Science.gov

Sample records for absorbs blue light

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

    PubMed

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

    2015-05-01

    Plants synthesize phenolic compounds in response to certain environmental signals or stresses. One large group of phenolics, flavonoids, is considered particularly responsive to ultraviolet (UV) radiation. However, here we demonstrate that solar blue light stimulates flavonoid biosynthesis in the absence of UV-A and UV-B radiation. We grew pea plants (Pisum sativum cv. Meteor) outdoors, in Finland during the summer, under five types of filters differing in their spectral transmittance. These filters were used to (1) attenuate UV-B; (2) attenuate UV-B and UV-A < 370 nm; (3) attenuate UV-B and UV-A; (4) attenuate UV-B, UV-A and blue light; and (5) as a control not attenuating these wavebands. Attenuation of blue light significantly reduced the flavonoid content in leaf adaxial epidermis and reduced the whole-leaf concentrations of quercetin derivatives relative to kaempferol derivatives. In contrast, UV-B responses were not significant. These results show that pea plants regulate epidermal UV-A absorbance and accumulation of individual flavonoids by perceiving complex radiation signals that extend into the visible region of the solar spectrum. Furthermore, solar blue light instead of solar UV-B radiation can be the main regulator of phenolic compound accumulation in plants that germinate and develop outdoors. PMID:25040832

  2. Visible light broadband perfect absorbers

    NASA Astrophysics Data System (ADS)

    Jia, X. L.; Meng, Q. X.; Yuan, C. X.; Zhou, Z. X.; Wang, X. O.

    2016-03-01

    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.

  3. Hazards of solar blue light

    SciTech Connect

    Okuno, Tsutomu

    2008-06-01

    Short-wavelength visible light (blue light) of the Sun has caused retinal damage in people who have stared fixedly at the Sun without adequate protection. The author quantified the blue-light hazard of the Sun according to the International Commission on Non-Ionizing Radiation Protection (ICNIRP) guidelines by measuring the spectral radiance of the Sun. The results showed that the exposure limit for blue light can be easily exceeded when people view the Sun and that the solar blue-light hazard generally increases with solar elevation, which is in accordance with a model of the atmospheric extinction of sunlight. Viewing the Sun can be very hazardous and therefore should be avoided except at very low solar elevations.

  4. Damage tolerant light absorbing material

    DOEpatents

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

    1993-09-07

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

  5. Damage tolerant light absorbing material

    DOEpatents

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

    1993-01-01

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

  6. Blue light hazard and aniridia.

    PubMed Central

    Abadi, R. V.; Dickinson, C. M.

    1985-01-01

    The fundi of three patients with aniridia were photographed with a 470 nm illuminating light source. No apparent change in contrast was observable throughout the macular region. This would suggest an absence of the macular pigment. The likelihood of aniridics being more susceptible than normal persons to blue light damage is discussed. Images PMID:3978071

  7. The Cryptochrome Blue Light Receptors.

    PubMed

    Yu, Xuhong; Liu, Hongtao; Klejnot, John; Lin, Chentao

    2010-09-23

    Cryptochromes are photolyase-like blue light receptors originally discovered in Arabidopsis but later found in other plants, microbes, and animals. Arabidopsis has two cryptochromes, CRY1 and CRY2, which mediate primarily blue light inhibition of hypocotyl elongation and photoperiodic control of floral initiation, respectively. In addition, cryptochromes also regulate over a dozen other light responses, including circadian rhythms, tropic growth, stomata opening, guard cell development, root development, bacterial and viral pathogen responses, abiotic stress responses, cell cycles, programmed cell death, apical dominance, fruit and ovule development, seed dormancy, and magnetoreception. Cryptochromes have two domains, the N-terminal PHR (Photolyase-Homologous Region) domain that bind the chromophore FAD (flavin adenine dinucleotide), and the CCE (CRY C-terminal Extension) domain that appears intrinsically unstructured but critical to the function and regulation of cryptochromes. Most cryptochromes accumulate in the nucleus, and they undergo blue light-dependent phosphorylation or ubiquitination. It is hypothesized that photons excite electrons of the flavin molecule, resulting in redox reaction or circular electron shuttle and conformational changes of the photoreceptors. The photoexcited cryptochrome are phosphorylated to adopt an open conformation, which interacts with signaling partner proteins to alter gene expression at both transcriptional and posttranslational levels and consequently the metabolic and developmental programs of plants. PMID:21841916

  8. Morphological responses of wheat to blue light

    NASA Technical Reports Server (NTRS)

    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.

  9. Blue enhanced light sources: opportunities and risks

    NASA Astrophysics Data System (ADS)

    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.

  10. Light extraction improvement of blue light-emitting diodes with a Metal-distributed Bragg reflector current blocking layer

    NASA Astrophysics Data System (ADS)

    Liu, Na; Yi, Xiaoyan; Wang, Li; Sun, Xuejiao; Liu, Lei; Liu, Zhiqiang; Wang, Junxi; Li, Jinmin

    2015-03-01

    The p-electrode of blue light-emitting diodes (LED) chips has a low transmittance on the blue light spectrum. The blue light emitted from the quantum wells under the p-electrode will be severely absorbed by p-electrode, which cause a decrease in blue light extraction efficiency (LEE). In this study, we first designed a current blocking layer (CBL) structure with the blue light reflection through the simulation software. The simulation results show that this structure can effectively improve blue LEE, and then, this structure was verified by experiment. Electroluminescence measurement results show that LED with Metal-distributed Bragg reflector (M-DBR) CBL exhibited better optical performance than the LED with SiO2 CBL and DBR CBL. It was found that M-DBR CBL can effectively increase the blue light reflectivity and prevent the light absorption from the metal p-electrode to improve LED' blue LEE.

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

    PubMed

    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. PMID:27039979

  12. Retinal Effects Of Blue Light Exposure

    NASA Astrophysics Data System (ADS)

    Ham, William T.; Mueller, Harold A.; Ruffolo, J. J.

    1980-10-01

    Recent research has shown that blue light exposure is an important factor in certain types of retinal injury. The mammalian ocular media transmits the spectral band 400-1400 nm to the retina. The short wavelengths (400-550 nm) produce a photochemical or actinic type of damage, while the longer wavelengths (550-1400 nm) produce thermal damage. Distinction between the two types of retinal damage are discussed briefly and the importance of the blue light effect for solar retinitis and eclipse blindness is emphasized. The significance of blue light retinal injury is summarized for various environmental and occupational exposures.

  13. Blue light emitting thiogallate phosphor

    DOEpatents

    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.

  14. Cylinder light concentrator and absorber: theoretical description.

    PubMed

    Kildishev, Alexander V; Prokopeva, Ludmila J; Narimanov, Evgenii E

    2010-08-01

    We present a detailed theoretical description of a broadband omnidirectional light concentrator and absorber with cylinder geometry. The proposed optical "trap" captures nearly all the incident light within its geometric cross-section, leading to a broad range of possible applications--from solar energy harvesting to thermal light emitters and optoelectronic components. We have demonstrated that an approximate lamellar black-hole with a moderate number of homogeneous layers, while giving the desired ray-optical performance, can provide absorption efficiencies comparable to those of ideal devices with a smooth gradient in index. PMID:20721056

  15. Blue light inhibits proliferation of melanoma cells

    NASA Astrophysics Data System (ADS)

    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.

  16. Luminescence conversion of blue light emitting diodes

    NASA Astrophysics Data System (ADS)

    Schlotter, P.; Schmidt, R.; Schneider, J.

    Using blue-emitting GaN/6HSiC chips as primary light sources, we have fabricated green, yellow, red and white emitting LEDs. The generation of mixed colors, as turquoise and magenta is also demonstrated. The underlying physical principle is that of luminescence down-conversion (Stokes shift), as typical for organic luminescent dye molecules. A white emitting LED, using an inorganic converter, Y3Al5O12:Ce3+( ), has also been realized.

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

    NASA Technical Reports Server (NTRS)

    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.

  18. Is blue light good or bad for plants?

    PubMed

    Dougher, T A; Bugbee, B G

    1998-01-01

    Blue photons are energetically expensive so the most energy-efficient lamps contain the least blue light. Blue photons are not used efficiently in photosynthesis, but blue light has dramatic effects on plant development. We studied the growth and development of soybean, wheat, and lettuce plants under high-pressure sodium and metal halide lamps with yellow filters creating five fractions of blue light (0.5%, 3.5%, 6%, 1 8%, and 26% blue) at 500 micromoles m-2 s-1 and (< 0.1%, 1.7%, 6%, 12%, and 26%) at 200 mol m-2 s-1. The response was species dependent. Lettuce was highly sensitive to blue light fraction and had an optimum dry weight and leaf area at about 6% blue, but results were complicated by sensitivity to lamp type. Wheat and soybean were less sensitive to blue light, but dry mass and leaf area decreased steadily with increasing blue light. Blue light fraction significantly affected specific leaf area (SLA, m2 kg-1) and chlorophyll in lettuce, but had no significant effect on wheat and soybeans. The data suggest that lettuce benefits from some added blue light, but soybean and wheat may not. PMID:11541668

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

    PubMed Central

    Cho, M H; Spalding, E P

    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. PMID:8755616

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

    NASA Technical Reports Server (NTRS)

    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.

  1. High-precision temperature determination of evaporating light-absorbing and non-light-absorbing droplets.

    PubMed

    Derkachov, G; Jakubczyk, D; Woźniak, M; Archer, J; Kolwas, M

    2014-10-30

    Models describing evaporation or condensation of a droplet have existed for over a century, and the temporal evolutions of droplet radius and temperature could be predicted. However, the accuracy of results was questionable, since the models contain free parameters and the means of accurate calibration were not available. In previous work (Hołyst et al. Soft Matter 2013, 9, 7766), a model with an efficacious parametrization in terms of the mean free path was proposed and calibrated with molecular dynamics numerical experiment. It was shown that it is essentially possible to determine reliably the temperature of a steadily evaporating/condensing homogeneous droplet relative to ambient temperature when the evolution of the droplet radius is known. The accuracy of such measurement can reach fractions of mK. In the case of an evaporating droplet of pure liquid, the (droplet) temperature is constant during the stationary stage of evaporation. In this paper, we show that, in many cases, it is also possible to determine the temporal evolution of droplet temperature from the evolution of the droplet radius if the droplet (initial) composition is known. We found the droplet radius evolution with high accuracy and obtained the evolution of droplet temperature (and composition) for droplets of (i) a two-component mixture of pure liquids; (ii) solutions of solid in liquid, one that is non-surface-active and another that is; and (iii) suspensions of non-light-absorbing and light-absorbing particles. PMID:25290035

  2. Different Structural Changes Occur in the Blue- and Green-Absorbing Proteorhodopsin During the Primary Photoreaction†

    PubMed Central

    Amsden, Jason J.; Kralj, Joel M.; Bergo, Vladislav B.; Spudich, Elena N.; Spudich, John L.; Rothschild, Kenneth J.

    2013-01-01

    We examine the structural changes during the primary photoreaction in blue-absorbing proteorhodopsin (BPR), a light-driven retinylidene proton pump, using low-temperature FTIR difference spectroscopy. Comparison of the light induced BPR difference spectrum recorded at 80 K to that of green-absorbing proteorhodopsin (GPR) reveals that there are several differences in the BPR and GPR primary photoreactions despite the similar structure of the retinal chromophore and all-trans → 13-cis isomerization. Strong bands near 1700 cm−1 assigned previously to a change in hydrogen bonding of Asn230 in GPR are still present in BPR but in addition bands in the same region are assigned on the basis of site-directed mutagenesis to changes occurring in Gln105. In the amide II region bands are assigned on the basis of total-N15 labeling to structural changes of the protein backbone, although no such bands were previously observed for GPR. A band at 3642 cm−1 in BPR, assigned to the OH stretching mode of a water molecule on the basis of H218O substitution, appears at a different frequency than a band at 3626 cm−1 previously assigned to a water molecule in GPR. However, the substitution of Gln105 for Leu105 in BPR leads to the appearance of both bands at 3642 and 3626 cm−1 indicating the waters assigned in BPR and GPR exist in separate distinct locations and can coexist in the GPR-like Q105L mutant of BPR. These results indicate that there exist significant differences in the conformational changes occurring in these two types proteorhodopsin during the initial photoreaction despite their similar chromophores structures, which might reflect a different arrangement of water in the active site as well as substitution of a hydrophilic for hydrophobic residue at residue 105. PMID:18842006

  3. Novel Ultraviolet Light Absorbing Polymers For Optical Applications

    NASA Astrophysics Data System (ADS)

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

    1988-07-01

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

  4. Blue Light Protects Against Temporal Frequency Sensitive Refractive Changes

    PubMed Central

    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 < 0.03, all) and on temporal frequency (P < 0.03, all). In the presence of 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 < 0.003). Overall, neonatal astigmatism was reduced with 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

  5. Blue light is essential for high light acclimation and photoprotection in the diatom Phaeodactylum tricornutum

    PubMed Central

    Wilhelm, Christian

    2013-01-01

    The objective of the present study was to test the hypothesis that the acclimation to different light intensities in the diatom Phaeodactylum tricornutum is controlled by light quality perception mechanisms. Therefore, semi-continuous cultures of P. tricornutum were illuminated with equal amounts of photosynthetically absorbed radiation of blue (BL), white (WL), and red light (RL) and in combination of two intensities of irradiance, low (LL) and medium light (ML). Under LL conditions, growth rates and photosynthesis rates were similar for all cultures. However, BL cultures were found to be in an acclimation state with an increased photoprotective potential. This was deduced from an increased capacity of non-photochemical quenching, a larger pool of xanthophyll cycle pigments, and a higher de-epoxidation state of xanthophyll cycle pigments compared to WL and RL cultures. Furthermore, in the chloroplast membrane proteome of BL cells, an upregulation of proteins involved in photoprotection, e.g. the Lhcx1 protein and zeaxanthin epoxidase, was evident. ML conditions induced increased photosynthesis rates and a further enhanced photoprotective potential for algae grown under BL and WL. In contrast, RL cultures exhibited no signs of acclimation towards increased irradiance. The data implicate that in diatoms the photoacclimation to high light intensities requires the perception of blue light. PMID:23183259

  6. Beat the Winter Blues: Shedding Light on Seasonal Sadness

    MedlinePlus

    ... exit disclaimer . Subscribe Beat the Winter Blues Shedding Light on Seasonal Sadness As the days get shorter, ... clock” responds to cues in your surroundings, especially light and darkness. During the day, your brain sends ...

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

    NASA Technical Reports Server (NTRS)

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

    2003-01-01

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

  8. Circadian Rhythms in Stomatal Responsiveness to Red and Blue Light.

    PubMed Central

    Gorton, H. L.; Williams, W. E.; Assmann, S. M.

    1993-01-01

    Stomata of many plants have circadian rhythms in responsiveness to environmental cues as well as circadian rhythms in aperture. Stomatal responses to red light and blue light are mediated by photosynthetic photoreceptors; responses to blue light are additionally controlled by a specific blue-light photoreceptor. This paper describes circadian rhythmic aspects of stomatal responsiveness to red and blue light in Vicia faba. Plants were exposed to a repeated light:dark regime of 1.5:2.5 h for a total of 48 h, and because the plants could not entrain to this short light:dark cycle, circadian rhythms were able to "free run" as if in continuous light. The rhythm in the stomatal conductance established during the 1.5-h light periods was caused both by a rhythm in sensitivity to light and by a rhythm in the stomatal conductance established during the preceding 2.5-h dark periods. Both rhythms peaked during the middle of the subjective day. Although the stomatal response to blue light is greater than the response to red light at all times of day, there was no discernible difference in period, phase, or amplitude of the rhythm in sensitivity to the two light qualities. We observed no circadian rhythmicity in net carbon assimilation with the 1.5:2.5 h light regime for either red or blue light. In continuous white light, small rhythmic changes in photosynthetic assimilation were observed, but at relatively high light levels, and these appeared to be attributable largely to changes in internal CO2 availability governed by stomatal conductance. PMID:12231947

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

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

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

  10. Enhanced blue light shielding property of light-diffusion polycarbonate composites by CeO2-coated silicate microspheres

    NASA Astrophysics Data System (ADS)

    Zhao, Yu; Shi, Liyi; Tang, Anjie; Song, Na; Tang, Shengfu; Ding, Peng

    2015-07-01

    The CeO2 coated silicate microspheres (SMSs) core-shell particles (SMS-CeO2) were synthesized for enhancing blue light shielding property of polycarbonate (PC) composites. The structure analysis showed that CeO2 particles were homogenously coated on SMS by Ce-O-Si bonds. The optical analysis indicated that the transmittance of PC/SMS-CeO2 composites were enhanced to 63.2% from 42.9% for PC/SMS/CeO2 composites when 0.6 wt.% fillers were loaded, while there was no obvious influence on the haze of the composites. UV-Vis analysis showed that the absorbance at 450-nm wavelength of blue-light increased from 24% of PC/SMS to 50% of PC/SMS-CeO2 composites, while the absorbance at 650-nm wavelength of red-light was unchanged. These results indicated that the PC/SMS-CeO2 composites had blue light shielding property and better performance on transmitting other visible lights.

  11. Brain Responses to Violet, Blue, and Green Monochromatic Light Exposures in Humans: Prominent Role of Blue Light and the Brainstem

    PubMed Central

    Vandewalle, Gilles; Schmidt, Christina; Albouy, Geneviève; Sterpenich, Virginie; Darsaud, Annabelle; Rauchs, Géraldine; Berken, Pierre-Yves; Balteau, Evelyne; Degueldre, Christian; Luxen, André; Maquet, Pierre; Dijk, Derk-Jan

    2007-01-01

    Background Relatively long duration retinal light exposure elicits nonvisual responses in humans, including modulation of alertness and cognition. These responses are thought to be mediated in part by melanopsin-expressing retinal ganglion cells which are more sensitive to blue light than violet or green light. The contribution of the melanopsin system and the brain mechanisms involved in the establishment of such responses to light remain to be established. Methodology/Principal Findings We exposed 15 participants to short duration (50 s) monochromatic violet (430 nm), blue (473 nm), and green (527 nm) light exposures of equal photon flux (1013ph/cm2/s) while they were performing a working memory task in fMRI. At light onset, blue light, as compared to green light, increased activity in the left hippocampus, left thalamus, and right amygdala. During the task, blue light, as compared to violet light, increased activity in the left middle frontal gyrus, left thalamus and a bilateral area of the brainstem consistent with activation of the locus coeruleus. Conclusion/Significance These results support a prominent contribution of melanopsin-expressing retinal ganglion cells to brain responses to light within the very first seconds of an exposure. The results also demonstrate the implication of the brainstem in mediating these responses in humans and speak for a broad involvement of light in the regulation of brain function. PMID:18043754

  12. Blue light-activated hypocrellin B damages ovarian cancer cells

    NASA Astrophysics Data System (ADS)

    Jiang, Y.; Leung, A. W. N.; Xiang, J. Y.; Xu, C. S.

    2011-10-01

    In the present study, a novel blue light source from LED was used to activate hypocrellin B in ovarian cancer HO-8910 cells. Hyppcrellin B concentration was kept at 2.5 μM and light doses from 0.5-4.0 J/cm2. Photocytotoxicity was investigated using MTT reduction assay and light microscopy after light irradiation. Cellular morphology was observed using transmission electron microscopy (TEM). MTT assay showed that the cytotoxicity of blue light-activated hypocrellin B in HO-8910 cells increased along with light dose. The observations from light microscopy reinforced the above results. TEM showed that microvillin disappearance, vacuole formation, chromatin condensation, and topical apoptotic body were observed in the cells treated by both light and hypocrellin B. The findings demonstrated that blue light from LED source could effectively activate hypocrellin B to cause the destruction of HO-8910 cells, indicating that Blue light-activated hypocrellin B might be potential therapeutic strategy in the management of ovarian cancer.

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

    PubMed Central

    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. The Effects of Blue Light on Ocular Health.

    ERIC Educational Resources Information Center

    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…

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

    PubMed

    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. PMID:27033206

  16. Blue light irradiation suppresses dendritic cells activation in vitro.

    PubMed

    Fischer, Michael R; Abel, Manuela; Lopez Kostka, Susanna; Rudolph, Berenice; Becker, Detlef; von Stebut, Esther

    2013-08-01

    Blue light is a UV-free irradiation suitable for treating chronic skin inflammation, for example, atopic dermatitis, psoriasis, and hand- and foot eczema. However, a better understanding of the mode of action is still missing. For this reason, we investigated whether dendritic cells (DC) are directly affected by blue light irradiation in vitro. Here, we report that irradiation neither induced apoptosis nor maturation of monocyte-derived and myeloid DC. However, subsequent DC maturation upon LPS/IFNγ stimulation was impaired in a dose-dependent manner as assessed by maturation markers and cytokine release. Moreover, the potential of this DC to induce cytokine secretion from allogeneic CD4 T cells was reduced. In conclusion, unlike UV irradiation, blue light irradiation at high and low doses only resulted in impaired DC maturation upon activation and a reduced subsequent stimulatory capacity in allogeneic MLRs with strongest effects at higher doses. PMID:23879817

  17. Stable blue phosphorescent organic light emitting devices

    SciTech Connect

    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.

  18. Blue-green and green phosphors for lighting applications

    DOEpatents

    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.

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

    PubMed Central

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

    2012-01-01

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

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

    NASA Astrophysics Data System (ADS)

    Bergh, Arpad A.

    2004-09-01

    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.

  1. Response of THP-1 monocytes to blue light from dental curing lights.

    PubMed

    Wataha, J C; Lewis, J B; Lockwood, P E; Noda, M; Messer, R L; Hsu, S

    2008-02-01

    Blue light curing units (wavelengths of 400-500 nm) are a mainstay of restorative dentistry, and several high-intensity light sources have been developed to polymerize resin composites more rapidly. The biological safety of visible light has been assumed, but some reports of adverse biological effects of blue light in non-dental contexts support further evaluation of the biological safety of high-intensity blue light. The current study tested the hypothesis that blue light provokes cell stress responses resulting in the secretion of cytokines or expression of heat-shock proteins (HSP) in monocytes. Human monocytic cells were irradiated with three light sources (quartz-tungsten-halogen, plasma-arc and laser), then cellular proliferation, secretion of the inflammatory cytokine TNFalpha and induction of HSP72 were measured. Results indicated that although all three light sources significantly inhibited proliferation of monocytes, the secretion of TNFalpha was not induced following exposure to blue light and was not potentiated with administration of the activator lipopolysaccharide. Similarly, treatment with the plasma-arc light, which caused the largest temperature increase in previous studies, did not induce HSP72. The current results do not support activation of monocytes by blue light as an inflammatory risk factor in dental tissues during curing of composites. However, the results of the current study should be further verified in primary monocytes and an animal model before decisions about clinical risks are made. PMID:18197843

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

    PubMed

    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) p<0.001). Total protein concentration increased after irradiation with 3, 5 and 10J/cm(2), reaching statistical significance at 5J/cm(2) compared to control (p<0.0001). However, hydroxyproline levels did not differ between groups. Similarly, bFGF and IL-10 concentrations did not differ between groups, but IL-6 concentration decreased progressively as fluence increased (p<0.0001). Fluorescence analysis showed viable cells regardless of irradiation fluence. We conclude that irradiation with blue light at low fluence does not impair in vitro wound healing. The significant decrease in IL-6 suggests that 470nm light is anti-inflammatory. PMID:27092999

  3. A single blue nanorod light emitting diode.

    PubMed

    Hou, Y; Bai, J; Smith, R; Wang, T

    2016-05-20

    We report a light emitting diode (LED) consisting of a single InGaN/GaN nanorod fabricated by a cost-effective top-down approach from a standard LED wafer. The device demonstrates high performance with a reduced quantum confined Stark effect compared with a standard planar counterpart fabricated from the same wafer, confirmed by optical and electrical characterization. Current density as high as 5414 A cm(-2) is achieved without significant damage to the device due to the high internal quantum efficiency. The efficiency droop is mainly ascribed to Auger recombination, which was studied by an ABC model. Our work provides a potential method for fabricating compact light sources for advanced photonic integrated circuits without involving expensive or time-consuming fabrication facilities. PMID:27070200

  4. A single blue nanorod light emitting diode

    NASA Astrophysics Data System (ADS)

    Hou, Y.; Bai, J.; Smith, R.; Wang, T.

    2016-05-01

    We report a light emitting diode (LED) consisting of a single InGaN/GaN nanorod fabricated by a cost-effective top-down approach from a standard LED wafer. The device demonstrates high performance with a reduced quantum confined Stark effect compared with a standard planar counterpart fabricated from the same wafer, confirmed by optical and electrical characterization. Current density as high as 5414 A cm‑2 is achieved without significant damage to the device due to the high internal quantum efficiency. The efficiency droop is mainly ascribed to Auger recombination, which was studied by an ABC model. Our work provides a potential method for fabricating compact light sources for advanced photonic integrated circuits without involving expensive or time-consuming fabrication facilities.

  5. Blue light reduces organ injury from ischemia and reperfusion

    PubMed Central

    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. Thermally enhanced blue light-emitting diode

    NASA Astrophysics Data System (ADS)

    Xue, Jin; Zhao, Yuji; Oh, Sang-Ho; Herrington, William F.; Speck, James S.; DenBaars, Steven P.; Nakamura, Shuji; Ram, Rajeev J.

    2015-09-01

    We investigate thermoelectric pumping in wide-bandgap GaN based light-emitting diodes (LEDs) to take advantage of high junction temperature rather than avoiding the problem of temperature-induced efficiency droop through external cooling. We experimentally demonstrate a thermally enhanced 450 nm GaN LED, in which nearly fourfold light output power is achieved at 615 K (compared to 295 K room temperature operation), with nearly no reduction in the wall-plug efficiency (i.e., electrical-optical energy conversion efficiency) at bias V <ℏω/q . The LED is shown to work in a mode similar to a thermodynamic heat engine operating with charged carriers pumped into the active region by a combination of electrical work and Peltier heat (phonons) drawn from the lattice. In this optimal operating regime at 615 K, the LED injection current (3.26 A/cm2) is of similar magnitude to the operating point of common high power GaN based LEDs (5-35 A/cm2). This result suggests the possibility of removing bulky heat sinks in current high power LED products thus realizing a significant cost reduction for solid-state lighting.

