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Sample records for absorbs blue light

  1. Dose determination with nitro blue tetrazolium containing radiochromic dye films by measuring absorbed and reflected light

    DEFF Research Database (Denmark)

    Kovács, A.; Baranyai, M.; Wojnárovits, L.

    2000-01-01

    Tetrazolium salts as heterocyclic organic compounds are known to form highly coloured, water insoluble formazans by reduction, which can be utilized in radiation processing dosimetry. Radiochromic films containing nitro blue tetrazolium dissolved in a polymer matrix were found suitable for dose...

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

    Science.gov (United States)

    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 light; and (5) as a control not attenuating these wavebands. Attenuation of blue light significantly reduced the flavonoid content in leaf adaxial epidermis and reduced the whole-leaf concentrations of quercetin derivatives relative to kaempferol derivatives. In contrast, UV-B responses were not significant. These results show that pea plants regulate epidermal UV-A absorbance and accumulation of individual flavonoids by perceiving complex radiation signals that extend into the visible region of the solar spectrum. Furthermore, solar blue light instead of solar UV-B radiation can be the main regulator of phenolic compound accumulation in plants that germinate and develop outdoors. © 2014 John Wiley & Sons Ltd.

  3. Effect of elevated manganese on the ultraviolet- and blue light-absorbing compounds of cucumber cotyledons and leaf tissues

    International Nuclear Information System (INIS)

    Caldwell, C.R.

    1998-01-01

    The effect of manganese [Mn(II)] on the pigments of cucumber (Cucumis sativus L., cv Poinsett 76) leaf and cotyledon tissues was investigated. Tissue disks (7 mm) were exposed to increasing Mn(II) concentrations from 100 micromolar to 2.5 mM. Acetone (carotenoid-rich fraction) and acidified methanol (flavonoid-rich fraction) extracts were analyzed by high performance liquid chromatography. Although none of the Mn(II)-treated tissues showed visible damage, Mn(II) at concentrations of 250 micromolar and above significantly reduced (60%) the beta-carotene levels of light-incubated leaf tissues. A major Mn(II)-induced, UV-absorbing compound was observed in methanol extracts of cotyledonary tissues exposed to Mn(II) in the dark. In leaf tissues, Mn(II) reduced the levels of certain UV-absorbing compounds under both light conditions. These results demonstrate that excess leaf Mn(II) can rapidly impair isoprenoid metabolism, altering tissue carotenoid composition. Furthermore, Mn(II) may also modify phenylpropanoid metabolism, changing the tissue flavonoid composition. Both situations could sensitize plant tissues to oxidative stresses, particularly enhanced solar UV-B radiation, and may reduce the nutritional quality of leafy vegetables

  4. [Blue light and eye health].

    Science.gov (United States)

    Zou, Leilei; Dai, Jinhui

    2015-01-01

    Blue light, with the wavelength between 400 nm and 500 nm, has caused public concern because of the injury to the retinal cells. Meanwhile, it is important in circadian rhythm regulation, scotopic vision and ocular growth. Is the blue light safe? Should it be eliminated from the daily life? Here we review the effect and safety of the blue light.

  5. Visible light broadband perfect absorbers

    Energy Technology Data Exchange (ETDEWEB)

    Jia, X. L.; Meng, Q. X.; Yuan, C. X.; Zhou, Z. X.; Wang, X. O., E-mail: wxo@hit.edu.cn [School of Science, Harbin Institute of Technology, Harbin 150001 (China)

    2016-03-15

    The visible light broadband perfect absorbers based on the silver (Ag) nano elliptical disks and holes array are studied using finite difference time domain simulations. The semiconducting indium silicon dioxide thin film is introduced as the space layer in this sandwiched structure. Utilizing the asymmetrical geometry of the structures, polarization sensitivity for transverse electric wave (TE)/transverse magnetic wave (TM) and left circular polarization wave (LCP)/right circular polarization wave (RCP) of the broadband absorption are gained. The absorbers with Ag nano disks and holes array show several peaks absorbance of 100% by numerical simulation. These simple and flexible perfect absorbers are particularly desirable for various potential applications including the solar energy absorber.

  6. Blue light regulated shade avoidance.

    Science.gov (United States)

    Keuskamp, Diederik H; Keller, Mercedes M; Ballaré, Carlos L; Pierik, Ronald

    2012-04-01

    Most plants grow in dense vegetation with the risk of being out-competed by neighboring plants. These neighbors can be detected not only through the depletion in light quantity that they cause, but also through the change in light quality, which plants perceive using specific photoreceptors. Both the reduction of the red:far-red ratio and the depletion of blue light are signals that induce a set of phenotypic traits, such as shoot elongation and leaf hyponasty, which increase the likelihood of light capture in dense plant stands. This set of phenotypic responses are part of the so called shade avoidance syndrome (SAS). This addendum discusses recent findings on the regulation of the SAS of Arabidopsis thaliana upon blue light depletion. Keller et al. and Keuskamp et al. show that the low blue light attenuation induced shade avoidance response of seedling and rosette-stage A. thaliana plants differ in their hormonal regulation. These studies also show there is a regulatory overlap with the R:FR-regulated SAS.

  7. Morphological responses of wheat to blue light

    Science.gov (United States)

    Barnes, C.; Bugbee, B.

    1992-01-01

    Blue light significantly increased tillering in wheat (Triticum aestivum L.) plants grown at the same photosynthetic photon flux (PPF). Plants were grown under two levels of blue light (400-500 nm) in a controlled environment with continuous irradiation. Plants received either 50 micromoles m-2 s-1 of blue light or 2 micromoles m-2 s-1 blue light from filtered metal halide lamps at a total irradiance of 200 micromoles m-2 s-1 PPF (400-700 nm). Plants tillered an average of 25% more under the higher level of blue light. Blue light also caused a small, but consistent, increase in main culm development, measured as Haun stage. Leaf length was reduced by higher levels of blue light, while plant dry-mass was not significantly affected by blue light. Applying the principle of equivalent light action, the results suggest that tillering and leaf elongation are mediated by the blue-UV light receptor(s) because phytochrome photoequilibrium for each treatment were nearly identical.

  8. Blue enhanced light sources: opportunities and risks

    Science.gov (United States)

    Lang, Dieter

    2012-03-01

    Natural daylight is characterized by high proportions of blue light. By proof of a third type of photoreceptor in the human eye which is only sensitive in this spectral region and by subsequent studies it has become obvious that these blue proportions are essential for human health and well being. In various studies beneficial effects of indoor lighting with higher blue spectral proportions have been proven. On the other hand with increasing use of light sources having enhanced blue light for indoor illumination questions are arising about potential health risks attributed to blue light. Especially LED are showing distinct emission characteristics in the blue. Recently the French agency for food, environmental and occupational health & safety ANSES have raised the question on health issues related to LED light sources and have claimed to avoid use of LED for lighting in schools. In this paper parameters which are relevant for potential health risks will be shown and their contribution to risk factors will quantitatively be discussed. It will be shown how to differentiate between photometric parameters for assessment of beneficial as well as hazardous effects. Guidelines will be discussed how blue enhanced light sources can be used in applications to optimally support human health and well being and simultaneously avoid any risks attributed to blue light by a proper design of lighting parameters. In the conclusion it will be shown that no inherent health risks are related to LED lighting with a proper lighting design.

  9. Blue light-mediated inactivation of Enterococcus faecalis in vitro.

    Science.gov (United States)

    Pileggi, Giorgio; Wataha, John C; Girard, Myriam; Grad, Iwona; Schrenzel, Jacques; Lange, Norbert; Bouillaguet, Serge

    2013-05-01

    In dentistry, residual infection remains a major cause of failure after endodontic treatment; many of these infections involve Enterococcus faecalis. In the current study, we explored the possibility that blue light activated photosensitizers could be used, in principle, to inactivate this microbe as an adjunct disinfection strategy for endodontic therapy. Three blue light absorbing photosensitizers, eosin-Y, rose bengal, and curcumin, were tested on E. faecalis grown in planktonic suspensions or biofilms. Photosensitizers were incubated for 30 min with bacteria then exposed to blue light (450-500 nm) for 240 s. Sodium hypochlorite (3%) was used as a control. After 48 h, the viability of E. faecalis was estimated by measuring colony-forming units post-exposure vs. untreated controls (CFU/mL). Blue light irradiation alone did not alter E. faecalis viability. For planktonic cultures, blue light activated eosin-Y (5 μM), rose bengal (1 μM), or curcumin (5 μM) significantly (pcurcumin of 100, 10, and 10 μM respectively, completely suppressed E. faecalis viability (p<0.05). Although the current results are limited to an in vitro model, they support further exploration of blue light activated antimicrobials as an adjunct therapy in endodontic treatment. Copyright © 2012 Elsevier B.V. All rights reserved.

  10. [The dangers of blue light: True story!].

    Science.gov (United States)

    Renard, G; Leid, J

    2016-05-01

    The dangers of the blue light are the object of numerous publications, for both the scientific community and the general public. The new prolific development of light sources emitting potentially toxic blue light (415-455nm) ranges from LED (Light Emitting Diodes) lamps for interior lighting to television screens, computers, digital tablets and smartphones using OLED (Organic Light Emitting Diode) or AMOLED (Active-Matrix Organic Light Emitting Diode) technology. First we will review some technical terms and the main characteristics of light perceived by the human eye. Then we will discuss scientific proof of the toxicity of blue light to the eye, which may cause cataract or macular degeneration. Analysis of the light spectra of several light sources, from natural light to LED lamps, will allow us to specify even better the dangers related to each light source. LED lamps, whether used as components for interior lighting or screens, are of concern if they are used for extended viewing times and at short distance. While we can protect ourselves from natural blue light by wearing colored glasses which filter out, on both front and back surfaces, the toxic wavelengths, it is more difficult to protect oneself from LED lamps in internal lighting, the use of which should be restricted to "white warmth" lamps (2700K). As far as OLED or AMOLED screens are concerned, the only effective protection consists of using them occasionally and only for a short period of time. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

  11. Blue light emitting thiogallate phosphor

    Science.gov (United States)

    Dye, Robert C.; Smith, David C.; King, Christopher N.; Tuenge, Richard T.

    1998-01-01

    A crystalline blue emitting thiogallate phosphor of the formula RGa.sub.2 S.sub.4 :Ce.sub.x where R is selected from the group consisting of calcium, strontium, barium and zinc, and x is from about 1 to 10 atomic percent, the phosphor characterized as having a crystalline microstructure on the size order of from about 100 .ANG. to about 10,000 .ANG. is provided together with a process of preparing a crystalline blue emitting thiogallate phosphor by depositing on a substrate by CVD and resultant thin film electroluminescent devices including a layer of such deposited phosphor on an ordinary glass substrate.

  12. Blue light inhibits proliferation of melanoma cells

    Science.gov (United States)

    Becker, Anja; Distler, Elisabeth; Klapczynski, Anna; Arpino, Fabiola; Kuch, Natalia; Simon-Keller, Katja; Sticht, Carsten; van Abeelen, Frank A.; Gretz, Norbert; Oversluizen, Gerrit

    2016-03-01

    Photobiomodulation with blue light is used for several treatment paradigms such as neonatal jaundice, psoriasis and back pain. However, little is known about possible side effects concerning melanoma cells in the skin. The aim of this study was to assess the safety of blue LED irradiation with respect to proliferation of melanoma cells. For that purpose we used the human malignant melanoma cell line SK-MEL28. Cell proliferation was decreased in blue light irradiated cells where the effect size depended on light irradiation dosage. Furthermore, with a repeated irradiation of the melanoma cells on two consecutive days the effect could be intensified. Fluorescence-activated cell sorting with Annexin V and Propidium iodide labeling did not show a higher number of dead cells after blue light irradiation compared to non-irradiated cells. Gene expression analysis revealed down-regulated genes in pathways connected to anti-inflammatory response, like B cell signaling and phagosome. Most prominent pathways with up-regulation of genes were cytochrome P450, steroid hormone biosynthesis. Furthermore, even though cells showed a decrease in proliferation, genes connected to the cell cycle were up-regulated after 24h. This result is concordant with XTT test 48h after irradiation, where irradiated cells showed the same proliferation as the no light negative control. In summary, proliferation of melanoma cells can be decreased using blue light irradiation. Nevertheless, the gene expression analysis has to be further evaluated and more studies, such as in-vivo experiments, are warranted to further assess the safety of blue light treatment.

  13. Approaches to blue light emitting polymers

    International Nuclear Information System (INIS)

    Taylor, R.M.

    2000-01-01

    Blue-light emitting polymers are important for full colour displays. Blue- light emitting polymers, such as poly(fluorene)s have been reported, but tend to be soluble in the conjugated form. The aim of the project was to produce insoluble polymers, prepared via processible soluble precursor polymers, so that multilayer devices could be easily fabricated. Multilayer devices are often required for more efficient light emission. The target materials were derivatives of poly(p-phenylenevinylene) (PPV), a green-yellow emitting polymer. To blue shift the emission of PPV, bulky substituents, namely chloro, phenyl and alkyl, were attached to the vinylic linkage. These bulky substituents were incorporated to introduce steric interactions between the side group and the backbone phenyl protons, to shorten the effective conjugation length and increase the HOMO-LUMO energy gap. Chloro substituents quenched the fluorescence. Phenyl substituents resulted in highly conjugated precursor polymers with low molecular weights, showing blue- green to green emission in the conjugated form. Alkyl substituted PPV derivatives, prepared via chloro or xanthate precursors, were blue-light emitting conjugated polymers, which were electroluminescent in ITO/polymer/AI devices. The PL quantum yields were found to be up to 38%. The incorporation of electron withdrawing groups into the polymers was attempted, to lower the barrier to electron injection. Chloro groups quenched fluorescence and methylsulfone substituents resulted in insoluble polymers, probably due to cross-linking. However a copolymer containing methylsulfone electron withdrawing groups could be prepared. Phenylsulfone substituents were found to give fluorescent polymers which were soluble in the precursor form. (author)

  14. UV-A/Blue-Light responses in algae

    Science.gov (United States)

    Senger, Horst; Hermsmeier, Dieter

    1994-01-01

    All life on earth depends on light. A variety of photoreceptors capture the light for a wide range of reactions. Photosynthetic organisms absorb the light necessary for energy transformation and charge separation facilitating photosynthesis. In addition to the bulk pigments there is a great diversity of photoreceptors present in minute concentrations that control development, metabolism and orientation of plants and microorganisms. Based on its spectral absorbance, the well-studied phytochrome system acts in the RL (red light) region as well as in the UV-A/BL (blue light) region where the above mentioned reactions are mediated by a variety of photoreceptors whose natures are largely unknown. Phyllogenetically the UV-A/BL photoreceptors seem to be more ancient pigments that eventually were replaced by the phytochrome system. However, there are many reports that suggest a coaction between the UV-A/BL receptors and the phytochrome system. In several cases the UV-A/BL activation is the prerequisite for the phytochrome reaction. Historically it was the German botanist Julius Sachs who first discovered in 1864 that phototropism in plants was due to BL reactions. It took over 70 years until Bunning (1937) and Galston and Baker (1949) rediscovered the BL response. Since then, an ever-increasing attention has been paid to this effect. In this contribution, the general aspect of UV-A/BL responses and especially the responsiveness of algae will be covered.

  15. Blue light does not inhibit nodulation in Sesbania rostrata.

    Science.gov (United States)

    Shimomura, Aya; Arima, Susumu; Hayashi, Makoto; Maymon, Maskit; Hirsch, Ann M; Suzuki, Akihiro

    2017-01-02

    Earlier, we reported that root nodulation was inhibited by blue light irradiation of Lotus japonicus. Because some legumes do not establish nodules exclusively on underground roots, we investigated whether nodule formation in Sesbania rostrata, which forms both root and "stem" nodules following inoculation with Azorhizobium caulinodans, is inhibited by blue light as are L. japonicus nodules. We found that neither S. rostrata nodulation nor nitrogen fixation was inhibited by blue light exposure. Moreover, although A. caulinodans proliferation was not affected by blue light irradiation, bacterial survival was decreased. Therefore, blue light appears to impose different responses depending on the legume-rhizobial symbiosis.

  16. Blue Light Protects Against Temporal Frequency Sensitive Refractive Changes.

    Science.gov (United States)

    Rucker, Frances; Britton, Stephanie; Spatcher, Molly; Hanowsky, Stephan

    2015-09-01

    Time spent outdoors is protective against myopia. The outdoors allows exposure to short-wavelength (blue light) rich sunlight, while indoor illuminants can be deficient at short-wavelengths. In the current experiment, we investigate the role of blue light, and temporal sensitivity, in the emmetropization response. Five-day-old chicks were exposed to sinusoidal luminance modulation of white light (with blue; N = 82) or yellow light (without blue; N = 83) at 80% contrast, at one of six temporal frequencies: 0, 0.2, 1, 2, 5, 10 Hz daily for 3 days. Mean illumination was 680 lux. Changes in ocular components and corneal curvature were measured. Refraction, eye length, and choroidal changes were dependent on the presence of blue light (P blue light, refraction did not change across frequencies (mean change -0.24 [diopters] D), while in the absence of blue light, we observed a hyperopic shift (>1 D) at high frequencies, and a myopic shift (>-0.6 D) at low frequencies. With blue light there was little difference in eye growth across frequencies (77 μm), while in the absence of blue light, eyes grew more at low temporal frequencies and less at high temporal frequencies (10 vs. 0.2 Hz: 145 μm; P blue light. Illuminants rich in blue light can protect against myopic eye growth when the eye is exposed to slow changes in luminance contrast as might occur with near work.

  17. Blue Light Protects Against Temporal Frequency Sensitive Refractive Changes

    Science.gov (United States)

    Rucker, Frances; Britton, Stephanie; Spatcher, Molly; Hanowsky, Stephan

    2015-01-01

    Purpose Time spent outdoors is protective against myopia. The outdoors allows exposure to short-wavelength (blue light) rich sunlight, while indoor illuminants can be deficient at short-wavelengths. In the current experiment, we investigate the role of blue light, and temporal sensitivity, in the emmetropization response. Methods Five-day-old chicks were exposed to sinusoidal luminance modulation of white light (with blue; N = 82) or yellow light (without blue; N = 83) at 80% contrast, at one of six temporal frequencies: 0, 0.2, 1, 2, 5, 10 Hz daily for 3 days. Mean illumination was 680 lux. Changes in ocular components and corneal curvature were measured. Results Refraction, eye length, and choroidal changes were dependent on the presence of blue light (P blue light, refraction did not change across frequencies (mean change −0.24 [diopters] D), while in the absence of blue light, we observed a hyperopic shift (>1 D) at high frequencies, and a myopic shift (>−0.6 D) at low frequencies. With blue light there was little difference in eye growth across frequencies (77 μm), while in the absence of blue light, eyes grew more at low temporal frequencies and less at high temporal frequencies (10 vs. 0.2 Hz: 145 μm; P blue light. Conclusions Illuminants rich in blue light can protect against myopic eye growth when the eye is exposed to slow changes in luminance contrast as might occur with near work. PMID:26393671

  18. Blue light screening reduce blue light photosynthesis effeciency of cyanolichens compared with chlorolichens

    OpenAIRE

    Xie, Li

    2012-01-01

    Cyanolichens have phycobiliproteins that mainly absorb light in the green part of the spectrum. Thereby, phycobiliproteins enhance the utilization of light transmitted through a canopy. The combination of phycobiliproteins and chl a may thus improve photosynthesis in shaded forest sites. We compared the chlorolichens Lobaria pulmonaria and Peltigera leucophlebia with the cyanolichens Lobaria hallii and Peltigera praetextata by measuring light response curves for photosynthetic CO2 up...

  19. An anion channel in Arabidopsis hypocotyls activated by blue light

    Science.gov (United States)

    Cho, M. H.; Spalding, E. P.; Evans, M. L. (Principal Investigator)

    1996-01-01

    A rapid, transient depolarization of the plasma membrane in seedling stems is one of the earliest effects of blue light detected in plants. It appears to play a role in transducing blue light into inhibition of hypocotyl (stem) elongation, and perhaps other responses. The possibility that activation of a Cl- conductance is part of the depolarization mechanism was raised previously and addressed here. By patch clamping hypocotyl cells isolated from dark-grown (etiolated) Arabidopsis seedlings, blue light was found to activate an anion channel residing at the plasma membrane. An anion-channel blocker commonly known as NPPB 15-nitro-2-(3-phenylpropylamino)-benzoic acid] potently and reversibly blocked this anion channel. NPPB also blocked the blue-light-induced depolarization in vivo and decreased the inhibitory effect of blue light on hypocotyl elongation. These results indicate that activation of this anion channel plays a role in transducing blue light into growth inhibition.

  20. Clinical and histological effects of blue light on normal skin.

    NARCIS (Netherlands)

    Kleinpenning, M.M.; Smits, T.; Frunt, M.H.A.; Erp, P.E.J. van; Kerkhof, P.C.M. van de; Gerritsen, R.M.

    2010-01-01

    INTRODUCTION: Phototherapy with visible light is gaining interest in dermatological practice. Theoretically, blue light could induce biological effects comparable to ultraviolet A (UVA) radiation. OBJECTIVES: To study the effects of blue light on normal skin in terms of photodamage, skin ageing and

  1. Light Absorbing Aerosols in Mexico City

    Science.gov (United States)

    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.

  2. Blue light-induced oxidative stress in live skin.

    Science.gov (United States)

    Nakashima, Yuya; Ohta, Shigeo; Wolf, Alexander M

    2017-07-01

    Skin damage from exposure to sunlight induces aging-like changes in appearance and is attributed to the ultraviolet (UV) component of light. Photosensitized production of reactive oxygen species (ROS) by UVA light is widely accepted to contribute to skin damage and carcinogenesis, but visible light is thought not to do so. Using mice expressing redox-sensitive GFP to detect ROS, blue light could produce oxidative stress in live skin. Blue light induced oxidative stress preferentially in mitochondria, but green, red, far red or infrared light did not. Blue light-induced oxidative stress was also detected in cultured human keratinocytes, but the per photon efficacy was only 25% of UVA in human keratinocyte mitochondria, compared to 68% of UVA in mouse skin. Skin autofluorescence was reduced by blue light, suggesting flavins are the photosensitizer. Exposing human skin to the blue light contained in sunlight depressed flavin autofluorescence, demonstrating that the visible component of sunlight has a physiologically significant effect on human skin. The ROS produced by blue light is probably superoxide, but not singlet oxygen. These results suggest that blue light contributes to skin aging similar to UVA. Copyright © 2017 Elsevier Inc. All rights reserved.

  3. Effects of blue light and caffeine on mood.

    Science.gov (United States)

    Ekström, Johan G; Beaven, C Martyn

    2014-09-01

    Both short wavelength (blue) light and caffeine have been studied for their mood enhancing effects on humans. The ability of blue light to increase alertness, mood and cognitive function via non-image forming neuropathways has been suggested as a non-pharmacological countermeasure for depression across a range of occupational settings. This experimental study compared blue light and caffeine and aimed to test the effects of blue light/placebo (BLU), white light/240-mg caffeine (CAF), blue light/240-mg caffeine (BCAF) and white light/placebo (PLA), on mood. A randomised, controlled, crossover design study was used, in a convenience population of 20 healthy volunteers. The participants rated their mood on the Swedish Core Affect Scales (SCAS) prior to and after each experimental condition to assess the dimensions of valence and activation. There was a significant main effect of light (p = 0.009), and the combination of blue light and caffeine had clear positive effects on core effects (ES, ranging from 0.41 to 1.20) and global mood (ES, 0.61 ± 0.53). The benefits of the combination of blue light and caffeine should be further investigated across a range of applications due to the observed effects on the dimensions of arousal, valence and pleasant activation.

  4. Phototropin 1 and dim-blue light modulate the red light de-etiolation response.

    Science.gov (United States)

    Wang, Yihai; M Folta, Kevin

    2014-01-01

    Light signals regulate seedling morphological changes during de-etiolation through the coordinated actions of multiple light-sensing pathways. Previously we have shown that red-light-induced hypocotyl growth inhibition can be reversed by addition of dim blue light through the action of phototropin 1 (phot1). Here we further examine the fluence-rate relationships of this blue light effect in short-term (hours) and long-term (days) hypocotyl growth assays. The red stem-growth inhibition and blue promotion is a low-fluence rate response, and blue light delays or attenuates both the red light and far-red light responses. These de-etiolation responses include blue light reversal of red or far-red induced apical hook opening. This response also requires phot1. Cryptochromes (cry1 and cry2) are activated by higher blue light fluence-rates and override phot1's influence on hypocotyl growth promotion. Exogenous application of auxin transport inhibitor naphthylphthalamic acid abolished the blue light stem growth promotion in both hypocotyl growth and hook opening. Results from the genetic tests of this blue light effect in auxin transporter mutants, as well as phytochrome kinase substrate mutants indicated that aux1 may play a role in blue light reversal of red light response. Together, the phot1-mediated adjustment of phytochrome-regulated photomorphogenic events is most robust in dim blue light conditions and is likely modulated by auxin transport through its transporters.

  5. Blue-green and green phosphors for lighting applications

    Science.gov (United States)

    Setlur, Anant Achyut; Chandran, Ramachandran Gopi; Henderson, Claire Susan; Nammalwar, Pransanth Kumar; Radkov, Emil

    2012-12-11

    Embodiments of the present techniques provide a related family of phosphors that may be used in lighting systems to generate blue or blue-green light. The phosphors include systems having a general formula of: ((Sr.sub.1-zM.sub.z).sub.1-(x+w)A.sub.wCe.sub.x).sub.3(Al.sub.1-ySi.s- ub.y)O.sub.4+y+3(x-w)F.sub.1-y-3(x-w) (I), wherein 0lighting systems, such as LEDs and fluorescent tubes, among others, to produce blue and blue/green light. Further, the phosphors may be used in blends with other phosphors, or in combined lighting systems, to produce white light suitable for illumination.

  6. Biological behaviour of buccal cells exposed to blue light

    International Nuclear Information System (INIS)

    Gritsch, Kerstin; Ponsonnet, Laurence; Schembri, Catherine; Farge, Pierre; Pourreyron, Laurence; Grosgogeat, Brigitte

    2008-01-01

    Blue light is used in dental practise to cure resin-based materials, but the path of the light often includes oral tissues such as gingival tissues. While adverse effects of blue light exposure on cells - such as retina cells - are well known, few studies have investigated the impact of blue light exposure on oral cells. The aim of the present in vitro study was to assess the biological effects of blue light emitted by two dental curing devices (a plasma-arc and a light-emitting diode curing unit) on human gingival fibroblasts. Light intensities and light-induced temperature rise were respectively measured with a radiometer and a thermocouple. Cellular response to blue light exposure was assessed by the observation of cell morphology (scanning electron microscopy) and the estimation of cell mitochondrial activity (MTT assay). Light intensities measured at the clinical distance were 488 ± 42 mW/cm 2 for the plasma-arc unit and ranged from 61 ± 5 to 140 ± 16 mW/cm 2 for the light-emitting diodes unit, according to the curing program used. The highest temperature rise was 0.5 and 3.5 deg. C for exposure to the plasma-arc light and to the light-emitting diodes light, respectively. Results showed no differences between exposed- and non-exposed cells in regards to cell morphology. However, cells exposed to blue light presented an increased mitochondrial activity compared to control cells (non-exposed), and mostly those exposed to plasma-arc light

  7. Phototherapy with blue and green mixed-light is as effective against unconjugated jaundice as blue light and reduces oxidative stress in the Gunn rat model.

    Science.gov (United States)

    Uchida, Yumiko; Morimoto, Yukihiro; Uchiike, Takao; Kamamoto, Tomoyuki; Hayashi, Tamaki; Arai, Ikuyo; Nishikubo, Toshiya; Takahashi, Yukihiro

    2015-07-01

    Phototherapy using blue light-emitting diodes (LED) is effective against neonatal jaundice. However, green light phototherapy also reduces unconjugated jaundice. We aimed to determine whether mixed blue and green light can relieve jaundice with minimal oxidative stress as effectively as either blue or green light alone in a rat model. Gunn rats were exposed to phototherapy with blue (420-520 nm), filtered blue (FB; 440-520 nm without 1.00), respectively. Blue plus green phototherapy is as effective as blue phototherapy and it attenuates irradiation-induced oxidative stress. Combined blue and green spectra might be effective against neonatal hyperbilirubinemia. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

  8. Phototherapy with blue and green mixed-light is as effective against unconjugated jaundice as blue light and reduces oxidative stress in the Gunn rat model.

    OpenAIRE

    Uchida, Yumiko; Morimoto, Yukihiro; Uchiike, Takao; Kamamoto, Tomoyuki :4/0000339; Hayashi, Tamaki; Arai, Ikuyo; Nishikubo, Toshiya; Takahashi, Yukihiro

    2015-01-01

    OBJECTIVE:Phototherapy using blue light-emitting diodes (LED) is effective against neonatal jaundice. However, green light phototherapy also reduces unconjugated jaundice. We aimed to determine whether mixed blue and green light can relieve jaundice with minimal oxidative stress as effectively as either blue or green light alone in a rat model.METHODS:Gunn rats were exposed to phototherapy with blue (420-520 nm), filtered blue (FB; 440-520 nm without

  9. Blue light hazards for ocular lesions; Risques oculaires du rayonnement bleu

    Energy Technology Data Exchange (ETDEWEB)

    Cesarini, J.P. [INSERM, Fondation Ophtalmologique A. de Rothschild, 75 - Paris (France); CES, Agents physique, AFSSET (France)

    2009-10-15

    The blue light range (400-500 nm) of visible radiation stimulates specifically cones and rods of the retina. The carried energy by these wavelengths is absorbed and transferred to specific pigments. Their energy is sufficient to produce free radicals and singlet form of oxygen. Intense sources, rich in blue light radiation, may induce, in the retina, photo-toxic lesions either limited or short-lived or photothermal lesions more or less definitive. Repeated photo-toxic lesions should be the root for the age-related maculo-pathy (A.R.M.) also called late macular degeneration (A.M.D.). As a consequence, the attention should be drawn on the potential risk linked to modern lighting as 'daylight' lamp, compact fluorescent lamps, energy saving (C.F.L.) and light-emitting diodes (L.E.D.) for which a specific vigilance should be enforced. (author)

  10. Blue-light emitting triazolopyridinium and triazoloquinolinium salts

    KAUST Repository

    Carboni, Valentina

    2017-01-27

    Compounds that emit blue light are of interest for applications that include optoelectronic devices and chemo/biosensing and imaging. The design and synthesis of small organic molecules that can act as high-efficiency deep-blue-light emitters in the solid state and can be easily processed from solutions represents a significant challenge. Herein we present the preparation and photophysical, photochemical and electrochemical properties of a series of triazolopyridinium and triazoloquinolinium compounds. The compounds are soluble in water or polar organic solvents and exhibit photoluminescence in the blue region of the spectrum in fluid solution, in the solid state and in a frozen matrix.

  11. Metal–insulator–metal light absorber: a continuous structure

    International Nuclear Information System (INIS)

    Yan, M

    2013-01-01

    A type of light absorber made of continuous layers of metal and dielectric films is studied. The metal films can have thicknesses close to their skin depths in the wavelength range concerned, which allows for both light transmission and reflection. Resonances induced by multiple reflections in the structure, when combined with the inherent lossy nature of metals, result in strong absorption spectral features. An eigen-mode analysis is carried out for the plasmonic multilayer nanostructures which provides a generic understanding of the absorption features. Experimentally, the calculation is verified by a reflection measurement with a representative structure. Such an absorber is simple to fabricate. The highly efficient absorption characteristics can be potentially deployed for optical filter designs, sensors, accurate photothermal temperature control in a micro-environment and even for backscattering reduction of small particles, etc. (paper)

  12. Blue light dosage affects carotenoids and tocopherols in microgreens.

    Science.gov (United States)

    Samuolienė, Giedrė; Viršilė, Akvilė; Brazaitytė, Aušra; Jankauskienė, Julė; Sakalauskienė, Sandra; Vaštakaitė, Viktorija; Novičkovas, Algirdas; Viškelienė, Alina; Sasnauskas, Audrius; Duchovskis, Pavelas

    2017-08-01

    Mustard, beet and parsley were grown to harvest time under selected LEDs: 638+660+731+0% 445nm; 638+660+731+8% 445nm; 638+660+731+16% 445nm; 638+660+731+25% 445nm; 638+660+731+33% 445nm. From 1.2 to 4.3 times higher concentrations of chlorophylls a and b, carotenoids, α- and β-carotenes, lutein, violaxanthin and zeaxanthin was found under blue 33% treatment in comparison to lower blue light dosages. Meanwhile, the accumulation of metabolites, which were not directly connected with light reactions, such as tocopherols, was more influenced by lower (16%) blue light dosage, increasing about 1.3 times. Thus, microgreen enrichment of carotenoid and xanthophyll pigments may be achieved using higher (16-33%) blue light intensities. Changes in metabolite quantities were not the result of changes of other carotenoid concentration, but were more influenced by light treatment and depended on the species. Significant quantitative changes in response to blue light percentage were obtained for both directly and not directly light-dependent metabolite groups. Copyright © 2017 Elsevier Ltd. All rights reserved.

  13. A Flavin Binding Cryptochrome Photoreceptor Responds to Both Blue and Red Light in Chlamydomonas reinhardtii[W

    Science.gov (United States)

    Beel, Benedikt; Prager, Katja; Spexard, Meike; Sasso, Severin; Weiss, Daniel; Müller, Nico; Heinnickel, Mark; Dewez, David; Ikoma, Danielle; Grossman, Arthur R.; Kottke, Tilman; Mittag, Maria

    2012-01-01

    Cryptochromes are flavoproteins that act as sensory blue light receptors in insects, plants, fungi, and bacteria. We have investigated a cryptochrome from the green alga Chlamydomonas reinhardtii with sequence homology to animal cryptochromes and (6-4) photolyases. In response to blue and red light exposure, this animal-like cryptochrome (aCRY) alters the light-dependent expression of various genes encoding proteins involved in chlorophyll and carotenoid biosynthesis, light-harvesting complexes, nitrogen metabolism, cell cycle control, and the circadian clock. Additionally, exposure to yellow but not far-red light leads to comparable increases in the expression of specific genes; this expression is significantly reduced in an acry insertional mutant. These in vivo effects are congruent with in vitro data showing that blue, yellow, and red light, but not far-red light, are absorbed by the neutral radical state of flavin in aCRY. The aCRY neutral radical is formed following blue light absorption of the oxidized flavin. Red illumination leads to conversion to the fully reduced state. Our data suggest that aCRY is a functionally important blue and red light–activated flavoprotein. The broad spectral response implies that the neutral radical state functions as a dark form in aCRY and expands the paradigm of flavoproteins and cryptochromes as blue light sensors to include other light qualities. PMID:22773746

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

  15. How to distinguish scattered and absorbed light from re-emitted light for white LEDs?

    NARCIS (Netherlands)

    Meretska, Maryna; Lagendijk, Aart; Thyrrestrup Nielsen, Henri; Mosk, Allard; IJzerman, Wilbert; Vos, Willem L.

    2017-01-01

    We have studied the light transport through phosphor diffuser plates that are used in commercial solid-state lighting modules (Fortimo). These polymer plates contain YAG:Ce+3 phosphor particles that scatter, absorb and re-emit incident light in the visible wavelength range (400-700 nm). To

  16. Light Absorbers and Catalysts for Solar to Fuel Conversion

    Science.gov (United States)

    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

  17. The Effects of Blue Light on Ocular Health.

    Science.gov (United States)

    Kitchel, Elaine

    2000-01-01

    This review of the literature examines the effects of blue light (or near UV - ultraviolet), especially that given off by black-light tubes, often used with children with visual impairments. It finds a long-term danger of retinal and lens damage and offers six practical suggestions which emphasize using proper filters and limiting exposure to…

  18. Blue-Light Filtering Spectacle Lenses: Optical and Clinical Performances.

    Science.gov (United States)

    Leung, Tsz Wing; Li, Roger Wing-Hong; Kee, Chea-Su

    2017-01-01

    To evaluate the optical performance of blue-light filtering spectacle lenses and investigate whether a reduction in blue light transmission affects visual performance and sleep quality. Experiment 1: The relative changes in phototoxicity, scotopic sensitivity, and melatonin suppression of five blue-light filtering plano spectacle lenses were calculated based on their spectral transmittances measured by a spectrophotometer. Experiment 2: A pseudo-randomized controlled study was conducted to evaluate the clinical performance of two blue-light filtering spectacle lenses (BF: blue-filtering anti-reflection coating; BT: brown-tinted) with a regular clear lens (AR) serving as a control. A total of eighty computer users were recruited from two age cohorts (young adults: 18-30 yrs, middle-aged adults: 40-55 yrs). Contrast sensitivity under standard and glare conditions, and colour discrimination were measured using standard clinical tests. After one month of lens wear, subjective ratings of lens performance were collected by questionnaire. All tested blue-light filtering spectacle lenses theoretically reduced the calculated phototoxicity by 10.6% to 23.6%. Although use of the blue-light filters also decreased scotopic sensitivity by 2.4% to 9.6%, and melatonin suppression by 5.8% to 15.0%, over 70% of the participants could not detect these optical changes. Our clinical tests revealed no significant decrease in contrast sensitivity either with (95% confidence intervals [CI]: AR-BT [-0.05, 0.05]; AR-BF [-0.05, 0.06]; BT-BF [-0.06, 0.06]) or without glare (95% CI: AR-BT [-0.01, 0.03]; AR-BF [-0.01, 0.03]; BT-BF [-0.02, 0.02]) and colour discrimination (95% CI: AR-BT [-9.07, 1.02]; AR-BF [-7.06, 4.46]; BT-BF [-3.12, 8.57]). Blue-light filtering spectacle lenses can partially filter high-energy short-wavelength light without substantially degrading visual performance and sleep quality. These lenses may serve as a supplementary option for protecting the retina from potential

  19. Blue-Light Filtering Spectacle Lenses: Optical and Clinical Performances

    Science.gov (United States)

    2017-01-01

    Purposes To evaluate the optical performance of blue-light filtering spectacle lenses and investigate whether a reduction in blue light transmission affects visual performance and sleep quality. Methods Experiment 1: The relative changes in phototoxicity, scotopic sensitivity, and melatonin suppression of five blue-light filtering plano spectacle lenses were calculated based on their spectral transmittances measured by a spectrophotometer. Experiment 2: A pseudo-randomized controlled study was conducted to evaluate the clinical performance of two blue-light filtering spectacle lenses (BF: blue-filtering anti-reflection coating; BT: brown-tinted) with a regular clear lens (AR) serving as a control. A total of eighty computer users were recruited from two age cohorts (young adults: 18–30 yrs, middle-aged adults: 40–55 yrs). Contrast sensitivity under standard and glare conditions, and colour discrimination were measured using standard clinical tests. After one month of lens wear, subjective ratings of lens performance were collected by questionnaire. Results All tested blue-light filtering spectacle lenses theoretically reduced the calculated phototoxicity by 10.6% to 23.6%. Although use of the blue-light filters also decreased scotopic sensitivity by 2.4% to 9.6%, and melatonin suppression by 5.8% to 15.0%, over 70% of the participants could not detect these optical changes. Our clinical tests revealed no significant decrease in contrast sensitivity either with (95% confidence intervals [CI]: AR–BT [–0.05, 0.05]; AR–BF [–0.05, 0.06]; BT–BF [–0.06, 0.06]) or without glare (95% CI: AR–BT [–0.01, 0.03]; AR–BF [–0.01, 0.03]; BT–BF [–0.02, 0.02]) and colour discrimination (95% CI: AR–BT [–9.07, 1.02]; AR–BF [–7.06, 4.46]; BT–BF [–3.12, 8.57]). Conclusion Blue-light filtering spectacle lenses can partially filter high-energy short-wavelength light without substantially degrading visual performance and sleep quality. These lenses may

  20. Effects of blue light on pigment biosynthesis of Monascus.

    Science.gov (United States)

    Chen, Di; Xue, Chunmao; Chen, Mianhua; Wu, Shufen; Li, Zhenjing; Wang, Changlu

    2016-04-01

    The influence of different illumination levels of blue light on the growth and intracellular pigment yields of Monascus strain M9 was investigated. Compared with darkness, constant exposure to blue light of 100 lux reduced the yields of six pigments, namely, rubropunctatamine (RUM), monascorubramine (MOM), rubropunctatin (RUN), monascorubrin (MON), monascin (MS), and ankaflavin (AK). However, exposure to varying levels of blue light had different effects on pigment production. Exposure to 100 lux of blue light once for 30 min/day and to 100 lux of blue light once and twice for 15 min/day could enhance RUM, MOM, MS, and AK production and reduce RUN and MON compared with non-exposure. Exposure to 100 lux twice for 30 min/day and to 200 lux once for 45 min/day decreased the RUM, MOM, MS, and AK yields and increased the RUN and MON. Meanwhile, the expression levels of pigment biosynthetic genes were analyzed by real-time quantitative PCR. Results indicated that gene MpPKS5, mppR1, mppA, mppB, mmpC, mppD, MpFasA, MpFasB, and mppF were positively correlated with the yields of RUN and MON, whereas mppE and mppR2 were associated with RUM, MOM, MS, and AK production.

  1. Blue light does not impair wound healing in vitro.

    Science.gov (United States)

    Masson-Meyers, Daniela Santos; Bumah, Violet Vakunseh; Enwemeka, Chukuka Samuel

    2016-07-01

    Irradiation with red or near infrared light promotes tissue repair, while treatment with blue light is known to be antimicrobial. Consequently, it is thought that infected wounds could benefit more from combined blue and red/infrared light therapy; but there is a concern that blue light may slow healing. We investigated the effect of blue 470nm light on wound healing, in terms of wound closure, total protein and collagen synthesis, growth factor and cytokines expression, in an in vitro scratch wound model. Human dermal fibroblasts were cultured for 48h until confluent. Then a linear scratch wound was created and irradiated with 3, 5, 10 or 55J/cm(2). Control plates were not irradiated. Following 24h of incubation, cells were fixed and stained for migration and fluorescence analyses and the supernatant collected for quantification of total protein, hydroxyproline, bFGF, IL-6 and IL-10. The results showed that wound closure was similar for groups treated with 3, 5 and 10J/cm(2), with a slight improvement with the 5J/cm(2) dose, and slower closure with 55J/cm(2) pblue light at low fluence does not impair in vitro wound healing. The significant decrease in IL-6 suggests that 470nm light is anti-inflammatory. Copyright © 2016 Elsevier B.V. All rights reserved.

  2. Stable blue phosphorescent organic light emitting devices

    Science.gov (United States)

    Forrest, Stephen R.; Thompson, Mark; Giebink, Noel

    2014-08-26

    Novel combination of materials and device architectures for organic light emitting devices is provided. An organic light emitting device, is provided, having an anode, a cathode, and an emissive layer disposed between the anode and the cathode. The emissive layer includes a host and a phosphorescent emissive dopant having a peak emissive wavelength less than 500 nm, and a radiative phosphorescent lifetime less than 1 microsecond. Preferably, the phosphorescent emissive dopant includes a ligand having a carbazole group.

  3. Blue and ultraviolet-B light photoreceptors in parsley cells

    Energy Technology Data Exchange (ETDEWEB)

    Ensminger, P.A.; Schaefer, E. (Albert-Ludwigs-Univ., Freiburg (Germany). Inst. fuer Biologie II)

    1992-03-01

    The authors studied UV-B photoreception in parsley cell cultures with physiological experiments involving temperature shifts and examined the possible role of flavin in blue and UV-B light photo-reception. Cells irradiated with UV-B light (0.5-15 min) at 2{sup o}C have the same fluence requirement for chalcone synthase and flavonoid induction as controls irradiated at 25{sup o}C. This is indicative of a purely photochemical reaction. Cells fed with riboflavin and irradiated with 6 h of UV-containing white light synthesize higher levels of chalcone synthase and flavonoid than unfed controls. This effect did not occur with blue light. These results indicate that flavin-sensitization requires excitation of flavin and the UV-B light photoreceptor. (author).

  4. Blue laser diode (LD) and light emitting diode (LED) applications

    International Nuclear Information System (INIS)

    Bergh, Arpad A.

    2004-01-01

    The family of blue LEDs, edge emitting and surface emitting lasers, enable a number of applications. Blue lasers are used in digital applications such as optical storage in high density DVDs. The resolution of the spot size and hence the storage density is diffraction limited and is inversely proportional to the square of the wavelength of the laser. Other applications include printing, optical scanners, and high-resolution photo-lithography. As light emitters, blue LEDs are used for signaling and in direct view large area emissive displays. They are also making inroads into signage and LCD back-lighting, mobile platforms, and decorative accent lighting in curtains, furniture, etc. Blue LEDs produce white light either with phosphor wavelength converters or in combination with red and green LEDs. The full potential of LED light sources will require three devices to enable complete control over color and intensity. Sensing and medical/bio applications have a major impact on home security, on monitoring the environment, and on health care. New emerging diagnostic and therapeutic applications will improve the quality and reduce the cost of health care. (copyright 2004 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  5. Blue light reduces organ injury from ischemia and reperfusion

    Science.gov (United States)

    Yuan, Du; Collage, Richard D.; Huang, Hai; Zhang, Xianghong; Kautza, Benjamin C.; Lewis, Anthony J.; Zuckerbraun, Brian S.; Tsung, Allan; Angus, Derek C.; Rosengart, Matthew R.

    2016-01-01

    Evidence suggests that light and circadian rhythms profoundly influence the physiologic capacity with which an organism responds to stress. However, the ramifications of light spectrum on the course of critical illness remain to be determined. Here, we show that acute exposure to bright blue spectrum light reduces organ injury by comparison with bright red spectrum or ambient white fluorescent light in two murine models of sterile insult: warm liver ischemia/reperfusion (I/R) and unilateral renal I/R. Exposure to bright blue light before I/R reduced hepatocellular injury and necrosis and reduced acute kidney injury and necrosis. In both models, blue light reduced neutrophil influx, as evidenced by reduced myeloperoxidase (MPO) within each organ, and reduced the release of high-mobility group box 1 (HMGB1), a neutrophil chemotactant and key mediator in the pathogenesis of I/R injury. The protective mechanism appeared to involve an optic pathway and was mediated, in part, by a sympathetic (β3 adrenergic) pathway that functioned independent of significant alterations in melatonin or corticosterone concentrations to regulate neutrophil recruitment. These data suggest that modifying the spectrum of light may offer therapeutic utility in sterile forms of cellular injury. PMID:27114521

  6. Cellular effects of halogen blue light from dental curing unit

    International Nuclear Information System (INIS)

    Trosic, I.; Pavicic, I.; Jukic, S.

    2008-01-01

    Full text: Halogen curing lights are the most frequently used polymerization source in dental offices. Light-cured bonding systems have become increasingly popular among clinicians because they offer a number of advantages over self-cured adhesives. The effort to increase polymerization quality releases the commercially available high power light density dental curing units. Emitted visible blue light belongs to the range of nonionizing radiation. Common concern in both, patients and dentist grows with regard to the unfavorable effects on the pulp tissue. The aim of study was to evaluate the time and dose dependence effect of halogen light curing unit (Elipar TriLight, ESPE Dental AG, Germany) at the disposed condition modes in vitro. A quartz-tungsten-halogen light source emits radiation of the wavelengths between 400 and 515 nm. This halogen blue light source operates in the three illumination modes, medium (M), exponential (E) and standard (S), and five illumination times. The total irradiance or the light intensity was measured by the light intensity control area on the control panel of device and mean light intensity given by manufacturer was 800 m W/cm 2 . Continuous culture of V79 cells was illuminated in triplicate. The influence of medium mode (M), exponential (E) and standard (S) illumination during 20, 40 and 80 sec on the cell viability, colony forming ability and proliferation of V79 cell culture was investigated. Trypan blue exclusion test was used to determine cell viability, both, in the treated and control cell samples. Colony forming ability was assessed for each exposure time and mode by colony count on post-exposure day 7. Cell proliferation was determined by cell counts for each time and mode of exposure during five post-exposure days. Statistical difference were determined at p<0.05 (Statistica 7.0, StatSoft Inc., USA). Viability of cells was not affected by blue light in view of exposure time and modes. Regardless to exposure or illumination

  7. Green-light supplementation for enhanced lettuce growth under red- and blue-light-emitting diodes

    Science.gov (United States)

    Kim, Hyeon-Hye; Goins, Gregory D.; Wheeler, Raymond M.; Sager, John C.

    2004-01-01

    Plants will be an important component of future long-term space missions. Lighting systems for growing plants will need to be lightweight, reliable, and durable, and light-emitting diodes (LEDs) have these characteristics. Previous studies demonstrated that the combination of red and blue light was an effective light source for several crops. Yet the appearance of plants under red and blue lighting is purplish gray making visual assessment of any problems difficult. The addition of green light would make the plant leave appear green and normal similar to a natural setting under white light and may also offer a psychological benefit to the crew. Green supplemental lighting could also offer benefits, since green light can better penetrate the plant canopy and potentially increase plant growth by increasing photosynthesis from the leaves in the lower canopy. In this study, four light sources were tested: 1) red and blue LEDs (RB), 2) red and blue LEDs with green fluorescent lamps (RGB), 3) green fluorescent lamps (GF), and 4) cool-white fluorescent lamps (CWF), that provided 0%, 24%, 86%, and 51% of the total PPF in the green region of the spectrum, respectively. The addition of 24% green light (500 to 600 nm) to red and blue LEDs (RGB treatment) enhanced plant growth. The RGB treatment plants produced more biomass than the plants grown under the cool-white fluorescent lamps (CWF treatment), a commonly tested light source used as a broad-spectrum control.

  8. Blue Light Delays Commitment to Cell Division in Chlamydomonas Reinhardtii

    Czech Academy of Sciences Publication Activity Database

    Oldenhof, H.; Zachleder, Vilém; van den Ende, H.

    2004-01-01

    Roč. 6, - (2004), s. 689-695 ISSN 1435-8603 Institutional research plan: CEZ:AV0Z5020903 Keywords : Blue light * Cell cycle * Cell volume Subject RIV: EE - Microbiology, Virology Impact factor: 1.582, year: 2004

  9. Blue light (470 nm) effectively inhibits bacterial and fungal growth

    Science.gov (United States)

    The activity of blue light (470nm) alone on (1) bacterial viability, and (2) with a food grade photosensitizer on filamentous fungal viability, was studied. Suspensions of the bacteria Leuconostoc mesenteroides (LM), Bacillus atrophaeus (BA), and Pseudomonas aeruginosa (PA) were prepared and aliquo...

  10. Supporting Information Blue and White light electroluminescence in ...

    Indian Academy of Sciences (India)

    Administrator

    Blue and White light electroluminescence in a multilayer OLED using a new Aluminium complex. Pabitra K. Nayak a. , Neeraj Agarwal a. , Farman Ali a. , Meghan P. Patankar b. , K. L.. Narasimhan b. *, N. Periasamy a. *. 1. Department of Chemical Sciences,. 2. Department of Condensed Matter Physics and. Materials ...

  11. Melanocytes Sense Blue Light and Regulate Pigmentation through Opsin-3.

    Science.gov (United States)

    Regazzetti, Claire; Sormani, Laura; Debayle, Delphine; Bernerd, Françoise; Tulic, Meri K; De Donatis, Gian Marco; Chignon-Sicard, Bérengère; Rocchi, Stéphane; Passeron, Thierry

    2018-01-01

    The shorter wavelengths of the visible light spectrum have been recently reported to induce a long-lasting hyperpigmentation but only in melano-competent individuals. Here, we provide evidence showing that OPN3 is the key sensor in melanocytes responsible for hyperpigmentation induced by the shorter wavelengths of visible light. The melanogenesis induced through OPN3 is calcium dependent and further activates CAMKII followed by CREB, extracellular signal-regulated kinase, and p38, leading to the phosphorylation of MITF and ultimately to the increase of the melanogenesis enzymes: tyrosinase and dopachrome tautomerase. Furthermore, blue light induces the formation of a protein complex that we showed to be formed by tyrosinase and dopachrome tautomerase. This multimeric tyrosinase/tyrosinase-related protein complex is mainly formed in dark-skinned melanocytes and induces a sustained tyrosinase activity, thus explaining the long-lasting hyperpigmentation that is observed only in skin type III and higher after blue light irradiation. OPN3 thus functions as the sensor for visible light pigmentation. OPN3 and the multimeric tyrosinase/tyrosinase-related protein complex induced after its activation appear as new potential targets for regulating melanogenesis but also to protect dark skins against blue light in physiological conditions and in pigmentary disorders. Copyright © 2017 The Authors. Published by Elsevier Inc. All rights reserved.

  12. [Blue light hazards associated with crystal glassware production].

    Science.gov (United States)

    Okuno, Tsutomu; Ueno, Satoru; Kobayashi, Yuuichi; Kozu, Susumu

    2013-01-01

    In factories for glassware production, workers are exposed to intense visible light emitted from hot objects such as furnaces and molten glass. High exposure to short-wavelength visible light, called blue light, can cause photoretinopathy. The objective of this study was to quantify the blue-light hazards associated with glassware production. Spectral radiances of walls and heating elements inside furnaces were measured, as well as those of molten glass placed inside furnaces in a factory producing crystal glass crafts. The factory had two reheating furnaces, three melting furnaces, and a furnace for preheating blowpipes. The effective radiances of the inner furnace walls, the heating elements, and the molten glass were calculated from the measured spectral radiances and compared with the threshold limit value (TLV) in accordance with ACGIH guidelines. The temperature of each light source was determined by comparing the measured spectral radiance with that of a black body. The measured effective radiances were in the range of 0.00498-0.708 mW/cm(2)sr and increased steeply with increasing light source temperatures in the range of 1,075-1,516 °C. The effective radiance of each light source was nearly equal to the effective radiance of the black body at the same temperature. The effective radiances of walls, heating elements, and molten glass inside the furnaces are lower than one tenth of the TLV for exposure durations longer than 10(4) s per day. Thus, it is not hazardous to view these light sources. However, the effective radiance at a higher light source temperature of approximately 1,800 °C will exceed the TLV. In this case, hot objects in a workplace for glassware production may present blue light hazards.

  13. Blue and white light emission from zinc oxide nanoforests

    Directory of Open Access Journals (Sweden)

    Nafisa Noor

    2015-12-01

    Full Text Available Blue and white light emission is observed when high voltage stress is applied using micrometer-separated tungsten probes across a nanoforest formed of ZnO nanorods. The optical spectrum of the emitted light consistently shows three fine peaks with very high amplitude in the 465–485 nm (blue range, corresponding to atomic transitions of zinc. Additional peaks with smaller amplitudes in the 330–650 nm range and broad spectrum white light is observed depending on the excitation conditions. The spatial and spectral distribution of the emitted light, with pink–orange regions identifying percolation paths in some cases and high intensity blue and white light with center to edge variations in others, indicate that multiple mechanisms lead to light emission. Under certain conditions, the tungsten probe tips used to make electrical contact with the ZnO structures melt during the excitation, indicating that the local temperature can exceed 3422 °C, which is the melting temperature of tungsten. The distinct and narrow peaks in the optical spectra and the abrupt increase in current at high electric fields suggest that a plasma is formed by application of the electrical bias, giving rise to light emission via atomic transitions in gaseous zinc and oxygen. The broad spectrum, white light emission is possibly due to the free electron transitions in the plasma and blackbody radiation from molten silicon. The white light may also arise from the recombination through multiple defect levels in ZnO or due to the optical excitation from solid ZnO. The electrical measurements performed at different ambient pressures result in light emission with distinguishable differences in the emission properties and I–V curves, which also indicate that the dielectric breakdown of ZnO, sublimation, and plasma formation processes are the underlying mechanisms.

  14. [Study on the safety of blue light leak of LED].

    Science.gov (United States)

    Shen, Chong-Yu; Xu, Zheng; Zhao, Su-Ling; Huang, Qing-Yu

    2014-02-01

    In this paper, the blue light properties of LED illumination devices have been investigated. Against the status quo of China's LED lighting, we measured the spectrum component of LED lamps and analyzed the photobiological safety under the current domestic and international standards GB/T 20145-2006/CIE S009/E: 2002 and IEC62471: 2006 standards as well as CTL-0744_2009-laser resolution, which provides the reference to the manufacture of LED lighting lamps as well as related safety standards and laws. If the radiance intensity of blue light in LED is lower than 100 W x m(-2) x Sr(-1), there is no harm to human eyes. LEDs will not cause harm to human eyes under normal use, but we should pay attention to the protection of special populations (children), and make sure that they avoid looking at a light source for a long time. The research has found that the blue-rich lamps can affect the human rule of work and rest, and therefore, the LED lamps with color temperature below 4 000 K and color rendering index of 80 are suitable for indoor use. At the same time, the lamps with different parameters should be selected according to the different distances.

  15. Blue light emitting diesel soot for photonic applications

    Science.gov (United States)

    Swapna, M. S.; Sankararaman, S.

    2018-01-01

    The present work is the first report of producing blue light emission from phosphor free and low-cost material—the diesel soot from the internal combustion engines (ICEs). The structural morphology is analyzed by field emission scanning electron microscopy and high-resolution transmission electron microscopy. The optical characterization is done by recording UV–visible spectrum and photoluminescent Spectrum. The CIE plot and the power spectrum for the sample show blue emission. This is further verified by collecting diesel soot from the ICE of different year of make. A visual confirmation of blue emission is obtained by exciting the sample with UV laser. The presence of various allotropic forms of carbon in the sample is identified by x-ray diffraction, Fourier transform infrared and Raman spectroscopic analysis.

  16. Blue light effect on retinal pigment epithelial cells by display devices.

    Science.gov (United States)

    Moon, Jiyoung; Yun, Jieun; Yoon, Yeo Dae; Park, Sang-Il; Seo, Young-Jun; Park, Won-Sang; Chu, Hye Yong; Park, Keun Hong; Lee, Myung Yeol; Lee, Chang Woo; Oh, Soo Jin; Kwak, Young-Shin; Jang, Young Pyo; Kang, Jong Soon

    2017-05-22

    Blue light has high photochemical energy and induces cell apoptosis in retinal pigment epithelial cells. Due to its phototoxicity, retinal hazard by blue light stimulation has been well demonstrated using high intensity light sources. However, it has not been studied whether blue light in the displays, emitting low intensity light, such as those used in today's smartphones, monitors, and TVs, also causes apoptosis in retinal pigment epithelial cells. We attempted to examine the blue light effect on human adult retinal epithelial cells using display devices with different blue light wavelength ranges, the peaks of which specifically appear at 449 nm, 458 nm, and 470 nm. When blue light was illuminated on A2E-loaded ARPE-19 cells using these displays, the display with a blue light peak at a shorter wavelength resulted in an increased production of reactive oxygen species (ROS). Moreover, the reduction of cell viability and induction of caspase-3/7 activity were more evident in A2E-loaded ARPE-19 cells after illumination by the display with a blue light peak at a shorter wavelength, especially at 449 nm. Additionally, white light was tested to examine the effect of blue light in a mixed color illumination with red and green lights. Consistent with the results obtained using only blue light, white light illuminated by display devices with a blue light peak at a shorter wavelength also triggered increased cell death and apoptosis compared to that illuminated by display devices with a blue light peak at longer wavelength. These results show that even at the low intensity utilized in the display devices, blue light can induce ROS production and apoptosis in retinal cells. Our results also suggest that the blue light hazard of display devices might be highly reduced if the display devices contain less short wavelength blue light.

  17. Blue Light Emitting Polyphenylene Dendrimers with Bipolar Charge Transport Moieties

    Directory of Open Access Journals (Sweden)

    Guang Zhang

    2016-10-01

    Full Text Available Two light-emitting polyphenylene dendrimers with both hole and electron transporting moieties were synthesized and characterized. Both molecules exhibited pure blue emission solely from the pyrene core and efficient surface-to-core energy transfers when characterized in a nonpolar environment. In particular, the carbazole- and oxadiazole-functionalized dendrimer (D1 manifested a pure blue emission from the pyrene core without showing intramolecular charge transfer (ICT in environments with increasing polarity. On the other hand, the triphenylamine- and oxadiazole-functionalized one (D2 displayed notable ICT with dual emission from both the core and an ICT state in highly polar solvents. D1, in a three-layer organic light emitting diode (OLED by solution processing gave a pure blue emission with Commission Internationale de l’Éclairage 1931 CIE xy = (0.16, 0.12, a peak current efficiency of 0.21 cd/A and a peak luminance of 2700 cd/m2. This represents the first reported pure blue dendrimer emitter with bipolar charge transport and surface-to-core energy transfer in OLEDs.

  18. Low-energy light bulbs, computers, tablets and the blue light hazard.

    Science.gov (United States)

    O'Hagan, J B; Khazova, M; Price, L L A

    2016-02-01

    The introduction of low energy lighting and the widespread use of computer and mobile technologies have changed the exposure of human eyes to light. Occasional claims that the light sources with emissions containing blue light may cause eye damage raise concerns in the media. The aim of the study was to determine if it was appropriate to issue advice on the public health concerns. A number of sources were assessed and the exposure conditions were compared with international exposure limits, and the exposure likely to be received from staring at a blue sky. None of the sources assessed approached the exposure limits, even for extended viewing times.

  19. Adaptation to Blue Light in MarineSynechococcusRequires MpeU, an Enzyme with Similarity to Phycoerythrobilin Lyase Isomerases.

    Science.gov (United States)

    Mahmoud, Rania M; Sanfilippo, Joseph E; Nguyen, Adam A; Strnat, Johann A; Partensky, Frédéric; Garczarek, Laurence; Abo El Kassem, Nabil; Kehoe, David M; Schluchter, Wendy M

    2017-01-01

    Marine Synechococcus has successfully adapted to environments with different light colors, which likely contributes to this genus being the second most abundant group of microorganisms worldwide. Populations of Synechococcus that grow in deep, blue ocean waters contain large amounts of the blue-light absorbing chromophore phycourobilin (PUB) in their light harvesting complexes (phycobilisomes). Here, we show that all Synechococcus strains adapted to blue light possess a gene called mpeU . MpeU is structurally similar to phycobilin lyases, enzymes that ligate chromophores to phycobiliproteins. Interruption of mpeU caused a reduction in PUB content, impaired phycobilisome assembly and reduced growth rate more strongly in blue than green light. When mpeU was reintroduced in the mpeU mutant background, the mpeU- less phenotype was complemented in terms of PUB content and phycobilisome content. Fluorescence spectra of mpeU mutant cells and purified phycobilisomes revealed red-shifted phycoerythrin emission peaks, likely indicating a defect in chromophore ligation to phycoerythrin-I (PE-I) or phycoerythrin-II (PE-II). Our results suggest that MpeU is a lyase-isomerase that attaches a phycoerythrobilin to a PEI or PEII subunit and isomerizes it to PUB. MpeU is therefore an important determinant in adaptation of Synechococcus spp. to capture photons in blue light environments throughout the world's oceans.

  20. Blue-green phosphor for fluorescent lighting applications

    Science.gov (United States)

    Srivastava, Alok; Comanzo, Holly; Manivannan, Venkatesan; Setlur, Anant Achyut

    2005-03-15

    A fluorescent lamp including a phosphor layer including Sr.sub.4 Al.sub.14 O.sub.25 :Eu.sup.2+ (SAE) and at least one of each of a red, green and blue emitting phosphor. The phosphor layer can optionally include an additional, deep red phosphor and a yellow emitting phosphor. The resulting lamp will exhibit a white light having a color rendering index of 90 or higher with a correlated color temperature of from 2500 to 10000 Kelvin. The use of SAE in phosphor blends of lamps results in high CRI light sources with increased stability and acceptable lumen maintenance over, the course of the lamp life.

  1. Blue light for infectious diseases: Propionibacterium acnes, Helicobacter pylori, and beyond?

    Science.gov (United States)

    Dai, Tianhong; Gupta, Asheesh; Murray, Clinton K.; Vrahas, Mark S.; Tegos, George P.; Hamblin, Michael R.

    2012-01-01

    Blue light, particularly in the wavelength range of 405–470 nm, has attracted increasing attention due to its intrinsic antimicrobial effect without the addition of exogenous photosensitizers. In addition, it is commonly accepted that blue light is much less detrimental to mammalian cells than ultraviolet irradiation, which is another light-based antimicrobial approach being investigated. In this review, we discussed the blue light sensing systems in microbial cells, antimicrobial efficacy of blue light, the mechanism of antimicrobial effect of blue light, the effects of blue light on mammalian cells, and the effects of blue light on wound healing. It has been reported that blue light can regulate multi-cellular behavior involving cell-to-cell communication via blue light receptors in bacteria, and inhibit biofilm formation and subsequently potentiate light inactivation. At higher radiant exposures, blue light exhibits a broad-spectrum antimicrobial effect against both Gram-positive and Gram-negative bacteria. Blue light therapy is a clinically accepted approach for Propionibacterium acnes infections. Clinical trials have also been conducted to investigate the use of blue light for Helicobacter pylori stomach infections and have shown promising results. Studies on blue light inactivation of important wound pathogenic bacteria, including Staphylococcus aureus and Pseudomonas aeruginosa have also been reported. The mechanism of blue light inactivation of P. acnes, H. pylori, and some oral bacteria is the photo-excitation of intracellular porphyrins and the subsequent production of cytotoxic reactive oxygen species. Although it may be the case that the mechanism of blue light inactivation of wound pathogens (e.g., S. aureus, P. aeruginosa) is the same as that of P. acnes, this hypothesis has not been rigorously tested. Limited and discordant results have been reported regarding the effects of blue light on mammalian cells and wound healing. Under certain wavelengths

  2. Meridional gradients of light absorbing carbon over northern Europe

    International Nuclear Information System (INIS)

    Baumgardner, D; Kok, G; Kraemer, M; Weidle, F

    2008-01-01

    In situ measurements have been made in the upper troposphere of the properties of particles containing light absorbing carbon (LAC). These measurements, made in late November 2006 over northern Europe, show that the average LAC mass concentration varies between 1 and 5 ng m -3 over a latitude range 50 deg. to 70 deg. N, with maxima at 50 deg. and 66 deg. The relative fraction of all particles larger than 0.1 μm that contain LAC decreases at higher latitudes. The derived extinction coefficient, which also increases with latitude, reaches a maximum of 1.4 Mm -1 at 66 deg. The air mass histories associated with the LAC were evaluated with back trajectory analysis using wind field analysis from the European Center for Median-Range Weather Forecast (ECMWF). A positive correlation exists between the fraction of particles containing LAC and the maximum relative humidity (RH), minimum temperature and maximum number of hours of cloud experienced by the air mass in the 5-10 days prior to being sampled by the aircraft. Air masses arriving from lower altitudes and with trajectories over North America also had larger concentration fractions of LAC. The average LAC mass is in good agreement with previous measurements made over North America for the same latitude range, and the span of values fits best with model predictions of LAC distributions that assume that the LAC transported from surface sources is hydrophobic

  3. Do blue-light filtering intraocular lenses affect visual function?

    Science.gov (United States)

    Lavric, Alenka; Pompe, Manca Tekavcic

    2014-11-01

    To study different aspects of visual function, macular changes, and subjective differences between the eye with an ultraviolet (UV) and blue-light filtering intraocular lens (IOL) and the fellow eye with a UV-light filtering IOL. Thirty patients (60 eyes) with senile cataract had both cataracts extracted, and an IOL was implanted at least 2 years before clinical evaluation. In one eye, AcrySof SA60AT (a UV-light filtering IOL) was implanted, whereas in the contralateral eye, AcrySof IQ SN60WF (a blue-light filtering IOL) was implanted. Each patient underwent visual acuity testing, color vision testing (Ishihara and Farnsworth-Munsell 100-hue tests), and contrast sensitivity (CS) testing. The macula was evaluated with optical coherence tomography and with clinical examination. Patients were asked if they noted any difference between the implanted IOLs concerning visual impression. Subjective visual quality was evaluated using the National Eye Institute Visual Functioning Questionnaire. There was a borderline statistically significant difference in the mean best-corrected visual acuity (p = 0.05). As regards color vision, no significant changes in Ishihara and Farnsworth-Munsell 100-hue error scores were detected between both eyes (p = 0.48 and p = 0.59, respectively). Analysis of CS showed no significant difference between the groups at any spatial frequency. There were also no statistically significant differences in central macular thickness and total macular volume between the two IOL groups (p = 0.72 and p = 0.61, respectively). In both IOL groups, three eyes developed an epiretinal membrane, and six eyes developed early signs of age-related macular degeneration. This study showed no significant effects of a blue-light filtering IOL on visual acuity and no influence on color perception and CS. After more than 2 years, there were no significant differences in macular changes between the IOL groups. Clinical evidence of the effect of a blue-light filtering IOL on

  4. Damage of photoreceptor-derived cells in culture induced by light emitting diode-derived blue light

    OpenAIRE

    Kuse, Yoshiki; Ogawa, Kenjiro; Tsuruma, Kazuhiro; Shimazawa, Masamitsu; Hara, Hideaki

    2014-01-01

    Our eyes are increasingly exposed to light from the emitting diode (LED) light of video display terminals (VDT) which contain much blue light. VDTs are equipped with televisions, personal computers, and smart phones. The present study aims to clarify the mechanism underlying blue LED light-induced photoreceptor cell damage. Murine cone photoreceptor-derived cells (661 W) were exposed to blue, white, or green LED light (0.38 mW/cm2). In the present study, blue LED light increased reactive oxyg...

