteristics of the leaky DUV-LED is achieved.

  7. Remarkable improvement in electroluminescence benefited from appropriate electron injection and transporting in ultraviolet organic light-emitting diode

    NASA Astrophysics Data System (ADS)

    You, Fengjiao; Mo, Bingjie; Liu, Liming; Wang, Honghang; Bin Wei; Xu, Jiwen; Zhang, Xiaowen

    2016-08-01

    Suitable thickness of LiF and 4,7-diphenyl-1, 10-phenanthroline with slightly weakened electron injection and transporting is proposed to match the intractable hole injection capacity in ultraviolet organic light-emitting diode (UV OLED). By using this strategy, the device performance is remarkably improved. With 4,4‧-bis(carbazol-9-yl)biphenyl (CBP) and 3-(4-biphenyl)-4-phenyl-5-tert-butylphenyl-1,2,4-triazole (TAZ) as emitters, the UV OLED shows maximum radiance of 5.8 mW/cm2 and external quantum efficiency of 2.1% with emission peak of ~380 nm predominantly from TAZ and noticeable shoulder emission of ~410 nm from CBP. The retarded electron injection and transporting contribute to optimizing hole-electron recombination zone and balance within the emitting layers, which accounts for the improved electroluminescent intensity. The detailed mechanism is further clarified with impedance spectroscopy.

  8. Evaluation of deoxyribonucleic acid (DNA) isolated from human bloodstains exposed to ultraviolet light, heat, humidity, and soil contamination

    SciTech Connect

    McNally, L.; Shaler, R.C.; Baird, M.; Balazs, I.; De Forest, P.; Kobilinsky, L. )

    1989-09-01

    This study was designed to analyze the effects of common environmental insults on the ability to obtain deoxyribonucleic acid (DNA) restriction fragment-length polymorphisms (RFLP) patterns from laboratory prepared specimens. The environmental conditions studied include the exposure of dried bloodstains to varying amounts of relative humidity (0, 33, 67, and 98%), heat (37{degree}C), and ultraviolet light for periods of up to five days. In addition, the effect of drying over a four-day period in whole blood collected with and without ethylenediaminetetraacetate (EDTA) was examined. The results of the study showed that, under the conditions studied, the integrity of DNA is not altered such that false RFLP patterns are obtained. The only effect observed was that the overall RFLP pattern becomes weaker, but individual RFLP fragments are neither created nor destroyed.

  9. A fiber optic, ultraviolet light-emitting diode-based, two wavelength fluorometer for monitoring reactive adsorption

    NASA Astrophysics Data System (ADS)

    Granz, Christopher D.; Schindler, Bryan J.; Peterson, Gregory W.; Whitten, James E.

    2016-03-01

    Construction and use of an ultraviolet light-emitting diode-based fluorometer for measuring photoluminescence (PL) from powder samples with a fiber optic probe is described. Fluorescence at two wavelengths is detected by miniature photomultiplier tubes, each equipped with a different band pass filter, whose outputs are analyzed by a microprocessor. Photoluminescent metal oxides and hydroxides, and other semiconducting nanoparticles, often undergo changes in their emission spectra upon exposure to reactive gases, and the ratio of the PL intensities at two wavelengths is diagnostic of adsorption. Use of this instrument for reactive gas sensing and gas filtration applications is illustrated by measuring changes in the PL ratio for zirconium hydroxide and zinc oxide particles upon exposure to air containing low concentrations of sulfur dioxide.

  10. Transformation of human diploid cells by adenovirus type 4 irradiated with ultraviolet light.

    PubMed

    Hozoc, M; Nastac, E; Suru, M; Stoian, M; Bercovici, S; Cajal, N

    1983-01-01

    Inoculation of ultraviolet (UV)-irradiated adenovirus type 4 (Ad4) led to in vitro transformation of human diploid cells (HDC). Two transformed cell lines could be established: cell line H 1418, from HDC inoculated with the 10(-3) dilution of Ad4 UV-irradiated for 20 min at a distance of 20 cm, co-cultivated with uninfected HDC, and cell line H 1557, from HDC inoculated with the 10(-2) dilution of Ad4 irradiated at the same distance for 12 min. Both transformed cell lines were resistant to superinfection with homologous virus. Virus-specific antigen could be made evident by the indirect immunofluorescence technique in the nuclei of both H 1418 and H 1557 cells.

  11. Riboflavin, overproduced during sporulation of Ashbya gossypii, protects its hyaline spores against ultraviolet light.

    PubMed

    Stahmann, K P; Arst, H N; Althöfer, H; Revuelta, J L; Monschau, N; Schlüpen, C; Gätgens, C; Wiesenburg, A; Schlösser, T

    2001-09-01

    Riboflavin (vitamin B2), essential in tiny amounts as a precursor for oxidoreductase coenzymes, is a yellow pigment. Although it causes cytotoxicity via photoinduced damage of macromolecules, several microorganisms are striking overproducers. A question, unanswered for decades, is whether riboflavin overproducers can benefit from this property. Here, we report an ultraviolet (UV) protective effect of riboflavin. The spores of Ashbya gossypii, a riboflavin-overproducing fungus, are more sensitive to UV than those of Aspergillus nidulans. The addition of riboflavin to suspensions improves the UV resistance of both spore types. Interestingly, we show that regulation of sporulation and riboflavin overproduction in A. gossypii are linked. In batch culture, both were elevated when growth ceased. At constant growth rates, obtained in a chemostat culture, neither was elevated. Supplementation of cultures by cAMP, a known stress signal, negatively affected sporulation as well as riboflavin overproduction, establishing a second, independent argument for the linkage.