  7. Capsule Design for Blue Light Therapy against Helicobacter pylori.

    PubMed

    Li, Zhangyong; Ren, Binbin; Tan, Haiyan; Liu, Shengrong; Wang, Wei; Pang, Yu; Lin, Jinzhao; Zeng, Chen

    2016-01-01

    A photo-medical capsule that emits blue light for Helicobacter pylori treatment was described in this paper. The system consists of modules for pH sensing and measuring, light-emitting diode driver circuit, radio communication and microcontroller, and power management. The system can differentiate locations by monitoring the pH values of the gastrointestinal tract, and turn on and off the blue light according to the preset range of pH values. Our experimental tests show that the capsule can operate in the effective light therapy mode for more than 32 minutes and the wireless communication module can reliably transmit the measured pH value to a receiver located outside the body. PMID:26814481

  8. Capsule Design for Blue Light Therapy against Helicobacter pylori

    PubMed Central

    Tan, Haiyan; Liu, Shengrong; Wang, Wei; Pang, Yu; Lin, Jinzhao; Zeng, Chen

    2016-01-01

    A photo-medical capsule that emits blue light for Helicobacter pylori treatment was described in this paper. The system consists of modules for pH sensing and measuring, light-emitting diode driver circuit, radio communication and microcontroller, and power management. The system can differentiate locations by monitoring the pH values of the gastrointestinal tract, and turn on and off the blue light according to the preset range of pH values. Our experimental tests show that the capsule can operate in the effective light therapy mode for more than 32 minutes and the wireless communication module can reliably transmit the measured pH value to a receiver located outside the body. PMID:26814481

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

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

    NASA Technical Reports Server (NTRS)

    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.

  11. Blue and white light emission from zinc oxide nanoforests

    PubMed Central

    Capuano, Thomas; Manthina, Venkata; Agrios, Alexander G; Silva, Helena; Gokirmak, Ali

    2015-01-01

    Summary 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. PMID:26885458

  12. Blue and white light emission from zinc oxide nanoforests.

    PubMed

    Noor, Nafisa; Lucera, Luca; Capuano, Thomas; Manthina, Venkata; Agrios, Alexander G; Silva, Helena; Gokirmak, Ali

    2015-01-01

    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. PMID:26885458

  13. Extending MODIS Deep Blue Aerosol Retrieval Coverage to Cases of Absorbing Aerosols Above Clouds: First Results

    NASA Technical Reports Server (NTRS)

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

    2015-01-01

    Absorbing smoke or mineral dust aerosols above clouds (AAC) are a frequent occurrence in certain regions and seasons. Operational aerosol retrievals from sensors like MODIS omit AAC because they are designed to work only over cloud-free scenes. However, AAC can in principle be quantified by these sensors in some situations (e.g. Jethva et al., 2013; Meyer et al., 2013). We present a summary of some analyses of the potential of MODIS-like instruments for this purpose, along with two case studies using airborne observations from the Ames Airborne Tracking Sunphotometer (AATS; http://geo.arc.nasa.gov/sgg/AATS-website/) as a validation data source for a preliminary AAC algorithm applied to MODIS measurements. AAC retrievals will eventually be added to the MODIS Deep Blue (Hsu et al., 2013) processing chain.

  14. Source apportionment of light absorbing WSOC in South Asian outflow

    NASA Astrophysics Data System (ADS)

    Bosch, Carme; Kirillova, Elena; Andersson, August; Kruså, Martin; Budhavant, Krishnakant; Tiwari, Suresh; Gustafsson, Örjan

    2013-04-01

    Carbonaceous aerosols (CA) formed over South Asia are of special concern for human health and regional climate impacts. Anthropogenic emissions forming CA are generally high throughout the region and particularly over the Indo-Gangetic Plain. The net effects of CA on radiative climate forcing are still uncertain. One of the components of CA is black carbon (BC), dominated by soot-like elemental carbon, a strong absorber of solar radiation. Another component is organic carbon (OC), traditionally considered as a light scattering particle. However, recent field studies have shown OC to absorb at lower wavelengths. Thus OC, in addition to BC, may also contribute to light absorption and have a positive direct radiative effect on climate. Light absorbing organic aerosol is usually termed brown carbon (BrC). A significant fraction of BrC is water-soluble, therefore its dissolution into clouds could result in absorbing droplets that affect the cloud absorption and thus contributing to the indirect aerosol climate effects. In this study, light absorption and δ13C + Δ14C isotopic measurements of WSOC were studied in fine aerosols (PM 2.5) at two sites during early pre-monsoon season. New Delhi, one of the most densely populated and industrialized urban megacities in South Asia, was chosen to represent a strong source and Maldives Climate Observatory at Hanimaadhoo (MCOH) was chosen as a regional receptor which in wintertime is located downwind of the Indian subcontinent. Sampling in Delhi was done from mid-February to mid-March 2011 and in MCOH during March 2012. WSOC concentrations were 12±4.5 and 0.71±0.30 μg m-3 in Delhi and MCOH respectively. Whereas in Delhi WSOC contributed 31±4% of total organic carbon, this contribution was slightly higher in MCOH (40±12%). Light absorption by WSOC exhibited strong wavelength (?) dependence. In Maldives, WSOC Absorption Ångström Exponent (AAE) was found to be 6.9±0.4 and Mass Absorption Efficiency (MAE) measured at 365 nm

  15. Alterations in enamel remineralization in vitro induced by blue light

    NASA Astrophysics Data System (ADS)

    Kato, I. T.; Zezell, D. M.; Mendes, F. M.; Wetter, N. U.

    2010-06-01

    Blue light, especially from LED devices, is a very frequently used tool in dental procedures. However, the investigations of its effects on dental enamel are focused primarily on enamel demineralization and fluoride retention. Despite the fact that this spectral region can inhibit enamel demineralization, the effects of the irradiation on demineralized enamel are not known. For this reason, we evaluated the effects of blue LED on remineralization of dental enamel. Artificial lesions were formed in bovine dental enamel blocks by immersing the samples in undersaturated acetate buffer. The lesions were irradiated with blue LED (455 nm, 1.38 W/cm2, 13.75 J/cm2, and 10 s) and remineralization was induced by pH-cycling process. Cross-sectional hardness was used to asses mineral changes after remineralization. Non-irradiated enamel lesions presented higher mineral content than irradiated ones. Furthermore, the mineral content of irradiated group was not significantly different from the lesion samples that were not submitted to the remineralization process. Results obtained in the present study show that the blue light is not innocuous for the dental enamel and inhibition of its remineralization can occur.

  16. Selective Cell Targeting with Light-Absorbing Microparticles and Nanoparticles

    PubMed Central

    Pitsillides, Costas M.; Joe, Edwin K.; Wei, Xunbin; Anderson, R. Rox; Lin, Charles P.

    2003-01-01

    We describe a new method for selective cell targeting based on the use of light-absorbing microparticles and nanoparticles that are heated by short laser pulses to create highly localized cell damage. The method is closely related to chromophore-assisted laser inactivation and photodynamic therapy, but is driven solely by light absorption, without the need for photochemical intermediates (particularly singlet oxygen). The mechanism of light-particle interaction was investigated by nanosecond time-resolved microscopy and by thermal modeling. The extent of light-induced damage was investigated by cell lethality, by cell membrane permeability, and by protein inactivation. Strong particle size dependence was found for these interactions. A technique based on light to target endogenous particles is already being exploited to treat pigmented cells in dermatology and ophthalmology. With exogenous particles, phamacokinetics and biodistribution studies are needed before the method can be evaluated against photodynamic therapy for cancer treatment. However, particles are unique, unlike photosensitizers, in that they can remain stable and inert in cells for extended periods. Thus they may be particularly useful for prelabeling cells in engineered tissue before implantation. Subsequent irradiation with laser pulses will allow control of the implanted cells (inactivation or modulation) in a noninvasive manner. PMID:12770906

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

    PubMed

    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. PMID:26768920

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

    PubMed Central

    Hogewoning, Sander W.; Trouwborst, Govert; Maljaars, Hans; Poorter, Hendrik; van Ieperen, Wim; Harbinson, Jeremy

    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 equal irradiance under seven different combinations of red and blue light provided by light-emitting diodes. Only the leaves developed under red light alone (0% blue) displayed dysfunctional photosynthetic operation, characterized by a suboptimal and heterogeneously distributed dark-adapted Fv/Fm, a stomatal conductance unresponsive to irradiance, and a relatively low light-limited quantum yield for CO2 fixation. Only 7% blue light was sufficient to prevent any overt dysfunctional photosynthesis, which can be considered a qualitatively blue light effect. The photosynthetic capacity (Amax) was twice as high for leaves grown at 7% blue compared with 0% blue, and continued to increase with increasing blue percentage during growth measured up to 50% blue. At 100% blue, Amax was lower but photosynthetic functioning was normal. The increase in Amax with blue percentage (0–50%) was associated with an increase in leaf mass per unit leaf area (LMA), nitrogen (N) content per area, chlorophyll (Chl) content per area, and stomatal conductance. Above 15% blue, the parameters Amax, LMA, Chl content, photosynthetic N use efficiency, and the Chl:N ratio had a comparable relationship as reported for leaf responses to irradiance intensity. It is concluded that blue light during growth is qualitatively required for normal photosynthetic functioning and quantitatively mediates leaf responses resembling those to irradiance intensity. PMID:20504875

  19. Photoluminescence mechanism for blue-light-emitting porous silicon

    NASA Astrophysics Data System (ADS)

    Qin, G. G.; Liu, X. S.; Ma, S. Y.; Lin, J.; Yao, G. Q.; Lin, X. Y.; Lin, K. X.

    1997-05-01

    A comparative study of photoluminescence (PL) and photoluminescence excitation (PLE) spectra of porous silicon (PS) and Si oxide, both emitting blue light, is reported. The PLE spectrum of Si oxide monitored at 460 nm displays a three-peak structure with peak wavelengths around 265, 300, and 360 nm. The PLE intensity of the PS sample increases with decreasing excitation wavelength, and has three shoulders located at wavelengths near the three PLE peak wavelengths of Si oxide. When the PS sample is oxidized for half an hour at 1150 °C [the temperature at which nanometer Si particles (NSP's) inside PS disappear], blue-light PL intensity reduces greatly, and its PLE spectrum changes into a spectrum very similar to that of Si oxide. The experimental result strongly indicates that for the blue-light emission from PS there are two types of photoexcitation processes: photoexcitation occurs in NSP"s and in the Si oxide layers covering NSP's, and radiative recombination of electron-hole pairs is carried out in luminescence centers located on the interfaces between NSP"s and Si oxide and in those inside Si oxide layers.

  20. Blue-green phosphor for fluorescent lighting applications

    DOEpatents

    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 Regulation of Cell Division in Chlamydomonas reinhardtii 1

    PubMed Central

    Münzner, Petra; Voigt, Jürgen

    1992-01-01

    A delay in cell division was observed when synchronized cultures of the unicellular green alga Chlamydomonas reinhardtii growing under heterotrophic conditions were exposed to white light during the second half of the growth period. This effect was also observed when photosynthesis was blocked by addition of the photosystem II inhibitor 3-(3,4-dichlorophenyl)-1,1-dimethylurea. Light pulses of 10 minutes were sufficient to induce a delay in cell division in the presence or absence of 3-(3,4-dichlorophenyl)-1,1-dimethylurea. A delay in cell division was induced by blue light but not by illumination with red or far-red light. The equal intensity action spectrum revealed two peaks at 400 and 500 nm. PMID:16669046

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

    PubMed Central

    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

  3. Blue light generation using periodically poled nonlinear crystals

    NASA Astrophysics Data System (ADS)

    Khademian, Ali; Shiner, David

    2013-05-01

    We have studied blue light generation using SHG of IR light. We have used single pass waveguides and bulk crystals with buildup cavities. The nonlinear crystals used were periodically poled Lithium Niobate (LN) and Potassium Titanyl Phosphate (KTP). Each of these approaches had limitations with regards to the maximum power handling and the stability of operation. Currently we are working on a different crystal in a new buildup cavity to circumvent some of the previous difficulties resulting from photorefractive damage and excessive heating due to blue absorption. Our initial measurements show that Lithium Tantalite (LT) has higher photorefractive threshold and much lower blue absorption (2% vs 15% for 20 mm crystal length). The new buildup cavity incorporates a more convenient commercial piezo mirror translator for feedback control. The buildup cavity can be operated with a minimum of 6 V as opposed to the 1000 V previously. We are exploring the use of a single DSP (digital signal processor) to perform all the locking and electronic control functions of the cavity. We are studying the coupling and propagation properties of the IR beams more carefully to minimize cavity and coupling losses, particularly due to front wave distortion caused by mirrors and lenses used in the setup. To optimize our cavity and to make the best and simplest choice of optical elements possible, different commercial (off the shelf) lenses and mirrors have been evaluated experimentally in our setup. This work is supported by NSF grant PHY-1068868.

  4. Synthesis of quinoline based heterocyclic compounds for blue lighting application

    NASA Astrophysics Data System (ADS)

    Kumar, Vinod; Gohain, Mukut; Van Tonder, Johannes H.; Ponra, S.; Bezuindenhoudt, B. C. B.; Ntwaeaborwa, O. M.; Swart, H. C.

    2015-12-01

    2,4-Diphenylquinoline (DPQ), derivatives 6-chloro-2,4-diphenylquinoline (DPQ-Cl) and 4‧,6-dichloro-2,4-diphenylquinoline (DPQ-Cl2) were synthesized using a three-component domino reaction. The DPQ, DPQ-Cl and DPQ-Cl2 were characterized by nuclear magnetic resonance spectroscopy, scanning electron microscopy, thermogravimetric analysis (TGA). Fourier transformed infra-red spectroscopy, X-ray photoelectron spectroscopy (XPS), Ultraviolet-visible (UV-vis) spectroscopy and photoluminescence spectroscopy. The TGA results showed that the DPQ was more thermally stable with respect to the DPQ-Cl and DPQ-Cl2. The synthesized organic phosphors showed bright emission in the blue region under an UV excitation wavelength of 325 nm with the power of 18 mW. These organic phosphors were found to be efficient candidate and may be used in organic blue light emitting devices.

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

    PubMed Central

    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

  6. Exploring Light's Interactions with Bubbles and Light Absorbers in Photoelectrochemical Devices using Ray Tracing

    SciTech Connect

    Stevens, John

    2013-12-01

    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 SrTiO! 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.

  7. The green-absorbing Drosophila Rh6 visual pigment contains a blue-shifting amino acid substitution that is conserved in vertebrates.

    PubMed

    Salcedo, Ernesto; Farrell, David M; Zheng, Lijun; Phistry, Meridee; Bagg, Eve E; Britt, Steven G

    2009-02-27

    The molecular mechanisms that regulate invertebrate visual pigment absorption are poorly understood. Through sequence analysis and functional investigation of vertebrate visual pigments, numerous amino acid substitutions important for this adaptive process have been identified. Here we describe a serine/alanine (S/A) substitution in long wavelength-absorbing Drosophila visual pigments that occurs at a site corresponding to Ala-292 in bovine rhodopsin. This S/A substitution accounts for a 10-17-nm absorption shift in visual pigments of this class. Additionally, we demonstrate that substitution of a cysteine at the same site, as occurs in the blue-absorbing Rh5 pigment, accounts for a 4-nm shift. Substitutions at this site are the first spectrally significant amino acid changes to be identified for invertebrate pigments sensitive to visible light and are the first evidence of a conserved tuning mechanism in vertebrate and invertebrate pigments of this class. PMID:19126545

  8. Low voltage blue phase liquid crystal for spatial light modulators.

    PubMed

    Peng, Fenglin; Lee, Yun-Han; Luo, Zhenyue; Wu, Shin-Tson

    2015-11-01

    We demonstrated a low-voltage polymer-stabilized blue phase liquid crystal (BPLC) for phase-only modulation with a liquid-crystal-on-silicon (LCoS). A new device configuration was developed, which allows the incident laser beam to traverse the BPLC layer four times before exiting the LCoS. As a result, the 2π phase change voltage is reduced to below 24 V in the visible region. The response time remains relatively fast (∼3  ms). The proposed device configuration enables widespread applications of BPLC spatial light modulators. PMID:26512528

  9. Photochemical aging of light-absorbing secondary organic aerosol material.

    PubMed

    Sareen, Neha; Moussa, Samar G; McNeill, V Faye

    2013-04-11

    Dark reactions of methylglyoxal with NH4(+) in aqueous aerosols yield light-absorbing and surface-active products that can influence the physical properties of the particles. Little is known about how the product mixture and its optical properties will change due to photolysis as well as oxidative aging by O3 and OH in the atmosphere. Here, we report the results of kinetics and product studies of the photochemical aging of aerosols formed by atomizing aqueous solutions of methylglyoxal and ammonium sulfate. Experiments were performed using aerosol flow tube reactors coupled with an aerosol chemical ionization mass spectrometer (Aerosol-CIMS) for monitoring gas- and particle-phase compositions. Particles were also impacted onto quartz windows in order to assess changes in their UV-visible absorption upon oxidation. Photooxidation of the aerosols leads to the formation of small, volatile organic acids including formic acid, acetic acid, and glyoxylic acid. The atmospheric lifetime of these species during the daytime is predicted to be on the order of minutes, with photolysis being an important mechanism of degradation. The lifetime with respect to O3 oxidation was observed to be on the order of hours. O3 oxidation also leads to a net increase in light absorption by the particles due to the formation of additional carbonyl compounds. Our results are consistent with field observations of high brown carbon absorption in the early morning. PMID:23506538

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

    ERIC Educational Resources Information Center

    Smith, Rachel; Cantrell, Kevin

    2007-01-01

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

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

    PubMed Central

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

    2016-01-01

    Purpose To investigate the influence of overexposure to light emitting diode (LED)-derived light with various wavelengths on mouse ocular surface. Methods 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. Results 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. Conclusions 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. PMID:27517861

  12. Antimicrobial blue light therapy for Candida albicans burn infection in mice

    NASA Astrophysics Data System (ADS)

    Zhang, Yunsong; Wang, Yucheng; Murray, Clinton K.; Hamblin, Michael R.; Gu, Ying; Dai, Tianhong

    2015-05-01

    In this preclinical study, we investigated the utility of antimicrobial blue light therapy for Candida albicans infection in acutely burned mice. A bioluminescent strain of C. albicans was used. The susceptibilities to blue light inactivation were compared between C. albicans and human keratinocyte. In vitro serial passaging of C. albicans on blue light exposure was performed to evaluate the potential development of resistance to blue light inactivation. A mouse model of acute thermal burn injury infected with the bioluminescent strain of C. albicans was developed. Blue light (415 nm) was delivered to mouse burns for decolonization of C. albicans. Bioluminescence imaging was used to monitor in real time the extent of fungal infection in mouse burns. Experimental results showed that C. albicans was approximately 42-fold more susceptible to blue light inactivation in vitro than human keratinocyte (P=0.0022). Serial passaging of C. albicans on blue light exposure implied a tendency for the fungal susceptibility to blue light inactivation to decrease with the numbers of passages. Blue light reduced fungal burden by over 4-log10 (99.99%) in acute mouse burns infected with C. albicans in comparison to infected mouse burns without blue light therapy (P=0.015).

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

    PubMed

    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. PMID:25545446

  14. Blue light- and genetically-reversed gravitropic response in protonemata of the moss Ceratodon purpureus.

    PubMed

    Lamparter, T; Hughes, J; Hartmann, E

    1998-09-01

    In darkness, protonemal filaments of Ceratodon purpureus (Brid.) grow negatively gravitropically (upwards). Red light induces a positive phototropic response mediated by the photoreceptor phytochrome. A red light treatment also has an inhibitory effect on the gravitropic response, an effect also mediated by phytochrome. In this study the effects of blue light on phototropism and on gravitropism were analysed. Unilateral blue light resulted in only a weak phototropic response, but markedly randomised growth direction. Blue light given together with a gravitropic stimulus reversed the gravitropism, changing it from negative to positive (filaments grow downward). The effect of blue light was also analysed with the mutant ptr116, which is defective in the biosynthesis of the phytochrome chromophore, and in a newly isolated mutant wwr2, which is positively gravitropic in darkness. Blue light induced the same reversal of gravitropism in ptrll6 as in the wild type, indicating that phytochrome is not involved in this process. In wwr2 the direction of gravitropism was unaltered by the blue light treatment. Light also affects chlorophyll content and the size of plastids, potential statoliths for gravitropism. Red light induced an increase in plastid size and chlorophyll content in the wild type but not in ptr116. Blue light induced a similar change in wild type plastids. It seems as though light-induced alterations of gravitropism are not simply mediated by alterations in plastid properties, and that red light and blue light evoke fundamentally different responses. PMID:11536885

  15. Nanofocusing of longitudinally polarized light using absorbance modulation

    SciTech Connect

    Li, Qiang; Zhao, Xing Zhang, Bo; Zheng, Yi; Zhou, Liqiu; Fang, Zhiliang; Wang, Lingjie; Wu, Yanxiong

    2014-02-10

    Recently, many methods based on amplitude or phase modulation to reduce the focal spot and enhance the longitudinal field component of a tight-focused radially polarized light beam have been suggested. But they all suffer from spot size limit 0.36λ/NA and large side lobes strength in longitudinal component. Here, we report a method of generating a tighter focused spot by focusing radially polarized and azimuthally polarized beams of different wavelengths on a thin photochromic film through a high-numerical-aperture lens simultaneously. In this method, by suppressing the radial component and compressing the longitudinal component of radially polarized beam, absorbance modulation makes the ultimate spot size break the size limit of 0.36λ/NA with side-lobe intensity of longitudinal component below 1% of central-peak intensity. The theoretical analysis and simulation demonstrate that the focal spot size could be smaller than 0.1λ with nearly all radial component blocked at high intensity ratio of the two illuminating beams.

  16. Comparison of transcriptome under red and blue light culture of Saccharina japonica (Phaeophyceae).

    PubMed

    Wang, Wen-Jun; Wang, Fei-Jiu; Sun, Xiu-Tao; Liu, Fu-Li; Liang, Zhou-Rui

    2013-04-01

    Saccharina japonica is one of the most important economic seaweeds. Several aspects such as photosynthesis in Saccharina lives are affected by blue light, the predominant light spectrum in the habitat. In this study, transcriptome profiling of S. japonica by next generation sequencing technology generated 55,102 qualified transcripts and 40.5 % transcripts were assigned to functional annotation. Expression of a large proportion of genes has been previously reported to be regulated by blue light, taking dark as control. However, by comparison among white, blue and red light, the significantly differentially expressed gene tags (DEGs) accounted for only 6.75 % of the identified sequences. It indicated that light-regulated gene expression in kelps is not a specific blue-light response. Unexpectedly, red light had more extensive effects on the transcriptomic activity than blue light did, since the most (68.4 %) DEGs were red light-regulated and only 17.5 % were specifically regulated by blue light. Some of the DEGs with the highest mRNA levels under blue light are not blue light-upregulated but red light-downregulated. The extensive regulation on gene expression under red light together with the abundant presence of phytochrome-like protein gene tags in S. japonica indicated their significant roles in the lives of brown algae. By highlighting the photosynthetic metabolism, blue light is more efficient than red light in triggering the pigment biosynthesis, light reaction and carbon fixation, revealing a molecular basis for rapid growth of kelps, since most of the time blue light is predominant in their habitat. PMID:23277166

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

    PubMed Central

    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

  18. Red and blue pulse timing control for pulse width modulation light dimming of light emitting diodes for plant cultivation.

    PubMed

    Shimada, Aoi; Taniguchi, Yoshio

    2011-09-01

    A pulse width modulation (PWM) light dimming system containing red and blue light emitting diodes was designed and constructed. Cultivation of the plant Arabidopsis thaliana under various light dimming wave patterns was compared. Control of the pulse timing (phase of wave pattern) between red and blue light in PWM light dimming was examined. Different plant growth was obtained by changing the phase of red and blue pulses. Pulse timing control of PWM light dimming for plant cultivation has the potential to act as a method for probing photosynthesis. PMID:21622005

  19. Chlorine-free pyrotechnics: copper(I) iodide as a "green" blue-light emitter.

    PubMed

    Klapötke, Thomas M; Rusan, Magdalena; Sabatini, Jesse J

    2014-09-01

    The generation of blue-light-emitting pyrotechnic formulations without the use of chlorine-containing compounds is reported. Suitable blue-light emission has been achieved through the generation of molecular emitting copper(I) iodide. The most optimal copper(I) iodide based blue-light-emitting formulation was found to have performances exceeding those of chlorine-containing compositions, and was found to be insensitive to various ignition stimuli. PMID:25044436

  20. Stabilizing blue phase liquid crystals with linearly polarized UV light

    NASA Astrophysics Data System (ADS)

    Xu, Daming; Yuan, Jiamin; Schadt, Martin; Yan, Jing; Wu, Shin-Tson

    2015-03-01

    Polymer-stabilized blue-phase liquid crystal (PS-BPLC) has become an increasingly important technology trend for information display and photonic applications. BPLC exhibits several attractive features, such as reasonably wide temperature range, submillisecond gray-to-gray response time, no need for alignment layer, optically isotropic voltageoff state, and large cell gap tolerance when an in-plane switching (IPS) cell is employed. However, some bottlenecks such as high operation voltage, relatively low transmittance, and noticeable hysteresis and prolonged response time at high field region for IPS mode, still remain to be overcome before widespread application of BPLC can be realized. To reduce operation voltage, both new BPLC materials and new device structures have been investigated. In this paper, we demonstrate the stabilization a photopolymer-embedded blue phase liquid crystal precursor using a linearly polarized UV light for first time. When the UV polarization axis is perpendicular to the stripe electrodes of an IPS cell, anisotropic polymer networks are formed through the linear photo-polymerization process and the electrostriction effect is suppressed. As a result, the measured hysteresis is dramatically reduced from 6.95% to 0.36% and the response time shortened by ~2X compared to unpolarized UV exposure. To induce larger anisotropy in polymer networks for mitigating the electrostriction effect, high-intensity linearly polarized UV exposure is preferred. It is foreseeable this method will guide future BPLC device and material development as well as manufacturing process. The dawn of BPLCD is near.

  1. Soybean stem growth under high-pressure sodium with supplemental blue lighting

    NASA Technical Reports Server (NTRS)

    Wheeler, R. M.; Mackowiak, C. L.; Sager, J. C.

    1991-01-01

    To study high-pressure sodium (HPS) lamps used for plant lighting because of their high energy conversion efficiencies, 'McCall' soybean plants were grown for 28 days in growth chambers utilizing HPS lamps, with/without supplemental light from blue phosphor fluorescent lamps. Total photosynthetic photon flux levels, including blue fluorescent, were maintained near 300 or 500 micromol/sq m s. Results indicate that employment of HPS or other blue-deficient sources for lighting at low to moderate photosynthetic photon flux levels may cause abnormal stem elongation, but this can be prevented by the addition of a small amount of supplemental blue light.

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

    SciTech Connect

    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

    2012-10-15

    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{sup 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.