  5. Effects of blue light on the circadian system and eye physiology

    OpenAIRE

    Tosini, Gianluca; Ferguson, Ian; Tsubota, Kazuo

    2016-01-01

    Light-emitting diodes (LEDs) have been used to provide illumination in industrial and commercial environments. LEDs are also used in TVs, computers, smart phones, and tablets. Although the light emitted by most LEDs appears white, LEDs have peak emission in the blue light range (400?490 nm). The accumulating experimental evidence has indicated that exposure to blue light can affect many physiologic functions, and it can be used to treat circadian and sleep dysfunctions. However, blue light ca...

  6. Antimicrobial blue light inactivation of pathogenic microbes: State of the art.

    Science.gov (United States)

    Wang, Yucheng; Wang, Ying; Wang, Yuguang; Murray, Clinton K; Hamblin, Michael R; Hooper, David C; Dai, Tianhong

    2017-11-01

    As an innovative non-antibiotic approach, antimicrobial blue light in the spectrum of 400-470nm has demonstrated its intrinsic antimicrobial properties resulting from the presence of endogenous photosensitizing chromophores in pathogenic microbes and, subsequently, its promise as a counteracter of antibiotic resistance. Since we published our last review of antimicrobial blue light in 2012, there have been a substantial number of new studies reported in this area. Here we provide an updated overview of the findings from the new studies over the past 5 years, including the efficacy of antimicrobial blue light inactivation of different microbes, its mechanism of action, synergism of antimicrobial blue light with other angents, its effect on host cells and tissues, the potential development of resistance to antimicrobial blue light by microbes, and a novel interstitial delivery approach of antimicrobial blue light. The potential new applications of antimicrobial blue light are also discussed. Copyright © 2017 Elsevier Ltd. All rights reserved.

  7. Effects of blue light on the circadian system and eye physiology.

    Science.gov (United States)

    Tosini, Gianluca; Ferguson, Ian; Tsubota, Kazuo

    2016-01-01

    Light-emitting diodes (LEDs) have been used to provide illumination in industrial and commercial environments. LEDs are also used in TVs, computers, smart phones, and tablets. Although the light emitted by most LEDs appears white, LEDs have peak emission in the blue light range (400-490 nm). The accumulating experimental evidence has indicated that exposure to blue light can affect many physiologic functions, and it can be used to treat circadian and sleep dysfunctions. However, blue light can also induce photoreceptor damage. Thus, it is important to consider the spectral output of LED-based light sources to minimize the danger that may be associated with blue light exposure. In this review, we summarize the current knowledge of the effects of blue light on the regulation of physiologic functions and the possible effects of blue light exposure on ocular health.

  8. Effects of blue light on the circadian system and eye physiology

    Science.gov (United States)

    Ferguson, Ian; Tsubota, Kazuo

    2016-01-01

    Light-emitting diodes (LEDs) have been used to provide illumination in industrial and commercial environments. LEDs are also used in TVs, computers, smart phones, and tablets. Although the light emitted by most LEDs appears white, LEDs have peak emission in the blue light range (400–490 nm). The accumulating experimental evidence has indicated that exposure to blue light can affect many physiologic functions, and it can be used to treat circadian and sleep dysfunctions. However, blue light can also induce photoreceptor damage. Thus, it is important to consider the spectral output of LED-based light sources to minimize the danger that may be associated with blue light exposure. In this review, we summarize the current knowledge of the effects of blue light on the regulation of physiologic functions and the possible effects of blue light exposure on ocular health. PMID:26900325

  9. Structure Optimization of 21,23-Core-Modified Porphyrins Absorbing Long-Wavelength Light as Potential Photosensitizers Against Breast Cancer Cells

    Science.gov (United States)

    2008-04-01

    porphyrin and induction of apoptosis. Journal of Photochemistry and Photobiology B: Biology 2006, 85, 155-162. 4. You, Y .; Daniels, T. S.; Dominiak, P. M...Cells were loaded with 0.4% trypan blue on a hematocytometer slide at the ratio 1:1 (v/v) and analyzed by light microscopy. The percentage of dead...Modified Porphyrins Absorbing Long- Wavelength Light as Potential Photosensitizers Against Breast Cancer Cells PRINCIPAL INVESTIGATOR: Michael R

  10. Blue light emitting diodes for optical stimulation of quartz in retrospective dosimetry and dating

    DEFF Research Database (Denmark)

    Bøtter-Jensen, L.; Duller, G.A.T.; Murray, A.S.

    1999-01-01

    Recently developed blue light emitting diodes (LEDs) for the optical stimulation of quartz for use in routine optically stimulated luminescence (OSL) dating and retrospective dosimetry have been tested. For similar power densities, it was found that the higher energy light provided by the blue LEDs...... (470 nm) gives order of magnitude greater rate of stimulation in quartz than that from conventional blue-green light filtered from a halogen lamp. A practical blue LED OSL configuration is described. From comparisons of OSL decay curves produced by green and blue light sources, and by examination...... of the dependence of the blue LED OSL on preheat temperature, it is deduced that there is no evidence that the blue LEDs stimulate deep traps in a different manner from broadband filtered light. It is concluded that blue LEDs offer a practical alternative to existing stimulation sources. They have the significant...

  11. Blue light-induced immunosuppression in Bactrocera dorsalis adults, as a carryover effect of larval exposure.

    Science.gov (United States)

    Tariq, K; Noor, M; Hori, M; Ali, A; Hussain, A; Peng, W; Chang, C-J; Zhang, H

    2017-12-01

    Detrimental effects of ultraviolet (UV) light on living organisms are well understood, little is known about the effects of blue light irradiation. Although a recent study revealed that blue light caused more harmful effects on insects than UV light and blue light irradiation killed insect pests of various orders including Diptera, the effects of blue light on physiology of insects are still largely unknown. Here we studied the effects of blue light irradiation on cuticular melanin in larval and the immune response in adult stage of Bactrocera dorsalis. We also evaluated the effects of blue light exposure in larval stage on various age and mass at metamorphosis and the mediatory role of cuticular melanin in carryover effects of larval stressors across metamorphosis. We found that larvae exposed to blue light decreased melanin contents in their exoskeleton with smaller mass and delayed metamorphosis than insects reared without blue light exposure. Across metamorphosis, lower melanotic encapsulation response and higher susceptibility to Beauveria bassiana was detected in adults that had been exposed to blue light at their larval stage, thereby constituting the first evidence that blue light impaired adult immune function in B. dorsalis as a carryover effect of larval exposure.

  12. Blue light dose–responses of leaf photosynthesis, morphology, and chemical composition of Cucumis sativus grown under different combinations of red and blue light

    NARCIS (Netherlands)

    Hogewoning, S.W.; Trouwborst, G.; Maljaars, H.; Poorter, H.; Ieperen, van W.; Harbinson, J.

    2010-01-01

    The blue part of the light spectrum has been associated with leaf characteristics which also develop under high irradiances. In this study blue light dose–response curves were made for the photosynthetic properties and related developmental characteristics of cucumber leaves that were grown at an

  13. Influence of Light Emitting Diode-Derived Blue Light Overexposure on Mouse Ocular Surface.

    Science.gov (United States)

    Lee, Hyo Seok; Cui, Lian; Li, Ying; Choi, Ji Suk; Choi, Joo-Hee; Li, Zhengri; Kim, Ga Eon; Choi, Won; Yoon, Kyung Chul

    2016-01-01

    To investigate the influence of overexposure to light emitting diode (LED)-derived light with various wavelengths on mouse ocular surface. LEDs with various wavelengths were used to irradiate C57BL/6 mice at an energy dose of 50 J/cm2, twice a day, for 10 consecutive days. The red, green, and blue groups represented wavelengths of 630 nm, 525 nm, and 410 nm, respectively. The untouched group (UT) was not exposed to LED light and served as the untreated control. Tear volume, tear film break-up time (TBUT), and corneal fluorescein staining scores were measured on days 1, 3, 5, 7, and 10. Levels of interferon (IFN)-γ, interleukin (IL)-1β, IL-6, and tumor necrosis factor (TNF)-α were measured in the cornea and conjunctiva using a multiplex immunobead assay at day 10. Levels of malondialdehyde (MDA) were measured with an enzyme-linked immunosorbent assay. Flow cytometry, 2'7'-dichlorofluorescein diacetate (DCF-DA) assay, histologic analysis, immunohistochemistry with 4-hydroxynonenal, and terminal deoxynucleotidyl transferase-mediated dUTP-nick end labeling (TUNEL) staining were also performed. TBUT of the blue group showed significant decreases at days 7 and 10, compared with the UT and red groups. Corneal fluorescein staining scores significantly increased in the blue group when compared with UT, red, and green groups at days 5, 7, and 10. A significant increase in the corneal levels of IL-1β and IL-6 was observed in the blue group, compared with the other groups. The blue group showed significantly increased reactive oxygen species production in the DCF-DA assay and increased inflammatory T cells in the flow cytometry. A significantly increased TUNEL positive cells was identified in the blue group. Overexposure to blue light with short wavelengths can induce oxidative damage and apoptosis to the cornea, which may manifest as increased ocular surface inflammation and resultant dry eye.

  14. Suppressed speckle contrast of blue light emission out of white lamp with phosphors excited by blue laser diodes for high-brightness lighting applications

    Science.gov (United States)

    Kinoshita, Junichi; Ikeda, Yoshihisa; Takeda, Yuji; Ueno, Misaki; Kawasaki, Yoji; Matsuba, Yoshiaki; Heike, Atsushi

    2012-11-01

    The speckle contrast of blue light emission out of high-brightness white lamps using phosphors excited by InGaN/GaN blue laser diodes is evaluated as a measure of coherence. As a result, speckle contrast of as low as 1.7%, the same level as a blue light emitting diode, is obtained. This implies that the original blue laser light can be converted into incoherent light through lamp structures without any dynamic mechanisms. This unique speckle-free performance is considered to be realized by multiple scattering inside the lamp structure, the multi-longitudinal mode operation of the blue laser diodes, and the use of multiple laser diodes. Such almost-incoherent white lamps can be applied for general lighting without any nuisance of speckle noise and should be categorized as lamps rather than lasers in terms of laser safety regulation.

  15. Effects and Mechanism of Blue Light on Monascus in Liquid Fermentation

    Directory of Open Access Journals (Sweden)

    Xiaowei Zhang

    2017-03-01

    Full Text Available The effect of light on Monascus and the underlying mechanism have received a great deal of interest for the industrial application of Monascus pigments. In this study, we have examined the effects of blue light on the culture morphology, mycelium growth, pigments, and citrinin yield of Monascus in liquid-state and oscillation fermentation, and explored the mechanism at a physiological level. It was found that blue light affected the colony morphology, the composition (chitin content, and permeability of the Monascus mycelium cell wall in static liquid culture, which indicates blue light benefits pigments secreting from aerial mycelium to culture medium. In liquid oscillation fermentation, the yields of Monascus pigments in fermentation broth (darkness 1741 U/g, blue light 2206 U/g and mycelium (darkness 2442 U/g, blue light 1900 U/g cultured under blue light and darkness are different. The total pigments produced per gram of Monascus mycelium under blue light was also higher (4663 U/g than that in darkness (4352 U/g. However, the production of citrinin (88 μg/g under blue light was evidently lower than that in darkness (150 μg/g. According to the degradation of citrinin caused by blue light and hydrogen peroxide, it can be concluded that blue light could degrade citrinin and inhibit the catalase activity of Monascus mycelium, subsequently suppressing the decomposition of hydrogen peroxide, which is the active species that degrades citrinin.

  16. Effects and Mechanism of Blue Light on Monascus in Liquid Fermentation.

    Science.gov (United States)

    Zhang, Xiaowei; Liu, Wenqing; Chen, Xiying; Cai, Junhui; Wang, Changlu; He, Weiwei

    2017-03-01

    The effect of light on Monascus and the underlying mechanism have received a great deal of interest for the industrial application of Monascus pigments. In this study, we have examined the effects of blue light on the culture morphology, mycelium growth, pigments, and citrinin yield of Monascus in liquid-state and oscillation fermentation, and explored the mechanism at a physiological level. It was found that blue light affected the colony morphology, the composition (chitin content), and permeability of the Monascus mycelium cell wall in static liquid culture, which indicates blue light benefits pigments secreting from aerial mycelium to culture medium. In liquid oscillation fermentation, the yields of Monascus pigments in fermentation broth (darkness 1741 U/g, blue light 2206 U/g) and mycelium (darkness 2442 U/g, blue light 1900 U/g) cultured under blue light and darkness are different. The total pigments produced per gram of Monascus mycelium under blue light was also higher (4663 U/g) than that in darkness (4352 U/g). However, the production of citrinin (88 μg/g) under blue light was evidently lower than that in darkness (150 μg/g). According to the degradation of citrinin caused by blue light and hydrogen peroxide, it can be concluded that blue light could degrade citrinin and inhibit the catalase activity of Monascus mycelium, subsequently suppressing the decomposition of hydrogen peroxide, which is the active species that degrades citrinin.

  17. Blue light for infectious diseases: Propionibacterium acnes, Helicobacter pylori, and beyond?

    OpenAIRE

    Dai, Tianhong; Gupta, Asheesh; Murray, Clinton K.; Vrahas, Mark S.; Tegos, George P.; Hamblin, Michael R.

    2012-01-01

    Blue light, particularly in the wavelength range of 405–470 nm, has attracted increasing attention due to its intrinsic antimicrobial effect without the addition of exogenous photosensitizers. In addition, it is commonly accepted that blue light is much less detrimental to mammalian cells than ultraviolet irradiation, which is another light-based antimicrobial approach being investigated. In this review, we discussed the blue light sensing systems in microbial cells, antimicrobial efficacy of...

  18. Broad-spectrum light versus blue light for phototherapy in neonatal hyperbilirubinemia: a randomized controlled trial.

    Science.gov (United States)

    Pratesi, Simone; Di Fabio, Sandra; Bresci, Cecilia; Di Natale, Cecilia; Bar, Shahar; Dani, Carlo

    2015-07-01

    Phototherapy is standard care for treatment of neonatal hyperbilirubinemia. Our aim was to compare the effectiveness of broad-spectrum light (BSL) to that of blue light emitting diodes (LED) phototherapy for the treatment of jaundiced late preterm and term infants. Infants with gestational age from 35(+0) to 41(+6) weeks of gestation and nonhemolytic hyperbilirubinemia were randomized to treatment with BSL phototherapy or blue LED phototherapy. A total of 20 infants were included in the blue LED phototherapy group and 20 in the BSL phototherapy group. The duration of phototherapy was lower in the BSL than in the blue LED phototherapy group (15.8 ± 4.9 vs. 20.6 ± 6.0 hours; p = 0.009), and infants in the former group had a lower probability (p = 0.015) of remaining in phototherapy than infants in the latter. We concluded that BSL phototherapy is more effective than blue LED phototherapy for the treatment of hyperbilirubinemia in late preterm and term infants. Our data suggest that these results are not due to the different irradiance of the two phototherapy systems, but probably depend on their different peak light emissions. Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.

  19. Unequal allocation of excitation energy between photosystem II and I reduces cyanolichen photosynthesis in blue light.

    Science.gov (United States)

    Solhaug, Knut Asbjørn; Xie, Li; Gauslaa, Yngvar

    2014-08-01

    Photosynthesis was compared in two cyanobacterial lichens (Lobaria hallii and Peltigera praetextata) and two green algal lichens (Lobaria pulmonaria and Peltigera leucophlebia) exposed to red, green or blue light. Cyanolichens had substantially lower photosynthetic CO(2) uptake and O(2) evolution than the green algal lichens in blue light, but slightly higher photosynthesis in red and green light. The effective quantum yield of photosystem (PS) II (Φ(PSII)) decreased with increasing red and green light for all species, but in blue light this response occurred in green algal lichens only. Cyanolichen Φ(PSII) increased with increasing blue light at low irradiances, but decreased at stronger exposures. However, after adding red light the efficiency of blue light for photosynthetic O(2) evolution increased by 2.4 times. Because phycobilisomes associated with PSII have a low blue light absorption, our results are consistent with blue light absorption mainly by Chl in PSI. Thereby, unequal allocation of excitation energy between PSII and PSI results in low cyanolichen photosynthesis under blue light. This is new knowledge in the science of lichenology with important implications for e.g. the reliability of using Chl fluorometers with blue light for cyanolichens. © The Author 2014. Published by Oxford University Press on behalf of Japanese Society of Plant Physiologists. All rights reserved. For permissions, please email: journals.permissions@oup.com.

  20. Blue Light Phototherapy Kills Methycillin Resistant Staphylococcus Aureus (MRSA)

    Science.gov (United States)

    Enwemeka, Chukuka S.; Williams, Debora; Enwemeka, Sombiri K.; Hollosi, Steve; Yens, David

    2010-05-01

    Background: Methycillin resistant staphylococcus aureus (MRSA) bacteria continue to defy most available antibiotics. As a result infections with MRSA remain a growing public health concern. As a paradigm shift and a significant departure from the on-going trend to develop stronger drug-based therapies, we studied the effect of 405 nm and 470 nm wavelengths of blue light on two strains of MRSA—US-300 strain of CA-MRSA and the IS853 strain of HA-MRSA—in vitro. Methods: We cultured and plated each strain, following which bacteria colonies were irradiated with 0, 1, 3, 5, 7, 9, 11, 13, 15, 17, 19, 25, 30, 35, 40, 45, 50, 55, or 60 Jcm-2 energy densities—just once. Specimens were incubated at 35° C for 24 h. Then, digital images obtained were quantified to obtain colony counts and the aggregate area occupied by bacteria colonies. Results: Each wavelength produced a statistically significant dose-dependent reduction in both the number and the aggregate area of colonies formed by each bacteria strain (Peffect was non-linear as increases of energy densities between 1.0 and 15 J cm-2 resulted in more bacteria death than similar increases between 15 J cm-2 and 60 J cm-2. Conclusion: At low doses, blue light photo-destroys HA-MRSA and CA-MRSA in vitro; raising the prospect that phototherapy may be an effective clinical tool in the on-going effort to stem MRSA infections.

  1. Antimicrobial effect of blue light using Porphyromonas gingivalis pigment.

    Science.gov (United States)

    Yoshida, Ayaka; Sasaki, Haruka; Toyama, Toshizo; Araki, Mitsunori; Fujioka, Jun; Tsukiyama, Koichi; Hamada, Nobushiro; Yoshino, Fumihiko

    2017-07-12

    The development of antibiotics cannot keep up with the speed of resistance acquired by microorganisms. Recently, the development of antimicrobial photodynamic therapy (aPDT) has been a necessary antimicrobial strategy against antibiotic resistance. Among the wide variety of bacteria found in the oral flora, Porphyromonas gingivalis (P. gingivalis) is one of the etiological agents of periodontal disease. aPDT has been studied for periodontal disease, but has risks of cytotoxicity to normal stained tissue. In this study, we performed aPDT using protoporphyrin IX (PpIX), an intracellular pigment of P. gingivalis, without an external photosensitizer. We confirmed singlet oxygen generation by PpIX in a blue-light irradiation intensity-dependent manner. We discovered that blue-light irradiation on P. gingivalis is potentially bactericidal. The sterilization mechanism seems to be oxidative DNA damage in bacterial cells. Although it is said that no resistant bacteria will emerge using aPDT, the conventional method relies on an added photosensitizer dye. PpIX in P. gingivalis is used in energy production, so aPDT applied to PpIX of P. gingivalis should limit the appearance of resistant bacteria. This approach not only has potential as an effective treatment for new periodontal diseases, but also offers potential antibacterial treatment for multiple drug resistant bacteria.

  2. High efficiency blue phosphorescent organic light-emitting diodes without electron transport layer

    Energy Technology Data Exchange (ETDEWEB)

    Jeon, Soon Ok [Department of Polymer Science and Engineering, Dankook University, Jukjeon-dong, Suji-gu, Yongin-si, Gyeonggi-do 448-701 (Korea, Republic of); Lee, Jun Yeob, E-mail: leej17@dankook.ac.kr [Department of Polymer Science and Engineering, Dankook University, Jukjeon-dong, Suji-gu, Yongin-si, Gyeonggi-do 448-701 (Korea, Republic of)

    2011-08-15

    High efficiency blue phosphorescent organic light-emitting diodes were fabricated without an electron transport layer using a spirobifluorene based blue triplet host material. The simple blue PHOLEDs without the electron transport layer showed a high external quantum efficiency and current efficiency of 16.1% and 30.2 cd/A, respectively. The high device performances of the electron transport layer free blue PHOLEDs were comparable to those of blue PHOLEDs with the electron transport layer. - Highlights: > Simple device structure without electron transport layer. > High efficiency blue phosphorescent organic light-emitting diode. > Spirobifluorene based high triplet energy host material.

  3. Plant responses to UV and blue light: biochemical and genetic approaches

    International Nuclear Information System (INIS)

    Jenkins, G.I.; Christie, J.M.; Fuglevand, G.; Long, J.C.; Jackson, J.A.

    1995-01-01

    UV and blue light control many aspects of plant growth and development. It is evident that several different photoreceptors mediate responses to UV and blue light, and there are reports of the functional and biochemical characterisation of a putative photoreceptor for phototropism and of the functional and molecular characterisation of the CRY1 photoreceptor, encoded by the Arabidopsis HY4 gene. The CRY1 photoreceptor mediates extension growth and gene expression responses to UV-A/blue light presumably through different or branching signal transduction pathways. Progress has been made in cell physiological and biochemical studies of UV/blue light signal transduction, but much remains to be done to relate candidate UV/blue signal transduction events to particular photoreceptors and responses. The application of a genetic approach in Arabidopsis has been responsible for many advances in understanding UV/blue responses, but further UV-B, UV-A and blue light response mutants need to be isolated. (author)

  4. Investigation of the molecular mechanism of the blue-light-specific excitation energy quenching in the plant antenna complex LHCII.

    Science.gov (United States)

    Gruszecki, Wieslaw I; Zubik, Monika; Luchowski, Rafal; Grudzinski, Wojciech; Gospodarek, Malgorzata; Szurkowski, Janusz; Gryczynski, Zygmunt; Gryczynski, Ignacy

    2011-03-15

    Excitation of the major photosynthetic antenna complex of plants, LHCII, with blue light (470nm) provides an advantage to plants, as it gives rise to chlorophyll a fluorescence lifetimes shorter than with excitation with red light (635nm). This difference is particularly pronounced in fluorescence emission wavelengths longer than 715nm. Illumination of LHCII preparation with blue light additionally induces fluorescence quenching, which develops on a minute timescale. This effect is much less efficient when induced by red light, despite the equalized energy absorbed in both the spectral regions. Simultaneous analysis of the fluorescence and photoacoustic signals in LHCII demonstrated that the light-driven fluorescence quenching is not associated with an increase in heat emission. Instead, a reversible light-induced conformational transformation of the protein takes place, as demonstrated by the FTIR technique. These findings are discussed in terms of the blue-light-specific excitation energy quenching in LHCII, which may have photoprotective applications. Copyright © 2010 Elsevier GmbH. All rights reserved.

  5. Effects of blue pulsed light on human physiological functions and subjective evaluation

    Directory of Open Access Journals (Sweden)

    Katsuura Tetsuo

    2012-09-01

    Full Text Available Abstract Background It has been assumed that light with a higher irradiance of pulsed blue light has a much greater influence than that of light with a lower irradiance of steady blue light, although they have the same multiplication value of irradiance and duration. We examined the non-visual physiological effects of blue pulsed light, and determined whether it is sensed visually as being blue. Findings Seven young male volunteers participated in the study. We placed a circular screen (diameter 500 mm in front of the participants and irradiated it using blue and/or white light-emitting diodes (LEDs, and we used halogen lamps as a standard illuminant. We applied three steady light conditions of white LED (F0, blue LED + white LED (F10, and blue LED (F100, and a blue pulsed light condition of a 100-μs pulse width with a 10% duty ratio (P10. The irradiance of all four conditions at the participant's eye level was almost the same, at around 12 μW/cm2. We measured their pupil diameter, recorded electroencephalogram readings and Kwansei Gakuin Sleepiness Scale score, and collected subjective evaluations. The subjective bluish score under the F100 condition was significantly higher than those under other conditions. Even under the P10 condition with a 10% duty ratio of blue pulsed light and the F10 condition, the participant did not perceive the light as bluish. Pupillary light response under the P10 pulsed light condition was significantly greater than under the F10 condition, even though the two conditions had equal blue light components. Conclusions The pupil constricted under the blue pulsed light condition, indicating a non-visual effect of the lighting, even though the participants did not perceive the light as bluish.

  6. Blue Light Modulates Murine Microglial Gene Expression in the Absence of Optogenetic Protein Expression.

    Science.gov (United States)

    Cheng, Kevin P; Kiernan, Elizabeth A; Eliceiri, Kevin W; Williams, Justin C; Watters, Jyoti J

    2016-02-17

    Neural optogenetic applications over the past decade have steadily increased; however the effects of commonly used blue light paradigms on surrounding, non-optogenetic protein-expressing CNS cells are rarely considered, despite their simultaneous exposure. Here we report that blue light (450 nm) repetitively delivered in both long-duration boluses and rapid optogenetic bursts gene-specifically altered basal expression of inflammatory and neurotrophic genes in immortalized and primary murine wild type microglial cultures. In addition, blue light reduced pro-inflammatory gene expression in microglia activated with lipopolysaccharide. These results demonstrate previously unreported, off-target effects of blue light in cells not expressing optogenetic constructs. The unexpected gene modulatory effects of blue light on wild type CNS resident immune cells have novel and important implications for the neuro-optogenetic field. Further studies are needed to elucidate the molecular mechanisms and potential therapeutic utility of blue light modulation of the wild type CNS.

  7. Blue Light Modulates Murine Microglial Gene Expression in the Absence of Optogenetic Protein Expression

    Science.gov (United States)

    Cheng, Kevin P.; Kiernan, Elizabeth A.; Eliceiri, Kevin W.; Williams, Justin C.; Watters, Jyoti J.

    2016-01-01

    Neural optogenetic applications over the past decade have steadily increased; however the effects of commonly used blue light paradigms on surrounding, non-optogenetic protein-expressing CNS cells are rarely considered, despite their simultaneous exposure. Here we report that blue light (450 nm) repetitively delivered in both long-duration boluses and rapid optogenetic bursts gene-specifically altered basal expression of inflammatory and neurotrophic genes in immortalized and primary murine wild type microglial cultures. In addition, blue light reduced pro-inflammatory gene expression in microglia activated with lipopolysaccharide. These results demonstrate previously unreported, off-target effects of blue light in cells not expressing optogenetic constructs. The unexpected gene modulatory effects of blue light on wild type CNS resident immune cells have novel and important implications for the neuro-optogenetic field. Further studies are needed to elucidate the molecular mechanisms and potential therapeutic utility of blue light modulation of the wild type CNS. PMID:26883795

  8. Responses of supplemental blue light on flowering and stem extension growth of cut chrysanthemum

    NARCIS (Netherlands)

    Jeong, S.W.; Hogewoning, S.W.; Ieperen, van W.

    2014-01-01

    To determine the effects of blue (B) spectrum supplemental lighting on flower bud formation and stem elongation growth of cut chrysanthemum, plants of ‘Zembla’ cultivar were grown for 42 days under 4 different light treatments. Treatments comprised: RB (11 h of mixed red and blue [RB] light), RB + B

  9. The Phototoxicity of ’Blue Light’ on the Functional Properties of the Retinal Pigment Epithelium

    Science.gov (United States)

    1990-10-15

    radiation did not affect any of the transport systems studied. Ascorbate, morin or vitamin E did not ameliorate the effect of blue light on transport...whereas melatonin did provide protection by forming an effective light filter. The combination of ethanol and exposure to blue light may constitute a

  10. UV-A/blue-light responses in algae

    Energy Technology Data Exchange (ETDEWEB)

    Senger, H.; Hermsmeier, D. [Philipps-Universitaet Marburg (Germany)

    1994-12-31

    All life on earth depends on light. A variety of photoreceptors capture the light for a wide range of reactions. Photosynthetic organisms absorb the light necessary for energy transformation and charge separation facilitating photosynthesis. In addition to the bulk pigments there are a great diversity of photoreceptors present in minute concentrations that control development, metabolism and orientation of plants and microorganisms. Based on its spectral absorbance, the well-studied phytochrome system acts in the RL region as well as in the UV-A/BL region where the above mentioned reactions are mediated by a variety of photoreceptors whose natures are largely unknown. Phyllogenetically the UV-A/BL photoreceptors seem to be more ancient pigments that eventually were replaced by the phytochrome system. However, there are many reports that suggest a coaction between the UV-A/BL receptors and the phytochrome system. In several cases the UV-A/BL activation is the prerequisite for the phytochrome reaction. Historically it was the German botanist Julius Sachs who first discovered in 1864 that phototropism in plants was due to BL reactions. It took over 70 years until Bunning (1937) and Galston and Baker (1949) rediscovered the BL response. Since then, an ever-increasing attention has been paid to this effect. Two international conferences in 1979 and 1983 have been entirely dedicated to the BL phenomenon. In this contribution, the general aspect of UV-A/BL responses and especially the responsiveness of algae will be covered. There are numerous review articles covering the various aspects of UV-A/BL action and the photoreceptors involved.

  11. [Artificial lighting and blue light in the operating room: what risks for the surgeon?].

    Science.gov (United States)

    Lembo, M; Cannatà, V; Militello, A; Ritrovato, M; Zaffina, S; Derrico, P; Borra, MassimoM

    2015-09-09

    Lighting in operating rooms must ensure conditions of visual comfort, wellbeing and safety when procedures are being carried out, so as to preserve  the health of both workers and patients. In this study we attempted to develop a methodology for specifically assessing the risk for surgeons of exposure to blue light, simulating the surgeon's real working conditions. Visual comfort was also assessed by measuring maintained illuminance (Em) and the luminance levels in the visual task area within the operating field. Blue light exposure was measured by an OCEAN OPTICS-QE65000 spectroradiometer and a LSI-Lastem model Z-Lux radiometer, while for lighting measurements, a videophotometer and luxmeter were used. Results show that the surgeons were exposed to blue light values lower than the limit of effective radiance LB= 100 W m-2 sr-1 foreseen by European Directive 2006/25/EC. For visual comfort, significant differences in illumination were observed between surrounding areas and the visual task areas, with very high luminance values measured in most of the observation points. In this case the measured values confirm that the workers were daily exposed to unsuitable luminance contrasts that can cause eyestrain. Given such results and considering the task analysis, we proposed to extend health surveillance to workers performing activities such as precision surgery for prolonged periods.

  12. Blue light irradiation-induced oxidative stress in vivo via ROS generation in rat gingival tissue.

    Science.gov (United States)

    Yoshida, Ayaka; Shiotsu-Ogura, Yukako; Wada-Takahashi, Satoko; Takahashi, Shun-suke; Toyama, Toshizo; Yoshino, Fumihiko

    2015-10-01

    It has been reported that oxidative stress with reactive oxygen species (ROS) generation is induced by blue light irradiation to a living body. Only limited research has been reported in dental field on the dangers of blue light, mostly focusing on cytotoxicity associated with heat injury of dental pulp. We thus performed an in vivo study on oral tissue exposed to blue light. ROS generated upon blue light irradiation of flavin adenine dinucleotide were measured by electron spin resonance spectroscopy. After blue light irradiation, the palatal gingiva of Wistar rats were isolated. Collected samples were subjected to biochemical analysis of lipid peroxidation and glutathione. Singlet oxygen was generated by blue light irradiation, but was significantly quenched in an N-acetyl-L-cysteine (NAC) concentration-dependent manner. Blue light significantly accelerated oxidative stress and increased the oxidized glutathione levels in gingival tissue. These effects were also inhibited by NAC pre-administration. The results suggest that blue light irradiation at clinical levels of tooth bleaching treatment may enhance lipid peroxidation by the induction of oxidative stress and the consumption of a significant amount of intracellular glutathione. In addition, NAC might be an effective supplement for the protection of oral tissues against blue light irradiation-induced oxidative damage. Copyright © 2015 Elsevier B.V. All rights reserved.

  13. Tolerability of Repeat Use of Blue Light Cystoscopy with Hexaminolevulinate for Patients with Urothelial Cell Carcinoma.

    Science.gov (United States)

    Lane, Giulia I; Downs, Tracy M; Soubra, Ayman; Rao, Amrita; Hemsley, Lauren; Laylan, Christopher; Shi, Fangfang; Konety, Badrinath

    2017-03-01

    Hexaminolevulinate hydrochloride with blue light cystoscopy is approved by the U.S. Food and Drug Administration as an adjunct to white light cystoscopy for the detection of urothelial cell carcinoma. In this study we examined the tolerability of the repeat use of white light cystoscopy with blue light cystoscopy. We retrospectively reviewed the records of all patients who underwent white light cystoscopy with blue light cystoscopy using hexaminolevulinate hydrochloride during a 34-month period at 2 institutions. We compared the incidence of adverse events after initial and subsequent procedures. We grouped, graded and assigned the degree of attribution for all adverse events. A total of 180 patients underwent 269 white light cystoscopy with blue light cystoscopy procedures. Of those 180 patients 118 (65%) underwent white light cystoscopy with blue light cystoscopy only 1 time. The other 62 (35%) patients underwent white light cystoscopy with blue light cystoscopy 2 or more times, including 43 (24%) 2 times and 19 (10%) 3 or more times. We noted 89 adverse events out of 269 procedures (33%), of which 66 (74%) occurred after the first white light cystoscopy with blue light cystoscopy; 14 (16%) after the second time and 9 (10%) after the third time or more. We found no statistically significant difference in adverse events between those patients undergoing 1 vs 2 or more white light cystoscopy with blue light cystoscopy procedures (p=0.134). We observed 1 grade 3 adverse event and no grade 4 or 5 adverse events. None of the adverse events were classified as probably or definitely related to hexaminolevulinate hydrochloride. In this retrospective study we found no statistically significant difference in the frequency or the grade of adverse events between first and repeat use of white light cystoscopy with blue light cystoscopy using hexaminolevulinate hydrochloride. Copyright © 2017 American Urological Association Education and Research, Inc. Published by Elsevier

  14. The Involvement of the Oxidative Stress in Murine Blue LED Light-Induced Retinal Damage Model.

    Science.gov (United States)

    Nakamura, Maho; Kuse, Yoshiki; Tsuruma, Kazuhiro; Shimazawa, Masamitsu; Hara, Hideaki

    2017-01-01

    The aim of study was to establish a mouse model of blue light emitting diode (LED) light-induced retinal damage and to evaluate the effects of the antioxidant N-acetylcysteine (NAC). Mice were exposed to 400 or 800 lx blue LED light for 2 h, and were evaluated for retinal damage 5 d later by electroretinogram amplitude and outer nuclear layer (ONL) thickness. Additionally, we investigated the effect of blue LED light exposure on shorts-wave-sensitive opsin (S-opsin), and rhodopsin expression by immunohistochemistry. Blue LED light induced light intensity dependent retinal damage and led to collapse of S-opsin and altered rhodopsin localization from inner and outer segments to ONL. Conversely, NAC administered at 100 or 250 mg/kg intraperitoneally twice a day, before dark adaptation and before light exposure. NAC protected the blue LED light-induced retinal damage in a dose-dependent manner. Further, blue LED light-induced decreasing of S-opsin levels and altered rhodopsin localization, which were suppressed by NAC. We established a mouse model of blue LED light-induced retinal damage and these findings indicated that oxidative stress was partially involved in blue LED light-induced retinal damage.

  15. Blue fluorescent organic light emitting diodes with multilayered graphene anode

    International Nuclear Information System (INIS)

    Hwang, Joohyun; Choi, Hong Kyw; Moon, Jaehyun; Shin, Jin-Wook; Joo, Chul Woong; Han, Jun-Han; Cho, Doo-Hee; Huh, Jin Woo; Choi, Sung-Yool; Lee, Jeong-Ik; Chu, Hye Yong

    2012-01-01

    As an innovative anode for organic light emitting devices (OLEDs), we have investigated graphene films. Graphene has importance due to its huge potential in flexible OLED applications. In this work, graphene films have been catalytically grown and transferred to the glass substrate for OLED fabrications. We have successfully fabricated 2 mm × 2 mm device area blue fluorescent OLEDs with graphene anodes which showed 2.1% of external quantum efficiency at 1000 cd/m 2 . This is the highest value reported among fluorescent OLEDs using graphene anodes. Oxygen plasma treatment on graphene has been found to improve hole injections in low voltage regime, which has been interpreted as oxygen plasma induced work function modification. However, plasma treatment also increases the sheet resistance of graphene, limiting the maximum luminance. In summary, our works demonstrate the practical possibility of graphene as an anode material for OLEDs and suggest a processing route which can be applied to various graphene related devices.

  16. Non-aqueous capillary electrophoresis with red light emitting diode absorbance detection for the analysis of basic dyes.

    Science.gov (United States)

    Fakhari, Ali Reza; Breadmore, Michael C; Macka, Miroslav; Haddad, Paul R

    2006-11-24

    Non-aqueous capillary electrophoresis was evaluated for the separation of five hydrophobic basic blue dyes for application in forensic dye analysis. The use of a red light emitting diode as a high intensity, low-noise light source provided sensitive detection of the blue dyes while also allowing the evaluation of solvents that absorb strongly in the UV region. Excellent peak shapes and separation selectivity were obtained in methanol, ethanol, acetonitrile and dimethylsulfoxide, however water, tetrahydrofuran, dimethylformamide and acetone were unsuitable as solvents due to poor peak shapes and a lack of sensitivity, most likely due to adsorption onto the capillary wall. Due to the known compatibility of methanol with capillary electrophoresis-mass spectrometry, this solvent was examined further with the relative acidity/basicity of the electrolyte being optimised with an artificial neural network. The optimised method was examined for the separation of ink samples from 6 fibre tip and 2 ball point blue or black pens and showed that a unique migration time for the main dye component in seven of the eight pens could be obtained.

  17. Close correspondence between the action spectra for the blue light responses of the guard cell and coleoptile chloroplasts, and the spectra for blue light-dependent stomatal opening and coleoptile phototropism.

    OpenAIRE

    Quiñones, M A; Lu, Z; Zeiger, E

    1996-01-01

    Fluorescence spectroscopy was used to characterize blue light responses from chloroplasts of adaxial guard cells from Pima cotton (Gossypium barbadense) and coleoptile tips from corn (Zea mays). The chloroplast response to blue light was quantified by measurements of the blue light-induced enhancement of a red light-stimulated quenching of chlorophyll a fluorescence. In adaxial (upper) guard cells, low fluence rates of blue light applied under saturating fluence rates of red light enhanced th...

  18. A Comparison of Blue Light and Caffeine Effects on Cognitive Function and Alertness in Humans

    Science.gov (United States)

    Beaven, C. Martyn; Ekström, Johan

    2013-01-01

    The alerting effects of both caffeine and short wavelength (blue) light have been consistently reported. The ability of blue light to enhance alertness and cognitive function via non-image forming neuropathways have been suggested as a non-pharmacological countermeasure for drowsiness across a range of occupational settings. Here we compare and contrast the alerting and psychomotor effects of 240 mg of caffeine and a 1-h dose of ~40 lx blue light in a non-athletic population. Twenty-one healthy subjects performed a computer-based psychomotor vigilance test before and after each of four randomly assigned trial conditions performed on different days: white light/placebo; white light/240 mg caffeine; blue light/placebo; blue light/240 mg caffeine. The Karolinska Sleepiness Scale was used to assess subjective measures of alertness. Both the caffeine only and blue light only conditions enhanced accuracy in a visual reaction test requiring a decision and an additive effect was observed with respect to the fastest reaction times. However, in a test of executive function, where a distraction was included, caffeine exerted a negative effect on accuracy. Furthermore, the blue light only condition consistently outperformed caffeine when both congruent and incongruent distractions were presented. The visual reactions in the absence of a decision or distraction were also enhanced in the blue light only condition and this effect was most prominent in the blue-eyed participants. Overall, blue light and caffeine demonstrated distinct effects on aspects of psychomotor function and have the potential to positively influence a range of settings where cognitive function and alertness are important. Specifically, despite the widespread use of caffeine in competitive sporting environments, the possible impact of blue light has received no research attention. PMID:24282477

  19. A comparison of blue light and caffeine effects on cognitive function and alertness in humans.

    Science.gov (United States)

    Beaven, C Martyn; Ekström, Johan

    2013-01-01

    The alerting effects of both caffeine and short wavelength (blue) light have been consistently reported. The ability of blue light to enhance alertness and cognitive function via non-image forming neuropathways have been suggested as a non-pharmacological countermeasure for drowsiness across a range of occupational settings. Here we compare and contrast the alerting and psychomotor effects of 240 mg of caffeine and a 1-h dose of ~40 lx blue light in a non-athletic population. Twenty-one healthy subjects performed a computer-based psychomotor vigilance test before and after each of four randomly assigned trial conditions performed on different days: white light/placebo; white light/240 mg caffeine; blue light/placebo; blue light/240 mg caffeine. The Karolinska Sleepiness Scale was used to assess subjective measures of alertness. Both the caffeine only and blue light only conditions enhanced accuracy in a visual reaction test requiring a decision and an additive effect was observed with respect to the fastest reaction times. However, in a test of executive function, where a distraction was included, caffeine exerted a negative effect on accuracy. Furthermore, the blue light only condition consistently outperformed caffeine when both congruent and incongruent distractions were presented. The visual reactions in the absence of a decision or distraction were also enhanced in the blue light only condition and this effect was most prominent in the blue-eyed participants. Overall, blue light and caffeine demonstrated distinct effects on aspects of psychomotor function and have the potential to positively influence a range of settings where cognitive function and alertness are important. Specifically, despite the widespread use of caffeine in competitive sporting environments, the possible impact of blue light has received no research attention.

  20. A comparison of blue light and caffeine effects on cognitive function and alertness in humans.

    Directory of Open Access Journals (Sweden)

    C Martyn Beaven

    Full Text Available The alerting effects of both caffeine and short wavelength (blue light have been consistently reported. The ability of blue light to enhance alertness and cognitive function via non-image forming neuropathways have been suggested as a non-pharmacological countermeasure for drowsiness across a range of occupational settings. Here we compare and contrast the alerting and psychomotor effects of 240 mg of caffeine and a 1-h dose of ~40 lx blue light in a non-athletic population. Twenty-one healthy subjects performed a computer-based psychomotor vigilance test before and after each of four randomly assigned trial conditions performed on different days: white light/placebo; white light/240 mg caffeine; blue light/placebo; blue light/240 mg caffeine. The Karolinska Sleepiness Scale was used to assess subjective measures of alertness. Both the caffeine only and blue light only conditions enhanced accuracy in a visual reaction test requiring a decision and an additive effect was observed with respect to the fastest reaction times. However, in a test of executive function, where a distraction was included, caffeine exerted a negative effect on accuracy. Furthermore, the blue light only condition consistently outperformed caffeine when both congruent and incongruent distractions were presented. The visual reactions in the absence of a decision or distraction were also enhanced in the blue light only condition and this effect was most prominent in the blue-eyed participants. Overall, blue light and caffeine demonstrated distinct effects on aspects of psychomotor function and have the potential to positively influence a range of settings where cognitive function and alertness are important. Specifically, despite the widespread use of caffeine in competitive sporting environments, the possible impact of blue light has received no research attention.

  1. Effects of UV-B radiation on tetraspores of Chondrus ocellatus Holm (Rhodophyta), and effects of red and blue light on repair of UV-B-induced damage

    Science.gov (United States)

    Ju, Qing; Xiao, Hui; Wang, You; Tang, Xuexi

    2015-05-01

    We evaluated the effects of red and blue light on the repair of UV-B radiation-induced damage in tetraspores of Chondrus ocellatus Holm. Tetraspores of C. ocellatus were treated with different UV-B radiation levels (0, 36, 72, 108, 144 and 180 J/m2), and thereafter subjected to PAR, darkness, or red or blue light during a 2-h repair stage, each day for 48 days. The diameters and cellular contents of cyclobutane pyrimidine dimmers (CPDs), chlorophyll a (Chl a), phycoerythrin, and UV-B-absorbing mycosporinelike amino acids (MAAs) contents of the tetraspores were determined. Our results show that low doses of UV-B radiation (36 and 72 J/m2) promoted the growth of C. ocellatus; however, increased UV-B radiation gradually reduced the C. ocellatus growth (greater than 72 J/m2). The MAAs (palythine and asterina-330) in C. ocellatus were detected and analyzed by LC/MS. Our results suggest that moderate red light could induce the growth of this alga in aquaculture. In addition, photorepair was inhibited by red light, so there may be some other DNA repair mechanism activated by red light. Blue light promoted the activity of DNA photolyase, greatly improving remediation efficiency. Red and blue lights were found to reduce the capacity of C. ocellatus to form MAAs. Therefore, PAR, red light, and blue light play different roles during the repair processes for damage induced by UV-B radiation.

  2. Exposure to blue light during lunch break: effects on autonomic arousal and behavioral alertness.

    Science.gov (United States)

    Yuda, Emi; Ogasawara, Hiroki; Yoshida, Yutaka; Hayano, Junichiro

    2017-07-11

    Exposures to melanopsin-stimulating (melanopic) component-rich blue light enhance arousal level. We examined their effects in office workers. Eight healthy university office workers were exposed to blue and orange lights for 30 min during lunch break on different days. We compared the effects of light color on autonomic arousal level assessed by heart rate variability (HRV) and behavioral alertness by psychomotor vigilance tests (PVT). Heart rate was higher and high-frequency (HF, 0.150.45 Hz) power of HRV was lower during exposure to the blue light than to orange light. No significant difference with light color was observed, however, in any HRV indices during PVT or in PVT performance after light exposure. Exposure to blue light during lunch break, compared with that to orange light, enhances autonomic arousal during exposure, but has no sustained effect on autonomic arousal or behavioral alertness after exposure.

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

    Science.gov (United States)

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

    Science.gov (United States)

    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. Copyright © 2015. Published by Elsevier B.V.

  5. Effect of a combination of green and blue monochromatic light on broiler immune response.

    Science.gov (United States)

    Zhang, Ziqiang; Cao, Jing; Wang, Zixu; Dong, Yulan; Chen, Yaoxing

    2014-09-05

    Our previous study suggested that green light or blue light would enhance the broiler immune response; this study was conducted to evaluate whether a combination of green and blue monochromatic light would result in improved immune response. A total of 192 Arbor Acre male broilers were exposed to white light, red light, green light, and blue light from 0 to 26 days. From 27 to 49 days, half of the broilers in green light and blue light were switched to blue light (G-B) and green light (B-G), respectively. The levels of anti-Newcastle disease virus (NDV) and anti-bovine serum albumin (BSA) IgG in G-B group were elevated by 11.9-40.3% and 17.4-48.7%, respectively, compared to single monochromatic lights (Plight groups. However, the serum TNF-α concentration in the G-B group was reduced by 3.64-40.5% compared to other groups, and no significant difference was found between the G-B and B-G groups in any type of detection index at the end of the experiment. These results suggested that the combination of G-B and B-G monochromatic light could effectively enhance the antibody titer, the proliferation index of lymphocytes and alleviate the stress response in broilers. Therefore, the combination of green and blue monochromatic light can improve the immune function of broilers. Copyright © 2014 Elsevier B.V. All rights reserved.

  6. Colored lenses suppress blue light-emitting diode light-induced damage in photoreceptor-derived cells.

    Science.gov (United States)

    Hiromoto, Kaho; Kuse, Yoshiki; Tsuruma, Kazuhiro; Tadokoro, Nobuyuki; Kaneko, Nobuyuki; Shimazawa, Masamitsu; Hara, Hideaki

    2016-03-01

    Blue light-emitting diodes (LEDs) in liquid crystal displays emit high levels of blue light, exposure to which is harmful to the retina. Here, we investigated the protective effects of colored lenses in blue LED light-induced damage to 661W photoreceptor-derived cells. We used eight kinds of colored lenses and one lens that reflects blue light. Moreover, we evaluated the relationship between the protective effects of the lens and the transmittance of lens at 464 nm. Lenses of six colors, except for the SY, PN, and reflective coating lenses, strongly decreased the reduction in cell damage induced by blue LED light exposure. The deep yellow lens showed the most protective effect from all the lenses, but the reflective coating lens and pink lens did not show any effects on photoreceptor-derived cell damage. Moreover, these results were correlated with the lens transmittance of blue LED light (464 nm). These results suggest that lenses of various colors, especially deep yellow lenses, may protect retinal photoreceptor cells from blue LED light in proportion to the transmittance for the wavelength of blue LED and the suppression of reactive oxygen species production and cell damage.

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

    Science.gov (United States)

    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

  8. Dissecting blue light signal transduction pathway in leaf epidermis using a pharmacological approach

    NARCIS (Netherlands)

    Zivanovic, Branka D.; Shabala, Lana I.; Elzenga, Theo J. M.; Shabala, Sergey N.

    2015-01-01

    Blue light signalling pathway in broad bean leaf epidermal cells includes key membrane transporters: plasma- and endomembrane channels and pumps of H (+) , Ca (2+) and K (+) ions, and plasma membrane redox system. Blue light signalling pathway in epidermal tissue isolated from the abaxial side of

  9. Luminescence of the InGaN/GaN Blue Light-Emitting Diodes

    Science.gov (United States)

    2000-07-01

    UNCLASSIFIED Defense Technical Information Center Compilation Part Notice ADPO 11314 TITLE: Luminescence of the InGaN/GaN Blue Light -Emitting Diodes...ADP011332 UNCLASSIFIED Luminescence of the InGaN/GaN blue light -emitting diodes J. K. Sheu a), T. W. Yeh and G. C. Chi Optical Sciences Center, National

  10. Effect of phototherapy with turquoise vs. blue LED light of equal irradiance in jaundiced neonates.

    Science.gov (United States)

    Ebbesen, Finn; Vandborg, Pernille K; Madsen, Poul H; Trydal, Torleif; Jakobsen, Lasse H; Vreman, Hendrik J

    2016-02-01

    Blue light with peak emission around 460 nm is the preferred treatment of neonatal hyperbilirubinemia. However, studies using fluorescent light tubes have suggested that turquoise light with peak emission at 490 nm may be more efficient. At present, the predominant light source for phototherapy is light emitting diodes (LEDs). Hence, the aim of this study was to compare the bilirubin-reducing effect in jaundiced neonates treated either with turquoise or with blue LED light with peak emission at 497 or 459 nm, respectively, with equal irradiance on the infants. Infants with gestational age ≥33 wk and uncomplicated hyperbilirubinemia were randomized to either turquoise or blue LED light and were treated for 24 h. The mean irradiance footprint at skin level was 5.2 × 10(15) and 5.1 × 10(15) photons/cm(2)/s, respectively. Forty-six infants received turquoise light and 45 received blue light. The median (95% confidence interval) decrease of total serum bilirubin was 35.3% (32.5; 37.3) and 33.1% (27.1; 36.8) for infants treated with turquoise and blue lights, respectively. The difference was nonsignificant (P = 0.53). The decrease was positively correlated to postnatal age and negatively to birth weight. Using LED light of equal irradiance, turquoise and blue lights had equal bilirubin-reducing effect on hyperbilirubinemia of neonates.

  11. Damage of photoreceptor-derived cells in culture induced by light emitting diode-derived blue light

    Science.gov (United States)

    Kuse, Yoshiki; Ogawa, Kenjiro; Tsuruma, Kazuhiro; Shimazawa, Masamitsu; Hara, Hideaki

    2014-01-01

    Our eyes are increasingly exposed to light from the emitting diode (LED) light of video display terminals (VDT) which contain much blue light. VDTs are equipped with televisions, personal computers, and smart phones. The present study aims to clarify the mechanism underlying blue LED light-induced photoreceptor cell damage. Murine cone photoreceptor-derived cells (661 W) were exposed to blue, white, or green LED light (0.38 mW/cm2). In the present study, blue LED light increased reactive oxygen species (ROS) production, altered the protein expression level, induced the aggregation of short-wavelength opsins (S-opsin), resulting in severe cell damage. While, blue LED light damaged the primary retinal cells and the damage was photoreceptor specific. N-Acetylcysteine (NAC), an antioxidant, protected against the cellular damage induced by blue LED light. Overall, the LED light induced cell damage was wavelength-, but not energy-dependent and may cause more severe retinal photoreceptor cell damage than the other LED light. PMID:24909301

  12. A lighting assembly based on red and blue light-emitting diodes as a lighting source for space agriculture

    Science.gov (United States)

    Avercheva, Olga; Berkovich, Yuliy A.; Smolyanina, Svetlana; Bassarskaya, Elizaveta; Zhigalova, Tatiana; Ptushenko, Vasiliy; Erokhin, Alexei

    Light-emitting diodes (LEDs) are a promising lighting source for space agriculture due to their high efficiency, longevity, safety, and other factors. Assemblies based on red and blue LEDs have been recommended in literature, although not all plants show sufficient productivity in such lighting conditions. Adding of green LEDs proposed in some works was aimed at psychological support for the crew, and not at the improvement of plant growth. We studied the growth and the state of the photosynthetic apparatus in Chinese cabbage (Brassica chinensis L.) plants grown under red (650 nm) and blue (470 nm) light-emitting diodes (LEDs). Plants grown under a high-pressure sodium lamp (HPS lamp) were used as a control. The plants were illuminated with two photosynthetic photon flux levels: nearly 400 µE and about 100 µE. Plants grown under LEDs with 400 µE level, as compared to control plants, showed lower fresh weight, edible biomass, growth rate, and sugar content. The difference in fresh weight and edible biomass was even more pronounced in plants grown with 100 µE level; the data indicate that the adaptability of the test plants to insufficient lighting decreased. Under LEDs, we observed the decreasing of root growth and the absence of transition to the flowering stage, which points to a change in the hormonal balance in plants grown in such lighting conditions. We also found differences in the functioning of the photosynthetic apparatus and its reaction to a low lighting level. We have concluded that a lighting assembly with red and blue LEDs only is insufficient for the plant growth and productivity, and can bring about alterations in their adaptive and regulatory mechanisms. Further studies are needed to optimize the lighting spectrum for space agriculture, taking into account the photosynthetic, phototropic and regulatory roles of light. Using white LEDs or adding far-red and green LEDs might be a promising approach.

  13. Acute exposure to blue wavelength light during memory consolidation improves verbal memory performance.

    Science.gov (United States)

    Alkozei, Anna; Smith, Ryan; Dailey, Natalie S; Bajaj, Sahil; Killgore, William D S

    2017-01-01

    Acute exposure to light within the blue wavelengths has been shown to enhance alertness and vigilance, and lead to improved speed on reaction time tasks, possibly due to activation of the noradrenergic system. It remains unclear, however, whether the effects of blue light extend beyond simple alertness processes to also enhance other aspects of cognition, such as memory performance. The aim of this study was to investigate the effects of a thirty minute pulse of blue light versus placebo (amber light) exposure in healthy normally rested individuals in the morning during verbal memory consolidation (i.e., 1.5 hours after memory acquisition) using an abbreviated version of the California Verbal Learning Test (CVLT-II). At delayed recall, individuals who received blue light (n = 12) during the consolidation period showed significantly better long-delay verbal recall than individuals who received amber light exposure (n = 18), while controlling for the effects of general intelligence, depressive symptoms and habitual wake time. These findings extend previous work demonstrating the effect of blue light on brain activation and alertness to further demonstrate its effectiveness at facilitating better memory consolidation and subsequent retention of verbal material. Although preliminary, these findings point to a potential application of blue wavelength light to optimize memory performance in healthy populations. It remains to be determined whether blue light exposure may also enhance performance in clinical populations with memory deficits.

  14. Blue-light filtering alters angiogenic signaling in human retinal pigmented epithelial cells culture model.

    Science.gov (United States)

    Vila, Natalia; Siblini, Aya; Esposito, Evangelina; Bravo-Filho, Vasco; Zoroquiain, Pablo; Aldrees, Sultan; Logan, Patrick; Arias, Lluis; Burnier, Miguel N

    2017-11-02

    Light exposure and more specifically the spectrum of blue light contribute to the oxidative stress in Age-related macular degeneration (AMD). The purpose of the study was to establish whether blue light filtering could modify proangiogenic signaling produced by retinal pigmented epithelial (RPE) cells under different conditions simulating risk factors for AMD. Three experiments were carried out in order to expose ARPE-19 cells to white light for 48 h with and without blue light-blocking filters (BLF) in different conditions. In each experiment one group was exposed to light with no BLF protection, a second group was exposed to light with BLF protection, and a control group was not exposed to light. The ARPE-19 cells used in each experiment prior to light exposure were cultured for 24 h as follows: Experiment 1) Normoxia, Experiment 2) Hypoxia, and Experiment 3) Lutein supplemented media in normoxia. The media of all groups was harvested after light exposure for sandwich ELISA-based assays to quantify 10 pro-angiogenic cytokines. A significant decrease in angiogenin secretion levels and a significant increase in bFGF were observed following light exposure, compared to dark conditions, in both normoxia and hypoxia conditions. With the addition of a blue light-blocking filter in normoxia, a significant increase in angiogenin levels was observed. Although statistical significance was not achieved, blue light filters reduce light-induced secretion of bFGF and VEGF to near normal levels. This trend is also observed when ARPE-19 cells are grown under hypoxic conditions and when pre-treated with lutein prior to exposure to experimental conditions. Following light exposure, there is a decrease in angiogenin secretion by ARPE-19 cells, which was abrogated with a blue light - blocking filter. Our findings support the position that blue light filtering affects the secretion of angiogenic factors by retinal pigmented epithelial cells under normoxic, hypoxic, and lutein

  15. Human phase response curve to intermittent blue light using a commercially available device

    Science.gov (United States)

    Revell, Victoria L; Molina, Thomas A; Eastman, Charmane I

    2012-01-01

    Light shifts the timing of the circadian clock according to a phase response curve (PRC). To date, all human light PRCs have been to long durations of bright white light. However, melanopsin, the primary photopigment for the circadian system, is most sensitive to short wavelength blue light. Therefore, to optimise light treatment it is important to generate a blue light PRC. We used a small, commercially available blue LED light box, screen size 11.2 × 6.6 cm at ∼50 cm, ∼200 μW cm−2, ∼185 lux. Subjects participated in two 5 day laboratory sessions 1 week apart. Each session consisted of circadian phase assessments to obtain melatonin profiles before and after 3 days of free-running through an ultradian light–dark cycle (2.5 h wake in dim light, 1.5 h sleep in the dark), forced desynchrony protocol. During one session subjects received intermittent blue light (three 30 min pulses over 2 h) once a day for the 3 days of free-running, and in the other session (control) they remained in dim room light, counterbalanced. The time of blue light was varied among subjects to cover the entire 24 h day. For each individual, the phase shift to blue light was corrected for the free-run determined during the control session. The blue light PRC had a broad advance region starting in the morning and extending through the afternoon. The delay region started a few hours before bedtime and extended through the night. This is the first PRC to be constructed to blue light and to a stimulus that could be used in the real world. PMID:22753544

  16. Antimicrobial blue light inactivation of Methicillin-resistant Staphylococcus aureus

    Science.gov (United States)

    Wang, Yucheng; Dai, Tianhong; Gu, Ying

    2016-10-01

    Background: With the increasing emergence of multidrug-resistant (MDR) bacterial strains, there is a pressing need for the development of alternative treatment for infections. Antimicrobial blue light (aBL) has provided a simple and effective approach. Methods: We first investigated the effectiveness of aBL (415 nm) inactivation of USA300 LAClux (a communityacquired Methicillin-resistant Staphylococcus aureus strain) both in the planktonic and biofilm forms. The survival of the bacteria in suspensions was determined by serial dilution and that of the biofilm-embedded bacteria was determined by bioluminescence quantification. Using a mouse model of thermal burn infected with USA300 LAClux, we further assessed the effectiveness of aBL for treating localized infections. Bioluminescence imaging was performed to monitor in real time bacterial viability in vivo. Results: In vitro study showed that, for the planktonic counterpart of the bacteria or the 24-h-old biofilms, an irradiance of 55 mW/cm2 for 60 min resulted in a 4.61 log10 or 2.56 log10 inactivation, respectively. In vivo study using infected mouse burns demonstrated that a 2.56-log10 inactivation was achieved after 100-mW/cm2 irradiation for 62 min. Conclusions: aBL is a potential alternative approach for treating Methicillin-resistant Staphylococcus aureus infections.

  17. Coherent light absorbing by concrete during its hardening

    Science.gov (United States)

    Gorsky, Mykhaylo P.; Maksimyak, Peter P.

    2018-01-01

    In this work changes of concrete reflection coefficient during its hydration were investigated theoretically and experimentally. Diffuse approximation method for concrete light-scattering description during hydration was used and its results were compared with received experimental data. Calculation of scattered and absorption sections for set of particles is described in details. Introduced optical diagnostics method allows performing earlier hydration stages diagnostics of concrete hardening process in comparison with other methods and predicting mechanical properties of produced concrete.

  18. Phytochrome A Mediates Blue-Light Enhancement of Second-Positive Phototropism in Arabidopsis

    Science.gov (United States)

    Sullivan, Stuart; Hart, Jaynee E.; Rasch, Patrick; Walker, Catriona H.; Christie, John M.

    2016-01-01

    Hypocotyl phototropism of etiolated Arabidopsis seedlings is primarily mediated by the blue-light receptor kinase phototropin 1 (phot1). Phot1-mediated curvature to continuous unilateral blue light irradiation (0.5 μmol m−2 s−1) is enhanced by overhead pre-treatment with red light (20 μmol m−2 s−1 for 15 min) through the action of phytochrome (phyA). Here, we show that pre-treatment with blue light is equally as effective in eliciting phototropic enhancement and is dependent on phyA. Although blue light pre-treatment was sufficient to activate early phot1 signaling events, phot1 autophosphorylation in vivo was not found to be saturated, as assessed by subsequently measuring phot1 kinase activity in vitro. However, enhancement effects by red and blue light pre-treatment were not observed at higher intensities of phototropic stimulation (10 μmol m−2 s−1). Phototropic enhancement by red and blue light pre-treatments to 0.5 μmol m−2 s−1 unilateral blue light irradiation was also lacking in transgenic Arabidopsis where PHOT1 expression was restricted to the epidermis. Together, these findings indicate that phyA-mediated effects on phot1 signaling are restricted to low intensities of phototropic stimulation and originate from tissues other than the epidermis. PMID:27014313

  19. Long-term Blue Light Effects on the Histology of Lettuce and Soybean Leaves and Stems

    Science.gov (United States)

    Dougher, Tracy A. O.; Bugbee, Bruce

    2004-01-01

    Blue light (320 to 496 nm) alters hypocotyl and stem elongation and leaf expansion in short-term, cell-level experiments, but histological effects of blue light in long-term studies of whole plants have not been described. We measured cell size and number in stems of soybean (Glycine max L.) and leaves of soybean and lettuce (Lactuca sativa L.), at two blue light fractions. Short-term studies have shown that cell expansion in stems is rapidly inhibited when etiolated tissue is exposed to blue light. However, under long-term light exposure, an increase in the blue light fraction from less than 0.1% to 26% decreased internode length, specifically by inhibiting soybean cell division in stems. In contrast, an increase in blue light fraction from 6% to 26% reduced soybean leaf area by decreasing cell expansion. Surprisingly, lettuce leaf area increased with increasing blue light fraction (0% to 6%), which was attributed to a 3.1-fold increase in cell expansion and a 1.6-fold increase in cell division.

  20. Blue light (470 nm) effectively inhibits bacterial and fungal growth.

    Science.gov (United States)

    De Lucca, A J; Carter-Wientjes, C; Williams, K A; Bhatnagar, D

    2012-12-01

    Blue light (470 nm) LED antimicrobial properties were studied alone against bacteria and with or without the food grade photosensitizer, erythrosine (ERY) against filamentous fungi. Leuconostoc mesenteroides (LM), Bacillus atrophaeus (BA) or Pseudomonas aeruginosa (PA) aliquots were exposed on nutrient agar plates to Array 1 (AR1, 0·2 mW cm(-2)) or Array 2 (AR2, 80 mW cm(-2)), which emitted impure or pure blue light (0-300 J cm(-2)), respectively. Inoculated control (room light only) plates were incubated (48 h) and colonies enumerated. The antifungal properties of blue light combined with ERY (11·4 and 22·8 μmol l(-1)) on Penicillium digitatum (PD) and Fusarium graminearum (FG) conidia were determined. Conidial controls consisted of: no light, room light-treated conidia and ERY plus room light. Light-treated (ERY + blue light) conidial samples were exposed only to AR2 (0-100 J cm(-2)), aliquots spread on potato dextrose agar plates, incubated (48 h, 30°C) and colonies counted. Blue light alone significantly reduced bacterial and FG viability. Combined with ERY, it significantly reduced PD viability. Blue light is lethal to bacteria and filamentous fungi although effectiveness is dependent on light purity, energy levels and microbial genus. Light from two arrays of different blue LEDs significantly reduced bacterial (Leuconostoc mesenteroides, Bacillus atrophaeus and Pseudomonas aeruginosa) viabilities. Significant in vitro viability loss was observed for the filamentous fungi, Penicillium digitatum and Fusarium graminearum when exposed to pure blue light only plus a photosensitizer. F. graminearum viability was significantly reduced by blue light alone. Results suggest that (i) the amount of significant loss in bacterial viability observed for blue light that is pure or with traces of other wavelengths is genus dependent and (ii) depending on fungal genera, pure blue light is fungicidal with or without a photosensitizer. © 2012 The Society for

  1. Lethal effect of blue light on strawberry leaf beetle, Galerucella grisescens (Coleoptera: Chrysomelidae).

    Science.gov (United States)

    Hori, Masatoshi; Suzuki, Ayako

    2017-06-02

    In a previous study, we found that blue-light irradiation kills insects such as fruit flies, mosquitos, and flour beetles. However, the lethal effects of blue light on coleopteran field crop pests have not been investigated. Chrysomelidae, a major family in phytophagous beetles, includes many species of crop pests. We investigated the lethal effect of blue light on chrysomelid beetles by examining the mortality of the strawberry leaf beetle Galerucella grisescens irradiated with different wavelengths of blue light during the non-mobile egg or pupal stage by using light-emitting diodes. Fifty to seventy percent of beetles irradiated with 407, 417, 438, or 465-nm lights at 15 × 10 18 photons·m -2 ·s -1 during the egg stage died before hatching; ca. 90% of hatchlings irradiated with 438-nm light during the egg stage died before eclosion; and 35-55% of beetles irradiated with 407, 417, 454, and 465-nm lights at the same intensity during the pupal stage died before eclosion. Field crop pests are considered to have high tolerance to blue light because they are usually exposed to sunlight in their natural habitats. However, this study suggests that blue light can kill some field crop as well as household insect pests.