  12. Structural and interface properties of an AlN diamond ultraviolet light emitting diode

    SciTech Connect

    Miskys, C.R.; Garrido, J.A.; Hermann, M.; Eickhoff, M.; Nebel, C.E.; Stutzmann, M.; Vogg, G.

    2004-10-25

    Two practically fully relaxed AlN domains were identified by x-ray diffractometry for AlN grown on (100) diamond. The epitaxial orientation relationships (0001)[1010] AlN{sup I} parallel (100)[011] diamond for the predominant AlN domain (type I) and (0001)[1210] AlN{sup II} parallel (100)[011] diamond for the second domain (type II) are obtained. Surface morphology measurements corroborate the good structural quality of the AlN film. In addition, the intrinsic built-in voltage of a n-AlN/p-diamond diode was determined as 1.15 V. By spectrally resolved photocurrent measurements, the ultraviolet electroluminescence emission was confirmed to originate at the heterojunction interface, and is most probably due to a defect center.

  13. A desktop extreme ultraviolet microscope based on a compact laser-plasma light source

    NASA Astrophysics Data System (ADS)

    Wachulak, P. W.; Torrisi, A.; Bartnik, A.; Węgrzyński, Ł.; Fok, T.; Fiedorowicz, H.

    2017-01-01

    A compact, desktop size microscope, based on laser-plasma source and equipped with reflective condenser and diffractive Fresnel zone plate objective, operating in the extreme ultraviolet (EUV) region at the wavelength of 13.8 nm, was developed. The microscope is capable of capturing magnified images of objects with 95-nm full-pitch spatial resolution (48 nm 25-75% KE) and exposure time as low as a few seconds, combining reasonable acquisition conditions with stand-alone desktop footprint. Such EUV microscope can be regarded as a complementary imaging tool to already existing, well-established ones. Details about the microscope, characterization, resolution estimation and real sample images are presented and discussed.

  14. Dim ultraviolet light as a means of deterring activity by the Hawaiian hoary bat Lasiurus cinereus semotus

    USGS Publications Warehouse

    Gorresen, P. Marcos; Cryan, Paul M.; Dalton, David C.; Wolf, Sandy; Johnson, Jessica A.; Todd, Christopher M.; Bonaccorso, Frank J.

    2015-01-01

    Widespread bat fatalities at industrial wind turbines are a conservation issue with the potential to inhibit efficient use of an abundant source of energy. Bat fatalities can be reduced by altering turbine operations, but such curtailment decreases turbine efficiency. If additional ways of reducing bat fatalities at wind turbines were available such tradeoffs might not be needed. Based on the facts that bats perceive distant objects primarily through vision and can see in very dim lighting conditions, and the possibility that bats might interact with turbines after approaching them as they would trees, we propose a novel method of reducing bat activity at wind turbines: illumination of the structure with dim light. As a first step toward assessing this approach, we illuminated trees with dim flickering ultraviolet (UV) light in areas frequented by Hawaiian hoary bats Lasiurus cinereus semotus, an endangered subspecies affected by wind turbines. We used a repeated-measures design to quantify bat activity near trees with acoustic detectors and thermal video cameras in the presence and absence of UV illumination, while concurrently monitoring insect numbers. Results indicate that dim UV reduces bat activity despite an increase in insect numbers. Experimental treatment did not completely inhibit bat activity near trees, nor did all measures of bat activity show statistically significant differences due to high variance in bat activity among sites. However, the observed decreases in bat activity with dim UV illumination justify further testing of this method as a means to reduce bat fatalities at wind turbines.

  15. Single Component Lanthanide Hybrids Based on Metal-Organic Framework for Near-Ultraviolet White Light LED.

    PubMed

    Zhao, Yan-Wu; Zhang, Fu-Qiang; Zhang, Xian-Ming

    2016-09-14

    Near-UV single-phase white-light phosphor (Eu0.045Tb0.955CPOMBA/La0.6Eu0.1Tb0.3CPOMBA) based on metal-organic framework was prepared by in situ doping isostructural lanthanide MOF with Eu(3+) and Tb(3+), and it is found that the energy can effectively transfer from organic ligand to lanthanides, which can overcome weak absorption under direct excitation of lanthanide ions due to the forbidden f-f transitions. The photoluminescence and thermostability of the new MOF phosphor are investigated, and effective white-light emission is achieved under 365 and 380 nm excitations. By employing Eu0.045Tb0.955CPOMBA as phosphor, we fabricated a near-ultraviolet white-light-emitting diode (n-UV WLED) (365 nm) with low CCT (5733 K), high CRI (Ra = 73.4), and CIE chromaticity coordinate (0.3264, 0.3427). This approach may open new perspectives for developing single-phase UV phosphors.

  16. Photovoltaic powered ultraviolet and visible light-emitting diodes for sustainable point-of-use disinfection of drinking waters.