  3. Stomatal Blue Light Response Is Present in Early Vascular Plants.

    PubMed

    Doi, Michio; Kitagawa, Yuki; Shimazaki, Ken-ichiro

    2015-10-01

    Light is a major environmental factor required for stomatal opening. Blue light (BL) induces stomatal opening in higher plants as a signal under the photosynthetic active radiation. The stomatal BL response is not present in the fern species of Polypodiopsida. The acquisition of a stomatal BL response might provide competitive advantages in both the uptake of CO2 and prevention of water loss with the ability to rapidly open and close stomata. We surveyed the stomatal opening in response to strong red light (RL) and weak BL under the RL with gas exchange technique in a diverse selection of plant species from euphyllophytes, including spermatophytes and monilophytes, to lycophytes. We showed the presence of RL-induced stomatal opening in most of these species and found that the BL responses operated in all euphyllophytes except Polypodiopsida. We also confirmed that the stomatal opening in lycophytes, the early vascular plants, is driven by plasma membrane proton-translocating adenosine triphosphatase and K(+) accumulation in guard cells, which is the same mechanism operating in stomata of angiosperms. These results suggest that the early vascular plants respond to both RL and BL and actively regulate stomatal aperture. We also found three plant species that absolutely require BL for both stomatal opening and photosynthetic CO2 fixation, including a gymnosperm, C. revoluta, and the ferns Equisetum hyemale and Psilotum nudum. PMID:26307440

  4. Phosphatidic acid inhibits blue light-induced stomatal opening via inhibition of protein phosphatase 1 [corrected].

    PubMed

    Takemiya, Atsushi; Shimazaki, Ken-ichiro

    2010-08-01

    Stomata open in response to blue light under a background of red light. The plant hormone abscisic acid (ABA) inhibits blue light-dependent stomatal opening, an effect essential for promoting stomatal closure in the daytime to prevent water loss. However, the mechanisms and molecular targets of this inhibition in the blue light signaling pathway remain unknown. Here, we report that phosphatidic acid (PA), a phospholipid second messenger produced by ABA in guard cells, inhibits protein phosphatase 1 (PP1), a positive regulator of blue light signaling, and PA plays a role in stimulating stomatal closure in Vicia faba. Biochemical analysis revealed that PA directly inhibited the phosphatase activity of the catalytic subunit of V. faba PP1 (PP1c) in vitro. PA inhibited blue light-dependent stomatal opening but did not affect red light- or fusicoccin-induced stomatal opening. PA also inhibited blue light-dependent H(+) pumping and phosphorylation of the plasma membrane H(+)-ATPase. However, PA did not inhibit the autophosphorylation of phototropins, blue light receptors for stomatal opening. Furthermore, 1-butanol, a selective inhibitor of phospholipase D, which produces PA via hydrolysis of phospholipids, diminished the ABA-induced inhibition of blue light-dependent stomatal opening and H(+) pumping. We also show that hydrogen peroxide and nitric oxide, which are intermediates in ABA signaling, inhibited the blue light responses of stomata and that 1-butanol diminished these inhibitions. From these results, we conclude that PA inhibits blue light signaling in guard cells by PP1c inhibition, accelerating stomatal closure, and that PP1 is a cross talk point between blue light and ABA signaling pathways in guard cells. PMID:20498335

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

    NASA Astrophysics Data System (ADS)

    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 (P<0.001). Maximum eradication of the US-300 (92.1%) and the IS-853 colonies (93.5%) was achieved within 10 minutes of irradiation with each wavelength. The longer the irradiation the more bacteria were eradicated. However, the effect 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.

  6. Vanadate Inhibits Blue Light-Stimulated Swelling of Vicia Guard Cell Protoplasts 1

    PubMed Central

    Amodeo, Gabriela; Srivastava, Alaka; Zeiger, Eduardo

    1992-01-01

    When supplied under low chloride concentrations, vanadate inhibits the blue light-stimulated swelling of Vicia faba L. guard cell protoplasts in a dose-dependent fashion. The volume of guard cell protoplasts incubated in 10 mm K-imino-diacetic acid, 0.4 m mannitol, and 1 mm CaCl2 remained essentially constant under 1000 μmol m−2 s−1 red light, but increased an average of 27% after 8 min of the addition of 50 μmol m−2 s−1 blue light to the background red light. At 500 μm, vanadate completely inhibits the response to blue light. Vanadate also inhibits the swelling of guard cell protoplasts stimulated by the H+-ATPase agonist fusicoccin. The vanadate sensitivity of the blue light-stimulated swelling implicates a proton-pumping ATPase as a component of the sensory transduction of blue light in guard cells. Images Figure 3 PMID:16653159

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

    PubMed

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

    2016-02-19

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

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

    PubMed Central

    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

  9. Enabling a blue-hazard free general lighting based on candle light-style OLED.

    PubMed

    Jou, Jwo-Huei; Kumar, Sudhir; An, Chih-Chia; Singh, Meenu; Yu, Huei-Huan; Hsieh, Chun-Yu; Lin, You-Xing; Sung, Chao-Feng; Wang, Ching-Wu

    2015-06-01

    Increasing studies report blue light to possess a potential hazard to the retina of human eyes, secretion of melatonin and artworks. To devise a human- and artwork-friendly light source and to also trigger a "Lighting Renaissance", we demonstrate here how to enable a quality, blue-hazard free general lighting source on the basis of low color-temperature organic light emitting diodes. With the use of multiple candlelight complementary emitters, the sensationally warm candle light-style emission is proven to be also drivable by electricity. To be energy-saving, highly efficient candle-light emission is demanded. The device shows, at 100 cd m-2 for example, an efficacy of 85.4 lm W-1, an external quantum efficiency of 27.4%, with a 79 spectrum resemblance index and 2,279 K color temperature. The high efficiency may be attributed to the candlelight emitting dyes with a high quantum yield, and the host molecules facilitating an effective host-to-guest energy transfer, as well as effective carrier injection balance. PMID:26072882

  10. 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

    NASA Astrophysics Data System (ADS)

    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.

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

    NASA Astrophysics Data System (ADS)

    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.

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

    PubMed

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

    2015-01-01

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

  13. White luminescence from CdS nanocrystals under the blue light excitation

    SciTech Connect

    Li, Bo; Zhang, Xiaosong Li, Lan; Li, Mengzhen; Xu, Jianping; Hong, Yuan

    2014-06-01

    Trap-rich CdS nanocrystals were synthesized by employing CdSt{sub 2} and sulfur as precursors via thermal decomposition. Furthermore, X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), absorption and photoluminescence (PL) spectra were used to characterize structure, morphology and luminescence properties of CdS nanocrystals (NCs). CdS NCs have a broad emission across 500–700 nm under the excitation of blue light with 460 nm, consequently, white light can be produced by mixing broad emission from CdS NCs excited by blue light, with the remaining blue light. In addition, the broad emission generation is closely and inseparably related to surface defects. Moreover, LaMer model was used to explain the phenomenon that the intensity of the trap emission gradually decreases as the reaction time increases in contrast with that of the band-edge emission. - Graphical abstract: Trap-rich CdS nanocrystals were synthesized. Furthermore, white light is produced by mixing broad emission across 500–700 nm from CdS NCs excited by blue light, in combination with the remaining blue light. - Highlights: • Trap-rich CdS nanocrystals were synthesized. • CdS NCs have a broad emission across 500–700 nm under the excitation of blue light. • White light can be produced by mixing broad emission with the remaining blue light.

  14. Effect of blue light radiation on curcumin-induced cell death of breast cancer cells

    NASA Astrophysics Data System (ADS)

    Zeng, X. B.; Leung, A. W. N.; Xia, X. S.; Yu, H. P.; Bai, D. Q.; Xiang, J. Y.; Jiang, Y.; Xu, C. S.

    2010-06-01

    In the present study, we have successfully set up a novel blue light source with the power density of 9 mW/cm2 and the wavelength of 435.8 nm and then the novel light source was used to investigate the effect of light radiation on curcumin-induced cell death. The cytotoxicity was investigated 24 h after the treatment of curcumin and blue light radiation together using MTT reduction assay. Nuclear chromatin was observed using a fluorescent microscopy with Hoechst33258 staining. The results showed blue light radiation could significantly enhance the cytotoxicity of curcumin on the MCF-7 cells and apoptosis induction. These findings demonstrated that blue light radiation could enhance curcumin-induced cell death of breast cancer cells, suggesting light radiation may be an efficient enhancer of curcumin in the management of breast cancer.

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

    PubMed

    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/cm(2)). 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

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

    PubMed Central

    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

  17. Penetration of UV-A, UV-B, blue, and red light into leaf tissues of pecan measured by a fiber optic microprobe system

    NASA Astrophysics Data System (ADS)

    Qi, Yadong; Bai, Shuju; Vogelmann, Thomas C.; Heisler, Gordon M.

    2003-11-01

    The depth of light penetration from the adaxial surfaces of the mature leaves of pecan (Carya illinoensis) was measured using a fiber optic microprobe system at four wavelengths: UV-B (310nm), UV-A (360 nm), blue light (430nm), and red light (680nm). The average thickness of the leaf adaxial epidermal layer was 15um and the total leaf thickness was 219um. The patterns of the light attenuation by the leaf tissues exhibited strong wavelength dependence. The leaf adaxial epidermal layer was chiefly responsible for absorbing the UV-A UV-B radiation. About 98% of 310 nm light was steeply attenuated within the first 5 um of the adaxial epidermis; thus, very little UV-B radiation was transmitted to the mesophyll tissues where contain photosynthetically sensitive sites. The adaxial epidermis also attenuated 96% of the UV-A radiation. In contrast, the blue and red light penetrated much deeper and was gradually attenutated by the leaves. The mesophyll tissues attenuated 17% of the blue light and 42% of the red light, which were available for photosynthesis use. Since the epidermal layer absorbed nearly all UV-B light, it acted as an effective filter screening out the harmful radiation and protecting photosynthetically sensitive tissues from the UV-B damage. Therefore, the epidermal function of the UV-B screening effectiveness can be regarded as one of the UV-B protection mechanisms in pecan.

  18. Blue-light-regulated transcription factor, Aureochrome, in photosynthetic stramenopiles.

    PubMed

    Takahashi, Fumio

    2016-03-01

    During the course of evolution through various endosymbiotic processes, diverse photosynthetic eukaryotes acquired blue light (BL) responses that do not use photosynthetic pathways. Photosynthetic stramenopiles, which have red algae-derived chloroplasts through secondary symbiosis, are principal primary producers in aquatic environments, and play important roles in ecosystems and aquaculture. Through secondary symbiosis, these taxa acquired BL responses, such as phototropism, chloroplast photo-relocation movement, and photomorphogenesis similar to those which green plants acquired through primary symbiosis. Photosynthetic stramenopile BL receptors were undefined until the discovery in 2007, of a new type of BL receptor, the aureochrome (AUREO), from the photosynthetic stramenopile alga, Vaucheria. AUREO has a bZIP domain and a LOV domain, and thus BL-responsive transcription factor. AUREO orthologs are only conserved in photosynthetic stramenopiles, such as brown algae, diatoms, and red tide algae. Here, a brief review is presented of the role of AUREOs as photoreceptors for these diverse BL responses and their biochemical properties in photosynthetic stramenopiles. PMID:26781435

  19. The effect of a green and blue monochromatic light combination on broiler growth and development.

    PubMed

    Rozenboim, I; Biran, I; Chaiseha, Y; Yahav, S; Rosenstrauch, A; Sklan, D; Halevy, O

    2004-05-01

    Previous reports have suggested that green light enhances broiler growth at an early age, whereas blue light enhances growth at older ages. The aim of this study was to examine the effect of a switch in monochromatic light at 2 ages on growth and development of broilers. Male chicks (Anak, n = 640) were used. After hatch, chicks were weighed, wing-banded, and blocked into treatment groups. Chicks were grown in 1-m2 pens in 8 isolated light-proof rooms (20 birds/pen). The light treatments were (1) Control white (mini-incandescent lamps), 2) blue light-emitting diode (LED) lamps, 3) green LED lamps, 4) blue LED switching to green at 10 d of age, 5) blue LED switching to green at 20 d of age, 6) green LED switching to blue at 10 d of age, and 7) green LED switching to blue at 20 d of age. There were 8 pens for treatment 1, and 4 pens for each of the other treatments. The light schedule was 23L:1D, and intensity was 0.1 watts/m2. BW and feed consumption were recorded. Green light birds were significantly heavier at 4 d of age. Switching light at 10 d of age from green to blue caused a further increase in BW. This improved growth was maintained until the end of the experiment. Light switching from blue to green at 20 d of age also improved growth as compared with white light. Average feed efficiency and mortality rate did not differ between groups. No association was observed among light treatment, performance, and plasma triiodothyronine concentration. We suggest that green light stimulated growth of birds at early age, and shifting birds to a different light environment at 10 or 20 d of age might further stimulate growth. PMID:15141845

  20. Functional inactivation of lymphocytes by methylene blue with visible light.

    PubMed

    Zhang, Bo; Cheng, Zhenzhen; Mo, Qin; Wang, Li; Wang, Xun; Wu, Xiaofei; Jia, Yao; Huang, Yuwen

    2015-10-01

    Transfusion of allogeneic white blood cells (WBCs) may cause adverse reactions in immunocompromised recipients, including transfusion-associated graft-versus-host disease (TA-GVHD), which is often fatal and incurable. In this study, the in vitro effect of methylene blue with visible light (MB + L) treatment on lymphocyte proliferation and cytokine production was measured to investigate whether MB + L can be used to prevent immune reactions that result from transfused lymphocytes. WBCs and 3 μM of MB were mixed and transferred into medical PVC bags, which were then exposed to visible light. Gamma irradiation was conducted as a parallel positive control. The cells without treatment were used as untreated group. All the groups were tested for the ability of cell proliferation and cytokine production upon stimulation. After incubation with mitogen phytohemagglutinin (PHA) or plate-bound anti-CD3 plus anti-CD28, the proliferation of MB + L/gamma-irradiation treated lymphocytes was significantly inhibited (P < 0.01) as compared to the untreated ones; the proliferation inhibitive rate of the MB + L group was even higher than that of gamma-irradiated cells (73.77% ± 28.75% vs. 44.72% ± 38.20%). MB + L treated cells incubated up to 7 days with PHA also showed no significant proliferation. The levels of TNF-α, IFN-γ, IL-6, IL-8, IL-10 and IL-1β present in the supernatant of MB + L treated lymphocytes upon stimulation were significantly lower than those of untreated lymphocytes. These results demonstrated that MB + L treatment functionally and irreversibly inactivated lymphocytes by inhibiting lymphocyte proliferation and the production of cytokines. MB + L treatment might be a promising method for the prevention of adverse immune responses caused by WBCs. PMID:26295729

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

    NASA Astrophysics Data System (ADS)

    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.

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

    NASA Technical Reports Server (NTRS)

    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.

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

    PubMed Central

    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

  4. 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

    SciTech Connect

    Quinones, M.A.; Lu, Zhenmin; Zeiger, E.

    1996-03-05

    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 the red light-stimulated fluorescence quenching by up to 50%. In contrast, added blue light did not alter the red light-stimulated quenching from abaxial (lower) guard cells. This response pattern paralleled the blue light sensitivity of stomatal opening in the two leaf surfaces. An action spectrum for the blue light-induced enhancement of the red light-stimulated quenching showed a major peak at 450 nm and two minor peaks at 420 and 470 nm. This spectrum matched closely an action spectrum for blue light-stimulated stomatal opening. Coleoptile chloroplasts also showed an enhancement by blue light of red light-stimulated quenching. The action spectrum of this response, showing a major peak at 450 nm, a minor peak at 470 nm, and a shoulder at 430 nm, closely matched an action spectrum for blue light-stimulated coleoptile phototropism. Both action spectra match the absorption spectrum of zeaxanthin, a chloroplastic carotenoid recently implicated in blue light photoreception of both guard cells and coleoptiles. The remarkable similarity between the action spectra for the blue light responses of guard cells and coleoptile chloroplasts and the spectra for blue light-stimulated stomatal opening and phototropism, coupled to the recently reported evidence on a role of zeaxanthin in blue light photoreception, indicates that the guard cell and coleoptile chloroplasts specialize in sensory transduction. 28 refs. 4 figs.

  5. Rapid-Response Low Infrared Emission Broadband Ultrathin Plasmonic Light Absorber

    PubMed Central

    Tagliabue, Giulia; Eghlidi, Hadi; Poulikakos, Dimos

    2014-01-01

    Plasmonic nanostructures can significantly advance broadband visible-light absorption, with absorber thicknesses in the sub-wavelength regime, much thinner than conventional broadband coatings. Such absorbers have inherently very small heat capacity, hence a very rapid response time, and high light power-to-temperature sensitivity. Additionally, their surface emissivity can be spectrally tuned to suppress infrared thermal radiation. These capabilities make plasmonic absorbers promising candidates for fast light-to-heat applications, such as radiation sensors. Here we investigate the light-to-heat conversion properties of a metal-insulator-metal broadband plasmonic absorber, fabricated as a free-standing membrane. Using a fast IR camera, we show that the transient response of the absorber has a characteristic time below 13 ms, nearly one order of magnitude lower than a similar membrane coated with a commercial black spray. Concurrently, despite the small thickness, due to the large absorption capability, the achieved absorbed light power-to-temperature sensitivity is maintained at the level of a standard black spray. Finally, we show that while black spray has emissivity similar to a black body, the plasmonic absorber features a very low infra-red emissivity of almost 0.16, demonstrating its capability as selective coating for applications with operating temperatures up to 400°C, above which the nano-structure starts to deform. PMID:25418040

  6. Rapid-response low infrared emission broadband ultrathin plasmonic light absorber.

    PubMed

    Tagliabue, Giulia; Eghlidi, Hadi; Poulikakos, Dimos

    2014-01-01

    Plasmonic nanostructures can significantly advance broadband visible-light absorption, with absorber thicknesses in the sub-wavelength regime, much thinner than conventional broadband coatings. Such absorbers have inherently very small heat capacity, hence a very rapid response time, and high light power-to-temperature sensitivity. Additionally, their surface emissivity can be spectrally tuned to suppress infrared thermal radiation. These capabilities make plasmonic absorbers promising candidates for fast light-to-heat applications, such as radiation sensors. Here we investigate the light-to-heat conversion properties of a metal-insulator-metal broadband plasmonic absorber, fabricated as a free-standing membrane. Using a fast IR camera, we show that the transient response of the absorber has a characteristic time below 13 ms, nearly one order of magnitude lower than a similar membrane coated with a commercial black spray. Concurrently, despite the small thickness, due to the large absorption capability, the achieved absorbed light power-to-temperature sensitivity is maintained at the level of a standard black spray. Finally, we show that while black spray has emissivity similar to a black body, the plasmonic absorber features a very low infra-red emissivity of almost 0.16, demonstrating its capability as selective coating for applications with operating temperatures up to 400°C, above which the nano-structure starts to deform. PMID:25418040

  7. Rapid-Response Low Infrared Emission Broadband Ultrathin Plasmonic Light Absorber

    NASA Astrophysics Data System (ADS)

    Tagliabue, Giulia; Eghlidi, Hadi; Poulikakos, Dimos

    2014-11-01

    Plasmonic nanostructures can significantly advance broadband visible-light absorption, with absorber thicknesses in the sub-wavelength regime, much thinner than conventional broadband coatings. Such absorbers have inherently very small heat capacity, hence a very rapid response time, and high light power-to-temperature sensitivity. Additionally, their surface emissivity can be spectrally tuned to suppress infrared thermal radiation. These capabilities make plasmonic absorbers promising candidates for fast light-to-heat applications, such as radiation sensors. Here we investigate the light-to-heat conversion properties of a metal-insulator-metal broadband plasmonic absorber, fabricated as a free-standing membrane. Using a fast IR camera, we show that the transient response of the absorber has a characteristic time below 13 ms, nearly one order of magnitude lower than a similar membrane coated with a commercial black spray. Concurrently, despite the small thickness, due to the large absorption capability, the achieved absorbed light power-to-temperature sensitivity is maintained at the level of a standard black spray. Finally, we show that while black spray has emissivity similar to a black body, the plasmonic absorber features a very low infra-red emissivity of almost 0.16, demonstrating its capability as selective coating for applications with operating temperatures up to 400°C, above which the nano-structure starts to deform.

  8. Comparison between blue lasers and light-emitting diodes for future solid-state lighting: Comparison between blue lasers and light-emitting diodes

    SciTech Connect

    Wierer, Jonathan J.; Tsao, Jeffrey Y.; Sizov, Dmitry S.

    2013-08-01

    Solid-state lighting (SSL) is now the most efficient source of high color quality white light ever created. Nevertheless, the blue InGaN light-emitting diodes (LEDs) that are the light engine of SSL still have significant performance limitations. Foremost among these is the decrease in efficiency at high input current densities widely known as “efficiency droop.” Efficiency droop limits input power densities, contrary to the desire to produce more photons per unit LED chip area and to make SSL more affordable. Pending a solution to efficiency droop, an alternative device could be a blue laser diode (LD). LDs, operated in stimulated emission, can have high efficiencies at much higher input power densities than LEDs can. In this article, LEDs and LDs for future SSL are explored by comparing: their current state-of-the-art input-power-density-dependent power-conversion efficiencies; potential improvements both in their peak power-conversion efficiencies and in the input power densities at which those efficiencies peak; and their economics for practical SSL.

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

    DOEpatents

    Vogl, O.; Li, S.

    1983-10-06

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

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

    NASA Technical Reports Server (NTRS)

    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.

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

    PubMed Central

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

    2013-01-01

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

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

    PubMed Central

    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

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

    PubMed

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

    2016-05-01

    Storing reclaimed water in lakes is a widely used method of accommodating changes in the consumption of reclaimed water during wastewater reclamation and reuse. Solar light serves as an important function in degrading pollutants during storage, and its effect on dissolved organic matter (DOM) was investigated in this study. Solar light significantly decreased the UV254 absorbance and fluorescence (FLU) intensity of reclaimed water. However, its effect on the dissolved organic carbon (DOC) value of reclaimed water was very limited. The decrease in the UV254 absorbance intensity and FLU excitation-emission matrix regional integration volume (FLU volume) of reclaimed water during solar light irradiation was fit with pseudo-first order reaction kinetics. The decrease of UV254 absorbance was much slower than that of the FLU volume. Ultraviolet light in solar light had a key role in decreasing the UV254 absorbance and FLU intensity during solar light irradiation. The light fluence-based removal kinetic constants of the UV254 and FLU intensity were independent of light intensity. The peaks of the UV254 absorbance and FLU intensity with an apparent molecular weight (AMW) of 100Da to 2000Da decreased after solar irradiation, whereas the DOC value of the major peaks did not significantly change. PMID:27155416

  14. System Responses to Equal Doses of Photosynthetically Usable Radiation of Blue, Green, and Red Light in the Marine Diatom Phaeodactylum tricornutum

    PubMed Central

    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. PMID:25470731

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

    PubMed

    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. PMID:25470731

  16. Guard Cell Chloroplasts Are Essential for Blue Light-Dependent Stomatal Opening in Arabidopsis

    PubMed Central

    Suetsugu, Noriyuki; Takami, Tsuneaki; Ebisu, Yuuta; Watanabe, Harutaka; Iiboshi, Chihoko; Doi, Michio; Shimazaki, Ken-ichiro

    2014-01-01

    Blue light (BL) induces stomatal opening through the activation of H+-ATPases with subsequent ion accumulation in guard cells. In most plant species, red light (RL) enhances BL-dependent stomatal opening. This RL effect is attributable to the chloroplasts of guard cell, the only cells in the epidermis possessing this organelle. To clarify the role of chloroplasts in stomatal regulation, we investigated the effects of RL on BL-dependent stomatal opening in isolated epidermis, guard cell protoplasts, and intact leaves of Arabidopsis thaliana. In isolated epidermal tissues and intact leaves, weak BL superimposed on RL enhanced stomatal opening while BL alone was less effective. In guard cell protoplasts, RL enhanced BL-dependent H+-pumping and DCMU, a photosynthetic electron transport inhibitor, eliminated this effect. RL enhanced phosphorylation levels of the H+-ATPase in response to BL, but this RL effect was not suppressed by DCMU. Furthermore, DCMU inhibited both RL-induced and BL-dependent stomatal opening in intact leaves. The photosynthetic rate in leaves correlated positively with BL-dependent stomatal opening in the presence of DCMU. We conclude that guard cell chloroplasts provide ATP and/or reducing equivalents that fuel BL-dependent stomatal opening, and that they indirectly monitor photosynthetic CO2 fixation in mesophyll chloroplasts by absorbing PAR in the epidermis. PMID:25250952

  17. Guard cell chloroplasts are essential for blue light-dependent stomatal opening in Arabidopsis.

    PubMed

    Suetsugu, Noriyuki; Takami, Tsuneaki; Ebisu, Yuuta; Watanabe, Harutaka; Iiboshi, Chihoko; Doi, Michio; Shimazaki, Ken-ichiro

    2014-01-01

    Blue light (BL) induces stomatal opening through the activation of H+-ATPases with subsequent ion accumulation in guard cells. In most plant species, red light (RL) enhances BL-dependent stomatal opening. This RL effect is attributable to the chloroplasts of guard cell, the only cells in the epidermis possessing this organelle. To clarify the role of chloroplasts in stomatal regulation, we investigated the effects of RL on BL-dependent stomatal opening in isolated epidermis, guard cell protoplasts, and intact leaves of Arabidopsis thaliana. In isolated epidermal tissues and intact leaves, weak BL superimposed on RL enhanced stomatal opening while BL alone was less effective. In guard cell protoplasts, RL enhanced BL-dependent H+-pumping and DCMU, a photosynthetic electron transport inhibitor, eliminated this effect. RL enhanced phosphorylation levels of the H+-ATPase in response to BL, but this RL effect was not suppressed by DCMU. Furthermore, DCMU inhibited both RL-induced and BL-dependent stomatal opening in intact leaves. The photosynthetic rate in leaves correlated positively with BL-dependent stomatal opening in the presence of DCMU. We conclude that guard cell chloroplasts provide ATP and/or reducing equivalents that fuel BL-dependent stomatal opening, and that they indirectly monitor photosynthetic CO2 fixation in mesophyll chloroplasts by absorbing PAR in the epidermis. PMID:25250952

  18. PAS/LOV proteins: A proposed new class of plant blue light receptor.

    PubMed

    Ogura, Yasunobu; Tokutomi, Satoru; Wada, Masamitsu; Kiyosue, Tomohiro

    2008-11-01

    The light, oxygen or voltage (LOV) domain belongs to the Per-ARNT-Sim (PAS) superfamily of domains, and functions with the flavin chromophore as a module for sensing blue light in plants and fungi. The Arabidopsis thaliana PAS/LOV proteins (PLPs), of unknown function, possess an N-terminal PAS domain and a C-terminal LOV domain. Our recent analysis using yeast two-hybrid and Escherichia coli protein production systems reveals that the interactions of Arabidopsis PLPs with several proteins diminish under blue light illumination and that the PLP LOV domain may bind to a flavin chromophore. These results suggest that PLP functions as a blue light receptor. Homologs of PLP exist in rice, tomato and moss. The LOV domains of these PLP homologs form a distinct group in phylogenetic analysis. These facts suggest that PLP belongs to a new class of plant blue light receptor. PMID:19704421

  19. Comparison of Blue Light-Filtering IOLs and UV Light-Filtering IOLs for Cataract Surgery: A Meta-Analysis

    PubMed Central

    Zhu, Xiao-feng; Zou, Hai-dong; Yu, Yong-fu; Sun, Qian; Zhao, Nai-qing

    2012-01-01

    Background A number of published randomized controlled trials have been conducted to evaluate visual performance of blue light-filtering intraocular lenses (IOL) and UV light-filtering intraocular lenses (IOL) after cataract phacoemulsification surgery. However, results have not always been consistent. Therefore, we carried out a meta-analysis to compare the effectiveness of blue light-filtering IOLs versus UV light-filtering IOLs in cataract surgery. Methods and Findings Comprehensive searches of PubMed, Embase, Cochrane Library and the Chinese BioMedical literature databases were performed using web-based search engines. Fifteen trials (1690 eyes) were included for systematic review, and 11 of 15 studies were included in this meta-analysis. The results showed that there were no significant differences in postoperative mean best corrected visual acuity, contrast sensitivity, overall color vision, or in the blue light spectrum under photopic light conditions between blue light-filtering IOLs and UV light-filtering IOLs [WMD = −0.01, 95%CI (−0.03, 0.01), P = 0.46; WMD = 0.07, 95%CI (−0.04, 0.19), P = 0.20; SMD = 0.14, 95%CI (−0.33, 0.60), P = 0.566; SMD = 0.20, 95%CI (−0.04, 0.43), P = 0.099]. However, color vision with blue light-filtering IOLs was significantly reduced in the blue light spectrum under mesopic light conditions [SMD = 0.74, 95%CI (0.29, 1.18), P = 0.001]. Conclusion This meta-analysis demonstrates that postoperative visual performance with blue light-filtering IOLs is approximately equal to that of UV light-filtering IOLs after cataract surgery, but color vision with blue light-filtering IOLs demonstrated some compromise in the blue light spectrum under mesopic light conditions. PMID:22412976

  20. Measurements of a prototype synchrotron radiation pumped absorber for future light sources

    NASA Astrophysics Data System (ADS)

    Chou, T. S.; Foerster, C. L.; Halama, H.; Lanni, C.