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

    Science.gov (United States)

    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.

  3. Structure and properties of visible-light absorbing homodisperse nanoparticle

    Energy Technology Data Exchange (ETDEWEB)

    Benedict, Jason

    2018-04-05

    Broadly, the scientific progress from this award focused in two main areas: developing time-resolved X-ray diffraction methods and the synthesis and characterization of molecular systems relevant to solar energy harvesting. The knowledge of photo‐induced non‐equilibrium states is central to our understanding of processes involved in solar‐energy capture. More specifically, knowledge of the geometry changes on excitation and their relation to lifetimes and variation with adsorption of chromophores on the substrates is of importance for the design of molecular devices used in light capture.

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

    Science.gov (United States)

    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

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

    Science.gov (United States)

    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. Copyright © 2013 Elsevier Ltd. All rights reserved.

  6. System responses to equal doses of photosynthetically usable radiation of blue, green, and red light in the marine diatom Phaeodactylum tricornutum.

    Directory of Open Access Journals (Sweden)

    Kristin Collier Valle

    Full Text Available Due to the selective attenuation of solar light and the absorption properties of seawater and seawater constituents, free-floating photosynthetic organisms have to cope with rapid and unpredictable changes in both intensity and spectral quality. We have studied the transcriptional, metabolic and photo-physiological responses to light of different spectral quality in the marine diatom Phaeodactylum tricornutum through time-series studies of cultures exposed to equal doses of photosynthetically usable radiation of blue, green and red light. The experiments showed that short-term differences in gene expression and profiles are mainly light quality-dependent. Transcription of photosynthesis-associated nuclear genes was activated mainly through a light quality-independent mechanism likely to rely on chloroplast-to-nucleus signaling. In contrast, genes encoding proteins important for photoprotection and PSII repair were highly dependent on a blue light receptor-mediated signal. Changes in energy transfer efficiency by light-harvesting pigments were spectrally dependent; furthermore, a declining trend in photosynthetic efficiency was observed in red light. The combined results suggest that diatoms possess a light quality-dependent ability to activate photoprotection and efficient repair of photodamaged PSII. In spite of approximately equal numbers of PSII-absorbed quanta in blue, green and red light, the spectral quality of light is important for diatom responses to ambient light conditions.

  7. System responses to equal doses of photosynthetically usable radiation of blue, green, and red light in the marine diatom Phaeodactylum tricornutum.

    Science.gov (United States)

    Valle, Kristin Collier; Nymark, Marianne; Aamot, Inga; Hancke, Kasper; Winge, Per; Andresen, Kjersti; Johnsen, Geir; Brembu, Tore; Bones, Atle M

    2014-01-01

    Due to the selective attenuation of solar light and the absorption properties of seawater and seawater constituents, free-floating photosynthetic organisms have to cope with rapid and unpredictable changes in both intensity and spectral quality. We have studied the transcriptional, metabolic and photo-physiological responses to light of different spectral quality in the marine diatom Phaeodactylum tricornutum through time-series studies of cultures exposed to equal doses of photosynthetically usable radiation of blue, green and red light. The experiments showed that short-term differences in gene expression and profiles are mainly light quality-dependent. Transcription of photosynthesis-associated nuclear genes was activated mainly through a light quality-independent mechanism likely to rely on chloroplast-to-nucleus signaling. In contrast, genes encoding proteins important for photoprotection and PSII repair were highly dependent on a blue light receptor-mediated signal. Changes in energy transfer efficiency by light-harvesting pigments were spectrally dependent; furthermore, a declining trend in photosynthetic efficiency was observed in red light. The combined results suggest that diatoms possess a light quality-dependent ability to activate photoprotection and efficient repair of photodamaged PSII. In spite of approximately equal numbers of PSII-absorbed quanta in blue, green and red light, the spectral quality of light is important for diatom responses to ambient light conditions.

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

    Science.gov (United States)

    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.

  9. Anion channels and the stimulation of anthocyanin accumulation by blue light in Arabidopsis seedlings

    Science.gov (United States)

    Noh, B.; Spalding, E. P.; Evans, M. H. (Principal Investigator)

    1998-01-01

    Activation of anion channels by blue light begins within seconds of irradiation in seedlings and is related to the ensuing growth inhibition. 5-Nitro-2-(3-phenylpropylamino)-benzoic acid (NPPB) is a potent, selective, and reversible blocker of these anion channels in Arabidopsis thaliana. Here we show that 20 microM NPPB blocked 72% of the blue-light-induced accumulation of anthocyanin pigments in seedlings. Feeding biosynthetic intermediates to wild-type and tt5 seedlings provided evidence that NPPB prevented blue light from up-regulating one or more steps between and including phenylalanine ammonia lyase and chalcone isomerase. NPPB was found to have no significant effect on the blue-light-induced increase in transcript levels of PAL1, CHS, CHI, or DFR, which are genes that encode anthocyanin-biosynthetic enzymes. Immunoblots revealed that NPPB also did not inhibit the accumulation of the chalcone synthase, chalcone isomerase, or flavanone-3-hydroxylase proteins. This is in contrast to the reduced anthocyanin accumulation displayed by a mutant lacking the HY4 blue-light receptor, as hy4 displayed reduced expression of the above enzymes. Taken together, the data indicate that blue light acting through HY4 leads to an increase in the amount of biosynthetic enzymes but blue light must also act through a separate, anion-channel-dependent system to create a fully functional biosynthetic pathway.

  10. A Raf-like protein kinase BHP mediates blue light-dependent stomatal opening.

    Science.gov (United States)

    Hayashi, Maki; Inoue, Shin-Ichiro; Ueno, Yoshihisa; Kinoshita, Toshinori

    2017-03-30

    Stomata in the plant epidermis open in response to blue light and affect photosynthesis and plant growth by regulating CO 2 uptake and transpiration. In stomatal guard cells under blue light, plasma membrane H + -ATPase is phosphorylated and activated via blue light-receptor phototropins and a signaling mediator BLUS1, and H + -ATPase activation drives stomatal opening. However, details of the signaling between phototropins and H + -ATPase remain largely unknown. In this study, through a screening of specific inhibitors for the blue light-dependent H + -ATPase phosphorylation in guard cells, we identified a Raf-like protein kinase, BLUE LIGHT-DEPENDENT H + -ATPASE PHOSPHORYLATION (BHP). Guard cells in the bhp mutant showed impairments of stomatal opening and H + -ATPase phosphorylation in response to blue light. BHP is abundantly expressed in the cytosol of guard cells and interacts with BLUS1 both in vitro and in vivo. Based on these results, BHP is a novel signaling mediator in blue light-dependent stomatal opening, likely downstream of BLUS1.

  11. On the radiative effects of light-absorbing impurities on snowpack evolution

    Science.gov (United States)

    Dumont, M.; Tuzet, F.; Lafaysse, M.; Arnaud, L.; Picard, G.; Lejeune, Y.; Lamare, M.; Morin, S.; Voisin, D.; Di Mauro, B.

    2017-12-01

    The presence of light absorbing impurities in snow strongly decreases snow reflectance leading to an increase in the amount of solar energy absorbed by the snowpack. This effect is also known as impurities direct radiative effect. The change in the amount of energy absorbed by the snowpack modifies the temperature profile inside the snowpack and in turn snow metamorphism (impurities indirect radiative effects). In this work, we used the detailed snowpack model SURFEX/ISBA-Crocus with an explicit representation of snow light-absorbing impurities content (Tuzet et al., 2017) fed by medium-resolution ALADIN-Climate atmospheric model to represent dust and black carbon atmospheric deposition fluxes. The model is used at two sites: Col de Porte (medium elevation site in the French Alps) and Torgnon (high elevation site in the Italian Alps). The simulations are compared to in-situ observations and used to quantify the effects of light-absorbing impurities on snow melt rate and timing. The respective parts of the direct and indirect radiative effects of light-absorbing impurities in snow are also computed for the two sites, emphasizing the need to account for the interactions between snow metamorphism and LAI radiative properties, to accurately predict the effects of light-absorbing impurities in snow. Moreover, we describe how automated hyperspectral reflectance can be used to estimate effective impurities surface content in snow. Finally we demonstrate how these reflectances measurements either from in situ or satellite data can be used via an assimilation scheme to constrain snowpack ensemble simulations and better predict the snowpack state and evolution.

  12. Stomatal limitation to carbon gain in Paphiopedilum sp. (Orchidaceae) and its reversal by blue light

    Energy Technology Data Exchange (ETDEWEB)

    Zeiger, E.; Grivet, C.; Assmann, S.M.; Dietzer, G.F.; Hannegan, M.W.

    1985-02-01

    Leaves from Paphiopedilum sp. (Orchidaceae) having achlorophyllous stomata, show reduced levels of stomatal conductance when irradiated with red light, as compared with either the related, chlorophyllous genus Phragmipedium or with their response to blue light. These reduced levels of stomatal conductance, and the failure of isolated Paphiopedilum stomata to open under red irradiation indicates that the small stomatal response measured in the intact leaf under red light is indirect. The overall low levels of stomatal conductance observed in Paphiopedilum leaves under most growing conditions and their capacity to increase stomatal conductance in response to blue light suggested that growth and carbon gain in Paphiopedilum could be enhanced in a blue light-enriched environment. To test that hypothesis, plants of Paphiopedilum acmodontum were grown in controlled growth chambers under daylight fluorescent light, with or without blue light supplementation. Blue light enrichment resulted in significantly higher growth rates over a 3 to 4 week growing period, with all evidence indicating that the blue light effect was a stomatal response. Manipulations of stomatal properties aimed at long-term carbon gains could have agronomic applications.

  13. Antibacterial Activity of Blue Light against Nosocomial Wound Pathogens Growing Planktonically and as Mature Biofilms.

    Science.gov (United States)

    Halstead, Fenella D; Thwaite, Joanne E; Burt, Rebecca; Laws, Thomas R; Raguse, Marina; Moeller, Ralf; Webber, Mark A; Oppenheim, Beryl A

    2016-07-01

    The blue wavelengths within the visible light spectrum are intrinisically antimicrobial and can photodynamically inactivate the cells of a wide spectrum of bacteria (Gram positive and negative) and fungi. Furthermore, blue light is equally effective against both drug-sensitive and -resistant members of target species and is less detrimental to mammalian cells than is UV radiation. Blue light is currently used for treating acnes vulgaris and Helicobacter pylori infections; the utility for decontamination and treatment of wound infections is in its infancy. Furthermore, limited studies have been performed on bacterial biofilms, the key growth mode of bacteria involved in clinical infections. Here we report the findings of a multicenter in vitro study performed to assess the antimicrobial activity of 400-nm blue light against bacteria in both planktonic and biofilm growth modes. Blue light was tested against a panel of 34 bacterial isolates (clinical and type strains) comprising Acinetobacter baumannii, Enterobacter cloacae, Stenotrophomonas maltophilia, Pseudomonas aeruginosa, Escherichia coli, Staphylococcus aureus, Enterococcus faecium, Klebsiella pneumoniae, and Elizabethkingia meningoseptica All planktonic-phase bacteria were susceptible to blue light treatment, with the majority (71%) demonstrating a ≥5-log10 decrease in viability after 15 to 30 min of exposure (54 J/cm(2) to 108 J/cm(2)). Bacterial biofilms were also highly susceptible to blue light, with significant reduction in seeding observed for all isolates at all levels of exposure. These results warrant further investigation of blue light as a novel decontamination strategy for the nosocomial environment, as well as additional wider decontamination applications. Blue light shows great promise as a novel decontamination strategy for the nosocomial environment, as well as additional wider decontamination applications (e.g., wound closure during surgery). This warrants further investigation. © Crown

  14. Antibacterial Activity of Blue Light against Nosocomial Wound Pathogens Growing Planktonically and as Mature Biofilms

    Science.gov (United States)

    Thwaite, Joanne E.; Burt, Rebecca; Laws, Thomas R.; Raguse, Marina; Moeller, Ralf; Webber, Mark A.; Oppenheim, Beryl A.

    2016-01-01

    ABSTRACT The blue wavelengths within the visible light spectrum are intrinisically antimicrobial and can photodynamically inactivate the cells of a wide spectrum of bacteria (Gram positive and negative) and fungi. Furthermore, blue light is equally effective against both drug-sensitive and -resistant members of target species and is less detrimental to mammalian cells than is UV radiation. Blue light is currently used for treating acnes vulgaris and Helicobacter pylori infections; the utility for decontamination and treatment of wound infections is in its infancy. Furthermore, limited studies have been performed on bacterial biofilms, the key growth mode of bacteria involved in clinical infections. Here we report the findings of a multicenter in vitro study performed to assess the antimicrobial activity of 400-nm blue light against bacteria in both planktonic and biofilm growth modes. Blue light was tested against a panel of 34 bacterial isolates (clinical and type strains) comprising Acinetobacter baumannii, Enterobacter cloacae, Stenotrophomonas maltophilia, Pseudomonas aeruginosa, Escherichia coli, Staphylococcus aureus, Enterococcus faecium, Klebsiella pneumoniae, and Elizabethkingia meningoseptica. All planktonic-phase bacteria were susceptible to blue light treatment, with the majority (71%) demonstrating a ≥5-log10 decrease in viability after 15 to 30 min of exposure (54 J/cm2 to 108 J/cm2). Bacterial biofilms were also highly susceptible to blue light, with significant reduction in seeding observed for all isolates at all levels of exposure. These results warrant further investigation of blue light as a novel decontamination strategy for the nosocomial environment, as well as additional wider decontamination applications. IMPORTANCE Blue light shows great promise as a novel decontamination strategy for the nosocomial environment, as well as additional wider decontamination applications (e.g., wound closure during surgery). This warrants further

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

    Science.gov (United States)

    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. Homogeneous photosensitized degradation of pharmaceuticals by using red light LED as light source and methylene blue as photosensitizer

    NARCIS (Netherlands)

    Ye, Y.; Bruning, H.; Yntema, D.; Mayer, M.; Rijnaarts, H.

    2017-01-01

    Research on employing advanced oxidation processes (AOPs) for pharmaceuticals removal is gaining interests. However, detrimental effects of background water constituents in complex water matrices are limiting their implementation. In this study, we report red light induced methylene blue

  17. User-Wearable Devices that Monitor Exposure to Blue Light and Recommend Adjustments Thereto

    Science.gov (United States)

    Lee, Yong Jin (Inventor)

    2017-01-01

    Described herein are user-wearable devices that include an optical sensor, and methods for use therewith. In certain embodiments, an optical sensor of a user-wearable device (e.g., a wrist-worn device) is used to detect blue light that is incident on the optical sensor and to produce a blue light detection signal indicative thereof, and thus, indicative of the response of the user's intrinsically photosensitive Retinal Ganglion Cells (ipRGCs). In dependence on the blue light detection signal, there is a determination of a metric indicative of an amount of blue light detected by the optical sensor. The metric is compared to a corresponding threshold, and a user notification is triggered in dependence on results of the comparing, wherein the user notification informs a person wearing the user-wearable device to adjust their exposure to light.

  18. Blue light cystoscopy with hexylaminolevulinate: Our 7 years experience

    Directory of Open Access Journals (Sweden)

    Vito Lacetera

    2017-03-01

    Full Text Available Aim: The objective of the present study is to evaluate the diagnostic accuracy of hexylaminolevulinate (HAL blue light cystoscopy compared with standard white light cystoscopy (WLC in daily practice. Materials and methods: An observational, comparative, controlled (within patient study was carried out at our Center. 61 consecutive patients with suspected or confirmed bladder cancer were recruited for the study from January 2008 until January 2015. Patients with suspected bladder cancer (positive cytology with negative WLC or history of previous high-grade NMIBC or CIS were included in the study. Biopsies/resection of each positive lesion/suspicious areas were always taken after the bladder was inspected under WLC and BLC. Diagnoses of bladder tumor or CIS were considered as positive results, and the presence of normal urothelium in the biopsy specimen as negative result. Results: 61 BLC were performed. 15/61 (24.5% with suspected initial diagnosis of NMIBC and 46/61 (75.5% with a history of high-risk non-muscle invasive bladder cancer (NMIBC. We performed a total of 173 biopsies/TURBT of suspicious areas: 129 positive only to the BLC and 44 both positive to WLC and BLC. 84/173 biopsies/TURBT were positive for cancer. All 84 NMIBC were positive to the BLC, while 35/84 were positive to the WLC with a sensitivity of BLC and WLC respectively of 100% and 41.7%. Sensitivity of WLC for highgrade NMIBC and CIS was 34.1% and 39% respectively while sensitivity of BLC for high-grade NMIBC and CIS was 100%. The specificity of the WLC was 79.9% compared to 48.5% of the BLC. The positive predictive value of BLC and WLC were respectively 48% (95% CI: 0.447-0.523 and 79% (95% CI: 0.856-0.734. Conclusions: Our data confirm those reported in the literature: BLC increases the detection rate of NMIBC particularly in high risk patients (history of CIS or high grade. BLC is a powerful diagnostic tool in the diagnosis of bladder cancer if malignancy is suspected

  19. Protective effect of blue-light shield eyewear for adults against light pollution from self-luminous devices used at night.

    Science.gov (United States)

    Ayaki, Masahiko; Hattori, Atsuhiko; Maruyama, Yusuke; Nakano, Masaki; Yoshimura, Michitaka; Kitazawa, Momoko; Negishi, Kazuno; Tsubota, Kazuo

    2016-01-01

    We investigated sleep quality and melatonin in 12 adults who wore blue-light shield or control eyewear 2 hours before sleep while using a self-luminous portable device, and assessed visual quality for the two eyewear types. Overnight melatonin secretion was significantly higher after using the blue-light shield (P blue-light shield (P blue-light shield as providing acceptable visual quality.

  20. Blue light emitting diodes (LEDs) as an energy source in Chlorella fusca and Synechococcus nidulans cultures.

    Science.gov (United States)

    Duarte, Jessica Hartwig; Costa, Jorge Alberto Vieira

    2018-01-01

    LEDs have narrow wavelength bands, which can influence microalgae biomass. This study pioneers the evaluation of blue LEDs as an energy source in Chlorella fusca and Synechococcus nidulans cultures. Blue LEDs increased the specific growth rate in Synechococcus nidulans LEB 115 cultures by 80% compared to the standard light used in indoor cultivations. Moreover, blue LEDs also induced lipid accumulation in Chlorella fusca LEB 111 cells, yielding concentrations of this bioproduct of up to 23% (ww -1 ). The chlorophylls and carotenoids were photostimulated proportionally to the LED light intensity. When the intensity of the blue LEDs was increased from 50 to 150μmolm -2 s -1 , the biomass accumulated up to 4.5 and 2.4 times more chlorophylls and carotenoids, respectively. The potential of blue LEDs as an alternative environmentally friendly light source to stimulate biomass and metabolite production for different purposes was demonstrated. Copyright © 2017 Elsevier Ltd. All rights reserved.

  1. Reactive oxygen species production in mitochondria of human gingival fibroblast induced by blue light irradiation.

    Science.gov (United States)

    Yoshida, Ayaka; Yoshino, Fumihiko; Makita, Tetsuya; Maehata, Yojiro; Higashi, Kazuyoshi; Miyamoto, Chihiro; Wada-Takahashi, Satoko; Takahashi, Shun-suke; Takahashi, Osamu; Lee, Masaichi Chang-il

    2013-12-05

    In recent years, it has become well known that the production of reactive oxygen species (ROS) induced by blue-light irradiation causes adverse effects of photo-aging, such as age-related macular degeneration of the retina. Thus, orange-tinted glasses are used to protect the retina during dental treatment involving blue-light irradiation (e.g., dental resin restorations or tooth bleaching treatments). However, there are few studies examining the effects of blue-light irradiation on oral tissue. For the first time, we report that blue-light irradiation by quartz tungsten halogen lamp (QTH) or light-emitting diode (LED) decreased cell proliferation activity of human gingival fibroblasts (HGFs) in a time-dependent manner (LED irradiation compared with cytotoxicity after QTH irradiation. These results suggest that blue light irradiation, especially by LED light sources used in dental aesthetic treatment, might have adverse effects on human gingival tissue. Hence, this necessitates the development of new dental aesthetic treatment methods and/or techniques to protect HGFs from blue light irradiation during dental therapy. Copyright © 2013 Elsevier B.V. All rights reserved.

  2. Blue Light for Enhancing Alertness in Space Missions

    Data.gov (United States)

    National Aeronautics and Space Administration — This is the final year of a directed research project that had reduced aims due to an unexpected funding reduction. The goal is to study the efficacy of blue or...

  3. Suppression of vagal cardiac modulation by blue light in healthy subjects.

    Science.gov (United States)

    Yuda, Emi; Ogasawara, Hiroki; Yoshida, Yutaka; Hayano, Junichiro

    2016-10-05

    In the contemporary life environments, our body is increasingly exposed to various sources of colored light, which may affect our physiological functions as non-image-forming effects. We examined the impacts of colored lights on the autonomic functions by the analysis of heart rate variability (HRV). A lighting device consisting of four organic light-emitting diode (OLED) modules (55 × 55 mm 2 ) with adjustable red-green-blue color was secured 24 cm above the eyes of subject lying supine in a light-shielded laboratory. Following a 15-min supine rest, electrocardiogram and respiration were measured continuously during 3-min darkness, 6-min colored OLED illumination, and 3-min darkness under paced breathing (15 breath/min). The measurements were repeated at a 45-min interval for red, green, and blue lights with melanopsin-stimulating photon flux density (MSPFD) of 0.00, 0.10, and 0.20 μmol/m 2 /s, respectively, in 12 healthy subjects (23 ± 2 years, two females). Additionally, the effects of blue lights with 0.20, 0.10, and 0.04 μmol/m 2 /s MSPFD were examined in four healthy subjects (25-39 years, two females). HRV was analyzed for low-frequency (LF, 0.04-0.15 Hz) and high-frequency (HF, 0.20-0.30 Hz) power and LF-to-HF ratio (LF/HF). Compared to darkness before lighting, HF power decreased (P lighting on average of all color lights, whereas HF power showed a greater decrease with blue light than with red and green lights (P lighting (P blue light with 0.20 μmol/m 2 /s MSPFD (P blue light in healthy subjects most likely through melanopsin-dependent non-image-forming effect.

  4. Sensitivity of Seven Diverse Species to Blue and Green Light: Interactions with Photon Flux

    Science.gov (United States)

    Snowden, M. Chase; Cope, Kevin R.; Bugbee, Bruce

    2016-01-01

    Despite decades of research, the effects of spectral quality on plant growth, and development are not well understood. Much of our current understanding comes from studies with daily integrated light levels that are less than 10% of summer sunlight thus making it difficult to characterize interactions between light quality and quantity. Several studies have reported that growth is increased under fluorescent lamps compared to mixtures of wavelengths from LEDs. Conclusions regarding the effect of green light fraction range from detrimental to beneficial. Here we report the effects of eight blue and green light fractions at two photosynthetic photon fluxes (PPF; 200 and 500 μmol m-2 s-1; with a daily light integral of 11.5 and 29 mol m-2 d-1) on growth (dry mass), leaf expansion, stem and petiole elongation, and whole-plant net assimilation of seven diverse plant species. The treatments included cool, neutral, and warm white LEDs, and combinations of blue, green and/or red LEDs. At the higher PPF (500), increasing blue light in increments from 11 to 28% reduced growth in tomato, cucumber, and pepper by 22, 26, and 14% respectively, but there was no statistically significant effect on radish, soybean, lettuce or wheat. At the lower PPF (200), increasing blue light reduced growth only in tomato (41%). The effects of blue light on growth were mediated by changes in leaf area and radiation capture, with minimal effects on whole-plant net-assimilation. In contrast to the significant effects of blue light, increasing green light in increments from 0 to 30% had a relatively small effect on growth, leaf area and net assimilation at either low or high PPF. Surprisingly, growth of three of the seven species was not reduced by a treatment with 93% green light compared to the broad spectrum treatments. Collectively, these results are consistent with a shade avoidance response associated with either low blue or high green light fractions. PMID:27706176

  5. Sensitivity of Seven Diverse Species to Blue and Green Light: Interactions with Photon Flux.

    Directory of Open Access Journals (Sweden)

    M Chase Snowden

    Full Text Available Despite decades of research, the effects of spectral quality on plant growth, and development are not well understood. Much of our current understanding comes from studies with daily integrated light levels that are less than 10% of summer sunlight thus making it difficult to characterize interactions between light quality and quantity. Several studies have reported that growth is increased under fluorescent lamps compared to mixtures of wavelengths from LEDs. Conclusions regarding the effect of green light fraction range from detrimental to beneficial. Here we report the effects of eight blue and green light fractions at two photosynthetic photon fluxes (PPF; 200 and 500 μmol m-2 s-1; with a daily light integral of 11.5 and 29 mol m-2 d-1 on growth (dry mass, leaf expansion, stem and petiole elongation, and whole-plant net assimilation of seven diverse plant species. The treatments included cool, neutral, and warm white LEDs, and combinations of blue, green and/or red LEDs. At the higher PPF (500, increasing blue light in increments from 11 to 28% reduced growth in tomato, cucumber, and pepper by 22, 26, and 14% respectively, but there was no statistically significant effect on radish, soybean, lettuce or wheat. At the lower PPF (200, increasing blue light reduced growth only in tomato (41%. The effects of blue light on growth were mediated by changes in leaf area and radiation capture, with minimal effects on whole-plant net-assimilation. In contrast to the significant effects of blue light, increasing green light in increments from 0 to 30% had a relatively small effect on growth, leaf area and net assimilation at either low or high PPF. Surprisingly, growth of three of the seven species was not reduced by a treatment with 93% green light compared to the broad spectrum treatments. Collectively, these results are consistent with a shade avoidance response associated with either low blue or high green light fractions.

  6. Sensitivity of Seven Diverse Species to Blue and Green Light: Interactions with Photon Flux.

    Science.gov (United States)

    Snowden, M Chase; Cope, Kevin R; Bugbee, Bruce

    2016-01-01

    Despite decades of research, the effects of spectral quality on plant growth, and development are not well understood. Much of our current understanding comes from studies with daily integrated light levels that are less than 10% of summer sunlight thus making it difficult to characterize interactions between light quality and quantity. Several studies have reported that growth is increased under fluorescent lamps compared to mixtures of wavelengths from LEDs. Conclusions regarding the effect of green light fraction range from detrimental to beneficial. Here we report the effects of eight blue and green light fractions at two photosynthetic photon fluxes (PPF; 200 and 500 μmol m-2 s-1; with a daily light integral of 11.5 and 29 mol m-2 d-1) on growth (dry mass), leaf expansion, stem and petiole elongation, and whole-plant net assimilation of seven diverse plant species. The treatments included cool, neutral, and warm white LEDs, and combinations of blue, green and/or red LEDs. At the higher PPF (500), increasing blue light in increments from 11 to 28% reduced growth in tomato, cucumber, and pepper by 22, 26, and 14% respectively, but there was no statistically significant effect on radish, soybean, lettuce or wheat. At the lower PPF (200), increasing blue light reduced growth only in tomato (41%). The effects of blue light on growth were mediated by changes in leaf area and radiation capture, with minimal effects on whole-plant net-assimilation. In contrast to the significant effects of blue light, increasing green light in increments from 0 to 30% had a relatively small effect on growth, leaf area and net assimilation at either low or high PPF. Surprisingly, growth of three of the seven species was not reduced by a treatment with 93% green light compared to the broad spectrum treatments. Collectively, these results are consistent with a shade avoidance response associated with either low blue or high green light fractions.

  7. The effects of low-intensity narrow-band blue-light treatment compared to bright white-light treatment in sub-syndromal seasonal affective disorder

    NARCIS (Netherlands)

    Meesters, Ybe; Winthorst, Wim H.; Duijzer, Wianne; Bos, Elisabeth; V, Hommes,

    2016-01-01

    Background The discovery of a novel photoreceptor in the retinal ganglion cells with a highest sensitivity of 470-490 nm blue light has led to research on the effects of short-wavelength light in humans. Several studies have explored the efficacy of monochromatic blue or blue-enriched light in the

  8. Pulsing blue light through closed eyelids: effects on acute melatonin suppression and phase shifting of dim light melatonin onset

    Directory of Open Access Journals (Sweden)

    Figueiro MG

    2014-12-01

    Full Text Available Mariana G Figueiro, Barbara Plitnick, Mark S Rea Lighting Research Center, Rensselaer Polytechnic Institute, Troy, NY, USA Abstract: Circadian rhythm disturbances parallel the increased prevalence of sleep disorders in older adults. Light therapies that specifically target regulation of the circadian system in principle could be used to treat sleep disorders in this population. Current recommendations for light treatment require the patients to sit in front of a bright light box for at least 1 hour daily, perhaps limiting their willingness to comply. Light applied through closed eyelids during sleep might not only be efficacious for changing circadian phase but also lead to better compliance because patients would receive light treatment while sleeping. Reported here are the results of two studies investigating the impact of a train of 480 nm (blue light pulses presented to the retina through closed eyelids on melatonin suppression (laboratory study and on delaying circadian phase (field study. Both studies employed a sleep mask that provided narrowband blue light pulses of 2-second duration every 30 seconds from arrays of light-emitting diodes. The results of the laboratory study demonstrated that the blue light pulses significantly suppressed melatonin by an amount similar to that previously shown in the same protocol at half the frequency (ie, one 2-second pulse every minute for 1 hour. The results of the field study demonstrated that blue light pulses given early in the sleep episode significantly delayed circadian phase in older adults; these results are the first to demonstrate the efficacy and practicality of light treatment by a sleep mask aimed at adjusting circadian phase in a home setting. Keywords: circadian phase, dim light melatonin onset, light through closed eyelids, blue light, sleep

  9. Morning and Evening Blue-Enriched Light Exposure Alters Metabolic Function in Normal Weight Adults.

    Science.gov (United States)

    Cheung, Ivy N; Zee, Phyllis C; Shalman, Dov; Malkani, Roneil G; Kang, Joseph; Reid, Kathryn J

    2016-01-01

    Increasing evidence points to associations between light-dark exposure patterns, feeding behavior, and metabolism. This study aimed to determine the acute effects of 3 hours of morning versus evening blue-enriched light exposure compared to dim light on hunger, metabolic function, and physiological arousal. Nineteen healthy adults completed this 4-day inpatient protocol under dim light conditions (blue-enriched light exposure on Day 3 starting either 0.5 hours after wake (n = 9; morning group) or 10.5 hours after wake (n = 10; evening group). All participants remained in dim light on Day 2 to serve as their baseline. Subjective hunger and sleepiness scales were collected hourly. Blood was sampled at 30-minute intervals for 4 hours in association with the light exposure period for glucose, insulin, cortisol, leptin, and ghrelin. Homeostatic model assessment of insulin resistance (HOMA-IR) and area under the curve (AUC) for insulin, glucose, HOMA-IR and cortisol were calculated. Comparisons relative to baseline were done using t-tests and repeated measures ANOVAs. In both the morning and evening groups, insulin total area, HOMA-IR, and HOMA-IR AUC were increased and subjective sleepiness was reduced with blue-enriched light compared to dim light. The evening group, but not the morning group, had significantly higher glucose peak value during blue-enriched light exposure compared to dim light. There were no other significant differences between the morning or the evening groups in response to blue-enriched light exposure. Blue-enriched light exposure acutely alters glucose metabolism and sleepiness, however the mechanisms behind this relationship and its impacts on hunger and appetite regulation remain unclear. These results provide further support for a role of environmental light exposure in the regulation of metabolism.

  10. Effect of Twice-Daily Blue Light Treatment on Matrix-Rich Biofilm Development.

    Science.gov (United States)

    de Sousa, Denise Lins; Lima, Ramille Araújo; Zanin, Iriana Carla; Klein, Marlise I; Janal, Malvin N; Duarte, Simone

    2015-01-01

    The use of blue light has been proposed as a direct means of affecting local bacterial infections, however the use of blue light without a photosensitizer to prevent the biofilm development has not yet been explored. The aim of this study was to determine how the twice-daily treatment with blue light affects the development and composition of a matrix-rich biofilm. Biofilms of Streptococcus mutans UA159 were formed on saliva-coated hydroxyapatite discs for 5 days. The biofilms were exposed twice-daily to non-coherent blue light (LumaCare; 420 nm) without a photosensitizer. The distance between the light and the sample was 1.0 cm; energy density of 72 J cm-2; and exposure time of 12 min 56 s. Positive and negative controls were twice-daily 0.12% chlorhexidine (CHX) and 0.89% NaCl, respectively. Biofilms were analyzed for bacterial viability, dry-weight, and extra (EPS-insoluble and soluble) and intracellular (IPS) polysaccharides. Variable pressure scanning electron microscopy and confocal scanning laser microscopy were used to check biofilm morphology and bacterial viability, respectively. When biofilms were exposed to twice-daily blue light, EPS-insoluble was reduced significantly more than in either control group (CHX and 0.89% NaCl). Bacterial viability and dry weight were also reduced relative to the negative control (0.89% NaCl) when the biofilms were treated with twice-daily blue light. Different morphology was also visible when the biofilms were treated with blue light. Twice-daily treatment with blue light without a photosensitizer is a promising mechanism for the inhibition of matrix-rich biofilm development.

  11. Extending "Deep Blue" Aerosol Retrieval Coverage to Cases of Absorbing Aerosols Above Clouds: Sensitivity Analysis and First Case Studies

    Science.gov (United States)

    Sayer, A. M.; Hsu, N. C.; Bettenhausen, C.; Lee, J.; Redemann, J.; Schmid, B.; Shinozuka, Y.

    2016-01-01

    Cases of absorbing aerosols above clouds (AACs), such as smoke or mineral dust, are omitted from most routinely processed space-based aerosol optical depth (AOD) data products, including those from the Moderate Resolution Imaging Spectroradiometer (MODIS). This study presents a sensitivity analysis and preliminary algorithm to retrieve above-cloud AOD and liquid cloud optical depth (COD) for AAC cases from MODIS or similar sensors, for incorporation into a future version of the "Deep Blue" AOD data product. Detailed retrieval simulations suggest that these sensors should be able to determine AAC AOD with a typical level of uncertainty approximately 25-50 percent (with lower uncertainties for more strongly absorbing aerosol types) and COD with an uncertainty approximately10-20 percent, if an appropriate aerosol optical model is known beforehand. Errors are larger, particularly if the aerosols are only weakly absorbing, if the aerosol optical properties are not known, and the appropriate model to use must also be retrieved. Actual retrieval errors are also compared to uncertainty envelopes obtained through the optimal estimation (OE) technique; OE-based uncertainties are found to be generally reasonable for COD but larger than actual retrieval errors for AOD, due in part to difficulties in quantifying the degree of spectral correlation of forward model error. The algorithm is also applied to two MODIS scenes (one smoke and one dust) for which near-coincident NASA Ames Airborne Tracking Sun photometer (AATS) data were available to use as a ground truth AOD data source, and found to be in good agreement, demonstrating the validity of the technique with real observations.

  12. Establishment of a blue light damage model of human retinal pigment epithelial cells in vitro.

    Science.gov (United States)

    Su, G; Cai, S J; Gong, X; Wang, L L; Li, H H; Wang, L M

    2016-06-24

    To establish a blue-light damage model of human retinal pigment epithelium (RPE). Fourth-generation human RPE cells were randomly divided into two groups. In group A, cells were exposed to blue light (2000 ± 500 lux) for 0 (control), 3, 6, 9, and 12 h, and cell culture was stopped after 12 h. In group B, cells were exposed to blue light at the same intensity and time periods, but cell culture was stopped after 24 h. TdT-mediated dUTP nick-end labeling (TUNEL) assay was performed to determine the most suitable illuminating time with apoptotic index. Flow cytometry was used to determine apoptotic ratio of RPEs. In group A, the apoptotic index of cells that received 6, 9 and 12 h of blue light was higher than that of control. The apoptotic index of cells receiving 9 and 12 h was higher than that of 6 h (P = 0.000). In group B, the apoptotic index and RPE cell apoptosis ratio of cells exposed to 6, 9 and 12 h of blue light were higher than that of 3 h (P = 0.000); and cells receiving 9 and 12 h had higher values than that of 6 h. This study demonstrated that the best conditions to establish a blue light damage model of human retinal pigment epithelial cells in vitro are 2000 ± 500 lux light intensity for 6 h, with 24 h of cell culture post-exposure.

  13. Sensitivity to Ethephon Degreening Treatment Is Altered by Blue LED Light Irradiation in Mandarin Fruit.

    Science.gov (United States)

    Deng, Lili; Yuan, Ziyi; Xie, Jiao; Yao, Shixiang; Zeng, Kaifang

    2017-08-02

    Although citrus fruits are not climacteric, exogenous ethylene is widely used in the degreening treatment of citrus fruits. Irradiation with blue light-emitting diode (LED) light (450 nm) for 10 h can promote the formation of good coloration of ethephon-degreened fruit. This study evaluated the effect of blue LED light irradiation on the pigments contents of ethephon-degreened fruit and evaluated whether the blue LED light irradiation could influence the sensitivity of mandarin fruit to ethylene. The results indicated that blue light can accelerate the color change of ethephon-degreened fruit, accompanied by changes in plastid ultrastructure and chlorophyll and carotenoid contents. Ethephon-induced expressions of CitACS1, CitACO, CitETR1, CitEIN2, CitEIL1, and CitERF2 were enhanced by blue LED light irradiation, which increased the sensitivity to ethylene in ethephon-degreened fruits. These results indicate that blue LED light-induced changes in sensitivity to ethylene in mandarin fruit may be responsible for the improved coloration of ethephon-degreened mandarin fruits.

  14. Taurine reduces blue light-induced retinal neuronal cell apoptosis in vitro.

    Science.gov (United States)

    Dayang, Wu; Dongbo, Pang

    2018-02-27

    The massive uptake of organic compatible osmolytes is a self-protective response to multiple stressors. This study aimed to determine the protective effects of the osmolyte taurine against blue light-induced apoptosis in retinal neuronal cells in vitro. Real-time PCR was used to measure osmolyte transport. Radioimmunoassays were performed to measure osmolyte uptake. Cell Counting Kit-8 assays were conducted to measure cellular viability. Flow cytometry analysis was used to measure apoptosis. Compared with normotonic stress, hypertonic stress-induced uptake of osmolytes, including betaine, myoinositol, and taurine, into the retinal neuronal cells. Blue light increased osmolyte transporter mRNA expression together with osmolyte uptake. Furthermore, taurine significantly suppressed blue light-induced retinal neuronal cell apoptosis. The compatible osmolyte taurine may have an important role in cell resistance to blue light and cell survival.

  15. Monolithically Integrated Light Feedback Control Circuit for Blue/UV LED Smart Package

    NARCIS (Netherlands)

    Koladouz Esfahani, Z.; Tohidian, M.; van Zeijl, H.W.; Kolahdouz, Mohammadreza; Zhang, G.Q.

    2017-01-01

    Given the performance decay of high-power light-emitting diode (LED) chips over time and package condition changes, having a reliable output light for sensitive applications is a point of concern. In this study, a light feedback control circuit, including blue-selective photodiodes, for

  16. Blue lighting decreases the amount of food consumed in men, but not in women.

    Science.gov (United States)

    Cho, Sungeun; Han, Ashley; Taylor, Michael H; Huck, Alexandria C; Mishler, Amanda M; Mattal, Kyle L; Barker, Caleb A; Seo, Han-Seok

    2015-02-01

    Previous research has demonstrated that colors of lighting can modulate participants' motivation to consume the food placed under the lighting. This study was designed to determine whether the colors of lighting can affect the amount of food consumed, in addition to sensory perception of the food. The influence of lighting color was also compared between men and women. One-hundred twelve participants (62 men and 50 women) were asked to consume a breakfast meal (omelets and mini-pancakes) under one of three different lighting colors: white, yellow, and blue. During the test, hedonic impression of the food's appearance, willingness to eat, overall flavor intensity and overall impression of the food, and meal size (i.e., the amount of food consumed) were measured. Blue lighting decreased the hedonic impression of the food's appearance, but not the willingness to eat, compared to yellow and white lighting conditions. The blue lighting significantly decreased the amount consumed in men, but not in women, compared to yellow and white lighting conditions. Overall flavor intensity and overall impression of the food were not significantly different among the three lighting colors. In conclusion, this study provides empirical evidence that the color of lighting can modulate the meal size. In particular, blue lighting can decrease the amount of food eaten in men without reducing their acceptability of the food. Published by Elsevier Ltd.

  17. Blue lighting accelerates post-stress relaxation: Results of a preliminary study.

    Directory of Open Access Journals (Sweden)

    Jesus Minguillon

    Full Text Available Several authors have studied the influence of light on both human physiology and emotions. Blue light has been proved to reduce sleepiness by suppression of melatonin secretion and it is also present in many emotion-related studies. Most of these have a common lack of objective methodology since results and conclusions are based on subjective perception of emotions. The aim of this work was the objective assessment of the effect of blue lighting in post-stress relaxation, in comparison with white lighting, by means of bio-signals and standardized procedures. We conducted a study in which twelve healthy volunteers were stressed and then performed a relaxation session within a chromotherapy room with blue (test group or white (control group lighting. We conclude that the blue lighting accelerates the relaxation process after stress in comparison with conventional white lighting. The relaxation time decreased by approximately three-fold (1.1 vs. 3.5 minutes. We also observed a convergence time (3.5-5 minutes after which the advantage of blue lighting disappeared. This supports the relationship between color of light and stress, and the observations reported in previous works. These findings could be useful in clinical and educational environments, as well as in daily-life context and emerging technologies such as neuromarketing. However, our study must be extended to draw reliable conclusions and solid scientific evidence.

  18. Blue lighting accelerates post-stress relaxation: Results of a preliminary study.

    Science.gov (United States)

    Minguillon, Jesus; Lopez-Gordo, Miguel Angel; Renedo-Criado, Diego A; Sanchez-Carrion, Maria Jose; Pelayo, Francisco

    2017-01-01

    Several authors have studied the influence of light on both human physiology and emotions. Blue light has been proved to reduce sleepiness by suppression of melatonin secretion and it is also present in many emotion-related studies. Most of these have a common lack of objective methodology since results and conclusions are based on subjective perception of emotions. The aim of this work was the objective assessment of the effect of blue lighting in post-stress relaxation, in comparison with white lighting, by means of bio-signals and standardized procedures. We conducted a study in which twelve healthy volunteers were stressed and then performed a relaxation session within a chromotherapy room with blue (test group) or white (control group) lighting. We conclude that the blue lighting accelerates the relaxation process after stress in comparison with conventional white lighting. The relaxation time decreased by approximately three-fold (1.1 vs. 3.5 minutes). We also observed a convergence time (3.5-5 minutes) after which the advantage of blue lighting disappeared. This supports the relationship between color of light and stress, and the observations reported in previous works. These findings could be useful in clinical and educational environments, as well as in daily-life context and emerging technologies such as neuromarketing. However, our study must be extended to draw reliable conclusions and solid scientific evidence.

  19. HOT DUST OBSCURED GALAXIES WITH EXCESS BLUE LIGHT: DUAL AGN OR SINGLE AGN UNDER EXTREME CONDITIONS?

    Energy Technology Data Exchange (ETDEWEB)

    Assef, R. J.; Diaz-Santos, T. [Núcleo de Astronomía de la Facultad de Ingeniería, Universidad Diego Portales, Av. Ejército Libertador 441, Santiago (Chile); Walton, D. J.; Brightman, M. [Space Radiation Laboratory, California Institute of Technology, Pasadena, CA 91125 (United States); Stern, D.; Eisenhardt, P. R. M.; Tsai, C.-W. [Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Mail Stop 169-236, Pasadena, CA 91109 (United States); Alexander, D. [Department of Physics, Durham University, Durham DH1 3LE (United Kingdom); Bauer, F. [Departamento de Astronomía y Astrofísica, Pontificia Universidad Católica de Chile, Casilla 306, Santiago 22 (Chile); Blain, A. W. [Physics and Astronomy, University of Leicester, 1 University Road, Leicester LE1 7RH (United Kingdom); Finkelstein, S. L. [The University of Texas at Austin, 2515 Speedway, Stop C1400, Austin, TX 78712 (United States); Hickox, R. C. [Department of Physics and Astronomy, Dartmouth College, 6127 Wilder Laboratory, Hanover, NH 03755 (United States); Wu, J. W., E-mail: roberto.assef@mail.udp.cl [UCLA Astronomy, P.O. Box 951547, Los Angeles, CA 90095-1547 (United States)

    2016-03-10

    Hot dust-obscured galaxies (Hot DOGs) are a population of hyper-luminous infrared galaxies identified by the Wide-field Infrared Survey Explorer (WISE) mission from their very red mid-IR colors, and characterized by hot dust temperatures (T > 60 K). Several studies have shown clear evidence that the IR emission in these objects is powered by a highly dust-obscured active galactic nucleus (AGN) that shows close to Compton-thick absorption at X-ray wavelengths. Thanks to the high AGN obscuration, the host galaxy is easily observable, and has UV/optical colors usually consistent with those of a normal galaxy. Here we discuss a sub-population of eight Hot DOGs that show enhanced rest-frame UV/optical emission. We discuss three scenarios that might explain the excess UV emission: (i) unobscured light leaked from the AGN by reflection over the dust or by partial coverage of the accretion disk; (ii) a second unobscured AGN in the system; or (iii) a luminous young starburst. X-ray observations can help discriminate between these scenarios. We study in detail the blue excess Hot DOG WISE J020446.13–050640.8, which was serendipitously observed by Chandra/ACIS-I for 174.5 ks. The X-ray spectrum is consistent with a single, hyper-luminous, highly absorbed AGN, and is strongly inconsistent with the presence of a secondary unobscured AGN. Based on this, we argue that the excess blue emission in this object is most likely either due to reflection or a co-eval starburst. We favor the reflection scenario as the unobscured star formation rate needed to power the UV/optical emission would be ≳1000 M{sub ⊙} yr{sup −1}. Deep polarimetry observations could confirm the reflection hypothesis.

  20. The effect of nocturnal blue light exposure from light-emitting diodes on wakefulness and energy metabolism the following morning.

    Science.gov (United States)

    Kayaba, Momoko; Iwayama, Kaito; Ogata, Hitomi; Seya, Yumi; Kiyono, Ken; Satoh, Makoto; Tokuyama, Kumpei

    2014-09-01

    The control of sleep/wakefulness is associated with the regulation of energy metabolism. The present experiment was designed to assess the effect of nocturnal blue light exposure on the control of sleep/wakefulness and energy metabolism until next noon. In a balanced cross-over design, nine young male subjects sitting in a room-size metabolic chamber were exposed either to blue LEDs or to no light for 2 h in the evening. Wavelength of monochromatic LEDs was 465 nm and its intensity was 12.1 μW/cm(2). During sleep, sleep architecture and alpha and delta power of EEG were similar in the two experimental conditions. However, the following morning, when subjects were instructed to stay awake in a sitting position, duration judged as sleep at stages 1 and 2 was longer for subjects who received than for those who received no light exposure. Energy metabolism during sleep was not affected by evening blue light exposure, but the next morning energy expenditure, oxygen consumption, carbon dioxide production and the thermic effect of breakfast were significantly lower in subjects who received blue light exposure than in those who received no light exposure. Exposure to low intensity blue light in the evening, which does not affect sleep architecture and energy metabolism during sleep, elicits drowsiness and suppression of energy metabolism the following morning.

  1. Stress Reaction in Outer Segments of Photoreceptors after Blue Light Irradiation

    Science.gov (United States)

    Ader, Marius; Brunssen, Coy; Bramke, Silvia; Morawietz, Henning; Funk, Richard H. W.

    2013-01-01

    The retina is prone to oxidative stress from many factors which are also involved in the pathogenesis of degenerative diseases. In this study, we used the application of blue light as a physiological stress factor. The aim of this study was to identify the major source of intracellular ROS that mediates blue light-induced detrimental effects on cells which may lead to cytotoxicity. We hypothesized that outer segments are the major source of blue light induced ROS generation. In photoreceptors, nicotinamide adenine dinucleotide phosphate (NADPH) oxidase (Nox) enzymes and the recently found respiratory chain complexes may represent a major source for reactive oxygen species (ROS), beside mitochondria and chromophores. Therefore, we investigated this hypothesis and analysed the exact localization of the ROS source in photoreceptors in an organotypic culture system for mouse retinas. Whole eyeball cultures were irradiated with visible blue light (405 nm) with an output power of 1 mW/cm2. Blue light impingement lead to an increase of ROS production (detected by H2DCFDA in live retinal explants), which was particularly strong in the photoreceptor outer segments. Nox-2 and Nox-4 proteins are sources of ROS in blue light irradiated photoreceptors; the Nox inhibitor apocynin decreased ROS stimulated by blue light. Concomitantly, enzyme SOD-1, a member of the antioxidant defense system, indicator molecules of protein oxidation (CML) and lipid oxidation (MDA and 4-HNE) were also increased in the outer segments. Interestingly, outer segments showed a mitochondrial-like membrane potential which was demonstrated using two dyes (JC-1 and TMRE) normally exclusively associated with mitochondria. As in mitochondria, these dyes indicated a decrease of the membrane potential in hypoxic states or cell stress situations. The present study demonstrates that ROS generation and oxidative stress occurs directly in the outer segments of photoreceptors after blue light irradiation. PMID

  2. The Phototoxicity of Blue Light on the Functional Properties of the Retinal Pigment Epithelium

    Science.gov (United States)

    1989-05-01

    The phototoxic effect of blue light on isolated pigment epithelium will be investigated. The emphasis will be on functional changes rather than a...integrity of the barrier system and the transport system and the transport systems known to operate in the pigment epithelium. The effects of blue ... light on leucine transport across the isolated bovine retinal pigment epithelium (RPE) have been continued to determine if Vitamin E and melatonin

  3. Spectral effects of light-emitting diodes on plant growth and development: The importance of green and blue light

    Science.gov (United States)

    Cope, K. R.; Bugbee, B.

    2011-12-01

    Light-emitting diodes (LEDs) are an emerging technology for plant growth lighting. Due to their narrow spectral output, colored LEDs provide many options for studying the spectral effects of light on plants. Early on, efficient red LEDs were the primary focus of photobiological research; however, subsequent studies have shown that normal plant growth and development cannot be achieved under red light without blue light supplementation. More recent studies have shown that red and blue (RB) LEDs supplemented with green light increase plant dry mass. This is because green light transmits more effectively through the leaf canopy than red and blue light, thus illuminating lower plant leaves and increasing whole-plant photosynthesis. Red, green and blue (RGB) light can be provided by either a conventional white light source (such as fluorescent lights), a combination of RGB LEDs, or from recently developed white LEDs. White LEDs exceed the efficiency of fluorescent lights and have a comparable broad spectrum. As such, they have the potential to replace fluorescent lighting for growth-chamber-based crop production both on Earth and in space. Here we report the results of studies on the effects of three white LED types (warm, neutral and cool) on plant growth and development compared to combinations of RB and RGB LEDs. Plants were grown under two constant light intensities (200 and 500 μmol m-2 s-1). Temperature, environmental conditions and root-zone environment were uniformly maintained across treatments. Phytochrome photoequilbria and red/far-red ratios were similar among treatments and were comparable to conventional fluorescent lights. Blue light had a significant effect on both plant growth (dry mass gain) and development (dry mass partitioning). An increase in the absolute amount (μmol m-2 s-1) of blue light from 0-80 μmol m-2 s-1 resulted in a decrease in stem elongation, independent of the light intensity. However, an increase in the relative amount (%) of blue

  4. Rigorous modelling of light's intensity angular-profile in Abbe refractometers with absorbing homogeneous fluids

    International Nuclear Information System (INIS)

    García-Valenzuela, A; Contreras-Tello, H; Márquez-Islas, R; Sánchez-Pérez, C

    2013-01-01

    We derive an optical model for the light intensity distribution around the critical angle in a standard Abbe refractometer when used on absorbing homogenous fluids. The model is developed using rigorous electromagnetic optics. The obtained formula is very simple and can be used suitably in the analysis and design of optical sensors relying on Abbe type refractometry.

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

    Energy Technology Data Exchange (ETDEWEB)

    Stevens, John Colby [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). The Joint Center for Artificial Photosynthesis; Univ. of California, Berkeley, CA (United States). Dept. of Mechanical Engineering

    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.

  6. Light-absorbing carbon from prescribed and laboratory biomass burning and gasoline vehicle emissions

    Science.gov (United States)

    Carbonaceous aerosols are ubiquitous in the atmosphere and can directly affect Earth’s climate by absorbing and scattering incoming solar radiation. Both field and laboratory measurements have confirmed that biomass burning (BB) is an important primary source of light absor...

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

  8. Genetic separation of phototropism and blue light inhibition of stem elongation

    Science.gov (United States)

    Liscum, E.; Young, J. C.; Poff, K. L.; Hangarter, R. P.

    1992-01-01

    Blue light-induced regulation of cell elongation is a component of the signal response pathway for both phototropic curvature and inhibition of stem elongation in higher plants. To determine if blue light regulates cell elongation in these responses through shared or discrete pathways, phototropism and hypocotyl elongation were investigated in several blue light response mutants in Arabidopsis thaliana. Specifically, the blu mutants that lack blue light-dependent inhibition of hypocotyl elongation were found to exhibit a normal phototropic response. In contrast, a phototropic null mutant (JK218) and a mutant that has a 20- to 30-fold shift in the fluence dependence for first positive phototropism (JK224) showed normal inhibition of hypocotyl elongation in blue light. F1 progeny of crosses between the blu mutants and JK218 showed normal phototropism and inhibition of hypocotyl elongation, and approximately 1 in 16 F2 progeny were double mutants lacking both responses. Thus, blue light-dependent inhibition of hypocotyl elongation and phototropism operate through at least some genetically distinct components.

  9. A Dynamic Model for Prediction of Psoriasis Management by Blue Light Irradiation.

    Science.gov (United States)

    Félix Garza, Zandra C; Liebmann, Joerg; Born, Matthias; Hilbers, Peter A J; van Riel, Natal A W

    2017-01-01

    Clinical investigations prove that blue light irradiation reduces the severity of psoriasis vulgaris. Nevertheless, the mechanisms involved in the management of this condition remain poorly defined. Despite the encouraging results of the clinical studies, no clear guidelines are specified in the literature for the irradiation scheme regime of blue light-based therapy for psoriasis. We investigated the underlying mechanism of blue light irradiation of psoriatic skin, and tested the hypothesis that regulation of proliferation is a key process. We implemented a mechanistic model of cellular epidermal dynamics to analyze whether a temporary decrease of keratinocytes hyper-proliferation can explain the outcome of phototherapy with blue light. Our results suggest that the main effect of blue light on keratinocytes impacts the proliferative cells. They show that the decrease in the keratinocytes proliferative capacity is sufficient to induce a transient decrease in the severity of psoriasis. To study the impact of the therapeutic regime on the efficacy of psoriasis treatment, we performed simulations for different combinations of the treatment parameters, i.e., length of treatment, fluence (also referred to as dose), and intensity. These simulations indicate that high efficacy is achieved by regimes with long duration and high fluence levels, regardless of the chosen intensity. Our modeling approach constitutes a framework for testing diverse hypotheses on the underlying mechanism of blue light-based phototherapy, and for designing effective strategies for the treatment of psoriasis.

  10. Modulatory Effect of Monochromatic Blue Light on Heat Stress Response in Commercial Broilers.

    Science.gov (United States)

    Abdo, Safaa E; El-Kassas, Seham; El-Nahas, Abeer F; Mahmoud, Shawky

    2017-01-01

    In a novel approach, monochromatic blue light was used to investigate its modulatory effect on heat stress biomarkers in two commercial broiler strains (Ross 308 and Cobb 500). At 21 days old, birds were divided into four groups including one group housed in white light, a second group exposed to blue light, a 3rd group exposed to white light + heat stress, and a 4th group exposed to blue light + heat stress. Heat treatment at 33°C lasted for five h for four successive days. Exposure to blue light during heat stress reduced MDA concentration and enhanced SOD and CAT enzyme activities as well as modulated their gene expression. Blue light also reduced the degenerative changes that occurred in the liver tissue as a result of heat stress. It regulated, though variably, liver HSP70 , HSP90 , HSF1 , and HSF3 gene expression among Ross and Cobb chickens. Moreover, the Cobb strain showed better performance than Ross manifested by a significant reduction of rectal temperature in the case of H + B. Furthermore, a significant linear relationship was found between the lowered rectal temperature and the expression of all HSP genes. Generally, the performance of both strains by most assessed parameters under heat stress is improved when using blue light.

  11. Acridine orange exhibits photodamage in human bladder cancer cells under blue light exposure.

    Science.gov (United States)

    Lin, Yi-Chia; Lin, Ji-Fan; Tsai, Te-Fu; Chen, Hung-En; Chou, Kuang-Yu; Yang, Shan-Che; Tang, Ya-Ming; Hwang, Thomas I-Sheng

    2017-10-26

    Human bladder cancer (BC) cells exhibit a high basal level of autophagic activity with accumulation of acridine-orange(AO)-stained acidic vesicular organelles. The rapid AO relocalization was observed in treated BC cells under blue-light emission. To investigate the cytotoxic effects of AO on human BC cell lines under blue-light exposure, human immortalized uroepithelial (SV-Huc-1) and BC cell lines (5637 and T24) were treated with indicated concentrations of AO or blue-light exposure alone and in combination. The cell viability was then determined using WST-1, time-lapse imaging with a Cytosmart System and continuous quantification with a multi-mode image-based reader. Treatment of AO or blue-light exposure alone did not cause a significant loss of viability in BC cells. However, AO exhibited a dose-dependent increment of cytotoxicity toward BC cells under blue-light exposure. Furthermore, the tumor formation of BC cells with treatment was significantly reduced when evaluated in a mouse xenograft model. The photodamage caused by AO was nearly neglected in SV-Huc-1 cells, suggesting a differential effect of this treatment between cancer and normal cells. In summary, AO, as a photosensitizer, disrupts acidic organelles and induces cancer cell death in BC cells under blue-light irradiation. Our findings may serve as a novel therapeutic strategy against human BC.

  12. The blue light signal transduction pathway is involved in anthocyanin accumulation in 'Red Zaosu' pear.

    Science.gov (United States)

    Tao, Ruiyan; Bai, Songling; Ni, Junbei; Yang, Qinsong; Zhao, Yuan; Teng, Yuanwen

    2018-03-15

    A conserved blue light sensing and transduction pathway contributes to blue light-induced anthocyanin accumulation in the peel of red pear. Peel color is an economically important characteristic that influences the appearance quality of red pear, whose red color is due to anthocyanin accumulation. The process of coloration in the fruit peel is strongly influenced by light. However, how light quality influences color development remains unclear. In this study, we analyzed the effects of different light qualities on color development in the red pear 'Red Zaosu', a mutant of the hybrid cultivar 'Zaosu' of Pyrus pyrifolia and P. communis. The results showed that blue light increased anthocyanin accumulation after 72 h of light treatment, while red light had almost no effect. The expression of anthocyanin biosynthesis-related genes showed a similar trend to the anthocyanin accumulation. To clarify the mechanism of blue-light induced coloration, PpCRYs, PpCOP1 and PpHY5 genes were cloned. Gene expression analysis showed that their transcript abundance did not correlate with the expression of anthocyanin-related genes or anthocyanin content, but the yeast two-hybrid system revealed conserved physical interactions among these proteins. In addition, PpHY5 directly bound to the promoters of the anthocyanin biosynthesis genes PpCHS, PpDFR, PpANS and PpMYB10, and activated the transcription of PpCHS in a Nicotiana benthamiana-based dual-luciferase assay. In summary, our results preliminarily revealed that the conserved blue light signal transduction module CRY-COP1-HY5 contributed to the anthocyanin biosynthesis induced by blue light in red pear. However, our results did not provide evidence for why red light had no effect on anthocyanin accumulation, which needs further study.

  13. A CRY-BIC negative-feedback circuitry regulating blue light sensitivity of Arabidopsis.

    Science.gov (United States)

    Wang, Xu; Wang, Qin; Han, Yun-Jeong; Liu, Qing; Gu, Lianfeng; Yang, Zhaohe; Su, Jun; Liu, Bobin; Zuo, Zecheng; He, Wenjin; Wang, Jian; Liu, Bin; Matsui, Minami; Kim, Jeong-Il; Oka, Yoshito; Lin, Chentao

    2017-11-01

    Cryptochromes are blue light receptors that regulate various light responses in plants. Arabidopsis cryptochrome 1 (CRY1) and cryptochrome 2 (CRY2) mediate blue light inhibition of hypocotyl elongation and long-day (LD) promotion of floral initiation. It has been reported recently that two negative regulators of Arabidopsis cryptochromes, Blue light Inhibitors of Cryptochromes 1 and 2 (BIC1 and BIC2), inhibit cryptochrome function by blocking blue light-dependent cryptochrome dimerization. However, it remained unclear how cryptochromes regulate the BIC gene activity. Here we show that cryptochromes mediate light activation of transcription of the BIC genes, by suppressing the activity of CONSTITUTIVE PHOTOMORPHOGENIC 1 (COP1), resulting in activation of the transcription activator ELONGATED HYPOCOTYL 5 (HY5) that is associated with chromatins of the BIC promoters. These results demonstrate a CRY-BIC negative-feedback circuitry that regulates the activity of each other. Surprisingly, phytochromes also mediate light activation of BIC transcription, suggesting a novel photoreceptor co-action mechanism to sustain blue light sensitivity of plants under the broad spectra of solar radiation in nature. © 2017 The Authors The Plant Journal © 2017 John Wiley & Sons Ltd.

  14. Therapeutic effect of turquoise versus blue light with equal irradiance in preterm infants with jaundice

    DEFF Research Database (Denmark)

    Ebbesen, Finn; Madsen, Poul; Støvring, Søren

    2007-01-01

    AIM: To compare the efficiency of turquoise light with that of TL52 blue in treatment of preterm infants with jaundice at the same level of body irradiance. METHODS: Infants with gestational age 28-37 weeks and non-haemolytic hyperbilirubinemia were treated for 24 h with either turquoise light......,Z-bilirubin and lumirubin, in infants under turquoise light. This suggests, given equal irradiances, that light in the turquoise spectral range is preferable to the TL52 blue in treatment of newborn jaundiced infants....

  15. Preliminary evidence that both blue and red light can induce alertness at night

    Directory of Open Access Journals (Sweden)

    Plitnick Barbara

    2009-08-01

    Full Text Available Abstract Background A variety of studies have demonstrated that retinal light exposure can increase alertness at night. It is now well accepted that the circadian system is maximally sensitive to short-wavelength (blue light and is quite insensitive to long-wavelength (red light. Retinal exposures to blue light at night have been recently shown to impact alertness, implicating participation by the circadian system. The present experiment was conducted to look at the impact of both blue and red light at two different levels on nocturnal alertness. Visually effective but moderate levels of red light are ineffective for stimulating the circadian system. If it were shown that a moderate level of red light impacts alertness, it would have had to occur via a pathway other than through the circadian system. Methods Fourteen subjects participated in a within-subject two-night study, where each participant was exposed to four experimental lighting conditions. Each night each subject was presented a high (40 lx at the cornea and a low (10 lx at the cornea diffuse light exposure condition of the same spectrum (blue, λmax = 470 nm, or red, λmax = 630 nm. The presentation order of the light levels was counterbalanced across sessions for a given subject; light spectra were counterbalanced across subjects within sessions. Prior to each lighting condition, subjects remained in the dark ( Results Exposures to red and to blue light resulted in increased beta and reduced alpha power relative to preceding dark conditions. Exposures to high, but not low, levels of red and of blue light significantly increased heart rate relative to the dark condition. Performance and sleepiness ratings were not strongly affected by the lighting conditions. Only the higher level of blue light resulted in a reduction in melatonin levels relative to the other lighting conditions. Conclusion These results support previous findings that alertness may be mediated by the circadian system

  16. Early Birds by Light at Night: Effects of Light Color and Intensity on Daily Activity Patterns in Blue Tits

    NARCIS (Netherlands)

    de Jong, Maaike; Caro, Samuel P.; Gienapp, Phillip; Spoelstra, Kamiel; Visser, Marcel E.

    2017-01-01

    Artificial light at night disturbs the daily rhythms of many organisms. To what extent this disturbance depends on the intensity and spectral composition of light remain obscure. Here, we measured daily activity patterns of captive blue tits (Cyanistes caeruleus) exposed to similar intensities of

  17. The effects of blue-enriched light treatment compared to standard light treatment in seasonal affective disorder

    NARCIS (Netherlands)

    Gordijn, M. C. M.; 't Mannetje, D.; Meesters, Y.

    Background: One of the most frequently investigated hypotheses of the pathophysiology underlying Seasonal Affective Disorder (SAD) is a disturbance of circadian rhythms. Since the circadian system as well as other non-visual effects is especially sensitive to blue light, a new light therapy device

  18. Improving spinach, radish, and lettuce growth under red light-emitting diodes (LEDs) with blue light supplementation

    Science.gov (United States)

    Yorio, N. C.; Goins, G. D.; Kagie, H. R.; Wheeler, R. M.; Sager, J. C.

    2001-01-01

    Radish (Raphanus sativus L. cv. Cherriette), lettuce (Lactuca sativa L. cv. Waldmann's Green), and spinach (Spinacea oleracea L. cv. Nordic IV) plants were grown under 660-nm red light-emitting diodes (LEDs) and were compared at equal photosynthetic photon flux (PPF) with either plants grown under cool-white fluorescent lamps (CWF) or red LEDs supplemented with 10% (30 micromoles m-2 s-1) blue light (400-500 nm) from blue fluorescent (BF) lamps. At 21 days after planting (DAP), leaf photosynthetic rates and stomatal conductance were greater for plants grown under CWF light than for those grown under red LEDs, with or without supplemental blue light. At harvest (21 DAP), total dry-weight accumulation was significantly lower for all species tested when grown under red LEDs alone than when grown under CWF light or red LEDs + 10% BF light. Moreover, total dry weight for radish and spinach was significantly lower under red LEDs + 10% BF than under CWF light, suggesting that addition of blue light to the red LEDs was still insufficient for achieving maximal growth for these crops.

  19. Mechanism of rapid suppression of cell expansion in cucumber hypocotyls after blue-light irradiation

    Science.gov (United States)

    Cosgrove, D. J.

    1988-01-01

    Rapid suppression of hypocotyl elongation by blue light in cucumber (Cucumis sativus L.) was studied to examine possible hydraulic and wall changes responsible for diminished growth. Cell-sap osmotic pressure, measured by vapor-pressure osmometry, was not decreased by blue light; turgor pressure, measured by the pressure-probe technique, remained constant during the growth inhibition; and stem hydraulic conductance, measured by dynamic and static methods, was likewise unaffected by blue light. Wall yielding properties were assessed by the pressure-block technique for in-vivo stress relaxation. Blue light reduced the initial rate of relaxation by 77%, but had little effect on the final amount of relaxation. The results demonstrate that blue irradiation acts to decrease the wall yielding coefficient, but not the yield threshold. Stress-strain (Instron) analysis showed that irradiation of the seedlings had little effect on the mechanical extensibilities of the isolated wall. The results indicate that blue light can reduce cell-wall loosening without affecting bulk viscoelastic properties, and indicate a chemorheological mechanism of cell-wall expansion.