    PubMed

    Lui, Gough Yumu; Roser, David; Corkish, Richard; Ashbolt, Nicholas; Jagals, Paul; Stuetz, Richard

    2014-09-15

    For many decades, populations in rural and remote developing regions will be unable to access centralised piped potable water supplies, and indeed, decentralised options may be more sustainable. Accordingly, improved household point-of-use (POU) disinfection technologies are urgently needed. Compared to alternatives, ultraviolet (UV) light disinfection is very attractive because of its efficacy against all pathogen groups and minimal operational consumables. Though mercury arc lamp technology is very efficient, it requires frequent lamp replacement, involves a toxic heavy metal, and their quartz envelopes and sleeves are expensive, fragile and require regular cleaning. An emerging alternative is semiconductor-based units where UV light emitting diodes (UV-LEDs) are powered by photovoltaics (PV). Our review charts the development of these two technologies, their current status, and challenges to their integration and POU application. It explores the themes of UV-C-LEDs, non-UV-C LED technology (e.g. UV-A, visible light, Advanced Oxidation), PV power supplies, PV/LED integration and POU suitability. While UV-C LED technology should mature in the next 10 years, research is also needed to address other unresolved barriers to in situ application as well as emerging research opportunities especially UV-A, photocatalyst/photosensitiser use and pulsed emission options.

  17. Tunable ultraviolet and blue light generation from Nd:YAB random laser bolstered by second-order nonlinear processes

    PubMed Central

    Moura, André L.; Carreño, Sandra J. M.; Pincheira, Pablo I. R.; Fabris, Zanine V.; Maia, Lauro J. Q.; Gomes, Anderson S. L.; de Araújo, Cid B.

    2016-01-01

    Ultraviolet and blue light were obtained by nonlinear frequency conversion in a random laser (RL) based on Nd0.10Y0.90Al3(BO3)4 nanocrystalline powder. RL operation at 1062 nm, due to the 4F3/2 → 4I11/2 transition of neodymium ions (Nd3+), was achieved by exciting the Nd3+ with a tunable beam from 680 to 920 nm covering the ground state absorption transitions to the 4F9/2, (4F7/2,4S3/2), (4F5/2,2H9/2), and 4F3/2 states. Light from 340 to 460 nm was obtained via the second-harmonic generation of the excitation beam while tunable blue light, from 417 to 486 nm, was generated by self-sum-frequency mixing between the excitation beam and the RL emission. PMID:27250647

  18. Tunable ultraviolet and blue light generation from Nd:YAB random laser bolstered by second-order nonlinear processes

    NASA Astrophysics Data System (ADS)

    Moura, André L.; Carreño, Sandra J. M.; Pincheira, Pablo I. R.; Fabris, Zanine V.; Maia, Lauro J. Q.; Gomes, Anderson S. L.; de Araújo, Cid B.

    2016-06-01

    Ultraviolet and blue light were obtained by nonlinear frequency conversion in a random laser (RL) based on Nd0.10Y0.90Al3(BO3)4 nanocrystalline powder. RL operation at 1062 nm, due to the 4F3/2 → 4I11/2 transition of neodymium ions (Nd3+), was achieved by exciting the Nd3+ with a tunable beam from 680 to 920 nm covering the ground state absorption transitions to the 4F9/2, (4F7/2,4S3/2), (4F5/2,2H9/2), and 4F3/2 states. Light from 340 to 460 nm was obtained via the second-harmonic generation of the excitation beam while tunable blue light, from 417 to 486 nm, was generated by self-sum-frequency mixing between the excitation beam and the RL emission.

  19. Strongly transverse-electric-polarized emission from deep ultraviolet AlGaN quantum well light emitting diodes

    SciTech Connect

    Reich, Christoph Guttmann, Martin; Wernicke, Tim; Mehnke, Frank; Kuhn, Christian; Feneberg, Martin; Goldhahn, Rüdiger; Rass, Jens; Kneissl, Michael; Lapeyrade, Mickael; Einfeldt, Sven; Knauer, Arne; Kueller, Viola; Weyers, Markus

    2015-10-05

    The optical polarization of emission from ultraviolet (UV) light emitting diodes (LEDs) based on (0001)-oriented Al{sub x}Ga{sub 1−x}N multiple quantum wells (MQWs) has been studied by simulations and electroluminescence measurements. With increasing aluminum mole fraction in the quantum well x, the in-plane intensity of transverse-electric (TE) polarized light decreases relative to that of the transverse-magnetic polarized light, attributed to a reordering of the valence bands in Al{sub x}Ga{sub 1−x}N. Using k ⋅ p theoretical model calculations, the AlGaN MQW active region design has been optimized, yielding increased TE polarization and thus higher extraction efficiency for bottom-emitting LEDs in the deep UV spectral range. Using (i) narrow quantum wells, (ii) barriers with high aluminum mole fractions, and (iii) compressive growth on patterned aluminum nitride sapphire templates, strongly TE-polarized emission was observed at wavelengths as short as 239 nm.

  20. New red phosphor for near-ultraviolet light-emitting diodes with high color-purity

    SciTech Connect

    Wang, Zhengliang; He, Pei; Wang, Rui; Zhao, Jishou; Gong, Menglian

    2010-02-15

    New red phosphors, Na{sub 5}Eu(MoO{sub 4}){sub 4} doped with boron oxide were prepared by the solid-state reaction. Their structure and photo-luminescent properties were investigated. With the introduction of boron oxide, the red emission intensity of the phosphors under 395 nm excitation is strengthened, with high color-purity (x = 0.673, y = 0.327). The single red light-emitting diode was obtained by combining InGaN chip with the red phosphor, bright red light can be observed by naked eyes from the red light-emitting diodes under a forward bias of 20 mA.