    1988-09-01

    In the new generation of advanced synchrotron light sources, the conventional concept of distributed pumping is no longer suitable for removing the gas load caused by photon stimulated desorption (PSD). A new concept using a combination of photon absorber and pumping station has been designed, constructed, and installed in the U10B beam line at the VUV ring of the National Synchrotron Light Source. The system consists of an electrically insulated water cooled copper block, a titanium sublimation pump, calibrated BA gauges, a calibrated RGA, and a known conductance. A photon beam 10 milliradian wide and 3.26 milliradian high, having critical energy of 500 eV, is directed on the absorber. PSD yield is studied as a function of total beam dose and absorber surface preparation. The results from this experiment, pump characteristics, design of an absorber pump for future light sources, and the pressure improvement factors will be presented.

  1. Measurements of a prototype synchrotron radiation pumped absorber for future light sources

    SciTech Connect

    Chou, T.S.; Foerster, C.L.; Halama, H.; Lanni, C.

    1988-01-01

    In the new generation of advanced synchrotron light sources, the conventional concept of distributed pumping is no longer suitable for removing the gas load caused by photon stimulated desorption (PSD). A new concept using a combination of photon absorber and pumping station has been designed, constructed, and installed in the U1OB beam line at the VUV ring of the National Synchrotron Light Source. The system consists of an electrically insulated water cooled copper block, a titanium sublimation pump, calibrated BA gauges, a calibrated RGA, and a known conductance. A photon beam 10 milliradian wide and 3.26 milliradian high, having critical energy of 500 eV, is directed on the absorber. PSD yield is studied as a function of total beam dose and absorber surface preparation. The results from this experiment, pump characteristics, design of an absorber pump for future light sources, and the pressure improvement factors will be presented. 5 refs., 7 figs., 1 tab.

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

    PubMed Central

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

    2015-01-01

    Background 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. Methodology/Principal Findings 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. Conclusions Twice-daily treatment with blue light without a photosensitizer is a promising mechanism for the inhibition of matrix-rich biofilm development. PMID:26230333

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

    PubMed Central

    O'Toole, Martina; Diamond, Dermot

    2008-01-01

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

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

    PubMed

    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 (<20lux). Participants were randomized to 3 hours of 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. PMID:27191727

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

    PubMed Central

    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 (<20lux). Participants were randomized to 3 hours of 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. PMID:27191727

  6. Host Engineering for High Quantum Efficiency Blue and White Fluorescent Organic Light-Emitting Diodes.

    PubMed

    Song, Wook; Lee, Inho; Lee, Jun Yeob

    2015-08-01

    High quantum efficiency in blue and white fluorescence organic light-emitting diodes is achieved by developing a novel device architecture with fluorescent emitters doped in a thermally activated delayed fluorescent emitter as a host material. PMID:26078193

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

    PubMed Central

    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

  8. Proceedings of the 5th International Symposium on Blue Laser and Light Emitting Diodes (ISBLLED-2004)

    NASA Astrophysics Data System (ADS)

    Suh, Eun-Kyung; Yoon, Euijoon; Lee, Hyung Jae

    2004-09-01

    The 5th International Symposium on Blue Laser and Light Emitting Diodes (ISBLLED-2004) was held in Gyeongju, Korea, 15-19 March 2004. The purpose of the symposium was to provide a forum for scientists and engineers to discuss recent progress and future trends in the rapidly advancing wide band gap semiconductor science and technologies and their applications in blue laser and light emitting diodes.

  9. Hot Dust Obscured Galaxies with Excess Blue Light: Dual AGN or Single AGN Under Extreme Conditions?

    NASA Astrophysics Data System (ADS)

    Assef, R. J.; Walton, D. J.; Brightman, M.; Stern, D.; Alexander, D.; Bauer, F.; Blain, A. W.; Diaz-Santos, T.; Eisenhardt, P. R. M.; Finkelstein, S. L.; Hickox, R. C.; Tsai, C.-W.; Wu, J. W.

    2016-03-01

    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⊙ yr-1. Deep polarimetry observations could confirm the reflection hypothesis.

  10. Biocidal activity of a light-absorbing fluorescent conjugated polyelectrolyte.

    PubMed

    Lu, Liangde; Rininsland, Frauke H; Wittenburg, Shannon K; Achyuthan, Komandoor E; McBranch, Duncan W; Whitten, David G

    2005-10-25

    Herein we describe studies that indicate a cationic conjugated polyelectrolyte shows biocidal activity against gram-negative bacteria (Escherichia coli, E. coli, BL21, with plasmids for Azurin and ampicillin resistance) and gram-positive bacterial spores (Bacillus anthracis, Sterne, B. anthracis, Sterne). These studies were carried out with aqueous suspensions of the conjugated polyelectrolyte, with the polyelectrolyte in supported formats and with samples in which the conjugated polyelectrolyte was coated on the bacteria. The results are interesting in that the biocidal activity is light-induced and appears effective due to the ability of the conjugated polyelectrolyte to form a surface coating on both types of bacteria. The effects observed here should be general and suggest that a range of conjugated polyelectrolytes in different formulations may provide a useful new class of biocides for both dark and light-activated applications. PMID:16229539

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

    NASA Technical Reports Server (NTRS)

    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.

  12. Influence of blue light on photoreceptors in a live retinal explant system

    PubMed Central

    Roehlecke, Cora; Schumann, Ulrike; Ader, Marius; Knels, Lilla

    2011-01-01

    Purpose The present study was performed to investigate the early effects of blue light irradiation of photoreceptors in retinal explant cultures. Methods Murine retinal explant cultures were irradiated with visible blue light (405 nm) with an output power of 1 mW/cm2. Dihydroethidium was used to determine the production of reactive oxygen species. Morphological alterations of photoreceptor outer segments were determined by live imaging microscopy with mitochondrial dye JC-1. Transmission and scanning electron microscopy were used for ultrastructural evaluations. Cell death in the retina was assessed by the terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate (dUTP) nick end labeling (TUNEL) assay method. Results Live retinal explants displayed an increase in reactive oxygen species production, as revealed by fluorescent dihydroethidium products in photoreceptor cells after 30 min of blue light exposure. After 3 h of exposure, blue light caused disorganization of the normally neatly stacked outer segments of living photoreceptors. Ultrastructural analysis revealed breaks in the cell membrane surrounding the outer segments, especially in the middle section. The outer segments appeared tortuous, and the lamellar structures had been disrupted. TUNEL-staining revealed that long-term blue light exposure induced photoreceptor cell death. Conclusions In vitro blue light irradiation of retinal explants is a suitable model system for investigating early ultrastructural changes, as well as damage that leads to cell death in photoreceptor cells. PMID:21527999

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

    PubMed Central

    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. Images Figure 1 PMID:11538049

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

    NASA Technical Reports Server (NTRS)

    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.

  15. Extending "Deep Blue" aerosol retrieval coverage to cases of absorbing aerosols above clouds: Sensitivity analysis and first case studies

    NASA Astrophysics Data System (ADS)

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

    2016-05-01

    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 ˜25-50% (with lower uncertainties for more strongly absorbing aerosol types) and COD with an uncertainty ˜10-20%, 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.

  16. The antimicrobial properties of light-activated polymers containing methylene blue and gold nanoparticles.

    PubMed

    Perni, Stefano; Piccirillo, Clara; Pratten, Jonathan; Prokopovich, Polina; Chrzanowski, Wojciech; Parkin, Ivan P; Wilson, Michael

    2009-01-01

    We report the formation of polysiloxane polymers containing embedded methylene blue and gold nanoparticles incorporated by a swell-encapsulation-shrink method. These polymers show significant antimicrobial activity against methicillin-resistant Staphylococcus aureus and Escherichia coli with up to a 3.5 log(10) reduction in the viable count when exposed for 5 min to light from a low power 660 nm laser. The bacterial kill is due to the light-induced production of singlet oxygen and other reactive oxygen species by the methylene blue. Interestingly, the presence of 2 nm gold nanoparticles significantly enhanced the ability of the methylene blue to kill bacteria. PMID:18838166

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

    NASA Astrophysics Data System (ADS)

    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

  18. Blue light regulates the accumulation of two psbD-psbC transcripts in barley chloroplasts.

    PubMed Central

    Gamble, P E; Mullet, J E

    1989-01-01

    Synthesis of D2, a Photosystem II reaction center protein encoded by psbD, is differentially maintained during light-induced chloroplast maturation. The continued synthesis of D2 is paralleled by selective light-induced accumulation of two psbD-psbC transcripts which share a common 5' terminus. In the present study, we examine the nature of the photoreceptor and the fluence requirement for psbD-psbC transcript induction. The light-induced change in psbD-psbC RNA population can be detected between 1 and 2 h after 4.5 day old dark-grown barley seedlings are transferred to the light. Light-induced transcript accumulation occurs normally in the chlorophyll-deficient barley mutant, xan-f10, indicating that light-activated chlorophyll formation and photosynthesis are not required for RNA induction. High fluence blue light fully induces psbD-psbC transcript accumulation; low or high fluence red or far-red light do not. However, psbD-psbC transcript accumulation elicited by blue light pulses can be partially attenuated if far-red light is given immediately following the blue light treatment. Thus, although blue light is needed to initiate transcript accumulation, phytochrome modulates the amplitude of the response. Pretreatment of dark-grown plants with cycloheximide blocks light-induced psbD-psbC transcript accumulation. This could implicate a blue-light responsive nuclear gene in the light-induced accumulation of the two psbD-psbC transcripts. Images PMID:2479534

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

    PubMed Central

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

    2015-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-11-01

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

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

    PubMed

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

    2015-01-01

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

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

    PubMed

    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 < 0.05) decrease compared to the non-treated groups after the 2 or 6 h recovery period. Growth rates of planktonic and biofilm cells indicated a significant reduction in the growth rate of the violet-blue light-treated groups grown in TSB and TSBS. Biofilm viability assays confirmed a statistically significant difference between violet-blue light-treated and non-treated groups in TSB and TSBS. Visible violet-blue light of the electromagnetic spectrum has the ability to inhibit S. 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. PMID:27278805

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

    SciTech Connect

    Arto V. Nurmikko; Jung Han

    2004-10-01

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

  4. The core interthreshold zone during exposure to red and blue light

    PubMed Central

    2013-01-01

    Background This study tested the hypothesis that the core interthreshold zone (CIZ) changes during exposure to red or blue light via the non-visual pathway, because it is known that light intensity affects the central nervous system. We conducted a series of human experiments with 5 or 10 male subjects in each experiment. Methods The air temperature in the climatic chamber was maintained at 20 to 24°C. The subjects wore suits perfused with 25°C water at a rate of 600 cm3/min. They exercised on an ergometer at 50% of their maximum work rate for 10 to 15 minutes until sweating commenced, and then remained continuously seated without exercise until their oxygen uptake increased. The rectal temperature and skin temperatures at four sites were monitored using thermistors. The sweating rate was measured at the forehead with a sweat rate monitor. Oxygen uptake was monitored with a gas analyzer. The subjects were exposed to red or blue light at 500 lx and 1000 lx in both summer and winter. Results The mean CIZs at 500 lx were 0.23 ± 0.16°C under red light and 0.20 ± 0.10°C under blue light in the summer, and 0.19 ± 0.20°C under red light and 0.26 ± 0.24°C under blue light in the winter. The CIZs at 1000 lx were 0.18 ± 0.14°C under red light and 0.15 ± 0.20°C under blue light in the summer, and 0.52 ± 0.18°C under red light and 0.71 ± 0.28°C under blue light in the winter. A significant difference (P <0.05) was observed in the CIZs between red and blue light at 1000 lx in the winter, and significant seasonal differences under red light (P <0.05) and blue light (P <0.01) were also observed at 1000 lx. Conclusions The present study demonstrated that dynamic changes in the physiological effects of colors of light on autonomic functions via the non-visual pathway may be associated with the temperature regulation system. PMID:23587209

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

    NASA Technical Reports Server (NTRS)

    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.

  6. Cryptochromes Interact Directly with PIFs to Control Plant Growth in Limiting Blue Light.

    PubMed

    Pedmale, Ullas V; Huang, Shao-Shan Carol; Zander, Mark; Cole, Benjamin J; Hetzel, Jonathan; Ljung, Karin; Reis, Pedro A B; Sridevi, Priya; Nito, Kazumasa; Nery, Joseph R; Ecker, Joseph R; Chory, Joanne

    2016-01-14

    Sun-loving plants have the ability to detect and avoid shading through sensing of both blue and red light wavelengths. Higher plant cryptochromes (CRYs) control how plants modulate growth in response to changes in blue light. For growth under a canopy, where blue light is diminished, CRY1 and CRY2 perceive this change and respond by directly contacting two bHLH transcription factors, PIF4 and PIF5. These factors are also known to be controlled by phytochromes, the red/far-red photoreceptors; however, transcriptome analyses indicate that the gene regulatory programs induced by the different light wavelengths are distinct. Our results indicate that CRYs signal by modulating PIF activity genome wide and that these factors integrate binding of different plant photoreceptors to facilitate growth changes under different light conditions. PMID:26724867

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

    PubMed

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

    2015-02-01

    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. PMID:25836102

  8. Enhanced optical waveguide light mode spectroscopy via detection of fluorophore absorbance

    NASA Astrophysics Data System (ADS)

    Halter, Martin; Gabi, Michael; Textor, Marcus; Vörös, Janos; Grandin, H. Michelle

    2006-10-01

    A novel technique based on surface sensitive absorbance detection using an optical waveguide light mode spectroscopy (OWLS) instrument is presented. The proof of concept for this extension of a standard technique is demonstrated by painting an increasing number of ink lines on a waveguide, perpendicular to the light path, while monitoring the outcoupled light intensity. Furthermore, by the adsorption of poly(L-lysine)-graft-poly(ethylene glycol) as a model system with contents of 5%, 10%, 25%, and 50% labeled polymer, the in situ performance is demonstrated, and the absorbance signal is calibrated such that it can be converted into adsorbed mass. The simultaneous detection of labeled and label-free species allows for the study of complex experimental setups whereby monitoring of adsorption, desorption, and even exchange processes becomes possible. The sensitivity of the absorbance detection exceeds standard OWLS by one to two orders of magnitude.

  9. Phase Delaying the Human Circadian Clock with Blue-Enriched Polychromatic Light

    PubMed Central

    Smith, Mark R.; Eastman, Charmane I.

    2009-01-01

    The human circadian system is maximally sensitive to short-wavelength (blue) light. In a previous study we found no difference between the magnitude of phase advances produced by bright white versus bright blue-enriched light using light boxes in a practical protocol that could be used in the real world. Since the spectral sensitivity of the circadian system may vary with a circadian rhythm, we tested whether the results of our recent phase-advancing study hold true for phase delays. In a within-subjects counterbalanced design, this study tested whether bright blue-enriched polychromatic light (17000 K, 4000 lux) could produce larger phase delays than bright white light (4100 K, 5000 lux) of equal photon density (4.2 × 1015 photons/cm2/sec). Healthy young subjects (n = 13) received a 2 h phase delaying light pulse before bedtime combined with a gradually delaying sleep/dark schedule on each of 4 consecutive treatment days. On the first treatment day the light pulse began 3 h after the dim light melatonin onset (DLMO). An 8 h sleep episode began at the end of the light pulse. Light treatment and the sleep schedule were delayed 2 h on each subsequent treatment day. A circadian phase assessment was conducted before and after the series of light treatment days to determine the time of the DLMO and DLMOff. Phase delays in the blue-enriched and white conditions were not significantly different (DLMO: −4.45 ± 2.02 versus −4.48 ± 1.97 h; DLMOff: −3.90 ± 1.97 versus −4.35 ± 2.39 h, respectively). These results indicate that at light levels commonly used for circadian phase shifting blue-enriched polychromatic light is no more effective than the white polychromatic lamps of a lower correlated color temperature (CCT) for phase delaying the circadian clock. PMID:19444751

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

    NASA Technical Reports Server (NTRS)

    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.

  11. White Organic Light-Emitting Diode Using Blue-Light-Emitting Zn(HPB)2 Material

    NASA Astrophysics Data System (ADS)

    Kim, Dong-Eun; Kim, Won-Sam; Lee, Burm-Jong; Kwon, Young-Soo

    2007-04-01

    A novel blue light emitter, zinc(II) [2-(2-hydroxyphenyl)benzoxazole] [Zn(HPB)2], has been synthesized and evaluated in organic light-emitting diodes (OLED). Hereby, an OLED with a white light emission and a high color stability using Zn(HPB)2 and a layer of tris(8-quinolinolato) aluminum (Alq3) doped with 4-(dicyanomethylene)-2-t-butyl-6(1,1,7,7-tetramethyljulolidyl-9-enyl)-4H-pyran (DCJTB) (Alq3:DCJTB) as emitters has been demonstrated. The structure of this OLED is indium-tin-oxide (ITO)/N,N'-bis-(1-naphthl)-diphenyl-1,1'-biphenyl-4,4'-diamine (NPB; 40 nm)/Zn(HPB)2 (40 nm)/Alq3:DCJTB (40 nm)/LiF/Al. The Commission Internationale de l’Eclairage (CIE) coordinates of the white emission are (0.32, 0.33) at an applied voltage of 14 V. The photoluminescence (PL) and electroluminescence (EL) spectra of Zn(HPB)2 showed emission peaks at a wavelength of 455 nm.

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

    SciTech Connect

    Arto V. Nurmikko; Jung Han

    2005-09-30

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

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

    NASA Astrophysics Data System (ADS)

    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.

  14. Red and blue lights induced oxidative stress tolerance promote cadmium rhizocomplexation in Oryza sativa.

    PubMed

    Sebastian, Abin; Prasad, M N V

    2014-08-01

    Cadmium (Cd) accumulation and related stress responses have been investigated in red, blue and white lights exposed Oryza sativa L. cv MTU 7029. Cd translocation was reduced significantly by red and blue lights. Increase in amount of organic acids, thiols, and nutrients in the roots that cause Cd rhizocomplexation was the reason for reduction in Cd translocation. These effects were due to higher efficiency to perform photosynthesis and transpiration under red or blue lights compare with white light during Cd stress. Increased photosynthetic assimilate turnover was witnessed as a function of sugar content. Amount of redox regulators such as glutathione and ascorbate were also increased under red and blue light exposure. Together with up regulation of antioxidant enzyme activities, these metabolites ensured redox balance in presence of reactive oxygen species produced due to Cd toxicity. Protection of photosynthesis from Cd inducible oxidative stress ensured supplies of sugar intermediates essential for the synthesis of metal chelators in roots. Therefore, it was inferred that red and blue lights promote Cd rhizocomplexation and ameliorated Cd stress in rice seedlings. PMID:24444775

  15. The influence of sublethal blue light exposure on human RPE cells

    PubMed Central

    Schaller, Annette; Knels, Lilla; Funk, Richard H.W.

    2009-01-01

    Purpose To evaluate the in vitro response of retinal pigment epithelial (RPE) cells to a nonlethal dose of blue light. Methods The human RPE cell line ARPE-19 was irradiated with blue light (405 nm) at an output power of 1 mW/cm2 or 0.3 mW/cm2. The following parameters were studied: metabolic activity; apoptosis; reactive oxygen species (ROS) production; mitochondrial membrane potential (MMP); ultrastructural changes of mitochondria; production of advanced glycation endproducts (AGEs); and stress-related cellular proteins. Results Nonlethal doses of blue light irradiation significantly reduced ARPE-19 metabolic activity and MMP while increasing intracellular ROS levels and expression of stress-related proteins heme oxygenase-1 (HO-1), osteopontin, heat shock protein 27 (Hsp-27), manganese superoxide dismutase (SOD-Mn), and cathepsin D. Blue light irradiation also induced ultrastructural conformation changes in mitochondria, resulting in the appearance of giant mitochondria after 72 h. We further found enhanced formation of AGEs, particularly Nε-(carboxymethyl) lysine (CML) modifications, and a delay in the cell cycle. Conclusions ARPE-19 cells avoid cell death and recover from blue light irradiation by activating a host of defense mechanisms while simultaneously triggering cellular stress responses that may be involved in RPE disease development. Continuous light exposure can therefore detrimentally affect metabolically stressed RPE cells. This may have implications for pathogenesis of age-related macular degeneration. PMID:19784391

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

    PubMed

    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. PMID:25711821

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

    PubMed

    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. PMID:11541667

  18. Efficient blue light generation using periodically poled stoichiometric lithium tantalate via resonant frequency doubling

    NASA Astrophysics Data System (ADS)

    Khademian, Ali; Jadhav, Shilpa; Shiner, David

    2014-05-01

    Convenient high power blue diode lasers with single frequency operation are still under developments and are not as well developed and cost effective as IR laser sources. Harmonic generation of IR lasers provide a viable alternative source of blue and UV light. Magnesium oxide doped periodically poled Stoichiometric Lithium Tantalate (PPMgO:SLT) has been reported to have the lowest blue, IR and blue induced IR absorption (BLIIRA) among ferroelectric crystals such as Lithium Niobate (PPLN) and Potassium Titanyl Phosphate (PPKTP). All these properties, along with higher thermal conductivity, make this crystal an excellent candidate for efficient blue light generation using second harmonic generation (SHG) in a resonant buildup cavity. Efficient resonant doubling is very sensitive to various cavity and crystal loss mechanisms. Recently we obtained 400 mW of blue light at 486 nm with net conversion efficiency of 77% using a 515 mW fiber grating stabilized IR source. Sources of conversion loss have been identified and evaluated with various methods in our investigation. These include reflection, scattering, absorption, and polarization rotation of IR light in the crystal, as well as mode mismatching and spherical aberration due to focusing lenses. The locking and electronic control functions of the cavity are automated using an internally mounted single chip microcontroller with embedded DSP (digital signal processor). Work is supported by NSF grant.

  19. Blue and green light-induced phototropism in Arabidopsis thaliana and Lactuca sativa L. seedlings

    SciTech Connect

    Steinitz, B.; Ren, Z.; Poff, K.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 wavelengths 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. The authors advise care in the use of green safelights for studies of phototropism.

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

    NASA Astrophysics Data System (ADS)

    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

  1. Effects of spectral parameters on the light properties of red-green-blue white light-emitting diodes.

    PubMed

    Xu, Mingsheng; Zhang, Haoxiang; Zhou, Quanbin; Wang, Hong

    2016-06-01

    Red-green-blue white light-emitting diodes (RGB-WLEDs) have great potential as commercial solid-state lighting devices, as well as visible light communication because of their high color-rendering index (CRI) and high response frequency. The quality of light of an RGB-WLED strongly depends on its spectral parameters. In this study, we fabricated RGB-WLEDs with red, blue, and green LEDs and measured the spectral power distribution (SPD). The experimental SPD is consistent with the calculated spectrum. We also measured the SPDs of LEDs with different peak wavelengths and extracted the spectral parameters, which were then used for modeling. We studied the effect of the wavelength and the full width at half-maximum (FWHM) on both the color rendering index and the luminous efficiency (LE) of the RGB-WLED using simulations. We find that the LE improves as the wavelength of the blue LED increases and the wavelength of the red LED decreases. When the wavelength of the green LED increases, the LE increases first, but later decreases. The CRI of the RGB-WLED increases with the wavelengths of the red, blue, and green LEDs first, but then decreases. The optimal wavelengths and FWHMs for maximum color-rendering and LE of the blue, green, and red LEDs are 466, 536, 606 nm; and 26.0, 34.0, and 19.5 nm, respectively. PMID:27411203

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

    PubMed Central

    Chi, Yu-Chieh; Hsieh, Dan-Hua; Lin, Chung-Yu; Chen, Hsiang-Yu; Huang, Chia-Yen; He, Jr-Hau; Ooi, Boon; DenBaars, Steven P.; Nakamura, Shuji; Kuo, Hao-Chung; Lin, Gong-Ru

    2015-01-01

    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. PMID:26687289

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

    NASA Astrophysics Data System (ADS)

    Chi, Yu-Chieh; Hsieh, Dan-Hua; Lin, Chung-Yu; Chen, Hsiang-Yu; Huang, Chia-Yen; He-Hau, Jr.; Ooi, Boon; Denbaars, Steven P.; Nakamura, Shuji; Kuo, Hao-Chung; Lin, Gong-Ru

    2015-12-01

    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.

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

    PubMed

    Chi, Yu-Chieh; Hsieh, Dan-Hua; Lin, Chung-Yu; Chen, Hsiang-Yu; Huang, Chia-Yen; He, Jr-Hau; Ooi, Boon; DenBaars, Steven P; Nakamura, Shuji; Kuo, Hao-Chung; Lin, Gong-Ru

    2015-01-01

    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 120(o) 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. PMID:26687289

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

    DOEpatents

    Vogl, Otto; Li, Shanjun

    1988-05-17

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

  6. Evidence from studies with acifluorfen for participation of a flavin-cytochrome complex in blue light photoreception for phototropism of oat coleoptiles.

    PubMed

    Leong, T Y; Briggs, W R

    1982-09-01

    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

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

    PubMed Central

    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

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

    PubMed

    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. PMID:26906985

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

    NASA Technical Reports Server (NTRS)

    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.