  20. Broadband plasmonic perfect light absorber in the visible spectrum for solar cell applications

    Science.gov (United States)

    Mudachathi, Renilkumar; Tanaka, Takuo

    2018-03-01

    The coupling of electromagnetic waves with subwavelength metal structures results in the perfect light absorption and has been extensively explored in the recent years for many possible applications like photovoltaics, sensing, photodetectors, emitters and camouflaging systems to name a few. Herein we present the design and fabrication of a broadband plasmonic light absorber using aluminum as functional material for operation in the visible frequency range. The metal structures can be tuned in size to manipulate the plasmonic resonance; thereby light absorption at any desired wavelengths could be realized. Thus the broadband light absorber in the visible spectrum is designed using metal structures of different sizes supporting non-overlapping individual resonances at regular intervals of wavelengths. The metal structures of different sizes are grouped in to a single unit cell and the absorber is fabricated by periodically arranging these unit cells in a square lattice. Light absorption of more than 90% for over a broad wavelength range of 200 nm from 425 nm to 650 nm in the visible spectrum is demonstrated.

  1. Source attribution of light-absorbing impurities in seasonal snow across northern China

    Science.gov (United States)

    Zhang, R.; Hegg, D. A.; Huang, J.; Fu, Q.

    2013-01-01

    Seasonal snow samples obtained at 46 sites in 6 provinces of China in January and February 2010 were analyzed for a suite of chemical species and these data are combined with previously determined concentrations of light-absorbing impurities (LAI), including all particles that absorb light in the 650-700 nm wavelength interval. The LAI, together with 14 other analytes, are used as input to a positive matrix factorization (PMF) receptor model to explore the sources of the LAI in the snow. The PMF analysis for the LAI sources is augmented with backward trajectory cluster analysis and the geographic locations of major source areas for the three source types. The two analyses are consistent and indicate that three factors/sources were responsible for the measured snow light absorption: a soil dust source, an industrial pollution source, and a biomass and biofuels burning source. Soil dust was the main source of the LAI, accounting for ~ 53% of the LAI on average.

  2. Source attribution of insoluble light-absorbing particles in seasonal snow across northern China

    Science.gov (United States)

    Zhang, R.; Hegg, D. A.; Huang, J.; Fu, Q.

    2013-06-01

    Seasonal snow samples obtained at 46 sites in 6 provinces of China in January and February 2010 were analyzed for a suite of chemical species and these data are combined with previously determined concentrations of insoluble light-absorbing particles (ILAP), including all particles that absorb light in the 650-700 nm wavelength interval. The ILAP, together with 14 other analytes, are used as input to a positive matrix factorization (PMF) receptor model to explore the sources of ILAP in the snow. The PMF analysis for ILAP sources is augmented with backward trajectory cluster analysis and the geographic locations of major source areas for the three source types. The two analyses are consistent and indicate that three factors/sources were responsible for the measured light absorption of snow: a soil dust source, an industrial pollution source, and a biomass and / or biofuel burning source. Soil dust was the main source of the ILAP, accounting for ~53% of ILAP on average.

  3. Blue-Light Hazard From Gas Metal Arc Welding of Aluminum Alloys.

    Science.gov (United States)

    Nakashima, Hitoshi; Takahashi, Jyunya; Fujii, Nobuyuki; Okuno, Tsutomu

    2017-10-01

    The objective was to quantify the blue-light hazard from gas metal arc welding (GMAW) of aluminum alloys. The exposure level is expected to depend on the welding conditions. Therefore, it is important to identify the blue-light hazard under various welding conditions. We experimentally conducted GMAW of aluminum alloys under various welding conditions and measured the spectral radiance of the arcs. The effective blue-light radiance, which the American Conference of Governmental Industrial Hygienists has defined to quantify the exposure level of blue light, was calculated from the measured spectral radiance. The maximum acceptable exposure duration per 10000 s for this effective blue-light radiance was calculated. The effective blue-light radiance measured in this study was in the range of 2.9-20.0 W cm-2·sr. The corresponding maximum acceptable exposure duration per 10000 s was only 5.0-34 s, so it is hazardous to view the welding arc. The effective blue-light radiance was higher at higher welding currents than at lower welding currents, when pulsed welding currents were used rather than steady welding currents, and when magnesium was included in the welding materials. It is very hazardous to view the arcs in GMAW of aluminum alloys. Welders and their helpers should use appropriate eye protection in arc-welding operations. They should also avoid direct light exposure when starting an arc-welding operation. © The Author 2017. Published by Oxford University Press on behalf of the British Occupational Hygiene Society.

  4. Morning and Evening Blue-Enriched Light Exposure Alters Metabolic Function in Normal Weight Adults

    Science.gov (United States)

    Cheung, Ivy N.; Zee, Phyllis C.; Shalman, Dov; Malkani, Roneil G.; Kang, Joseph; Reid, Kathryn J.

    2016-01-01

    Increasing evidence points to associations between light-dark exposure patterns, feeding behavior, and metabolism. This study aimed to determine the acute effects of 3 hours of morning versus evening blue-enriched light exposure compared to dim light on hunger, metabolic function, and physiological arousal. Nineteen healthy adults completed this 4-day inpatient protocol under dim light conditions (morning group) or 10.5 hours after wake (n = 10; evening group). All participants remained in dim light on Day 2 to serve as their baseline. Subjective hunger and sleepiness scales were collected hourly. Blood was sampled at 30-minute intervals for 4 hours in association with the light exposure period for glucose, insulin, cortisol, leptin, and ghrelin. Homeostatic model assessment of insulin resistance (HOMA-IR) and area under the curve (AUC) for insulin, glucose, HOMA-IR and cortisol were calculated. Comparisons relative to baseline were done using t-tests and repeated measures ANOVAs. In both the morning and evening groups, insulin total area, HOMA-IR, and HOMA-IR AUC were increased and subjective sleepiness was reduced with blue-enriched light compared to dim light. The evening group, but not the morning group, had significantly higher glucose peak value during blue-enriched light exposure compared to dim light. There were no other significant differences between the morning or the evening groups in response to blue-enriched light exposure. Blue-enriched light exposure acutely alters glucose metabolism and sleepiness, however the mechanisms behind this relationship and its impacts on hunger and appetite regulation remain unclear. These results provide further support for a role of environmental light exposure in the regulation of metabolism. PMID:27191727

  5. A novel blue-light phototropic response is revealed in roots of Arabidopsis thaliana in microgravity.

    Science.gov (United States)

    Vandenbrink, Joshua P; Herranz, Raul; Medina, F Javier; Edelmann, Richard E; Kiss, John Z

    2016-12-01

    Blue-light positive phototropism in roots is masked by gravity and revealed in conditions of microgravity. In addition, the magnitude of red-light positive phototropic curvature is correlated to the magnitude of gravity. Due to their sessile nature, plants utilize environmental cues to grow and respond to their surroundings. Two of these cues, light and gravity, play a substantial role in plant orientation and directed growth movements (tropisms). However, very little is currently known about the interaction between light- (phototropic) and gravity (gravitropic)-mediated growth responses. Utilizing the European Modular Cultivation System on board the International Space Station, we investigated the interaction between phototropic and gravitropic responses in three Arabidopsis thaliana genotypes, Landsberg wild type, as well as mutants of phytochrome A and phytochrome B. Onboard centrifuges were used to create a fractional gravity gradient ranging from reduced gravity up to 1g. A novel positive blue-light phototropic response of roots was observed during conditions of microgravity, and this response was attenuated at 0.1g. In addition, a red-light pretreatment of plants enhanced the magnitude of positive phototropic curvature of roots in response to blue illumination. In addition, a positive phototropic response of roots was observed when exposed to red light, and a decrease in response was gradual and correlated with the increase in gravity. The positive red-light phototropic curvature of hypocotyls when exposed to red light was also confirmed. Both red-light and blue-light phototropic responses were also shown to be affected by directional light intensity. To our knowledge, this is the first characterization of a positive blue-light phototropic response in Arabidopsis roots, as well as the first description of the relationship between these phototropic responses in fractional or reduced gravities.

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

  8. Early Birds by Light at Night: Effects of Light Color and Intensity on Daily Activity Patterns in Blue Tits.

    Science.gov (United States)

    de Jong, Maaike; Caro, Samuel P; Gienapp, Phillip; Spoelstra, Kamiel; Visser, Marcel E

    2017-08-01

    Artificial light at night disturbs the daily rhythms of many organisms. To what extent this disturbance depends on the intensity and spectral composition of light remain obscure. Here, we measured daily activity patterns of captive blue tits ( Cyanistes caeruleus) exposed to similar intensities of green, red, or white light at night. Birds advanced their onset of activity in the morning under all light colors but more under red and white light than under green light. Offset of activity was slightly delayed in all light colors. The total activity over a 24-h period did not change but birds moved a part of their daily activity into the night. Since the effect of red and white lights are comparable, we tested the influence of light intensity in a follow-up experiment, where we compared the activity of the birds under different intensities of green and white light only. While in the higher range of intensities, the effects of white and green light were comparable; at lower intensities, green light had a less disturbing effect as compared with white light on daily rhythms in blue tits. Our results show that the extent of this disturbance can be mitigated by modulating the spectral characteristics and intensity of outdoor lighting, which is now feasible through the use of LED lighting.

  9. Characterization of an Optical Device with an Array of Blue Light Emitting Diodes LEDS for Treatment of Neonatal Jaundice.

    Science.gov (United States)

    Sebbe, Priscilla Fróes; Villaverde, Antonio G. J. Balbin; Nicolau, Renata Amadei; Barbosa, Ana Maria; Veissid, Nelson

    2008-04-01

    Phototherapy is a treatment that consists in irradiating a patient with light of high intensity, which promotes beneficial photochemical transformations in the irradiated area. The phototherapy for neonates is applied to break down the bilirubin, an organic pigment that is a sub product of the erythrocytes degradation, and to increase its excretion by the organism. Neonates should be irradiated with light of wavelength that the bilirubin can absorb, and with spectral irradiances between 4 and 16 μW/cm2/nm. The efficiency of the treatment depends on the irradiance and the area of the body that is irradiated. A convenient source of light for treatment of neonatal jaundice is the blue Light Emitter Diode (LED), emitting in the range of 400 to 500 nm, with power of the order of 10-150 mW. Some of the advantages for using LEDS are: low cost, operating long lifetime (over 100,000 hours), narrow emission linewith, low voltage power supply requirement and low heating. The aim of this work was to build and characterize a device for phototherapy treatment of neonatal jaundice. This consists of a blanket with 88 blue LEDs (emission peak at 472 nm), arranged in an 8×11 matrix, all connected in parallel and powered by a 5V-2A power supply. The device was characterized by using a spectroradiometer USB2000 (Ocean Optics Inc, USA), with a sensitivity range of 339-1019 nm. For determination of light spatial uniformity was used a calibrated photovoltaic sensor for measuring light intensity and mapping of the light intensity spatial distribution. Results indicate that our device shows a uniform spatial distribution for distances from the blanket larger than 10 cm, with a maximum of irradiance at such a distance. This device presenting a large and uniform area of irradiation, efficient wavelength emission and high irradiance seems to be promising for neonates' phototherapy treatment.

  10. Enhanced light emission in blue light-emitting diodes by multiple Mie scattering from embedded silica nanosphere stacking layers.

    Science.gov (United States)

    Park, Young Jae; Kang, Ji Hye; Kim, Hee Yun; Lysak, Volodymyr V; Chandramohan, S; Ryu, Jae Hyoung; Kim, Hyun Kyu; Han, Nam; Jeong, Hyun; Jeong, Mun Seok; Hong, Chang-Hee

    2011-11-07

    We demonstrate enhanced light emission in blue light-emitting diodes (LEDs) by multiple Mie scattering from embedded silica nanosphere stacking layers (SNSL). A honeycomb cone structure is introduced in the GaN epilayer to confine a maximum number of silica nanospheres (SNs). We found that the light is predominantly directed vertically by scattering and geometrical effect in SNSL embedded LEDs. Consequently, the light output power is enhanced by 2.7 times, which we attribute to the improvement in light extraction efficiency due to the multiple Mie scattering of light from the embedded SNSL. The experimental results are verified by simulation using finite difference time domain method (FDTD).

  11. Influence of blue light spectrum filter on short-wavelength and standard automated perimetries.

    Science.gov (United States)

    Castro, Leonardo Cunha; de Souza, Carlos Eduardo Barbosa; Soriano, Eduardo Sone; Melo, Luiz Alberto Soares; Paranhos, Augusto

    2006-01-01

    To evaluate the influence of a blue light spectrum filter (BLSF), similar in light spectrum transmittance to the intraocular lens Acrysof Natural, on standard automated perimetry (SAP) and short-wavelength automated perimetry (SWAP). Twenty young individuals (automated perimetry (SAP) and short-wavelength automated perimetry (SWAP) with and without a blue light spectrum filter. All patients had intraocular pressure lower than 21 mmHg, normal fundus biomicroscopy, and no crystalline lens opacity. Foveal threshold (FT), mean deviation (MD), and pattern standard deviation (PSD) indexes obtained from the visual field tests and the difference caused by eccentricity in short-wavelength automated perimetry examinations were analyzed using paired t test. Interindividual variability (standard deviation) was calculated using Pitman's test for correlated samples. Statistically significant reductions in the mean deviation (p automated perimetry with the use of the blue light spectrum filter in comparison to short-wavelength automated perimetry without the use of the blue light spectrum filter were observed, but not in standard automated perimetry exams. No other parameters showed statistically significant differences in the short-wavelength automated perimetry and standard automated perimetry tests. Interindividual standard deviation of the test points in the short-wavelength automated perimetry exams increased with eccentricity both with and without the use of the blue light spectrum filter, as sensitivity for inferior and superior hemifields (inferior hemifield minus superior hemifield), but no statistically significant difference in the variability when comparing the use or not of the blue light spectrum filter was noted. When comparing only the four most inferior points and the four most superior points, the inferior-superior difference increases in both situations - without and with the use of the blue light spectrum filter. The difference between without and with the use

  12. Absence of red-light enhancement of phototropism in pea seedlings at limiting irradiances of blue light

    International Nuclear Information System (INIS)

    Britz, S.J.; Carroll, L.J. II

    1993-01-01

    The kinetics of phototropism were determined from infrared video recordings of third internodes of intact 7 d etiolated pea seedlings (Pisum sativum L. cv Alcan) exposed to continuous, unilateral blue light (460 nm). Small but significant curvatures (ca. 1–2°) were observed after a 2 h stimulation at 0.8 pmol m -2 s -1 . Both latency (i.e., lag time) and rate of curvature were dependent on irradiance between 0.8 and 80 pmol m -2 s -1 . Maximum rates of curvature at the highest irradiance of blue light were 74% greater in seedlings that received 2 min red light (270 J m -2 ) 20 h earlier, but latency was unaffected. An irradiance-response curve for curvature at 2 h was obtained with unilateral, broad-spectrum blue light between 4 and 90,000 pmol m -2 s -1 . Maximum tropistic response in dark-grown seedlings (ca. 25°) occurred between 30 and 1000 pmol m -2 s -1 . Peak response for red light-treated seedlings (ca. 55°) was obtained at 1000 pmol m -2 s -1 . Above this irradiance, phototropism declined by 12–15° for both red-treated and dark-grown plants. Red light did not significantly stimulate phototropism at lower, limiting irradiances of blue light. The data do not support the hypothesis that phytochrome affects the amount or activity of a photoreceptor for phototropism

  13. The blue light-induced interaction of cryptochrome 1 with COP1 requires SPA proteins during Arabidopsis light signaling.

    Science.gov (United States)

    Holtkotte, Xu; Ponnu, Jathish; Ahmad, Margaret; Hoecker, Ute

    2017-10-01

    Plants constantly adjust their growth, development and metabolism to the ambient light environment. Blue light is sensed by the Arabidopsis photoreceptors CRY1 and CRY2 which subsequently initiate light signal transduction by repressing the COP1/SPA E3 ubiquitin ligase. While the interaction between cryptochromes and SPA is blue light-dependent, it was proposed that CRY1 interacts with COP1 constitutively, i.e. also in darkness. Here, our in vivo co-immunoprecipitation experiments suggest that CRY1 and CRY2 form a complex with COP1 only after seedlings were exposed to blue light. No association between COP1 and CRY1 or CRY2 was observed in dark-grown seedlings. Thus, our results suggest that cryptochromes bind the COP1/SPA complex after photoactivation by blue light. In a spa quadruple mutant that is devoid of all four SPA proteins, CRY1 and COP1 did not interact in vivo, neither in dark-grown nor in blue light-grown seedlings. Hence, SPA proteins are required for the high-affinity interaction between CRY1 and COP1 in blue light. Yeast three-hybrid experiments also show that SPA1 enhances the CRY1-COP1 interaction. The coiled-coil domain of SPA1 which is responsible for COP1-binding was necessary to mediate a CRY1-SPA1 interaction in vivo, implying that-in turn-COP1 may be necessary for a CRY1-SPA1 complex formation. Hence, SPA1 and COP1 may act cooperatively in recognizing and binding photoactivated CRY1. In contrast, the blue light-induced association between CRY2 and COP1 was not dependent on SPA proteins in vivo. Similarly, ΔCC-SPA1 interacted with CRY2, though with a much lower affinity than wild-type SPA1. In total, our results demonstrate that CRY1 and CRY2 strongly differ in their blue light-induced interaction with the COP1/SPA complex.

  14. Blue light requirements for crop plants used in bioregenerative life support systems.

    Science.gov (United States)

    Yorio, N C; Wheeler, R M; Goins, G D; Sanwo-Lewandowski, M M; Mackowiak, C L; Brown, C S; Sager, J C; Stutte, G W

    1998-01-01

    As part of NASA's Advanced Life Support Program, the Breadboard Project at Kennedy Space Center is investigating the feasibility of using crop plants in bioregenerative life support systems (BLSS) for long-duration space missions. Several types of electric lamps have been tested to provide radiant energy for plants in a BLSS. These lamps vary greatly in terms of spectral quality resulting in differences in growth and morphology of the plants tested. Broad spectrum or "white" light sources (e.g., metal halide and fluorescent lamps) provide an adequate spectrum for normal growth and morphology; however, they are not as electrically efficient as are low-pressure sodium (LPS) or high-pressure sodium (HPS) lamps. Although LPS and HPS, as well as the newly tested red light-emitting diodes (LEDs), have good photosynthetically active radiation (PAR) efficiencies, they are deficient in blue light. Results with several of the crops tested for BLSS (wheat, potato, soybean, lettuce, and radish) have shown a minimum amount of blue light (approximately 30 micromoles m-2 s-1) is necessary for normal growth and development. For example, the lack of sufficient blue light in these lamps has resulted in increased stem elongation and significant reductions in photosynthesis and yield. To avoid problems with blue-deficient lamps and maximize yield, sufficient intensity of HPS or blue light supplementation with red LEDs or LPS lamps is required to meet spectral requirements of crops for BLSS.

  15. The effect of blue light on stomatal oscillations and leaf turgor pressure in banana leaves.

    Science.gov (United States)

    Zait, Yotam; Shapira, Or; Schwartz, Amnon

    2017-07-01

    Stomatal oscillations are cyclic opening and closing of stomata, presumed to initiate from hydraulic mismatch between leaf water supply and transpiration rate. To test this assumption, mismatches between water supply and transpiration were induced using manipulations of vapour pressure deficit (VPD) and light spectrum in banana (Musa acuminata). Simultaneous measurements of gas exchange with changes in leaf turgor pressure were used to describe the hydraulic mismatches. An increase of VPD above a certain threshold caused stomatal oscillations with variable amplitudes. Oscillations in leaf turgor pressure were synchronized with stomatal oscillations and balanced only when transpiration equaled water supply. Surprisingly, changing the light spectrum from red and blue to red alone at constant VPD also induced stomatal oscillations - while the addition of blue (10%) to red light only ended oscillations. Blue light is known to induce stomatal opening and thus should increase the hydraulic mismatch, reduce the VPD threshold for oscillations and increase the oscillation amplitude. Unexpectedly, blue light reduced oscillation amplitude, increased VPD threshold and reduced turgor pressure loss. These results suggest that additionally, to the known effect of blue light on the hydroactive opening response of stomata, it can also effect stomatal movement by increased xylem-epidermis water supply. © 2017 John Wiley & Sons Ltd.

  16. Commercial preslaughter blue light ambience for controlling broiler stress and meat qualities

    Directory of Open Access Journals (Sweden)

    Claudia Freitas Barbosa

    2013-10-01

    Full Text Available The objective of this work was to study the effect of blue light diffuser on the broiler stress control by measuring the occurrence of PSE meat just before slaughtering. Birds were divided into the following two groups before slaughter at the point of being hung on shackles: broiler group under low intensity blue light ambience (475, 17-20 lx and control group under white light (550-650nm, 321-332 lx. Birds' stressful conditions were measured by the occurrence of PSE meat. Breast fillets were classified as PSE meat based on pH ( 53.0. The fillet samples in the control group had the following characteristics: pHu=5.77, L* = 54.26 and b*= 6.27. The fillet samples from birds under blue light ambience had the following characteristics: pHu=5.81, L* = 52.86 and b* = 5.22 (p < 0.05. These results revealed that the treatment of blue light ambience just before slaughtering contributed to the alleviation of ante mortem stress of the birds, which was observed by a 14% decrease in the occurrence of PSE meat. Exposure to blue light just before slaughtering was shown to have potential to be used in modern slaughterhouses to offer a comfortable atmosphere, thereby maintaining breast meat quality.

  17. Regulation of ascorbic acid metabolism by blue LED light irradiation in citrus juice sacs.

    Science.gov (United States)

    Zhang, Lancui; Ma, Gang; Yamawaki, Kazuki; Ikoma, Yoshinori; Matsumoto, Hikaru; Yoshioka, Terutaka; Ohta, Satoshi; Kato, Masaya

    2015-04-01

    In the present study, the effects of red and blue LED lights on the accumulation of ascorbic acid (AsA) were investigated in the juice sacs of three citrus varieties, Satsuma mandarin, Valencia orange, and Lisbon lemon. The results showed that the blue LED light treatment effectively increased the AsA content in the juice sacs of the three citrus varieties, whereas the red LED light treatment did not. By increasing the blue LED light intensity, the juice sacs of the three citrus varieties accumulated more AsA. Moreover, continuous irradiation with blue LED light was more effective than pulsed irradiation for increasing the AsA content in the juice sacs of the three citrus varieties. Gene expression results showed that the modulation of AsA accumulation by blue LED light was highly regulated at the transcription level. The up-regulation of AsA biosynthetic genes (CitVTC1, CitVTC2, CitVTC4, and CitGLDH), AsA regeneration genes (CitMDAR1, CitMDAR2, and CitDHAR) and two GSH-producing genes (CitGR and CitchGR) contributed to these increases in the AsA content in the three citrus varieties. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

  1. Blue Light Rescues Mice from Potentially Fatal Pseudomonas aeruginosa Burn Infection: Efficacy, Safety, and Mechanism of Action

    Science.gov (United States)

    Dai, Tianhong; Gupta, Asheesh; Huang, Ying-Ying; Yin, Rui; Murray, Clinton K.; Vrahas, Mark S.; Sherwood, Margaret E.; Tegos, George P.

    2013-01-01

    Blue light has attracted increasing attention due to its intrinsic antimicrobial effect without the addition of exogenous photosensitizers. However, the use of blue light for wound infections has not been established yet. In this study, we demonstrated the efficacy of blue light at 415 nm for the treatment of acute, potentially lethal Pseudomonas aeruginosa burn infections in mice. Our in vitro studies demonstrated that the inactivation rate of P. aeruginosa cells by blue light was approximately 35-fold higher than that of keratinocytes (P = 0.0014). Transmission electron microscopy revealed blue light-mediated intracellular damage to P. aeruginosa cells. Fluorescence spectroscopy suggested that coproporphyrin III and/or uroporphyrin III are possibly the intracellular photosensitive chromophores associated with the blue light inactivation of P. aeruginosa. In vivo studies using an in vivo bioluminescence imaging technique and an area-under-the-bioluminescence-time-curve (AUBC) analysis showed that a single exposure of blue light at 55.8 J/cm2, applied 30 min after bacterial inoculation to the infected mouse burns, reduced the AUBC by approximately 100-fold in comparison with untreated and infected mouse burns (P blue light at the effective antimicrobial dose. Survival analyses revealed that blue light increased the survival rate of the infected mice from 18.2% to 100% (P blue light therapy might offer an effective and safe alternative to conventional antimicrobial therapy for P. aeruginosa burn infections. PMID:23262998

  2. The involvement of ATF4 and S-opsin in retinal photoreceptor cell damage induced by blue LED light.

    Science.gov (United States)

    Ooe, Emi; Tsuruma, Kazuhiro; Kuse, Yoshiki; Kobayashi, Saori; Shimazawa, Masamitsu; Hara, Hideaki

    2017-01-01

    Blue light is a high-energy emitting light with a short wavelength in the visible light spectrum. Blue light induces photoreceptor apoptosis and causes age-related macular degeneration or retinitis pigmentosa. In the present study, we investigated the roles of endoplasmic reticulum (ER) stress induced by blue light-emitting diode (LED) light exposure in murine photoreceptor cells. The murine photoreceptor cell line was incubated and exposed to blue LED light (464 nm blue LED light, 450 lx, 3 to 24 h). The expression of the factors involved in the unfolded protein response pathway was examined using quantitative real-time reverse transcription (RT)-PCR and immunoblot analysis. The aggregation of short-wavelength opsin (S-opsin) in the murine photoreceptor cells was observed with immunostaining. The effect of S-opsin knockdown on ATF4 expression in the murine photoreceptor cell line was also investigated. Exposure to blue LED light increased the bip , atf4 , and grp94 mRNA levels, induced the expression of ATF4 protein, and increased the levels of ubiquitinated proteins. Exposure to blue LED light in combination with ER stress inducers (tunicamycin and dithiothreitol) induced the aggregation of S-opsin. S-opsin mRNA knockdown prevented the induction of ATF4 expression in response to exposure to blue LED light. These findings indicate that the aggregation of S-opsin induced by exposure to blue LED light causes ER stress, and ATF4 activation in particular.

  3. Blue and Green Light-Induced Phototropism in Arabidopsis thaliana and Lactuca sativa L. Seedlings 1

    Science.gov (United States)

    Steinitz, Benjamin; Ren, Zhangling; Poff, Kenneth L.

    1985-01-01

    Exposure time-response curves for blue and green light-induced phototropic bending in hypocotyls of Arabidopsis thaliana (L.) Heynh. and Lactuca sativa L. seedlings are presented. These seedlings show significant phototropic sensitivity up to 540 to 550 nanometers. Since wave-lengths longer than 560 nanometers do not induce phototropic bending, it is suggested that the response to 510 to 550 nanometers light is mediated by the specific blue light photoreceptor of phototropism. We advise care in the use of green `safelights' for studies of phototropism. PMID:16664021

  4. Synthesis and characterization of a new efficient blue-light- emitting copolymer

    NARCIS (Netherlands)

    Hilberer, A; Brouwer, H.J; van der Scheer, B.J.; Wildeman, J.; Hadziioannou, G

    1995-01-01

    In this paper we present the synthesis, the characterization, and the use in light-emitting diodes of a new blue-light-emitting copolymer, poly[2,5,2'',5''-tetraoctyl-p-terphenyl-4,4''-ylenevinylene-p-phenylenevinylene]. This copolymer, obtained by a poly-Heck reaction, has a fully unsaturated

  5. Growth and maturation of Penaeus indicus under blue and green light

    African Journals Online (AJOL)

    blue and green light. w.o. Emmerson, D.P. Hayes and M. Ngonyame. Prawn Research Unit, Fisheries Development Corporation of South Africa Limited ..... being handled. As light quality has been shown to affect fecundity and growth in other crustaceans (Buikema 1973;. Van Wormhoudt & Ceccaldi 1976), it is not ...

  6. Black carbon or brown carbon? The nature of light-absorbing carbonaceous aerosols

    Directory of Open Access Journals (Sweden)

    M. O. Andreae

    2006-01-01

    Full Text Available Although the definition and measurement techniques for atmospheric 'black carbon' ('BC' or 'elemental carbon'' ('EC' have long been subjects of scientific controversy, the recent discovery of light-absorbing carbon that is not black ('brown carbon, Cbrown' makes it imperative to reassess and redefine the components that make up light-absorbing carbonaceous matter (LAC in the atmosphere. Evidence for the atmospheric presence of Cbrown comes from (1 spectral aerosol light absorption measurements near specific combustion sources, (2 observations of spectral properties of water extracts of continental aerosol, (3 laboratory studies indicating the formation of light-absorbing organic matter in the atmosphere, and (4 indirectly from the chemical analogy of aerosol species to colored natural humic substances. We show that brown carbon may severely bias measurements of 'BC' and 'EC' over vast parts of the troposphere, especially those strongly polluted by biomass burning, where the mass concentration of Cbrown is high relative to that of soot carbon. Chemical measurements to determine 'EC' are biased by the refractory nature of Cbrown as well as by complex matrix interferences. Optical measurements of 'BC' suffer from a number of problems: (1 many of the presently used instruments introduce a substantial bias into the determination of aerosol light absorption, (2 there is no unique conversion factor between light absorption and 'EC' or 'BC' concentration in ambient aerosols, and (3 the difference in spectral properties between the different types of LAC, as well as the chemical complexity of Cbrown, lead to several conceptual as well as practical complications. We also suggest that due to the sharply increasing absorption of Cbrown towards the UV, single-wavelength light absorption measurements may not be adequate for the assessment of absorption of solar radiation in the troposphere. We discuss the possible consequences of these effects for our

  7. Infrared light-absorbing gold/gold sulfide nanoparticles induce cell death in esophageal adenocarcinoma

    Science.gov (United States)

    Li, Yan; Gobin, Andre M; Dryden, Gerald W; Kang, Xinqin; Xiao, Deyi; Li, Su Ping; Zhang, Guandong; Martin, Robert CG

    2013-01-01

    Gold nanoparticles and near infrared-absorbing light are each innocuous to tissue but when combined can destroy malignant tissue while leaving healthy tissue unharmed. This study investigated the feasibility of photothermal ablation therapy for esophageal adenocarcinoma using chitosan-coated gold/gold sulfide (CS-GGS) nanoparticles. A rat esophagoduodenal anastomosis model was used for the in vivo ablation study, and three human esophageal cell lines were used to study the response of cancer cells and benign cells to near infrared light after treatment with CS-GGS. The results indicate that both cancerous tissue and cancer cells took up more gold nanoparticles and were completely ablated after exposure to near infrared light. The benign tissue and noncancerous cells showed less uptake of these nanoparticles, and remained viable after exposure to near infrared light. CS-GGS nanoparticles could provide an optimal endoluminal therapeutic option for near infrared light ablation of esophageal cancer. PMID:23818775

  8. Photochemical eradication of methicillin-resistant Staphylococcus aureus by blue light activation of riboflavin.

    Science.gov (United States)

    Makdoumi, Karim; Goodrich, Ray; Bäckman, Anders

    2017-08-01

    To compare elimination of methicillin-resistant Staphylococcus aureus (MRSA) by exposure of blue light alone and with riboflavin. A reference strain of MRSA was cultured and diluted in PBS with and without riboflavin (0.01%). Fifteen microlitre was added on a microscope slide, creating a fluid layer with a thickness of around 400 microns. Both of the bacterial suspensions were exposed to blue light, and the effect between exposure with and without riboflavin was compared. Evaluation involved two different wavelengths (412 and 450 nm) of blue light with a lower (5.4 J/cm 2 ) and higher dose (approximately 28.5 J/cm 2 ). The effect of 412 nm light was also evaluated for a thicker fluid layer (1.17 mm). After exposure, colony-forming units (CFUs) were determined for each solution. All measurements were repeated eight times. The reductions in bacteria were similar for both wavelengths. With riboflavin, a statistically significant elimination was observed for both 412 and 450 nm (p riboflavin than without it. Using the higher dose, CFU reduction was 99% and 98%, respectively, for 412 and 450 nm light. The bactericidal efficacy was high also in the deeper fluid layer (93%, higher dose). Riboflavin enhanced the antibacterial effect on the exposed MRSA strain of blue light for both 412 and 450 nm blue light. This indicates that blue light could be considered for possible implementation in deep corneal infections. © 2017 Acta Ophthalmologica Scandinavica Foundation. Published by John Wiley & Sons Ltd.

  9. Blue light potentiates neurogenesis induced by retinoic acid-loaded responsive nanoparticles.

    Science.gov (United States)

    Santos, Tiago; Ferreira, Raquel; Quartin, Emanuel; Boto, Carlos; Saraiva, Cláudia; Bragança, José; Peça, João; Rodrigues, Cecília; Ferreira, Lino; Bernardino, Liliana

    2017-09-01

    Neurogenic niches constitute a powerful endogenous source of new neurons that can be used for brain repair strategies. Neuronal differentiation of these cells can be regulated by molecules such as retinoic acid (RA) or by mild levels of reactive oxygen species (ROS) that are also known to upregulate RA receptor alpha (RARα) levels. Data showed that neural stem cells from the subventricular zone (SVZ) exposed to blue light (405nm laser) transiently induced NADPH oxidase-dependent ROS, resulting in β-catenin activation and neuronal differentiation, and increased RARα levels. Additionally, the same blue light stimulation was capable of triggering the release of RA from light-responsive nanoparticles (LR-NP). The synergy between blue light and LR-NP led to amplified neurogenesis both in vitro and in vivo, while offering a temporal and spatial control of RA release. In conclusion, this combinatory treatment offers great advantages to potentiate neuronal differentiation, and provides an innovative and efficient application for brain regenerative therapies. Controlling the differentiation of stem cells would support the development of promising brain regenerative therapies. Blue light transiently increased reactive oxygen species, resulting in neuronal differentiation and increased retinoic acid receptor (RARα) levels. Additionally, the same blue light stimulation was capable of triggering the release of RA from light-responsive nanoparticles (LR-NP). The synergy between blue light and LR-NP led to amplified neurogenesis, while offering a temporal and spatial control of RA release. In this sense, our approach relying on the modulation of endogenous stem cells for the generation of new neurons may support the development of novel clinical therapies. Copyright © 2017 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  10. Evaluation of blue light exposure to beta brainwaves on simulated night driving

    Science.gov (United States)

    Purawijaya, Dandri Aly; Fitri, Lulu Lusianti; Suprijanto

    2015-09-01

    Numbers of night driving accident in Indonesia since 2010 are exponentially rising each year with total of loss more than 50 billion rupiah. One of the causes that contribute to night driving accident is drowsiness. Drowsiness is affected by circadian rhythm resulted from the difference of blue light quality and quantity between night and day. Blue light may effect on human physiology through non-visual pathway by suppressing melatonin hormone suppression that influence drowsiness. Meanwhile, the production of hormones and other activities in brain generate bioelectrical activity such as brainwaves and can be recorded using Electroencephalograph (EEG). Therefore, this research objective is to evaluate the effect of blue light exposure to beta brainwave emergence during night driving simulation to a driver. This research was conducted to 4 male subjects who are able to drive and have a legitimate car driving license. The driving simulator was done using SCANIA Truck Driving Simulator on freeform driving mode in dark environment. Subjects drove for total 32 minutes. The data collections were taken in 2 days with 16 minutes for each day. The 16 minutes were divided again into 8 minutes adaptation in dark and 8 minutes for driving either in blue light exposure or in total darkness. While driving the simulation, subjects' brainwaves were recorded using EEG EMOTIV 14 Channels, exposed by LED monochromatic blue light with 160 Lux from source and angle 45o and sat 1 m in front of the screen. Channels used on this research were for visual (O1; O2), cognition (F3; F4; P7; P8), and motor (FC5; FC6). EEG brainwave result was filtered with EEGLab to obtain beta waves at 13 - 30 Hz frequencies. Results showed that beta waves response to blue light varied for each subject. Blue light exposure either increased or decreased beta waves in 2 minutes pattern and maintaining beta waves on cognition and motor area in 3 out of 4 subjects. Meanwhile, blue light exposure did not maintain

  11. Evidence from Studies with Acifluorfen for Participation of a Flavin-Cytochrome Complex in Blue Light Photoreception for Phototropism of Oat Coleoptiles 12

    Science.gov (United States)

    Leong, Ta-Yan; Briggs, Winslow R.

    1982-01-01

    The diphenyl ether acifluorfen enhances the blue light-induced absorbance change in Triton X100-solubilized crude membrane preparations from etiolated oat (Avena sativa L. cv. Lodi) coleoptiles. Enhancement of the spectral change is correlated with a change in rate of dark reoxidation of a b-type cytochrome. Similar, although smaller, enhancement was obtained with oxyfluorfen, nitrofen, and bifenox. Light-minus-dark difference spectra in the presence and absence of acifluorfen, and the dithionite-reduced-minus oxidized difference spectrum indicate that acifluorfen is acting specifically at a blue light-sensitive cytochrome-flavin complex. Sodium azide, a flavin inhibitor, decreases the light-induced absorbance change significantly, but does not affect the dark reoxidation of the cytochrome. Hence, it is acting on the light reaction, suggesting that the photoreceptor itself is a flavin. Acifluorfen sensitizes phototropism in dark-grown oat seedlings such that the first positive response occurs with blue light fluences as little as one-third of those required to elicit the same response in seedlings grown in the absence of the herbicide. Both this increase in sensitivity to light and the enhancement of the light-induced cytochrome reduction vary with the applied acifluorfen concentration in a similar manner. The herbicide is without effect either on elongation or on the geotropic response of dark-grown oat seedlings, indicating that acifluorfen is acting specifically close to, or at the photoreceptor end of, the stimulus-response chain. It seems likely that the flavin-cytochrome complex serves to transduce the light signal into curvature in phototropism in oats, with the flavin moiety itself serving as the photoreceptor. PMID:16662593

  12. High throughput light absorber discovery, Part 2: Establishing structure–band gap energy relationships

    International Nuclear Information System (INIS)

    Suram, Santosh K.; Newhouse, Paul F.; Zhou, Lan; Van Campen, Douglas G.; Mehta, Apurva; Gregoire, John M.

    2016-01-01

    Combinatorial materials science strategies have accelerated materials development in a variety of fields, and we extend these strategies to enable structure-property mapping for light absorber materials, particularly in high order composition spaces. High throughput optical spectroscopy and synchrotron X-ray diffraction are combined to identify the optical properties of Bi-V-Fe oxides, leading to the identification of Bi 4 V 1.5 Fe 0.5 O 10.5 as a light absorber with direct band gap near 2.7 eV. Here, the strategic combination of experimental and data analysis techniques includes automated Tauc analysis to estimate band gap energies from the high throughput spectroscopy data, providing an automated platform for identifying new optical materials.

  13. Blue-light-induced rapid chloroplast de-anchoring in Vallisneria epidermal cells.

    Science.gov (United States)

    Sakai, Yuuki; Inoue, Shin-ichiro; Harada, Akiko; Shimazaki, Ken-Ichiro; Takagi, Shingo

    2015-01-01

    In the outer periclinal cytoplasm of leaf epidermal cells of an aquatic angiosperm Vallisneria, blue light induces "chloroplast de-anchoring", a rapid decline in the resistance of chloroplasts against centrifugal force. Chloroplast de-anchoring is known induced within 1 min of irradiation with high-fluence-rate blue light specifically, preceding the commencement of chloroplasts migration toward the anticlinal cytoplasm. However, its regulatory mechanism has remained elusive, although pharmacological analysis suggested that a calcium release from intracellular calcium stores is necessary for the response. In search of the responsible photoreceptors, immunoblotting analysis using antibodies against phototropins demonstrated that cross-reactive polypeptides of 120-kDa exist in the plasma-membrane fraction prepared from the leaves. In vitro phosphorylation analysis revealed that 120-kDa polypeptides were phosphorylated by exposure to blue light in a fluence-dependent manner. The blue-light-induced phosphorylation activity was sensitive to a Ser/Thr kinase inhibitor, staurosporine, and unusually was retained at a high level for a long time in darkness. Furthermore, phototropin gene homologs (Vallisneria PHOTOTROPIN1 and PHOTOTROPIN2) expressed in leaves were isolated. We propose that calcium-regulated chloroplast de-anchoring, possibly mediated by phototropins, is an initial process of the blue-light-induced avoidance response of chloroplasts in Vallisneria. © 2014 Institute of Botany, Chinese Academy of Sciences.

  14. Triazolobithiophene Light Absorbing Self-Assembled Monolayers: Synthesis and Mass Spectrometry Applications

    Directory of Open Access Journals (Sweden)

    Denis Séraphin

    2011-10-01

    Full Text Available The synthesis of five light absorbing triazolobithiophenic thiols, which were utilized for producing self-assembled monolayers (SAMs on gold surfaces, is presented. The monolayer formation was monitored by cyclic voltammetry, indicating excellent surface coverage. The new triazolobithiophenic compounds exhibited an absorption maximum around 340 nm, which is close to the emission wavelength of a standard nitrogen laser. Consequently these compounds could be used to aid ionization in laser desorption mass spectrometry (MS.

  15. Literature search on Light Water Reactor (LWR) fuel and absorber rod fabrication, 1960--1976

    Energy Technology Data Exchange (ETDEWEB)

    Sample, C R [comp.

    1977-02-01

    A literature search was conducted to provide information supporting the design of a conceptual Light Water Reactor (LWR) Fuel Fabrication plant. Emphasis was placed on fuel processing and pin bundle fabrication, effects of fuel impurities and microstructure on performance and densification, quality assurance, absorber and poison rod fabrication, and fuel pin welding. All data have been taken from publicly available documents, journals, and books. This work was sponsored by the Finishing Processes-Mixed Oxide (MOX) Fuel Fabrication Studies program at HEDL.

  16. Literature search on Light Water Reactor (LWR) fuel and absorber rod fabrication, 1960--1976

    International Nuclear Information System (INIS)

    Sample, C.R.

    1977-02-01

    A literature search was conducted to provide information supporting the design of a conceptual Light Water Reactor (LWR) Fuel Fabrication plant. Emphasis was placed on fuel processing and pin bundle fabrication, effects of fuel impurities and microstructure on performance and densification, quality assurance, absorber and poison rod fabrication, and fuel pin welding. All data have been taken from publicly available documents, journals, and books. This work was sponsored by the Finishing Processes-Mixed Oxide (MOX) Fuel Fabrication Studies program at HEDL

  17. Phosphorous Diffuser Diverged Blue Laser Diode for Indoor Lighting and Communication

    KAUST Repository

    Chi, Yu-Chieh

    2015-12-21

    An advanced light-fidelity (Li-Fi) system based on the blue Gallium nitride (GaN) laser diode (LD) with a compact white-light phosphorous diffuser is demonstrated for fusing the indoor white-lighting and visible light communication (VLC). The phosphorous diffuser adhered blue GaN LD broadens luminescent spectrum and diverges beam spot to provide ample functionality including the completeness of Li-Fi feature and the quality of white-lighting. The phosphorous diffuser diverged white-light spot covers a radiant angle up to 120o with CIE coordinates of (0.34, 0.37). On the other hand, the degradation on throughput frequency response of the blue LD is mainly attributed to the self-feedback caused by the reflection from the phosphor-air interface. It represents the current state-of-the-art performance on carrying 5.2-Gbit/s orthogonal frequency-division multiplexed 16-quadrature-amplitude modulation (16-QAM OFDM) data with a bit error rate (BER) of 3.1 × 10−3 over a 60-cm free-space link. This work aims to explore the plausibility of the phosphorous diffuser diverged blue GaN LD for future hybrid white-lighting and VLC systems.

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

    Directory of Open Access Journals (Sweden)

    J. Liu

    2016-10-01

    Full Text Available 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.

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

    Science.gov (United States)

    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.

  20. Inhibitory effect of blue light emitting diode on migration and invasion of cancer cells.

    Science.gov (United States)

    Oh, Phil-Sun; Kim, Hyun-Soo; Kim, Eun-Mi; Hwang, Hyosook; Ryu, Hyang Hwa; Lim, SeokTae; Sohn, Myung-Hee; Jeong, Hwan-Jeong

    2017-12-01

    The aim of this study was to determine the effects and molecular mechanism of blue light emitting diode (LED) in tumor cells. A migration and invasion assay for the metastatic behavior of mouse colon cancer CT-26 and human fibrosarcoma HT-1080 cells was performed. Cancer cell migration-related proteins were identified by obtaining a 2-dimensional gel electrophoresis (2-DE) in total cellular protein profile of blue LED-irradiated cancer cells, followed by matrix-assisted laser desorption/ionization-time of flight (MALDI-TOF) analysis of proteins. Protein levels were examined by immunoblotting. Irradiation with blue LED inhibited CT-26 and HT-1080 cell migration and invasion. The anti-metastatic effects of blue LED irradiation were associated with inhibition of matrix metalloproteinase (MMP)-2 and MMP-9 expression. P38 MAPK phosphorylation was increased in blue LED-irradiated CT-26 and HT-1080 cells, but was inhibited after pretreatment with SB203580, a specific inhibitor of p38 MAPK. Inhibition of p38 MAPK phosphorylation by SB203580 treatment increased number of migratory cancer cells in CT-26 and HT-1080 cells, indicating that blue LED irradiation inhibited cancer cell migration via phosphorylation of p38 MAPK. Additionally blue LED irradiation of mice injected with CT-26 cells expressing luciferase decreased early stage lung metastasis compared to untreated control mice. These results indicate that blue LED irradiation inhibits cancer cell migration and invasion in vitro and in vivo. © 2017 Wiley Periodicals, Inc.

  1. Conductive stability of graphene on PET and glass substrates under blue light irradiation

    Science.gov (United States)

    Cao, Xueying; Liu, Xianming; Li, Xiangdi; Lei, Xiaohua; Chen, Weimin

    2018-01-01

    Electrical properties of graphene transparent conductive film under visible light irradiation are investigated. The CVD-grown graphene on Polyethylene Terephthalate (PET) and glass substrates for flexible and rigid touch screen display application are chosen for research. The resistances of graphene with and without gold trichloride (AuCl3) doping are measured in vacuum and atmosphere environment under blue light irradiation. Results show that the conductivities of all samples change slowly under light irradiation. The change rate and degree are related to the substrate material, doping, environment and lighting power. Graphene on flexible PET substrate is more stable than that on rigid glass substrate. Doping can improve the electrical conductivity but induce instability under light irradiation. Finally, the main reason resulting in the graphene resistance slowly increasing under blue light irradiation is analyzed.

  2. Synthesis of dumbbell-like Au nanostructure and its light-absorbance study

    International Nuclear Information System (INIS)

    Shen Jianlei; Xu Yan; Li Kun; Song Shiping; Fan Chunhai

    2013-01-01

    Background: By changing the size or the morphology of Au nanostructure, they can absorb different wavelength light due to the localized surface plasmon resonance (LSPR). Because Au nanorods show good ability to transform light into heat (photothermal effect), they have been wildly used to deliver the drugs and release them controllably. However, when applying such nanostructure for in vivo treatments, Au nanorods must have long aspect ratio which often make it hard to prepare heterogeneous nanostructure. Purpose: A new method to synthesize Au nanostructure with uniform size and to achieve long wavelength light absorbance is needed. This work attempts to synthesize such Au nanostructure by using bio-nano techniques. Methods: New nanostructures are prepared by growing Au nanoparticles on the surface of Au nanorods modified with DNA molecules. Results: Dumbbell-Ikea Au nanostructures were prepared firstly. Its maximum absorbance locates at near ultraviolet region, which means that it can be used as a potential tool for the deep-skin photothermal treatment. Moreover, other two kinds of nanostructures, i.e. Au nanorods with Au splinter at two ends and sea urchin-like nanostructures, are also studied. Conclusions: We successfully fabricated novel Au nanostructures which can be used for drug delivery, surface-enhanced Raman spectroscopy and catalysis. (authors)

  3. Nrf2 protects photoreceptor cells from photo-oxidative stress induced by blue light.

    Science.gov (United States)

    Chen, Wan-Ju; Wu, Caiying; Xu, Zhenhua; Kuse, Yoshiki; Hara, Hideaki; Duh, Elia J

    2017-01-01

    Oxidative stress plays a key role in age-related macular degeneration and hereditary retinal degenerations. Light damage in rodents has been used extensively to model oxidative stress-induced photoreceptor degeneration, and photo-oxidative injury from blue light is particularly damaging to photoreceptors. The endogenous factors protecting photoreceptors from oxidative stress, including photo-oxidative stress, are continuing to be elucidated. In this study, we evaluated the effect of blue light exposure on photoreceptors and its relationship to Nrf2 using cultured murine photoreceptor (661W) cells. 661W cells were exposed to blue light at 2500 lux. Exposure to blue light for 6-24 h resulted in a significant increase in intracellular reactive oxygen species (ROS) and death of 661W cells in a time-dependent fashion. Blue light exposure resulted in activation of Nrf2, as indicated by an increase in nuclear translocation of Nrf2. This was associated with a significant induction of expression of Nrf2 as well as an array of Nrf2 target genes, including antioxidant genes, as indicated by quantitative reverse transcription PCR (qRT-PCR). In order to determine the functional role of Nrf2, siRNA-mediated knockdown studies were performed. Nrf2-knockdown in 661W cells resulted in significant exacerbation of blue light-induced reactive oxygen species levels as well as cell death. Taken together, these findings indicate that Nrf2 is an important endogenous protective factor against oxidative stress in photoreceptor cells. This suggests that drugs targeting Nrf2 could be considered as a neuroprotective strategy for photoreceptors in AMD and other retinal conditions. Copyright © 2016 Elsevier Ltd. All rights reserved.

  4. Blue and Red Light-Evoked Pupil Responses in Photophobic Subjects with TBI.

    Science.gov (United States)

    Yuhas, Phillip T; Shorter, Patrick D; McDaniel, Catherine E; Earley, Michael J; Hartwick, Andrew T E

    2017-01-01

    Photophobia is a common symptom in individuals suffering from traumatic brain injury (TBI). Recent evidence has implicated blue light-sensitive intrinsically photosensitive retinal ganglion cells (ipRGCs) in contributing to the neural circuitry mediating photophobia in migraine sufferers. The goal of this work is to test the hypothesis that ipRGC function is altered in TBI patients with photophobia by assessing pupillary responses to blue and red light. Twenty-four case participants (mean age 43.3; 58% female), with mild TBI and self-reported photophobia, and 12 control participants (mean age 42.6; 58% female) were in this study. After 10 minutes of dark adaptation, blue (470 nm, 1 × 10 phots/s/cm) and red (625 nm, 7 × 10 phots/s/cm) flashing (0.1 Hz) light stimuli were delivered for 30 seconds to the dilated left eye while the right pupil was recorded. The amplitude of normalized pupil fluctuation (constriction and dilation) was quantified using Fourier fast transforms. In both case and control participants, the amplitude of pupil fluctuation was significantly less for the blue light stimuli as compared to the red light stimuli, consistent with a contribution of ipRGCs to these pupil responses. There was no significant difference in the mean pupil fluctuation amplitudes between the two participant groups, but case participants displayed greater variability in their pupil responses to the blue stimulus. Case and control participants showed robust ipRGC-mediated components in their pupil responses to blue light. The results did not support the hypothesis that ipRGCs are "hypersensitive" to light in TBI participants with photophobia. However, greater pupil response variability in the case subjects suggests that ipRGC function may be more heterogeneous in this group.

  5. Blue-light-activated phototropin2 trafficking from the cytoplasm to Golgi/post-Golgi vesicles.

    Science.gov (United States)

    Aggarwal, Chhavi; Banaś, Agnieszka Katarzyna; Kasprowicz-Maluśki, Anna; Borghetti, Carolina; Labuz, Justyna; Dobrucki, Jerzy; Gabryś, Halina

    2014-07-01

    Phototropins are plasma membrane-localized UVA/blue light photoreceptors which mediate phototropism, inhibition of primary hypocotyl elongation, leaf positioning, chloroplast movements, and stomatal opening. Blue light irradiation activates the C-terminal serine/threonine kinase domain of phototropin which autophosphorylates the receptor. Arabidopsis thaliana encodes two phototropins, phot1 and phot2. In response to blue light, phot1 moves from the plasma membrane into the cytosol and phot2 translocates to the Golgi complex. In this study the molecular mechanism and route of blue-light-induced phot2 trafficking are demonstrated. It is shown that Atphot2 behaves in a similar manner when expressed transiently under 35S or its native promoter. The phot2 kinase domain but not blue-light-mediated autophosphorylation is required for the receptor translocation. Using co-localization and western blotting, the receptor was shown to move from the cytoplasm to the Golgi complex, and then to the post-Golgi structures. The results were confirmed by brefeldin A (an inhibitor of the secretory pathway) which disrupted phot2 trafficking. An association was observed between phot2 and the light chain2 of clathrin via bimolecular fluorescence complementation. The fluorescence was observed at the plasma membrane. The results were confirmed using co-immunoprecipitation. However, tyrphostin23 (an inhibitor of clathrin-mediated endocytosis) and wortmannin (a suppressor of receptor endocytosis) were not able to block phot2 trafficking, indicating no involvement of receptor endocytosis in the formation of phot2 punctuate structures. Protein turnover studies indicated that the receptor was continuously degraded in both darkness and blue light. The degradation of phot2 proceeded via a transport route different from translocation to the Golgi complex. © The Author 2014. Published by Oxford University Press on behalf of the Society for Experimental Biology.

  6. The Effect of Different Doses of Blue Light on the Biometric Traits and Photosynthesis of Dill Plants

    OpenAIRE

    Barbara FRĄSZCZAK

    2016-01-01

    The supplementation of blue light to red light enhanced plant growth compared with the use of red alone. The aim of the study was to determine the effect of different doses of blue light on the biometric traits and photosynthesis of dill plants. The plants were grown in pots in a growth chamber. They were grown in red light (100 μmol m-2 s-1) and blue light (from 10 to 50 μmol m-2 s-1) in five combinations. Light emitting diode modules were the source of light. The plants were evaluated every...

  7. Cellular detection of 50 Hz magnetic fields and weak blue light: effects on superoxide levels and genotoxicity.

    Science.gov (United States)

    Höytö, Anne; Herrala, Mikko; Luukkonen, Jukka; Juutilainen, Jukka; Naarala, Jonne

    2017-06-01

    We tested the hypothesis that the effects of 50 Hz magnetic fields (MFs) on superoxide levels and genotoxicity depend on the presence of blue light. Human SH-SY5Y neuroblastoma cells were exposed to a 50 Hz, 100 μT MF with or without non-phototoxic level of blue light for 24 h. We also studied whether these treatments alter responses to menadione, an agent that induces mitochondrial superoxide (O 2 • - ) production and DNA damage. Micronuclei, proliferation, viability, cytosolic and mitochondrial O 2 • - levels were assessed. MF (without blue light) increased cytosolic O 2 • - production and blue light suppressed this effect. Mitochondrial O 2 • - production was reduced by both MF and blue light, but these effects were not additive. Micronucleus frequency was not affected by blue light or MF alone, but blue light (significantly when combined with MF) enhanced menadione-induced micronuclei. The original simple hypothesis (blue light is needed for MF effects) was not supported, but interaction of MF and blue light was nevertheless observed. The results are consistent with MF effects on light-independent radical reactions.

  8. Arabidopsis CRY2 and ZTL mediate blue-light regulation of the transcription factor CIB1 by distinct mechanisms

    Science.gov (United States)

    Liu, Hongtao; Wang, Qin; Liu, Yawen; Zhao, Xiaoying; Imaizumi, Takato; Somers, David E.; Tobin, Elaine M.; Lin, Chentao

    2013-01-01

    Plants possess multiple photoreceptors to mediate light regulation of growth and development, but it is not well understood how different photoreceptors coordinate their actions to jointly regulate developmental responses, such as flowering time. In Arabidopsis, the photoexcited cryptochrome 2 interacts with the transcription factor CRYPTOCHROME-INTERACTING basic helix–loop–helix 1 (CIB1) to activate transcription and floral initiation. We show that the CIB1 protein expression is regulated by blue light; CIB1 is highly expressed in plants exposed to blue light, but levels of the CIB1 protein decreases in the absence of blue light. We demonstrate that CIB1 is degraded by the 26S proteasome and that blue light suppresses CIB1 degradation. Surprisingly, although cryptochrome 2 physically interacts with CIB1 in response to blue light, it is not the photoreceptor mediating blue-light suppression of CIB1 degradation. Instead, two of the three light–oxygen–voltage (LOV)-domain photoreceptors, ZEITLUPE and LOV KELCH PROTEIN 2, but not FLAVIN-BINDING KELCH REPEAT 1, are required for the function and blue-light suppression of degradation of CIB1. These results support the hypothesis that the evolutionarily unrelated blue-light receptors, cryptochrome and LOV-domain F-box proteins, mediate blue-light regulation of the same transcription factor by distinct mechanisms. PMID:24101505

  9. Responses of Crepis japonica induced by supplemental blue light and UV-A radiation.

    Science.gov (United States)

    Constantino, L F da S; Nascimento, L B Dos S; Casanova, L M; Moreira, N Dos S; Menezes, E A; Esteves, R L; Costa, S S; Tavares, E S

    2017-02-15

    Crepis japonica (L.) D.C. (Asteraceae), a weed with antioxidant, antiallergenic, antiviral and antitumor properties displays both medicinal properties and nutritional value. This study aims to assess the effects of a supplementation of blue light and UV-A radiation on the growth, leaf anatomical structure and phenolic profile of the aerial parts of Crepis japonica. Plants were grown under two light treatments: W (control - white light), W + B (white light supplemented with blue light) and W + UV-A (white light supplemented with UV-A radiation). We recorded the length, width, and weight of fresh and dry leaves, the thickness of the epidermis and mesophyll, and stomata density. The phenolic profiles of the aqueous extracts of the aerial parts were analyzed by HPLC-DAD. There was an increase in the leaf size, stomatal density, and phenolic production, and a thickening of the mesophyll and epidermis. UV-A radiation increased the phenolic production more than blue light. Blue light and UV-A radiation both improved the production of caffeic acid by about 6 and 3 times, respectively, in comparison to control. This compound was first reported as a constituent of the extract from the aerial parts together with caftaric acid. UV-A also promoted the production of chlorogenic acid (about 1.5 times in comparison to the control). We observed that the morphological and chemical parameters of C. japonica are modified in response to blue light and UV-A radiation, which can be used as tools in the cultivation of this species in order to improve its medicinal properties and nutritional value.

  10. Blue-light dependent reactive oxygen species formation by Arabidopsis cryptochrome may define a novel evolutionarily conserved signaling mechanism.

    Science.gov (United States)

    Consentino, Laurent; Lambert, Stefan; Martino, Carlos; Jourdan, Nathalie; Bouchet, Pierre-Etienne; Witczak, Jacques; Castello, Pablo; El-Esawi, Mohamed; Corbineau, Francoise; d'Harlingue, Alain; Ahmad, Margaret

    2015-06-01

    Cryptochromes are widespread blue-light absorbing flavoproteins with important signaling roles. In plants they mediate de-etiolation, developmental and stress responses resulting from interaction with downstream signaling partners such as transcription factors and components of the proteasome. Recently, it has been shown that Arabidopsis cry1 activation by blue light also results in direct enzymatic conversion of molecular oxygen (O2 ) to reactive oxygen species (ROS) and hydrogen peroxide (H2 O2 ) in vitro. Here we explored whether direct enzymatic synthesis of ROS by Arabidopsis cry1 can play a physiological role in vivo. ROS formation resulting from cry1 expression was measured by fluorescence assay in insect cell cultures and in Arabidopsis protoplasts from cryptochrome mutant seedlings. Cell death was determined by colorimetric assay. We found that ROS formation results from cry1 activation and induces cell death in insect cell cultures. In plant protoplasts, cryptochrome activation results in rapid increase in ROS formation and cell death. We conclude that ROS formation by cryptochromes may indeed be of physiological relevance and could represent a novel paradigm for cryptochrome signaling. © 2015 The Authors. New Phytologist © 2015 New Phytologist Trust.

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

    Energy Technology Data Exchange (ETDEWEB)

    Schmehl, Russell H. [Tulane Univ., New Orleans, LA (United States)

    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.

  12. Output blue light evaluation for phosphor based smart white LED wafer level packages.

    Science.gov (United States)

    Kolahdouz, Zahra; Rostamian, Ali; Kolahdouz, Mohammadreza; Ma, Teng; van Zeijl, Henk; Zhang, Kouchi

    2016-02-22

    This study presents a blue light detector for evaluating the output light of phosphor based white LED package. It is composed of a silicon stripe-shaped photodiode designed and implemented in a 2 μm BiCMOS process which can be used for wafer level integration of different passive and active devices all in just 5 lithography steps. The final device shows a high selectivity to blue light. The maximum responsivity at 480 nm is matched with the target blue LED illumination. The designed structure have better responsivity compared to simple photodiode structure due to reducing the effect of dead layer formation close to the surface because of implantation. It has also a two-fold increase in the responsivity and quantum efficiency compared to previously similar published sensors.

  13. The plasma membrane-associated NADH oxidase of spinach leaves responds to blue light

    Science.gov (United States)

    Morre, D. James; Penel, Claude; Greppin, Hubert; Morre, Dorothy M.

    2002-01-01

    The plasma membrane-associated NADH oxidase (NOX) of spinach leaf disks is characterized by oscillations in activity with a regular period length of ca. 24 min. Within a single population of plants exposed to light at the same time, NOX activities of all plants function synchronously. Exposure of plants transferred from darkness to blue light (495 nm, 2 min, 50 micromoles m-2 s-1) resulted in a complex response pattern but with a new maximum in the rate of NOX activity 36 (24+12) min after illumination and then with maxima in the rate of NOX activity every 24 min thereafter. Transient maxima in NOX activity were observed as well after 9.3 + /- 1.4 and 20.7 +/- 2.1 min. The blue light response differed from the response to red (650 nm, 10 min, 50 micromoles m-2 s-1) or white light where activity maxima were initiated 12 min after the light exposure followed by maxima every 24 min thereafter. Green or yellow light was ineffective. The light response was independent of the time in the 24-min NOX cycle when the light was given. The net effects of blue and red light were ultimately the same with a new maximum in the rate of NOX activity at 12+24=36 min (and every 24 min thereafter), but the mechanisms appear to be distinct.

  14. Photo Inactivation of Streptococcus mutans Biofilm by Violet-Blue light.

    Science.gov (United States)

    Gomez, Grace F; Huang, Ruijie; MacPherson, Meoghan; Ferreira Zandona, Andrea G; Gregory, Richard L

    2016-09-01

    Among various preventive approaches, non-invasive phototherapy/photodynamic therapy is one of the methods used to control oral biofilm. Studies indicate that light at specific wavelengths has a potent antibacterial effect. The objective of this study was to determine the effectiveness of violet-blue light at 380-440 nm to inhibit biofilm formation of Streptococcus mutans or kill S. mutans. S. mutans UA159 biofilm cells were grown for 12-16 h in 96-well flat-bottom microtiter plates using tryptic soy broth (TSB) or TSB with 1 % sucrose (TSBS). Biofilm was irradiated with violet-blue light for 5 min. After exposure, plates were re-incubated at 37 °C for either 2 or 6 h to allow the bacteria to recover. A crystal violet biofilm assay was used to determine relative densities of the biofilm cells grown in TSB, but not in TSBS, exposed to violet-blue light. The results indicated a statistically significant (P mutans growth and reduce the formation of S. mutans biofilm. This in vitro study demonstrated that violet-blue light has the capacity to inhibit S. mutans biofilm formation. Potential clinical applications of light therapy in the future remain bright in preventing the development and progression of dental caries.

  15. The Effects of Red and Blue Lights on Circadian Variations in Cortisol, Alpha Amylase, and Melatonin

    Directory of Open Access Journals (Sweden)

    Mariana G. Figueiro

    2010-01-01

    Full Text Available The primary purpose of the present study was to expand our understanding of the impact of light exposures on the endocrine and autonomic systems as measured by acute cortisol, alpha amylase, and melatonin responses. We utilized exposures from narrowband long-wavelength (red and from narrow-band short-wavelength (blue lights to more precisely understand the role of the suprachiasmatic nuclei (SCN in these responses. In a within-subjects experimental design, twelve subjects periodically received one-hour corneal exposures of 40 lux from the blue or from the red lights while continuously awake for 27 hours. Results showed-that, as expected, only the blue light reduced nocturnal melatonin. In contrast, both blue and red lights affected cortisol levels and, although less clear, alpha amylase levels as well. The present data bring into question whether the nonvisual pathway mediating nocturnal melatonin suppression is the same as that mediating other responses to light exhibited by the endocrine and the autonomic nervous systems.

  16. Blue Light Action on Mitochondria Leads to Cell Death by Necroptosis.

    Science.gov (United States)

    Del Olmo-Aguado, Susana; Núñez-Álvarez, Claudia; Osborne, Neville N

    2016-09-01

    Blue light impinging on the many mitochondria associated with retinal ganglion cells (RGCs) in situ has the potential of eliciting necroptosis through an action on RIP1/RIP3 to stimulate RGC death in diseases like glaucoma and diabetic retinopathy. Cells in culture die when exposed to blue light. The death process is mitochondria-dependent and is known to involve a decrease in the production of ATP, a generation of ROS, the activation of poly-(ADP-ribose) polymerase, the stimulation of apoptosis-inducing factor (AIF) as well as the up-regulation of heme-oxygenase-1 (HO-1). Our present results show that blue light-induced activation of AIF is not directly linked with the stimulation of RIP1/RIP3. Down-regulation of RIP1/RIP3 did not influence AIF. AIF activation therefore appears to enhance the rate of necroptosis by a direct action on DNA breakdown, the end stage of necroptosis. This implies that silencing of AIF mRNA may provide a degree of protection to blue light insult. Also, necrostatin-1 attenuated an increased turnover of HO-1 mRNA caused by blue light to suggest an indirect inhibition of necroptosis, caused by the action of necrostatin-1 on RIP1/RIP3 to reduce oxidative stress. This is supported by the finding that gene silencing of RIP1 and RIP3 has no effect on HO-1. We therefore conclude that inhibitors of RIP kinase might be more specific than necrostatin-1 as a neuroprotective agent to blunt solely necroptosis caused by blue light.

  17. Daytime Blue Light Enhances the Nighttime Circadian Melatonin Inhibition of Human Prostate Cancer Growth.

    Science.gov (United States)

    Dauchy, Robert T; Hoffman, Aaron E; Wren-Dail, Melissa A; Hanifin, John P; Warfield, Benjamin; Brainard, George C; Xiang, Shulin; Yuan, Lin; Hill, Steven M; Belancio, Victoria P; Dauchy, Erin M; Smith, Kara; Blask, David E

    2015-12-01

    Light controls pineal melatonin production and temporally coordinates circadian rhythms of metabolism and physiology in normal and neoplastic tissues. We previously showed that peak circulating nocturnal melatonin levels were 7-fold higher after daytime spectral transmittance of white light through blue-tinted (compared with clear) rodent cages. Here, we tested the hypothesis that daytime blue-light amplification of nocturnal melatonin enhances the inhibition of metabolism, signaling activity, and growth of prostate cancer xenografts. Compared with male nude rats housed in clear cages under a 12:12-h light:dark cycle, rats in blue-tinted cages (with increased transmittance of 462-484 nm and decreased red light greater than 640 nm) evinced over 6-fold higher peak plasma melatonin levels at middark phase (time, 2400), whereas midlight-phase levels (1200) were low (less than 3 pg/mL) in both groups. Circadian rhythms of arterial plasma levels of linoleic acid, glucose, lactic acid, pO2, pCO2, insulin, leptin, and corticosterone were disrupted in rats in blue cages as compared with the corresponding entrained rhythms in clear-caged rats. After implantation with tissue-isolated PC3 human prostate cancer xenografts, tumor latency-to-onset of growth and growth rates were markedly delayed, and tumor cAMP levels, uptake-metabolism of linoleic acid, aerobic glycolysis (Warburg effect), and growth signaling activities were reduced in rats in blue compared with clear cages. These data show that the amplification of nighttime melatonin levels by exposing nude rats to blue light during the daytime significantly reduces human prostate cancer metabolic, signaling, and proliferative activities.