  1. Measurement of the light absorbing properties of diesel exhaust particles using a three-wavelength photoacoustic spectrometer

    NASA Astrophysics Data System (ADS)

    Guo, Xuesong; Nakayama, Tomoki; Yamada, Hiroyuki; Inomata, Satoshi; Tonokura, Kenichi; Matsumi, Yutaka

    2014-09-01

    Diesel-exhaust particles (DEP) are one of the main anthropogenic sources of black carbon (BC) and organic matter (OM). Understanding the optical properties of DEP, including the enhancement of light absorption by BC due to coating and light absorption by OM, is important for evaluating the climate impact of DEP. In this study, a three-wavelength photoacoustic soot spectrometer (405, 532, and 781 nm) was used to investigate the wavelength-dependent optical properties of DEP emitted from a diesel engine vehicle running on a chassis dynamometer in transient driving mode (JE-05) and at a constant speed (either idling or driving at 70 km/h). Optical properties were measured after passing the diluted exhaust through a heater, set at 20, 47, or 300 °C (transient driving mode) or between 20 and 400 °C (constant driving mode). The OM accounted for, on average, ∼40 and ∼35% of the total mass concentration of DEP during the transient and constant driving modes, respectively. In transient driving mode, enhancements of scattering coefficients at 20 and 47 °C, and of the mass concentration of organics, were observed during the high-speed driving period (∼80 km/h) corresponding to driving on a highway. No difference was observed in the absorption coefficients between heated and unheated particles at 781 nm for either the transient (including the high-speed driving period) or constant driving modes. These results indicate a lack of enhancement due to the lensing effect, possibly because the BC was mainly mixed externally with the OM or because it was located at the edges of particles under these experimental conditions. Contributions to total light absorption at 405 nm by the OM were estimated by comparing the wavelength dependence of the absorption coefficients with and without heating. A significant contribution by light-absorbing OM (20 ± 7%) to total light absorption at 405 nm was observed during the high-speed driving period of the JE-05 mode, while the

  2. Efficacy of on-farm use of ultraviolet light for inactivation of bacteria in milk for calves.

    PubMed

    Gelsinger, S L; Heinrichs, A J; Jones, C M; Van Saun, R J; Wolfgang, D R; Burns, C M; Lysczek, H R

    2014-05-01

    Ultraviolet light is being employed for bacterial inactivation in milk for calves; however, limited evidence is available to support the claim that UV light effectively inactivates bacteria found in milk. Thus, the objective of this observational study was to investigate the efficacy of on-farm UV light treatment in reducing bacteria populations in waste milk used for feeding calves. Samples of nonsaleable milk were collected from 9 Pennsylvania herds, twice daily for 15 d, both before and after UV light treatment (n=60 samples per farm), and analyzed for standard plate count, coliforms, noncoliform, gram-negative bacteria, environmental and contagious streptococci, coagulase-negative staphylococci, Streptococcus agalactiae, Staphylococcus aureus count, and total solids percentage, and log reduction and percentage log reduction were calculated. Data were analyzed using the mixed procedure in SAS. In all bacteria types, samples collected after UV treatment contained significantly fewer bacteria compared with samples collected before UV treatment. Weighted least squares means for log reduction (percentage log reduction) were 1.34 (29%), 1.27 (58%), 1.48 (53%), 1.85 (55%), 1.37 (72%), 1.92 (63%), 1.07 (33%), and 1.67 (82%) for standard plate count, coliforms, noncoliform, gram-negative bacteria, environmental and contagious streptococci, Strep. agalactiae, coagulase-negative staphylococci, and Staph. aureus, respectively. A percentage log reduction greater than 50% was achieved in 6 of 8 bacteria types, and 43 and 94% of samples collected after UV treatment met recommended bacterial standards for milk for feeding calves. Based on these results, UV light treatment may be effective for some, but not all bacteria types found in nonsaleable waste milk. Thus, farmers should take into account the bacteria types that may need to be reduced when considering the purchase of a UV-treatment system.

  3. A new optical method coupling light polarization and Vis-NIR spectroscopy to improve the measured absorbance signal's quality of soil samples.

    NASA Astrophysics Data System (ADS)

    Gobrecht, Alexia; Bendoula, Ryad; Roger, Jean-Michel; Bellon-Maurel, Véronique

    2014-05-01

    Visible - Near-infrared spectroscopy (Vis-NIRS) is now commonly used to measure different physical and chemical parameters of soils, including carbon content. However, prediction model accuracy is insufficient for Vis-NIRS to replace routine laboratory analysis. One of the biggest issues this technique is facing up to is light scattering due to soil particles. It causes departure in the assumed linear relationship between the Absorbance spectrum and the concentration of the chemicals of interest as stated by Beer-Lambert's Law, which underpins the calibration models. Therefore it becomes essential to improve the metrological quality of the measured signal in order to optimize calibration as light/matter interactions are at the basis of the resulting linear modeling. Optics can help to mitigate scattering effect on the signal. We put forward a new optical setup coupling linearly polarized light with a Vis-NIR spectrometer to free the measured spectra from multi-scattering effect. The corrected measured spectrum was then used to compute an Absorbance spectrum of the sample, using Dahm's Equation in the frame of the Representative Layer Theory. This method has been previously tested and validated on liquid (milk+ dye) and powdered (sand + dye) samples showing scattering (and absorbing) properties. The obtained Absorbance was a very good approximation of the Beer-Lambert's law absorbance. Here, we tested the method on a set of 54 soil samples to predict Soil Organic Carbon content. In order to assess the signal quality improvement by this method, we built and compared calibration models using Partial Least Square (PLS) algorithm. The prediction model built from new Absorbance spectrum outperformed the model built with the classical Absorbance traditionally obtained with Vis-NIR diffuse reflectance. This study is a good illustration of the high influence of signal quality on prediction model's performances.