  10. Computer simulation of PPF distribution under blue and red LED light source for plant growth.

    PubMed

    Takita, S; Okamoto, K; Yanagi, T

    1996-12-01

    The superimposed pattern of "luminescence spectrum of blue light emitting diode (LED)" and "that of red LED", corresponds well to light absorption spectrum of chlorophyll. If these two kinds of LED are used as a light source, various plant cultivation experiments are possible. The cultivation experiments which use such light sources are becoming increasingly active, and in such experiments, it is very important to know the distribution of the photosynthetic photon flux (PPF) which exerts an important influence on photosynthesis. Therefore, we have developed a computer simulation system which can visualize the PPF distribution under a light source equipped with blue and red LEDs. In this system, an LED is assumed to be a point light source, and only the photons which are emitted directly from LED are considered. This simulation system can display a perspective view of the PPF distribution, a transverse and a longitudinal section of the distribution, and a contour map of the distribution. Moreover, a contour map of the ratio of the value of the PPF emitted by blue LEDs to that by blue and red LEDs can be displayed. As the representation is achieved by colored lines according to the magnitudes of the PPF in our system, a user can understand and evaluate the state of the PPF well. PMID:11541576

  11. Analysis of Old Copper Synchrotron Light Absorbers from the Stanford Positron Electron Accelerating Ring

    SciTech Connect

    Marshall, S.R.; Scott, B.; /SLAC

    2005-12-15

    Synchrotron light absorbers intercept synchrotron radiation to protect chamber walls from excessive heat. When subjected to the high temperature of the beam, these absorbers undergo thermal stress. If the stress is too great or fatigues the material, the absorbers may fail. These absorbers are designed to last the lifetime of the machine. Any premature cracking could result in a leak and, consequently, loss of the ultra high vacuum environment. Using secondary and backscattered electron techniques, several sections of a used copper absorber were analyzed for material damage. Chemical analyses were performed on these samples as well. Comparing the unexposed sections to the sections exposed to the electron beam, few cracks were seen in the copper. However, the exposed samples showed heavy surface damage, in addition to crevices that could eventually result in material failure. Significant corrosion was also evident along the water cooling passage of the samples. These findings suggest that further investigation and periodic inspection of absorbers in SPEAR3 are necessary to control corrosion of the copper.

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

    PubMed

    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. PMID:27216620

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

    PubMed Central

    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

    2015-01-01

    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. PMID:26678364

  14. Sustained effects of blue light on Streptococcus mutans in regrown biofilm.

    PubMed

    Cohen-Berneron, Julie; Steinberg, Doron; Featherstone, John D B; Feuerstein, Osnat

    2016-04-01

    In prior studies, exposure of Streptococcus mutans in biofilm to blue light using high fluences of up to 680 J/cm(2) did not interfere with bacterial capability to reform an initial biofilm; however, a delayed antibacterial effect was observed. Our aim was to determine the sustained effecttts of blue light-emitting diode (LED) curing light on the pathogenicity of the newly formed biofilm. S. mutans were grown to form biofilm that was exposed to blue light (wavelengths, 460-480 nm) for 1, 3, and 7 min (equivalent to 37, 112, and 262 J/cm(2), respectively). Then, bacteria were suspended and allowed to regrow into new biofilms. The regrown biofilms were assessed for bacterial quantification by optical density (OD) measurement and quantitative polymerase chain reaction (qPCR), bacterial viability and extracellular polysaccharide production by fluorescent staining using confocal scanning laser microscopy, acid production by bacteria (acidogenicity), and bacterial survival at low pH (aciduricity) using qPCR. Bacterial growth in the regrown biofilms was increased when samples were previously exposed to light; however, under the confocal microscopy, a higher proportion of dead bacteria and a reduction in polysaccharide production were observed. The acidogenicity from the regrown biofilm was lowered as fluences of light increased. The aciduricity of the regrown biofilm was decreased, meaning less growth of bacteria into biofilm in low pH with increasing fluences. Blue light has sustained effects on S. mutans bacteria grown into new biofilm. Although bacterial growth in biofilm increased, bacterial viability and virulence characteristics were impaired. The cariogenic potential over time of S. mutans previously exposed to blue light when grown on tooth surfaces is yet to be determined. PMID:26796707

  15. A synthetic erectile optogenetic stimulator enabling blue-light-inducible penile erection.

    PubMed

    Kim, Taeuk; Folcher, Marc; Doaud-El Baba, Marie; Fussenegger, Martin

    2015-05-11

    Precise spatiotemporal control of physiological processes by optogenetic devices inspired by synthetic biology may provide novel treatment opportunities for gene- and cell-based therapies. An erectile optogenetic stimulator (EROS), a synthetic designer guanylate cyclase producing a blue-light-inducible surge of the second messenger cyclic guanosine monophosphate (cGMP) in mammalian cells, enabled blue-light-dependent penile erection associated with occasional ejaculation after illumination of EROS-transfected corpus cavernosum in male rats. Photostimulated short-circuiting of complex psychological, neural, vascular, and endocrine factors to stimulate penile erection in the absence of sexual arousal may foster novel advances in the treatment of erectile dysfunction. PMID:25788334

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

    NASA Technical Reports Server (NTRS)

    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.

  17. Compound parabolic concentrator design for red, green, blue, and white LED light mixing

    NASA Astrophysics Data System (ADS)

    Wei, An-Chi; Lo, Shih-Chieh; Hung, Pei-Fang; Lee, Ju-Yi; Yeh, Hong-Yih; Huang, Hong-Cheng; Li, Chia-Ming

    2016-08-01

    A light-mixing module consisting of a compound parabolic concentrator (CPC) and a fiber for mixing light from red, green, blue, and white (RGBW) LEDs was proposed. The design principle was investigated and a design prototype was demonstrated in a simulation. The simulated results showed that the chromatic nonuniformity was reduced to 1/10 when the fiber length was 40 times the core width, and the module efficiencies were more than 80% and more than 60% when the fiber lengths were 350 mm and 5 m, respectively. The proposed module is suitable for solar lighting compensation or indoor lighting, such as plant-factory lighting.

  18. High-brightness blue organic light emitting diodes with different types of guest-host systems

    NASA Astrophysics Data System (ADS)

    Wang, Xiao; Zhang, Jing-shuang; Peng, Cui-yun; Guo, Kun-ping; Wei, Bin; Zhang, Hao

    2016-03-01

    We demonstrate high-brightness blue organic light emitting diodes (OLEDs) using two types of guest-host systems. A series of blue OLEDs were fabricated using three organic emitters of dibenz anthracene (perylene), di(4-fluorophenyl) amino-di (styryl) biphenyl (DSB) and 4,4'-bis[2-(9-ethyl-3-carbazolyl)vinyl]biphenyl (BCzVBi) doped into two hosting materials of 4,4'-bis(9-carbazolyl) biphenyl (CBP) and 2-(4-biphenylyl)-5(4-tert-butyl-phenyl)-1,3,4-oxadiazole (PBD) as blue emitting layers, respectively. We achieve three kinds of devices with colors of deep-blue, pure-blue and sky-blue with the Commission Internationale de L'Eclairage (CIE) coordinates of (0.16, 0.10), (0.15, 0.15) and (0.17, 0.24), respectively, by employing PBD as host material. In addition, we present a microcavity device using the PBD guest-host system and achieve high-purity blue devices with narrowed spectrum.

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

    PubMed

    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. PMID:26288067

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

    PubMed

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

    2016-08-19

    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

  1. Experimental Study of Red-, Green-, and Blue-Based Light Emitting Diodes Visible Light Communications for Micro-Projector Application

    NASA Astrophysics Data System (ADS)

    Chou, H.-H.; Liaw, S.-K.; Jiang, J.-S.; Teng, C.

    2016-05-01

    In this research, an experimental short-range visible light communication link using red-, green-, and blue-based light-emitting diodes (LEDs) for portable micro-projector applications is presented. A Reconfigurable design of a post-equalizer aimed to improve the inherent narrow modulation bandwidth of red-, green-, and blue-based LEDs has been experimentally implemented, and its effectiveness with optical filters at the receiver is investigated. Reflective liquid-crystal-on-silicon-based micro-projection architecture, widely used in portable micro-projectors, was set up to evaluate the proposed visible light communication system. The measurement results demonstrated that a significant aggregative bandwidth improvement of 162 MHz as well as an aggregative data transmission rate of nearly 400 Mb/s can be achieved by using a non-return-to-zero-on-off keying (NRZ-OOK) modulation scheme based on only one polarization state of incident light without any offline signal processing.

  2. Viral Inactivation of Human Osteochondral Grafts with Methylene Blue and Light

    PubMed Central

    Zhao, Zhixing; Call, Gazell M.; Gao, Jizong; Yao, Jian Q.

    2014-01-01

    Objective: Cartilage injury is one of the most common disorders of synovial joints. Fresh osteochondral allografts are becoming a standard treatment; however, they are supply constrained with a potential risk of disease transmission. There are no known virucidal processes available for osteochondral allografts and most methods presently available are detrimental to cartilage. Methylene blue light treatment has been shown to be successful in the literature for viral inactivation of fresh frozen plasma. The purpose of this study was to determine the capacity of methylene blue light treatment to inactivate a panel of clinically relevant viruses inoculated onto osteochondral allografts. Design: Osteochondral grafts recovered from human cadaveric knees were inoculated with one of the following viruses: bovine viral diarrhea virus (BVDV), hepatitis A virus (HAV), human immunodeficiency virus type 1 (HIV-1), porcine parvovirus (PPV), and pseudorabies virus (PrV). The samples were processed through a methylene blue light treatment, which consisted of an initial soak in nonilluminated circulating methylene blue at ambient temperature, followed by light exposure with circulating methylene blue at cool temperatures. The final titer was compared with the recovery control for the viral log reduction. Results: HIV-1, BVDV, and PrV were reduced to nondetectable levels while HAV and PPV were reduced by 3.1 and 5.6 logs, respectively. Conclusions: The methylene blue light treatment was effective in reducing (a) enveloped DNA and RNA viruses to nondetectable levels and (b) nonenveloped DNA and RNA viruses of inoculated human osteochondral grafts by 3.1 to 5.6 logs. This study demonstrates the first practical method for significantly reducing viral load in osteochondral implants. PMID:26069682

  3. Light harvesting in photonic crystals revisited: why do slow photons at the blue edge enhance absorption?

    PubMed

    Deparis, O; Mouchet, S R; Su, B-L

    2015-11-11

    Light harvesting enhancement by slow photons in photonic crystal catalysts or dye-sensitized solar cells is a promising approach for increasing the efficiency of photoreactions. This structural effect is exploited in inverse opal TiO2 photocatalysts by tuning the red edge of the photonic band gap to the TiO2 electronic excitation band edge. In spite of many experimental demonstrations, the slow photon effect is not fully understood yet. In particular, observed enhancement by tuning the blue edge has remained unexplained. Based on rigorous couple wave analysis simulations, we quantify light harvesting enhancement in terms of absorption increase at a specific wavelength (monochromatic UV illumination) or photocurrent increase (solar light illumination), with respect to homogeneous flat slab of equivalent material thickness. We show that the commonly accepted explanation relying on light intensity confinement in high (low) dielectric constant regions at the red (blue) edge is challenged in the case of TiO2 inverse opals because of the sub-wavelength size of the material skeleton. The reason why slow photons at the blue edge are also able to enhance light harvesting is the loose confinement of the field, which leads to significant resonantly enhanced field intensity overlap with the skeleton in both red and blue edge tuning cases, yet with different intensity patterns. PMID:26517229

  4. Clinical Efficacy of Blue Light Full Body Irradiation as Treatment Option for Severe Atopic Dermatitis

    PubMed Central

    Becker, Detlef; Seemann, Gunda; Fell, Isabel; Saloga, Joachim; Grabbe, Stephan; von Stebut, Esther

    2011-01-01

    Background Therapy of atopic dermatitis (AD) relies on immunosuppression and/or UV irradiation. Here, we assessed clinical efficacy and histopathological alterations induced by blue light-treatment of AD within an observational, non-interventional study. Methodology/Principal Findings 36 patients with severe, chronic AD resisting long term disease control with local corticosteroids were included. Treatment consisted of one cycle of 5 consecutive blue light-irradiations (28.9 J/cm2). Patients were instructed to ask for treatment upon disease exacerbation despite interval therapy with topical corticosteroids. The majority of patients noted first improvements after 2–3 cycles. The EASI score was improved by 41% and 54% after 3 and 6 months, respectively (p≤0.005, and p≤0.002). Significant improvement of pruritus, sleep and life quality was noted especially after 6 months. Also, frequency and intensity of disease exacerbations and the usage of topical corticosteroids was reduced. Finally, immunohistochemistry of skin biopsies obtained at baseline and after 5 and 15 days revealed that, unlike UV light, blue light-treatment did not induce Langerhans cell or T cell depletion from skin. Conclusions/Significance Blue light-irradiation may represent a suitable treatment option for AD providing long term control of disease. Future studies with larger patient cohorts within a randomized, placebo-controlled clinical trial are required to confirm this observation. PMID:21687679

  5. Fabrication of chalcopyrite light-absorbing layers based on nanoparticle and nanowire networks

    NASA Astrophysics Data System (ADS)

    Ren, Yuhang; Luo, Paifeng; Gao, Bo; Cevher, Zehra; Sun, Chivin

    2013-03-01

    We report on a method of preparing chalcopyrite, CuInGaSe2 (CIGS) light-absorbing layers using low cost air stable ink based on semiconductor nanoparticle and nanowires. The nanoparticles and nanowires are prepared from metal salts such as metal chloride and acetate at room temperature without inert gas protection. A uniform and non-aggregation CIGS precursor layer is fabricated with the formation of nanoparticle and nanowire networks utilizing ultrasonic spaying technique. We obtain a high quality CIGS absorber by cleaning the residue salts and carbon agents at an increased temperature and through selenizing the pretreated CIGS precursors. Our results offer an opportunity for the low-cost deposition of chalcopyrite absorber materials at large scale with high throughput. This work was partially sponsored by Sun Harmonics Ltd. and by NYSTAR through the Photonics Center for Applied Technology at the City University of New York.

  6. Photothermally tunable silicon-microring-based optical add-drop filter through integrated light absorber.

    PubMed

    Chen, Xi; Shi, Yuechun; Lou, Fei; Chen, Yiting; Yan, Min; Wosinski, Lech; Qiu, Min

    2014-10-20

    An optically pumped thermo-optic (TO) silicon ring add-drop filter with fast thermal response is experimentally demonstrated. We propose that metal-insulator-metal (MIM) light absorber can be integrated into silicon TO devices, acting as a localized heat source which can be activated remotely by a pump beam. The MIM absorber design introduces less thermal capacity to the device, compared to conventional electrically-driven approaches. Experimentally, the absorber-integrated add-drop filter shows an optical response time of 13.7 μs following the 10%-90% rule (equivalent to a exponential time constant of 5 μs) and a wavelength shift over pump power of 60 pm/mW. The photothermally tunable add-drop filter may provide new perspectives for all-optical routing and switching in integrated Si photonic circuits. PMID:25401557

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

    NASA Astrophysics Data System (ADS)

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

    2010-04-01

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

  8. Effect of blue/red LED light combination on growth and morphogenesis of saccharum officinarum plantlets in vitro

    NASA Astrophysics Data System (ADS)

    Silva, Marina M. A.; de Oliveira, Arquimedes L. B.; Oliveira-Filho, Ronaldo A.; Gouveia-Neto, Artur S.; Camara, Terezinha J. R.; Willadino, Lilia G.

    2014-03-01

    The effect of blue and red light mixture and white-light (RGB) from monochromatic light-emitting diodes on growth and morphogenesis of sugarcane (Saccharum officinarum) plantlets in vitro, was investigated. Light treatments with blue/red light intensity percentage ratio 70/30, 50/50, 40/60, 30/70, and also white-LED light were applied during a period of 20 days with a photoperiod of 16 h per day. Results indicate that the blue/red light blend ratio of the illumination system plays a major role in fresh weight, length, and shoot multiplication of plantlets cultured in vitro. White-light via blended primary colors monochromatic LEDs illumination of the plantlets culture was also evaluated and compared with blue/red lighting

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

    NASA Astrophysics Data System (ADS)

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

    2015-02-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2014-10-01

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

  11. A Blue-Light-Emitting BODIPY Probe for Lipid Membranes.

    PubMed

    Bacalum, Mihaela; Wang, Lina; Boodts, Stijn; Yuan, Peijia; Leen, Volker; Smisdom, Nick; Fron, Eduard; Knippenberg, Stefan; Fabre, Gabin; Trouillas, Patrick; Beljonne, David; Dehaen, Wim; Boens, Noël; Ameloot, Marcel

    2016-04-12

    Here we describe a new BODIPY-based membrane probe (1) that provides an alternative to dialkylcarbocyanine dyes, such as DiI-C18, that can be excited in the blue spectral region. Compound 1 has unbranched octadecyl chains at the 3,5-positions and a meso-amino function. In organic solvents, the absorption and emission maxima of 1 are determined mainly by solvent acidity and dipolarity. The fluorescence quantum yield is high and reaches 0.93 in 2-propanol. The fluorescence decays are well fitted with a single-exponential in pure solvents and in small and giant unilamellar vesicles (GUV) with a lifetime of ca. 4 ns. Probe 1 partitions in the same lipid phase as DiI-C18(5) for lipid mixtures containing sphingomyelin and for binary mixtures of dipalmitoylphosphatidylcholine (DPPC) and dioleoylphosphatidylcholine (DOPC). The lipid phase has no effect on the fluorescence lifetime but influences the fluorescence anisotropy. The translational diffusion coefficients of 1 in GUVs and OLN-93 cells are of the same order as those reported for DiI-C18. The directions of the absorption and emission transition dipole moments of 1 are calculated to be parallel. This is reflected in the high steady-state fluorescence anisotropy of 1 in high ordered lipid phases. Molecular dynamic simulations of 1 in a model of the DOPC bilayer indicate that the average angle of the transition moments with respect to membrane normal is ca. 70°, which is comparable with the value reported for DiI-C18. PMID:27003513

  12. Supplemental Blue LED Lighting Array to Improve the Signal Quality in Hyperspectral Imaging of Plants

    PubMed Central

    Mahlein, Anne-Katrin; Hammersley, Simon; Oerke, Erich-Christian; Dehne, Heinz-Wilhelm; Goldbach, Heiner; Grieve, Bruce

    2015-01-01

    Hyperspectral imaging systems used in plant science or agriculture often have suboptimal signal-to-noise ratio in the blue region (400–500 nm) of the electromagnetic spectrum. Typically there are two principal reasons for this effect, the low sensitivity of the imaging sensor and the low amount of light available from the illuminating source. In plant science, the blue region contains relevant information about the physiology and the health status of a plant. We report on the improvement in sensitivity of a hyperspectral imaging system in the blue region of the spectrum by using supplemental illumination provided by an array of high brightness light emitting diodes (LEDs) with an emission peak at 470 nm. PMID:26039423

  13. A modern perspective on the history of semiconductor nitride blue light sources

    NASA Astrophysics Data System (ADS)

    Maruska, Herbert Paul; Rhines, Walden Clark

    2015-09-01

    In this paper we shall discuss the development of blue light-emitting (LED) and laser diodes (LD), starting early in the 20th century. Various materials systems were investigated, but in the end, the nitrides of aluminum, gallium and indium proved to be the most effective. Single crystal thin films of GaN first emerged in 1968. Blue light-emitting diodes were first reported in 1971. Devices grown in the 1970s were prepared by the halide transport method, and were never efficient enough for commercial products due to contamination. Devices created by metal-organic vapor-phase epitaxy gave far superior performance. Actual true blue LEDs based on direct band-to-band transitions, free of recombination through deep levels, were finally developed in 1994, leading to a breakthrough in LED performance, as well as nitride based laser diodes in 1996. In 2014, the scientists who achieved these critical results were awarded the Nobel Prize in Physics.

  14. Supplemental blue LED lighting array to improve the signal quality in hyperspectral imaging of plants.

    PubMed

    Mahlein, Anne-Katrin; Hammersley, Simon; Oerke, Erich-Christian; Dehne, Heinz-Wilhelm; Goldbach, Heiner; Grieve, Bruce

    2015-01-01

    Hyperspectral imaging systems used in plant science or agriculture often have suboptimal signal-to-noise ratio in the blue region (400-500 nm) of the electromagnetic spectrum. Typically there are two principal reasons for this effect, the low sensitivity of the imaging sensor and the low amount of light available from the illuminating source. In plant science, the blue region contains relevant information about the physiology and the health status of a plant. We report on the improvement in sensitivity of a hyperspectral imaging system in the blue region of the spectrum by using supplemental illumination provided by an array of high brightness light emitting diodes (LEDs) with an emission peak at 470 nm. PMID:26039423

  15. Acute exposure to evening blue-enriched light impacts on human sleep.

    PubMed

    Chellappa, Sarah L; Steiner, Roland; Oelhafen, Peter; Lang, Dieter; Götz, Thomas; Krebs, Julia; Cajochen, Christian

    2013-10-01

    Light in the short wavelength range (blue light: 446-483 nm) elicits direct effects on human melatonin secretion, alertness and cognitive performance via non-image-forming photoreceptors. However, the impact of blue-enriched polychromatic light on human sleep architecture and sleep electroencephalographic activity remains fairly unknown. In this study we investigated sleep structure and sleep electroencephalographic characteristics of 30 healthy young participants (16 men, 14 women; age range 20-31 years) following 2 h of evening light exposure to polychromatic light at 6500 K, 2500 K and 3000 K. Sleep structure across the first three non-rapid eye movement non-rapid eye movement - rapid eye movement sleep cycles did not differ significantly with respect to the light conditions. All-night non-rapid eye movement sleep electroencephalographic power density indicated that exposure to light at 6500 K resulted in a tendency for less frontal non-rapid eye movement electroencephalographic power density, compared to light at 2500 K and 3000 K. The dynamics of non-rapid eye movement electroencephalographic slow wave activity (2.0-4.0 Hz), a functional index of homeostatic sleep pressure, were such that slow wave activity was reduced significantly during the first sleep cycle after light at 6500 K compared to light at 2500 K and 3000 K, particularly in the frontal derivation. Our data suggest that exposure to blue-enriched polychromatic light at relatively low room light levels impacts upon homeostatic sleep regulation, as indexed by reduction in frontal slow wave activity during the first non-rapid eye movement episode. PMID:23509952

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

    EPA Science Inventory

    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...

  17. Photomanipulation of vasodilation with a blue-light-controllable nitric oxide releaser.

    PubMed

    Ieda, Naoya; Hotta, Yuji; Miyata, Naoki; Kimura, Kazunori; Nakagawa, Hidehiko

    2014-05-14

    Spatiotemporally controllable nitric oxide (NO)-releasers allow us to analyze the physiological effects of NO, a gaseous mediator that modulates many biological signaling networks, and are also candidate chemotherapeutic agents. We designed and synthesized a blue-light-controllable NO releaser, named NOBL-1, which bears an N-nitrosoaminophenol moiety for NO release tethered to a BODIPY dye moiety for harvesting blue light. Photoinduced electron transfer from N-nitrosoaniline to the antenna moiety upon irradiation with relatively noncytotoxic blue light (470-500 nm) should result in NO release with formation of a stable quinone moiety. NO release from NOBL-1 was confirmed by ESR spin trapping and fluorescence detection. Spatially controlled NO release in cells was observed with DAR-4M AM, a fluorogenic NO probe. We also demonstrated temporally controlled vasodilation of rat aorta ex vivo by blue-light-induced NO release from NOBL-1. This compound should be useful for precise examination of the functions of NO with excellent spatiotemporal control. PMID:24731151

  18. Effects of blue light phototherapy on DNA integrity in preterm newborns.

    PubMed

    Gómez-Meda, Belinda C; Barros-Hernández, Angélica; Guzmán-Bárcenas, José; Lemus-Varela, María de Lourdes; Zamora-Perez, Ana L; Torres-Mendoza, Blanca M; Gallegos-Arreola, Martha P; Armendáriz-Borunda, Juan; Zúñiga-González, Guillermo M

    2014-12-01

    In previous studies, exposure to phototherapy, but not oxygen therapy, resulted in damage to genetic material in newborns. The objective of this study was to determine whether micronucleated erythrocytes (MNE) increased in preterm newborns (PNBs) who were exposed to blue light phototherapy lamps. MNE of mature organisms are rapidly eliminated by the spleen, and the presence of MNE has been related to immaturity in some species. Furthermore, PNBs present spontaneous MNE. Blood samples were taken from 17 PNBs at birth to establish baseline frequencies (0 h). After beginning blue light phototherapy, blood samples were obtained from 11 of these PNBs at 24-h intervals for 96 h, after the baseline sample. MNE and micronucleated polychromatic erythrocytes (MNPCE) were counted. The basal values of MNE and MNPCE from 17 PNBs were 0.62 ± 0.48 and 1.52 ± 1.28 (‰), respectively, and no increase in MNE or MNPCE was observed in the serial samples of 11 PNBs exposed to blue light and oxygen therapies, though previous studies reported increases using other types of lamps. In conclusion, under the conditions described no increase in the number of MNE or MNPCE was observed in the peripheral blood of PNBs exposed to blue light phototherapy. PMID:25463679

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

    PubMed

    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. PMID:26432407

  20. An extraretinally expressed insect cryptochrome with similarity to the blue light photoreceptors of mammals and plants.