  18. Structural and evolutionary aspects of algal blue light receptors of the cryptochrome and aureochrome type.

    Science.gov (United States)

    Essen, Lars-Oliver; Franz, Sophie; Banerjee, Ankan

    2017-10-01

    Blue-light reception plays a pivotal role for algae to adapt to changing environmental conditions. In this review we summarize the current structural and mechanistic knowledge about flavin-dependent algal photoreceptors. We especially focus on the cryptochrome and aureochrome type photoreceptors in the context of their evolutionary divergence. Despite similar photochemical characteristics to orthologous photoreceptors from higher plants and animals the algal blue-light photoreceptors have developed a set of unique structural and mechanistic features that are summarized below. Copyright © 2017 Elsevier GmbH. All rights reserved.

  19. Importance of 'blue' photon levels for lettuce seedlings grown under red-light-emitting diodes

    Science.gov (United States)

    Hoenecke, M. E.; Bula, R. J.; Tibbitts, T. W.

    1992-01-01

    Light-emitting diodes (LEDs) with high-intensity output are being studied as a photosynthetic light source for plants. High-output LEDs have peak emission at approximately 660 nm concentrated in a waveband of +/- 30 nm. Lettuce (Lactuca sativa Grand Rapids') seedlings developed extended hypocotyls and elongated cotyledons when grown under these LEDs as a sole source of irradiance. This extension and elongation was prevented when the red LED radiation was supplemented with more than 15 micromoles m-2 s-1 of 400- to 500-nm photons from blue fluorescent lamps. Blue radiation effects were independent of the photon level of the red radiation.

  20. Subadditive responses to extremely short blue and green pulsed light on visual evoked potentials, pupillary constriction and electroretinograms.

    Science.gov (United States)

    Lee, Soomin; Uchiyama, Yuria; Shimomura, Yoshihiro; Katsuura, Tetsuo

    2017-11-17

    The simultaneous exposure to blue and green light was reported to result in less melatonin suppression than monochromatic exposure to blue or green light. Here, we conducted an experiment using extremely short blue- and green-pulsed light to examine their visual and nonvisual effects on visual evoked potentials (VEPs), pupillary constriction, electroretinograms (ERGs), and subjective evaluations. Twelve adult male subjects were exposed to three light conditions: blue-pulsed light (2.5-ms pulse width), green-pulsed light (2.5-ms pulse width), and simultaneous blue- and green-pulsed light with white background light. We measured the subject's pupil diameter three times in each condition. Then, after 10 min of rest, the subject was exposed to the same three light conditions. We measured the averaged ERG and VEP during 210 pulsed-light exposures in each condition. We also determined subjective evaluations using a visual analog scale (VAS) method. The pupillary constriction during the simultaneous exposure to blue- and green-pulsed light was significantly lower than that during the blue-pulsed light exposure despite the double irradiance intensity of the combination. We also found that the b/|a| wave of the ERGs during the simultaneous exposure to blue- and green-pulsed light was lower than that during the blue-pulsed light exposure. We confirmed the subadditive response to pulsed light on pupillary constriction and ERG. However, the P100 of the VEPs during the blue-pulsed light were smaller than those during the simultaneous blue- and green-pulsed light and green-pulsed light, indicating that the P100 amplitude might depend on the luminance of light. Our findings demonstrated the effect of the subadditive response to extremely short pulsed light on pupillary constriction and ERG responses. The effects on ipRGCs by the blue-pulsed light exposure are apparently reduced by the simultaneous irradiation of green light. The blue versus yellow (b/y) bipolar cells in the

  1. Blue light-mediated transcriptional activation and repression of gene expression in bacteria

    Science.gov (United States)

    Jayaraman, Premkumar; Devarajan, Kavya; Chua, Tze Kwang; Zhang, Hanzhong; Gunawan, Erry; Poh, Chueh Loo

    2016-01-01

    Light-regulated modules offer unprecedented new ways to control cellular behavior in precise spatial and temporal resolution. The availability of such tools may dramatically accelerate the progression of synthetic biology applications. Nonetheless, current optogenetic toolbox of prokaryotes has potential issues such as lack of rapid and switchable control, less portable, low dynamic expression and limited parts. To address these shortcomings, we have engineered a novel bidirectional promoter system for Escherichia coli that can be induced or repressed rapidly and reversibly using the blue light dependent DNA-binding protein EL222. We demonstrated that by modulating the dosage of light pulses or intensity we could control the level of gene expression precisely. We show that both light-inducible and repressible system can function in parallel with high spatial precision in a single cell and can be switched stably between ON- and OFF-states by repetitive pulses of blue light. In addition, the light-inducible and repressible expression kinetics were quantitatively analysed using a mathematical model. We further apply the system, for the first time, to optogenetically synchronize two receiver cells performing different logic behaviors over time using blue light as a molecular clock signal. Overall, our modular approach layers a transformative platform for next-generation light-controllable synthetic biology systems in prokaryotes. PMID:27353329

  2. Effect of LED Blue Light on Penicillium digitatum and Penicillium italicum Strains.

    Science.gov (United States)

    Lafuente, María T; Alférez, Fernando

    2015-11-01

    Studies on the antimicrobial properties of light have considerably increased due in part to the development of resistance to actual control methods. This study investigates the potential of light-emitting diodes (LED) blue light for controlling Penicillium digitatum and Penicillium italicum. These fungi are the most devastating postharvest pathogens of citrus fruit and cause important losses due to contaminations and the development of resistant strains against fungicides. The effect of different periods and quantum fluxes, delaying light application on the growth and morphology of P. digitatum strains resistant and sensitive to fungicides, and P. italicum cultured at 20°C was examined. Results showed that blue light controls the growth of all strains and that its efficacy increases with the quantum flux. Spore germination was always avoided by exposing the cultures to high quantum flux (700 μmol m(-2) s(-1) ) for 18 h. Continuous light had an important impact on the fungus morphology and a fungicidal effect when applied at a lower quantum flux (120 μmol m(-2) s(-1) ) to a growing fungus. Sensitivity to light increased with mycelium age. Results show that blue light may be a tool for P. digitatum and P. italicum infection prevention during handling of citrus fruits. © 2015 The American Society of Photobiology.

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

    Science.gov (United States)

    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.

  4. Blue light versus red light for photodynamic therapy of basal cell carcinoma in patients with Gorlin syndrome: A bilaterally controlled comparison study.

    Science.gov (United States)

    Maytin, Edward V; Kaw, Urvashi; Ilyas, Muneeb; Mack, Judith A; Hu, Bo

    2018-02-19

    Photodynamic therapy (PDT) is a non-scarring alternative for treating basal cell carcinoma (BCC) in patients with Basal Cell Nevus Syndrome (BCNS), also known as Gorlin syndrome. In Europe, red light (635 nm) is the predominant source for PDT, whereas in the United States blue light (400 nm) is more widely available. The objective of this study was to conduct a head-to-head comparison of blue light and red light PDT in the same BCNS patients. In a pilot study of three patients with 141 BCC lesions, 5-aminolevulinate (20% solution) was applied to all tumors. After 4 hours, half of the tumors were illuminated with blue light and the remainder with red light. To ensure safety while treating this many tumors simultaneously, light doses were escalated gradually. Six treatments were administered in three biweekly sessions over 4 months, with a final evaluation at 6 months. Tumor status was documented with high-resolution photographs. Persistent lesions were biopsied at 6 months. Clearance rates after blue light (98%) were slightly better than after red light (93%), with blue light shown to be statistically non-inferior to red light. Eight suspicious lesions were biopsied, 5 after red light (5/5 were BCC) and 3 after blue light (1 was BCC). Blue light PDT was reportedly less painful. Blue light and red light PDT appear to be equally safe and perhaps equally effective for treating BCC tumors in BCNS patients. Further studies to evaluate long-term clearance after blue light PDT are needed. Copyright © 2018 Elsevier B.V. All rights reserved.

  5. The effects of low-intensity narrow-band blue-light treatment compared to bright white-light treatment in seasonal affective disorder.

    Science.gov (United States)

    Meesters, Ybe; Duijzer, Wianne B; Hommes, Vanja

    2018-05-01

    Ever since a new photoreceptor was discovered with a highest sensitivity to 470-490 nm blue light, it has been speculated that blue light has some advantages in the treatment of Seasonal Affective Disorder (SAD) over more traditional treatments. In this study we compared the effects of exposure to narrow-band blue light (BLUE) to those of broad-wavelength white light (BLT) in the treatment of SAD. In a 15-day design, 45 patients suffering from SAD completed 30-min sessions of light treatment on 5 consecutive days. 21 subjects received white-light treatment (BLT, broad-wavelength without UV, 10 000 lx, irradiance 31.7 W/m 2 ), 24 subjects received narrow-band blue light (BLUE, 100 lx, irradiance 1.0 W/m 2 ). All participants completed weekly questionnaires concerning mood and energy levels, and were also assessed by means of the SIGH-SAD, which is the primary outcome measure. On day 15, SIGH-SAD ratings were significantly lower than on day 1 (BLT 73.2%, effect size 3.37; BLUE 67%, effect size 2.63), which outcomes were not statistically significant different between both conditions. Small sample size. Light treatment is an effective treatment for SAD. The use of narrow-band blue light is equally effective as a treatment using bright white-light. Copyright © 2018 Elsevier B.V. All rights reserved.

  6. Combined Effects of Blue and Ultraviolet Lights on the Accumulation of Flavonoids in Tartary Buckwheat Sprouts

    Directory of Open Access Journals (Sweden)

    Ji Hongbin

    2016-06-01

    Full Text Available The effects of blue and UV-A (365 nm/UV-C (254 nm or their combinations on the levels of total flavonoids, rutin, quercetin, phenylalanine ammonialyase (PAL, chalcone isomerase (CHI, rutin degrading enzymes (RDEs and 1,1-diphenyl-2-picrylhydrazyl (DPPH radical scavenging activity in tartary buckwheat sprouts were investigated in this study. The total flavonoids content in the tartary buckwheat sprouts irradiated with blue light followed by UV-C (BL+UV-C raised by 10%, compared with the opposite combination sequence (UV-C+BL. However, blue light did not show the same results when combined with UV-A, and their combinations on the accumulation of total flavonoids were still lower than that of UV-A/UV-C. Key enzymes (PAL, CHI and RDEs revealed a significant correlation with total flavonoids in tartary buckwheat sprouts.

  7. In-car nocturnal blue light exposure improves motorway driving: a randomized controlled trial.

    Science.gov (United States)

    Taillard, Jacques; Capelli, Aurore; Sagaspe, Patricia; Anund, Anna; Akerstedt, Torbjorn; Philip, Pierre

    2012-01-01

    Prolonged wakefulness greatly decreases nocturnal driving performance. The development of in-car countermeasures is a future challenge to prevent sleep-related accidents. The aim of this study is to determine whether continuous exposure to monochromatic light in the short wavelengths (blue light), placed on the dashboard, improves night-time driving performance. In this randomized, double-blind, placebo-controlled, cross-over study, 48 healthy male participants (aged 20-50 years) drove 400 km (250 miles) on motorway during night-time. They randomly and consecutively received either continuous blue light exposure (GOLite, Philips, 468 nm) during driving or 2*200 mg of caffeine or placebo of caffeine before and during the break. Treatments were separated by at least 1 week. The outcomes were number of inappropriate line crossings (ILC) and mean standard deviation of the lateral position (SDLP). Eight participants (17%) complained about dazzle during blue light exposure and were removed from the analysis. Results from the 40 remaining participants (mean age ± SD: 32.9±11.1) showed that countermeasures reduced the number of inappropriate line crossings (ILC) (F(2,91.11) = 6.64; pquality, quantity and timing of 3 subsequent nocturnal sleep episodes. Despite a lesser tolerance, a non-inferior efficacy of continuous nocturnal blue light exposure compared with caffeine suggests that this in-car countermeasure, used occasionally, could be used to fight nocturnal sleepiness at the wheel in blue light-tolerant drivers, whatever their age. More studies are needed to determine the reproducibility of data and to verify if it can be generalized to women. ClinicalTrials.gov NCT01070004.

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

    Science.gov (United States)

    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.

  9. Source attribution of insoluble light-absorbing particles in seasonal snow across northern China

    Directory of Open Access Journals (Sweden)

    R. Zhang

    2013-06-01

    Full Text Available Seasonal snow samples obtained at 46 sites in 6 provinces of China in January and February 2010 were analyzed for a suite of chemical species and these data are combined with previously determined concentrations of insoluble light-absorbing particles (ILAP, including all particles that absorb light in the 650–700 nm wavelength interval. The ILAP, together with 14 other analytes, are used as input to a positive matrix factorization (PMF receptor model to explore the sources of ILAP in the snow. The PMF analysis for ILAP sources is augmented with backward trajectory cluster analysis and the geographic locations of major source areas for the three source types. The two analyses are consistent and indicate that three factors/sources were responsible for the measured light absorption of snow: a soil dust source, an industrial pollution source, and a biomass and / or biofuel burning source. Soil dust was the main source of the ILAP, accounting for ~53% of ILAP on average.

  10. Blue- and red-light regulation of the cell cycle in Chlamydomonas reinhardtii (Chlorophyta)

    Czech Academy of Sciences Publication Activity Database

    Oldenhof, H.; Zachleder, Vilém; van den Ende, H.

    2006-01-01

    Roč. 41, č. 3 (2006), s. 313-320 ISSN 0967-0262 R&D Projects: GA AV ČR(CZ) KJB5020305 Institutional research plan: CEZ:AV0Z50200510 Keywords : blue light * cell cycle * cell division Subject RIV: EE - Microbiology, Virology Impact factor: 1.293, year: 2006

  11. Visible light induced photobleaching of methylene blue over melamine-doped TiO2 nanocatalyst

    Science.gov (United States)

    TiO2 doping with N-rich melamine produced a stable, active and visible light sentisized nanocatalyst that showed a remarkable efficiency towards the photobleaching of a model compound – methylene blue (MB) in aqueous solution. The photobleaching followed a mixed reaction order ki...

  12. Charge transport and recombination in polyspirobifluorene blue light-emitting diodes

    NARCIS (Netherlands)

    Nicolai, H.T.; Hof, A.; Oosthoek, J.L.M.; Blom, P.W.M.

    2011-01-01

    The charge transport in blue light-emitting polyspirobifluorene is investigated by both steady-state current-voltage measurements and transient electroluminescence. Both measurement techniques yield consistent results and show that the hole transport is space-charge limited. The electron current is

  13. Effect of blue LED light intensity on carotenoid accumulation in citrus juice sacs.

    Science.gov (United States)

    Zhang, Lancui; Ma, Gang; Yamawaki, Kazuki; Ikoma, Yoshinori; Matsumoto, Hikaru; Yoshioka, Terutaka; Ohta, Satoshi; Kato, Masaya

    2015-09-01

    In the present study, the effects of blue LED light intensity on carotenoid accumulation and expression of genes related to carotenoid biosynthesis were investigated in the juice sacs of Satsuma mandarin (Citrus unshiu Marc.) and Valencia orange (Citrus sinensis Osbeck) in vitro. The results showed that 100 μmol m(-2)s(-1) blue LED light (100B) was effective for increasing carotenoid content, especially β-cryptoxanthin, in Satsuma mandarin after cultured in vitro for four weeks. In Valencia orange, in contrast, 50 μmol m(-2)s(-1) blue LED light (50B) treatment was effective for inducing carotenoid accumulation through increasing the contents of two major carotenoids, all-trans-violaxanthin and 9-cis-violaxanthin. In addition, gene expression results showed that the simultaneous increases in the expression of genes (CitPSY, CitPDS, CitZDS, CitLCYb2, and CitHYb) involved in producing β,β-xanthophylls were well consistent with the accumulation of β-cryptoxanthin in Satsuma mandarin under 100B, and violaxanthin in Valencia orange under 50B. The results presented herein contribute to further elucidating the regulatory mechanism of carotenoid accumulation by blue LED light. Copyright © 2015 Elsevier GmbH. All rights reserved.

  14. Blue and red light combination LED phototherapy for acne vulgaris in patients with skin phototype IV.

    Science.gov (United States)

    Lee, Seung Yoon; You, Chung Eui; Park, Mi Youn

    2007-02-01

    Blue light is effective for acne treatment, inducing photodynamic destruction of Propionibacterium acnes (P. acnes). This study was designed to investigate the efficacy of combined blue and red light-emitting diode (LED) phototherapy for acne vulgaris. Twenty-four patients with mild to moderately severe facial acne were treated with quasimonochromatic LED devices, alternating blue (415 nm) and red (633 nm) light. The treatment was performed twice a week for 4 weeks. Objective assays of the skin condition were carried out before and after treatment at each treatment session. Clinical assessments were conducted before treatment, after the 2nd, 4th, and 6th treatment sessions and at 2, 4, and 8 weeks after the final treatment by grading and lesion counting. The final mean percentage improvements in non-inflammatory and inflammatory lesions were 34.28% and 77.93%, respectively. Instrumental measurements indicated that the melanin levels significantly decreased after treatment. Brightened skin tone and improved skin texture were spontaneously reported by 14 patients. Blue and red light combination LED phototherapy is an effective, safe and non-painful treatment for mild to moderately severe acne vulgaris, particularly for papulopustular acne lesions. (c) 2007 Wiley-Liss, Inc.

  15. Reconsidering the effects of blue-light installation for prevention of railway suicides.

    Science.gov (United States)

    Ichikawa, Masao; Inada, Haruhiko; Kumeji, Minae

    2014-01-01

    A recent preliminary communication suggested that the calming effect of blue lights installed at the ends of railway platforms in Japan reduced suicides by 84%. This estimate is potentially misleading from an epidemiological point of view and is reconsidered in the present study. Governmental data listing all railway suicide attempts in Japan from April 2002 to March 2012 were used to investigate the proportion of suicide attempts within station premises, where blue lights are potentially installed, and at night, when they would be lit. For those suicide attempts within station premises, we also estimated the proportion that occurred at the ends of the platforms at night. Of 5841 total reported suicide attempts, 43% occurred within the station premises, 43% occurred at night (from 18:00 to 05:59), and 14% occurred both within the station premises and at night. Of the 2535 attempts within station premises, 32% occurred at night and 28% at most were at the end of a platform at night. The exact proportion of nighttime suicide attempts at the ends of railway platforms was not calculable. Nonetheless, the proportion of suicide attempts that is potentially preventable by blue lights should be less than our conservative estimate. The installation of blue lights on platforms, even were they to have some effect in preventing railway suicides at night, would have a much smaller impact than previously estimated. © 2013 Published by Elsevier B.V.

  16. Furopyridine derivatives as host materials for solution processed blue phosphorescent organic light-emitting diodes

    Energy Technology Data Exchange (ETDEWEB)

    Yook, Kyoung Soo; Lee, Jun Yeob, E-mail: leej17@dankook.ac.kr

    2014-07-01

    Soluble blue phosphorescent organic light-emitting diodes were developed using a pyridofuropyridine derivative, 3-(3-(carbazole-9-yl)phenyl) pyrido[3′,2′:4,5]furo[2,3-b]pyridine (CzPFP), and a benzofuropyridine derivative, 6-(3-(carbazole-9-yl)phenyl)benzofuro[2,3-b]pyridine (PCz-6BFP) as host materials. The CzPFP and PCz-6BFP hosts formed a smooth film morphology with a surface roughness less than 0.5 nm after spin coating. The PCz-6BFP host showed better quantum efficiency than the CzPFP host and a high quantum efficiency of 19.5% was achieved in solution processed blue phosphorescent organic light-emitting diodes using the PCz-6BFP host. - Highlights: • High quantum efficiency of 19.5% in blue phosphorescent organic light-emitting diodes • Stable film morphology using benzofuropyridine and pyridofuropyridine derivatives • High efficiency solution processed blue phosphorescent organic light-emitting diodes.

  17. Exciton quenching at PEDOT:PSS anode in polymer blue-light-emitting diodes

    NARCIS (Netherlands)

    Abbaszadeh, D.; Wetzelaer, G.A.H.; Nicolai, H.T.; Blom, P.W.M.

    2014-01-01

    The quenching of excitons at the poly(3,4-ethylenedioxythiophene):poly(styrenesulfonic acid) PEDOT:PSS) anode in blue polyalkoxyspirobifluorene-arylamine polymer light-emitting diodes is investigated. Due to the combination of a higher electron mobility and the presence of electron traps, the

  18. Exciton quenching at PEDOT : PSS anode in polymer blue-light-emitting diodes

    NARCIS (Netherlands)

    Abbaszadeh, D.; Wetzelaer, G. A. H.; Nicolai, H. T.; Blom, P. W. M.

    2014-01-01

    The quenching of excitons at the poly(3,4-ethylenedioxythiophene): poly(styrenesulfonic acid) (PEDOT:PSS) anode in blue polyalkoxyspirobifluorene-arylamine polymer light-emitting diodes is investigated. Due to the combination of a higher electron mobility and the presence of electron traps, the

  19. Indirect blue light does not suppress nocturnal salivary melatonin in humans in an automobile setting.

    Science.gov (United States)

    Lerchl, Alexander; Schindler, Carina; Eichhorn, Karsten; Kley, Franziska; Erren, Thomas C

    2009-09-01

    In 2007, the International Agency for Research on Cancer (IARC) classified shift work that involves circadian disruption as being probably carcinogenic to humans (Group 2A). In this context, light exposure during the night plays a key role because it can suppress nocturnal melatonin levels when exposures exceed a certain threshold. Blue light around 464 nm is most effective in suppressing melatonin because of the spectral sensitivity of melanopsin, a recently discovered photopigment in retinal ganglion cells; the axons of these cells project to the suprachiasmatic nucleus, a circadian master clock in the brain. Due to advances in light technologies, normal tungsten light bulbs are being replaced by light-emitting diodes which produce quasi-monochromatic or white light. The objective of this study was to assess whether the light-melanopsin-melatonin axis might be affected in automobiles at night which employ the new generation diodes. To this end, we have tested in an experimental automobile setting whether indirect blue light (lambda(max) = 465 nm) at an intensity of 0.22 or 1.25 lx can suppress salivary melatonin levels in 12 male volunteers (age range 17-27 years) who served as their own controls. Daytime levels were low (2.7 +/- 0.5 pg/mL), and night-time levels without light exposure were high (14.5 +/- 1.1 pg/mL), as expected. Low-intensity light exposures had no significant effect on melatonin levels (0.22 lx: 17.2 +/- 2.8 pg/mL; P > 0.05; 1.25 lx: 12.6 +/- 2.0 pg/mL; P > 0.05). It is concluded that indirect blue light exposures in automobiles up to 1.25 lx do not cause unintentional chronodisruption via melatonin suppression.

  20. The ultrastructure of rabbit sclera after scleral crosslinking with riboflavin and blue light of different intensities.

    Science.gov (United States)

    Karl, Anett; Makarov, Felix N; Koch, Christian; Körber, Nicole; Schuldt, Carsten; Krüger, Martin; Reichenbach, Andreas; Wiedemann, Peter; Bringmann, Andreas; Iseli, Hans Peter; Francke, Mike

    2016-08-01

    We aimed to determine the ultrastructural changes of collagen fibrils and cells in the rabbit sclera after scleral crosslinking using riboflavin and blue light of different intensities. Scleral crosslinking is known to increase scleral stiffness and may inhibit the axial elongation of progressive myopic eyes. The equatorial parts of the sclera of one eye of six adult albino rabbits were treated with topical riboflavin solution (0.5 %) followed by irradiation with blue light (200, 400, 650 mW/cm(2)) for 20 min. After 3 weeks, the ultrastructure of scleral cells and the abundance of small- (10-100 nm) and large-diameter (>100 nm) collagen fibrils in fibril bundles of different scleral layers were examined with electron microscopy. In the scleral stroma of control eyes, the thickness of collagen fibrils showed a bimodal distribution. The abundance of small-diameter collagen fibrils decreased from the inner towards the outer sclera, while the amount of large-diameter fibrils and the scleral collagen content did not differ between different stroma layers. Treatment with riboflavin and blue light at 200 mW/cm(2) did not induce ultrastructural changes of cells and collagen fibrils in the scleral stroma. Treatment with blue light of higher intensities induced scleral cell activation in a scleral layer-dependent manner. In addition, outer scleral layers contained phagocytes that engulfed collagen fibrils and erythrocytes. Blue light of the highest intensity induced a reduction of the scleral collagen content, a decreased abundance of large-diameter collagen fibrils, and an increased amount of small-diameter fibrils in the whole scleral stroma. The data indicate that in rabbits, scleral crosslinking with riboflavin and blue light of 200 mW/cm(2) for 20 min is relatively safe and does not induce ultrastructural alterations of scleral cells and of the collagen composition of the scleral stroma. Irradiation with blue light of intensities between 200 and 400 mW/cm(2

  1. Peculiarities of light propagation in optically active absorbing crystals of the orthorhombic system

    Science.gov (United States)

    Konstantinova, A. F.; Golovina, T. G.; Nabatov, B. V.; Evdishchenko, E. A.; Konstantinov, K. K.

    2011-05-01

    Peculiarities of the manifestation of optical activity and absorption in crystals of the orthorhombic system of the 222 class are considered. The influence of each effect on the ellipticities of eigenwaves is analyzed. The dependences of the azimuth, ellipticity, and intensity of transmitted light in directions slightly and significantly deviating from the optical axes are considered in detail. Cases are indicated where the approximate relations obtained disregarding multiple reflections and nonorthogonality of eigenwaves in crystal hold true. The differences of the simulated conoscopic patterns of the biaxial absorbing optically active crystals from the patterns of inactive or nonabsorbing crystals are analyzed.

  2. Grey Tienshan Urumqi Glacier No.1 and light-absorbing impurities

    OpenAIRE

    Ming, Jing; Xiao, Cunde; Wang, Feiteng; Li, Zhongqin; Li, Yamin

    2016-01-01

    The Tienshan Urumqi Glacier No.1 (TUG1) usually shows ?grey? surfaces in summers. Besides known regional warming, what should be responsible for largely reducing its surface albedo and making it look ?grey?? A field campaign was conducted on the TUG1 on a selected cloud-free day of 2013 after a snow fall at night. Fresh and aged snow samples were collected in the field, and snow densities, grain sizes, and spectral reflectances were measured. Light-absorbing impurities (LAIs) including black ...

  3. Phototropin 2 is involved in blue light-induced anthocyanin accumulation in Fragaria x ananassa fruits.

    Science.gov (United States)

    Kadomura-Ishikawa, Yasuko; Miyawaki, Katsuyuki; Noji, Sumihare; Takahashi, Akira

    2013-11-01

    Anthocyanins are widespread, essential secondary metabolites in higher plants during color development in certain flowers and fruits. In strawberries, anthocyanins are also key contributors to fruit antioxidant capacity and nutritional value. However, the effects of different light qualities on anthocyanin accumulation in strawberry (Fragaria x ananassa, cv. Sachinoka) fruits remain elusive. In the present study, we showed the most efficient increase in anthocyanin content occurred by blue light irradiation. Light sensing at the molecular level was investigated by isolation of two phototropin (FaPHOT1 and FaPHOT2), two cryptochrome (FaCRY1 and FaCRY2), and two phytochrome (FaPHYA and FaPHYB) homologs. Expression analysis revealed only FaPHOT2 transcripts markedly increased depending on fruit developmental stage, and a corresponding increase in anthocyanin content was detected. FaPHOT2 knockdown resulted in decreased anthocyanin content; however, overexpression increased anthocyanin content. These findings suggested blue light induced anthocyanin accumulation, and FaPHOT2 may play a role in sensing blue light, and mediating anthocyanin biosynthesis in strawberry fruits. This is the first report to find a relationship between visible light sensing, and color development in strawberry fruits.

  4. Intracellular photoreceptive site for blue light-induced cell division in protonemata of the fern Adiantum [Pteridophyta]: Further analyses by polarized light irradiation and cell centrifugation

    International Nuclear Information System (INIS)

    Kadota, A.; Fushimi, Y.; Wada, M.

    1986-01-01

    The intracellular localization of the photoreceptive site for blue light-induced cell division in single-celled protonemata of Adiantum capillus-veneris L. was investigated using polarized light irradiation and protonemal cell centrifugation. The response to irradiation with polarized blue light showed no dependence on the direction of light polarization. However, centrifugation of the protonemata followed by microbeam irradiation showed that the site of blue light perception could be displaced together with the nucleus. Centrifugal treatment changed the distribution of intracellular organelles at the time of light exposure and basipetally displaced the nucleus about 90μm. This treatment had no effect on the induction of cell division with blue light if the protonemata were centrifuged again acropetally after the light treatment. Microbeam (30×30 μm2) irradiation with blue light of the apical 45–75 βm region, the receptive site of blue light in non-centrifuged cell, did not induce cell division. However, cell division was induced by irradiation of the nucleus-containing region, indicating that the photoreceptive site was displaced together with the nucleus by the centrifugation. These results suggest that the blue light receptor regulating cell division in Adiantum protonemata is not likely to be located on the plasma membrane. (author)

  5. Sleep disturbances are related to decreased transmission of blue light to the retina caused by lens yellowing

    DEFF Research Database (Denmark)

    Kessel, Line; Siganos, Galatios; Jørgensen, Torben

    2011-01-01

    Sleep pattern and circadian rhythms are regulated via the retinohypothalamic tract in response to stimulation of a subset of retinal ganglion cells, predominantly by blue light (450-490 nm). With age, the transmission of blue light to the retina is reduced because of the aging process of the human...

  6. The effect of blue light on periodontal biofilm growth in vitro.

    Science.gov (United States)

    Fontana, Carla R; Song, Xiaoqing; Polymeri, Angeliki; Goodson, J Max; Wang, Xiaoshan; Soukos, Nikolaos S

    2015-11-01

    We have previously shown that blue light eliminates the black-pigmented oral bacteria Porphyromonas gingivalis, Prevotella intermedia, Prevotella nigrescens, and Prevotella melaninogenica. In the present study, the in vitro photosensitivity of the above black-pigmented microorganisms and four Fusobacteria species (Fusobacterium nucleatum ss. nucleatum, F. nucleatum ss. vincentii, F. nucleatum ss. polymorphum, Fusobacterium periodonticum) was investigated in pure cultures and human dental plaque suspensions. We also tested the hypothesis that phototargeting the above eight key periodontopathogens in plaque-derived biofilms in vitro would control growth within the dental biofilm environment. Cultures of the eight bacteria were exposed to blue light at 455 nm with power density of 80 mW/cm2 and energy fluence of 4.8 J/cm2. High-performance liquid chromatography (HPLC) analysis of bacteria was performed to demonstrate the presence and amounts of porphyrin molecules within microorganisms. Suspensions of human dental plaque bacteria were also exposed once to blue light at 455 nm with power density of 50 mW/cm2 and energy fluence of 12 J/cm2. Microbial biofilms developed from the same plaque were exposed to 455 nm blue light at 50 mW/cm2 once daily for 4 min (12 J/cm2) over a period of 3 days (4 exposures) in order to investigate the cumulative action of phototherapy on the eight photosensitive pathogens as well as on biofilm growth. Bacterial growth was evaluated using the colony-forming unit (CFU) assay. The selective phototargeting of pathogens was studied using whole genomic probes in the checkerboard DNA-DNA format. In cultures, all eight species showed significant growth reduction (p blue light treatment suppressed biofilm growth in vitro. This may introduce a new avenue of prophylactic treatment for periodontal diseases.

  7. [AOR characterization and zoning: a dosimeter for blue light].

    Science.gov (United States)

    Dario, R; Uva, J; Di Lecce, V; Quarto, A

    2011-01-01

    The paper presents the results obtained thanks to an innovative experimental device for the assessment of artificial optical radiation (AOR) exposure in workplace. This . device was developed by 'Politecnico di Bari-DIASS'. The wearable personal dosimeter has three sensors: one is used for measuring head position/movement, therefore there is a color light sensor to determine the AOR and finally there is a video camera to localize sources. Our system is connected to a netbook via USB cable that allows one to obtain the real and extimated value of worker's exposure, also with "augmented reality". The aim of this paper is realizing work place safety zoning for the classifacation of not only specific dangerous areas through the analysis of overlapping information from the device.

  8. Cryptochrome 1 interacts with PIF4 to regulate high temperature-mediated hypocotyl elongation in response to blue light.

    Science.gov (United States)

    Ma, Dingbang; Li, Xu; Guo, Yongxia; Chu, Jingfang; Fang, Shuang; Yan, Cunyu; Noel, Joseph P; Liu, Hongtao

    2016-01-05

    Cryptochrome 1 (CRY1) is a blue light receptor that mediates primarily blue-light inhibition of hypocotyl elongation. Very little is known of the mechanisms by which CRY1 affects growth. Blue light and temperature are two key environmental signals that profoundly affect plant growth and development, but how these two abiotic factors integrate remains largely unknown. Here, we show that blue light represses high temperature-mediated hypocotyl elongation via CRY1. Furthermore, CRY1 interacts directly with PHYTOCHROME-INTERACTING FACTOR 4 (PIF4) in a blue light-dependent manner to repress the transcription activity of PIF4. CRY1 represses auxin biosynthesis in response to elevated temperature through PIF4. Our results indicate that CRY1 signal by modulating PIF4 activity, and that multiple plant photoreceptors [CRY1 and PHYTOCHROME B (PHYB)] and ambient temperature can mediate morphological responses through the same signaling component-PIF4.

  9. Cryptochrome 1 interacts with PIF4 to regulate high temperature-mediated hypocotyl elongation in response to blue light

    Science.gov (United States)

    Ma, Dingbang; Li, Xu; Guo, Yongxia; Chu, Jingfang; Fang, Shuang; Yan, Cunyu; Noel, Joseph P.; Liu, Hongtao

    2016-01-01

    Cryptochrome 1 (CRY1) is a blue light receptor that mediates primarily blue-light inhibition of hypocotyl elongation. Very little is known of the mechanisms by which CRY1 affects growth. Blue light and temperature are two key environmental signals that profoundly affect plant growth and development, but how these two abiotic factors integrate remains largely unknown. Here, we show that blue light represses high temperature-mediated hypocotyl elongation via CRY1. Furthermore, CRY1 interacts directly with PHYTOCHROME-INTERACTING FACTOR 4 (PIF4) in a blue light-dependent manner to repress the transcription activity of PIF4. CRY1 represses auxin biosynthesis in response to elevated temperature through PIF4. Our results indicate that CRY1 signal by modulating PIF4 activity, and that multiple plant photoreceptors [CRY1 and PHYTOCHROME B (PHYB)] and ambient temperature can mediate morphological responses through the same signaling component—PIF4. PMID:26699514

  10. Combined effects of blue light and supplemental far-red light and effects of increasing red light with constant far-red light on growth of kidney bean [Phaseolus vulgaris] under mixtures of narrow-band light sources

    International Nuclear Information System (INIS)

    Hanyu, H.; Shoji, K.

    2000-01-01

    Increasing blue light and decreasing R: FR with supplementary far-red light affect morphogenesis, dry matter production and dry matter partitioning to leaves, stems and roots. In this study, the combined effects of the two spectral treatments were examined in kidney bean (Phaseolus vulgaris L.) grown under the mixture of four different narrow-band light sources. In addition, because the leaf and stem growth are accelerated by increasing red light (600-700 nm) in proportion to far-red light (700-800 nm) while keeping R : FR constant, this study was conducted to determine whether red light or far-red light causes the acceleration of growth. Increasing blue light (400-500 nm) and decreasing R : FR only interacted on stem extension. The results illustrated with figures suggest that blue light amplifies or attenuates the acceleration of stem extension caused by decreasing R : FR. On the other hand, increasing red light with constant far-red light had no influence on leaf expansion or stem extension while R : FR increased. Because the acceleration of leaf and stem growth is caused by increasing either far-red light or both red and far-red light in our environmental conditions, the stimulative effects on leaves and stems seem to require increases in far-red light rather than red light

  11. Blue-Enriched Morning Light as a Countermeasure to Light at the Wrong Time: Effects on Cognition, Sleepiness, Sleep, and Circadian Phase.

    Science.gov (United States)

    Münch, Mirjam; Nowozin, Claudia; Regente, Johannes; Bes, Frederik; De Zeeuw, Jan; Hädel, Sven; Wahnschaffe, Amely; Kunz, Dieter

    2016-01-01

    Light during the day and darkness at night are crucial factors for proper entrainment of the human circadian system to the solar 24-h day. However, modern life and work styles have led to much more time spent indoors, often with lower daytime and higher evening/nighttime light intensity from electrical lighting than outdoors. Whether this has long-term consequences for human health is being currently investigated. We tested if bright blue-enriched morning light over several days could counteract the detrimental effects of inadequate daytime and evening lighting. In a seminaturalistic, within-between subject study design, 18 young participants were exposed to different lighting conditions on 3 evenings (blue-enriched, bright orange, or dim light), after exposure to 2 lighting conditions (mixed blue-enriched light and control light, for 3 days each) in the mornings. Subjective sleepiness, reaction times, salivary melatonin concentrations, and nighttime sleep were assessed. Exposure to the blue-enriched morning lighting showed acute wake-promoting effects and faster reaction times than with control lighting. Some of these effects persisted until the evening, and performance improved over several days. The magnitude of circadian phase shifts induced by combinations of 3 different evening and 2 morning lighting conditions were significantly smaller with the blue-enriched morning light. During the night, participants had longer total sleep times after orange light exposure than after blue light exposure in the evening. Our results indicate that bright blue-enriched morning light stabilizes circadian phase, and it could be an effective counterstrategy for poor lighting during the day and also light exposure at the wrong time, such as in the late evening. © 2017 S. Karger AG, Basel.

  12. Photodegradation of bisphenol A polycarbonate under blue light radiation and its effect on optical properties

    Science.gov (United States)

    Yazdan Mehr, M.; van Driel, W. D.; Jansen, K. M. B.; Deeben, P.; Boutelje, M.; Zhang, G. Q.

    2013-01-01

    In this investigation, the degradation mechanisms of Bisphenol A Polycarbonate (BPA-PC) plates under blue light radiation are studied. The BPA-PC plates are used both in light conversion carriers in LED modules and encapsulantes in LED packages. Optical degradation of the products is mainly due to the degradation of BPA-PC encapsulants under blue light radiation. In this study, BPA-PC plates are irradiated with blue light at elevated temperature of 140 °C for a period up to 1920 h. Optical and chemical properties of the photo-aged plates were studied using UV-Vis spectrophotometer, FTIR-ATR spectrometer, integrated sphere, and Lambda 950 spectrophotometer. The results show that increasing the exposure time leads to the discoloration, loss of optical properties, decrease of light transmission, decrease in the relative radiant power value, and increase in the yellowing index (YI) of BPA-PC plates. The results also show that there are two stages in the yellowing of polycarbonate plates. The first stage is the so-called induction period in which there is no major change in the value of YI and the rate of yellowing is very slow. This stage takes until 500 h, followed by the second yellowing regime, where the yellowing is accelerated and the rate of yellowing is comparatively faster. Both photo-Fries and photo-oxidation products are identified as the mechanisms of photo-degradation, with photo-Fries predominating as ageing time increases.

  13. Analysis of Pigeon (Columba Ovary Transcriptomes to Identify Genes Involved in Blue Light Regulation.

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    Ying Wang

    Full Text Available Monochromatic light is widely applied to promote poultry reproductive performance, yet little is currently known regarding the mechanism by which light wavelengths affect pigeon reproduction. Recently, high-throughput sequencing technologies have been used to provide genomic information for solving this problem. In this study, we employed Illumina Hiseq 2000 to identify differentially expressed genes in ovary tissue from pigeons under blue and white light conditions and de novo transcriptome assembly to construct a comprehensive sequence database containing information on the mechanisms of follicle development. A total of 157,774 unigenes (mean length: 790 bp were obtained by the Trinity program, and 35.83% of these unigenes were matched to genes in a non-redundant protein database. Gene description, gene ontology, and the clustering of orthologous group terms were performed to annotate the transcriptome assembly. Differentially expressed genes between blue and white light conditions included those related to oocyte maturation, hormone biosynthesis, and circadian rhythm. Furthermore, 17,574 SSRs and 533,887 potential SNPs were identified in this transcriptome assembly. This work is the first transcriptome analysis of the Columba ovary using Illumina technology, and the resulting transcriptome and differentially expressed gene data can facilitate further investigations into the molecular mechanism of the effect of blue light on follicle development and reproduction in pigeons and other bird species.

  14. Distribution of light-absorbing impurities in snow of glacier on Mt. Yulong, southeastern Tibetan Plateau

    Science.gov (United States)

    Niu, Hewen; Kang, Shichang; Zhang, Yulan; Shi, Xiaoyi; Shi, Xiaofei; Wang, Shijin; Li, Gang; Yan, Xingguo; Pu, Tao; He, Yuanqing

    2017-11-01

    Insoluble light-absorbing impurities (ILAIs) in surface snow of glacier reduce snow albedo and accelerate glacier melt. In order to assess effects of ILAIs on glacier melt, we present the first results from field measurements of ILAIs, including black carbon (BC) and dust in snowpacks of glacier on Mt. Yulong, southeastern Tibetan Plateau (TP). Amplification factors because of snow melt were calculated for BC and dust concentrations in surface snow, and melt scavenging rates, effects of ILAIs on snow spectral albedo, and associated radiative forcing (RF) were estimated. Melt amplification generally appeared to be confined to the top few centimeters of the snowpack, and our results indicated that BC was more efficiently scavenged with meltwater than the other insoluble light-absorbers (e.g., dust). Absorbing impurities reduced snow spectral albedo more with larger particulate grain radius (re). Spectral albedo reduction was investigated using the SNow ICe Aerosol Radiative (SNICAR) model. Albedo reduction for 1200 ng g- 1 of BC in Mt. Yulong snow was 0.075 for snow with re = 500 compared with re = 200 μm. If dust (51.37 ppm) was the only impurity in the snowpack, the spectral albedo reduction would be only 0.03, and the associated RF was 42.76 W m- 2. For a BC and dust mixed scenario, the spectral albedo was substantially reduced (0.11 ± 0.03), and the associated RF (145.23 W m- 2) was more than three times larger than that for the dust-only scenario. BC in snow is an active factor controlling snow albedo and snow-ice RF. Further observational studies are needed to quantify the contribution of BC and dust to albedo reduction and glacier melt and to characterize the variation of glacier RF.

  15. Antiproliferative activity of 8-methoxypsoralen on DU145 prostate cancer cells under UVA and blue light.

    Science.gov (United States)

    Sturaro, Giulio; Cigolini, Giulia; Menilli, Luca; Cola, Fabio; Di Liddo, Rosa; Tasso, Alessia; Conconi, Maria Teresa; Miolo, Giorgia

    2017-07-01

    The use of photoactivatable 8-methoxypsoralen (8-MOP) as potential focal treatment towards prostate cancer cells is proposed here. Our results, obtained on isolated DNA and DU145 cells, indicate that blue light, besides UVA, is able to activate 8-MOP. When compared to UVA, blue light irradiation led to a modulation of the extent and the types of 8-MOP-DNA damage, specially cross-links, coupled to a still valuable antiproliferative effect. Our data suggest that the proapototic activity of 8-MOP is related not only to DNA damage and reactive oxygen species generation but also to the modulation of cell signalling pathways. In particular, a different activation of p38 and p44/42 mitogen-activated protein kinases was detected depending on the light wavelengths.

  16. Light-absorbing secondary organic material formed by glyoxal in aqueous aerosol mimics

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    E. L. Shapiro

    2009-04-01

    Full Text Available Light-absorbing and high-molecular-weight secondary organic products were observed to result from the reaction of glyoxal in mildly acidic (pH=4 aqueous inorganic salt solutions mimicking aqueous tropospheric aerosol particles. High-molecular-weight (500–600 amu products were observed when ammonium sulfate ((NH42SO4 or sodium chloride (NaCl was present in the aqueous phase. The products formed in (NH42SO4 or ammonium nitrate (NH4NO3 solutions absorb light at UV and visible wavelengths. Substantial absorption at 300–400 nm develops within two hours, and absorption between 400–600 nm develops within days. Pendant drop tensiometry measurements show that the products are not surface-active. The experimental results along with ab initio predictions of the UV/Vis absorption of potential products suggest a mechanism involving the participation of the ammonium ion. If similar products are formed in atmospheric aerosol particles, they could change the optical properties of the seed aerosol over its lifetime.

  17. Sources of light-absorbing aerosol in arctic snow and their seasonal variation

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    Dean A. Hegg

    2010-11-01

    Full Text Available Two data sets consisting of measurements of light absorbing aerosols (LAA in arctic snow together with suites of other corresponding chemical constituents are presented; the first from Siberia, Greenland and near the North Pole obtained in 2008, and the second from the Canadian arctic obtained in 2009. A preliminary differentiation of the LAA into black carbon (BC and non-BC LAA is done. Source attribution of the light absorbing aerosols was done using a positive matrix factorization (PMF model. Four sources were found for each data set (crop and grass burning, boreal biomass burning, pollution and marine. For both data sets, the crops and grass biomass burning was the main source of both LAA species, suggesting the non-BC LAA was brown carbon. Depth profiles at most of the sites allowed assessment of the seasonal variation in the source strengths. The biomass burning sources dominated in the spring but pollution played a more significant (though rarely dominant role in the fall, winter and, for Greenland, summer. The PMF analysis is consistent with trajectory analysis and satellite fire maps.

  18. Kinetic separation of phototropism from blue-light inhibition of stem elongation

    Science.gov (United States)

    Cosgrove, D. J.

    1985-01-01

    These experiments tested the hypothesis that phototropic bending arises when a light gradient across the stem differentially inhibits cell elongation because of direct inhibition of cell elongation by light (the Blaauw hypothesis). Continuous irradiation of dark-grown cucumber seedlings (Cucumis sativus L.) with unilateral blue light inhibited hypocotyl elongation within 30 s, but did not induce phototropic curvature until 4.5 h after the start of irradiation. Marking experiments showed that curvature began simultaneously at the top and bottom of the growing region. In situ measurements of the light gradient across the stem with a glass fiber optic indicated that a 5- to 6-fold difference in fluence rate was established on the two sides of the stem. The light gradient established at the start of irradiation was the same as that after 6 h of irradiation. Changes in gravitropic responsiveness during this period were also ruled out. Calculations show that the light gradient should have caused curvature which would be detectable within 30 to 60 min and which would extrapolate to the start of irradiation--if the Blaauw hypothesis were correct. The long lag for phototropism in this case indicates that rapid inhibition of cell elongation by blue light does not cause the asymmetrical growth of phototropism. Rather, phototropism is superimposed upon this separate light growth response.

  19. In-car nocturnal blue light exposure improves motorway driving: a randomized controlled trial.

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    Jacques Taillard

    Full Text Available Prolonged wakefulness greatly decreases nocturnal driving performance. The development of in-car countermeasures is a future challenge to prevent sleep-related accidents. The aim of this study is to determine whether continuous exposure to monochromatic light in the short wavelengths (blue light, placed on the dashboard, improves night-time driving performance. In this randomized, double-blind, placebo-controlled, cross-over study, 48 healthy male participants (aged 20-50 years drove 400 km (250 miles on motorway during night-time. They randomly and consecutively received either continuous blue light exposure (GOLite, Philips, 468 nm during driving or 2*200 mg of caffeine or placebo of caffeine before and during the break. Treatments were separated by at least 1 week. The outcomes were number of inappropriate line crossings (ILC and mean standard deviation of the lateral position (SDLP. Eight participants (17% complained about dazzle during blue light exposure and were removed from the analysis. Results from the 40 remaining participants (mean age ± SD: 32.9±11.1 showed that countermeasures reduced the number of inappropriate line crossings (ILC (F(2,91.11 = 6.64; p<0.05. Indeed, ILC were lower with coffee (12.51 [95% CI, 5.86 to 19.66], p = 0.001 and blue light (14.58 [CI, 8.75 to 22.58], p = 0.003 than with placebo (26.42 [CI, 19.90 to 33.71]. Similar results were found for SDLP. Treatments did not modify the quality, quantity and timing of 3 subsequent nocturnal sleep episodes. Despite a lesser tolerance, a non-inferior efficacy of continuous nocturnal blue light exposure compared with caffeine suggests that this in-car countermeasure, used occasionally, could be used to fight nocturnal sleepiness at the wheel in blue light-tolerant drivers, whatever their age. More studies are needed to determine the reproducibility of data and to verify if it can be generalized to women.ClinicalTrials.gov NCT01070004.

  20. Assessment of the potential for resistance to antimicrobial violet-blue light in Staphylococcus aureus

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    Rachael M. Tomb

    2017-09-01

    Full Text Available Abstract Background Antimicrobial violet-blue light in the region of 405 nm is emerging as an alternative technology for hospital decontamination and clinical treatment. The mechanism of action is the excitation of endogenous porphyrins within exposed microorganisms, resulting in ROS generation, oxidative damage and cell death. Although resistance to 405 nm light is not thought likely, little evidence has been published to support this. This study was designed to establish if there is potential for tolerance development, using the nosocomial pathogen Staphylococcus aureus as the model organism. Methods The first stage of this study investigated the potential for S. aureus to develop tolerance to high-intensity 405 nm light if pre-cultured in low-level stress violet-blue light (≤1 mW/cm2 conditions. Secondly, the potential for tolerance development in bacteria subjected to repeated sub-lethal exposure was compared by carrying out 15 cycles of exposure to high-intensity 405 nm light, using a sub-lethal dose of 108 J/cm2. Inactivation kinetics and antibiotic susceptibility were also compared. Results When cultured in low-level violet-blue light conditions, S. aureus required a greater dose of high-intensity 405 nm light for complete inactivation, however this did not increase with multiple (3 low-stress cultivations. Repeated sub-lethal exposures indicated no evidence of bacterial tolerance to 405 nm light. After 15 sub-lethal exposures 1.2 and 1.4 log10 reductions were achieved for MSSA and MRSA respectively, which were not significantly different to the initial 1.3 log10 reductions achieved (P = 0.242 & 0.116, respectively. Antibiotic susceptibility was unaffected, with the maximum change in zone of inhibition being ± 2 mm. Conclusions Repeated sub-lethal exposure of non-proliferating S. aureus populations did not affect the susceptibility of the organism to 405 nm light, nor to antibiotics. Culture in low-level violet-blue light

  1. An Exciplex Host for Deep-Blue Phosphorescent Organic Light-Emitting Diodes.

    Science.gov (United States)

    Lim, Hyoungcheol; Shin, Hyun; Kim, Kwon-Hyeon; Yoo, Seung-Jun; Huh, Jin-Suk; Kim, Jang-Joo

    2017-11-01

    The use of exciplex hosts is attractive for high-performance phosphorescent organic light-emitting diodes (PhOLEDs) and thermally activated delayed fluorescence OLEDs, which have high external quantum efficiency, low driving voltage, and low efficiency roll-off. However, exciplex hosts for deep-blue OLEDs have not yet been reported because of the difficulties in identifying suitable molecules. Here, we report a deep-blue-emitting exciplex system with an exciplex energy of 3.0 eV. It is composed of a carbazole-based hole-transporting material (mCP) and a phosphine-oxide-based electron-transporting material (BM-A10). The blue PhOLEDs exhibited maximum external quantum efficiency of 24% with CIE coordinates of (0.15, 0.21) and longer lifetime than the single host devices.

  2. Immediate effect of blue-enhanced light on reproductive hormones in women.

    Science.gov (United States)

    Danilenko, Konstantin V; Sergeeva, Oksana Y

    2015-01-01

    Light is known to stimulate reproductive function in women. We here investigated the immediate effect of light on reproductive hormones, addressing the role of blue-sensitive (~480 nm) melanopsin-based photoreception mediating the non-visual effects of light. Sixteen healthy women attended the Institute at ~07:25 (shortly after waking; sunglasses worn) twice in 2-3 days in April-May, within days 4-10 of their menstrual cycle. During one session, a broad-spectrum white-appearing light with a superimposed peak at 469 nm was presented against 5-10 lux background; during the other session, short-spectrum red light peaked at 651 nm with similar irradiance level (~7.0 W/m², corresponds to ~1200 lux) was used. Venous blood was taken at 0, 22 and 44 minutes of light exposure to measure concentrations of follicle-stimulating hormone (FSH), luteinising hormone (LH), prolactin, estradiol, progesterone and cortisol, and saliva was sampled to measure melatonin as a recognised indicator of the spectral-specific action of light. Melatonin values, as expected, were lower with white vs. red light (p=0.014), with the greatest difference at 22 minutes. Of the other hormones, only FSH concentrations differed significantly: they were mildly higher at white vs. red light (again, at 22 minutes; p=0.030; statistical analysis adjusted for menstrual cycle day and posture change [pre-sampling time seated]). Moderately bright blue-enhanced white light, compared to matched-by-irradiance red light, transiently (within 22 minutes) and mildly stimulated morning secretion of follicle-stimulating hormone in women in mid-to-late follicular phase of their menstrual cycle suggesting a direct functional link between the light and reproductive system.

  3. The impact of bright artificial white and 'blue-enriched' light on sleep and circadian phase during the polar winter.

    Science.gov (United States)

    Mottram, Victoria; Middleton, Benita; Williams, Peter; Arendt, Josephine

    2011-03-01

    Delayed sleep phase (and sometimes free-run) is common in the Antarctic winter (no natural sunlight) and optimizing the artificial light conditions is desirable. This project evaluated sleep when using 17,000 K blue-enriched lamps compared with standard white lamps (5000 K) for personal and communal illumination. Base personnel, 10 males, five females, 32.5±8 years took part in the study. From 24 March to 21 September 2006 light exposure alternated between 4-5-week periods of standard white (5000 K) and blue-enriched lamps (17,000 K), with a 3-week control before and after extra light. Sleep and light exposure were assessed by actigraphy and sleep diaries. General health (RAND 36-item questionnaire) and circadian phase (urinary 6-sulphatoxymelatonin rhythm) were evaluated at the end of each light condition. Direct comparison (rmanova) of blue-enriched light with white light showed that sleep onset was earlier by 19 min (P=0.022), and sleep latency tended to be shorter by 4 min (P=0.065) with blue-enriched light. Analysing all light conditions, control, blue and white, again provided evidence for greater efficiency of blue-enriched light compared with white (Plight conditions. Circadian phase was earlier on average in midwinter blue compared with midwinter white light by 45 min (PLight condition had no influence on general health. We conclude that the use of blue-enriched light had some beneficial effects, notably earlier sleep, compared with standard white light during the polar winter. © 2010 European Sleep Research Society.

  4. Effects of blue light on gametophyte development of Laminaria japonica (Laminariales, Phaeophyta)

    Science.gov (United States)

    Shi, Cuijuan; Kataoka, Hironao; Duan, Delin

    2005-09-01

    Laminaria gametophyte was greatly influenced by light in its growth and development. Using light-emitting diodes (LED) as blue and red light sources, we analyzed the light effect on gametophytes development of Laminaria japonica Aresch. The gametophytes were obtained from zoospores collected in April, May, July, 2003 and September, 2004. We found that the growth of gametophytes was stimulated by increasing intensity of blue light (BL) and red light (RL) illumination, of which BL was obviously stronger than that of RL. The fertilization of gametophytes depended largely on BL, and only sufficient BL illumination could take the reproductive effect. In addition, we noticed that there was a significant difference in light responses for gametophytes developed from zoospore collected in different times. For zoospores released in April, under BL1 (73.90 μmol photons/m·s), the unicellular female gametophytes and multi-cellular male gametophytes produced eggs and sperms respectively, and further developed towards sporophytes. However, for gametophytes developed in May, July or September, they became multi-cellular and never formed oogonia or antheridia. It is believed that the Laminaria sporangium maturation stage could affect the gametophytes reaction to BL under laboratory culture conditions. Therefore, cryptochrome- or phototropin-like BL photoreceptors is probably involved in BL-induced development of Laminaria gametophytes.

  5. Blue Light Switchable Bacterial Adhesion as a Key Step toward the Design of Biofilms.

    Science.gov (United States)

    Chen, Fei; Wegner, Seraphine V

    2017-12-15

    The control of where and when bacteria adhere to a substrate is a key step toward controlling the formation and organization in biofilms. This study shows how we engineer bacteria to adhere specifically to substrates with high spatial and temporal control under blue light, but not in the dark, by using photoswitchable interaction between nMag and pMag proteins. For this, we express pMag proteins on the surface of E. coli so that the bacteria can adhere to substrates with immobilized nMag protein under blue light. These adhesions are reversible in the dark and can be repeatedly turned on and off. Further, the number of bacteria that can adhere to the substrate as well as the attachment and detachment dynamics are adjustable by using different point mutants of pMag and altering light intensity. Overall, the blue light switchable bacteria adhesions offer reversible, tunable and bioorthogonal control with exceptional spatial and temporal resolution. This enables us to pattern bacteria on substrates with great flexibility.

  6. Blue-light hazard from CO2 arc welding of mild steel.

    Science.gov (United States)

    Okuno, T; Ojima, J; Saito, H

    2010-04-01

    The objective was to quantify the blue-light hazard from CO(2) arc welding of mild steel. The spectral radiance of arcs in CO(2) arc welding of mild steel was measured for solid and flux-cored wires at welding currents of 120-480 A. Effective blue-light radiance and the maximum acceptable exposure duration were calculated from the spectral radiance using their definitions in American Conference of Governmental Industrial Hygienists guidelines. The effective blue-light radiance ranged from 22.9 to 213.1 Wcm(-2)sr(-1). The corresponding maximum acceptable exposure duration was only 0.47-4.36 s, meaning that the total daily exposure to the welding arc without eye protection should not exceed this duration. It is very hazardous to view the arcs in CO(2) arc welding of mild steel. Welders and their helpers should use appropriate eye protectors in these arc-welding operations. Also, they should avoid direct light exposure when starting an arc-welding operation.

  7. Visual function and performance with blue-light blocking filters in age-related macular degeneration.

    Science.gov (United States)

    Kiser, Ava K; Deschler, Emily K; Dagnelie, Gislin

    2008-08-01

    Some dispute has occurred over the use of blue-light-attenuating intraocular lenses in age-related macular degeneration (AMD), as they may reduce scotopic vision. This study aimed to determine if a blue blocking filter would affect performance during eye-hand coordination and mobility tasks in scotopic illumination, psychophysically measured scotopic sensitivity or colour discrimination in AMD patients. Scotopic measures performed with and without a blue-attenuating filter included a mobility obstacle course, manipulation of cylindrical blocks and a psychophysical dark-adapted full-field flash test. A navy and blue sock colour sorting task evaluated photopic colour discrimination. Subjects were 22 bilateral pseudophakes with early AMD and visual acuity >6/24. On average with the filter, there was a 13% increase in time during the block test. The differences in time and number of bumps with versus without the filter were not significant for the mobility course. Performance with and without the filter was well correlated for the blocks (r = 0.70), flash test (r = 0.83) and mobility (r = 0.66), and the regression slopes were not significantly different from unity. 77% of subjects misidentified at least one navy sock as black with the filter compared with 9% without, with a significant increase in such misidentifications with the filter. The difference in scotopic visual function or performance with versus without a blue-blocking filter most likely does not produce a clinically significant effect or risk; however, detection of navy colour may be impaired.

  8. Light-absorbing particulates in seasonal snow in western North America

    Science.gov (United States)

    Dang, Cheng

    Commonly found light-absorbing particulates (LAPs) in snow are black carbon (BC), organic carbon (OC), and mineral dust (MD). These LAPs can reduce the very high albedo of snowpack and trigger positive feedback processes, eventually accelerate the snowmelt and hence influence the climate and hydrology. From the January to March of 2013, a field campaign was conducted to study the LAPs in seasonal snow across 13 American states and 3 Canadian Provinces in western North America. We collected and filtered more than 600 snow samples from 67 sites to extract the water-insoluble LAPs in snow, and saved melted snow samples. More than 500 LAP nuclepore samples were analyzed in a spectrophotometer to estimate the light absorption due to LAP samples. This optical analysis also allow us to calculate the absorption Angstrom exponent (A) of LAPs, estimate the BC mixing ratio, and partition the light absorption by BC and non-BC LAPs. About 100 LAP GHP samples were extracted by a serial of chemical solvents to remove OC; then measured in the spectrophotometer to estimate the light absorption changes. The iron concentration was derived from ICP-MS (Inductively Coupled Plasma - Mass Spectroscopy), and was used to estimate the light absorption due to MD. The BC mixing ratio varies from 4--510 ng/g (ng of BC/g of snow), with regional medians vary from 14 ng/g in the Pacific Northwest to 65 ng/g in the Northern Plains. This amount of BC is lower than that found in China, and the LAP in the cleanest sites is as low as that found in the Arctic snow. The regional medians of A vary from 1.6 to 2.6, indicating that BC is not the only LAP in snow. Chemical extractions suggest that methanol-soluble OC (polar OC) and base-soluble HULIS are responsible for 3% and 8% of light absorption by all LAP respectively. They are likely generated from biomass burning or soil. The fractional light absorption produced by OC and HULIS in the Northern Plains is a factor of two higher than that of the other

  9. Transcriptome Analysis Reveals that Red and Blue Light Regulate Growth and Phytohormone Metabolism in Norway Spruce [Picea abies (L.) Karst].

    Science.gov (United States)

    OuYang, Fangqun; Mao, Jian-Feng; Wang, Junhui; Zhang, Shougong; Li, Yue

    2015-01-01

    The mechanisms by which different light spectra regulate plant shoot elongation vary, and phytohormones respond differently to such spectrum-associated regulatory effects. Light supplementation can effectively control seedling growth in Norway spruce. However, knowledge of the effective spectrum for promoting growth and phytohormone metabolism in this species is lacking. In this study, 3-year-old Norway spruce clones were illuminated for 12 h after sunset under blue or red light-emitting diode (LED) light for 90 d, and stem increments and other growth traits were determined. Endogenous hormone levels and transcriptome differences in the current needles were assessed to identify genes related to the red and blue light regulatory responses. The results showed that the stem increment and gibberellin (GA) levels of the seedlings illuminated by red light were 8.6% and 29.0% higher, respectively, than those of the seedlings illuminated by blue light. The indoleacetic acid (IAA) level of the seedlings illuminated by red light was 54.6% lower than that of the seedlings illuminated by blue light, and there were no significant differences in abscisic acid (ABA) or zeatin riboside [ZR] between the two groups of seedlings. The transcriptome results revealed 58,736,166 and 60,555,192 clean reads for the blue-light- and red-light-illuminated samples, respectively. Illumina sequencing revealed 21,923 unigenes, and 2744 (approximately 93.8%) out of 2926 differentially expressed genes (DEGs) were found to be upregulated under blue light. The main KEGG classifications of the DEGs were metabolic pathway (29%), biosynthesis of secondary metabolites (20.49%) and hormone signal transduction (8.39%). With regard to hormone signal transduction, AUXIN-RESISTANT1 (AUX1), AUX/IAA genes, auxin-inducible genes, and early auxin-responsive genes [(auxin response factor (ARF) and small auxin-up RNA (SAUR)] were all upregulated under blue light compared with red light, which might have yielded the

  10. Transcriptome Analysis Reveals that Red and Blue Light Regulate Growth and Phytohormone Metabolism in Norway Spruce [Picea abies (L. Karst].

    Directory of Open Access Journals (Sweden)

    Fangqun OuYang

    Full Text Available The mechanisms by which different light spectra regulate plant shoot elongation vary, and phytohormones respond differently to such spectrum-associated regulatory effects. Light supplementation can effectively control seedling growth in Norway spruce. However, knowledge of the effective spectrum for promoting growth and phytohormone metabolism in this species is lacking. In this study, 3-year-old Norway spruce clones were illuminated for 12 h after sunset under blue or red light-emitting diode (LED light for 90 d, and stem increments and other growth traits were determined. Endogenous hormone levels and transcriptome differences in the current needles were assessed to identify genes related to the red and blue light regulatory responses. The results showed that the stem increment and gibberellin (GA levels of the seedlings illuminated by red light were 8.6% and 29.0% higher, respectively, than those of the seedlings illuminated by blue light. The indoleacetic acid (IAA level of the seedlings illuminated by red light was 54.6% lower than that of the seedlings illuminated by blue light, and there were no significant differences in abscisic acid (ABA or zeatin riboside [ZR] between the two groups of seedlings. The transcriptome results revealed 58,736,166 and 60,555,192 clean reads for the blue-light- and red-light-illuminated samples, respectively. Illumina sequencing revealed 21,923 unigenes, and 2744 (approximately 93.8% out of 2926 differentially expressed genes (DEGs were found to be upregulated under blue light. The main KEGG classifications of the DEGs were metabolic pathway (29%, biosynthesis of secondary metabolites (20.49% and hormone signal transduction (8.39%. With regard to hormone signal transduction, AUXIN-RESISTANT1 (AUX1, AUX/IAA genes, auxin-inducible genes, and early auxin-responsive genes [(auxin response factor (ARF and small auxin-up RNA (SAUR] were all upregulated under blue light compared with red light, which might have

  11. Phosphorescent cyclometalated complexes for efficient blue organic light-emitting diodes.

    Science.gov (United States)

    Suzuri, Yoshiyuki; Oshiyama, Tomohiro; Ito, Hiroto; Hiyama, Kunihisa; Kita, Hiroshi

    2014-10-01

    Phosphorescent emitters are extremely important for efficient organic light-emitting diodes (OLEDs), which attract significant attention. Phosphorescent emitters, which have a high phosphorescence quantum yield at room temperature, typically contain a heavy metal such as iridium and have been reported to emit blue, green and red light. In particular, the blue cyclometalated complexes with high efficiency and high stability are being developed. In this review, we focus on blue cyclometalated complexes. Recent progress of computational analysis necessary to design a cyclometalated complex is introduced. The prediction of the radiative transition is indispensable to get an emissive cyclometalated complex. We summarize four methods to control phosphorescence peak of the cyclometalated complex: (i) substituent effect on ligands, (ii) effects of ancillary ligands on heteroleptic complexes, (iii) design of the ligand skeleton, and (iv) selection of the central metal. It is considered that novel ligand skeletons would be important to achieve both a high efficiency and long lifetime in the blue OLEDs. Moreover, the combination of an emitter and a host is important as well as the emitter itself. According to the dependences on the combination of an emitter and a host, the control of exciton density of the triplet is necessary to achieve both a high efficiency and a long lifetime, because the annihilations of the triplet state cause exciton quenching and material deterioration.

  12. Efficient charge balance in blue phosphorescent organic light emitting diodes by two types of mixed layer

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Hyung Jin; Lee, Ho Won; Lee, Song Eun; Sun, Yong; Hwang, Kyo Min; Yoo, Han Kyu; Lee, Sung Kyu [Department of Information Display, Hongik University, Seoul 121-791 (Korea, Republic of); Kim, Woo Young, E-mail: wykim@hoseo.edu [Department of Green Energy & Semiconductor Engineering, Hoseo University, Asan 336-795 (Korea, Republic of); Kim, Young Kwan, E-mail: kimyk@hongik.ac.kr [Department of Information Display, Hongik University, Seoul 121-791 (Korea, Republic of)

    2015-07-31

    The authors have demonstrated a highly efficient and long-lifetime blue phosphorescent organic light emitting diode (PHOLED) that uses two types of mixed layers. The mixed layers play the role of carrier injection control and exciton generation zone extension. One of the layers is applied for mixing the hole transport layer (HTL) and host material at the HTL side for carrier injection control. The other works as a mixed electron transporting layer (ETL) and host material at the ETL side. The optimized blue PHOLED has been shown to achieve high performance owing to the mixed layer effects. It gave a maximum luminous efficiency of 25.55 cd/A, maximum external quantum efficiency of 13.05%, and lifetime of 7.24 h under 500 cd/m{sup 2}. These results indicate that applying mixed layers is a simple and efficient method that does not require significant structural change. - Highlights: • Highly efficient blue phosphorescent organic light-emitting diode (PHOLEDs) • Hole transporting layer consists with mixed layer for delayed hole injection • The blue PHOLEDs with long lifetime due to suppression of quenching process.