  4. Safety assessment of the post-harvest treatment of button mushrooms (Agaricus bisporus) using ultraviolet light.

    PubMed

    Simon, R R; Borzelleca, J F; DeLuca, H F; Weaver, C M

    2013-06-01

    Wild mushrooms are an excellent source of vitamin D. The presence of vitamin D in mushrooms is attributed to sunlight exposure, which catalyzes the conversion of fungal ergosterol to vitamin D2 via a series of photochemical/thermal reactions. Mushroom growers now incorporate UV light treatments during processing to produce mushrooms with levels of vitamin D that compare to those in wild mushrooms. Presented herein is a comprehensive review of information relevant to the safety of introducing vitamin D mushrooms, produced using UV light technologies, to the food supply. Historical reference to the use of UV light for production of vitamin D is discussed, and studies evaluating the nutritional value and safety of vitamin D mushrooms are reviewed. Traditional safety evaluation practices for food additives are not applicable to whole foods; therefore, the application of substantial equivalence and history-of-safe-use is presented. It was demonstrated that vitamin D in mushrooms, produced using UV light technologies, are equivalent to vitamin D in mushrooms exposed to sunlight, and that UV light has a long-history of safe use for production of vitamin D in food. Vitamin D mushrooms produced using UV light technologies were therefore considered safe and suitable for introduction to the marketplace.

  5. Far-infrared-light shadowgraphy for high extraction efficiency of extreme ultraviolet light from a CO2-laser-generated tin plasma

    NASA Astrophysics Data System (ADS)

    Matsukuma, Hiraku; Hosoda, Tatsuya; Suzuki, Yosuke; Yogo, Akifumi; Yanagida, Tatsuya; Kodama, Takeshi; Nishimura, Hiroaki

    2016-08-01

    The two-color, double-pulse method is an efficient scheme to generate extreme ultraviolet light for fabricating the next generation semiconductor microchips. In this method, a Nd:YAG laser pulse is used to expand a several-tens-of-micrometers-scale tin droplet, and a CO2 laser pulse is subsequently directed at the expanded tin vapor after an appropriate delay time. We propose the use of shadowgraphy with a CO2 laser probe-pulse scheme to optimize the CO2 main-drive laser. The distribution of absorption coefficients is derived from the experiment, and the results are converted to a practical absorption rate for the CO2 main-drive laser.

  6. 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

    Technology Transfer Automated Retrieval System (TEKTRAN)

    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...

  7. Effects of combination of ultraviolet light and hydrogen peroxide on inactivation of Escherichia coli O157:H7, native microbial loads, and quality of button mushrooms

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Mushrooms are prone to microbial spoilage and browning during growing and processing. Ultraviolet light (UV-C) has been used as an alternative technology to chemical sanitizers for food products. Hydrogen peroxide is classified as generally recognized as safe for use in foods as a bleaching and ant...

  8. Large-area surveys for black carbon and other light-absorbing impurities in snow: Arctic, Antarctic, North America, China (Invited)

    NASA Astrophysics Data System (ADS)

    Warren, S. G.; Doherty, S. J.; Hegg, D.; Dang, C.; Zhang, R.; Grenfell, T. C.; Brandt, R. E.; Clarke, A. D.; Zatko, M.

    2013-12-01

    Absorption of radiation by ice is extremely weak at visible and near-UV wavelengths, so small amounts of light-absorbing impurities (LAI) in snow can dominate the absorption of sunlight at these wavelengths, reducing the albedo relative to that of pure snow and leading to earlier snowmelt. Snow samples were collected in Alaska, Canada, Greenland, Svalbard, Norway, Russia, and the Arctic Ocean, on tundra, glaciers, ice caps, sea ice, and frozen lakes, and in boreal forests. Snow was collected mostly in spring, when the entire winter snowpack was accessible for sampling. Snow was also collected at 67 sites in western North America. Expeditions from Lanzhou University obtained black carbon (BC) amounts at 84 sites in northeast and northwest China. BC was measured at 3 locations on the Antarctic Plateau, and at 5 sites on East Antarctic sea ice. The snow is melted and filtered; the filters are analyzed in a spectrophotometer. Median BC mixing ratios in snow range over 4 orders of magnitude from 0.2 ng/g in Antarctica to 1000 ng/g in northeast China. Chemical analyses, input to a receptor model, indicate that the major source of BC in most of the Arctic is biomass burning, but industrial sources dominate in Svalbard and the central Arctic Ocean. Non-BC impurities, principally brown (organic) carbon, are typically responsible for ~40% of the visible and ultraviolet absorption. In northeast China BC is the dominant LAI, but in Inner Mongolia soil dominates. When the snow surface layer melts, much of the BC is left at the top of the snowpack rather than carried away in meltwater, thus causing a positive feedback on snowmelt. This process was quantified through field studies in Greenland, Alaska, and Norway, where we found that only 10-30% of the BC is removed with meltwater. The BC content of the Arctic atmosphere has declined markedly since 1989, according to the continuous measurements of near-surface air in Canada, Alaska, and Svalbard. Correspondingly, our recent BC

  9. The precipitation synthesis of broad-spectrum UV absorber nanoceria

    NASA Astrophysics Data System (ADS)