    PubMed

    Egan, E S; Franklin, T M; Hilderbrand-Chae, M J; McNeil, G P; Roberts, M A; Schroeder, A J; Zhang, X; Jackson, F R

    1999-05-15

    Photic entrainment of insect circadian rhythms can occur through either extraretinal (brain) or retinal photoreceptors, which mediate sensitivity to blue light or longer wavelengths, respectively. Although visual transduction processes are well understood in the insect retina, almost nothing is known about the extraretinal blue light photoreceptor of insects. We now have identified and characterized a candidate blue light photoreceptor gene in Drosophila (DCry) that is homologous to the cryptochrome (Cry) genes of mammals and plants. The DCry gene is located in region 91F of the third chromosome, an interval that does not contain other genes required for circadian rhythmicity. The protein encoded by DCry is approximately 50% identical to the CRY1 and CRY2 proteins recently discovered in mammalian species. As expected for an extraretinal photoreceptor mediating circadian entrainment, DCry mRNA is expressed within the adult brain and can be detected within body tissues. Indeed, tissue in situ hybridization demonstrates prominent expression in cells of the lateral brain, which are close to or coincident with the Drosophila clock neurons. Interestingly, DCry mRNA abundance oscillates in a circadian manner in Drosophila head RNA extracts, and the temporal phasing of the rhythm is similar to that documented for the mouse Cry1 mRNA, which is expressed in clock tissues. Finally, we show that changes in DCry gene dosage are associated predictably with alterations of the blue light resetting response for the circadian rhythm of adult locomotor activity. PMID:10233998

  1. RNA-Seq reveals changes in the Staphylococcus aureus transcriptome following blue light illumination.

    PubMed

    Adair, Tamarah L; Drum, Bayless E

    2016-09-01

    In an effort to better understand the mechanism by which blue light inhibits the growth of Staphylococcus aureus in culture, a whole transcriptome analysis of S. aureus isolate BUSA2288 was performed using RNA-Seq to analyze the differential gene expression in response to blue light exposure. RNA was extracted from S. aureus cultures pooled from 24 1 ml well samples that were each illuminated with a dose of 250 J/cm(2) of 465 nm blue light and from control cultures grown in the dark. Complementary DNA libraries were generated from enriched mRNA samples and sequenced using the Illumina MiSeq Next Generation Sequencer. Here we report one type of analysis that identified 32 candidate genes for further investigation. Blue light has been shown to be bactericidal against S. aureus and is a potential alternative therapy for antibiotic resistant organisms. The mechanism for the inactivation of bacteria is hypothesized to involve reactive oxygen species. These RNA-Seq results provide data that may be used to test this hypothesis. The RNA-Seq data generated by these experiments is deposited in Gene Expression Omnibus (Gene accession GSE62055) and may be found at NCBI (http://www.ncbi.nlm.nih.gov/geo/query/acc.cgi?acc=GSE62055). PMID:27330994

  2. High-precision measurements of light-induced torque on absorbing microspheres

    NASA Astrophysics Data System (ADS)

    Capitanio, Marco; Normanno, Davide; Saverio Pavone, Francesco

    2004-10-01

    Laser beams have been demonstrated to be capable of exerting torque as well as forces on microparticles. Using a custom magneto-optic manipulator, we directly measured the torque exerted by laser light on absorbing microspheres as a result of the transfer of spin angular momentum. A general method for measuring torque has been developed, and the experimental apparatus has shown a sensitivity of ~1 pN/nm.

  3. Comparison of Absorbents and Drugs for Internal Decorporation of Radiocesium: Advances of Polyvinyl Alcohol Hydrogel Microsphere Preparations Containing Magnetite and Prussian Blue.

    PubMed

    Tanaka, Izumi; Ishihara, Hiroshi; Yakumaru, Haruko; Tanaka, Mika; Yokochi, Kazuko; Tajima, Katsushi; Akashi, Makoto

    2016-01-01

    Radiocesium nuclides, used as a gamma ray source in various types of industrial equipments and found in nuclear waste, are strictly controlled to avoid their leakage into the environment. When large amounts of radiocesium are accidentally incorporated into the human body, decorporation therapy should be considered. Although standard decorporation methods have been studied since the 1960s and were established in the 1970s with the drug Radiogardase(®) (a Prussian blue preparation), application of recent advances in pharmacokinetics and ethical standards could improve these methods. Here we designed a modern dosage form of hydrogel containing cesium-absorbents to alleviate intestinal mucosa irritation due to the cesium-binding capacity of the absorbents. The effectiveness of the dosage form on fecal excretion was confirmed by quantitative mouse experiments. The total cesium excretion rate of the crystal form (1.37±0.09) was improved by the hydrogel form (1.52±0.10) at the same dose of Prussian blue, with a longer gastrointestinal tract transit time. Using a mouse model, we compared the effects of several drugs on fecal and urinary excretion of internal cesium, without the use of absorbents. Only phenylephrine hydrochloride significantly enhanced cesium excretion (excretion rate of 1.17±0.08) via the urinary pathway, whereas none of the diuretic drugs tested had this effect. These findings indicate that modifying the dosage form of cesium absorbents is important for the decorporation of internal radiocesium contamination. PMID:26725529

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

    PubMed

    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. PMID:23393888

  5. Response of the Sensory animal-like cryptochrome aCRY to blue and red light as revealed by infrared difference spectroscopy.

    PubMed

    Spexard, Meike; Thöing, Christian; Beel, Benedikt; Mittag, Maria; Kottke, Tilman

    2014-02-18

    Cryptochromes act as blue light sensors in plants, insects, fungi, and bacteria. Recently, an animal-like cryptochrome (aCRY) was identified in the green alga Chlamydomonas reinhardtii by which gene expression is altered in response to not only blue light but also yellow and red light. This unique response of a flavoprotein in vivo has been attributed to the fact that the neutral radical of the flavin chromophore acts as dark form of the sensor, which absorbs in almost the entire visible spectral range (<680 nm). Here, we investigated light-induced processes in the protein moiety of full-length aCRY by UV-vis and Fourier transform infrared spectroscopy. Findings are compared to published results on the homologous (6-4) photolyases, DNA repair enzymes. The oxidized state of aCRY is converted to the neutral radical by blue light. The recovery is strongly dependent on pH and might be catalyzed by a conserved histidine of the (6-4)/clock cluster. The decay is independent of oxygen concentration in contrast to that of other cryptochromes and (6-4) photolyases. This blue light reaction of the oxidized flavin is not accompanied by any detectable changes in secondary structure, in agreement with a role in vivo of an unphysiological preactivation. In contrast, the conversion by red light of the neutral radical to the anionic fully reduced state proceeds with conformational changes in turn elements, which most probably constitute a part of the signaling process. These changes have not been detected in the corresponding transition of (6-4) photolyase, which points to a decisive difference between the sensor and the enzyme. PMID:24467183

  6. Blue/white organic light-emitting diodes and passive matrix display

    NASA Astrophysics Data System (ADS)

    Zhang, Zhi-Lin; Jiang, Xue-Yin; Zhu, Wen-Qing; Xu, Shao-Hong

    2005-01-01

    The blue organic light emitting diodes (OLED) based on anthracene derivatives (ADN) doped with distryrylarylene derivatives (BCzVB and DSA-ph) were presented. The device of ADN doped with BCzVb shows high color purity (x=0.146, y=0.162) with maximum luminance 11600 cd/m2 (15V), current efficiency 2.8 cd/A, while the device of ADN doped with DSA-ph exhibits a sky blue with as high as efficiency 8.29 cd/A, both have a flat efficiency vs current density responses. A typical blue device of ADN doped with TBPe is used for comparison, which gives greenish blue and a stronger current-induced flyorescence quenching. Three kinds of White organic light emitting devices (WOLED) with different dopants and doping sites were constructed. The cell with a single-doped red dye in the light emitting layer (EML)(single-doped) and the cell with both red and blue dyes doped in a single EML (double-doped as well as the cell with red and blue dyes doped in EML and a green dye in another layer (triple-doped). The triple-doped cell shows much higher performance than other two cells: maximum luminance 21200cd/m2, 1026 cd/m2 at driving current 20mA/cm2, efficiency 6cd/A and a half lifetime over 22245h were reached. A passive display features 102x64 pixels with pixel size of 0.25x0.25mm2 pixel pitch 0.08mm, luminance 100 cd/m2 at driving duty 1/64, and power consumption of 0.6W was constructed.

  7. High luminance low etendue white light source using blue laser over static phosphor

    NASA Astrophysics Data System (ADS)

    Farooq, Tayyab; Qian, KeYuan

    2015-10-01

    A High Luminance White Light source for Etendue limited application has been demonstrated in this research paper by using blue InGaN laser diode beam over static source of phosphor Ce: YAG layer. Phosphor target has kept static because moving phosphor target light output is not constant and uniform. Different color temperatures had been obtained by varying phosphor concentration and thickness of the layer. When laser beam has focused on phosphor target spot, it induced very high temperature at that spot area. Temperature induced in the layer by laser beam depends on the layer thickness. All the layer thickness, surface temperature, output light flux, efficiency, and light color temperature are interrelate with each other. Uniform laser beam distribution, surface temperature, laser spot size, phosphor layer thickness are successfully calculated. Luminous efficiency, light color temperature, flux, wavelength spectrum, and light output power of laser driven white light source had been successfully observed at different laser beam powers.

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

    PubMed

    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

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

    PubMed Central

    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. Polymer-stabilized blue-phase liquid crystal grating cured with interfered visible light.

    PubMed

    Yuan, Yachao; Li, Yan; Chen, Chao Ping; Liu, Shuxin; Rong, Na; Li, Weihuan; Li, Xiao; Zhou, Pengcheng; Lu, Jiangang; Liu, Ruili; Su, Yikai

    2015-07-27

    In this paper, we demonstrate a holographic polymer-stabilized blue-phase liquid crystal grating fabricated using a visible laser. As blue phase is stabilized by the interfered light, polymer-concentration gradient is achieved simultaneously. With the application of a uniform vertical electric field, periodic index distribution is obtained due to polymer-concentration gradient. The grating exhibits several attractive features such as polarization-independency, a broad temperature range, sub-millisecond response, simple fabrication, and low cost, thus holding great potential for photonics applications. PMID:26367659

  11. Active differential optical absorption spectroscopy for NO2 gas pollution using blue light emitting diodes

    NASA Astrophysics Data System (ADS)

    Aljalal, Abdulaziz; Gasmi, Khaled; Al-Basheer, Watheq

    2015-05-01

    Availability of high intensity light emitting diodes in the blue region offer excellent opportunity for using them in active Differential Optical Absorption Spectroscopy (DOAS) to detect air pollution. Their smooth and relatively broad spectral emissions as well as their long life make them almost ideal light sources for active DOAS. In this study, we report the usage of a blue light emitting diode in an active DOAS setup to measure traces of NO2 gas and achieving few parts per billion detection limit for a path length of 300 m. Details of the setup will be presented along with the effects on measurement accuracy due to shifts in the measured spectra calibration and due to using theoretical instrument Gaussian function instead of the measured instrument function.

  12. High-efficiency blue light generation at 426 nm in low pump regime

    NASA Astrophysics Data System (ADS)

    Tian, Jianfeng; Yang, Chen; Xue, Jia; Zhang, Yuchi; Li, Gang; Zhang, Tiancai

    2016-05-01

    We report high-efficiency Ti:sapphire-laser-based frequency doubling at the cesium D2 line 852 nm using a 20 mm-long periodically-poled potassium titanyl phosphate crystal in a bow-tie four-mirror ring enhancement cavity. The relatively complete cavity design procedure is presented. Focusing that is over twice as loose as optimal focusing is used, and both the fundamental frequency wave and second harmonic beam absorption-induced thermal lensing effects are weakened. Blue light of 210 mW at 426 nm, where absorption is severe, was obtained with 310 mW mode-matched fundamental light, corresponding to conversion efficiency of up to 67%. The blue light beam power showed 1.5% RMS fluctuation over 40 min.

  13. Visualizing the relevance of bacterial blue- and red-light receptors during plant-pathogen interaction.

    PubMed

    Ricci, Ada; Dramis, Lucia; Shah, Rashmi; Gärtner, Wolfgang; Losi, Aba

    2015-10-01

    The foliar pathogen Pseudomonas syringae pv. tomato DC3000 (Pst) leads to consistent losses in tomato crops, urging to multiply investigations on the physiological bases for its infectiveness. As other P. syringae pathovars, Pst is equipped with photoreceptors for blue and red light, mimicking the photosensing ability of host plants. In this work we have investigated Pst strains lacking the genes for a blue-light sensing protein (PstLOV), for a bacteriophytochrome (PstBph1) or for heme-oxygenase-1. When grown in culturing medium, all deletion mutants presented a larger growth than wild-type (WT) Pst under all other light conditions, with the exception of blue light which, under our experimental conditions (photon fluence rate = 40 μmol m(-2) s(-1)), completely suppressed the growth of the deletion mutants. Each of the knockout mutants shows stronger virulence towards Arabidopsis thaliana than PstWT, as evidenced by macroscopic damages in the host tissues of infected leaves. Mutated bacteria were also identified in districts distant from the infection site using scanning electron microscopy. These results underscore the importance of Pst photoreceptors in responding to environmental light inputs and the partial protective role that they exert towards host plants during infection, diminishing virulence and invasiveness. PMID:26147514

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

    NASA Astrophysics Data System (ADS)

    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.

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

    PubMed Central

    Wang, Ying; Ding, Jia-tong; Yang, Hai-ming; Yan, Zheng-jie; Cao, Wei; Li, Yang-bai

    2015-01-01

    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. PMID:26599806

  16. Optical Control of Protein–Protein Interactions via Blue Light-Induced Domain Swapping

    PubMed Central

    2015-01-01

    The design of new optogenetic tools for controlling protein function would be facilitated by the development of protein scaffolds that undergo large, well-defined structural changes upon exposure to light. Domain swapping, a process in which a structural element of a monomeric protein is replaced by the same element of another copy of the same protein, leads to a well-defined change in protein structure. We observe domain swapping in a variant of the blue light photoreceptor photoactive yellow protein in which a surface loop is replaced by a well-characterized protein–protein interaction motif, the E-helix. In the domain-swapped dimer, the E-helix sequence specifically binds a partner K-helix sequence, whereas in the monomeric form of the protein, the E-helix sequence is unable to fold into a binding-competent conformation and no interaction with the K-helix is seen. Blue light irradiation decreases the extent of domain swapping (from Kd = 10 μM to Kd = 300 μM) and dramatically enhances the rate, from weeks to <1 min. Blue light-induced domain swapping thus provides a novel mechanism for controlling of protein–protein interactions in which light alters both the stability and the kinetic accessibility of binding-competent states. PMID:25003701

  17. Does pupil constriction under blue and green monochromatic light exposure change with age?

    PubMed

    Daneault, Véronique; Vandewalle, Gilles; Hébert, Marc; Teikari, Petteri; Mure, Ludovic S; Doyon, Julien; Gronfier, Claude; Cooper, Howard M; Dumont, Marie; Carrier, Julie

    2012-06-01

    Many nonvisual functions are regulated by light through a photoreceptive system involving melanopsin-expressing retinal ganglion cells that are maximally sensitive to blue light. Several studies have suggested that the ability of light to modulate circadian entrainment and to induce acute effects on melatonin secretion, subjective alertness, and gene expression decreases during aging, particularly for blue light. This could contribute to the documented changes in sleep and circadian regulatory processes with aging. However, age-related modification in the impact of light on steady-state pupil constriction, which regulates the amount of light reaching the retina, is not demonstrated. We measured pupil size in 16 young (22.8±4 years) and 14 older (61±4.4 years) healthy subjects during 45-second exposures to blue (480 nm) and green (550 nm) monochromatic lights at low (7×10(12) photons/cm2/s), medium (3×10(13) photons/cm2/s), and high (10(14) photons/cm2/s) irradiance levels. Results showed that young subjects had consistently larger pupils than older subjects for dark adaptation and during all light exposures. Steady-state pupil constriction was greater under blue than green light exposure in both age groups and increased with increasing irradiance. Surprisingly, when expressed in relation to baseline pupil size, no significant age-related differences were observed in pupil constriction. The observed reduction in pupil size in older individuals, both in darkness and during light exposure, may reduce retinal illumination and consequently affect nonvisual responses to light. The absence of a significant difference between age groups for relative steady-state pupil constriction suggests that other factors such as tonic, sympathetic control of pupil dilation, rather than light sensitivity per se, account for the observed age difference in pupil size regulation. Compared to other nonvisual functions, the light sensitivity of steady-state pupil constriction appears to

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

    PubMed Central

    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 < 0.0001). Histological analyses and terminal deoxynucleotidyltransferase-mediated dUTP-biotin nick end labeling (TUNEL) assays indicated no significant damage in the mouse skin exposed to 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 < 0.0001). In conclusion, blue light therapy might offer an effective and safe alternative to conventional antimicrobial therapy for P. aeruginosa burn infections. PMID:23262998

  19. Blue light rescues mice from potentially fatal Pseudomonas aeruginosa burn infection: efficacy, safety, and mechanism of action.

    PubMed

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

    2013-03-01

    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/cm(2), 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 < 0.0001). Histological analyses and terminal deoxynucleotidyltransferase-mediated dUTP-biotin nick end labeling (TUNEL) assays indicated no significant damage in the mouse skin exposed to 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 < 0.0001). In conclusion, blue light therapy might offer an effective and safe alternative to conventional antimicrobial therapy for P. aeruginosa burn infections. PMID:23262998

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

    NASA Technical Reports Server (NTRS)

    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.

  1. Impairment of extramitochondrial oxidative phosphorylation in mouse rod outer segments by blue light irradiation.

    PubMed

    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. PMID:27059514

  2. KillerOrange, a Genetically Encoded Photosensitizer Activated by Blue and Green Light

    PubMed Central

    Bozhanova, Nina G.; Sharonov, George V.; Staroverov, Dmitriy B.; Egorov, Evgeny S.; Ryabova, Anastasia V.; Solntsev, Kyril M.; Mishin, Alexander S.; Lukyanov, Konstantin A.

    2015-01-01

    Genetically encoded photosensitizers, proteins that produce reactive oxygen species when illuminated with visible light, are increasingly used as optogenetic tools. Their applications range from ablation of specific cell populations to precise optical inactivation of cellular proteins. Here, we report an orange mutant of red fluorescent protein KillerRed that becomes toxic when illuminated with blue or green light. This new protein, KillerOrange, carries a tryptophan-based chromophore that is novel for photosensitizers. We show that KillerOrange can be used simultaneously and independently from KillerRed in both bacterial and mammalian cells offering chromatic orthogonality for light-activated toxicity. PMID:26679300

  3. Characteristics of blue organic light emitting diodes with different thick emitting layers

    NASA Astrophysics Data System (ADS)

    Li, Chong; Tsuboi, Taiju; Huang, Wei

    2014-08-01

    We fabricated blue organic light emitting diodes (called blue OLEDs) with emitting layer (EML) of diphenylanthracene derivative 9,10-di(2-naphthyl)anthracene (ADN) doped with blue-emitting DSA-ph (1-4-di-[4-(N,N-di-phenyl)amino]styryl-benzene) to investigate how the thickness of EML and hole injection layer (HIL) influences the electroluminescence characteristics. The driving voltage was observed to increase with increasing EML thickness from 15 nm to 70 nm. The maximum external quantum efficiency of 6.2% and the maximum current efficiency of 14 cd/A were obtained from the OLED with 35 nm thick EML and 75 nm thick HIL. High luminance of 120,000 cd/m2 was obtained at 7.5 V from OLED with 15 nm thick EML.

  4. Improved blue light-emitting polymeric device by the tuning of drift mobility and charge balance

    NASA Astrophysics Data System (ADS)

    Chin, Byung Doo; Suh, Min Chul; Lee, Seong Taek; Chung, Ho Kyoon; Lee, Chang Hee

    2004-03-01

    We have prepared blue polymer-small molecule hybrid electroluminescence devices with improved efficiency and lower driving voltage by the statistical design method. Analysis of time-of-flight measurement shows that amorphous small molecule hole-transporter blended with a blue light-emitting polymer increases the field-dependent hole mobility, with transition from nondispersive to dispersive transport induced by the charge-trapping effect. Moreover, at the electroluminescent devices with different electron injection/transport layer (LiF/Al, LiF/Ca/Al, and Alq3/LiF/Al), efficiency was further increased. We have analyzed that carrier mobility of a multilayered device can also be controlled by the change of electron injection and transport layers. We find that structural design and matching overall charge balance is an essential factor to improve both the operating voltage and efficiency of existing blue polymer devices.

  5. Photodynamic action on microorganisms using iron oxide Fe2O3 nanoparticles and LED blue (405 nm) light

    NASA Astrophysics Data System (ADS)

    Petrov, Pavel O.; Kulikova, Maria V.; Tuchina, Elena S.; Kochubey, Vyacheslav I.; Tuchin, Valery V.

    2012-03-01

    The main goal was to study the sensitivity of microorganisms to combined action of LED blue (405 nm) light and Fe2O3 nanoparticles. The bacterial strains used in this study were Staphylococcus aureus 209 P, S. simulans, Dermabacter hominis (isolated from maxillary sinusitis). As blue light source LED with spectrum maxima at 405 nm was taken. The light exposure was ranged from 5 to 30 min. Fe2O3 nanoparticles with average size about 8 nm in concentration of 0.001% were used. It was shown that irradiation with blue light caused 20 to 90% decrease in the number of microorganisms treated with nanoparticles.

  6. Regulation of Early Light-Inducible Protein Gene Expression by Blue and Red Light in Etiolated Seedlings Involves Nuclear and Plastid Factors.

    PubMed Central

    Adamska, I.

    1995-01-01

    Early light-inducible proteins (ELIPs) are nuclear-encoded chloroplast proteins whose genes are transiently transcribed during the greening process of etiolated plants. In the present work the regulation of ELIP gene expression by blue and red light has been investigated in plumulas of etiolated pea plants (Pisum sativum). The results show that the steady-state level of ELIP transcripts is controlled by a combined action of phytochrome and blue light receptor systems and, in addition, depends on the age of the seedlings. Both a low-light fluence system of blue and a very-low-fluence system of red light are involved in ELIP induction. The threshold for accumulation of ELIP transcripts was as low as 10-5 [mu]E m-2 s-1 for both light qualities but a different pattern of accumulation was obtained in blue and in red light. Blue light not only acts at the level of transcription but also regulates the stability of the ELIP transcripts in a light intensity-dependent manner. Moreover, it is shown that product(s) of nuclear gene(s) negatively regulate the steady-state level of ELIP transcripts during the 1st h of illumination with red light. Preillumination of seedlings with white light abolishes this repression. Accumulation of ELIP transcripts requires "plastid factors" in both blue and red light qualities. PMID:12228423

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

    NASA Technical Reports Server (NTRS)

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

    1990-01-01

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

  8. Surface-active and Light-absorbing Secondary Organic Aerosol (SOA) Material

    NASA Astrophysics Data System (ADS)

    McNeill, V. F.; Sareen, N.; Schwier, A. N.; Shapiro, E. L.

    2009-12-01

    We have observed the formation of light-absorbing, high-molecular-weight, and surface-active organics from methylgyloxal interacting with ammonium salts in aqueous aerosol mimics. Mixtures of methylglyoxal and glyoxal also form light-absorbing products and exhibit surface tension depression with a Langmuir-like dependence on initial methylglyoxal concentration. We used chemical ionization mass spectrometry with a volatilization flow tube inlet (Aerosol-CIMS) to characterize the product species. The results are consistent with aldol condensation products, carbon-nitrogen species, sulfur-containing compounds, and oligomeric species up to 759 amu. These observations have potentially significant implications for our understanding of the effects of SOA on climate, since a) SOA are typically treated as non-absorbing in climate models, and b) surface tension depression in aqueous aerosols by SOA material may result in increased cloud condensation nucleus (CCN) activity. Furthermore, surface film formation could affect aerosol heterogeneous chemistry. We will also discuss aerosol flow tube O3 oxidation experiments designed to determine the atmospheric lifetimes of the observed product compounds.

  9. Individual Differences in the Post-Illumination Pupil Response to Blue Light: Assessment without Mydriatics.

    PubMed

    Bruijel, Jessica; van der Meijden, Wisse P; Bijlenga, Denise; Dorani, Farangis; Coppens, Joris E; Te Lindert, Bart H W; Kooij, J J Sandra; Van Someren, Eus J W

    2016-01-01

    Melanopsin-containing retinal ganglion cells play an important role in the non-image forming effects of light, through their direct projections on brain circuits involved in circadian rhythms, mood and alertness. Individual differences in the functionality of the melanopsin-signaling circuitry can be reliably quantified using the maximum post-illumination pupil response (PIPR) after blue light. Previous protocols for acquiring PIPR relied on the use of mydriatics to dilate the light-exposed eye. However, pharmacological pupil dilation is uncomfortable for the participants and requires ophthalmological expertise. Hence, we here investigated whether an individual's maximum PIPR can be validly obtained in a protocol that does not use mydriatics but rather increases the intensity of the light stimulus. In 18 participants (5 males, mean age ± SD: 34.6 ± 13.6 years) we evaluated the PIPR after exposure to intensified blue light (550 µW/cm²) provided to an undilated dynamic pupil. The test-retest reliability of the primary PIPR outcome parameter was very high, both between day-to-day assessments (Intraclass Correlation Coefficient (ICC) = 0.85), as well as between winter and summer assessments (ICC = 0.83). Compared to the PIPR obtained with the use of mydriatics and 160 µW/cm² blue light exposure, the method with intensified light without mydriatics showed almost zero bias according to Bland-Altman plots and had moderate to strong reliability (ICC = 0.67). In conclusion, for PIPR assessments, increasing the light intensity is a feasible and reliable alternative to pupil dilation to relieve the participant's burden and to allow for performance outside the ophthalmological clinic. PMID:27618116

  10. Highly efficient blue and warm white organic light-emitting diodes with a simplified structure

    NASA Astrophysics Data System (ADS)

    Li, Xiang-Long; Ouyang, Xinhua; Chen, Dongcheng; Cai, Xinyi; Liu, Ming; Ge, Ziyi; Cao, Yong; Su, Shi-Jian

    2016-03-01

    Two blue fluorescent emitters were utilized to construct simplified organic light-emitting diodes (OLEDs) and the remarkable difference in device performance was carefully illustrated. A maximum current efficiency of 4.84 cd A-1 (corresponding to a quantum efficiency of 4.29%) with a Commission Internationale de l’Eclairage (CIE) coordinate of (0.144, 0.127) was achieved by using N,N-diphenyl-4″-(1-phenyl-1H-benzo[d]imidazol-2-yl)-[1, 1‧:4‧, 1″-terphenyl]-4-amine (BBPI) as a non-doped emission layer of the simplified blue OLEDs without carrier-transport layers. In addition, simplified fluorescent/phosphorescent (F/P) hybrid warm white OLEDs without carrier-transport layers were fabricated by utilizing BBPI as (1) the blue emitter and (2) the host of a complementary yellow phosphorescent emitter (PO-01). A maximum current efficiency of 36.8 cd A-1 and a maximum power efficiency of 38.6 lm W-1 were achieved as a result of efficient energy transfer from the host to the guest and good triplet exciton confinement on the phosphorescent molecules. The blue and white OLEDs are among the most efficient simplified fluorescent blue and F/P hybrid white devices, and their performance is even comparable to that of most previously reported complicated multi-layer devices with carrier-transport layers.

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

    NASA Astrophysics Data System (ADS)

    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.

  12. Old chromophores, new photoactivation paradigms, trendy applications: flavins in blue light-sensing photoreceptors.

    PubMed

    Losi, Aba; Gärtner, Wolfgang

    2011-01-01

    The knowledge on the mechanisms by which blue light (BL) is sensed by diverse and numerous organisms, and of the physiological responses elicited by the BL photoreceptors, has grown remarkably during the last two decades. The basis for this "blue revival" was set by the identification and molecular characterization of long sought plant BL sensors, employing flavins as chromophores, chiefly cryptochromes and phototropins. The latter photosensors are the foundation members of the so-called light, oxygen, voltage (LOV)-protein family, largely spread among archaea, bacteria, fungi and plants. The accumulation of sequenced microbial genomes during the last years has added the BLUF (Blue Light sensing Using FAD) family to the BL photoreceptors and yielded the opportunity for intense "genome mining," which has presented to us the intriguing wealth of BL sensing in prokaryotes. In this contribution we provide an update of flavin-based BL sensors of the LOV and BLUF type, from prokaryotic microorganisms, with special emphasis to their light-activation pathways and molecular signal-transduction mechanisms. Rather than being a fully comprehensive review, this research collects the most recent discoveries and aims to unveil and compare signaling pathways and mechanisms of BL sensors. PMID:21352235

  13. Role of L-arginine in the biological effects of blue light

    NASA Astrophysics Data System (ADS)

    Makela, Anu M.