  13. Staring at the cold sun: blue light regulation is distributed within the genus Acinetobacter.

    Directory of Open Access Journals (Sweden)

    Adrián Golic

    Full Text Available We previously showed that the opportunistic nosocomial pathogen Acinetobacter baumannii is able to sense and respond to light via BlsA, a BLUF (Blue-Light-sensing Using FAD-domain photoreceptor protein. Here, we extend our previous studies showing that light regulation is not restricted to A. baumannii, but rather widespread within the genus Acinetobacter. First, we found that blue light modulates motility and biofilm formation in many species of the genus, including members of the Acinetobacter calcoaceticus-A. baumannii complex. In many of these species blue light acts as a key factor guiding the decision between motility or sessility at 24°C, whereas in A. baumannii, light inhibits both motility and biofilm formation. We also show that light regulation of motility occurred not only at 24°C but also at 37°C in non-A. baumannii species, contrasting the situation of A. baumannii which only shows photoregulation at 24°C. Second, we show that Acinetobacter baylyi (strain ADP1 BLUF-photoreceptors can functionally replace in vivo the A. baumannii 17978 BlsA protein and that the pathways leading to biofilm formation are inversely regulated at 24°C between these two microorganisms. Finally, we found the presence of predicted genes coding BLUF-containing proteins in all Acinetobacter sequenced genomes, even though the copy number is variable among them. Phylogenetic analysis suggests a common origin for all BLUF domains present in members of this genus, and could distinguish well-differentiated clusters that group together BLUF homologs from different species, a situation particularly clear for members of the ACB complex. Despite a role played by these BLUF domain-containing proteins in the photoregulation observed in the members of the genus Acinetobacter is a likely scenario given our findings in A. baumannii and A. baylyi, further research will contribute to confirm this possibility.

  14. Staring at the Cold Sun: Blue Light Regulation Is Distributed within the Genus Acinetobacter

    Science.gov (United States)

    Golic, Adrián; Vaneechoutte, Mario; Nemec, Alexandr; Viale, Alejandro M.; Actis, Luis A.; Mussi, María Alejandra

    2013-01-01

    We previously showed that the opportunistic nosocomial pathogen Acinetobacter baumannii is able to sense and respond to light via BlsA, a BLUF (Blue-Light-sensing Using FAD)-domain photoreceptor protein. Here, we extend our previous studies showing that light regulation is not restricted to A. baumannii, but rather widespread within the genus Acinetobacter. First, we found that blue light modulates motility and biofilm formation in many species of the genus, including members of the Acinetobacter calcoaceticus-A. baumannii complex. In many of these species blue light acts as a key factor guiding the decision between motility or sessility at 24°C, whereas in A. baumannii, light inhibits both motility and biofilm formation. We also show that light regulation of motility occurred not only at 24°C but also at 37°C in non-A. baumannii species, contrasting the situation of A. baumannii which only shows photoregulation at 24°C. Second, we show that Acinetobacter baylyi (strain ADP1) BLUF-photoreceptors can functionally replace in vivo the A. baumannii 17978 BlsA protein and that the pathways leading to biofilm formation are inversely regulated at 24°C between these two microorganisms. Finally, we found the presence of predicted genes coding BLUF-containing proteins in all Acinetobacter sequenced genomes, even though the copy number is variable among them. Phylogenetic analysis suggests a common origin for all BLUF domains present in members of this genus, and could distinguish well-differentiated clusters that group together BLUF homologs from different species, a situation particularly clear for members of the ACB complex. Despite a role played by these BLUF domain-containing proteins in the photoregulation observed in the members of the genus Acinetobacter is a likely scenario given our findings in A. baumannii and A. baylyi, further research will contribute to confirm this possibility. PMID:23358859

  15. Blue-enriched white light in the workplace improves self-reported alertness, performance and sleep quality.

    Science.gov (United States)

    Viola, Antoine U; James, Lynette M; Schlangen, Luc J M; Dijk, Derk-Jan

    2008-08-01

    Specifications and standards for lighting installations in occupational settings are based on the spectral sensitivity of the classical visual system and do not take into account the recently discovered melanopsin-based, blue-light-sensitive photoreceptive system. The authors investigated the effects of exposure to blue-enriched white light during daytime workhours in an office setting. The experiment was conducted on 104 white-collar workers on two office floors. After baseline assessments under existing lighting conditions, every participant was exposed to two new lighting conditions, each lasting 4 weeks. One consisted of blue-enriched white light (17 000 K) and the other of white light (4000 K). The order was balanced between the floors. Questionnaire and rating scales were used to assess alertness, mood, sleep quality, performance, mental effort, headache and eye strain, and mood throughout the 8-week intervention. Altogether 94 participants [mean age 36.4 (SD 10.2) years] were included in the analysis. Compared with white light (4000 K), blue-enriched white light (17 000 K) improved the subjective measures of alertness (Pblue-enriched white light. When the participants' expectation about the effect of the light treatments was entered into the analysis as a covariate, significant effects persisted for performance, alertness, evening fatigue, irritability, difficulty focusing, concentrating, and blurred vision. Exposure to blue-enriched white light during daytime workhours improves subjective alertness, performance, and evening fatigue.

  16. Antimicrobial blue light inactivation of Pseudomonas aeruginosa by photo-excitation of endogenous porphyrins: In vitro and in vivo studies.

    Science.gov (United States)

    Amin, Rehab M; Bhayana, Brijesh; Hamblin, Michael R; Dai, Tianhong

    2016-07-01

    Pseudomonas aeruginosa is among the most common pathogens that cause nosocomial infections and is responsible for about 10% of all hospital-acquired infections. In the present study, we investigated the potential development of tolerance of P. aeruginosa to antimicrobial blue light by carrying 10 successive cycles of sublethal blue light inactivation. The high-performance liquid chromatographic (HPLC) analysis was performed to identify endogenous porphyrins in P. aeruginosa cells. In addition, we tested the effectiveness of antimicrobial blue light in a mouse model of nonlethal skin abrasion infection by using a bioluminescent strain of P. aeruginosa. The results demonstrated that no tolerance was developed to antimicrobial blue light in P. aeruginosa after 10 cycles of sub-lethal inactivation. HPLC analysis showed that P. aeruginosa is capable of producing endogenous porphyrins in particularly, coproporphyrin III, which are assumed to be responsible for the photodynamic effects of blue light alone. P. aeruginosa infection was eradicated by antimicrobial blue light alone (48 J/cm(2) ) without any added photosensitizer molecules in the mouse model. In conclusion, endogenous photosensitization using blue light should gain considerable attention as an effective and safe alternative antimicrobial therapy for skin infections. Lasers Surg. Med. 48:562-568, 2016. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

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

    CERN Document Server

    MacKinlay, Alistair F; Whillock, M J

    1989-01-01

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

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

    Science.gov (United States)

    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.

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

    Energy Technology Data Exchange (ETDEWEB)

    Caldwell, M.M.; Flint, S.D. [Utah State Univ., Logan, UT (United States)

    1994-12-31

    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.

  20. Influence of Pre-trimethylindium flow treatment on blue light emitting diode

    International Nuclear Information System (INIS)

    Xu, Bing; Zhao, Jun Liang; Dai, Hai Tao; Wang, Shu Guo; Lin, Ray-Ming; Chu, Fu-Chuan; Huang, Chou-Hsiung; Yu, Sheng-Fu; Sun, Xiao Wei

    2014-01-01

    The effects of Pre-trimethylindium (TMIn) flow treatment prior to quantum well growth on blue light emitting diode properties were investigated. High-resolution X-ray diffraction indicated that Pre-TMIn flow treatment did not change the composition of indium in quantum wells, but influenced electrical and optical properties of blue light emitting diode. Electroluminescence exhibited redshift with increasing TMIn treatment time. Though, the forward voltage became a little larger with longer Pre-TMIn treatment time due to the slight phase separation and indium aggregation, the efficiency droop of the device was improved effectively. - Highlights: • Pre-trimethylindium treatment can lead to longer wavelength. • External quantum efficiency can be improved effectively. • Electrical properties are not decreased using Pre-trimethylindium treatment

  1. Influence of Pre-trimethylindium flow treatment on blue light emitting diode

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Bing; Zhao, Jun Liang [Tianjin Key Laboratory of Low Dimensional Materials Physics and Preparing Technology, School of Science, Tianjin University, Tianjin 300072 (China); Dai, Hai Tao, E-mail: htdai@tju.edu.cn [Tianjin Key Laboratory of Low Dimensional Materials Physics and Preparing Technology, School of Science, Tianjin University, Tianjin 300072 (China); Wang, Shu Guo [Tianjin Key Laboratory of Low Dimensional Materials Physics and Preparing Technology, School of Science, Tianjin University, Tianjin 300072 (China); Lin, Ray-Ming, E-mail: rmlin@mail.cgu.edu.tw [Graduate Institute of Electronic Engineering and Green Technology Research Center, Chang Gung University, Taoyuan 333, Taiwan (China); Chu, Fu-Chuan; Huang, Chou-Hsiung [Graduate Institute of Electronic Engineering and Green Technology Research Center, Chang Gung University, Taoyuan 333, Taiwan (China); Yu, Sheng-Fu [Institute of Microelectronics and Department of Electrical Engineering, Center for Micro/Nano Science and Technology, Advanced Optoelectronic Technology Center, National Cheng Kung University, Tainan 70101, Taiwan (China); Sun, Xiao Wei, E-mail: xwsun@sustc.edu.cn [South University of Science and Technology of China, Shenzhen, Guangdong (China)

    2014-01-31

    The effects of Pre-trimethylindium (TMIn) flow treatment prior to quantum well growth on blue light emitting diode properties were investigated. High-resolution X-ray diffraction indicated that Pre-TMIn flow treatment did not change the composition of indium in quantum wells, but influenced electrical and optical properties of blue light emitting diode. Electroluminescence exhibited redshift with increasing TMIn treatment time. Though, the forward voltage became a little larger with longer Pre-TMIn treatment time due to the slight phase separation and indium aggregation, the efficiency droop of the device was improved effectively. - Highlights: • Pre-trimethylindium treatment can lead to longer wavelength. • External quantum efficiency can be improved effectively. • Electrical properties are not decreased using Pre-trimethylindium treatment.

  2. Applications of Blue Light-curing Acrylic Resin to Forensic Sample Preparation and Microtomy.

    Science.gov (United States)

    Groves, Ethan; Palenik, Christopher S

    2016-03-01

    This study discusses the results of an evaluation of a one-part blue light-curing acrylic resin for embedding trace evidence prior to the preparation of thin sections with a microtome. Through a comparison to several epoxy resins, the physical properties relevant to both trace evidence examination and analytical microscopy in general, including as viscosity, clarity, color, hardness, and cure speed, were explored. Finally, thin sections from paint samples embedded in this acrylic resin were evaluated to determine if, through smearing or impregnation, the resin contributed to the infrared spectra. The results of this study show that blue light-curing acrylic resins provide the desired properties of an embedding medium, generate high-quality thin sections, and can significantly simplify the preparation of paint chips, fibers and a multitude of other types of microscopic samples in the forensic trace evidence laboratory. © 2015 American Academy of Forensic Sciences.

  3. Investigating fibroblast cells under "safe" and "injurious" blue-light exposure by holographic microscopy.

    Science.gov (United States)

    Calabuig, Alejandro; Mugnano, Martina; Miccio, Lisa; Grilli, Simonetta; Ferraro, Pietro

    2017-06-01

    The exposure to visible light has been shown to exert various biological effects, such as erythema and retinal degeneration. However, the phototoxicity mechanisms in living cells are still not well understood. Here we report a study on the temporal evolution of cell morphology and volume during blue light exposure. Blue laser irradiation is switched during the operation of a digital holography (DH) microscope between what we call here "safe" and "injurious" exposure (SE & IE). The results reveal a behaviour that is typical of necrotic cells, with early swelling and successive leakage of the intracellular liquids when the laser is set in the "injurious" operation. In the phototoxicity investigation reported here the light dose modulation is performed through the very same laser light source adopted for monitoring the cell's behaviour by digital holographic microscope. We believe the approach may open the route to a deep investigation of light-cell interactions, with information about death pathways and threshold conditions between healthy and damaged cells when subjected to light-exposure. 3D Morphology and quantitative phase information from late stage of necrosis cell death. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

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

    Science.gov (United States)

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

    2013-01-01

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

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

    Science.gov (United States)

    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. The effects of low-intensity narrow-band blue-light treatment compared to bright white-light treatment in sub-syndromal seasonal affective disorder.

    Science.gov (United States)

    Meesters, Ybe; Winthorst, Wim H; Duijzer, Wianne B; Hommes, Vanja

    2016-02-18

    The discovery of a novel photoreceptor in the retinal ganglion cells with a highest sensitivity of 470-490 nm blue light has led to research on the effects of short-wavelength light in humans. Several studies have explored the efficacy of monochromatic blue or blue-enriched light in the treatment of SAD. In this study, a comparison has been made between the effects of broad-wavelength light without ultraviolet (UV) wavelengths compared to narrow-band blue light in the treatment of sub-syndromal seasonal affective disorder (Sub-SAD). In a 15-day design, 48 participants suffering from Sub-SAD completed 20-minute sessions of light treatment on five consecutive days. 22 participants were given bright white-light treatment (BLT, broad-wavelength light without UV 10 000 lux, irradiance 31.7 Watt/m(2)) and 26 participants received narrow-band blue light (BLUE, 100 lux, irradiance 1.0 Watt/m(2)). All participants completed daily and weekly questionnaires concerning mood, activation, sleep quality, sleepiness and energy. Also, mood and energy levels were assessed by means of the SIGH-SAD, the primary outcome measure. On day 15, SIGH-SAD ratings were significantly lower than on day 1 (BLT 54.8 %, effect size 1.7 and BLUE 50.7 %, effect size 1.9). No statistically significant differences were found on the main outcome measures. Light treatment is an effective treatment for Sub-SAD. The use of narrow-band blue-light treatment is equally effective as bright white-light treatment. This study was registered in the Dutch Trial Register (Nederlands Trial Register TC =  4342 ) (20-12-2013).

  7. Spontaneous mutation 7B-1 in tomato impairs blue light-induced stomatal opening

    Czech Academy of Sciences Publication Activity Database

    Hlavinka, J.; Nauš, J.; Fellner, Martin

    2013-01-01

    Roč. 209, č. 2013 (2013), s. 75-80 ISSN 0168-9452 R&D Projects: GA ČR GD522/08/H003 Grant - others:GA ČR(CZ) GAP501/10/0785 Program:GA Institutional research plan: CEZ:AV0Z50380511 Keywords : ABA * Anion-channel blocker * Blue light Subject RIV: ED - Physiology Impact factor: 4.114, year: 2013

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

    OpenAIRE

    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...

  9. Highly predictable photosynthetic production in natural macroalgal communities from incoming and absorbed light

    DEFF Research Database (Denmark)

    Middelboe, Anne Lise; Sand-Jensen, Kaj; Binzer, Thomas

    2006-01-01

    Photosynthesis-irradiance relationships of macroalgal communities and thalli of dominant species in shallow coastal Danish waters were measured over a full year to test how well community production can be predicted from environmental (incident irradiance and temperature) and community variables...... and was unrelated to incident irradiance, temperature and mean thallus photosynthesis, while community absorptance was a highly significant predictor. Actual rates of community photosynthesis were closely related to incident and absorbed irradiance alone. Community absorptance in turn was correlated to canopy...... (canopy absorptance, species number and thallus metabolism). Detached thalli of dominant species performed optimally at different times of the year, but showed no general seasonal changes in photosynthetic features. Production capacity of communities at high light varied only 1.8-fold over the year...

  10. Modelling hydrologic impacts of light absorbing aerosol deposition on snow at the catchment scale

    Science.gov (United States)

    Matt, Felix N.; Burkhart, John F.; Pietikäinen, Joni-Pekka

    2018-01-01

    Light absorbing impurities in snow and ice (LAISI) originating from atmospheric deposition enhance snowmelt by increasing the absorption of shortwave radiation. The consequences are a shortening of the snow duration due to increased snowmelt and, at the catchment scale, a temporal shift in the discharge generation during the spring melt season. In this study, we present a newly developed snow algorithm for application in hydrological models that allows for an additional class of input variable: the deposition mass flux of various species of light absorbing aerosols. To show the sensitivity of different model parameters, we first use the model as a 1-D point model forced with representative synthetic data and investigate the impact of parameters and variables specific to the algorithm determining the effect of LAISI. We then demonstrate the significance of the radiative forcing by simulating the effect of black carbon (BC) deposited on snow of a remote southern Norwegian catchment over a 6-year period, from September 2006 to August 2012. Our simulations suggest a significant impact of BC in snow on the hydrological cycle. Results show an average increase in discharge of 2.5, 9.9, and 21.4 %, depending on the applied model scenario, over a 2-month period during the spring melt season compared to simulations where radiative forcing from LAISI is not considered. The increase in discharge is followed by a decrease in discharge due to a faster decrease in the catchment's snow-covered fraction and a trend towards earlier melt in the scenarios where radiative forcing from LAISI is applied. Using a reasonable estimate of critical model parameters, the model simulates realistic BC mixing ratios in surface snow with a strong annual cycle, showing increasing surface BC mixing ratios during spring melt as a consequence of melt amplification. However, we further identify large uncertainties in the representation of the surface BC mixing ratio during snowmelt and the subsequent

  11. White- and blue-light-emitting dysprosium(III) and terbium(III)-doped gadolinium titanate phosphors.

    Science.gov (United States)

    Antić, Ž; Kuzman, S; Đorđević, V; Dramićanin, M D; Thundat, T

    2017-06-01

    Here we report the synthesis and structural, morphological, and photoluminescence analysis of white- and blue-light-emitting Dy 3 + - and Tm 3 + -doped Gd 2 Ti 2 O 7 nanophosphors. Single-phase cubic Gd 2 Ti 2 O 7 nanopowders consist of compact, dense aggregates of nanoparticles with an average size of ~25 nm for Dy 3 + -doped and ~50 nm for Tm 3 + -doped samples. The photoluminescence results indicated that ultraviolet (UV) light excitation of the Dy 3 + -doped sample resulted in direct generation of white light, while a dominant yellow emission was obtained under blue-light excitation. Intense blue light was obtained for Tm 3 + -doped Gd 2 Ti 2 O 7 under UV excitation suggesting that this material could be used as a blue phosphor. Copyright © 2016 John Wiley & Sons, Ltd.

  12. Short Blue Light Pulses (30 Min) in the Morning Support a Sleep-Advancing Protocol in a Home Setting.

    Science.gov (United States)

    Geerdink, Moniek; Walbeek, Thijs J; Beersma, Domien G M; Hommes, Vanja; Gordijn, Marijke C M

    2016-10-01

    Many people in our modern civilized society sleep later on free days compared to work days. This discrepancy in sleep timing will lead to so-called 'social jetlag' on work days with negative consequences for performance and health. Light therapy in the morning is often proposed as the most effective method to advance the circadian rhythm and sleep phase. However, most studies focus on direct effects on the circadian system and not on posttreatment effects on sleep phase and sleep integrity. In this placebo-controlled home study we investigated if blue light, rather than amber light therapy, can phase shift the sleep phase along with the circadian rhythm with preservation of sleep integrity and performance. We selected 42 participants who suffered from 'social jetlag' on workdays. Participants were randomly assigned to either high-intensity blue light exposure or amber light exposure (placebo) with similar photopic illuminance. The protocol consisted of 14 baseline days without sleep restrictions, 9 treatment days with either 30-min blue light pulses or 30-min amber light pulses in the morning along with a sleep advancing scheme and 7 posttreatment days without sleep restrictions. Melatonin samples were taken at days 1, 7, 14 (baseline), day 23 (effect treatment), and day 30 (posttreatment). Light exposure was recorded continuously. Sleep was monitored through actigraphy. Performance was measured with a reaction time task. As expected, the phase advance of the melatonin rhythm from day 14 to day 23 was significantly larger in the blue light exposure group, compared to the amber light group (84 min ± 51 (SD) and 48 min ± 47 (SD) respectively; t36 = 2.23, p blue light group compared to slightly later in the amber light group (-21 min ± 33 (SD) and +12 min ± 33 (SD) respectively; F1,35 = 9.20, p light group compared to the blue light group during sleep in the treatment period (F1,32 = 4.40, p light treatment (F1,13 = 17.1, p blue light

  13. The evolution of flavin-binding photoreceptors: an ancient chromophore serving trendy blue-light sensors.

    Science.gov (United States)

    Losi, Aba; Gärtner, Wolfgang

    2012-01-01

    Photoreceptor flavoproteins of the LOV, BLUF, and cryptochrome families are ubiquitous among the three domains of life and are configured as UVA/blue-light systems not only in plants-their original arena-but also in prokaryotes and microscopic algae. Here, we review these proteins' structure and function, their biological roles, and their evolution and impact in the living world, and underline their growing application in biotechnologies. We present novel developments such as the interplay of light and redox stimuli, emerging enzymatic and biological functions, lessons on evolution from picoalgae, metagenomics analysis, and optogenetics applications.

  14. The Plasma Membrane H+-ATPase AHA1 Plays a Major Role in Stomatal Opening in Response to Blue Light.

    Science.gov (United States)

    Yamauchi, Shota; Takemiya, Atsushi; Sakamoto, Tomoaki; Kurata, Tetsuya; Tsutsumi, Toshifumi; Kinoshita, Toshinori; Shimazaki, Ken-Ichiro

    2016-08-01

    Stomata open in response to a beam of weak blue light under strong red light illumination. A blue light signal is perceived by phototropins and transmitted to the plasma membrane H(+)-ATPase that drives stomatal opening. To identify the components in this pathway, we screened for mutants impaired in blue light-dependent stomatal opening. We analyzed one such mutant, provisionally named blus2 (blue light signaling2), and found that stomatal opening in leaves was impaired by 65%, although the magnitude of red light-induced opening was not affected. Blue light-dependent stomatal opening in the epidermis and H(+) pumping in guard cell protoplasts were inhibited by 70% in blus2 Whole-genome resequencing identified a mutation in the AHA1 gene of the mutant at Gly-602. T-DNA insertion mutants of AHA1 exhibited a similar phenotype to blus2; this phenotype was complemented by the AHA1 gene. We renamed blus2 as aha1-10 T-DNA insertion mutants of AHA2 and AHA5 did not show any impairment in stomatal response, although the transcript levels of AHA2 and AHA5 were higher than those of AHA1 in wild-type guard cells. Stomata in ost2, a constitutively active AHA1 mutant, did not respond to blue light. A decreased amount of H(+)-ATPase in aha1-10 accounted for the reduced stomatal blue light responses and the decrease was likely caused by proteolysis of misfolded AHA1. From these results, we conclude that AHA1 plays a major role in blue light-dependent stomatal opening in Arabidopsis and that the mutation made the AHA1 protein unstable in guard cells. © 2016 American Society of Plant Biologists. All Rights Reserved.

  15. Facilitation of creative performance by using blue and red accent lighting in work and learning areas.

    Science.gov (United States)

    Kombeiz, Olga; Steidle, Anna

    2018-03-01

    Research has shown that colours influence motivation and cognitive performance. In achievement contexts, red evokes avoidance motivation that hinders creativity, while blue elicits an approach motivation that facilitates creativity. However, due to their position and mode of presentation, colours may convey a different message. Red accent lighting creates a cosy, friendly room atmosphere that may, even in an achievement context, elicit an approach rather than an avoidance motivation. Results (N = 146) showed that both blue and red accent light increased strategic approach motivation compared to white accent light. Moreover, through the heightened approach motivation, colourful accent light indirectly improved creative performance. Implications for future research on colour and practical implications for colour usage are discussed. Practitioner Summary: Designing work environments for creativity is a new topic in ergonomics research and practice. The present study demonstrates indirect effects of coloured accent light on creativity providing interesting possibilities for the design of workplaces for knowledge workers, classrooms and all other rooms in which people work on new ideas.

  16. 4-Gbit/s visible light communication link based on 16-QAM OFDM transmission over remote phosphor-film converted white light by using blue laser diode

    KAUST Repository

    Duran Retamal, Jose Ramon

    2015-12-21

    Visible Light Communication (VLC) as a new technology for ultrahigh-speed communication is still limited when using slow modulation light-emitting diode (LED). Alternatively, we present a 4-Gbit/s VLC system using coherent blue-laser diode (LD) via 16-quadrature amplitude modulation orthogonal frequency division multiplexing. By changing the composition and the optical-configuration of a remote phosphor-film the generated white light is tuned from cool day to neutral, and the bit error rate is optimized from 1.9 × 10-2 to 2.8 × 10-5 in a blue filter-free link due to enhanced blue light transmission in forward direction. Briefly, blue-LD is an alternative to LED for generating white light and boosting the data rate of VLC. © 2015 Optical Society of America.

  17. Comparison between red, green and blue light reflection photoplethysmography for heart rate monitoring during motion.

    Science.gov (United States)

    Lee, Jihyoung; Matsumura, Kenta; Yamakoshi, Ken-ichi; Rolfe, Peter; Tanaka, Shinobu; Yamakoshi, Takehiro

    2013-01-01

    Reflection photoplethysmography (PPG) using 530 nm (green) wavelength light has the potential to be a superior method for monitoring heart rate (HR) during normal daily life due to its relative freedom from artifacts. However, little is known about the accuracy of pulse rate (PR) measured by 530 nm light PPG during motion. Therefore, we compared the HR measured by electrocadiography (ECG) as a reference with PR measured by 530, 645 (red), and 470 nm (blue) wavelength light PPG during baseline and while performing hand waving in 12 participants. In addition, we examined the change of signal-to-noise ratio (SNR) by motion for each of the three wavelengths used for the PPG. The results showed that the limit of agreement in Bland-Altman plots between the HR measured by ECG and PR measured by 530 nm light PPG (±0.61 bpm) was smaller than that achieved when using 645 and 470 nm light PPG (±3.20 bpm and ±2.23 bpm, respectively). The ΔSNR (the difference between baseline and task values) of 530 and 470nm light PPG was significantly smaller than ΔSNR for red light PPG. In conclusion, 530 nm light PPG could be a more suitable method than 645 and 470nm light PPG for monitoring HR in normal daily life.

  18. Growth and photomorphogenesis of pepper plants under red light-emitting diodes with supplemental blue or far-red lighting

    Science.gov (United States)

    Brown, C. S.; Schuerger, A. C.; Sager, J. C.

    1995-01-01

    Light-emitting diodes (LEDs) are a potential irradiation source for intensive plant culture systems and photobiological research. They have small size, low mass, a long functional life, and narrow spectral output. In this study, we measured the growth and dry matter partitioning of 'Hungarian Wax' pepper (Capsicum annuum L.) plants grown under red LEDs compared with similar plants grown under red LEDs with supplemental blue or far-red radiation or under broad spectrum metal halide (MH) lamps. Additionally, we describe the thermal and spectral characteristics of these sources. The LEDs used in this study had a narrow bandwidth at half peak height (25 nm) and a focused maximum spectral output at 660 nm for the red and 735 nm for the far-red. Near infrared radiation (800 to 3000 nm) was below detection and thermal infrared radiation (3000 to 50,000 nm) was lower in the LEDs compared to the MH source. Although the red to far-red ratio varied considerably, the calculated phytochrome photostationary state (phi) was only slightly different between the radiation sources. Plant biomass was reduced when peppers were grown under red LEDs in the absence of blue wavelengths compared to plants grown under supplemental blue fluorescent lamps or MH lamps. The addition of far-red radiation resulted in taller plants with greater stem mass than red LEDs alone. There were fewer leaves under red or red plus far-red radiation than with lamps producing blue wavelengths. These results indicate that red LEDs may be suitable, in proper combination with other wavelengths of light, for the culture of plants in tightly controlled environments such as space-based plant culture systems.

  19. Blue light induced free radicals from riboflavin in degradation of crystal violet by microbial viability evaluation.

    Science.gov (United States)

    Liang, Ji-Yuan; Yuann, Jeu-Ming P; Hsie, Zong-Jhe; Huang, Shiuh-Tsuen; Chen, Chiing-Chang

    2017-09-01

    Crystal violet (CV) is applied in daily use mainly as a commercial dye and antimicrobial agent. Waste water containing CV may affect aquatic ecosystems. Riboflavin, also known as vitamin B 2 , is non-toxic and an essential vitamin required for the functions of the human body. Riboflavin is photosensitive to UV and visible light in terms of generating reactive oxygen species. This study investigated the potential application of blue light on riboflavin, so as to come up with an effective way of degrading CV during its treatment. Photosensitivity of CV leading to degradation in the presence of riboflavin was investigated by light intensity, exposure time, and irradiation dosage. The degradation of CV during riboflavin photolysis treatment was studied by a UV/vis spectrometry and chromatography. The effects of CV degradation on microbial viability are relevant when considering the influences on the ecosystem. This study proved that riboflavin photochemical treatment with blue light degrades CV dye by ROS formation. The riboflavin photolysis-treated CV solution appeared to be transparent during conformational transformations of the CV that was rearranged by free radical species generated from riboflavin photolysis. After riboflavin photolysis, colony-forming units (CFUs) were determined for each CV solution. CFU preservation was 85.2% for the CV dissolved riboflavin solution treated with blue light irradiation at 2.0mW/cm 2 for 120min. Degradation of CV by riboflavin photochemical procedures can greatly reduce antimicrobial ability and serve as an environmental friendly waste water treatment method. Our results presented here concerning riboflavin photolysis in degradation of CV provide a novel technique, and a simple and safe practice for environmental decontamination processes. Copyright © 2017 Elsevier B.V. All rights reserved.

  20. Role of wide bandgap host in the degradation of blue phosphorescent organic light-emitting diodes

    Science.gov (United States)

    Yang, R. Y.; Li, X. M.; Cao, X. A.

    2017-08-01

    Accelerated reliability tests of blue phosphorescent organic light-emitting diodes (OLEDs) comprising bis[(4,6-difluorophenyl)pyridinato-N,C2](picolinato)-iridium(III) (FIrpic) doped in four different wide bandgap hosts were conducted. The half-life of the OLEDs stressed under a high current density of 100 mA/cm2 varied in a wide range, revealing an important role of the host. Pulsed current stressing with a 1% duty cycle was performed to suppress self-heating, but only extended the lifetime by 2-3.2×. For blue OLEDs with a host favoring hole transport, current stressing caused a shift of the recombination zone toward the anode, turning the emission color to greenish blue. These results suggest that device degradation was mainly caused by charge-trapping defects generated within a narrow zone close to the electron-transport layer. It is expected that the lifetime of blue phosphorescent OLEDs can be effectively extended by selecting an appropriate host which has good stability, enables efficient charge injection and balanced charge transport in the emissive layer.

  1. The Blue Light-Dependent Polyubiquitination and Degradation of Arabidopsis Cryptochrome2 Requires Multiple E3 Ubiquitin Ligases.

    Science.gov (United States)

    Liu, Qing; Wang, Qin; Liu, Bin; Wang, Wei; Wang, Xu; Park, Joon; Yang, Zhenming; Du, Xinglin; Bian, Mingdi; Lin, Chentao

    2016-10-01

    Cryptochromes are blue light receptors regulated by light-dependent ubiquitination and degradation in both plant and animal lineages. The Arabidopsis genome encodes two cryptochromes, CRY1 and CRY2, of which CRY2 undergoes blue light-dependent ubiquitination and 26S proteasome-dependent degradation. The molecular mechanism regulating blue light-dependent proteolysis of CRY2 is still not fully understood. We found that the F-box proteins ZEITLUPE (ZTL) and Lov Kelch Protein2 (LKP2), which mediate blue light suppression of degradation of the CRY2 signaling partner CIB1, are not required for the blue light-dependent CRY2 degradation. We further showed that the previously reported function of the COP1-SPA1 protein complex in blue light-dependent CRY2 degradation is more likely to be attributable to its cullin 4 (CUL4)-based E3 ubiquitin ligase activity than its activity as the cryptochrome signaling partner. However, the blue light-dependent CRY2 degradation is only partially impaired in the cul4 mutant, the cop1-5 null mutant and the spa1234 quadruple mutant, suggesting a possible involvement of additional E3 ubiquitin ligases in the regulation of CRY2. Consistent with this hypothesis, we demonstrated that the blue light-dependent CRY2 degradation is significantly impaired in the temperature-sensitive cul1 mutant allele (axr6-3), especially under the non-permissive temperature. Based on these and other results presented, we propose that photoexcited CRY2 undergoes Lys48-linked polyubiquitination catalyzed by the CUL4- and CUL1-based E3 ubiquitin ligases. © The Author 2016. Published by Oxford University Press on behalf of Japanese Society of Plant Physiologists. All rights reserved. For permissions, please email: journals.permissions@oup.com.

  2. Exposure to Blue Light Increases Subsequent Functional Activation of the Prefrontal Cortex During Performance of a Working Memory Task

    Science.gov (United States)

    Alkozei, Anna; Smith, Ryan; Pisner, Derek A.; Vanuk, John R.; Berryhill, Sarah M.; Fridman, Andrew; Shane, Bradley R.; Knight, Sara A.; Killgore, William D.S.

    2016-01-01

    Study Objectives: Prolonged exposure to blue wavelength light has been shown to have an alerting effect, and enhances performance on cognitive tasks. A small number of studies have also shown that relatively short exposure to blue light leads to changes in functional brain responses during the period of exposure. The extent to which blue light continues to affect brain functioning during a cognitively challenging task after cessation of longer periods of exposure (i.e., roughly 30 minutes or longer), however, has not been fully investigated. Methods: A total of 35 healthy participants (18 female) were exposed to either blue (469 nm) (n = 17) or amber (578 nm) (n = 18) wavelength light for 30 minutes in a darkened room, followed immediately by functional magnetic resonance imaging (fMRI) while undergoing a working memory task (N-back task). Results: Participants in the blue light condition were faster in their responses on the N-back task and showed increased activation in the dorsolateral (DLPFC) and ventrolateral (VLPFC) prefrontal cortex compared to those in the amber control light condition. Furthermore, greater activation within the VLPFC was correlated with faster N-back response times. Conclusions: This is the first study to suggest that a relatively brief, single exposure to blue light has a subsequent beneficial effect on working memory performance, even after cessation of exposure, and leads to temporarily persisting functional brain changes within prefrontal brain regions associated with executive functions. These findings may have broader implication for using blue-enriched light in a variety of work settings where alertness and quick decision-making are important. Citation: Alkozei A, Smith R, Pisner DA, Vanuk JR, Berryhill SM, Fridman A, Shane BR, Knight SA, Killgore WD. Exposure to blue light increases subsequent functional activation of the prefrontal cortex during performance of a working memory task. SLEEP 2016;39(9):1671–1680. PMID:27253770

  3. Damage threshold in adult rabbit eyes after scleral cross-linking by riboflavin/blue light application.

    Science.gov (United States)

    Iseli, Hans Peter; Körber, Nicole; Karl, Anett; Koch, Christian; Schuldt, Carsten; Penk, Anja; Liu, Qing; Huster, Daniel; Käs, Josef; Reichenbach, Andreas; Wiedemann, Peter; Francke, Mike

    2015-10-01

    Several scleral cross-linking (SXL) methods were suggested to increase the biomechanical stiffness of scleral tissue and therefore, to inhibit axial eye elongation in progressive myopia. In addition to scleral cross-linking and biomechanical effects caused by riboflavin and light irradiation such a treatment might induce tissue damage, dependent on the light intensity used. Therefore, we characterized the damage threshold and mechanical stiffening effect in rabbit eyes after application of riboflavin combined with various blue light intensities. Adult pigmented and albino rabbits were treated with riboflavin (0.5 %) and varying blue light (450 ± 50 nm) dosages from 18 to 780 J/cm(2) (15 to 650 mW/cm(2) for 20 min). Scleral, choroidal and retinal tissue alterations were detected by means of light microscopy, electron microscopy and immunohistochemistry. Biomechanical changes were measured by shear rheology. Blue light dosages of 480 J/cm(2) (400 mW/cm(2)) and beyond induced pathological changes in ocular tissues; the damage threshold was defined by the light intensities which induced cellular degeneration and/or massive collagen structure changes. At such high dosages, we observed alterations of the collagen structure in scleral tissue, as well as pigment aggregation, internal hemorrhages, and collapsed blood vessels. Additionally, photoreceptor degenerations associated with microglia activation and macroglia cell reactivity in the retina were detected. These pathological alterations were locally restricted to the treated areas. Pigmentation of rabbit eyes did not change the damage threshold after a treatment with riboflavin and blue light but seems to influence the vulnerability for blue light irradiations. Increased biomechanical stiffness of scleral tissue could be achieved with blue light intensities below the characterized damage threshold. We conclude that riboflavin and blue light application increased the biomechanical stiffness of scleral tissue at

  4. Optical design of a reaction chamber for weakly absorbed light. II. Parallel mirrors, multitravel

    International Nuclear Information System (INIS)

    Devaney, J.J.; Finch, F.T.

    1975-06-01

    This report outlines the possibilities to be found using one or more diffraction-limited high-quality light beams to activate a weakly absorbing gas in a regime where the diffraction spread can be controlled by converging optical devices to within a ratio of √2 of the minimum at the beam waist (corresponding lengths between converging elements are within twice the Rayleigh range). Our designs use plane or cylindrical parallel mirrors down which a light beam is repeatedly reflected. In the first design variation, the beam is re-reflected up the parallel mirrors to the entrance aperture where it can be returned repeatedly for a number of multiply reflecting ''travels'' up and down the parallel mirror reaction chamber. In the second variation, the return of the beam after each multiply reflecting ''travel'' down the chamber is external to the chamber and is achieved by two mirror reflections. For diffraction control the return mirrors can be made converging. For multiple laser excitation, any of the external return mirrors can be replaced by a laser. The advantage of these designs is a high degree of uniformity of chamber illumination with a reasonably high number of passes. Drawbacks of the designs are the large space needed for beam return (many tens of meters for some parameters) and (common to all high optical quality chambers) the figuring and reflectivity demands on the mirrors. (U.S.)

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

    Science.gov (United States)

    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.

  6. Effects of blue or violet light on the inactivation of Staphylococcus aureus by riboflavin-5'-phosphate photolysis.

    Science.gov (United States)

    Wong, Tak-Wah; Cheng, Chien-Wei; Hsieh, Zong-Jhe; Liang, Ji-Yuan

    2017-08-01

    The light sensitive compound riboflavin-5'-phosphate (or flavin mononucleotide, FMN) generates reactive oxygen species (ROS) upon photo-irradiation. FMN is required by all flavoproteins because it is a cofactor of biological blue-light receptors. The photochemical effects of FMN after irradiation by blue or violet light on the inactivation of Staphylococcus aureus strains, including a methicillin-resistant strain (MRSA), were investigated in this study. Upon blue- or violet-light photo-treatment, FMN was shown to inactivate S. aureus due to the generated ROS. Effective bacterial inactivation can be achieved by FMN photolysis without an exogenous electron provider. Inactivation rates of 94.9 and 95.2% in S. aureus and MRSA, respectively, can be reached by blue light irradiation (2.0mW/cm 2 ) with 120μM FMN for 120min. A lower FMN concentration and a shorter time are required to reach similar effects by violet light irradiation. Inactivation rates of 96.3 and 97.0% in S. aureus and MRSA, respectively, can be reached by violet light irradiation (1.0mW/cm 2 ) with 30μM FMN for 30min. The sensitivity of the inherent photosensitizers is lower under blue-light irradiation. A long exposure photolytic treatment of FMN by blue light is required to inactivate S. aureus. Violet light was found to be more efficient in S. aureus inactivation at the same radiant intensity. FMN photolysis with blue or violet light irradiation enhanced the inactivation rates of S. aureus and MRSA. FMN photochemical treatment could be a supplemental technique in hygienic decontamination processes. Copyright © 2017 Elsevier B.V. All rights reserved.

  7. Light-absorbing Particles in Snow in the context of climate, snowpack & glaciers: Where do we stand?

    Science.gov (United States)

    Doherty, S. J.

    2016-12-01

    This talk will review recent progress and challenges in quantifying the effects of light-absorbing particles in snow on climate and on snow and glacier melt. In addition to black carbon (BC), field measurements have revealed that brown carbon (BrC) from combustion, mineral dust, soil organics and, in some cases, algae can also play important roles in determining snow albedo. I will review the strengths and limitations of the techniques used to quantify each. I will also overview what we know about how light-absorbing particles in snow compare to other factors affecting snow and glacier albedo and melt, and emphasize the need for such a wholistic view.

  8. Early changes in gene expression induced by blue light irradiation of A2E-laden retinal pigment epithelial cells

    DEFF Research Database (Denmark)

    van der Burght, Barbro W; Hansen, Morten; Olsen, Jørgen

    2013-01-01

    investigated the differential gene expression in RPE cells that had accumulated the lipofuscin fluorophore A2E and were exposed to blue light (430 nm). Methods:  A2E-laden RPE cells were exposed to blue light (A2E/430 nm) at various time intervals. Cell death was quantified using Dead Red staining, and RNA...... irradiated with blue light were clearly distinguishable from the control samples. We found differential regulation of genes belonging to the following functional groups: transcription factors, stress response, apoptosis and immune response. Among the last mentioned were downregulation of four genes......). Conclusion:  This study demonstrates that blue light irradiation of A2E-laden RPE cells can alter the transcription of genes belonging to different functional pathways including stress response, apoptosis and the immune response. We suggest that these molecules may be associated to the pathogenesis of AMD...

  9. Blue-Light Inhibition of Listeria monocytogenes Growth Is Mediated by Reactive Oxygen Species and Is Influenced by σB and the Blue-Light Sensor Lmo0799.

    Science.gov (United States)

    O'Donoghue, Beth; NicAogáin, Kerrie; Bennett, Claire; Conneely, Alan; Tiensuu, Teresa; Johansson, Jörgen; O'Byrne, Conor

    2016-07-01

    Listeria monocytogenes senses blue light via the flavin mononucleotide-containing sensory protein Lmo0799, leading to activation of the general stress response sigma factor SigB (σ(B)). In this study, we investigated the physiological response of this foodborne pathogen to blue light. We show that blue light (460 to 470 nm) doses of 1.5 to 2 mW cm(-2) cause inhibition of growth on agar-based and liquid culture media. The inhibitory effects are dependent on cell density, with reduced effects evident when high cell numbers are present. The addition of 20 mM dimethylthiourea, a scavenger of reactive oxygen species, or catalase to the medium reverses the inhibitory effects of blue light, suggesting that growth inhibition is mediated by the formation of reactive oxygen species. A mutant strain lacking σ(B) (ΔsigB) was found to be less inhibited by blue light than the wild type, likely indicating the energetic cost of deploying the general stress response. When a lethal dose of light (8 mW cm(-2)) was applied to cells, the ΔsigB mutant displayed a marked increase in sensitivity to light compared to the wild type. To investigate the role of the blue-light sensor Lmo0799, mutants were constructed that either had a deletion of the gene (Δlmo0799) or alteration in a conserved cysteine residue at position 56, which is predicted to play a pivotal role in the photocycle of the protein (lmo0799 C56A). Both mutants displayed phenotypes similar to the ΔsigB mutant in the presence of blue light, providing genetic evidence that residue 56 is critical for light sensing in L. monocytogenes Taken together, these results demonstrate that L. monocytogenes is inhibited by blue light in a manner that depends on reactive oxygen species, and they demonstrate clear light-dependent phenotypes associated with σ(B) and the blue-light sensor Lmo0799. Listeria monocytogenes is a bacterial foodborne pathogen that can cause life-threatening infections in humans. It is known to be able to

  10. Blue-Light Inhibition of Listeria monocytogenes Growth Is Mediated by Reactive Oxygen Species and Is Influenced by σB and the Blue-Light Sensor Lmo0799

    Science.gov (United States)

    O'Donoghue, Beth; NicAogáin, Kerrie; Bennett, Claire; Conneely, Alan; Tiensuu, Teresa; Johansson, Jörgen

    2016-01-01

    ABSTRACT Listeria monocytogenes senses blue light via the flavin mononucleotide-containing sensory protein Lmo0799, leading to activation of the general stress response sigma factor SigB (σB). In this study, we investigated the physiological response of this foodborne pathogen to blue light. We show that blue light (460 to 470 nm) doses of 1.5 to 2 mW cm−2 cause inhibition of growth on agar-based and liquid culture media. The inhibitory effects are dependent on cell density, with reduced effects evident when high cell numbers are present. The addition of 20 mM dimethylthiourea, a scavenger of reactive oxygen species, or catalase to the medium reverses the inhibitory effects of blue light, suggesting that growth inhibition is mediated by the formation of reactive oxygen species. A mutant strain lacking σB (ΔsigB) was found to be less inhibited by blue light than the wild type, likely indicating the energetic cost of deploying the general stress response. When a lethal dose of light (8 mW cm−2) was applied to cells, the ΔsigB mutant displayed a marked increase in sensitivity to light compared to the wild type. To investigate the role of the blue-light sensor Lmo0799, mutants were constructed that either had a deletion of the gene (Δlmo0799) or alteration in a conserved cysteine residue at position 56, which is predicted to play a pivotal role in the photocycle of the protein (lmo0799 C56A). Both mutants displayed phenotypes similar to the ΔsigB mutant in the presence of blue light, providing genetic evidence that residue 56 is critical for light sensing in L. monocytogenes. Taken together, these results demonstrate that L. monocytogenes is inhibited by blue light in a manner that depends on reactive oxygen species, and they demonstrate clear light-dependent phenotypes associated with σB and the blue-light sensor Lmo0799. IMPORTANCE Listeria monocytogenes is a bacterial foodborne pathogen that can cause life-threatening infections in humans. It is known to

  11. Post-illumination pupil response after blue light: Reliability of optimized melanopsin-based phototransduction assessment.

    Science.gov (United States)

    van der Meijden, Wisse P; te Lindert, Bart H W; Bijlenga, Denise; Coppens, Joris E; Gómez-Herrero, Germán; Bruijel, Jessica; Kooij, J J Sandra; Cajochen, Christian; Bourgin, Patrice; Van Someren, Eus J W

    2015-10-01

    Melanopsin-containing retinal ganglion cells have recently been shown highly relevant to the non-image forming effects of light, through their direct projections on brain circuits that regulate alertness, mood and circadian rhythms. A quantitative assessment of functionality of the melanopsin-signaling pathway could be highly relevant in order to mechanistically understand individual differences in the effects of light on these regulatory systems. We here propose and validate a reliable quantification of the melanopsin-dependent Post-Illumination Pupil Response (PIPR) after blue light, and evaluated its sensitivity to dark adaptation, time of day, body posture, and light exposure history. Pupil diameter of the left eye was continuously measured during a series of light exposures to the right eye, of which the pupil was dilated using tropicamide 0.5%. The light exposure paradigm consisted of the following five consecutive blocks of five minutes: baseline dark; monochromatic red light (peak wavelength: 630 nm, luminance: 375 cd/m(2)) to maximize the effect of subsequent blue light; dark; monochromatic blue light (peak wavelength: 470 nm, luminance: 375 cd/m(2)); and post-blue dark. PIPR was quantified as the difference between baseline dark pupil diameter and post-blue dark pupil diameter (PIPR-mm). In addition, a relative PIPR was calculated by dividing PIPR by baseline pupil diameter (PIPR-%). In total 54 PIPR assessments were obtained in 25 healthy young adults (10 males, mean age ± SD: 26.9 ± 4.0 yr). From repeated measurements on two consecutive days in 15 of the 25 participants (6 males, mean age ± SD: 27.8 ± 4.3 yrs) test-retest reliability of both PIPR outcome parameters was calculated. In the presence of considerable between-subject differences, both outcome parameters had very high test-retest reliability: Cronbach's α > 0.90 and Intraclass Correlation Coefficient > 0.85. In 12 of the 25 participants (6 males, mean age ± SD: 26.5

  12. Photochemical Reactions of the LOV and LOV-Linker Domains of the Blue Light Sensor Protein YtvA

    NARCIS (Netherlands)

    Choi, S.; Nakasone, Y.; Hellingwerf, K.J.; Terazima, M.

    2016-01-01

    YtvA is a blue light sensor protein composed of an N-terminal LOV (light-oxygen-voltage) domain, a linker helix, and the C-terminal sulfate transporter and anti-sigma factor antagonist domain. YtvA is believed to act as a positive regulator for light and salt stress responses by regulating the

  13. Hot excited state management for long-lived blue phosphorescent organic light-emitting diodes

    Science.gov (United States)

    Lee, Jaesang; Jeong, Changyeong; Batagoda, Thilini; Coburn, Caleb; Thompson, Mark E.; Forrest, Stephen R.

    2017-05-01

    Since their introduction over 15 years ago, the operational lifetime of blue phosphorescent organic light-emitting diodes (PHOLEDs) has remained insufficient for their practical use in displays and lighting. Their short lifetime results from annihilation between high-energy excited states, producing energetically hot states (>6.0 eV) that lead to molecular dissociation. Here we introduce a strategy to avoid dissociative reactions by including a molecular hot excited state manager within the device emission layer. Hot excited states transfer to the manager and rapidly thermalize before damage is induced on the dopant or host. As a consequence, the managed blue PHOLED attains T80=334+/-5 h (time to 80% of the 1,000 cd m-2 initial luminance) with a chromaticity coordinate of (0.16, 0.31), corresponding to 3.6+/-0.1 times improvement in a lifetime compared to conventional, unmanaged devices. To our knowledge, this significant improvement results in the longest lifetime for such a blue PHOLED.

  14. Histone Deacetylase HDA-2 Regulates Trichoderma atroviride Growth, Conidiation, Blue Light Perception, and Oxidative Stress Responses.

    Science.gov (United States)

    Osorio-Concepción, Macario; Cristóbal-Mondragón, Gema Rosa; Gutiérrez-Medina, Braulio; Casas-Flores, Sergio

    2017-02-01

    Fungal blue-light photoreceptors have been proposed as integrators of light and oxidative stress. However, additional elements participating in the integrative pathway remain to be identified. In Trichoderma atroviride, the blue-light regulator (BLR) proteins BLR-1 and -2 are known to regulate gene transcription, mycelial growth, and asexual development upon illumination, and recent global transcriptional analysis revealed that the histone deacetylase-encoding gene hda-2 is induced by light. Here, by assessing responses to stimuli in wild-type and Δhda-2 backgrounds, we evaluate the role of HDA-2 in the regulation of genes responsive to light and oxidative stress. Δhda-2 strains present reduced growth, misregulation of the con-1 gene, and absence of conidia in response to light and mechanical injury. We found that the expression of hda-2 is BLR-1 dependent and HDA-2 in turn is essential for the transcription of early and late light-responsive genes that include blr-1, indicating a regulatory feedback loop. When subjected to reactive oxygen species (ROS), Δhda-2 mutants display high sensitivity whereas Δblr strains exhibit the opposite phenotype. Consistently, in the presence of ROS, ROS-related genes show high transcription levels in wild-type and Δblr strains but misregulation in Δhda-2 mutants. Finally, chromatin immunoprecipitations of histone H3 acetylated at Lys9/Lys14 on cat-3 and gst-1 promoters display low accumulation of H3K9K14ac in Δblr and Δhda-2 strains, suggesting indirect regulation of ROS-related genes by HDA-2. Our results point to a mutual dependence between HDA-2 and BLR proteins and reveal the role of these proteins in an intricate gene regulation landscape in response to blue light and ROS. Trichoderma atroviride is a free-living fungus commonly found in soil or colonizing plant roots and is widely used as an agent in biocontrol as it parasitizes other fungi, stimulates plant growth, and induces the plant defense system. To survive in

  15. Early changes in staurosporine-induced differentiated RGC-5 cells indicate cellular injury response to nonlethal blue light exposure.

    Science.gov (United States)

    Zhang, Pei; Huang, Chen; Wang, Wei; Wang, Minshu

    2015-06-01

    Blue light has been previously demonstrated to induce injury of retinal cells. The cellular responses to nonlethal blue light exposure for each type of retinal cell are of particular interest but remain undetermined. Based on the doses of blue light reported in previous research to be nonlethal to retinal pigment epithelial cells, here we investigated whether and to what extent such doses of blue light are cytotoxic to staurosporine-differentiated RGC-5 cells. RGC-5 cells were differentiated for 24 hours using 200 nM staurosporine. The resulting cells were cultured and exposed to blue light at three different energy levels (1, 10, and 50 J cm(-2)). Cellular morphologies were investigated with an inverted microscope and cell viability was assessed with a Cell Counting Kit-8 (CCK-8) assay. The generation of intracellular reactive oxygen species (ROS) was evaluated by H2DCFDA. After loading of MitoTracker Green FM dye, the mitochondrial contents were analyzed using flow cytometry. The lactate dehydrogenase (LDH) activities in the media were also measured. The level of lipid peroxidation was determined by measuring the amount of malondialdehyde (MDA). Treatment of the cells for 24 hours with 200 nM staurosporine successfully induced the differentiation of RGC-5 cells. No morphological changes were observed in the ssdRGC-5 cells exposed to blue light at 50 J cm(-2), which was the highest energy level tested. Exposure of the ssdRGC-5 cells to this energy level of blue light did, however, decrease their numbers by approximately 72.1% compared to the numbers of such cells found after being left in the dark. Remarkably, the levels of ROS generation and mitochondrial contents were, respectively, increased to 142% and 118% of those of the control by a 10 J cm(-2) exposure of blue light. The LDH activities and MDA levels exhibited no obvious changes in the blue light-exposed ssdRGC-5 cells compared to the control cells. In vitro nonlethal blue light exposure led to cellular

  16. Impairment of extramitochondrial oxidative phosphorylation in mouse rod outer segments by blue light irradiation.

    Science.gov (United States)

    Calzia, Daniela; Panfoli, Isabella; Heinig, Nora; Schumann, Ulrike; Ader, Marius; Traverso, Carlo Enrico; Funk, Richard H W; Roehlecke, Cora

    2016-06-01

    Exposure to short wavelength light causes increased reactive oxygen intermediates production in the outer retina, particularly in the rod Outer Segments (OS). Consistently, the OS were shown to conduct aerobic ATP production through the ectopic expression of the electron transfer chain complexes I-IV and F1Fo-ATP synthase. These facts prompted us to verify if the oxidative phosphorylation in the OS is implied in the oxidative damage of the blue-light (BL) treated OS, in an organotypic model of mouse retina. Whole mouse eyeball cultures were treated with short wavelength BL (peak at 405 nm, output power 1 mW/cm(2)) for 6 h. Immunogold transmission electron microscopy confirmed the expression of Complex I and F1Fo-ATP synthase in the OS. In situ histochemical assays on unfixed sections showed impairment of respiratory Complexes I and II after BL exposure, both in the OS and IS, utilized as a control. Basal O2 consumption and ATP synthesis were impaired in the OS purified from blue-light irradiated eyeball cultures. Electron transfer capacity between Complex I and II as well as activity of Complexes I and II was decreased in blue-light irradiated purified OS. The severe malfunctioning of the OS aerobic respiratory capacity after 6 h BL treatment may be the consequence of a self-induced damage. BL exposure would cause an initial over-functioning of both the phototransduction and respiratory chain, with reactive oxygen species production. In a self-renewal vicious cycle, membrane and protein oxidative damage, proton leakage and uncoupling, would impair redox chains, perpetuating the damage and causing hypo-metabolism with eventual apoptosis of the rod. Data may shed new light on the rod-driven retinopathies such as Age Related Macular Degeneration, of which blue-light irradiated retina represents a model. Copyright © 2016 Elsevier B.V. and Société Française de Biochimie et Biologie Moléculaire (SFBBM). All rights reserved.

  17. Heating of Newborn Infants due to Blue Light-Emitting Diode Fibreoptic Phototherapy Pads.

    Science.gov (United States)

    Ng, Pei Ling; Carlisle, Tony; Ly, Marleesa; Morris, Scott Adam

    2017-01-01

    Surface temperatures of fibreoptic phototherapy pads using a high intensity blue light-emitting diode (LED) light source have not been studied. The aim of this study was to measure the temperature of LED fibreoptic phototherapy pads during phototherapy in a bench-top study, and to determine temperature effects on babies during phototherapy. A commercially available LED fibreoptic phototherapy system was tested. In a bench-top setting, pad surface temperatures were measured before, during and after a 12-h period of phototherapy (10 different LED light box-pad combinations). A prospective, cohort study of well babies at >34 weeks' gestation receiving phototherapy was then conducted to determine changes in pad and body temperatures during a 90-min phototherapy period. In the bench-top study, the mean (95% CI) pad temperature was 21.8°C (21.5-22.1) before lights, 27.0°C (26.5-27.5) after 12 h of lights, and 22.1°C (21.9-22.4) 8 h after turning off the lights (F = 366.1, p phototherapy was linearly correlated with irradiance (r = 0.89, p phototherapy was 38.9°C. Axillary temperature increased by a mean (95% CI) of 0.3°C (0.1-0.5), p LED fibreoptic phototherapy pads are heated by high-intensity blue light. The thermal environment and temperature of babies should be monitored closely during LED fibreoptic phototherapy. A temperature probe placed between the skin and the pad will not accurately reflect the core temperature during fibreoptic phototherapy. © 2017 S. Karger AG, Basel.

  18. Photobiological interactions of blue light and photosynthetic photon flux: effects of monochromatic and broad-spectrum light sources.

    Science.gov (United States)

    Cope, Kevin R; Snowden, M Chase; Bugbee, Bruce

    2014-01-01

    Photosynthesis (Pn) and photomorphogenesis (Pm) are affected by light quality, light intensity and photoperiod. Although blue light (BL) is necessary for normal development, it is less efficient in driving Pn than other wavelengths of photosynthetically active radiation. The effects of BL on Pm are highly species dependent. Here we report the interacting effects of BL and photosynthetic photon flux (PPF) on growth and development of lettuce, radish and pepper. We used light-emitting diode (LED) arrays to provide BL fractions from 11% to 28% under broad-spectrum white LEDs, and from 0.3% to 92% under monochromatic LEDs. All treatments were replicated three times at each of two PPFs (200 and 500 μmol m(-2) s(-1)). Other than light quality, environmental conditions were uniformly maintained across chambers. Regardless of PPF, BL was necessary to prevent shade-avoidance responses in radish and lettuce. For lettuce and radish, increasing BL reduced stem length, and for both species, there were significant interactions of BL with PPF for leaf expansion. Increasing BL reduced petiole length in radish and flower number in pepper. BL minimally affected pepper growth and other developmental parameters. Pepper seedlings were more photobiologically sensitive than older plants. Surprisingly, there were few interactions between monochromatic and broad-spectrum light sources. © 2013 The American Society of Photobiology.

  19. Efficient blue organic light-emitting devices based on oligo(phenylenevinylene)

    Science.gov (United States)

    Zhang, Yingfang; Cheng, Gang; Chen, Shufen; Li, Yan; Zhao, Yi; Liu, Shiyong; He, Feng; Tian, Leilei; Ma, Yuguang

    2006-05-01

    Highly bright and efficient blue organic light-emitting devices based on two oligo(phenylenevinylene) derivatives, 1,4-di(4'-N,N-diphenylaminostyryl)benzene (DPA-DSB) and 2,5,2',5'-tetrastyryl-biphenyl (TSB), are fabricated. Using poly(3,4-ethylenedioxythiophene):poly(styrene sulfonic acid) combined with 4,4',4″-tri(N-carbazolyl) triphenylamine as the hole-transporting layer and DPA-DSB doped TSB as the blue emitter, a maximum luminous efficiency of 12.2 cd/A (corresponding to an external quantum efficiency of 6.2%) and a maximum power efficiency of 6.39lm/W are obtained. The maximum brightness of 17350cd/m2 is attained. These fairly high brightness and efficiencies are due to the efficient energy transfer from TSB to DPA-DSB and depression of concentration quenching by doping.

  20. Low-intensity blue-enriched white light (750 lux) and standard bright light (10 000 lux) are equally effective in treating SAD. A randomized controlled study

    NARCIS (Netherlands)

    Meesters, Ybe; Dekker, Vera; Schlangen, Luc J. M.; Bos, Elske H.; Ruiter, Martine J.

    2011-01-01

    Background: Photoreceptor cells containing melanopsin play a role in the phase-shifting effects of short-wavelength light. In a previous study, we compared the standard light treatment (SLT) of SAD with treatment using short-wavelength blue-enriched white light (BLT). Both treatments used the same

  1. Degradation of phosphorescent blue organic light-emitting diodes (OLED); Degradation der phosphoreszenten blauen organischen Leuchtdioden

    Energy Technology Data Exchange (ETDEWEB)

    Chiu, Chien-Shu

    2011-07-01

    Phosphorescent organic materials harvest singlet and triplet excitons through inter-system crossing and improve the efficiency of organic light-emitting diodes (OLEDs). This improvement increases the potential of OLEDs, particularly white phosphorescent OLEDs (PHOLEDs), for lighting application. Although much progress has been made in the development of white PHOLEDs, the lifetime of phosphorescent emitters, especially the blue emitter, still needs to be improved. This thesis discusses the developments of blue PHOLEDs and investigations of degradation mechanisms. For development of blue PHOLEDs, two phosphorescent blue emitters were investigated: commercially available FIrpic and B1 provided by BASF. By varying the matrix and blocker materials, diode efficiency and lifetime have been investigated and improved. Blue PHOLEDs with emitter B1 show better efficiency and lifetime than devices with FIrpic. From lifetime measurement with constant DC current density, intrinsic degradation including luminance loss and voltage increase on both FIrpic and B1 PHOLEDs was observed. Photoluminescence measurement shows degradation in the emitting layers. To investigate the degradation of emitter layers, single-carrier devices with emitter systems or pure matrix materials were fabricated. Degradation on these devices was investigated by applying constant DC current, UV-irradiation and combination of both. We found that due to excited states (excitons), FIrpic molecules become unstable and polarons would enhance the degradation of FIrpic during DC operation and UV-excitation. To investigate the impact the exciton formation and exciton decay have on the degradation of FIrpic molecules, red phosphorescent emitter Ir(MDQ){sub 2}(acac) was doped in blue emitter layer TCTA:20% FIrpic. The doping concentration of Ir(MDQ){sub 2}(acac) was much lower than FIrpic to ensure that most of the exciton formation occurred on FIrpic molecules. Lower triplet energy of Ir(MDQ){sub 2}(acac) molecules

  2. Daytime Effect of Monochromatic Blue Light on EEG Activity Depends on Duration and Timing of Exposure in Young Men.

    Science.gov (United States)

    Iskra-Golec, Irena; Golonka, Krystyna; Wyczesany, Miroslaw; Smith, Lawrence; Siemiginowska, Patrycja; Wątroba, Joanna

    2017-01-01

    Growing evidence suggests an alerting effect of monochromatic blue light on brain activity. Little is known about the moderation of those effects by timing and duration of exposure. The present electroencephalography (EEG ) study examined such moderations on delta, theta, alpha1, alpha2, and beta EEG bands. A counterbalanced repeated-measures design was applied. The 16-hr daytime period was divided into three sessions: 07:00-12:20, 12:20-17:40, and 17:40-23:00 (timing of exposure). Two light conditions comparable in luminance but differing in wavelength were applied, namely polychromatic white light and monochromatic blue light (460 nm). There were two durations of exposure-the shorter one lasting 30 min and the longer one lasting 4 hrs. Thirty male students participated in the study. Four factors analyses of variance (ANOV As, for light conditions, timing of exposure, duration of exposure, and brain area) were performed on each EEG band. Results indicated an alerting effect of short exposure to monochromatic blue light at midday and in the evening, which was demonstrated by a decrease in lower frequency bands (alpha1, delta, and theta, respectively). Long exposure to blue light may have a reverse effect, especially in the morning and at midday, when increases in lower frequency bands (theta in the morning and theta and alpha1 at midday) were observed. It can be concluded that the daytime effect of monochromatic blue light on EEG activity depends on timing and duration of exposure.

  3. Highly efficient greenish-blue platinum-based phosphorescent organic light-emitting diodes on a high triplet energy platform

    Energy Technology Data Exchange (ETDEWEB)

    Chang, Y. L., E-mail: yilu.chang@mail.utoronto.ca; Gong, S., E-mail: sgong@chem.utoronto.ca; White, R.; Lu, Z. H., E-mail: zhenghong.lu@utoronto.ca [Department of Materials Science and Engineering, University of Toronto, 184 College St., Toronto, Ontario M5S 3E4 (Canada); Wang, X.; Wang, S., E-mail: wangs@chem.queensu.ca [Department of Chemistry, Queen' s University, 90 Bader Lane, Kingston, Ontario K7L 3N6 (Canada); Yang, C. [Department of Chemistry, Wuhan University, Wuhan 430072 (China)

    2014-04-28

    We have demonstrated high-efficiency greenish-blue phosphorescent organic light-emitting diodes (PHOLEDs) based on a dimesitylboryl-functionalized C^N chelate Pt(II) phosphor, Pt(m-Bptrz)(t-Bu-pytrz-Me). Using a high triplet energy platform and optimized double emissive zone device architecture results in greenish-blue PHOLEDs that exhibit an external quantum efficiency of 24.0% and a power efficiency of 55.8 lm/W. This record high performance is comparable with that of the state-of-the-art Ir-based sky-blue organic light-emitting diodes.