    Nurhasanah, Iis; Sutanto, Heri; Puspaningrum, Nurul Wahyu

    2013-09-01

    In this paper the possibility of nanoceria as broad-spectrum UV absorber was evaluated. Nanoceria were synthesized by precipitation process from cerium nitrate solution and ammonium hydroxide as precipitant agent. Isopropanol was mixed with water as solvent to prevent hard agglomeration. The structure of resulting nanoceria was characterized by x-ray diffractometer (XRD). The transparency in the visible light and efficiency of protection in UV A region were studied using ultraviolet-visible (UV - Vis) spectrophotometer. The results show that nanoceria possess good tranparency in visible light and high UV light absorption. The critical absorption wavelenght of 368 nm was obtained which is desirable for excellent broad-spectrum protection absorbers. Moreover, analysis of photodegradation nanoceria to methylene blue solution shows poor photocatalytic activity. It indicates that nanoceria suitable for used as UV absorber in personal care products.

  10. The precipitation synthesis of broad-spectrum UV absorber nanoceria

    SciTech Connect

    Nurhasanah, Iis; Sutanto, Heri; Puspaningrum, Nurul Wahyu

    2013-09-09

    In this paper the possibility of nanoceria as broad-spectrum UV absorber was evaluated. Nanoceria were synthesized by precipitation process from cerium nitrate solution and ammonium hydroxide as precipitant agent. Isopropanol was mixed with water as solvent to prevent hard agglomeration. The structure of resulting nanoceria was characterized by x-ray diffractometer (XRD). The transparency in the visible light and efficiency of protection in UV A region were studied using ultraviolet-visible (UV - Vis) spectrophotometer. The results show that nanoceria possess good tranparency in visible light and high UV light absorption. The critical absorption wavelenght of 368 nm was obtained which is desirable for excellent broad-spectrum protection absorbers. Moreover, analysis of photodegradation nanoceria to methylene blue solution shows poor photocatalytic activity. It indicates that nanoceria suitable for used as UV absorber in personal care products.

  11. Visible light neutralizes the effect produced by ultraviolet radiation in proteins.

    PubMed

    Espinoza, J Horacio; Mercado-Uribe, Hilda

    2017-02-01

    The damage produced by UV-C radiation (100-280nm) in organisms and cells is a well known fact. The main reactions of proteins to UV-C radiation consist in the alteration of their secondary structures, exposure of hydrophobic residues, unfolding and aggregation. Furthermore, it has been found that electromagnetic radiation of lower energy (visible light, where wavelengths are between 400 and 750nm) also induces different disturbances in biomolecules. For instance, it has been observed that blue visible light from emitting diodes (LEDs) produces severe damage in murine cone photoreceptor-derived cells, and it can be even more harmful for some organisms than UV radiation. Recently, it has been found that the exposure of proteins to green and red light produces conformational changes, considerably increasing their cohesion enthalpies. This is presumably due to the strengthening of the hydrogen bonds and the formation of new ones. Therefore, it seems that visible light acts contrary to what it is observed for UV-C: instead of unfolding the proteins it folds them further, halting the damage produced by UV-C. This can be understood if we consider the modification of the folding energy-landscape; visible light induces the descent of the proteins into deeper states impeding the unfolding produced by UV-C.

  12. Computational On-Chip Imaging of Nanoparticles and Biomolecules using Ultraviolet Light

    NASA Astrophysics Data System (ADS)

    Daloglu, Mustafa Ugur; Ray, Aniruddha; Gorocs, Zoltan; Xiong, Matthew; Malik, Ravinder; Bitan, Gal; McLeod, Euan; Ozcan, Aydogan

    2017-03-01

    Significant progress in characterization of nanoparticles and biomolecules was enabled by the development of advanced imaging equipment with extreme spatial-resolution and sensitivity. To perform some of these analyses outside of well-resourced laboratories, it is necessary to create robust and cost-effective alternatives to existing high-end laboratory-bound imaging and sensing equipment. Towards this aim, we have designed a holographic on-chip microscope operating at an ultraviolet illumination wavelength (UV) of 266 nm. The increased forward scattering from nanoscale objects at this short wavelength has enabled us to detect individual sub-30 nm nanoparticles over a large field-of-view of >16 mm2 using an on-chip imaging platform, where the sample is placed at ≤0.5 mm away from the active area of an opto-electronic sensor-array, without any lenses in between. The strong absorption of this UV wavelength by biomolecules including nucleic acids and proteins has further enabled high-contrast imaging of nanoscopic aggregates of biomolecules, e.g., of enzyme Cu/Zn-superoxide dismutase, abnormal aggregation of which is linked to amyotrophic lateral sclerosis (ALS) - a fatal neurodegenerative disease. This UV-based wide-field computational imaging platform could be valuable for numerous applications in biomedical sciences and environmental monitoring, including disease diagnostics, viral load measurements as well as air- and water-quality assessment.