    2005-11-01

    Arginine, a semi-essential amino acid, and metabolites of arginine exert multiple biological effects. It has been known that arginine causes the release of various hormones such as insulin, glucagon, growth hormone, prolactin, and adrenal catecholamines. Arginine infusion also produces vasodilation, and in the kidney increased plasma flow accompanied by increases in glomerular filtration rate (GFR). Recent studies have showed that blue and red light irradiation in vitro and in vivo can increase production of nitric oxide (NO), superoxide anion, and related reactive oxygen species (ROS). These then can modulate the production and secretion of several cytokines and other mediators and play an important role as regulatory mediators in signaling processes which can then modulate the production, mobilization and homing of stem cells. It is proposed that some of the therapeutic effects of light can be considered to be due to the changes in the metabolism of L-arginine. The regulation of L-arginine turnover by the use of light at blue wavelengths between 400nm and 510nm can be the explanation for some of the observed effects of blue light: lowering of blood pressure, pain killing effect, regulating insulin production, anti-inflammatory action, and possible effects on the release and homing of stem cells.

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

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

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

  15. Almost-total absorption of light in thin, biperiodic, weakly-absorbing semiconductor gratings.

    PubMed

    Popov, Evgeny; Fehrembach, Anne-Laure; McPhedran, Ross C

    2016-07-25

    We consider the design of optical systems capable of providing near 100% absorption of visible light, consisting of a structured thin layer of a weakly absorbing semiconductor placed on top of a dielectric spacer layer and a metallic mirror layer. We generalise a system recently studied semi-analytically and experimentally by Stürmberg et al [Optica 3, 556 2016] which incorporated a grating layer of antimony sulphide and delivered high, narrow-band absorptance of normally-incident light for a single polarisation. We demonstrate that bi-periodic gratings can be optimised to deliver near-perfect absorptance of unpolarised light in the system, and comment on the wavelength and angular ranges over which the absorptance remains near 100%. We show that the properties of the systems studied depend on the interaction of multiple modes, and cannot be accurately modelled within the quasistatic approximation. PMID:27464093

  16. Synthesis and photophysics of a red-light absorbing supramolecular chromophore system.

    PubMed

    Rombouts, Jeroen A; Ravensbergen, Janneke; Frese, Raoul N; Kennis, John T M; Ehlers, Andreas W; Slootweg, J Chris; Ruijter, Eelco; Lammertsma, Koop; Orru, Romano V A

    2014-08-11

    In search of supramolecular antenna systems for light-harvesting applications, we report on a short and effective synthesis of a fused NDI-zinc-salphen-based chromophore (salphen = bis-salicylimide phenylene) and its photophysical properties. A supramolecular recognition motif is embedded into the chromophoric π-system of this compound. The fused π-chromophore behaves as one pigment, absorbs light between 600 and 750 nm and displays a modest Stokes shift. Upon binding pyridines, the compound (DATZnS) does not change its redox potentials, does not undergo any internal excited state quenching and does not appreciably alter its excited state lifetime. These notable properties define DATZnS as an alternative to porphyrin-based components used in supramolecular light-harvesting architectures. PMID:24965936

  17. Designing NHC-Copper(I) Dipyridylamine Complexes for Blue Light-Emitting Electrochemical Cells.

    PubMed

    Elie, Margaux; Sguerra, Fabien; Di Meo, Florent; Weber, Michael D; Marion, Ronan; Grimault, Adèle; Lohier, Jean-François; Stallivieri, Aurélie; Brosseau, Arnaud; Pansu, Robert B; Renaud, Jean-Luc; Linares, Mathieu; Hamel, Matthieu; Costa, Rubén D; Gaillard, Sylvain

    2016-06-15

    This study presents the influence of various substituents on the photophysical features of heteroleptic copper(I) complexes bearing both N-heterocyclic carbene (NHC) and dipyridylamine (dpa = dipyridylamine skeleton corresponding to ligand L1) ligands. The luminescent properties have been compared to our recently reported archetypal blue emitting [Cu(IPr)(dpa)][PF6] complex. The choice of the substituents on both ligands has been guided to explore the effect of the electron donor/acceptor and "push-pull" on the emission wavelengths and photoluminescence quantum yields. A selection of the best candidates in terms of their photophysical features were applied for developing the first blue light-emitting electrochemical cells (LECs) based on copper(I) complexes. The device analysis suggests that the main concern is the moderate redox stability of the complexes under high applied driving currents, leading to devices with moderate stabilities pointing to a proof-of-concept for further development. Nevertheless, under low applied driving currents the blue emission is stable, showing performance levels competitive to those reported for blue LECs based on iridium(III) complexes. Overall, this work provides valuable guidelines to tackle the design of enhanced NHC copper complexes for lighting applications in the near future. PMID:27224961

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

    PubMed Central

    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

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

    PubMed

    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

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

    NASA Astrophysics Data System (ADS)

    Wang, X.; Huang, J.

    2013-12-01

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

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

    PubMed Central

    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

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

    PubMed

    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. PMID:26891084

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

    PubMed

    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. PMID:27404623

  4. Controlling charge transport in blue organic light-emitting devices by chemical functionalization of host materials

    SciTech Connect

    Polikarpov, Evgueni; Koech, Phillip K.; Wang, Liang; Swensen, James S.; Cosimbescu, Lelia; Rainbolt, James E.; Von Ruden, Amber L.; Gaspar, Daniel J.; Padmaperuma, Asanga B.

    2011-01-18

    Generation of white light from OLEDs for general lighting applications requires a highly efficient blue component. However, a stable and power efficient blue OLED component with simple device architecture remains a significant challenge partly due to lack of appropriate host materials. Here we report the photophysical and device properties of ambipolar host phosphine oxide based materials. In this work, we studied the effect of the structural modification made to phosphine oxide-based hosts on the charge balance. We observed significant changes in charge transport within the host occurred upon small modifications to their chemical structure. As a result, an alteration of the chemical design of these materials allows for the control of charge balance of the OLED.

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

    NASA Technical Reports Server (NTRS)

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

    1994-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

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

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

    PubMed

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

    2013-01-01

    Antioxidant compounds protect plants against oxidative stress caused by environmental conditions. Different light qualities, such as UV-A radiation and blue light, have shown positive effects on the production of phenols in plants. Kalanchoe pinnata (Lamarck) Persoon (Crassulaceae) is used for treating wounds and inflammations. Some of these beneficial effects are attributed to the antioxidant activity of plant components. We investigated the effects of blue light and UV-A radiation supplementation on the total phenol content, antioxidant activity and chromatographic profile of aqueous extracts from leaves of K. pinnata. Monoclonal plants were grown under white light, white plus blue light and white plus UV-A radiation. Supplemental blue light improved the antioxidant activity and changed the phenolic profile of the extracts. Analysis by HPLC of supplemental blue-light plant extracts revealed a higher proportion of the major flavonoid quercetin 3-O-α-L-arabinopyranosyl (1→2) α-L-rhamnopyranoside, as well as the presence of a wide variety of other phenolic substances. These findings may explain the higher antioxidant activity observed for this extract. Blue light is proposed as a supplemental light source in the cultivation of K. pinnata, to improve its antioxidant activity. PMID:23057576

  8. Gap state related blue light emitting boron-carbon core shell structures

    NASA Astrophysics Data System (ADS)

    Singh, Paviter; Kaur, Manpreet; Singh, Bikramjeet; Kaur, Gurpreet; Singh, Kulwinder; Kumar, Manjeet; Bala, Rajni; Thakur, Anup; Kumar, Akshay

    2016-05-01

    Boron- carbon core shell structures have been synthesized by solvo-thermal synthesis route. The synthesized material is highly pure. X-ray diffraction analysis confirms the reduction of reactants in to boron and carbon. Scanning Electron Microscopy (SEM) analysis showed that the shell is uniform with average thickness of 340 nm. Photo luminescence studies showed that the material is blue light emitting with CIE color coordinates: x=0.16085, y=0.07554.

  9. Light Perception in Two Strictly Subterranean Rodents: Life in the Dark or Blue?

    PubMed Central

    Kott, Ondřej; Šumbera, Radim; Němec, Pavel

    2010-01-01

    Background The African mole-rats (Bathyergidae, Rodentia) are strictly subterranean, congenitally microphthalmic rodents that are hardly ever exposed to environmental light. Because of the lack of an overt behavioural reaction to light, they have long been considered to be blind. However, recent anatomical studies have suggested retention of basic visual capabilities. In this study, we employed behavioural tests to find out if two mole-rat species are able to discriminate between light and dark, if they are able to discriminate colours and, finally, if the presence of light in burrows provokes plugging behaviour, which is assumed to have a primarily anti-predatory function. Methodology/Principal Finding We used a binary choice test to show that the silvery mole-rat Heliophobius argenteocinereus and the giant mole-rat Fukomys mechowii exhibit a clear photoavoidance response to full-spectrum (“white”), blue and green-yellow light, but no significant reaction to ultraviolet or red light during nest building. The mole-rats thus retain dark/light discrimination capabilities and a capacity to perceive short to medium-wavelength light in the photopic range of intensities. These findings further suggest that the mole-rat S opsin has its absorption maximum in the violet/blue part of the spectrum. The assay did not yield conclusive evidence regarding colour discrimination. To test the putative role of vision in bathyergid anti-predatory behaviour, we examined the reaction of mole-rats to the incidence of light in an artificial burrow system. The presence of light in the burrow effectively induced plugging of the illuminated tunnel. Conclusion/Significance Our findings suggest that the photopic vision is conserved and that low acuity residual vision plays an important role in predator avoidance and tunnel maintenance in the African mole-rats. PMID:20676369

  10. Dissimilarity of yellow-blue surfaces under neutral light sources differing in intensity: separate contributions of light intensity and chroma.

    PubMed

    Tokunaga, Rumi; Logvinenko, Alexander D; Maloney, Laurence T

    2008-01-01

    Observers viewed two side-by-side arrays each of which contained three yellow Munsell papers, three blue, and one neutral Munsell. Each array was illuminated uniformly and independently of the other. The neutral light source intensities were 1380, 125, or 20 lux. All six possible combinations of light intensities were set as illumination conditions. On each trial, observers were asked to rate the dissimilarity between each chip in one array and each chip in the other by using a 30-point scale. Each pair of surfaces in each illumination condition was judged five times. We analyzed this data using non-metric multi-dimensional scaling to determine how light intensity and surface chroma contributed to dissimilarity and how they interacted. Dissimilarities were captured by a three-dimensional configuration in which one dimension corresponded to differences in light intensity. PMID:18598408

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

    PubMed

    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. PMID:27261063

  12. Cool and warm hybrid white organic light-emitting diode with blue delayed fluorescent emitter both as blue emitter and triplet host

    PubMed Central

    Cho, Yong Joo; Yook, Kyoung Soo; Lee, Jun Yeob

    2015-01-01

    A hybrid white organic light-emitting diode (WOLED) with an external quantum efficiency above 20% was developed using a new blue thermally activated delayed fluorescent material, 4,6-di(9H-carbazol-9-yl)isophthalonitrile (DCzIPN), both as a blue emitter and a host for a yellow phosphorescent emitter. DCzIPN showed high quantum efficiency of 16.4% as a blue emitter and 24.9% as a host for a yellow phosphorescent emitter. The hybrid WOLEDs with the DCzIPN host based yellow emitting layer sandwiched between DCzIPN emitter based blue emitting layers exhibited high external quantum efficiency of 22.9% with a warm white color coordinate of (0.39, 0.43) and quantum efficiency of 21.0% with a cool white color coordinate of (0.31, 0.33) by managing the thickness of the yellow emitting layer. PMID:25598436

  13. Cool and warm hybrid white organic light-emitting diode with blue delayed fluorescent emitter both as blue emitter and triplet host

    NASA Astrophysics Data System (ADS)

    Cho, Yong Joo; Yook, Kyoung Soo; Lee, Jun Yeob

    2015-01-01

    A hybrid white organic light-emitting diode (WOLED) with an external quantum efficiency above 20% was developed using a new blue thermally activated delayed fluorescent material, 4,6-di(9H-carbazol-9-yl)isophthalonitrile (DCzIPN), both as a blue emitter and a host for a yellow phosphorescent emitter. DCzIPN showed high quantum efficiency of 16.4% as a blue emitter and 24.9% as a host for a yellow phosphorescent emitter. The hybrid WOLEDs with the DCzIPN host based yellow emitting layer sandwiched between DCzIPN emitter based blue emitting layers exhibited high external quantum efficiency of 22.9% with a warm white color coordinate of (0.39, 0.43) and quantum efficiency of 21.0% with a cool white color coordinate of (0.31, 0.33) by managing the thickness of the yellow emitting layer.

  14. High-Efficiency Blue Organic Light-Emitting Diodes Based on Thermally Activated Delayed Fluorescence from Phenoxaphosphine and Phenoxathiin Derivatives.

    PubMed

    Lee, Sae Youn; Adachi, Chihaya; Yasuda, Takuma

    2016-06-01

    High-efficiency blue thermally activated delayed fluorescence (TADF) molecules, consisting of phenoxaphosphine oxide and phenoxathiin dioxide as acceptor units and 9,9-dimethylacridan as a donor unit, are reported. Maximum external electroluminescence quantum efficiencies of up to 20.5% are achieved in blue organic light-emitting diodes (OLEDs) by employing these materials as TADF emitters. PMID:27059783

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

    PubMed

    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 < 0.05). HPLC demonstrated various porphyrin patterns and amounts of porphyrins in bacteria. Following phototherapy, the mean survival fractions were reduced by 28.5 and 48.2% in plaque suspensions and biofilms, respectively, (p < 0.05). DNA probe analysis showed significant

  16. Laser Writing Block Copolymer Self-Assembly on Graphene Light-Absorbing Layer.

    PubMed

    Jin, Hyeong Min; Lee, Seung Hyun; Kim, Ju Young; Son, Seung-Woo; Kim, Bong Hoon; Lee, Hwan Keon; Mun, Jeong Ho; Cha, Seung Keun; Kim, Jun Soo; Nealey, Paul F; Lee, Keon Jae; Kim, Sang Ouk

    2016-03-22

    Recent advance of high-power laser processing allows for rapid, continuous, area-selective material fabrication, typically represented by laser crystallization of silicon or oxides for display applications. Two-dimensional materials such as graphene exhibit remarkable physical properties and are under intensive development for the manufacture of flexible devices. Here we demonstrate an area-selective ultrafast nanofabrication method using low intensity infrared or visible laser irradiation to direct the self-assembly of block copolymer films into highly ordered manufacturing-relevant architectures at the scale below 12 nm. The fundamental principles underlying this light-induced nanofabrication mechanism include the self-assembly of block copolymers to proceed across the disorder-order transition under large thermal gradients, and the use of chemically modified graphene films as a flexible and conformal light-absorbing layers for transparent, nonplanar, and mechanically flexible surfaces. PMID:26871736

  17. 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.

    PubMed

    Retamal, José Ramón Durán; Oubei, Hassan Makine; Janjua, Bilal; Chi, Yu-Chieh; Wang, Huai-Yung; Tsai, Cheng-Ting; Ng, Tien Khee; Hsieh, Dan-Hua; Kuo, Hao-Chung; Alouini, Mohamed-Slim; He, Jr-Hau; Lin, Gong-Ru; Ooi, Boon S

    2015-12-28

    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. PMID:26832029

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

    NASA Astrophysics Data System (ADS)

    Shapiro, E. L.; Szprengiel, J.; Sareen, N.; Jen, C. N.; Giordano, M. R.; McNeill, V. F.

    2009-01-01

    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 ((NH4)2SO4) or sodium chloride (NaCl) was present in the aqueous phase. The products formed in the (NH4)2SO4 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 that an aldol condensation mechanism is active in the glyoxal-(NH4)2SO4system, resulting in the formation of pi-conjugated products. If similar products are formed in atmospheric aerosol particles, they could change the optical properties of the seed aerosol over its lifetime.

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

    NASA Astrophysics Data System (ADS)

    Hegg, Dean A.; Warren, Stephen G.; Grenfell, Thomas C.; Doherty, Sarah J.; Clarke, Antony D.

    2010-11-01

    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.

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

    NASA Technical Reports Server (NTRS)

    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.

  1. Influence of green, red and blue light emitting diodes on multiprotein complex proteins and photosynthetic activity under different light intensities in lettuce leaves (Lactuca sativa L.).

    PubMed

    Muneer, Sowbiya; Kim, Eun Jeong; Park, Jeong Suk; Lee, Jeong Hyun

    2014-01-01

    The objective of this study was to investigate the response of light emitting diodes (LEDs) at different light intensities (70 and 80 for green LEDs, 88 and 238 for red LEDs and 80 and 238 μmol m-2 s-1 for blue LEDs) at three wavelengths in lettuce leaves. Lettuce leaves were exposed to (522 nm), red (639 nm) and blue (470 nm) LEDs of different light intensities. Thylakoid multiprotein complex proteins and photosynthetic metabolism were then investigated. Biomass and photosynthetic parameters increased with an increasing light intensity under blue LED illumination and decreased when illuminated with red and green LEDs with decreased light intensity. The expression of multiprotein complex proteins including PSII-core dimer and PSII-core monomer using blue LEDs illumination was higher at higher light intensity (238 μmol m-2 s-1) and was lowered with decreased light intensity (70-80 μmol m-2 s-1). The responses of chloroplast sub-compartment proteins, including those active in stomatal opening and closing, and leaf physiological responses at different light intensities, indicated induced growth enhancement upon illumination with blue LEDs. High intensity blue LEDs promote plant growth by controlling the integrity of chloroplast proteins that optimize photosynthetic performance in the natural environment. PMID:24642884

  2. Inhibition of germination of dormant barley (Hordeum vulgare L.) grains by blue light as related to oxygen and hormonal regulation.

    PubMed

    Hoang, Hai Ha; Sechet, Julien; Bailly, Christophe; Leymarie, Juliette; Corbineau, Françoise

    2014-06-01

    Germination of primary dormant barley grains is promoted by darkness and temperatures below 20 °C, but is strongly inhibited by blue light. Exposure under blue light at 10 °C for periods longer than five days, results in a progressive inability to germinate in the dark, considered as secondary dormancy. We demonstrate that the inhibitory effect of blue light is reinforced in hypoxia. The inhibitory effect of blue light is associated with an increase in embryo abscisic acid (ABA) content (by 3.5- to 3.8-fold) and embryo sensitivity to both ABA and hypoxia. Analysis of expression of ABA metabolism genes shows that increase in ABA mainly results in a strong increase in HvNCED1 and HvNCED2 expression, and a slight decrease in HvABA8'OH-1. Among the gibberellins (GA) metabolism genes examined, blue light decreases the expression of HvGA3ox2, involved in GA synthesis, increases that of GA2ox3 and GA2ox5, involved in GA catabolism, and reduces the GA signalling evaluated by the HvExpA11 expression. Expression of secondary dormancy is associated with maintenance of high embryo ABA content and a low HvExpA11 expression. The partial reversion of the inhibitory effect of blue light by green light also suggests that cryptochrome might be involved in this hormonal regulation. PMID:24256416

  3. Highly efficient white organic light-emitting diodes based on fluorescent blue emitters

    NASA Astrophysics Data System (ADS)

    Rosenow, Thomas C.; Furno, Mauro; Reineke, Sebastian; Olthof, Selina; Lüssem, Björn; Leo, Karl

    2010-12-01

    Beside inorganic LEDs and fluorescent lamps, organic light-emitting diodes (OLEDs) are evolving into a serious alternative to incandescent lamps. Up to now, it was assumed that all-phosphorescent OLEDs are required for reaching sufficiently high efficiencies. However, the stability of phosphorescent blue emitters is a major challenge. We present a novel approach to achieve highly efficient (up to 90 lm/W at 1000 cd/m2 using a macroextractor) white light emission from OLEDs. The here presented combination of a fluorescent blue and a phosphorescent red emitter simultaneously allows for a strong blue emission and efficient triplet transfer to the phosphor. The spectrum is extended in the green and yellow region by a full phosphorescent unit stacked on top of the triplet harvesting device. This superposition of four different emitters results in color coordinates close to illuminant A and a color rendering index of 80. Furthermore, color stability is given with respect to varying driving conditions and estimations of the electrical and optical efficiencies are provided.

  4. Post-illumination pupil response after blue light: Reliability of optimized melanopsin-based phototransduction assessment.

    PubMed

    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

  5. Measuring the 3D shape of high temperature objects using blue sinusoidal structured light

    NASA Astrophysics Data System (ADS)

    Zhao, Xianling; Liu, Jiansheng; Zhang, Huayu; Wu, Yingchun

    2015-12-01

    The visible light radiated by some high temperature objects (less than 1200 °C) almost lies in the red and infrared waves. It will interfere with structured light projected on a forging surface if phase measurement profilometry (PMP) is used to measure the shapes of objects. In order to obtain a clear deformed pattern image, a 3D measurement method based on blue sinusoidal structured light is proposed in this present work. Moreover, a method for filtering deformed pattern images is presented for correction of the unwrapping phase. Blue sinusoidal phase-shifting fringe pattern images are projected on the surface by a digital light processing (DLP) projector, and then the deformed patterns are captured by a 3-CCD camera. The deformed pattern images are separated into R, G and B color components by the software. The B color images filtered by a low-pass filter are used to calculate the fringe order. Consequently, the 3D shape of a high temperature object is obtained by the unwrapping phase and the calibration parameter matrixes of the DLP projector and 3-CCD camera. The experimental results show that the unwrapping phase is completely corrected with the filtering method by removing the high frequency noise from the first harmonic of the B color images. The measurement system can complete the measurement in a few seconds with a relative error of less than 1 : 1000.

  6. Macroscopic effect of blue light cure on wound healing in NMRI mice NMRI

    PubMed Central

    Jaffary, Fariba; Changizi, Vahid; Mardani, Homeira; Kakanezhadian, Parisa; Javadi, Faezeh Moshref; Nilforoushzadeh, Mohammad Ali; Haftbaradaran, Elaheh

    2014-01-01

    Background: Wound healing is a complex process and has been an ongoing challenge all over the world. Some studies have suggested light cure as a modality to accelerate wound repair. It can induce fibroblast proliferation, increase collagen synthesis and activate cellular processes involved in expression of procollagen type I and III mRNA. This study was designed to assess the macroscopic effect of halogen dental curing blue light on full-thickness open wound healing in NMRI mice. Materials and Methods: Forty male NMRI mice were divided into control and treatment groups. A full-thickness wound of 6 mm in diameter was induced on the lower back of all mice under general anesthesia and sterile conditions. The mice of the treatment group received a 5-min exposure of halogen light Coltolux II (QHL), 420-500 nm, daily for 7 days. The diameter of the wound was measured in both the treatment and the control groups every second day up to Day 14. Data were analyzed by SPSS version 12 software using Student's t-test. A significance level of P ≤ 0.05 was considered for each comparison. Results: There was a significant difference in wound diameter between the control and the treatment groups at all measurements after Day 3 (P ≤ 0/05). Conclusion: The results of this study suggest improvement of full-thickness wound healing by daily irradiation of halogen dental curing blue light of 420-500 nm for 7 days. PMID:24804180

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

    PubMed

    Hlavinka, Jan; Nauš, Jan; Fellner, Martin

    2013-08-01

    It was reported earlier that 7B-1 mutant in tomato (Solanum lycopersicum L.), an ABA overproducer, is defective in blue light (BL) signaling leading to BL-specific resistance to abiotic and biotic stresses. In this work, we examine responses of stomata to blue, red and white lights, fusicoccin, anion channel blockers (anthracene-9-carboxylic acid; 9-AC and niflumic acid; NIF) and ABA. Our results showed that the aperture of 7B-1 stomata does not increase in BL, suggesting that 7B-1 mutation impairs an element of BL signaling pathway involved in stomatal opening. Similar stomatal responses of 7B-1 and wild type (WT) to fusicoccin or 9-AC points out that activity of H(+)-ATPase and 9-AC-sensitive anion channels per se is not likely affected by the mutation. Since 9-AC restored stomatal opening of 7B-1 in BL, it seems that 9-AC and BL could block similar type of anion channels. The stomata of both genotypes did not respond to NIF neither in darkness nor in any light conditions tested. In light, 9-AC but not NIF restored stomatal opening inhibited by ABA in WT and 7B-1. We suggest that in comparison to WT, the activity of S-type anion channels in 7B-1 is more promoted by increased ABA content, and less reduced by BL, because of the mutant resistance to BL. PMID:23759105

  8. Red-blue-green solid state light sources using a narrow line-width green phosphor.

    PubMed

    Liu, A; Khanna, A; Dutta, P S; Shur, M

    2015-04-01

    We demonstrate that using a narrow line-width green phosphor with the peak wavelength closely aligned with the peak in the human eye sensitivity significantly improves the Luminous Efficacy of Radiation (LER) for Red-Green-Blue (RGB) emitters. Compared to the traditional RGB sources, the improvement in LER of 20 lm/W can be achieved. Combining the narrow band green phosphor with conventional wide band red and blue phosphors allows for trading off these improvements against the deviation from the Planckian locus for even higher LER. The light sources with the narrow line green phosphor are particularly promising for high energy efficiency and high intensity illumination, where somewhat compromises can be made in the color quality such as in automotive, outdoor spaces, industrial ware-houses, public places (train stations, airports) etc.. PMID:25968796

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

    NASA Astrophysics Data System (ADS)

    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

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

    PubMed

    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 < 0.05) than with the control eyewear. Sleep efficacy and sleep latency were significantly superior for wearers of the blue-light shield (P < 0.05 for both), and this group reported greater sleepiness during portable device use compared to those using the control eyewear. Participants rated the blue-light shield as providing acceptable visual quality. PMID:26730983

  11. Stable blue thermally activated delayed fluorescent organic light-emitting diodes with three times longer lifetime than phosphorescent organic light-emitting diodes.

    PubMed

    Kim, Mounggon; Jeon, Sang Kyu; Hwang, Seok-Ho; Lee, Jun Yeob

    2015-04-17

    High quantum efficiency above 18% and extended lifetime three times longer than that of phosphorescent organic light-emitting diodes (OLEDs) are demonstrated in blue thermally activated delayed fluorescent OLEDs. PMID:25757226

  12. Highly efficient greenish-blue platinum-based phosphorescent organic light-emitting diodes on a high triplet energy platform

    SciTech Connect

    Chang, Y. L. Gong, S. White, R.; Lu, Z. H.; Wang, X.; Wang, S.; Yang, C.

    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.