  4. Quantifying the blue shift in the light absorption of small gold nanoparticles

    International Nuclear Information System (INIS)

    Tsekov, Roumen; Georgiev, Peter; Simeonova, Silviya; Balashev, Konstantin

    2017-01-01

    The dependence of the surface plasmons resonance (SPR) frequency on the size of gold nanoparticles (GNPs) is experimentally studied. The measured data for the SPR frequency by UV-Vis spectroscopy and GNPs diameter by Dynamic Light Scattering (DLS), Transmission Electron Microscopy (TEM) and Atomic Force Microscopy (AFM) are collected in the course of classical citrate GNPs synthesis. The relationship between the GNPs size and the blue shift of the light absorption is presented. They are fitted by an equation with a single free parameter, the dielectric permittivity of the surrounding media. Thus, the refractive index of the surrounding media is determined, which characterizes the GNPs surface shell. Key words: Gold nanoparticles (GNPs), Surface plasmon resonance (SPR), Dynamic Light Scattering (DLS), Transmission Electron Microscopy (TEM), Atomic Force Microscopy (AFM)

  5. Treatment of attention deficit hyperactivity disorder insomnia with blue wavelength light-blocking glasses

    Directory of Open Access Journals (Sweden)

    Fargason RE

    2013-01-01

    Full Text Available Rachel E Fargason, Taylor Preston, Emily Hammond, Roberta May, Karen L GambleDepartment of Psychiatry and Behavioral Neurobiology, University of Alabama at Birmingham School of Medicine, Birmingham, AL, USABackground: The aim of this study was to examine a nonmedical treatment alternative to medication in attention deficit hyperactivity disorder (ADHD insomnia, in which blue wavelength light-blocking glasses are worn during the evening hours to counteract the phase-delaying effect of light. Outcome measures included sleep quality and midsleep time. The capacity of ADHD subjects to comply with treatment using the glasses was assessed.Methods: Daily bedtime, wake-up time, and compliance diaries were used to assess sleep quality and timing during a baseline observation week and a 2-week intervention period. The Pittsburgh Sleep Quality Index (PSQI was administered following baseline and intervention. The intervention protocol consisted of use of blue wavelength-blocking glasses and a moderate lighting environment during evening hours.Results: Partial and variable compliance were noted, with only 14 of 22 subjects completing the study due to nonadherence with wearing the glasses and diary completion. Despite the minimum 3-hour recommendation, glasses were worn, on average, for 2.4 hours daily. Lighting was reduced for only 58.7% of the evening. Compared with baseline, the intervention resulted in significant improvement in global PSQI scores, PSQI subcomponent scores, and sleep diary measures of morning refreshment after sleep (P = 0.037 and night-time awakenings (P = 0.015. Global PSQI scores fell from 11.15 to 4.54, dropping below the cut-off score of 5 for clinical insomnia. The more phase-delayed subjects, ie, those with an initial midsleep time after 4:15 am, trended towards an earlier midsleep time by 43.2 minutes following the intervention (P = 0.073. Participants reported less anxiety following the intervention (P = 0.048.Conclusions

  6. ESR study of camphorquinone/amine photoinitiator systems using blue light-emitting diodes.

    Science.gov (United States)

    Teshima, Wataru; Nomura, Yuji; Tanaka, Nobuyuki; Urabe, Hidenori; Okazaki, Masayuki; Nahara, Yukinori

    2003-05-01

    New light-activation units equipped with high-illuminant blue light-emitting diodes (LEDs) have recently been proposed as a replacement for the halogen units that are widely used in dentistry to polymerize light-cured resins. The photoinitiators in light-cured dental resins, typified by the camphorquinone (CQ)/amine photoinitiator system, generate primary radicals with light irradiation that attack the double bonds of resin monomers. The physical properties of the cured resins are affected by the generation of primary radicals during the initial stage of polymerization. This study examined two types of photoinitiator systems, CQ/DMPT and CQ/DMAEMA, and three types of curing units, a new LED unit and two conventional halogen units. The primary radicals generated by irradiation were quantified using electron spin resonance (ESR) spectroscopy with a trapping method, using phenyl-tert-butyl nitrone as the trapping agent. The energy efficiencies of the LED and halogen units were compared by quantifying the generated radicals and emitted light energy (J/cm(2)). The energy required to generate a given amount of radicals using the LED unit was smaller than that using the halogen units (p<0.05). These results suggest that the new LED unit performs better than conventional halogen units with respect to light energy.

  7. Three-dimensional graphene foam-based transparent conductive electrodes in GaN-based blue light-emitting diodes

    Science.gov (United States)

    Kim, Byung-Jae; Yang, Gwangseok; Joo Park, Min; Seop Kwak, Joon; Hyeon Baik, Kwang; Kim, Donghwan; Kim, Jihyun

    2013-04-01

    We demonstrated three-dimensional (3D) graphene foam-based transparent conductive electrodes in GaN-based blue light-emitting diodes (LEDs). A 3D graphene foam structure grown on 3D Cu foam using a chemical vapor deposition method was transferred onto a p-GaN layer of blue LEDs. Optical and electrical performances were greatly enhanced by employing 3D graphene foam as transparent conductive electrodes in blue LED devices, which were analyzed by electroluminescence measurements, micro-Raman spectroscopy, and light intensity-current-voltage testing. The forward operating voltage and the light output power at an injection current of 100 mA of the GaN-based blue LEDs with a graphene foam-based transparent conductive electrode were improved by ˜26% and ˜14%, respectively. The robustness, high transmittance, and outstanding conductivity of 3D graphene foam show great potentials for advanced transparent conductive electrodes in optoelectronic devices.

  8. Non-invasive plant growth measurements for detection of blue-light dose response of stem elongation in Chrysanthemum morifolium

    DEFF Research Database (Denmark)

    Kjær, Katrine Heinsvig

    2012-01-01

    . In the present study a non-invasive plant growth sensor (PlantEye, Phenospex B.V, Heerlen, NL) was tested in analysing changes in diurnal stem elongation patterns and plant height in response to the spectral quality of the light environment. Plants were grown in four different LED supplemental lighting...... treatments with 0%, 12.5%, 18.5% and 22.5% blue light under greenhouse conditions in winter (18 h day/4 h night). The non-invasive measurements were carried out automatically every four hour with three repetitions, and supported by manual measurements of plant height every third day. A strong linear relation...... between the non-invasive measurements and manual measurements of plant height was achieved, and a blue-light dose-response showing a decrease in plant height in relation to an increase in blue light was demonstrated. However, the non-invasive plant growth sensor was not able to distinguish between diurnal...

  9. Blue light induced reactive oxygen species from flavin mononucleotide and flavin adenine dinucleotide on lethality of HeLa cells.

    Science.gov (United States)

    Yang, Ming-Yeh; Chang, Chih-Jui; Chen, Liang-Yü

    2017-08-01

    Photodynamic therapy (PDT) is a safe and non-invasive treatment for cancers and microbial infections. Various photosensitizers and light sources have been developed for clinical cancer therapies. Flavin mononucleotide (FMN) and flavin adenine dinucleotide (FAD) are the cofactor of enzymes and are used as photosensitizers in this study. Targeting hypoxia and light-triggering reactive oxygen species (ROS) are experimental strategies for poisoning tumor cells in vitro. HeLa cells are committed to apoptosis when treated with FMN or FAD and exposed to visible blue light (the maximum emitted wavelength of blue light is 462nm). Under blue light irradiation at 3.744J/cm 2 (=0.52mW/cm 2 irradiated for 2h), the minimal lethal dose is 3.125μM and the median lethal doses (LD 50 ) for FMN and FAD are 6.5μM and 7.2μM, respectively. Individual exposure to visible blue light irradiation or riboflavin photosensitizers does not produce cytotoxicity and no side effects are observed in this study. The western blotting results also show that an intrinsic apoptosis pathway is activated by the ROS during photolysis of riboflavin analogues. Blue light triggers the cytotoxicity of riboflavins on HeLa cells in vitro. Based on these results, this is a feasible and efficient of PDT with an intrinsic photosensitizer for cancer research. Copyright © 2017 Elsevier B.V. All rights reserved.

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

  11. Grey Tienshan Urumqi Glacier No.1 and light-absorbing impurities.

    Science.gov (United States)

    Ming, Jing; Xiao, Cunde; Wang, Feiteng; Li, Zhongqin; Li, Yamin

    2016-05-01

    The Tienshan Urumqi Glacier No.1 (TUG1) usually shows "grey" surfaces in summers. Besides known regional warming, what should be responsible for largely reducing its surface albedo and making it look "grey"? A field campaign was conducted on the TUG1 on a selected cloud-free day of 2013 after a snow fall at night. Fresh and aged snow samples were collected in the field, and snow densities, grain sizes, and spectral reflectances were measured. Light-absorbing impurities (LAIs) including black carbon (BC) and dust, and number concentrations and sizes of the insoluble particles (IPs) in the samples were measured in the laboratory. High temperatures in summer probably enhanced the snow ageing. During the snow ageing process, the snow density varied from 243 to 458 kg m(-3), associated with the snow grain size varying from 290 to 2500 μm. The concentrations of LAIs in aged snow were significantly higher than those in fresh snow. Dust and BC varied from 16 ppm and 25 ppb in fresh snow to 1507 ppm and 1738 ppb in aged snow, respectively. Large albedo difference between the fresh and aged snow suggests a consequent forcing of 180 W m(-2). Simulations under scenarios show that snow ageing, BC, and dust were responsible for 44, 25, and 7 % of the albedo reduction in the accumulation zone, respectively.

  12. Photomultipliers gain monitoring at the one percent level with a blue light pulser

    International Nuclear Information System (INIS)

    Berger, J.; Bermond, M.; Besson, P.; Favier, J.; Pessard, H.; Poulet, M.

    1988-07-01

    We describe a method and an experimental layout allowing the monitoring of photomultipliers gain. We use artificial blue light (Spark-gap with filter: 436 ± 20 nm) and three reference detectors. Short term and long term measurements are presented. The results indicate a precision better than 0.5% for the short term and 1.4% for the long term determinations. This gain monitoring system has been developed for a new neutrino oscillation reactor experiment (600 photomultipliers) starting at the Bugey nuclear plant

  13. Efficiency and stability of a phosphor-conversion white light source using a blue laser diode

    Directory of Open Access Journals (Sweden)

    G. Ledru

    2014-10-01

    Full Text Available A white light source using direct phosphor-conversion excited by a blue laser diode is presented. In this preliminary study we have investigated the influence of phosphor’s thickness and operating current of the laser diode over the (x, y chromaticity coordinates, Correlated Color Temperature (CCT and Color Rendering Index (CRI. The best values found were 4000 K and 94. A 40 lm/W luminous efficacy was achieved together with a CRI close to 90 for an operating current of 0.8 A. Those values, to the best of our knowledge, were not previously reported in the literature.

  14. Electron dynamics in unoccupied molecular orbitals of two blue-light-emitting organic electroluminescent materials

    Science.gov (United States)

    Karlsson, H. S.; Read, K.; Haight, R.

    2002-05-01

    The lowest unoccupied molecular orbital (LUMO) in the two blue-light-emitting organic luminescent materials bis(2-methyl-8-quinolinolato)(para-phenyl-phenolato)aluminum and 1,4-bis(2,2-diphenylvinyl)biphenyl was studied by femtosecond laser pump-and-probe photoemission and compared with tris(8-hydroxyquinoline)aluminum. We have determined the energy gap between the LUMO and the highest occupied molecular orbital and studied the LUMO decay dynamics in these materials. The differences in decay rates are shown to be related to the morphology of the evaporated films.

  15. Changes in plasma membrane aquaporin gene expression under osmotic stress and blue light in tomato

    Czech Academy of Sciences Publication Activity Database

    Balarynová, Jana; Danihlík, J.; Fellner, Martin

    2018-01-01

    Roč. 40, č. 2 (2018), č. článku 27. ISSN 0137-5881 R&D Projects: GA MŠk(CZ) LO1204 Institutional support: RVO:61389030 Keywords : male-sterile mutant * arabidopsis-thaliana * seed-germination * abscisic-acid * solanum-lycopersicon * nitric-oxide * 7b-1 * protein * hypocotyl * responses * Tomato * Seed * Aquaporins * Blue light * 7B-1 mutant * Mannitol * PIPs Subject RIV: EB - Genetics ; Molecular Biology OBOR OECD: Genetics and heredity (medical genetics to be 3) Impact factor: 1.364, year: 2016

  16. Exposure to Blue Light Increases Subsequent Functional Activation of the Prefrontal Cortex During Performance of a Working Memory Task.

    Science.gov (United States)

    Alkozei, Anna; Smith, Ryan; Pisner, Derek A; Vanuk, John R; Berryhill, Sarah M; Fridman, Andrew; Shane, Bradley R; Knight, Sara A; Killgore, William D S

    2016-09-01

    Prolonged exposure to blue wavelength light has been shown to have an alerting effect, and enhances performance on cognitive tasks. A small number of studies have also shown that relatively short exposure to blue light leads to changes in functional brain responses during the period of exposure. The extent to which blue light continues to affect brain functioning during a cognitively challenging task after cessation of longer periods of exposure (i.e., roughly 30 minutes or longer), however, has not been fully investigated. A total of 35 healthy participants (18 female) were exposed to either blue (469 nm) (n = 17) or amber (578 nm) (n = 18) wavelength light for 30 minutes in a darkened room, followed immediately by functional magnetic resonance imaging (fMRI) while undergoing a working memory task (N-back task). Participants in the blue light condition were faster in their responses on the N-back task and showed increased activation in the dorsolateral (DLPFC) and ventrolateral (VLPFC) prefrontal cortex compared to those in the amber control light condition. Furthermore, greater activation within the VLPFC was correlated with faster N-back response times. This is the first study to suggest that a relatively brief, single exposure to blue light has a subsequent beneficial effect on working memory performance, even after cessation of exposure, and leads to temporarily persisting functional brain changes within prefrontal brain regions associated with executive functions. These findings may have broader implication for using blue-enriched light in a variety of work settings where alertness and quick decision-making are important. © 2016 Associated Professional Sleep Societies, LLC.

  17. Psychophysical Measurements of Luminance Contrast Sensitivity and Color Discrimination with Transparent and Blue-Light Filter Intraocular Lenses.

    Science.gov (United States)

    da Costa, Marcelo Fernandes; Júnior, Augusto Paranhos; Lottenberg, Claudio Luiz; Castro, Leonardo Cunha; Ventura, Dora Fix

    2017-12-01

    The purpose of this study was to measure luminance contrast sensitivity and color vision thresholdfs in normal subjects using a blue light filter lens and transparent intraocular lens material. Monocular luminance grating contrast sensitivity was measured with Psycho for Windows (version 2.36; Cambridge Research Systems) at 3.0, 6.0, 12.0, 20.0, and 30.0 cycles per degree of visual angle (cpd) in 15 normal subjects (eight female), with a mean age of 21.6 years (SD = 3.8 years). Chromatic discrimination was assessed with the Cambridge colour test (CCT) along the protan, deutan, and tritan color confusion axes. Both tests were performed in a darkened room under two situations: with a transparent lens and with blue light filter lens. Subjective impressions were taken by subjects regarding their visual experience under both conditions. No difference was found between the luminance contrast sensitivity measured with transparent and blue light filter. However, 13/15 (87%) of the subjects reported more comfortable vision with the blue filter. In the color vision test, tritan thresholds were significantly higher for the blue filter compared with the transparent filter (p = 0.003). For protan and deutan thresholds no differences were found. Blue-yellow color vision is impaired with the blue light filter, and no impairment occurs with the transparent filter. No significant differences in thresholds were found in the luminance contrast sensitivity comparing the blue light and transparent filters. The impact of short wavelength light filtering on intrinsically photosensitive retinal ganglion cells is also discussed.

  18. Efficient non-doped phosphorescent orange, blue and white organic light-emitting devices.

    Science.gov (United States)

    Yin, Yongming; Yu, Jing; Cao, Hongtao; Zhang, Letian; Sun, Haizhu; Xie, Wenfa

    2014-10-24

    Efficient phosphorescent orange, blue and white organic light-emitting devices (OLEDs) with non-doped emissive layers were successfully fabricated. Conventional blue phosphorescent emitters bis [4,6-di-fluorophenyl]-pyridinato-N,C(2')] picolinate (Firpic) and Bis(2,4-difluorophenylpyridinato) (Fir6) were adopted to fabricate non-doped blue OLEDs, which exhibited maximum current efficiency of 7.6 and 4.6 cd/A for Firpic and Fir6 based devices, respectively. Non-doped orange OLED was fabricated utilizing the newly reported phosphorescent material iridium (III) (pbi)₂Ir(biq), of which manifested maximum current and power efficiency of 8.2 cd/A and 7.8 lm/W. The non-doped white OLEDs were achieved by simply combining Firpic or Fir6 with a 2-nm (pbi)₂Ir(biq). The maximum current and power efficiency of the Firpic and (pbi)₂Ir(biq) based white OLED were 14.8 cd/A and 17.9 lm/W.

  19. Investigations of riboflavin photolysis via coloured light in the nitro blue tetrazolium assay for superoxide dismutase activity.

    Science.gov (United States)

    Cheng, Chien-Wei; Chen, Liang-Yü; Chou, Chan-Wei; Liang, Ji-Yuan

    2015-07-01

    Determination of the superoxide dismutase activity is an important issue in the fields of biochemistry and the medical sciences. In the riboflavin/nitro blue tetrazolium (B2/NBT) method, the light sources used for generating superoxide anion radicals from light-excited riboflavin are normally fluorescent lamps. However, the conditions of B2/NBT experiments vary. This study investigated the effect of the light source on the light-excitation of riboflavin. The effectiveness of the photolysis was controlled by the wavelength of the light source. The spectra of fluorescent lamps are composed of multiple colour lights, and the emission spectra of fluorescent lamps made by different manufacturers may vary. Blue light was determined to be the most efficient for the photochemical reaction of riboflavin in visible region. The quality of the blue light in fluorescent lamps is critical to the photo-decomposition of riboflavin. A blue light is better than a fluorescent lamp for the photo-decomposition of riboflavin. The performance of the B2/NBT method is thereby optimized. Copyright © 2015 Elsevier B.V. All rights reserved.

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

    Directory of Open Access Journals (Sweden)

    Q. Wang

    2016-11-01

    Full Text Available 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

  1. In vitro bactericidal activity of blue light (465 nm) phototherapy on meticillin-susceptible and meticillin-resistant Staphylococcus pseudintermedius.

    Science.gov (United States)

    Schnedeker, Amy H; Cole, Lynette K; Lorch, Gwendolen; Diaz, Sandra F; Bonagura, John; Daniels, Joshua B

    2017-10-01

    Staphylococcus pseudintermedius is the most common cause of bacterial skin infections in dogs. Meticillin-resistant infections have become more common and are challenging to treat. Blue light phototherapy may be an option for treating these infections. The objective of this study was to measure the in vitro bactericidal activity of 465 nm blue light on meticillin-susceptible Staphylococcus pseudintermedius (MSSP) and meticillin-resistant Staphylococcus pseudintermedius (MRSP). We hypothesized that irradiation with blue light would kill MSSP and MRSP in a dose-dependent fashion in vitro as previously reported for meticillin-resistant Staphylococcus aureus (MRSA). In six replicate experiments, each strain [MSSP, n = 1; MRSP ST-71 (KM1381) n = 1; and MRSA (BAA-1680) n = 1] were cultivated on semisolid media, irradiated using a 465 nm blue light phototherapeutic device at the cumulative doses of 56.25, 112.5 and 225 J/cm 2 and incubated overnight at 35°C. Controls were not irradiated. Colony counts (CC) were performed manually. Descriptive statistics were performed and treatment effects assessed using the Wilcoxon-Mann-Whitney rank-sum test. Bonferroni-corrected rank-sum tests were performed for post hoc analysis when significant differences were identified. There was a significant decrease in CC with blue light irradiation at all doses for MRSA (P = 0.0006) but not for MSSP (P = 0.131) or MRSP (P = 0.589). Blue light phototherapy significantly reduced CC of MRSA, but not of MSSP or MRSP. The mechanism for the relative photosensitivity of the MRSA isolate is unknown, but is hypothesized to be due to an increased concentration of porphyrin in S. aureus relative to S. pseudintermedius, which would modulate blue light absorption. © 2017 ESVD and ACVD.

  2. Blue light differentially represses mesophyll conductance in high vs low latitude genotypes of Populus trichocarpa Torr. & Gray.

    Science.gov (United States)

    Momayyezi, Mina; Guy, Robert D

    2017-06-01

    To explore what role chloroplast positioning might have in relation to latitudinal variation in mesophyll conductance (g m ) of Populus trichocarpa Torr. & Gray (black cottonwood), we examined photosynthetic response to different blue light treatments in six representative genotypes (three northern and three southern). The proportion of blue (B) to red light was varied from 0:100, 10:90, 20:80, 40:60, and 60:40 while keeping the total photosynthetic photon flux density constant. Mesophyll conductance was estimated by monitoring chlorophyll fluorescence in combination with gas exchange. Compared to the control (10% B), g m was significantly lower with increasing blue light. Consistent with a change in chloroplast positioning, there was a simultaneous but reversible decrease in chlorophyll content index (CCI), as measured by foliar greenness, while the extracted, actual chlorophyll content (ACC) remained unchanged. Blue-light-induced decreases in g m and CCI were greater in northern genotypes than in southern genotypes, both absolutely and proportionally, consistent with their inherently higher photosynthetic rate. Treatment of leaves with cytochalasin D, an inhibitor of actin-based chloroplast motility, reduced both CCI and ACC but had no effect on the CCI/ACC ratio and fully blocked any effect of blue light on CCI. Cytochalasin D reduced g m by ∼56% under 10% B, but did not block the effect of 60% B on g m , which was reduced a further 20%. These results suggest that the effect of high blue light on g m is at least partially independent of chloroplast repositioning. High blue light reduced carbonic anhydrase activity by 20% (P<0.05), consistent with a possible reduction in protein-mediated facilitation of CO 2 diffusion. Copyright © 2017 Elsevier GmbH. All rights reserved.

  3. Arabidopsis cryptochrome 1 is a soluble protein mediating blue light-dependent regulation of plant growth and development

    International Nuclear Information System (INIS)

    Lin ChenTao; Ahmad, M.; Cashmore, A.R.

    1996-01-01

    Cryptochrome 1 (CRY1) is a flavin-type blue type receptor of Arabidopsis thaliana which mediates inhibition of hypocotyl elongation. In the work described in this report it is demonstrated that CRY1 is a soluble protein expressed in both young seedlings grown either in the dark or under light, and in different organs of adult plants. The functional role of CRY1 was further investigated using transgenic Arabidopsis plants overexpressing CRY1. It is demonstrated that overexpression of CRY1 resulted in hypersensitivity to blue, UV-A, and green light for the inhibition of hypocotyl elongation response. Transgenic plants overexpressing CRY1 also exhibited a dwarf phenotype with reduced size in almost every organ. This was in keeping with the previous observation of reciprocal alterations found in hy4 mutant plants and is consistent with a hypothesis that CRY1 mediates a light-dependent process resulting in a general inhibitory effect on plant growth. In addition, transgenic plants overexpressing CRY1 showed increased anthocyanin accumulation in response to blue, UV-A, and green light in a fluence rate-dependent manner. This increase in anthocyanin accumulation in transgenic plants was shown to be concomitant with increased blue light-induction of CHS gene expression. It is concluded that CRY1 is a photoreceptor mediating blue light-dependent regulation of gene expression in addition to its affect on plant growth. (author)

  4. Enhanced quantum efficiency in blue-emitting polymer/dielectric nanolayer nanocomposite light-emitting devices

    International Nuclear Information System (INIS)

    Park, Jong Hyeok; Lim, Yong Taik; Park, O Ok; Yu, Jae-Woong; Kim, Jai Kyeong; Kim, Young Chul

    2004-01-01

    Light-emitting devices based on environmentally stable, blue-emitting polymer/dielectric nanolayer nanocomposites were fabricated by blending poly(di-octylfluorene) (PDOF) with organo-clay. By reducing the excimer formation that leads to long wavelength tails, the photoluminescence (PL) and electroluminescence (EL) color purity of the device was enhanced. When a conjugated polymer/dielectric nanolayer nanocomposite is applied to an EL device, we expect an electronic structure similar to the well-known quantum well in small nanodomains. The ratio of PDOF/organo-clay was regulated from 2:1 to 0.5:1 (w/w). The light-emitting device of 0.5:1 (w/w) blend demonstrated the highest quantum efficiency (QE), 0.72% (ph/el), which is ∼500 times higher value compared with that of the pure PDOF layer device. However, the driving voltage of the nanocomposite devices tended to increase with increasing organo-clay content

  5. Vertical thinking in blue light emitting diodes: GaN-on-graphene technology

    Science.gov (United States)

    Bayram, C.; Kim, J.; Cheng, C.-W.; Ott, J.; Reuter, K. B.; Bedell, S. W.; Sadana, D. K.; Park, H.; Dimitrakopoulos, C.

    2014-03-01

    In this work, we show that a 2D cleave layer (such as epitaxial graphene on SiC) can be used for precise release of GaNbased light emitting diodes (LEDs) from the LED-substrate interface. We demonstrate the thinnest GaN-based blue LED and report on the initial electrical and optical characteristics. Our LED device employs vertical architecture: promising excellent current spreading, improved heat dissipation, and high light extraction with respect to the lateral one. Compared to conventional LED layer release techniques used for forming vertical LEDs (such as laser-liftoff and chemical lift-off techniques), our process distinguishes itself with being wafer-scalable (large area devices are possible) and substrate reuse opportunity.

  6. Similarity between Cytokinin and Blue Light Inhibition of Cucumber Hypocotyl Elongation 1

    Science.gov (United States)

    Cohen, Lila; Gepstein, Shimon; Horwitz, Benjamin A.

    1991-01-01

    The cytokinin benzyladenine inhibited endogenous hypocotyl elongation in intact etiolated seedlings of cucumber (Cucumis sativus L.). In hypocotyl segments, the inhibitory effect of benzyladenine on growth was clearly detectable in the presence of indoleacetic acid. Fusicoccin-induced elongation was unaffected by the presence of cytokinin. The effect of cytokinin on elongation of the segments was determined by measuring changes in fresh weight, a linear function of extension growth. The effect of benzyladenine on hypocotyl growth was at least as large in segments prepared from red-light-grown seedlings as in those from seedlings grown in total darkness. A comparison was made between the inhibitory effects of cytokinin and blue light. The use of the calcium chelator ethyleneglycol-bis(β-aminoethyl ether)-N, N′-tetraacetic acid indicated that calcium ions are required for manifestation of benzyladenine-induced inhibition. Images Figure 1 PMID:16667984

  7. Self-action of continuous laser radiation and Pearcey diffraction in a water suspension with light-absorbing particles

    DEFF Research Database (Denmark)

    Angelsky, O. V.; Bekshaev, A. Ya.; Maksimyak, P. P.

    2014-01-01

    Water suspension of light-absorbing nano-sized particles is an example of a medium in which non-linear effects are present at moderate light intensities favorable for optical treatment of organic and biological objects. We study experimentally the phenomena emerging in a thin layer of such a medium......-diffraction of the incident light, here being strongly sensitive to the medium position with respect to the focus. This technique, based on the complex spatial structure of both the incident and the diffracted fields, can be employed for the detection and measurement of weak non-linearities....

  8. Molecular basis for blue light-dependent phosphorylation of Arabidopsis cryptochrome 2

    Science.gov (United States)

    Liu, Qing; Wang, Qin; Deng, Weixian; Wang, Xu; Piao, Mingxin; Cai, Dawei; Li, Yaxing; Barshop, William D.; Yu, Xiaolan; Zhou, Tingting; Liu, Bin; Oka, Yoshito; Wohlschlegel, James; Zuo, Zecheng; Lin, Chentao

    2017-01-01

    Plant cryptochromes undergo blue light-dependent phosphorylation to regulate their activity and abundance, but the protein kinases that phosphorylate plant cryptochromes have remained unclear. Here we show that photoexcited Arabidopsis cryptochrome 2 (CRY2) is phosphorylated in vivo on as many as 24 different residues, including 7 major phosphoserines. We demonstrate that four closely related Photoregulatory Protein Kinases (previously referred to as MUT9-like kinases) interact with and phosphorylate photoexcited CRY2. Analyses of the ppk123 and ppk124 triple mutants and amiR4k artificial microRNA-expressing lines demonstrate that PPKs catalyse blue light-dependent CRY2 phosphorylation to both activate and destabilize the photoreceptor. Phenotypic analyses of these mutant lines indicate that PPKs may have additional substrates, including those involved in the phytochrome signal transduction pathway. These results reveal a mechanism underlying the co-action of cryptochromes and phytochromes to coordinate plant growth and development in response to different wavelengths of solar radiation in nature. PMID:28492234

  9. Limits to depletion of blue-green light stimulated luminescence in feldspars: Implications for quartz dating

    DEFF Research Database (Denmark)

    Jain, M.; Singhvi, A.K.

    2001-01-01

    Feldspar contaminants in quartz aliquots, either as micro-inclusions or as remnant grains (due to inadequate etching) can affect the accuracy and precision of paleodose estimates based on blue-green light stimulated luminescence (BGSL). Such contamination could also alter the shape of the BGSL st...... in a polyminerallic fine grain samples; (3) age estimates based on both quartz and feldspars from the same aliquots, and (4) dating based on feldspar micro-inclusions. (C) 2001 Elsevier Science Ltd. All rights reserved.......Feldspar contaminants in quartz aliquots, either as micro-inclusions or as remnant grains (due to inadequate etching) can affect the accuracy and precision of paleodose estimates based on blue-green light stimulated luminescence (BGSL). Such contamination could also alter the shape of the BGSL......-red stimulation at elevated temperature (220 degreesC) (ETIR) permits depletions of charges in Type (A) and Type (B) to the extent that the feldspar BGSL can be reduced by up to 97% in 5 min. These results offer prospects for (1) improved precision in paleodose estimates based on quartz; (2) BGSL dating of quartz...

  10. Blue and red LED lighting effects on plant biomass, stomatal conductance, and metabolite content in nine tomato genotypes

    NARCIS (Netherlands)

    Ouzounis, T.; Heuvelink, E.; Ji, Y.; Schouten, H.J.; Visser, R.G.F.; Marcelis, L.F.M.

    2016-01-01

    A collection of nine tomato genotypes was chosen based on their diversity, phylogeny, availability of genome information, and agronomic traits. The objective of the study was to characterize the effect of red and blue LED (light-emitting diode) lighting on physiological, morphological,

  11. Human Lens Transmission of Blue Light: A Comparison of Autofluorescence-Based and Direct Spectral Transmission Determination

    DEFF Research Database (Denmark)

    Broendsted, Adam Elias; Stormly Hansen, Michael; Lund-Andersen, Henrik

    2011-01-01

    Purpose: Direct measurement of the transmission of light through the human lens is not possible in vivo unless invasive techniques are used. In the current study, a reliable in vivo estimate of the transmission of blue light through the lens was assessed by comparing an indirect and noninvasive...... method based on autofluorescence measurements with a direct method. Methods: Total transmission of blue light was measured in human donor lenses using a direct method applicable only in vitro and compared with transmittance estimates made by an in vivo applicable autofluorescence technique. Results......: Human lens transmission of blue light decreases with age by 0.7-0.8% per year at 480 nm. The comparison of methods showed that the autofluorescence-based method correlated significantly with the direct measurements (R = 0.83, p

  12. Blue superradiance from neat semiconducting alternating copolymer films

    NARCIS (Netherlands)

    Brouwer, H.J; Krasnikov, V.V.; Hilberer, A; Hadziioannou, G

    1996-01-01

    Blue superradiant emission in thin polymer films with a low energy threshold, as reported here, offers hope for the possible development of solid-state electrically pumped polymer lasers The absorbance, emission, and fluorescence spectra of the blue-light emitting copolymer

  13. High quantum efficiency in solution processed blue phosphorescent organic light-emitting diodes based on an asymmetric benzothienopyridine host

    Energy Technology Data Exchange (ETDEWEB)

    Yook, Kyoung Soo; Lee, Jun Yeob, E-mail: leej17@dankook.ac.kr

    2014-09-15

    Highly efficient blue phosphorescent organic light-emitting diodes were developed using a benzothienopyridine based host material with an asymmetric molecular structure. 3-(3-(9H-carbazol-9-yl)phenyl)benzothieno[2,3-b]pyridine (BTP1) was used as the asymmetric host material for the solution processed blue devices. The BTP1 host showed a smooth morphology with a surface roughness of 0.30 nm and high quantum efficiency of 14.5% in blue phosphorescent organic light-emitting diodes. - Highlights: • High quantum efficiency in solution processed blue devices. • Smooth film morphology with a low surface roughness. • Benzothienopyridine based asymmetric host material for solution process.

  14. Partitioning of absorbed light energy differed between the sun-exposed side and the shaded side of apple fruits under high light conditions.

    Science.gov (United States)

    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. Copyright © 2012 Elsevier Masson SAS. All rights reserved.

  15. Exposure to blue wavelength light modulates anterior cingulate cortex activation in response to 'uncertain' versus 'certain' anticipation of positive stimuli.

    Science.gov (United States)

    Alkozei, Anna; Smith, Ryan; Killgore, William D S

    2016-03-11

    Blue wavelength light has been used as an effective treatment for some types of mood disorders and circadian rhythm related sleep problems. We hypothesized that acute exposure to blue wavelength light would directly affect the functioning of neurocircuity implicated in emotion regulation (i.e., ventromedial prefrontal cortex, amygdala, insula, and anterior cingulate cortex [ACC]) during 'certain' and 'uncertain' anticipation of negative and positive stimuli. Thirty-five healthy adults were randomized to receive a thirty-minute exposure to either blue (active) or amber (placebo) light, immediately followed by an emotional anticipation task during functional magnetic resonance imaging (fMRI). In contrast to placebo, participants in the blue light group showed significantly reduced activation within the rostral ACC during 'uncertain' anticipation (i.e., uncertainty regarding whether a positive or negative stimulus would be shown) in comparison to 'certain' anticipation of a positive stimulus. These findings may be explicable in terms of interactions between blue light exposure and the influence of specific neuromodulators on ACC-mediated decision-making mechanisms. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  16. Large plasma-membrane depolarization precedes rapid blue-light-induced growth inhibition in cucumber

    Science.gov (United States)

    Spalding, E. P.; Cosgrove, D. J.

    1989-01-01

    Blue-light (BL)-induced suppression of elongation of etiolated Cucumis sativus L. hypocotyls began after a 30-s lag time, which was halved by increasing the fluence rate from 10 to 100 micromoles m-2 s-1. Prior to the growth suppression, the plasma-membrane of the irradiated cells depolarized by as much as 100 mV, then returned within 2-3 min to near its initial value. The potential difference measured with surface electrodes changed with an identical time course but opposite polarity. The lag time for the change in surface potential showed an inverse dependence on fluence rate, similar to the lag for the growth inhibition. Green light and red light caused neither the electrical response nor the rapid inhibition of growth. The depolarization by BL did not propagate to nonirradiated regions and exhibited a refractory period of about 10 min following a BL pulse. Fluence-response relationships for the electrical and growth responses provide correlational evidence that the plasma-membrane depolarization reflects an event in the transduction chain of this light-growth response.

  17. Blue-light emitting electrochemical cells comprising pyrene-imidazole derivatives

    Science.gov (United States)

    Lee, Hyeonji; Sunesh, Chozhidakath Damodharan; Subeesh, Madayanad Suresh; Choe, Youngson

    2018-04-01

    Light-emitting electrochemical cells (LECs), the next-generation lighting sources are the potential replacements for organic light-emitting diodes (OLEDs). In recent years, organic small molecules (SMs) have established the applicability in solid-state lighting, and considered as prospective active materials for LECs with higher device performance. Here, we describe the synthesis of pyrene-imidazole based SMs, PYR1, and PYR2 that differ by one pyrene unit and their characterization by various spectroscopic methods. To investigate the thermal, photophysical, and electrochemical properties of the two synthesized compounds, we performed thermogravimetric, UV-visible, photoluminescence (PL), and voltammetric measurements. The photoluminescence (PL) emission spectra of PYR1 and PYR2 measured in the acetonitrile solution, where PYR1 and PYR2 emit in the blue spectral region with peaks aligned at 383 nm and 389 nm, respectively. The fabricated LEC devices exhibited broader electroluminescence (EL) spectra with a significant red shift of the emission maxima to 446 nm and 487 nm, with CIE coordinates of (0.17, 0.18) and (0.18, 0.25) for PYR1 and PYR2, respectively. The LECs based on PYR1 and PYR2 produced maximum brightness values of 180 and 72 cd m-2 and current densities of 55 and 27 mA cm-2, respectively.

  18. Effect of Stepwise Doping on Lifetime and Efficiency of Blue and White Phosphorescent Organic Light Emitting Diodes.

    Science.gov (United States)

    Lee, Song Eun; Lee, Ho Won; Lee, Seok Jae; Koo, Ja-ryong; Lee, Dong Hyung; Yang, Hyung Jin; Kim, Hye Jeong; Yoon, Seung Soo; Kim, Young Kwan

    2015-02-01

    We investigated a light emission mechanism of blue phosphorescent organic light emitting diodes (PHOLEDs), using a stepwise doping profile of 2, 8, and 14 wt.% within the emitting layer (EML). We fabricated several blue PHOLEDs with phosphorescent blue emitter iridium(III) bis[(4,6-difluorophenyl)-pyridinato-N,C2]picolinate doped in N,N'-dicarbazolyl-3,5-benzene as a p-type host material. A blue PHOLED with the highest doping concentration as part of the EML close to an electron transporting layer showed a maximum luminous efficiency of 20.74 cd/A, and a maximum external quantum efficiency of 10.52%. This can be explained by effective electron injection through a highly doped EML side. Additionally, a white OLED based on the doping profile was fabricated with two thin red EMLs within a blue EML maintaining a thickness of 30 nm for the entire EML. Keywords: Blue Phosphorescent Organic Light Emitting Diodes, Stepwise Doping Structure, Charge Trapping Effect.

  19. Impacts of light-absorbing impurities on snow and their quantification with bidirectional reflectance measurements

    Science.gov (United States)

    Gritsevich, Maria; Peltoniemi, Jouni; Meinander, Outi; Dagsson-Waldhauserová, Pavla; Zubko, Nataliya; Hakala, Teemu; Virkkula, Aki; Svensson, Jonas; de Leeuw, Gerrit

    2017-04-01

    rate gets faster than the diffusion rate (under condition of warm outside temperatures), as it was observed at the end of the experiment reported here, dark material starts accumulating into the surface [5]. The BC deposited on snow at warm temperatures initiates rapid melting process and may cause dramatic changes on the snow surface. References 1 Peltoniemi J.I., Hakala T., Suomalainen J., Honkavaara E., Markelin L., Gritsevich M., Eskelinen J., Jaanson P., Ikonen E. (2014): Technical notes: A detailed study for the provision of measurement uncertainty and traceability for goniospectrometers. Journal of Quantitative Spectroscopy & Radiative Transfer 146, 376-390, http://dx.doi.org/10.1016/j.jqsrt.2014.04.011 2 Zubko N., Gritsevich M., Zubko E., Hakala T., Peltoniemi J.I. (2016): Optical measurements of chemically heterogeneous particulate surfaces // Journal of Quantitative Spectroscopy and Radiative Transfer, 178, 422-431, http://dx.doi.org/10.1016/j.jqsrt.2015.12.010 3 Peltoniemi J.I., Gritsevich M., Hakala T., Dagsson-Waldhauserová P., Arnalds Ó., Anttila K., Hannula H.-R., Kivekäs N., Lihavainen H., Meinander O., Svensson J., Virkkula A., de Leeuw G. (2015): Soot on snow exper- iment: bidirectional reflectance factor measurements of contaminated snow // The Cryosphere, 9, 2323-2337, http://dx.doi.org/10.5194/tc-9-2323-2015 4 Svensson J., Virkkula A., Meinander O., Kivekäs N., Hannula H.-R., Järvinen O., Peltoniemi J.I., Gritsevich M., Heikkilä A., Kontu A., Neitola K., Brus D., Dagsson-Waldhauserova P., Anttila K., Vehkamäki M., Hienola A., de Leeuw G. & Lihavainen H. (2016): Soot-doped natural snow and its albedo — results from field experiments. Boreal Environment Research, 21, 481-503, http://www.borenv.net/BER/pdfs/preprints/Svensson1498.pdf 5 Meinander O., Kontu A., Virkkula A., Arola A., Backman L., Dagsson-Waldhauserová P., Järvinen O., Manninen T., Svensson J., de Leeuw G., and Leppäranta M. (2014): Brief communication: Light-absorbing

  20. Adults of Lasioderma serricorne and Stegobium paniceum (Anobiidae: Coleoptera) Are Attracted to Ultraviolet (UV) Over Blue Light LEDs.

    Science.gov (United States)

    Hironaka, Mantaro; Kamura, Toru; Osada, Midori; Sasaki, Rikiya; Shinoda, Kazutaka; Hariyama, Takahiko; Miyatake, Takahisa

    2017-08-01

    Two species, the cigarette beetle Lasioderma serricorne (F.) and the drugstore beetle Stegobium paniceum (L.), are particularly important stored-product pests because they damage dry food. A previous study showed that L. serricorne adults are attracted more to ultraviolet (UV) and blue light wave ranges more than others such as turquoise, green, yellow, red, and warm white. However, the previous study did not equalize the amounts of light. The study also evaluated the attractiveness by the numbers of L. serricorne individuals that were lured to LED lights in a small box in the laboratory. In some storehouses, damage by S. paniceum is more serious and establishment of an effective monitoring tool is required. Therefore, in the present study, attractions of these beetles to UV and blue light traps were compared to develop a tool to monitor the beetle pests. First, adult L. serricorne and S. paniceum beetles were provided with UV- and blue-LED panels whose light intensities were equalized in the laboratory, and the walking and flying paths of each adult were recorded and measured. As a result, adults were clearly attracted to the side of UV-LED panel by walking compared to the blue one. Second, we compared the numbers of cigarette beetles collected by sticky sheets that were set in the back of UV or blue-light LED traps in a real storehouse. The results showed that these beetles were significantly more attracted to UV than blue-light LED traps, indicating the UV-LED trap is a powerful tool to monitor these two pest species. © The Authors 2017. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  1. A multilayer physically based snowpack model simulating direct and indirect radiative impacts of light-absorbing impurities in snow

    Science.gov (United States)

    Tuzet, Francois; Dumont, Marie; Lafaysse, Matthieu; Picard, Ghislain; Arnaud, Laurent; Voisin, Didier; Lejeune, Yves; Charrois, Luc; Nabat, Pierre; Morin, Samuel

    2017-11-01

    Light-absorbing impurities (LAIs) decrease snow albedo, increasing the amount of solar energy absorbed by the snowpack. Its most intuitive and direct impact is to accelerate snowmelt. Enhanced energy absorption in snow also modifies snow metamorphism, which can indirectly drive further variations of snow albedo in the near-infrared part of the solar spectrum because of the evolution of the near-surface snow microstructure. New capabilities have been implemented in the detailed snowpack model SURFEX/ISBA-Crocus (referred to as Crocus) to account for impurities' deposition and evolution within the snowpack and their direct and indirect impacts. Once deposited, the model computes impurities' mass evolution until snow melts out, accounting for scavenging by meltwater. Taking advantage of the recent inclusion of the spectral radiative transfer model TARTES (Two-stream Analytical Radiative TransfEr in Snow model) in Crocus, the model explicitly represents the radiative impacts of light-absorbing impurities in snow. The model was evaluated at the Col de Porte experimental site (French Alps) during the 2013-2014 snow season against in situ standard snow measurements and spectral albedo measurements. In situ meteorological measurements were used to drive the snowpack model, except for aerosol deposition fluxes. Black carbon (BC) and dust deposition fluxes used to drive the model were extracted from simulations of the atmospheric model ALADIN-Climate. The model simulates snowpack evolution reasonably, providing similar performances to our reference Crocus version in terms of snow depth, snow water equivalent (SWE), near-surface specific surface area (SSA) and shortwave albedo. Since the reference empirical albedo scheme was calibrated at the Col de Porte, improvements were not expected to be significant in this study. We show that the deposition fluxes from the ALADIN-Climate model provide a reasonable estimate of the amount of light-absorbing impurities deposited on the

  2. Genetics of the Blue Light-Dependent Signal Cascade That Controls Phototaxis in the Cyanobacterium Synechocystis sp. PCC6803.

    Science.gov (United States)

    Sugimoto, Yuki; Nakamura, Hiroshi; Ren, Shukun; Hori, Koichi; Masuda, Shinji

    2017-03-01

    The Synechocystis sp. PCC6803 can move on a solid surface in response to light, a phenomenon called phototaxis. Although many of the photoreceptors involved in phototaxis have been identified, the mechanisms that regulate directional motility of Synechocystis are not well understood. Previous studies showed that a mutant lacking the blue light-using flavin (BLUF) photoreceptor PixD exhibits negative phototaxis under conditions where the wild type responds positively. PixD interacts with the pseudo-response regulator-like protein PixE in a light-dependent manner, suggesting that this intermolecular interaction is important for phototaxis regulation, although genetic evidence has been lacking. To gain further insight into phototaxis regulation by PixD-PixE signaling, we constructed the deletion mutants ΔPixE and ΔPixD-ΔPixE, and characterized their phenotypes, which matched those of the wild type (positive phototaxis). Because ΔPixD exhibited negative phototaxis, PixE must function downstream of PixD. Under intense blue light (>100 μmol m-2 s-1; 470 nm) the wild type exhibited negative phototaxis, but ΔPixD-PixE exhibited positive phototaxis toward low-intensity blue light (∼0.8 μmol m-2 s-1; 470 nm). These results suggest that an unknown light-sensing system(s), that is necessary for directional cell movement, can be activated by low-intensity blue light; on the other hand, PixD needs high-intensity blue light to be activated. We also isolated spontaneous mutants that compensated for the pixE deletion. Genome-wide sequencing of the mutants revealed that the uncharacterized gene sll2003 regulates positive and negative phototaxis in response to light intensity. © The Author 2016. Published by Oxford University Press on behalf of Japanese Society of Plant Physiologists. All rights reserved. For permissions, please email: journals.permissions@oup.com.

  3. Induction of transverse polarity by blue light: an all-or-none response.

    Science.gov (United States)

    Nick, P; Schafer, E

    1991-10-01

    Phototropic stimulation induces a spatial memory. This was inferred from experiments with maize (Zea mays L.) coleoptiles involving opposing blue-light pulses, separated by variable time intervals, and rotation on a horizontal clinostat (Nick and Schafer, 1988b, Planta 175, 380-388). In those experiments, individual seedlings either curved towards the first or towards the second pulse, or they remained straight. Bending, if it occurred, seemed to be an all-or-none response. Intermediates, i.e. plants, bending only weakly, were not observed. In the first part of the present study it was attempted to create such intermediates. For this purpose the strength of the first, inducing, and the second, opposing, pulse was varied. The result was complex: (i) Individual seedlings maintained the all-or-none expression of spatial memory. (ii) However, on the level of the whole population, the time intervals at which a given response type dominated depended on the fluence ratio. (iii) Furthermore, the final curvature was determined by the fluence ratio. These results are discussed in terms of a blue-light-induced transverse polarity. This polarity initiates from a labile precursor, which can be reoriented by an opposing stimulation (indicated by the strong bending towards the second pulse). The strong curvatures towards the first pulse over long time intervals reveal that, eventually, the blue-light-induced transverse polarity becomes stabilised and thus immune to the counterpulse. In the second part of the study, the relation between phototropic transduction and transverse polarity was characterised by a phenomenological approach involving the following points: (i) Sensory adaptation for induction of transverse polarity disappears with a time course similar to that for phototropic sensory adaptatation. (ii) The fluence response for induction of transverse polarity is a saturation curve and not bell-shaped like the curve for phototropism (iii) For strong counterpulses and long

  4. Protective effects of bilberry and lingonberry extracts against blue light-emitting diode light-induced retinal photoreceptor cell damage in vitro.

    Science.gov (United States)

    Ogawa, Kenjirou; Kuse, Yoshiki; Tsuruma, Kazuhiro; Kobayashi, Saori; Shimazawa, Masamitsu; Hara, Hideaki

    2014-04-02

    Blue light is a high-energy or short-wavelength visible light, which induces retinal diseases such as age-related macular degeneration and retinitis pigmentosa. Bilberry (Vaccinium myrtillus L.) and lingonberry (Vaccinium vitis-idaea) contain high amounts of polyphenols (anthocyanins, resveratrol, and proanthocyanidins) and thus confer health benefits. This study aimed to determine the protective effects and mechanism of action of bilberry extract (B-ext) and lingonberry extract (L-ext) and their active components against blue light-emitting diode (LED) light-induced retinal photoreceptor cell damage. Cultured murine photoreceptor (661 W) cells were exposed to blue LED light following treatment with B-ext, L-ext, or their constituents (cyanidin, delphinidin, malvidin, trans-resveratrol, and procyanidin B2). 661 W cell viability was assessed using a tetrazolium salt (WST-8) assay and Hoechst 33342 nuclear staining, and intracellular reactive oxygen species (ROS) production was determined using CM-H2DCFDA after blue LED light exposure. Activation of p38 mitogen-activated protein kinase (p38 MAPK), nuclear factor-kappa B (NF-κB), and LC3, an ubiquitin-like protein that is necessary for the formation of autophagosomes, were analyzed using Western blotting. Caspase-3/7 activation caused by blue LED light exposure in 661 W cells was determined using a caspase-3/7 assay kit. B-ext, L-ext, NAC, and their active components improved the viability of 661 W cells and inhibited the generation of intracellular ROS induced by blue LED light irradiation. Furthermore, B-ext and L-ext inhibited the activation of p38 MAPK and NF-κB induced by blue LED light exposure. Finally, B-ext, L-ext, and NAC inhibited caspase-3/7 activation and autophagy. These findings suggest that B-ext and L-ext containing high amounts of polyphenols exert protective effects against blue LED light-induced retinal photoreceptor cell damage mainly through inhibition of ROS production and activation of

  5. Protective effects of bilberry and lingonberry extracts against blue light-emitting diode light-induced retinal photoreceptor cell damage in vitro

    Science.gov (United States)

    2014-01-01

    Background Blue light is a high-energy or short-wavelength visible light, which induces retinal diseases such as age-related macular degeneration and retinitis pigmentosa. Bilberry (Vaccinium myrtillus L.) and lingonberry (Vaccinium vitis-idaea) contain high amounts of polyphenols (anthocyanins, resveratrol, and proanthocyanidins) and thus confer health benefits. This study aimed to determine the protective effects and mechanism of action of bilberry extract (B-ext) and lingonberry extract (L-ext) and their active components against blue light-emitting diode (LED) light-induced retinal photoreceptor cell damage. Methods Cultured murine photoreceptor (661 W) cells were exposed to blue LED light following treatment with B-ext, L-ext, or their constituents (cyanidin, delphinidin, malvidin, trans-resveratrol, and procyanidin B2). 661 W cell viability was assessed using a tetrazolium salt (WST-8) assay and Hoechst 33342 nuclear staining, and intracellular reactive oxygen species (ROS) production was determined using CM-H2DCFDA after blue LED light exposure. Activation of p38 mitogen-activated protein kinase (p38 MAPK), nuclear factor-kappa B (NF-κB), and LC3, an ubiquitin-like protein that is necessary for the formation of autophagosomes, were analyzed using Western blotting. Caspase-3/7 activation caused by blue LED light exposure in 661 W cells was determined using a caspase-3/7 assay kit. Results B-ext, L-ext, NAC, and their active components improved the viability of 661 W cells and inhibited the generation of intracellular ROS induced by blue LED light irradiation. Furthermore, B-ext and L-ext inhibited the activation of p38 MAPK and NF-κB induced by blue LED light exposure. Finally, B-ext, L-ext, and NAC inhibited caspase-3/7 activation and autophagy. Conclusions These findings suggest that B-ext and L-ext containing high amounts of polyphenols exert protective effects against blue LED light-induced retinal photoreceptor cell damage mainly through inhibition

  6. High color rendering index white organic light-emitting diode using levofloxacin as blue emitter

    Science.gov (United States)

    Miao, Yan-Qin; Gao, Zhi-Xiang; Zhang, Ai-Qin; Li, Yuan-Hao; Wang, Hua; Jia, Hu-Sheng; Liu, Xu-Guang; Tsuboi, Taijuf

    2015-05-01

    Levofloxacin (LOFX), which is well-known as an antibiotic medicament, was shown to be useful as a 452-nm blue emitter for white organic light-emitting diodes (OLEDs). In this paper, the fabricated white OLED contains a 452-nm blue emitting layer (thickness of 30 nm) with 1 wt% LOFX doped in CBP (4,4’-bis(carbazol-9-yl)biphenyl) host and a 584-nm orange emitting layer (thickness of 10 nm) with 0.8 wt% DCJTB (4-(dicyanomethylene)-2-tert-butyl-6-(1,1,7,7-tetramethyljulolidin-4-yl-vinyl)-4H-pyran) doped in CBP, which are separated by a 20-nm-thick buffer layer of TPBi (2,2’,2”-(benzene-1,3,5-triyl)-tri(1-phenyl-1H-benzimidazole). A high color rendering index (CRI) of 84.5 and CIE chromaticity coordinates of (0.33, 0.32), which is close to ideal white emission CIE (0.333, 0.333), are obtained at a bias voltage of 14 V. Taking into account that LOFX is less expensive and the synthesis and purification technologies of LOFX are mature, these results indicate that blue fluorescence emitting LOFX is useful for applications to white OLEDs although the maximum current efficiency and luminance are not high. The present paper is expected to become a milestone to using medical drug materials for OLEDs. Project supported by the Program for New Century Excellent Talents in University of Ministry of Education of China (Grant No. NCET-13-0927), the International Science & Technology Cooperation Program of China (Grant No. 2012DFR50460), the National Natural Science Foundation of China (Grant Nos. 21101111 and 61274056), and the Shanxi Provincial Key Innovative Research Team in Science and Technology, China (Grant No. 2012041011).

  7. Efficacy and Safety of Blue Light Flexible Cystoscopy with Hexaminolevulinate in the Surveillance of Bladder Cancer: A Phase III, Comparative, Multicenter Study.

    Science.gov (United States)

    Daneshmand, Siamak; Patel, Sanjay; Lotan, Yair; Pohar, Kamal; Trabulsi, Edouard; Woods, Michael; Downs, Tracy; Huang, William; Jones, Jeffrey; O'Donnell, Michael; Bivalacqua, Trinity; DeCastro, Joel; Steinberg, Gary; Kamat, Ashish; Resnick, Matthew; Konety, Badrinath; Schoenberg, Mark; Jones, J Stephen

    2017-12-02

    We compared blue light flexible cystoscopy with white light flexible cystoscopy for the detection of bladder cancer during surveillance. Patients at high risk for recurrence received hexaminolevulinate intravesically before white light flexible cystoscopy and randomization to blue light flexible cystoscopy. All suspicious lesions were documented. Patients with suspicious lesions were referred to the operating room for repeat white and blue light cystoscopy. All suspected lesions were biopsied or resected and specimens were examined by an independent pathology consensus panel. The primary study end point was the proportion of patients with histologically confirmed malignancy detected only with blue light flexible cystoscopy. Additional end points were the false-positive rate, carcinoma in situ detection and additional tumors detected only with blue light cystoscopy. Following surveillance 103 of the 304 patients were referred, including 63 with confirmed malignancy, of whom 26 had carcinoma in situ. In 13 of the 63 patients (20.6%, 95% CI 11.5-32.7) recurrence was seen only with blue light flexible cystoscopy (p blue light cystoscopy in 9 of the 26 (34.6%, 95% CI 17.2-55.7, p Blue light cystoscopy identified additional malignant lesions in 29 of the 63 patients (46%). The false-positive rate was 9.1% for white and blue light cystoscopy. None of the 12 adverse events during surveillance were serious. Office based blue light flexible cystoscopy significantly improves the detection of patients with recurrent bladder cancer and it is safe when used for surveillance. Blue light cystoscopy in the operating room significantly improves the detection of carcinoma in situ and detects lesions that are missed with white light cystoscopy. Copyright © 2018 American Urological Association Education and Research, Inc. Published by Elsevier Inc. All rights reserved.

  8. Blue-Light Therapy following Mild Traumatic Brain Injury: Effects on White Matter Water Diffusion in the Brain.

    Science.gov (United States)

    Bajaj, Sahil; Vanuk, John R; Smith, Ryan; Dailey, Natalie S; Killgore, William D S

    2017-01-01

    Mild traumatic brain injury (mTBI) is a common and often inconspicuous wound that is frequently associated with chronic low-grade symptoms and cognitive dysfunction. Previous evidence suggests that daily blue wavelength light therapy may be effective at reducing fatigue and improving sleep in patients recovering from mTBI. However, the effects of light therapy on recovering brain structure remain unexplored. In this study, we analyzed white matter diffusion properties, including generalized fractional anisotropy, and the quantity of water diffusion in isotropic (i.e., isotropic diffusion) and anisotropic fashion (i.e., quantitative anisotropy, QA) for fibers crossing 11 brain areas known to be significantly affected following mTBI. Specifically, we investigated how 6 weeks of daily morning blue light exposure therapy (compared to an amber-light placebo condition) impacted changes in white matter diffusion in individuals with mTBI. We observed a significant impact of the blue light treatment (relative to the placebo) on the amount of water diffusion (QA) for multiple brain areas, including the corpus callosum, anterior corona radiata, and thalamus. Moreover, many of these changes were associated with improvements in sleep latency and delayed memory. These findings suggest that blue wavelength light exposure may serve as one of the potential non-pharmacological treatments for facilitating structural and functional recovery following mTBI; they also support the use of QA as a reliable neuro-biomarker for mTBI therapies.

  9. Blue-Light Therapy following Mild Traumatic Brain Injury: Effects on White Matter Water Diffusion in the Brain

    Directory of Open Access Journals (Sweden)

    Sahil Bajaj

    2017-11-01

    Full Text Available Mild traumatic brain injury (mTBI is a common and often inconspicuous wound that is frequently associated with chronic low-grade symptoms and cognitive dysfunction. Previous evidence suggests that daily blue wavelength light therapy may be effective at reducing fatigue and improving sleep in patients recovering from mTBI. However, the effects of light therapy on recovering brain structure remain unexplored. In this study, we analyzed white matter diffusion properties, including generalized fractional anisotropy, and the quantity of water diffusion in isotropic (i.e., isotropic diffusion and anisotropic fashion (i.e., quantitative anisotropy, QA for fibers crossing 11 brain areas known to be significantly affected following mTBI. Specifically, we investigated how 6 weeks of daily morning blue light exposure therapy (compared to an amber-light placebo condition impacted changes in white matter diffusion in individuals with mTBI. We observed a significant impact of the blue light treatment (relative to the placebo on the amount of water diffusion (QA for multiple brain areas, including the corpus callosum, anterior corona radiata, and thalamus. Moreover, many of these changes were associated with improvements in sleep latency and delayed memory. These findings suggest that blue wavelength light exposure may serve as one of the potential non-pharmacological treatments for facilitating structural and functional recovery following mTBI; they also support the use of QA as a reliable neuro-biomarker for mTBI therapies.

  10. Highly Efficient Blue Phosphorescent Organic Light-Emitting Diodes Employing a Host Material with Small Bandgap.

    Science.gov (United States)

    Zhang, Lei; Zhang, Ye-Xin; Hu, Yun; Shi, Xiao-Bo; Jiang, Zuo-Quan; Wang, Zhao-Kui; Liao, Liang-Sheng

    2016-06-29

    Blue phosphorescent organic light-emitting diode (PhOLED) with a high maximum external quantum efficiency (EQE) of 26.6% was achieved using a new material, 2,8-bis(9,9-dimethylacridin-10(9H)-yl)dibenzo[b,d]furan (DBF-DMS) with a small bandgap, as the host. The device with DBF-DMS showed improved performance compared with that with 1,3-di-9-carbazolylbenzene, which is ascribed to the enhancement in carrier injection and transporting abilities and material stability of DBF-DMS. A lifetime of more than 100 h (time to 50% of the initial luminance, 1000 cd/m(2) with an EQE of 19.6%) in the other DBF-DMS-based device is obtained by further utilizing better device structure. This is a report indicating that host material with a small bandgap like DBF-DMS can be successfully utilized toward blue PhOLEDs with high performance.

  11. A first-principles study of light non-metallic atom substituted blue phosphorene

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Minglei [School of Mechanical Engineering, Southeast University, Nanjing 211189, Jiangsu (China); Tang, Wencheng, E-mail: 101000185@seu.edu.cn [School of Mechanical Engineering, Southeast University, Nanjing 211189, Jiangsu (China); Ren, Qingqiang [State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083, Hunan (China); Wang, Sa-ke [Department of Physics, Southeast University, Nanjing 210096, Jiangsu (China); Yu, Jin [School of Materials Science and Engineering, Southeast University, Nanjing 211189, Jiangsu (China); Jiangsu Key Laboratory of Advanced Metallic Materials, Southeast University, Nanjing 211189, Jiangsu (China); Du, Yanhui [School of Mechanical Engineering, Southeast University, Nanjing 211189, Jiangsu (China)

    2015-11-30

    Graphical abstract: - Highlights: • All the impurities are covalently bonded to blue phosphorene (with a single vacancy). • All the substituted systems are semiconductors. • B-substituted system exhibits direct bandgap semiconductor behavior. • The band gaps with spin polarization are found in C and O-substituted systems. • Our works can paves a new route at nanoscale for novel functionalities of optical and spintronics devices. - Abstract: First-principles calculations are implemented to study the geometric, electronic and magnetic properties of light non-metallic atom (B, C, N, O and F) substituted blue phosphorene. All the substituted systems are highly stable. The B-substituted system is a direct bandgap semiconductor with a bandgap size about 1.5 eV. The C, O-substituted systems are promising systems to explore two-dimensional diluted magnetic semiconductors. Magnetism is observed for C and O substitution, while for the other impurities no magnetic moment is detected. Our works paves a new route at nanoscale for novel functionalities of optical and spintronics devices.

  12. Improved efficiency in blue phosphorescent organic light-emitting diodes by the stepwise doping structure

    Science.gov (United States)

    Yang, Liping; Wang, Xiaoping; Kou, Zhiqi; Ji, Changyan

    2017-04-01

    The electro-optical properties of the blue phosphorescent organic light-emitting diodes (PHOLEDs) can be affected by the stepwise doping structure in the emitting layer (EML). A series of multi-EML devices with different doping concentration of blue dopant (FIrpic) are fabricated. The effect of the stepwise doping structure close to the electron transport layer is more obvious than that close to the hole transport layer. When the doping concentration increases gradually from the hole injection side to the electron injection side, the maximum values of the luminance, current and power efficiency can reach to 9745 cd/m2 (at 9 V), 32.0 cd/A and 25.1 lm/W in the device with the asymmetric tri-EML structure, which is improved by about 10% compared with that in the bi-EML device. When the number of the EML is four, the performance of the device becomes worse because of the interface effect resulting from different concentration of dopant.

  13. Blocking blue light during mania - markedly increased regularity of sleep and rapid improvement of symptoms: a case report.

    Science.gov (United States)

    Henriksen, Tone E G; Skrede, Silje; Fasmer, Ole Bernt; Hamre, Børge; Grønli, Janne; Lund, Anders

    2014-12-01

    Available pharmacological treatment of mania is insufficient. Virtual darkness therapy (blue light-blocking treatment by means of orange-tinted glasses) is a promising new treatment option for mania. The basis for this might be the recently identified blue light-sensitive retinal photoreceptor, which is solely responsible for light stimulus to the circadian master clock. This is the first case report describing the clinical course of a closely monitored, hospitalized patient in a manic episode first receiving clear-lensed, and then blue light-blocking glasses. A 58-year-old Caucasian man, with bipolar I disorder and three previous manic episodes, was hospitalized during a manic episode. In addition to pharmacological treatment, he was treated with clear-lensed glasses for seven days, then one day without glasses, followed by six days of blue light-blocking glasses. During the entire observational period, he wore an actigraph with internal light sensors. Manic symptoms were unaltered during the first seven days. The transition to the blue-blocking regime was followed by a rapid and sustained decline in manic symptoms accompanied by a reduction in total sleep, a reduction in motor activity during sleep intervals, and markedly increased regularity of sleep intervals. The patient's total length of hospital stay was 20 days shorter than the average time during his previous manic episodes. The unusually rapid decline in symptoms, accompanied by uniform sleep parameter changes toward markedly increased regularity, suggest that blue-blockers might be targeting a central mechanism in the pathophysiology of mania that needs to be explored both in clinical research and in basic science. © 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  14. Light-absorbing impurities accelerate glacier melt in the Central Tibetan Plateau.

    Science.gov (United States)

    Li, Xiaofei; Kang, Shichang; He, Xiaobo; Qu, Bin; Tripathee, Lekhendra; Jing, Zhefan; Paudyal, Rukumesh; Li, Yang; Zhang, Yulan; Yan, Fangping; Li, Gang; Li, Chaoliu

    2017-06-01

    Light-absorbing impurities (LAIs), such as organic carbon (OC), black carbon (BC), and mineral dust (MD) deposited on the glacier surface can reduce albedo, thus accelerating the glacier melt. Surface fresh snow, aged snow, granular ice, and snowpits samples were collected between August 2014 and October 2015 on the Xiao Dongkemadi (XDKMD) glacier (33°04'N, 92°04'E) in the central Tibetan Plateau (TP). The spatiotemporal variations of LAIs concentrations in the surface snow/ice were observed to be consistent, differing mainly in magnitudes. LAIs concentrations were found to be in the order: granular ice>snowpit>aged snow>fresh snow, which must be because of post-depositional effects and enrichment. In addition, more intense melting led to higher LAIs concentrations exposed to the surface at a lower elevation, suggesting a strong negative relationship between LAIs concentrations and elevation. The scavenging efficiencies of OC and BC were same (0.07±0.02 for OC, 0.07±0.01 for BC), and the highest enrichments was observed in late September and August for surface snow and granular ice, respectively. Meanwhile, as revealed by the changes in the OC/BC ratios, intense glacier melt mainly occurred between August and October. Based on the SNow ICe Aerosol Radiative (SNICAR) model simulations, BC and MD in the surface snow/ice were responsible for about 52%±19% and 25%±14% of the albedo reduction, while the radiative forcing (RF) were estimated to be 42.74±40.96Wm -2 and 21.23±22.08Wm -2 , respectively. Meanwhile, the highest RF was observed in the granular ice, suggesting that the exposed glaciers melt and retreat more easily than the snow distributed glaciers. Furthermore, our results suggest that BC was the main forcing factor compared with MD in accelerating glacier melt during the melt season in the Central TP. Copyright © 2017 Elsevier B.V. All rights reserved.

  15. Blue light-dependent changes in loosely bound calcium in Arabidopsis mesophyll cells: an X-ray microanalysis study.

    Science.gov (United States)

    Łabuz, Justyna; Samardakiewicz, Sławomir; Hermanowicz, Paweł; Wyroba, Elżbieta; Pilarska, Maria; Gabryś, Halina

    2016-06-01

    Calcium is involved in the signal transduction pathway from phototropins, the blue light photoreceptor kinases which mediate chloroplast movements. The chloroplast accumulation response in low light is controlled by both phot1 and phot2, while only phot2 is involved in avoidance movement induced by strong light. Phototropins elevate cytosolic Ca(2+) after activation by blue light. In higher plants, both types of chloroplast responses depend on Ca(2+), and internal calcium stores seem to be crucial for these processes. Yet, the calcium signatures generated after the perception of blue light by phototropins are not well understood. To characterize the localization of calcium in Arabidopsis mesophyll cells, loosely bound (exchangeable) Ca(2+) was precipitated with potassium pyroantimonate and analyzed by transmission electron microscopy followed by energy-dispersive X-ray microanalysis. In dark-adapted wild-type Arabidopsis leaves, calcium precipitates were observed at the cell wall, where they formed spherical structures. After strong blue light irradiation, calcium at the apoplast prevailed, and bigger, multilayer precipitates were found. Spherical calcium precipitates were also detected at the tonoplast. After red light treatment as a control, the precipitates at the cell wall were smaller and less numerous. In the phot2 and phot1phot2 mutants, calcium patterns were different from those of wild-type plants. In both mutants, no elevation of calcium after blue light treatment was observed at the cell periphery (including the cell wall and a fragment of cytoplasm). This result confirms the involvement of phototropin2 in the regulation of Ca(2+) homeostasis in mesophyll cells. © The Author 2016. Published by Oxford University Press on behalf of the Society for Experimental Biology.