  13. Computational On-Chip Imaging of Nanoparticles and Biomolecules using Ultraviolet Light

    PubMed Central

    Daloglu, Mustafa Ugur; Ray, Aniruddha; Gorocs, Zoltan; Xiong, Matthew; Malik, Ravinder; Bitan, Gal; McLeod, Euan; Ozcan, Aydogan

    2017-01-01

    Significant progress in characterization of nanoparticles and biomolecules was enabled by the development of advanced imaging equipment with extreme spatial-resolution and sensitivity. To perform some of these analyses outside of well-resourced laboratories, it is necessary to create robust and cost-effective alternatives to existing high-end laboratory-bound imaging and sensing equipment. Towards this aim, we have designed a holographic on-chip microscope operating at an ultraviolet illumination wavelength (UV) of 266 nm. The increased forward scattering from nanoscale objects at this short wavelength has enabled us to detect individual sub-30 nm nanoparticles over a large field-of-view of >16 mm2 using an on-chip imaging platform, where the sample is placed at ≤0.5 mm away from the active area of an opto-electronic sensor-array, without any lenses in between. The strong absorption of this UV wavelength by biomolecules including nucleic acids and proteins has further enabled high-contrast imaging of nanoscopic aggregates of biomolecules, e.g., of enzyme Cu/Zn-superoxide dismutase, abnormal aggregation of which is linked to amyotrophic lateral sclerosis (ALS) - a fatal neurodegenerative disease. This UV-based wide-field computational imaging platform could be valuable for numerous applications in biomedical sciences and environmental monitoring, including disease diagnostics, viral load measurements as well as air- and water-quality assessment. PMID:28276489

  14. Computational On-Chip Imaging of Nanoparticles and Biomolecules using Ultraviolet Light.

    PubMed

    Daloglu, Mustafa Ugur; Ray, Aniruddha; Gorocs, Zoltan; Xiong, Matthew; Malik, Ravinder; Bitan, Gal; McLeod, Euan; Ozcan, Aydogan

    2017-03-09

    Significant progress in characterization of nanoparticles and biomolecules was enabled by the development of advanced imaging equipment with extreme spatial-resolution and sensitivity. To perform some of these analyses outside of well-resourced laboratories, it is necessary to create robust and cost-effective alternatives to existing high-end laboratory-bound imaging and sensing equipment. Towards this aim, we have designed a holographic on-chip microscope operating at an ultraviolet illumination wavelength (UV) of 266 nm. The increased forward scattering from nanoscale objects at this short wavelength has enabled us to detect individual sub-30 nm nanoparticles over a large field-of-view of >16 mm(2) using an on-chip imaging platform, where the sample is placed at ≤0.5 mm away from the active area of an opto-electronic sensor-array, without any lenses in between. The strong absorption of this UV wavelength by biomolecules including nucleic acids and proteins has further enabled high-contrast imaging of nanoscopic aggregates of biomolecules, e.g., of enzyme Cu/Zn-superoxide dismutase, abnormal aggregation of which is linked to amyotrophic lateral sclerosis (ALS) - a fatal neurodegenerative disease. This UV-based wide-field computational imaging platform could be valuable for numerous applications in biomedical sciences and environmental monitoring, including disease diagnostics, viral load measurements as well as air- and water-quality assessment.

  15. Induction of chromosome damage by ultraviolet light and caffeine: correlation of cytogenetic evaluation and flow karyotype

    SciTech Connect

    Cremer, C.; Cremer, T.; Gray, J.W.

    1982-03-01

    Asynchronously growing cells of a M3-1 Chinese hamster line were ultraviolet (UV) irradiated (lambda . 254 nm) with UV fluences up to 7.5 J/m(2). After irradiation cells were incubated with or without 2 mM caffeine for 20 hr, then mitotic cells were selected by mechanical shaking. Their chromosomes were isolated, stained with Hoechst 33258 and chromomycin A3, and measured flow cytometrically. While the fluorescence distributions of chromosomes (flow karyo-types) from cells treated with UV alone or with caffeine alone were very similar to those of untreated controls, the flow karyo-types of UV + caffeine-treated cells showed a debris continuum that increased with increasing UV fluence suggesting an increased number of chromosome fragments. Visual evaluation of metaphase plates revealed that the percentage of cells with chromosome damage also increased steadily with increasing UV fluence. A high degree of correlation was observed between the relative magnitude of the debris level from flow karyotypes and the percentage of cells with chromosome damage and with generalized chromosomes shattering, respectively, as determined from metaphase spreads.

  16. Induction of chromosome damage by ultraviolet light and caffeine: correlation of cytogenetic evaluation and flow karyotype

    SciTech Connect

    Cremer, C.; Cremer, T.; Gray, J.W.

    1982-01-01

    Asynchronously growing cells of a M3-1 Chinese hamster line were ultraviolet (uv) irradiated (lambda = 254 nm) with uv fluences up to 7.5 J/m/sup 2/. After irradiation, cells were incubated with or without 2 mM caffeine for 20 hr, then mitotic cells were selected by mechanical shaking. Their chromosomes were isolated, stained with Hoechst 33258 and chromomycin A3, and measured flow cytometrically. While the fluorescence distributions of chromosomes (flow karyotypes) from cells treated with uv alone or with caffeine alone were very similar to those of untreated controls, the flow karyotypes of uv + caffeine-treated cells showed a debris continuum that increased with increasing uv fluence suggesting an increased number of chromosome fragments. Visual evaluation of metaphase plates revealed that the percentage of cells with chromosome damage also increased steadily with increasing uv fluence. A high degree of correlation was observed between the relative magnitude of the debris level from flow karyotypes and the percentage of cells with chromosome damage and with generalized chromosome shattering, respectively, as determined from metaphase spreads.

  17. Long-wave ultraviolet light induces phospholipase activation in cultured human epidermal keratinocytes

    SciTech Connect

    Hanson, D.; DeLeo, V. )

    1990-08-01

    Long wave ultraviolet radiation (UVA) has been shown to play an important role in the overall response of skin to solar radiation, including sunburn, tanning, premature aging, and non-melanoma skin cancer. UVA induction of inflammation in human skin is thought to be mediated by membrane lipid derived products. In order to investigate the mechanism of this response we examined the effect of UVA on phospholipid metabolism of human epidermal keratinocytes in culture. Keratinocytes were grown in serum free low calcium medium. The cells were prelabeled with (3H) arachidonic acid or (3H) choline and irradiated with UVA (Honle 2002-Hg vapor lamp). Identification and quantitation of specific membrane phospholipid-derived components was achieved using high-performance liquid chromatography, paper chromatography, and radioimmunoassay. UVA resulted in a linear dose dependent release of (3H) arachidonic acid into medium between 1 and 20 joule/cm2. This response was inhibited in an oxygen-reduced environment. The radiolabel released was predominantly free arachidonate and cyclooxygenase metabolites. Cyclooxygenase metabolites prostaglandin E2 and prostacyclin derivative, 6-keto-prostaglandin F1a, were stimulated following UVA irradiation, but the lipoxygenase metabolite, leukotriene B was not detected. Maximal release was measured immediately after irradiation and changed little over 24 h post-irradiation. UVA stimulated an increase of (3H) choline metabolites glycerophosphorylcholine and phosphorylcholine in media extracts suggesting UVA activation of phospholipase C and phospholipase A2 or diacylglyceride lipase.

  18. Ultraviolet-light-driven doping modulation in chemical vapor deposition grown graphene.

    PubMed

    Iqbal, M Z; Iqbal, M W; Khan, M F; Eom, Jonghwa

    2015-08-28

    The tuning of charge carrier density of graphene is an essential factor to achieve the integration of high-efficiency electronic and optoelectronic devices. We demonstrate the reversible doping in graphene using deep ultraviolet (UV) irradiation and treatment with O2 and N2 gases. The Dirac point shift towards a positive gate voltage of chemical vapor deposition grown graphene field-effect transistors confirms the p-type doping, which is observed under UV irradiation and treatment with O2 gas, while it restores its pristine state after treatment with N2 gas under UV irradiation. The emergence of an additional peak in the X-ray photoelectron spectra during UV irradiation and treatment with O2 gas represents the oxidation of graphene, and the elimination of this peak during UV irradiation and treatment with N2 gas reveals the restoration of graphene in its pristine state. The shift in the G and 2D bands in Raman spectra towards higher and then lower wavenumber also suggests p-type doping and then reversible doping in graphene. The controlled doping and its reversibility in large area grown graphene offer a new vision for electronic applications.

  19. Photo-degradation of clofibric acid by ultraviolet light irradiation at 185 nm.

    PubMed

    Li, Wenzhen; Lu, Shuguang; Chen, Nuo; Gu, Xiaogang; Qiu, Zhaofu; Fan, Ji; Lin, Kuangfei

    2009-01-01

    As a metabolite of lipid regulators, clofibric acid (CA) was investigated in this study for its ultraviolet (UV) degradation at monochromatic wavelength of 185 nm using Milli-Q water and sewage treatment plant (STP) effluent. The effects of CA initial concentration, solution pH, humic acid (HA), nitrate and bicarbonate anions on CA degradation performances were evaluated. All CA degradation patterns well fitted the pseudo-first-order kinetic model. The results showed that OH generated from water photolysis by UV185 irradiation was involved, resulting in indirect CA photolysis but contributed less to the whole CA removal when compared to the main direct photolysis process. Acid condition favored slightly to CA degradation and other constituents in solution, such as HA (5.0-100.0 mg L(-1)), nitrate and bicarbonate anions (1.0x10(-3) mol L(-1) and 0.1 mol L(-1)), had negative effects on CA degradation. When using real STP effluent CA degradation could reach 97.4% (without filtration) and 99.3% (with filtration) after 1 hr irradiation, showing its potential mean in pharmaceuticals removal in UV disinfection unit. Mineralization tests showed that rapid chloride ion release happened, resulting in no chlorinated intermediates accumulation, and those non-chlorinated intermediate products could further be nearly completely degraded to CO2 and H2O after 6 hrs.

  20. Enhancing osteoblast-affinity of titanium scaffolds for bone engineering by use of ultraviolet light treatment.

    PubMed

    Ishijima, Manabu; Soltanzadeh, Pooya; Hirota, Makoto; Tsukimura, Naoki; Shigami, Tomohiko; Ogawa, Takahiro

    2015-01-01

    Ultraviolet (UV) treatment immediately prior to use is attracting attention as an effective surface conditioning method for titanium to improve osteoblast-affinity. The affinity of titanium to osteoblasts in two-dimensional plate culture has been well studied, but that in three-dimensional cultures remains unclear. Here, we examined the effect of UV treatment on titanium scaffolds, comprising micro-thin titanium fibers, used in bone engineering. Titanium scaffolds, with and without UV treatment, were seeded with rat bone marrow derived osteoblasts, and the number of cells attached to scaffolds and osteoblastic phenotype in the cultures were examined. UV treatment improved the wettability of scaffolds and significantly reduced the percentage of surface carbon. Along with these physicochemical changes in the scaffolds, cell attachment increased by a factor of 1.3 as compared to that of the untreated control. In addition, alkaline phosphatase activity and calcium deposition significantly increased by a factor of 2.3 and 2.0, respectively. Robust formation of mineralized structures consisting of clear peaks of calcium and phosphorus was observed in the UV-treated scaffolds. The observed increase in osteoblast affinity and capability of mineralized matrix formation indicates the potential use of UV-treated titanium scaffolds for bone engineering.