  16. Blue light-dependent changes in loosely bound calcium in Arabidopsis mesophyll cells: an X-ray microanalysis study

    Science.gov (United States)

    Łabuz, Justyna; Samardakiewicz, Sławomir; Hermanowicz, Paweł; Wyroba, Elżbieta; Pilarska, Maria; Gabryś, Halina

    2016-01-01

    Calcium is involved in the signal transduction pathway from phototropins, the blue light photoreceptor kinases which mediate chloroplast movements. The chloroplast accumulation response in low light is controlled by both phot1 and phot2, while only phot2 is involved in avoidance movement induced by strong light. Phototropins elevate cytosolic Ca2+ after activation by blue light. In higher plants, both types of chloroplast responses depend on Ca2+, and internal calcium stores seem to be crucial for these processes. Yet, the calcium signatures generated after the perception of blue light by phototropins are not well understood. To characterize the localization of calcium in Arabidopsis mesophyll cells, loosely bound (exchangeable) Ca2+ was precipitated with potassium pyroantimonate and analyzed by transmission electron microscopy followed by energy-dispersive X-ray microanalysis. In dark-adapted wild-type Arabidopsis leaves, calcium precipitates were observed at the cell wall, where they formed spherical structures. After strong blue light irradiation, calcium at the apoplast prevailed, and bigger, multilayer precipitates were found. Spherical calcium precipitates were also detected at the tonoplast. After red light treatment as a control, the precipitates at the cell wall were smaller and less numerous. In the phot2 and phot1phot2 mutants, calcium patterns were different from those of wild-type plants. In both mutants, no elevation of calcium after blue light treatment was observed at the cell periphery (including the cell wall and a fragment of cytoplasm). This result confirms the involvement of phototropin2 in the regulation of Ca2+ homeostasis in mesophyll cells. PMID:26957564

  17. Design and fabrication of adjustable red-green-blue LED light arrays for plant research

    Directory of Open Access Journals (Sweden)

    Kenitz J Dustin

    2005-08-01

    Full Text Available Abstract Background Although specific light attributes, such as color and fluence rate, influence plant growth and development, researchers generally cannot control the fine spectral conditions of artificial plant-growth environments. Plant growth chambers are typically outfitted with fluorescent and/or incandescent fixtures that provide a general spectrum that is accommodating to the human eye and not necessarily supportive to plant development. Many studies over the last several decades, primarily in Arabidopsis thaliana, have clearly shown that variation in light quantity, quality and photoperiod can be manipulated to affect growth and control developmental transitions. Light emitting diodes (LEDs has been used for decades to test plant responses to narrow-bandwidth light. LEDs are particularly well suited for plant growth chambers, as they have an extraordinary life (about 100,000 hours, require little maintenance, and use negligible energy. These factors render LED-based light strategies particularly appropriate for space-biology as well as terrestrial applications. However, there is a need for a versatile and inexpensive LED array platform where individual wavebands can be specifically tuned to produce a series of light combinations consisting of various quantities and qualities of individual wavelengths. Two plans are presented in this report. Results In this technical report we describe the practical construction of tunable red-green-blue LED arrays to support research in plant growth and development. Two light fixture designs and corresponding circuitry are presented. The first is well suited for a laboratory environment for use in a finite area with small plants, such as Arabidopsis. The second is expandable and appropriate for growth chambers. The application of these arrays to early plant developmental studies has been validated with assays of hypocotyl growth inhibition/promotion and phototropic curvature in Arabidopsis seedlings

  18. Design and fabrication of adjustable red-green-blue LED light arrays for plant research.

    Science.gov (United States)

    Folta, Kevin M; Koss, Lawrence L; McMorrow, Ryan; Kim, Hyeon-Hye; Kenitz, J Dustin; Wheeler, Raymond; Sager, John C

    2005-08-23

    Although specific light attributes, such as color and fluence rate, influence plant growth and development, researchers generally cannot control the fine spectral conditions of artificial plant-growth environments. Plant growth chambers are typically outfitted with fluorescent and/or incandescent fixtures that provide a general spectrum that is accommodating to the human eye and not necessarily supportive to plant development. Many studies over the last several decades, primarily in Arabidopsis thaliana, have clearly shown that variation in light quantity, quality and photoperiod can be manipulated to affect growth and control developmental transitions. Light emitting diodes (LEDs) has been used for decades to test plant responses to narrow-bandwidth light. LEDs are particularly well suited for plant growth chambers, as they have an extraordinary life (about 100,000 hours), require little maintenance, and use negligible energy. These factors render LED-based light strategies particularly appropriate for space-biology as well as terrestrial applications. However, there is a need for a versatile and inexpensive LED array platform where individual wavebands can be specifically tuned to produce a series of light combinations consisting of various quantities and qualities of individual wavelengths. Two plans are presented in this report. In this technical report we describe the practical construction of tunable red-green-blue LED arrays to support research in plant growth and development. Two light fixture designs and corresponding circuitry are presented. The first is well suited for a laboratory environment for use in a finite area with small plants, such as Arabidopsis. The second is expandable and appropriate for growth chambers. The application of these arrays to early plant developmental studies has been validated with assays of hypocotyl growth inhibition/promotion and phototropic curvature in Arabidopsis seedlings. The presentation of these proven plans for LED

  19. Photomorphogenesis, photosynthesis, and seed yield of wheat plants grown under red light-emitting diodes (LEDs) with and without supplemental blue lighting

    Science.gov (United States)

    Goins, G. D.; Yorio, N. C.; Sanwo, M. M.; Brown, C. S.; Sager, J. C. (Principal Investigator)

    1997-01-01

    Red light-emitting diodes (LEDs) are a potential light source for growing plants in spaceflight systems because of their safety, small mass and volume, wavelength specificity, and longevity. Despite these attractive features, red LEDs must satisfy requirements for plant photosynthesis and photomorphogenesis for successful growth and seed yield. To determine the influence of gallium aluminium arsenide (GaAlAs) red LEDs on wheat photomorphogenesis, photosynthesis, and seed yield, wheat (Triticum aestivum L., cv. 'USU-Super Dwarf') plants were grown under red LEDs and compared to plants grown under daylight fluorescent (white) lamps and red LEDs supplemented with either 1% or 10% blue light from blue fluorescent (BF) lamps. Compared to white light-grown plants, wheat grown under red LEDs alone demonstrated less main culm development during vegetative growth through preanthesis, while showing a longer flag leaf at 40 DAP and greater main culm length at final harvest (70 DAP). As supplemental BF light was increased with red LEDs, shoot dry matter and net leaf photosynthesis rate increased. At final harvest, wheat grown under red LEDs alone displayed fewer subtillers and a lower seed yield compared to plants grown under white light. Wheat grown under red LEDs+10% BF light had comparable shoot dry matter accumulation and seed yield relative to wheat grown under white light. These results indicate that wheat can complete its life cycle under red LEDs alone, but larger plants and greater amounts of seed are produced in the presence of red LEDs supplemented with a quantity of blue light.

  20. Phototransferred thermoluminescence from alpha-Al sub 2 O sub 3 :C using blue light emitting diodes

    CERN Document Server

    Bulur, E

    1999-01-01

    Phototransferred thermoluminescence (PTTL) from alpha-Al sub 2 O sub 3 :C single crystals was studied using a blue light emitting diode (LED) for phototransfer of charges from deep traps to the main dosimetry trap. The dose response was found to be linear in the region from approx 5 mGy to approx 5 Gy. It was observed that the corresponding deep traps were located near 500 deg. C and heating to temperatures >600 deg. C removes the PTTL effect induced by the light from the blue LED. The thermal activation energy of the source traps involved in the PTTL production was calculated as 3.23 eV.

  1. Evidence for the Role of Blue Light in the Development of Uveal Melanoma

    Directory of Open Access Journals (Sweden)

    Patrick Logan

    2015-01-01

    Full Text Available Uveal melanoma is the most common malignancy of the adult eye. Although it is a relatively infrequent tumor, clinical prognosis is often poor owing to a high incidence of aggressive metastatic disease, for which there are limited treatment options. Little is known about the etiology of this condition, although several risk factors have been identified. Unlike cutaneous melanoma, however, ultraviolet radiation does not figure prominently among these risk factors. In this review, we focus on an associated form of visible electromagnetic radiation, high-energy short-wave (blue light, a causative agent in various forms of age-related retina damage, as a previously overlooked risk factor in uveal melanoma development and progression. Finally, we discuss the impact of these data on contemporary ocular therapy, particularly the debate surrounding the filtering capabilities of intraocular lenses used to replace dysfunctional crystalline lenses during cataract surgery.

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

    Science.gov (United States)

    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.

  3. Evidence for Tautomerisation of Glutamine in BLUF Blue Light Receptors by Vibrational Spectroscopy and Computational Chemistry

    Science.gov (United States)

    Domratcheva, Tatiana; Hartmann, Elisabeth; Schlichting, Ilme; Kottke, Tilman

    2016-01-01

    BLUF (blue light sensor using flavin) domains regulate the activity of various enzymatic effector domains in bacteria and euglenids. BLUF features a unique photoactivation through restructuring of the hydrogen-bonding network as opposed to a redox reaction or an isomerization of the chromophore. A conserved glutamine residue close to the flavin chromophore plays a central role in the light response, but the underlying modification is still unclear. We labelled this glutamine with 15N in two representative BLUF domains and performed time-resolved infrared double difference spectroscopy. The assignment of the signals was conducted by extensive quantum chemical calculations on large models with 187 atoms reproducing the UV-vis and infrared signatures of BLUF photoactivation. In the dark state, the comparatively low frequency of 1,667 cm−1 is assigned to the glutamine C=O accepting a hydrogen bond from tyrosine. In the light state, the signature of a tautomerised glutamine was extracted with the C=N stretch at ~1,691 cm−1 exhibiting the characteristic strong downshift by 15N labelling. Moreover, an indirect isotope effect on the flavin C4=O stretch was found. We conclude that photoactivation of the BLUF receptor does not only involve a rearrangement of hydrogen bonds but includes a change in covalent bonds of the protein. PMID:26947391

  4. Comparative Study of Lettuce and Radish Grown Under Red and Blue Light-Emitting Diodes (LEDs) and White Fluorescent Lamps

    Science.gov (United States)

    Mickens, Matthew A.

    2012-01-01

    Growing vegetable crops in space will be an essential part of sustaining astronauts during long-term missions. To drive photosynthesis, red and blue light-emitting diodes (LEDs) have attracted attention because of their efficiency, longevity, small size, and safety. In efforts to optimize crop production, there have also been recent interests in analyzing the subtle effects of green light on plant growth, and to determine if it serves as a source of growth enhancement or suppression. A comparative study was performed on two short cycle crops of lettuce (Outredgeous) and radish (Cherry Bomb) grown under two light treatments. The first treatment being red and blue LEDs, and the second treatment consisting of white fluorescent lamps which contain a portion of green light. In addition to comparing biomass production, physiological characterizations were conducted on how the light treatments influence morphology, water use, chlorophyll content, and the production of A TP within plant tissues.

  5. Antimicrobial Blue Light Therapy for Infectious Keratitis: Ex Vivo and In Vivo Studies.

    Science.gov (United States)

    Zhu, Hong; Kochevar, Irene E; Behlau, Irmgard; Zhao, Jie; Wang, Fenghua; Wang, Yucheng; Sun, Xiaodong; Hamblin, Michael R; Dai, Tianhong

    2017-01-01

    To investigate the effectiveness of antimicrobial blue light (aBL) as an alternative or adjunctive therapeutic for infectious keratitis. We developed an ex vivo rabbit model and an in vivo mouse model of infectious keratitis. A bioluminescent strain of Pseudomonas aeruginosa was used as the causative pathogen, allowing noninvasive monitoring of the extent of infection in real time via bioluminescence imaging. Quantitation of bacterial luminescence was correlated to colony-forming units (CFU). Using the ex vivo and in vivo models, the effectiveness of aBL (415 nm) for the treatment of keratitis was evaluated as a function of radiant exposure when aBL was delivered at 6 or 24 hours after bacterial inoculation. The aBL exposures calculated to reach the retina were compared to the American National Standards Institute standards to estimate aBL retinal safety. Pseudomonas aeruginosa keratitis fully developed in both the ex vivo and in vivo models at 24 hours post inoculation. Bacterial luminescence in the infected corneas correlated linearly to CFU (R2 = 0.921). Bacterial burden in the infected corneas was rapidly and significantly reduced (>2-log10) both ex vivo and in vivo after a single exposure of aBL. Recurrence of infection was observed in the aBL-treated mice at 24 hours after aBL exposure. The aBL toxicity to the retina is largely dependent on the aBL transmission of the cornea. Antimicrobial blue light is a potential alternative or adjunctive therapeutic for infectious keratitis. Further studies of corneal and retinal safety using large animal models, in which the ocular anatomies are similar to that of humans, are warranted.

  6. Anatomical features of pepper plants (Capsicum annuum L.) grown under red light-emitting diodes supplemented with blue or far-red light

    Science.gov (United States)

    Schuerger, A. C.; Brown, C. S.; Stryjewski, E. C.

    1997-01-01

    Pepper plants (Capsicum annuum L. cv., Hungarian Wax) were grown under metal halide (MH) lamps or light-emitting diode (LED) arrays with different spectra to determine the effects of light quality on plant anatomy of leaves and stems. One LED (660) array supplied 90% red light at 660 nm (25nm band-width at half-peak height) and 1% far-red light between 700-800nm. A second LED (660/735) array supplied 83% red light at 660nm and 17% far-red light at 735nm (25nm band-width at half-peak height). A third LED (660/blue) array supplied 98% red light at 660nm, 1% blue light between 350-550nm, and 1% far-red light between 700-800nm. Control plants were grown under broad spectrum metal halide lamps. Plants were gron at a mean photon flux (300-800nm) of 330 micromol m-2 s-1 under a 12 h day-night photoperiod. Significant anatomical changes in stem and leaf morphologies were observed in plants grown under the LED arrays compared to plants grown under the broad-spectrum MH lamp. Cross-sectional areas of pepper stems, thickness of secondary xylem, numbers of intraxylary phloem bundles in the periphery of stem pith tissues, leaf thickness, numbers of choloplasts per palisade mesophyll cell, and thickness of palisade and spongy mesophyll tissues were greatest in peppers grown under MH lamps, intermediate in plants grown under the 660/blue LED array, and lowest in peppers grown under the 660 or 660/735 LED arrays. Most anatomical features of pepper stems and leaves were similar among plants grown under 660 or 660/735 LED arrays. The effects of spectral quality on anatomical changes in stem and leaf tissues of peppers generally correlate to the amount of blue light present in the primary light source.

  7. Dynamic Blue Light-Inducible T7 RNA Polymerases (Opto-T7RNAPs) for Precise Spatiotemporal Gene Expression Control.

    Science.gov (United States)

    Baumschlager, Armin; Aoki, Stephanie K; Khammash, Mustafa

    2017-11-17

    Light has emerged as a control input for biological systems due to its precise spatiotemporal resolution. The limited toolset for light control in bacteria motivated us to develop a light-inducible transcription system that is independent from cellular regulation through the use of an orthogonal RNA polymerase. Here, we present our engineered blue light-responsive T7 RNA polymerases (Opto-T7RNAPs) that show properties such as low leakiness of gene expression in the dark state, high expression strength when induced with blue light, and an inducible range of more than 300-fold. Following optimization of the system to reduce expression variability, we created a variant that returns to the inactive dark state within minutes once the blue light is turned off. This allows for precise dynamic control of gene expression, which is a key aspect for most applications using optogenetic regulation. The regulators, which only require blue light from ordinary light-emitting diodes for induction, were developed and tested in the bacterium Escherichia coli, which is a crucial cell factory for biotechnology due to its fast and inexpensive cultivation and well understood physiology and genetics. Opto-T7RNAP, with minor alterations, should be extendable to other bacterial species as well as eukaryotes such as mammalian cells and yeast in which the T7 RNA polymerase and the light-inducible Vivid regulator have been shown to be functional. We anticipate that our approach will expand the applicability of using light as an inducer for gene expression independent from cellular regulation and allow for a more reliable dynamic control of synthetic and natural gene networks.

  8. From Plant Infectivity to Growth Patterns: The Role of Blue-Light Sensing in the Prokaryotic World

    Directory of Open Access Journals (Sweden)

    Aba Losi

    2014-01-01

    Full Text Available Flavin-based photoreceptor proteins of the LOV (Light, Oxygen, and Voltage and BLUF (Blue Light sensing Using Flavins superfamilies are ubiquitous among the three life domains and are essential blue-light sensing systems, not only in plants and algae, but also in prokaryotes. Here we review their biological roles in the prokaryotic world and their evolution pathways. An unexpected large number of bacterial species possess flavin-based photosensors, amongst which are important human and plant pathogens. Still, few cases are reported where the activity of blue-light sensors could be correlated to infectivity and/or has been shown to be involved in the activation of specific genes, resulting in selective growth patterns. Metagenomics and bio-informatic analysis have only recently been initiated, but signatures are beginning to emerge that allow definition of a bona fide LOV or BLUF domain, aiming at better selection criteria for novel blue-light sensors. We also present here, for the first time, the phylogenetic tree for archaeal LOV domains that have reached a statistically significant number but have not at all been investigated thus far.

  9. Circadian and Sex Differences After Acute High-Altitude Exposure: Are Early Acclimation Responses Improved by Blue Light?

    Science.gov (United States)

    Silva-Urra, Juan A; Núñez-Espinosa, Cristian A; Niño-Mendez, Oscar A; Gaitán-Peñas, Héctor; Altavilla, Cesare; Toro-Salinas, Andrés; Torrella, Joan R; Pagès, Teresa; Javierre, Casimiro F; Behn, Claus; Viscor, Ginés

    2015-12-01

    The possible effects of blue light during acute hypoxia and the circadian rhythm on several physiological and cognitive parameters were studied. Fifty-seven volunteers were randomly assigned to 2 groups: nocturnal (2200-0230 hours) or diurnal (0900-1330 hours) and exposed to acute hypoxia (4000 m simulated altitude) in a hypobaric chamber. The participants were illuminated by blue LEDs or common artificial light on 2 different days. During each session, arterial oxygen saturation (Spo2), blood pressure, heart rate variability, and cognitive parameters were measured at sea level, after reaching the simulated altitude of 4000 m, and after 3 hours at this altitude. The circadian rhythm caused significant differences in blood pressure and heart rate variability. A 4% to 9% decrease in waking nocturnal Spo2 under acute hypoxia was observed. Acute hypoxia also induced a significant reduction (4%-8%) in systolic pressure, slightly more marked (up to 13%) under blue lighting. Women had significantly increased systolic (4%) and diastolic (12%) pressures under acute hypoxia at night compared with daytime pressure; this was not observed in men. Some tendencies toward better cognitive performance (d2 attention test) were seen under blue illumination, although when considered together with physiological parameters and reaction time, there was no conclusive favorable effect of blue light on cognitive fatigue suppression after 3 hours of acute hypobaric hypoxia. It remains to be seen whether longer exposure to blue light under hypobaric hypoxic conditions would induce favorable effects against fatigue. Copyright © 2015 Wilderness Medical Society. Published by Elsevier Inc. All rights reserved.

  10. Diphenylmethyl linked high-triplet-energy material as a host for deep-blue phosphorescent organic light-emitting diodes

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Chil Won [Department of Polymer Science and Engineering, Dankook University, Jukjeon-dong, Suji-gu, Yongin-si, Gyeonggi-do, 448-701 (Korea, Republic of); Gong, Myoung-Seon [Department of Nanobiomedical Science and WCU Research Center, Dankook University Graduate School, Chungnam 330-714 (Korea, Republic of); Lee, Jun Yeob, E-mail: leej17@dankook.ac.kr [Department of Polymer Science and Engineering, Dankook University, Jukjeon-dong, Suji-gu, Yongin-si, Gyeonggi-do, 448-701 (Korea, Republic of)

    2013-03-01

    A diphenylmethyl-linkage-based high-triplet-energy organic material, 3-(dibenzofuran-2-yldiphenylmethyl)-9-phenyl-9H-carbazole (TCDFCz), was synthesized as a host material for deep-blue phosphorescent organic light-emitting diodes (PHOLEDs). High-triplet-energy moieties, 9-phenylcarbazole and dibenzofuran, were connected through diphenylmethyl linkage, and high triplet energy of 2.97 eV was obtained. TCDFCz was effective as the high-triplet-energy host material for deep-blue PHOLEDs, and a high quantum efficiency of 13.1% was achieved. - Highlights: ► High quantum efficiency of 13.1% in deep blue phosphorescent device ► Phenylcarbazole and dibenzofuran as high triplet energy moieties ► High triplet energy of 2.97 eV for energy transfer to deep blue dopant.

  11. Highly efficient white phosphorescent organic light emitting diodes using a mixed host structure in deep blue emitting layer

    Energy Technology Data Exchange (ETDEWEB)

    Seo, Chang Woo; Lee, Jun Yeob, E-mail: leej17@dankook.ac.kr

    2012-05-31

    Highly efficient phosphorescent white organic light-emitting diodes (PHWOLEDs) were developed using a deep blue phosphorescent emitter doped into a mixed host of high triplet energy host materials. The deep blue emitting layer was combined with a red:green emitting layer to fabricate PHWOLEDs. A high quantum efficiency of 19.5% with a color coordinate of (0.29,0.38) and 19.8% with a color coordinate of (0.39,0.46) were achieved in the PHWOLEDs using the mixed host emitting layer doped with a deep blue phosphorescent dopant. In addition, a low optimum doping concentration below 5% in red, green and blue dopants was realized in the PHWOLEDs. - Highlights: Black-Right-Pointing-Pointer High quantum efficiency in phosphorescent white device. Black-Right-Pointing-Pointer Mixed host structure for high power efficiency. Black-Right-Pointing-Pointer Low doping concentration below 5% in phosphorescent white device.

  12. Ligand Enhanced Upconversion of Near-Infrared Photons with Nanocrystal Light Absorbers

    Science.gov (United States)

    2016-03-04

    based photon upconversion in the NIR with the use of earth -abundant materials.Introduction Multi-excitonic processes can be harnessed to reorganize...transmitter ligands per NC ( hollow blue triangles) for (a) PbS, and (b) PbSe NC versus [CPT] in the ligand exchange solution. Both of the samples

  13. SU-F-J-56: The Connection Between Cherenkov Light Emission and Radiation Absorbed Dose in Proton Irradiated Phantoms

    Energy Technology Data Exchange (ETDEWEB)

    Darafsheh, A; Kassaee, A; Finlay, J [University of Pennsylvania, Philadelphia, PA (United States); Taleei, R [UT Southwestern Medical Center, Dallas, TX (United States)

    2016-06-15

    Purpose: Range verification in proton therapy is of great importance. Cherenkov light follows the photon and electron energy deposition in water phantom. The purpose of this study is to investigate the connection between Cherenkov light generation and radiation absorbed dose in a water phantom irradiated with proton beams. Methods: Monte Carlo simulation was performed by employing FLUKA Monte Carlo code to stochastically simulate radiation transport, ionizing radiation dose deposition, and Cherenkov radiation in water phantoms. The simulations were performed for proton beams with energies in the range 50–600 MeV to cover a wide range of proton energies. Results: The mechanism of Cherenkov light production depends on the initial energy of protons. For proton energy with 50–400 MeV energy that is below the threshold (∼483 MeV in water) for Cherenkov light production directly from incident protons, Cherenkov light is produced mainly from the secondary electrons liberated as a result of columbic interactions with the incident protons. For proton beams with energy above 500 MeV, in the initial depth that incident protons have higher energy than the Cherenkov light production threshold, the light has higher intensity. As the slowing down process results in lower energy protons in larger depths in the water phantom, there is a knee point in the Cherenkov light curve vs. depth due to switching the Cherenkov light production mechanism from primary protons to secondary electrons. At the end of the depth dose curve the Cherenkov light intensity does not follow the dose peak because of the lack of high energy protons to produce Cherenkov light either directly or through secondary electrons. Conclusion: In contrast to photon and electron beams, Cherenkov light generation induced by proton beams does not follow the proton energy deposition specially close to the end of the proton range near the Bragg peak.

  14. Chronic artificial blue-enriched white light is an effective countermeasure to delayed circadian phase and neurobehavioral decrements.

    Directory of Open Access Journals (Sweden)

    Raymond P Najjar

    Full Text Available Studies in Polar Base stations, where personnel have no access to sunlight during winter, have reported circadian misalignment, free-running of the sleep-wake rhythm, and sleep problems. Here we tested light as a countermeasure to circadian misalignment in personnel of the Concordia Polar Base station during the polar winter. We hypothesized that entrainment of the circadian pacemaker to a 24-h light-dark schedule would not occur in all crew members (n = 10 exposed to 100-300 lux of standard fluorescent white (SW light during the daytime, and that chronic non-time restricted daytime exposure to melanopsin-optimized blue-enriched white (BE light would establish an a stable circadian phase, in participants, together with increased cognitive performance and mood levels. The lighting schedule consisted of an alternation between SW lighting (2 weeks, followed by a BE lighting (2 weeks for a total of 9 weeks. Rest-activity cycles assessed by actigraphy showed a stable rest-activity pattern under both SW and BE light. No difference was found between light conditions on the intra-daily stability, variability and amplitude of activity, as assessed by non-parametric circadian analysis. As hypothesized, a significant delay of about 30 minutes in the onset of melatonin secretion occurred with SW, but not with BE light. BE light significantly enhanced well being and alertness compared to SW light. We propose that the superior efficacy of blue-enriched white light versus standard white light involves melanopsin-based mechanisms in the activation of the non-visual functions studied, and that their responses do not dampen with time (over 9-weeks. This work could lead to practical applications of light exposure in working environment where background light intensity is chronically low to moderate (polar base stations, power plants, space missions, etc., and may help design lighting strategies to maintain health, productivity, and personnel safety.

  15. [Study on monosaccharide composition of intracellular polysacchride and contents of cordycepin and cordyceps polysacchride produced by Cordyceps militaris induced by blue light].

    Science.gov (United States)

    Wang, Ju-Feng; Yang, Dao-De; Li, Hu-Ming; Han, Wen-Jun

    2014-08-01

    To study effects of blue light irradiation on monosaccharide composition of intracellular polysacchride and contents of cordycepin and cordyceps polysacchride of mycelium and sporocarp in Cordyceps militaris. The monosaccharide composition of intracellular polysacchride of mycelium and sporocarp in Cordyceps militaris as materials were determined by gas chromatography after 144 h blue light irradiation. The contents of cordycepin and cordyceps polysacchride of mycelium and sporocarp in Cordyceps militaris were detected at different blue light irradiation periods. At the same time, the growth of mycelium and sporocarp in Cordyceps militaris were observed during blue light irradiation. Mycelium polysaccharide in Cordyceps militaris was a kind of heteropolysaccharide containing four kinds of monosaccharide and fruiting body polysaccharide was a kind of heteropolysaccharide containing five kinds of monosaccharide. Whether blue light irradiation or dark culture, the content changes of cordyceps polysacchride in two groups showed similar patterns in the test of mycelium polysaccharides. The content changes of cordyceps polysacchride in two groups were basically the same in the detection of sporocarp polysacchride. Cordycepin content in the two set of experiments of blue light irradiation all showed a clear upward trend in the detection of mycelium and sporocarp in Cordyceps militaris. The blue light irradiation has certain effect on the species and quantity of monosaccharide in intracellular polysaccharide. The content increase of cordycepin and cordyceps polysacchride in Cordyceps militaris are promoted by blue light irradiation. Blue light can help the morphogenesis and promote the differentiation and growth of sporocarp in Cordyceps militaris. This study is the first report about the effect of blue light on the type and quantity of the monosaccharide composition in polysaccharide of Cordyceps militaris, which will lay the foundation for further study on the metabolism

  16. Thermally Activated Delayed Fluorescence Emitters for Deep Blue Organic Light Emitting Diodes: A Review of Recent Advances

    Directory of Open Access Journals (Sweden)

    Thanh-Tuân Bui

    2018-03-01

    Full Text Available Organic light-emitting diodes offer attractive perspectives for the next generation display and lighting technologies. The potential is huge and the list of potential applications is almost endless. So far, blue emitters still suffer from noticeably inferior electroluminescence performances in terms of efficiency, lifespan, color quality, and charge injection/transport when compared to that of the other colors. Emitting materials matching the NTSC standard blue of coordinates (0.14, 0.08 are extremely rare and still constitutes the focus of numerous academic and industrial researches. In this context, we review herein the recent developments on highly emissive deep-blue thermally activated delayed fluorescence emitters that constitute the third-generation electroluminescent materials.

  17. An indole derivative as a high triplet energy hole transport material for blue phosphorescent organic light-emitting diodes

    Energy Technology Data Exchange (ETDEWEB)

    Park, Min Su; Lee, Jun Yeob, E-mail: leej17@dankook.ac.kr

    2013-12-02

    A thermally stable high triplet energy material derived from an indoloacridine core and indole hole transport units, 8,8-bis(4-(1H-indol-1-yl)phenyl)-8H-indolo[3,2,1-de]acridine (BIPIA), was synthesized as the hole transport material for deep blue phosphorescent organic light-emitting diodes. The BIPIA hole transport material showed a high triplet energy of 2.95 eV and high glass transition temperature of 142 °C. A high quantum efficiency of 19.3% was obtained in the deep blue device using BIPIA as the high triplet energy hole transport material. - Highlights: • A high triplet energy hole transport material derived from an indole • High quantum efficiency of 19.3% in deep blue phosphorescent organic light-emitting diodes • Good thermal stability with a high glass transition temperature of 142 °C.

  18. Bright light in elderly subjects with nonseasonal major depressive disorder: a double blind randomised clinical trial using early morning bright blue light comparing dim red light treatment

    Directory of Open Access Journals (Sweden)

    van Someren Eus JW

    2008-07-01

    Full Text Available Abstract Background Depression frequently occurs in the elderly. Its cause is largely unknown, but several studies point to disturbances of biological rhythmicity. In both normal aging, and depression, the functioning of the suprachiasmatic nucleus (SCN is impaired, as evidenced by an increased prevalence of day-night rhythm perturbations, such as sleeping disorders. Moreover, the inhibitory SCN neurons on the hypothalamus-pituitary adrenocortical axis (HPA-axis have decreased activity and HPA-activity is enhanced, when compared to non-depressed elderly. Using bright light therapy (BLT the SCN can be stimulated. In addition, the beneficial effects of BLT on seasonal depression are well accepted. BLT is a potentially safe, nonexpensive and well accepted treatment option. But the current literature on BLT for depression is inconclusive. Methods/Design This study aims to show whether BLT can reduce non-seasonal major depression in elderly patients. Randomized double blind placebo controlled trial in 126 subjects of 60 years and older with a diagnosis of major depressive disorder (MDD, DSM-IV/SCID-I. Subjects are recruited through referrals of psychiatric outpatient clinics and from case finding from databases of general practitioners and old-people homes in the Amsterdam region. After inclusion subjects are randomly allocated to the active (bright blue light vs. placebo (dim red light condition using two Philips Bright Light Energy boxes type HF 3304 per subject, from which the light bulbs have been covered with bright blue- or dim red light- permitting filters. Patients will be stratified by use of antidepressants. Prior to treatment a one-week period without light treatment will be used. At three time points several endocrinological, psychophysiological, psychometrically, neuropsychological measures are performed: just before the start of light therapy, after completion of three weeks therapy period, and three weeks thereafter. Discussion If BLT

  19. Arabidopsis cryptochrome 1 interacts with SPA1 to suppress COP1 activity in response to blue light

    Science.gov (United States)

    Liu, Bin; Zuo, Zecheng; Liu, Hongtao; Liu, Xuanming; Lin, Chentao

    2011-01-01

    Plant photoreceptors mediate light suppression of the E3 ubiquitin ligase COP1 (CONSTITUTIVE PHOTOMORPHOGENIC 1) to affect gene expression and photomorphogenesis. However, how photoreceptors mediate light regulation of COP1 activity remains unknown. We report here that Arabidopsis blue-light receptor cryptochrome 1 (CRY1) undergoes blue-light-dependent interaction with the COP1-interacting protein SPA1 (SUPPRESSOR OF PHYTOCHROME A). We further show that the CRY1–SPA1 interaction suppresses the SPA1–COP1 interaction and COP1-dependent degradation of the transcription factor HY5. These results are consistent with a hypothesis that photoexcited CRY1 interacts with SPA1 to modulate COP1 activity and plant development. PMID:21511871

  20. Chemical magnetoreception: bird cryptochrome 1a is excited by blue light and forms long-lived radical-pairs.

    Directory of Open Access Journals (Sweden)

    Miriam Liedvogel

    Full Text Available Cryptochromes (Cry have been suggested to form the basis of light-dependent magnetic compass orientation in birds. However, to function as magnetic compass sensors, the cryptochromes of migratory birds must possess a number of key biophysical characteristics. Most importantly, absorption of blue light must produce radical pairs with lifetimes longer than about a microsecond. Cryptochrome 1a (gwCry1a and the photolyase-homology-region of Cry1 (gwCry1-PHR from the migratory garden warbler were recombinantly expressed and purified from a baculovirus/Sf9 cell expression system. Transient absorption measurements show that these flavoproteins are indeed excited by light in the blue spectral range leading to the formation of radicals with millisecond lifetimes. These biophysical characteristics suggest that gwCry1a is ideally suited as a primary light-mediated, radical-pair-based magnetic compass receptor.

  1. Synthesis of oxocarbon-encapsulated gold nanoparticles with blue-shifted localized surface plasmon resonance by pulsed laser ablation in water with CO2 absorbers

    Science.gov (United States)

    Del Rosso, T.; Rey, N. A.; Rosado, T.; Landi, S.; Larrude, D. G.; Romani, E. C.; Freire Junior, F. L.; Quinteiro, S. M.; Cremona, M.; Aucelio, R. Q.; Margheri, G.; Pandoli, O.

    2016-06-01

    Colloidal suspensions of oxocarbon-encapsulated gold nanoparticles have been synthesized in a one-step procedure by pulsed-laser ablation (PLA) at 532 nm of a solid gold target placed in aqueous solution containing CO2 absorbers, but without any stabilizing agent. Multi-wavelength surface enhanced Raman spectroscopy allows the identification of adsorbed amorphous carbon and graphite, Au-carbonyl, Au coordinated CO2-derived bicarbonates/carbonates and hydroxyl groups around the AuNPs core. Scanning electron microscopy, energy dispersive x-ray analysis and high resolution transmission electron microscopy highlight the organic shell structure around the crystalline metal core. The stability of the colloidal solution of nanocomposites (NCs) seems to be driven by solvation forces and is achieved only in neutral or basic pH using monovalent hydroxide counter-ions (NaOH, KOH). The NCs are characterized by a blue shift of the localized surface plasmon resonance (LSPR) band typical of metal-ligand stabilization by terminal π-back bonding, attributed to a core charging effect caused by Au-carbonyls. Total organic carbon measurements detect the final content of organic carbon in the colloidal solution of NCs that is about six times higher than the value of the water solution used to perform PLA. The colloidal dispersions of NCs are stable for months and are applied as analytical probes in amino glycoside antibiotic LSPR based sensing.

  2. Ultraviolet Laser SQUID Microscope for GaN Blue Light Emitting Diode Testing

    International Nuclear Information System (INIS)

    Daibo, M; Kamiwano, D; Kurosawa, T; Yoshizawa, M; Tayama, N

    2006-01-01

    We carried out non-contacting measurements of photocurrent distributions in GaN blue light emitting diode (LED) chips using our newly developed ultraviolet (UV) laser SQUID microscope. The UV light generates the photocurrent, and then the photocurrent induces small magnetic fields around the chip. An off-axis arranged HTS-SQUID magnetometer is employed to detect a vector magnetic field whose typical amplitude is several hundred femto-tesla. Generally, it is difficult to obtain Ohmic contacts for p-type GaN because of the low hole concentration in the p-type epitaxial layer and the lack of any available metal with a higher work function compared with the p-type GaN. Therefore, a traditional probecontacted electrical test is difficult to conduct for wide band gap semiconductors without an adequately annealed electrode. Using the UV-laser SQUID microscope, the photocurrent can be measured without any electrical contact. We show the photocurrent vector map which was reconstructed from measured magnetic fields data. We also demonstrate how we found the position of a defect of the electrical short circuits in the LED chip

  3. AZO/Ag/AZO anode for resonant cavity red, blue, and yellow organic light emitting diodes

    Energy Technology Data Exchange (ETDEWEB)

    Gentle, A. R., E-mail: angus.gentle@uts.edu.au; Smith, G. B. [School of Mathematical and Physical Sciences and Institute of Nanoscale Technology, University of Technology Sydney, P.O. Box 123, Broadway, New South Wales 2007 (Australia); Yambem, S. D.; Burn, P. L.; Meredith, P. [Centre for Organic Photonics and Electronics, School of Chemistry and Molecular Biosciences and School of Mathematics and Physics, The University of Queensland, St Lucia, Queensland 4072 (Australia)

    2016-06-28

    Indium tin oxide (ITO) is the transparent electrode of choice for organic light-emitting diodes (OLEDs). Replacing ITO for cost and performance reasons is a major drive across optoelectronics. In this work, we show that changing the transparent electrode on red, blue, and yellow OLEDs from ITO to a multilayer buffered aluminium zinc oxide/silver/aluminium zinc oxide (AZO/Ag/AZO) substantially enhances total output intensity, with better control of colour, its constancy, and intensity over the full exit hemisphere. The thin Ag containing layer induces a resonant cavity optical response of the complete device. This is tuned to the emission spectra of the emissive material while minimizing internally trapped light. A complete set of spectral intensity data is presented across the full exit hemisphere for each electrode type and each OLED colour. Emission zone modelling of output spectra at a wide range of exit angles to the normal was in excellent agreement with the experimental data and hence could, in principle, be used to check and adjust production settings. These multilayer transparent electrodes show significant potential for both eliminating indium from OLEDs and spectrally shaping the emission.

  4. Highly efficient phosphorescent blue and white organic light-emitting devices with simplified architectures

    Energy Technology Data Exchange (ETDEWEB)

    Chang, Chih-Hao, E-mail: chc@saturn.yzu.edu.tw [Department of Photonics Engineering, Yuan Ze University, Chung-Li, Taiwan 32003 (China); Ding, Yong-Shung; Hsieh, Po-Wei; Chang, Chien-Ping; Lin, Wei-Chieh [Department of Photonics Engineering, Yuan Ze University, Chung-Li, Taiwan 32003 (China); Chang, Hsin-Hua, E-mail: hhua3@mail.vnu.edu.tw [Department of Electro-Optical Engineering, Vanung University, Chung-Li, Taiwan 32061 (China)

    2011-09-01

    Blue phosphorescent organic light-emitting devices (PhOLEDs) with quantum efficiency close to the theoretical maximum were achieved by utilizing a double-layer architecture. Two wide-triplet-gap materials, 1,3-bis(9-carbazolyl)benzene and 1,3,5-tri[(3-pyridyl)-phen-3-yl]benzene, were employed in the emitting and electron-transport layers respectively. The opposite carrier-transport characteristics of these two materials were leveraged to define the exciton formation zone and thus increase the probability of recombination. The efficiency at practical luminance (100 cd/m{sup 2}) was as high as 20.8%, 47.7 cd/A and 31.2 lm/W, respectively. Furthermore, based on the design concept of this simplified architecture, efficient warmish-white PhOLEDs were developed. Such two-component white organic light-emitting devices exhibited rather stable colors over a wide brightness range and yielded electroluminescence efficiencies of 15.3%, 33.3 cd/A, and 22.7 lm/W in the forward directions.

  5. Evaluation of 405nm CW visible blue light as a means of inactivating Tulane Virus on Blueberries

    Science.gov (United States)

    Introduction: Visible blue light (405nm) is effective against bacteria but its potential as a nonthermal intervention for viruses on foods, such as berries that are prone to norovirus contamination has not been evaluated. Tulane virus (TV) is now a common human norovirus surrogate that can be propa...

  6. Blue Light Emitting Diodes based on a partially conjugated Si-containing PPV-copolymer in a multilayer configuration

    NARCIS (Netherlands)

    Garten, F; Hilberer, A; Cacialli, F.; Esselink, F.J; van Dam, Y.; Schlatmann, A.R.; Friend, R.H.; Klapwijk, T.M; Hadziioannou, G

    1997-01-01

    Efficient blue Light Emitting Diodes (LEDs) based on a novel partially conjugated co-polymer (SiPPV) have been realized by a combination of techniques known to enhance the quantum efficiency of organic devices. The copolymer is homogeneously blended in a PVK-matrix to reduce the number of

  7. Cloning and analysis of the Glwc-1 and Glwc-2 genes encoding putative blue light photoreceptor from Ganoderma lucidum.

    Science.gov (United States)

    Xu, Xinran; Chen, Xiangdong; Yu, Wumengxiao; Liu, Yu; Zhang, Weiwei; Lan, Jin

    2017-08-01

    Blue light plays an important role during the growth of Ganoderma lucidum, one of the best-known medicinal macrofungi in China. In the present study, we cloned Glwc-1 and Glwc-2, the homologue of the blue light photoreceptors Ncwc-1 and Ncwc-2 of Neurospora crassa, from G. lucidum. The deduced amino acid sequence of Glwc-1 contained the similar function domains as NcWC-1 including LOV, PAS B, PAS C, and PAC domains. The deduced amino acid sequence of Glwc-2 contained PAS domain and GATA-type zinc finger (Znf) domain as well as NcWC-2. Phylogenetic analysis based on fungal WC-1 and WC-2 supported GlWC-1 and GlWC-2 were blue light receptors. The expression of Glwc-1 and Glwc-2 indicated that they might play an important role during the primordium differentiation process of G. lucidum, and the external blue light stimulation increased the expression of Glwc-1 and Glwc-2. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. The Impact of Blue Light Cystoscopy with Hexaminolevulinate (HAL) on Progression of Bladder Cancer - A New Analysis

    NARCIS (Netherlands)

    Kamat, A.M.; Cookson, M.; Witjes, J.A.; Stenzl, A.; Grossman, H.B.

    2016-01-01

    Background: The International Bladder Cancer Group (IBCG) recently proposed a new definition of disease progression in non-muscle invasive bladder cancer (NMIBC), including change in T-stage, change to T2 or higher or change from low to high grade. Objective: To establish whether blue light

  9. Manipulation of the blue light photoreceptor cryptochrome 2 in tomato affects vegetative development, flowering time, and fruit antioxidant content

    OpenAIRE

    Giliberto, Leonardo; Perrotta, Gaetano; Pallara, Patrizia; Weller, James L; Fraser, Paul D; Bramley, Peter M; Fiore, Alessia; Tavazza, Mario; Giuliano, Giovanni

    2004-01-01

    Cryptochromes are blue light photoreceptors found in plants, bacteria, and animals. In Arabidopsis, cryptochrome 2 (cry2) is involved primarily in the control of flowering time and in photomorphogenesis under low-fluence light. No data on the function of cry2 are available in plants, apart from Arabidopsis (Arabidopsis thaliana). Expression of the tomato (Solanum lycopersicum) CRY2 gene was altered through a combination of transgenic overexpression and virus-induced gene silencing. Tomato CRY...

  10. Effect of light on the content of photosynthetically active pigments in plants. Pt. 4. Chromatic adaption in blue-green algae Anabaena cylindrica and A. variabilis

    Energy Technology Data Exchange (ETDEWEB)

    Czeczuga, B.

    1986-07-15

    The photosynthetic pigments (chlorophyll a, carotenoids and phycobiliprotein pigments) of two species of the genus Anabaena grown in white, red, yellow, green and blue light were examined. The highest concentration of the cells was observed in the sample with red light in case of the both species, and the smallest with blue light. The biggest amounts of chlorophyll a and carotenoids were included in the cells of samples with the yellow and the smallest in case of the red light. The ratio of two phycobiliproteins is as follows: - in Anabaena cylindrica: the highest amount of C-phycocyanin in the cells was observed in the case of the red light, and C-phycoerytherin was found in the blue light; - in Anabaena variabiles: the highest amount of C-phycocyanien in the cells was found in case of the yellow light, and allophycocyanin was found in the blue light.

  11. Circadian phase, dynamics of subjective sleepiness and sensitivity to blue light in young adults complaining of a delayed sleep schedule.

    Science.gov (United States)

    Moderie, Christophe; Van der Maren, Solenne; Dumont, Marie

    2017-06-01

    To assess factors that might contribute to a delayed sleep schedule in young adults with sub-clinical features of delayed sleep phase disorder. Two groups of 14 young adults (eight women) were compared: one group complaining of a delayed sleep schedule and a control group with an earlier bedtime and no complaint. For one week, each subject maintained a target bedtime reflecting their habitual sleep schedule. Subjects were then admitted to the laboratory for the assessment of circadian phase (dim light melatonin onset), subjective sleepiness, and non-visual light sensitivity. All measures were timed relative to each participant's target bedtime. Non-visual light sensitivity was evaluated using subjective sleepiness and salivary melatonin during 1.5-h exposure to blue light, starting one hour after target bedtime. Compared to control subjects, delayed subjects had a later circadian phase and a slower increase of subjective sleepiness in the late evening. There was no group difference in non-visual sensitivity to blue light, but we found a positive correlation between melatonin suppression and circadian phase within the delayed group. Our results suggest that a late circadian phase, a slow build-up of sleep need, and an increased circadian sensitivity to blue light contribute to the complaint of a delayed sleep schedule. These findings provide targets for strategies aiming to decreasing the severity of a sleep delay and the negative consequences on daytime functioning and health. Copyright © 2017 Elsevier B.V. All rights reserved.

  12. Plasma temperature during methylene blue/light treatment influences virus inactivation capacity and product quality.

    Science.gov (United States)

    Gravemann, U; Handke, W; Sumian, C; Alvarez, I; Reichenberg, S; Müller, T H; Seltsam, A

    2018-02-27

    Photodynamic treatment using methylene blue (MB) and visible light is in routine use for pathogen inactivation of human plasma in different countries. Ambient and product temperature conditions for human plasma during production may vary between production sites. The influence of different temperature conditions on virus inactivation capacity and plasma quality of the THERAFLEX MB-Plasma procedure was investigated in this study. Plasma units equilibrated to 5 ± 2°C, room temperature (22 ± 2°C) or 30 ± 2°C were treated with MB/light and comparatively assessed for the inactivation capacity for three different viruses, concentrations of MB and its photoproducts, activity of various plasma coagulation factors and clotting time. Reduced solubility of the MB pill was observed at 5 ± 2°C. Photocatalytic degradation of MB increased with increasing temperature, and the greatest formation of photoproducts (mainly azure B) occurred at 30 ± 2°C. Inactivation of suid herpesvirus, bovine viral diarrhoea virus and vesicular stomatitis virus was significantly lower at 5 ± 2°C than at higher temperatures. MB/light treatment affected clotting times and the activity of almost all investigated plasma proteins. Factor VIII (-17·7 ± 8·3%, 22 ± 2°C) and fibrinogen (-14·4 ± 16·4%, 22 ± 2°C) showed the highest decreases in activity. Increasing plasma temperatures resulted in greater changes in clotting time and higher losses of plasma coagulation factor activity. Temperature conditions for THERAFLEX MB-Plasma treatment must be carefully controlled to assure uniform quality of pathogen-reduced plasma in routine production. Inactivation of cooled plasma is not recommended. © 2018 International Society of Blood Transfusion.

  13. Protective effects of bilberry and lingonberry extracts against blue light-emitting diode light-induced retinal photoreceptor cell damage in vitro

    OpenAIRE

    Ogawa, Kenjirou; Kuse, Yoshiki; Tsuruma, Kazuhiro; Kobayashi, Saori; Shimazawa, Masamitsu; Hara, Hideaki

    2014-01-01

    Background Blue light is a high-energy or short-wavelength visible light, which induces retinal diseases such as age-related macular degeneration and retinitis pigmentosa. Bilberry (Vaccinium myrtillus L.) and lingonberry (Vaccinium vitis-idaea) contain high amounts of polyphenols (anthocyanins, resveratrol, and proanthocyanidins) and thus confer health benefits. This study aimed to determine the protective effects and mechanism of action of bilberry extract (B-ext) and lingonberry extract (L...

  14. Visual function improvement using photocromic and selective blue-violet light filtering spectacle lenses in patients affected by retinal diseases.

    Science.gov (United States)

    Colombo, L; Melardi, E; Ferri, P; Montesano, G; Samir Attaalla, S; Patelli, F; De Cillà, S; Savaresi, G; Rossetti, L

    2017-08-22

    To evaluate functional visual parameters using photocromic and selective blue-violet light filtering spectacle lenses in patients affected by central or peripheral scotoma due to retinal diseases. Sixty patients were enrolled in this study: 30 patients affected by central scotoma, group 1, and 30 affected by peripheral scotoma, group 2. Black on White Best Corrected Visual Acuity (BW-BCVA), White on Black Best Corrected Visual Acuity (WB-BCVA), Mars Contrast Sensitivity (CS) and a Glare Test (GT) were performed to all patients. Test results with blue-violet filter, a short-pass yellow filter and with no filters were compared. All scores from test results increased significantly with blue-violet filters for all patients. The mean BW-BCVA increased from 0.30 ± 0.20 to 0.36 ± 0.21 decimals in group 1 and from 0.44 ± 0.22 to 0.51 ± 0.23 decimals in group 2 (Mean ± SD, p Blue filter compared to Yellow filter in all tests (p blue-violet light filter showed functional benefit in all evaluated patients.

  15. Intensity of blue LED light: a potential stimulus for biomass and lipid content in fresh water microalgae Chlorella vulgaris.

    Science.gov (United States)

    Atta, Madiha; Idris, Ani; Bukhari, Ataullah; Wahidin, Suzana

    2013-11-01

    Light quality and the intensity are key factors which render microalgae as a potential source of biodiesel. In this study the effects of various intensities of blue light and its photoperiods on the growth and lipid content of Chlorella vulgaris were investigated by using LED (Light Emitting Diode) in batch culture. C. vulgaris was grown for 13 days at three different light intensities (100, 200 and 300 μmol m(-2)s(-1)). Effect of three different light and dark regimes (12:12, 16:08 and 24:00 h Light:Dark) were investigated for each light intensity at 25°C culture temperature. Maximum lipid content (23.5%) was obtained due to high efficiency and deep penetration of 200 μmol m(-2)s(-1) of blue light (12:12 L:D) with improved specific growth (1.26 d(-1)) within reduced cultivation time of 8 days. White light could produce 20.9% lipid content in 10 days at 16:08 h L:D. Copyright © 2013 Elsevier Ltd. All rights reserved.

  16. In vitro and in vivo Efficacy of New Blue Light Emitting Diode Phototherapy Compared to Conventional Halogen Quartz Phototherapy for Neonatal Jaundice

    OpenAIRE

    Chang, Yun Sil; Hwang, Jong Hee; Kwon, Hyuk Nam; Choi, Chang Won; Ko, Sun Young; Park, Won Soon; Shin, Son Moon; Lee, Munhyang

    2005-01-01

    High intensity light emitting diodes (LEDs) are being studied as possible light sources for the phototherapy of neonatal jaundice, as they can emit high intensity light of narrow wavelength band in the blue region of the visible light spectrum corresponding to the spectrum of maximal bilirubin absorption. We developed a prototype blue gallium nitride LED phototherapy unit with high intensity, and compared its efficacy to commercially used halogen quartz phototherapy device by measuring both i...

  17. Binding investigation on the interaction between Methylene Blue (MB)/TiO2 nanocomposites and bovine serum albumin by resonance light-scattering (RLS) technique and fluorescence spectroscopy.

    Science.gov (United States)

    Li, Yuesheng; Zhang, Yue; Sun, Shaofa; Zhang, Aiqing; Liu, Yi

    2013-11-05

    The interaction between Methylene Blue (MB)/TiO2 nanocomposites and bovine serum albumin (BSA) was investigated by resonance light scattering (RLS), fluorescence, three-dimension spectra and UV-vis absorbance spectroscopy. Several factors which may influence the RLS intensity were also investigated before characterizing MB/TiO2-BSA complex. It was proved that the mechanism of MB/TiO2 nanocomposites binding to BSA was mainly a result of the formation of MB/TiO2-BSA complex. The binding constant of MB/TiO2-BSA is 0.762 × 10(-5) L mol(-1) at 298K. By calculating the binding constant at different temperature, the thermodynamic parameters ΔH, ΔG, and ΔS can be observed and deduced that the hydrophobic interactions played an important role to stabilize the complex. The distance r (3.73 nm) between donor (BSA) and acceptor (MB/TiO2) was obtained according to fluorescence resonance energy transfer (FRET). The binding site for MB/TiO2 on BSA was mainly located in sub-domain IIA. The UV-vis absorbance, circular dichroism and three dimension fluorescence have also been used to investigate the effect of MB/TiO2 on the conformation of BSA. Copyright © 2013 Elsevier B.V. All rights reserved.

  18. Organic matrix effects on the formation of light-absorbing compounds from α-dicarbonyls in aqueous salt solution.

    Science.gov (United States)

    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.

  19. Super-hydrophilic copper sulfide films as light absorbers for efficient solar steam generation under one sun illumination

    Science.gov (United States)

    Guo, Zhenzhen; Ming, Xin; Wang, Gang; Hou, Baofei; Liu, Xinghang; Mei, Tao; Li, Jinhua; Wang, Jianying; Wang, Xianbao

    2018-02-01

    Solar steam technology is one of the simplest, most direct and effective ways to harness solar energy through water evaporation. Here, we report the development using super-hydrophilic copper sulfide (CuS) films with double-layer structures as light absorbers for solar steam generation. In the double-layer structure system, a porous mixed cellulose ester (MCE) membrane is used as a supporting layer, which enables water to get into the CuS light absorbers through a capillary action to provide continuous water during solar steam generation. The super-hydrophilic property of the double-layer system (CuS/MCE) leads to a thinner water film close to the air-water interface where the surface temperature is sufficiently high, leading to more efficient evaporation (∼80 ± 2.5%) under one sun illumination. Furthermore, the evaporation efficiencies still keep a steady value after 15 cycles of testing. The super-hydrophilic CuS film is promising for practical application in water purification and evaporation as a light absorption material.

  20. Determination of light-absorbing layers at inner capillary surface by cw excitation crossed-beam thermal-lens spectrometry.

    Science.gov (United States)

    Nedosekin, D A; Faubel, W; Proskurnin, M A; Pyell, U

    2009-05-15

    A thermal-lens spectrometric unit suitable for selective quantitative measurements of light-absorbing layers adsorbed onto the inner surface of a quartz glass capillary is described. The quantitative description of the thermal-lens signal generated in a quartz glass capillary with a light-absorbing layer at the inner surface of capillary is developed, which is based on the description for the thermal-lens experiment in the layered solids presented elsewhere. The accuracy of calculations is demonstrated by the comparison of predicted results with the experimental data and those predicted by the conventional theory. The data achieved prove the accuracy of calculations both for the time dependent thermal-lens signal and for the lock-in amplifier signal under variation of the spectrometer configuration for capillaries having an adsorbed layer. The proposed technique is used for the investigation of chromate/2,10-ionene and 4-aminoazobenzene adsorption at capillary walls. The estimates of the minimum light absorption detectable at capillary walls are at a level of 1 x 10(-5) abs. units; the linear range of the thermal-lens signal from the inner surface layer no less than three orders of magnitude is predicted.

  1. Arctic climate response to forcing from light-absorbing particles in snow and sea ice in CESM

    Directory of Open Access Journals (Sweden)

    N. Goldenson

    2012-09-01

    Full Text Available 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. Efficient white phosphorescent organic light-emitting diodes consisting of orange ultrathin and blue mixed host emission layers

    Science.gov (United States)

    Sheng, Ren; Zuo, Liangmei; Xue, Kaiwen; Duan, Yu; Chen, Ping; Cheng, Gang; Zhao, Yi

    2016-08-01

    We have successfully demonstrated highly efficient white phosphorescent organic light-emitting diodes (OLEDs) by inserting an ultrathin non-doped orange layer within blue mixed host emission layer. The key feature of the novel device is the employment of blue mixed host and orange ultrathin layers, resulting in an extended recombination region and more balanced charge carrier. The maximum efficiencies of 33.8 lm W-1 and 32.2 cd A-1 are obtained. Moreover, the resulting white device achieves a slight efficiency roll-off and a high luminance at low operating voltage. Our versatile concept suggests a promising simple method to achieve high performance white OLEDs.

  3. A train of blue light pulses delivered through closed eyelids suppresses melatonin and phase shifts the human circadian system

    Directory of Open Access Journals (Sweden)

    Figueiro MG

    2013-10-01

    Full Text Available Mariana G Figueiro, Andrew Bierman, Mark S ReaLighting Research Center, Rensselaer Polytechnic Institute, Troy, NY, USAAbstract: A model of circadian phototransduction was published in 2005 to predict the spectral sensitivity of the human circadian system to narrow-band and polychromatic light sources by combining responses to light from the spectral-opponent “blue” versus “yellow” cone bipolar pathway with direct responses to light by the intrinsically photosensitive retinal ganglion cells. In the model, depolarizing “blue” responses, but not hyperpolarizing “yellow” responses, from the “blue” versus “yellow” pathway are combined with the intrinsically photosensitive retinal ganglion cell responses. Intrinsically photosensitive retinal ganglion cell neurons are known to be much slower to respond to light than the cone pathway, so an implication of the model is that periodic flashes of “blue” light, but not “yellow” light, would be effective for stimulating the circadian system. A within-subjects study was designed to test the implications of the model regarding retinal exposures to brief flashes of light. The study was also aimed at broadening the foundation for clinical treatment of circadian sleep disorders by delivering flashing light through closed eyelids while people were asleep. In addition to a dark control night, the eyelids of 16 subjects were exposed to three light-stimulus conditions in the phase delay portion of the phase response curve while they were asleep: (1 2-second flashes of 111 W/m2 of blue (λmax ≈ 480 nm light once every minute for 1 hour, (2 131 W/m2 of green (λmax ≈ 527 nm light, continuously on for 1 hour, and (3 2-second flashes of the same green light once every minute for 1 hour. Inferential statistics showed that the blue flash light-stimulus condition significantly delayed circadian phase and significantly suppressed nocturnal melatonin. The results of this study further our

  4. Effects of Daytime Exposure to Light from Blue-Enriched Light-Emitting Diodes on the Nighttime Melatonin Amplitude and Circadian Regulation of Rodent Metabolism and Physiology.

    Science.gov (United States)

    Dauchy, Robert T; Wren-Dail, Melissa A; Hoffman, Aaron E; Hanifin, John P; Warfield, Benjamin; Brainard, George C; Hill, Steven M; Belancio, Victoria P; Dauchy, Erin M; Blask, David E

    2016-01-01

    Regular cycles of exposure to light and dark control pineal melatonin production and temporally coordinate circadian rhythms of metabolism and physiology in mammals. Previously we demonstrated that the peak circadian amplitude of nocturnal blood melatonin levels of rats were more than 6-fold higher after exposure to cool white fluorescent (CWF) light through blue-tinted (compared with clear) rodent cages. Here, we evaluated the effects of light-phase exposure of rats to white light-emitting diodes (LED), which emit light rich in the blue-appearing portion of the visible spectrum (465-485 nm), compared with standard broadspectrum CWF light, on melatonin levels during the subsequent dark phase and on plasma measures of metabolism and physiology. Compared with those in male rats under a 12:12-h light:dark cycle in CWF light, peak plasma melatonin levels at the middark phase (time, 2400) in rats under daytime LED light were over 7-fold higher, whereas midlight phase levels (1200) were low in both groups. Food and water intakes, body growth rate, and total fatty acid content of major metabolic tissues were markedly lower, whereas protein content was higher, in the LED group compared with CWF group. Circadian rhythms of arterial plasma levels of total fatty acids, glucose, lactic acid, pO 2 , pCO 2 , insulin, leptin, and corticosterone were generally lower in LED-exposed rats. Therefore, daytime exposure of rats to LED light with high blue emissions has a marked positive effect on the circadian regulation of neuroendocrine, metabolic, and physiologic parameters associated with the promotion of animal health and wellbeing and thus may influence scientific outcomes.

  5. Visible light-induced photocatalytic degradation of Reactive Blue-19 over highly efficient polyaniline-TiO2nanocomposite: a comparative study with solar and UV photocatalysis.

    Science.gov (United States)

    Kalikeri, Shankramma; Kamath, Nidhi; Gadgil, Dhanashri Jayant; Shetty Kodialbail, Vidya

    2018-02-01

    Polyaniline-TiO 2 (PANI-TiO 2 ) nanocomposite was prepared by in situ polymerisation method. X-ray diffractogram (XRD) showed the formation of PANI-TiO 2 nanocomposite with the average crystallite size of 46 nm containing anatase TiO 2 . The PANI-TiO 2 nanocomposite consisted of short-chained fibrous structure of PANI with spherical TiO 2 nanoparticles dispersed at the tips and edge of the fibres. The average hydrodynamic diameter of the nanocomposite was 99.5 nm. The band gap energy was 2.1 eV which showed its ability to absorb light in the visible range. The nanocomposite exhibited better visible light-mediated photocatalytic activity than TiO 2 (Degussa P25) in terms of degradation of Reactive Blue (RB-19) dye. The photocatalysis was favoured under initial acidic pH, and complete degradation of 50 mg/L dye could be achieved at optimum catalyst loading of 1 g/L. The kinetics of degradation followed the Langmuir-Hinshelhood model. PANI-TiO 2 nanocomposite showed almost similar photocatalytic activity under UV and visible light as well as in the solar light which comprises of radiation in both UV and visible light range. Chemical oxygen demand removal of 86% could also be achieved under visible light, confirming that simultaneous mineralization of the dye occurred during photocatalysis. PANI-TiO 2 nanocomposites are promising photocatalysts for the treatment of industrial wastewater containing RB-19 dye.

  6. Antimicrobial blue light therapy for multidrug-resistant Acinetobacter baumannii infection in a mouse burn model: implications for prophylaxis and treatment of combat-related wound infections.

    Science.gov (United States)

    Zhang, Yunsong; Zhu, Yingbo; Gupta, Asheesh; Huang, Yingying; Murray, Clinton K; Vrahas, Mark S; Sherwood, Margaret E; Baer, David G; Hamblin, Michael R; Dai, Tianhong

    2014-06-15

    In this study, we investigated the utility of antimicrobial blue light therapy for multidrug-resistant Acinetobacter baumannii infection in a mouse burn model. A bioluminescent clinical isolate of multidrug-resistant A. baumannii was obtained. The susceptibility of A. baumannii to blue light (415 nm)-inactivation was compared in vitro to that of human keratinocytes. Repeated cycles of sublethal inactivation of bacterial by blue light were performed to investigate the potential resistance development of A. baumannii to blue light. A mouse model of third degree burn infected with A. baumannii was developed. A single exposure of blue light was initiated 30 minutes after bacterial inoculation to inactivate A. baumannii in mouse burns. It was found that the multidrug-resistant A. baumannii strain was significantly more susceptible than keratinocytes to blue light inactivation. Transmission electron microscopy revealed blue light-induced ultrastructural damage in A. baumannii cells. Fluorescence spectroscopy suggested that endogenous porphyrins exist in A. baumannii cells. Blue light at an exposure of 55.8 J/cm(2) significantly reduced the bacterial burden in mouse burns. No resistance development to blue light inactivation was observed in A. baumannii after 10 cycles of sublethal inactivation of bacteria. No significant DNA damage was detected in mouse skin by means of a skin TUNEL assay after a blue light exposure of 195 J/cm(2). © The Author 2014. Published by Oxford University Press on behalf of the Infectious Diseases Society of America. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

  7. Multilayer tungsten-alumina-based broadband light absorbers for high-temperature applications

    DEFF Research Database (Denmark)

    Chirumamilla, Manohar; Roberts, Alexander Sylvester; Ding, Fei

    2016-01-01

    Efficient broadband absorption of visible and near-infrared light by low quality-factor metal-insulator-metal (MIM) resonators using refractory materials is reported. Omnidirectional absorption of incident light for broad angles of incidence and polarization insensitivity are observed...

  8. Female Sprague Dawley Rats Show Impaired Spatial Memory in the 8-Arm Radial Maze under Dim Blue and Red Light

    OpenAIRE

    Pirchl, Michael; Kemmler, Georg; Humpel, Christian

    2010-01-01

    Light intensity and wavelength strongly influence mood and cognition in humans and rodent animal models. The aim of the present study was to explore if dim white (7.6–17.7 lux) , blue (1.3–2.3 lux), and red light (0.8–1.4 lux) affect spatial memory of male and female Sprague Dawley rats in the 8-arm radial maze. Our data show that spatial memory significantly improved within 5 daily learning sessions (each 5 trials) under dim white light, which was not different between male and female rats. ...

  9. Mechanism of blue-light-induced plasma-membrane depolarization in etiolated cucumber hypocotyls

    Science.gov (United States)

    Spalding, E. P.; Cosgrove, D. J.

    1992-01-01

    A large, transient depolarization of the plasma membrane precedes the rapid blue-light (BL)-induced growth suppression in etiolated seedlings of Cucumis sativus L. The mechanism of this voltage transient was investigated by applying inhibitors of ion channels and the plasma-membrane H(+)-ATPase, by manipulating extracellular ion concentrations, and by measuring cell input resistance and ATP levels. The depolarizing phase was not affected by Ca(2+)-channel blockers (verapamil, La3+) or by reducing extracellular free Ca2+ by treatment with ethylene glycol-bis(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid (EGTA). However, these treatments did reduce the rate of repolarization, indicating an inward movement of Ca2+ is involved. No effects of the K(+)-channel blocker tetraethylammonium (TEA+) were detected. Vanadate and KCN, used to inhibit the H(+)-ATPase, reduced or completely inhibited the BL-induced depolarization. Levels of ATP increased by 11-26% after 1-2 min of BL. Input resistance of trichrome cells, measured with double-barreled microelectrodes, remained constant during the onset of the depolarization but decreased as the membrane voltage became more positive than -90 mV. The results indicate that the depolarization mechanism initially involves inactivation of the H(+)-ATPase with subsequent transient activation of one or more types of ion channels.

  10. Photocatalytic degradation of methylene blue by nanostructured Fe/FeS powder under visible light

    Science.gov (United States)

    Esmaili, Hassan; Kotobi, Amir; Sheibani, Saeed; Rashchi, Fereshteh

    2018-02-01

    The photocatalytic performance of mechano-thermally synthesized Fe/FeS nanostructures formed from micron-sized starting materials was compared with that of a thermally synthesized nanostructure with nano-sized precursors in this paper. The properties of as-synthesized materials were studied by X-ray diffraction (XRD), transmission electron microscopy (TEM), vibrating sample magnetometry (VSM), diffuse reflectance spectroscopy (DRS), and ultraviolet-visible (UV-Vis) spectroscopy. The effects of irradiation time, methylene blue (MB) concentration, catalyst dosage, and pH value upon the degradation of MB were studied. Magnetic properties of the samples showed that both as-synthesized Fe/FeS photocatalysts are magnetically recoverable, eliminating the need for conventional filtration steps. Degradation of 5 ppm of the MB solution by mechano-thermally synthesized Fe/FeS with a photocatalyst dosage of 1 kg/m3 at pH 11 can reach 96% after 12 ks irradiation under visible light. The photocatalytic efficiency is higher in alkaline solution. The kinetics of photocatalytic degradation in both samples is controlled by a first-order reaction. However, the rate-constant value in the thermally synthesized Fe/FeS photocatalyst sample is only 1.5 times greater than that of the mechano-thermally synthesized one.

  11. Photoinhibition of stem elongation by blue and red light: effects on hydraulic and cell wall properties

    Science.gov (United States)

    Kigel, J.; Cosgrove, D. J.

    1991-01-01

    The underlying mechanism of photoinhibition of stem elongation by blue (BL) and red light (RL) was studied in etiolated seedlings of pea (Pisum sativum L. cv Alaska). Brief BL irradiations resulted in fast transient inhibition of elongation, while a delayed (lag approximately 60 minutes) but prolonged inhibition was observed after brief RL. Possible changes in the hydraulic and wall properties of the growing cells during photoinhibition were examined. Cell sap osmotic pressure was unaffected by BL and RL, but both irradiations increased turgor pressure by approximately 0.05 megapascal (pressure-probe technique). Cell wall yielding was analyzed by in vivo stress relaxation (pressure-block technique). BL and RL reduced the initial rate of relaxation by 38 and 54%, while the final amount of relaxation was decreased by 48 and 10%, respectively. These results indicate that RL inhibits elongation mainly by lowering the wall yi