  13. Light Emitting Diode-Generated Blue Light Modulates Fibrosis Characteristics: Fibroblast Proliferation, Migration Speed, and Reactive Oxygen Species Generation

    PubMed Central

    Mamalis, Andrew; Garcha, Manveer; Jagdeo, Jared

    2016-01-01

    Background and Objective Blue light is part of the visible light spectrum that does not generate harmful DNA adducts associated with skin cancer and photoaging, and may represent a safer therapeutic modality for treatment of keloid scars and other fibrotic skin diseases. Our laboratory previously demonstrated that light-emitting diode (LED) red and infrared light inhibits proliferation of skin fibroblasts. Moreover, different wavelengths of light can produce different biological effects. Furthermore, the effects of LED blue light (LED-BL) on human skin fibroblasts are not well characterized. This study investigated the effects of LED-BL on human skin fibroblast proliferation, viability, migration speed, and reactive oxygen-species (ROS) generation. Methods and Materials Irradiation of adult human skin fibroblasts using commercially-available LED-BL panels was performed in vitro, and modulation of proliferation and viability was quantified using the trypan blue dye exclusion assay, migratory speed was assessed using time-lapse video microscopy, and intracellular ROS generation was measured using the dihydrorhodamine flow cytometry assay. Statistical differences between groups were determined by ANOVA and Student s t-test. Results Human skin fibroblasts treated with LED-BL fluences of 5, 30, 45, and 80 J/cm2 demonstrated statistically significant dose-dependent decreases in relative proliferation of 8.4%, 29.1%, 33.8%, 51.7%, and 55.1%, respectively, compared to temperature and environment matched bench control plates, respectively. LED-BL fluences of 5, 30, 45 and 80 J/cm2 decreased fibroblast migration speed to 95 ± 7.0% (p = 0.64), 81.3 ± 5.5% (p = 0.021), 48.5 ± 2.7% (p < 0.0001), and 32.3 ± 1.9% (p < 0.0001), respectively, relative to matched controls. LED fluences of 5, 10, 30, and 80 J/cm2 resulted in statistically significant increases in reactive oxygen species of 110.4%, 116.6%, 127.5%, and 130%, respectively, relative to bench controls. Conclusion At

  14. Red-green-blue light sensitivity of oxide nanowire transistors for transparent display applications

    NASA Astrophysics Data System (ADS)

    Lee, Sumi; Kim, Seongmin; Janes, David B.; Meyyappan, M.; Ju, Sanghyun

    2013-01-01

    In this study, the sensitivity of oxide nanowire transistors under red (R, 470 nm), green (G, 530 nm), and blue (B, 625 nm) light illumination was investigated. As the wavelength of light illuminating the nanowire channel region became shorter, a negative shift of threshold voltage, degradation of subthreshold slope, and increase of on-current were observed. This phenomenon can be explained in terms of photo-induced holes, creating interfacial traps between the gate dielectric and nanowire channel or reacting with oxygen ions on the surface of the nanowires. Thus, the attempt to minimize characteristic changes due to all RGB light sources was performed by employing ultraviolet-ozone treatment and passivation process. As a result, we could successfully fabricate oxide nanowire transistors providing high optical reliability which has broadened the possibilities for applying it to transparent and/or flexible pixel operation circuitry for displays with high optical reliability.

  15. Phototropins do not alter accumulation of evening-phased circadian transcripts under blue light

    PubMed Central

    Litthauer, Suzanne; Battle, Martin W.; Jones, Matthew A.

    2016-01-01

    ABSTRACT The circadian system induces rhythmic variation in a suite of biochemical and physiological processes that serve to optimise plant growth in diel cycles. To be of greatest utility, these rhythmic behaviors are coordinated with regular environmental changes such as the rising and setting of the sun. Photoreceptors, along with metabolites produced during photosynthesis, act to synchronise the internal timing mechanism with lighting cues. We have recently shown that phototropins help maintain robust rhythms of photosynthetic operating efficiency (φPSII or Fq′/Fm′) under blue light, although rhythmic accumulation of morning-phased circadian transcripts in the nucleus was unaffected. Here we report that evening-phased nuclear clock transcripts were also unaffected. We also observe that rhythms of nuclear clock transcript accumulation are maintained in phototropin mutant plants under a fluctuating lighting regime that induced a loss of Fq′/Fm′ rhythms. PMID:26653107

  16. Efficiency and Color Coordinate Improvement Using Codopants in Blue Organic Light-Emitting Diode

    NASA Astrophysics Data System (ADS)

    Wang, Xiu Ru; Chen, Jiang Shan; You, Han; Ma, Dong Ge; Sun, Run Guang

    2005-12-01

    The codoping method is applied to fabricate efficient blue organic light-emitting diodes (OLEDs). With the same structure of indium-tin oxide (ITO)/N,N'-bis(1-naphthyl)-N,N'-diphenyl-1,1'-biphenyl-4,4'diamine (NPB)(80 nm)/light-emitting layer (30 nm)/tris-(8-hydroxy-quinoline)aluminum (Alq3) (20 nm)/LiF (1 nm)/Al (120 nm), a set of three devices was manufactured for comparison. For Devices 1, 2, and 3, the light-emitting layers are 9,10-di(2-naphthyl)anthracene (ADN):4,4'-(1,4-phenylenedi-2,1-ethene diyl)bis[N,N-bis(4-methylphenyl)-benzenamine] (DPAVB) (1 wt %), ADN:2,5,8,11-tetra-(t-butyl)-perylene (TBPE) (1 wt %), and ADN:DPAVB (0.3 wt %):TBPE (0.7 wt %), respectively. It is found that the codoped Device 3 has the highest maximum luminance, Electroluminescence (EL) quantum efficiency and color saturation. Further study on the effect of the codopants was through a relative photoluminescence (PL) quantum efficiency measurement. The result shows that the relative PL efficiencies of Devices 1, 2, and 3 are 15.6, 19.3, and 24%, respectively, as determined using an integrating sphere system excited at 375 nm. The codoping method improves the EL efficiency intrinsically. Codopants of the heterogeneous light-emitting molecules may decrease the possibility of self-quenching from the interaction of the homogenous molecules at the same total doping concentration. Furthermore, the decrease in the interaction of homogenous molecules suppresses the light emission from the aggregations thus narrowing the emission spectrum, and results in saturated blue light emission.

  17. A qualitative study of the perceived effects of blue lights in washrooms on people who use injection drugs

    PubMed Central

    2013-01-01

    Background Blue lights are sometimes placed in public washrooms to discourage injection drug use. Their effectiveness has been questioned and concerns raised that they are harmful but formal research on the issue is limited to a single study. We gathered perceptions of people who use injection drugs on the effects of blue lights with the aim of informing harm reduction practice. Methods We interviewed 18 people in two Canadian cities who currently or previously used injection drugs to better understand their perceptions of the rationale for and consequences of blue lights in public washrooms. Results Participants described a preference for private places to use injection drugs, but explained that the need for an immediate solution would often override other considerations. While public washrooms were in many cases not preferred, their accessibility and relative privacy appear to make them reasonable compromises in situations involving urgent injecting. Participants understood the aim of blue lights to be to deter drug use. The majority had attempted to inject in a blue-lit washroom. While there was general agreement that blue lights do make injecting more difficult, a small number of participants were entirely undeterred by them, and half would use a blue-lit washroom if they needed somewhere to inject urgently. Participants perceived that, by making veins less visible, blue lights make injecting more dangerous. By dispersing public injection drug use to places where it is more visible, they also make it more stigmatizing. Despite recognizing these harms, more than half of the participants were not opposed to the continued use of blue lights. Conclusions Blue lights are unlikely to deter injection drugs use in public washrooms, and may increase drug use-related harms. Despite recognizing these negative effects, people who use injection drugs may be reluctant to advocate against their use. We attempt to reconcile this apparent contradiction by interpreting blue

  18. Potential climatic effects of light absorbing particles over the Third Pole regions

    NASA Astrophysics Data System (ADS)

    Ji, Zhenming; Kang, Shichang

    2016-04-01

    Light absorbing particles (LAPs) have important impact on regional climate over the Third Pole regions. Carbonaceous and mineral aerosols, which are considered as the anthropogenic and natural sources respectively, can absorb and scatter incident solar radiation in the atmosphere. Meanwhile, LAPs deposition in snow/ice can also change the surface albedo, resulting in perturbations in the surface radiation balance. However, most studies that have made quantitative assessments of the climatic effect of LAPs over the Third Pole regions did not consider the impact of dust on snow/ice at the surface. In this study, a regional climate model RegCM4.3.4 (Regional Climate Model version 4.3.4) coupled with an aerosol-snow/ice feedback module was used to investigate the emission, distribution, and deposition of carbonaceous and dust aerosols. The study was focused on the two issues: 1) the evaluation of model performance; 2) the assessment of climatic effects induced by carbonaceous and mineral dust aerosols, respectively.

  19. Interannual variations of light-absorbing particles in snow on Arctic sea ice

    NASA Astrophysics Data System (ADS)

    Doherty, Sarah J.; Steele, Michael; Rigor, Ignatius; Warren, Stephen G.

    2015-11-01

    Samples of snow on sea ice were collected in springtime of the 6 years 2008-2013 in the region between Greenland, Ellesmere Island, and the North Pole (82°N -89°N, 0°W-100°W). The meltwater was passed through filters, whose spectral absorption was then measured to determine the separate contributions by black carbon (BC) and other light-absorbing impurities. The median mixing ratio of BC across all years' samples was 4 ± 3 ng g-1, and the median fraction of absorption due to non-BC absorbers was 36 ± 11%. Variances represent both spatial and interannual variability; there was no interannual trend in either variable. The absorption Ångström exponent, however, decreased with latitude, suggesting a transition from dominance by biomass-burning sources in the south to an increased influence by fossil-fuel-burning sources in the north, consistent with earlier measurements of snow in Svalbard and at the North Pole.

  20. One-Dimensional Al4O4C Ceramics: A New Type of Blue Light Emitter

    PubMed Central

    Sun, Yong; Chen, Yuanzheng; Ding, Cairong; Yang, Guowei; Ma, Yanming; Wang, Chengxin

    2013-01-01

    Ceramic Al4O4C, which has few active functions, has been used as an additive in carbon-containing refractory materials to improve their oxidation resistance and thermal properties. Herein, the crystal and electronic structures of this novel material were systematically investigated for opto-electrical applications, which revealed interesting fluorescence features via photoluminescence (PL) and cathode luminescence (CL). When a 325 nm laser was focused on one end of a single Al4O4C needle, the entire needle was illuminated by the blue emission, which implies that this material exhibits excellent waveguide properties. Interestingly, the thin end exhibited the highest light intensity even though the excited region was located at the thick end. We believe the reason for this observed behaviour is related to the excellent waveguide behaviour as well as to the needle shape, which induces this intriguing blue-light convergence effect. Ab initio calculations demonstrated that the emission light emanates from the interband transition.

  1. Proton transfer to flavin stabilizes the signaling state of the blue light receptor plant cryptochrome.

    PubMed

    Hense, Anika; Herman, Elena; Oldemeyer, Sabine; Kottke, Tilman

    2015-01-16

    Plant cryptochromes regulate the circadian rhythm, flowering time, and photomorphogenesis in higher plants as responses to blue light. In the dark, these photoreceptors bind oxidized FAD in the photolyase homology region (PHR). Upon blue light absorption, FAD is converted to the neutral radical state, the likely signaling state, by electron transfer via a conserved tryptophan triad and proton transfer from a nearby aspartic acid. Here we demonstrate, by infrared and time-resolved UV-visible spectroscopy on the PHR domain, that replacement of the aspartic acid Asp-396 with cysteine prevents proton transfer. The lifetime of the radical is decreased by 6 orders of magnitude. This short lifetime does not permit to drive conformational changes in the C-terminal extension that have been associated with signal transduction. Only in the presence of ATP do both the wild type and mutant form a long-lived radical state. However, in the mutant, an anion radical is formed instead of the neutral radical, as found previously in animal type I cryptochromes. Infrared spectroscopic experiments demonstrate that the light-induced conformational changes of the PHR domain are conserved in the mutant despite the lack of proton transfer. These changes are not detected in the photoreduction of the non-photosensory d-amino acid oxidase to the anion radical. In conclusion, formation of the anion radical is sufficient to generate a protein response in plant cryptochromes. Moreover, the intrinsic proton transfer is required for stabilization of the signaling state in the absence of ATP. PMID:25471375

  2. Proton Transfer to Flavin Stabilizes the Signaling State of the Blue Light Receptor Plant Cryptochrome*

    PubMed Central

    Hense, Anika; Herman, Elena; Oldemeyer, Sabine; Kottke, Tilman

    2015-01-01

    Plant cryptochromes regulate the circadian rhythm, flowering time, and photomorphogenesis in higher plants as responses to blue light. In the dark, these photoreceptors bind oxidized FAD in the photolyase homology region (PHR). Upon blue light absorption, FAD is converted to the neutral radical state, the likely signaling state, by electron transfer via a conserved tryptophan triad and proton transfer from a nearby aspartic acid. Here we demonstrate, by infrared and time-resolved UV-visible spectroscopy on the PHR domain, that replacement of the aspartic acid Asp-396 with cysteine prevents proton transfer. The lifetime of the radical is decreased by 6 orders of magnitude. This short lifetime does not permit to drive conformational changes in the C-terminal extension that have been associated with signal transduction. Only in the presence of ATP do both the wild type and mutant form a long-lived radical state. However, in the mutant, an anion radical is formed instead of the neutral radical, as found previously in animal type I cryptochromes. Infrared spectroscopic experiments demonstrate that the light-induced conformational changes of the PHR domain are conserved in the mutant despite the lack of proton transfer. These changes are not detected in the photoreduction of the non-photosensory d-amino acid oxidase to the anion radical. In conclusion, formation of the anion radical is sufficient to generate a protein response in plant cryptochromes. Moreover, the intrinsic proton transfer is required for stabilization of the signaling state in the absence of ATP. PMID:25471375

  3. Improvement of operation voltage and efficiency in inverted blue phosphorescent organic light-emitting devices

    NASA Astrophysics Data System (ADS)

    Chang, Chih-Hao; Huang, Hao Siang; Su, Yu-De; Liang, Yi-Hu; Chang, Yu-Shuo; Chiu, Chuan-Hao; Chang, Hsin-Hua

    2013-09-01

    Inverted organic light-emitting diodes (IOLEDs) have drawn considerable attention for use in active-matrix OLED (AMOLED) displays because of their easy integration with n-channel metal-oxide-based thin film transistors (TFTs). The most crucial issue for IOLEDs is the poor electron injection caused by the bottom cathode. According to previous reports, the turn-on voltages of FIrpic-based IOLEDs are within a range from 4 to 8 V. In this study, we focus on developing bottom-emission IOLEDs with low operating voltages through the use of adequate-charge injection materials. We successfully demonstrate a turn-on voltage as low as 3.7 V for blue phosphorescent IOLEDs. The effective electron injection layers (EIL) were constructed by combining an ultrathin aluminum layer, an alkali metal oxide layer and an organic layer doped with alkali metal oxide, allowing for the effective adjustment of the carrier balance in IOLEDs. The peak efficiencies of the IOLEDs reached 15.6%, 31.8 cd/A and 23.4 lm/W. An external nanocomposite scattering layer was used to further improve light extraction efficiency. The IOLEDs equipped with the SiO2 nanocomposite scattering layer respectively provided performance improvements of 1.3 and 1.5 times that of pristine blue phosphorescent IOLEDs at practical luminance levels of 100 cd/m2 and 1000 cd/m2. Through sophisticated EIL and external light-extraction structures, we obtained blue phosphorescent IOLEDs with satisfactory efficiency and low operation voltages, thereby demonstrating the great potential of nanocomposite film for application in IOLEDs.

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

    DOEpatents

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

    2000-01-01

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

  5. Hydrogel-Coated Near Infrared Absorbing Nanoshells as Light-Responsive Drug Delivery Vehicles

    PubMed Central

    2015-01-01

    Nanoparticle drug delivery carriers that can modulate drug release based on an exogenous signal, such as light, are of great interest, especially for improving cancer therapy. A light-activated delivery vehicle was fabricated by synthesizing a thin, thermally responsive poly(N-isopropylacrylamide-co-acrylamide) hydrogel coating directly onto the surfaces of individual near-infrared (NIR) absorbing gold-silica nanoshells. This hydrogel was designed to be in a swollen state under physiological conditions and expel large amounts of water, along with any entrapped drug, at elevated temperatures. The required temperature change can be achieved via NIR absorption by the nanoshell, allowing the hydrogel phase change to be triggered by light, which was observed by monitoring changes in particle sizes as water was expelled from the hydrogel network. The phase change was reversible and repeatable. As a model drug, the chemotherapeutic doxorubicin was loaded into this delivery vehicle, and rapid release of doxorubicin occurred upon NIR exposure. Further, colon carcinoma cells exposed to the irradiated platform displayed nearly 3 times as much doxorubicin uptake as cells exposed to nonirradiated particles or free drug, which in turn resulted in a higher loss of cell viability. We hypothesize these effects are because the NIR-mediated heating results in a transient increase in cell membrane permeability, thus aiding in cellular uptake of the drug. PMID:26366438

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

    SciTech Connect

    Nathel, H.; Cartland, H.E.; Colston, B.W. Jr.; Everett, M.J.; Roe, J.N.

    2000-01-18

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

  7. Effects of darkening processes on surfaces of airless bodies. [light-absorbing coatings on lunar soil

    NASA Technical Reports Server (NTRS)

    Cassidy, W.; Hapke, B.

    1975-01-01

    We find the lunar darkening process could be due neither to simple addition of impact-melted glass nor to addition of devitrified glass to crushed lunar rock. There is evidence that lunar soil grains have thin, very light-absorbing coatings that mask absorption bands, seen in the reflection spectra of freshly crushed lunar rock, in the same manner as they are masked in the spectra of lunar soils. We believe the processes that produce these coatings are (1) deposition of atoms sputtered from lunar soil grains by solar wind particles and (2) deposition of vapor species vaporized from lunar soil grains by micrometeoritic impacts. We describe an apparent new type of fractionation that occurs during deposition of sputtered atoms. This fractionation favors retention of higher mass atoms over lower mass atoms, and appears to be a linear function of mass.

  8. Broadband visible-light absorber via hybridization of propagating surface plasmon.

    PubMed

    Cong, Jiawei; Zhou, Zhiqiang; Yun, Binfeng; Lv, Liu; Yao, Hongbing; Fu, Yonghong; Ren, Naifei

    2016-05-01

    We demonstrate a broadband visible-light absorber based on excitation of multiple propagating surface plasmon (PSP) resonances. The simple structure is constructed of continuous gold/silica multi-layers covered by a one-dimensional gold grating. The broadening of bandwidth arises from the inter-layer hybridization and spectral superposition of PSPs, which is predicted with the analytical coupled oscillator model and validated using the RCWA simulation. The average absorption increases with the number of gold/silica pairs and exceeds 95% over the whole visible spectrum when only five pairs are included. Moreover, results show that the absorption can be further enhanced by grading the thickness of silica layers. The presented design might enable promising applications in the fields of photovoltaic cells and thermal emitters, owing to its advantages of wideband, near-unity absorption and simple fabrication simultaneously. PMID:27128050

  9. Efficiency and stability of a phosphor-conversion white light source using a blue laser diode

    NASA Astrophysics Data System (ADS)

    Ledru, G.; Catalano, C.; Dupuis, P.; Zissis, G.

    2014-10-01

    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.

  10. OSL response bleaching of BeO samples, using fluorescent light and blue LEDs

    NASA Astrophysics Data System (ADS)

    Groppo, D. P.; Caldas, L. V. E.

    2016-07-01

    The optically stimulated luminescence (OSL) is widely used as a dosimetric technique for many applications. In this work, the OSL response bleaching of BeO samples was studied. The samples were irradiated using a beta radiation source (90Sr+90Y); the bleaching treatments (fluorescent light and blue LEDs) were performed, and the results were compared. Various optical treatment time intervals were tested until reaching the complete bleaching of the OSL response. The best combination of the time interval and bleaching type was analyzed.

  11. White-blue electroluminescence from a Si quantum dot hybrid light-emitting diode

    SciTech Connect

    Xin, Yunzi; Nishio, Kazuyuki; Saitow, Ken-ichi

    2015-05-18

    A silicon (Si) quantum dot (QD)-based hybrid inorganic/organic light-emitting diode (LED) was fabricated via solution processing. This device exhibited white-blue electroluminescence at a low applied voltage of 6 V, with 78% of the effective emission obtained from the Si QDs. This hybrid LED produced current and optical power densities 280 and 350 times greater than those previously reported for such device. The superior performance of this hybrid device was obtained by both the prepared Si QDs and the optimized layer structure and thereby improving carrier migration through the hybrid LED and carrier recombination in the homogeneous Si QD layer.

  12. Hydrogen peroxide generated by NADPH oxidase is involved in high blue-light-induced chloroplast avoidance movements in Arabidopsis

    NASA Astrophysics Data System (ADS)

    Wen, Feng; Xing, Da; Zhang, Lingrui

    2009-08-01

    One of the most important functions of blue light is to induce chloroplast movements by reducing the damage to photosynthetic machinery under excess light. Hydrogen peroxide (H2O2), generated by various environmental stimuli, can act as a signaling molecule that regulates a number of developmental processes and environmental responses. To investigate whether H2O2 is involved in high blue light-induced chloroplast avoidance movements, we use luminescence spectrometer to observe H2O2 generation with the assistance of the fluorescence probe dichlorofluorescin diacetate (H2DCF-DA). After treatment with high blue light, a large quantity of H2O2 indicated by the fluorescence intensity of DCF is produced in a dose-dependent manner in leaf strip of Arabidopsis. Enzymatic assay shows that the activity of NADPH oxidase, which is a major site for H2O2 generation, also rapidly increases in treated strips. Exogenously applied H2O2 can promote the high blue light-induced chloroplast movements. Moreover, high blue light-induced H2O2 generation can be abolished completely by addition of exogenous catalase (CAT), and partly by diphenylene iodonium (DPI) and dichlorophenyl dimethylurea (DCMU), which are an NADPH oxidase inhibitor and a blocker of electron transport chain. And subsequent chloroplast movements can be abolished by CAT and DPI, but not by DCMU. These results presented here suggested that high blue light can induce oxidative burst, and NADPH oxidase as a major producer for H2O2 is involved in blue light-induced chloroplast avoidance movements.

  13. Radiative Forcing of the Lower Stratosphere over the Arctic by Light Absorbing Particles

    NASA Technical Reports Server (NTRS)

    Baumgardner, D.; Raga, G.; Kok, G.

    2003-01-01

    Light absorbing particles (LAP), such as soot and dust, change the thermodynamic structure of the atmosphere and contribute to regional and global climate change. The lower stratosphere (LS) is particularly sensitive to the presence of LAP since the lifetime of particles in the LS may extend from months to years, in contrast to tropospheric lifetimes of at most a few days. The source of particles in the LS may be aircraft, meteorites or emissions from tropospheric sources. There has been a lack, however, of accurate, quantitative measurements made with sufficiently sensitive instruments. This limits our understanding of the origin and lifetime of aerosols in this region of the atmosphere. Here we present recent measurements in the Arctic UT/LS with a new, highly sensitive instrument that has detected black carbon (BC) mass concentrations of 20-1000 ng m(exp -3) that are 10-1000 times larger than those reported in previous studies and are at least 30 times larger than predicted masses based on fuel consumption by commercial aircraft that fly in these regions. Scattering and absorption of solar and terrestrial radiation by the particles in a layer from 8- 12 Km leads to a negative net forcing of -0.5 W sq m at the top of the atmosphere and 9C of heating in this layer during the average aerosol lifetime at these altitudes. The new measurements suggest that the influence of aircraft emissions have been underestimated or that aircraft may not be the only significant source of light absorbing particles in the UT/LS. The presence of these aerosols can cause local changes in the thermal structure of the lower stratosphere and a subsequent modification of stratosphere/tropopause exchange of gases and particles.

  14. Spatiotemporal variability of light-absorbing carbon concentration in a residential area impacted by woodsmoke.

    PubMed

    Krecl, Patricia; Johansson, Christer; Ström, Johan

    2010-03-01

    Residential wood combustion (RWC) is responsible for 33% of the total carbon mass emitted in Europe. With the new European targets to increase the use of renewable energy, there is a growing concern that the population exposure to woodsmoke will also increase. This study investigates observed and simulated light-absorbing carbon mass (MLAC) concentrations in a residential neighborhood (Lycksele, Sweden) where RWC is a major air pollution source during winter. The measurement analysis included descriptive statistics, correlation coefficient, coefficient of divergence, linear regression, concentration roses, diurnal pattern, and weekend versus weekday concentration ratios. Hourly RWC and road traffic contributions to MLAC were simulated with a Gaussian dispersion model to assess whether the model was able to mimic the observations. Hourly mean and standard deviation concentrations measured at six sites ranged from 0.58 to 0.74 microg m(-3) and from 0.59 to 0.79 microg m(-3), respectively. The temporal and spatial variability decreased with increasing averaging time. Low-wind periods with relatively high MLAC concentrations correlated more strongly than high-wind periods with low concentrations. On average, the model overestimated the observations by 3- to 5-fold and explained less than 10% of the measured hourly variability at all sites. Large residual concentrations were associated with weak winds and relatively high MLAC loadings. The explanation of the observed variability increased to 31-45% when daily mean concentrations were compared. When the contribution from the boilers within the neighborhood was excluded from the simulations, the model overestimation decreased to 16-71%. When assessing the exposure to light-absorbing carbon particles using this type of model, the authors suggest using a longer averaging period (i.e., daily concentrations) in a larger area with an updated and very detailed emission inventory. PMID:20397565

  15. Imaging spectroscopy of albedo and radiative forcing by light-absorbing impurities in mountain snow

    NASA Astrophysics Data System (ADS)

    Painter, Thomas H.; Seidel, Felix C.; Bryant, Ann C.; McKenzie Skiles, S.; Rittger, Karl

    2013-09-01

    Recent studies show that deposition of dust and black carbon to snow and ice accelerates snowmelt and perturbs regional climate and hydrologic cycles. Radiative forcing by aerosols is often neglected in climate and hydrological models in part due to scarcity of observations. Here we describe and validate an algorithm suite (Imaging Spectrometer-Snow Albedo and Radiative Forcing (IS-SnARF)) that provides quantitative retrievals of snow grain size, snow albedo, and radiative forcing by light-absorbing impurities in snow and ice (LAISI) from Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) data collected on 15 June 2011 in the Senator Beck Basin Study Area (SBBSA), SW Colorado, USA. Radiative forcing by LAISI is retrieved by the integral of the convolution of spectral irradiance with spectral differences between the spectral albedo (scaled from the observed hemispherical-directional reflectance factor (HDRF)) and modeled clean snow spectral albedo. The modeled surface irradiance at time of acquisition at test sites was 1052 W m-2 compared to 1048 W m-2 measured with the field spectroradiometer measurements, a relative difference of 0.4%. HDRF retrievals at snow and bare soil sites had mean errors relative to in situ measurements of -0.4 ± 0.1% reflectance averaged across the spectrum and root-mean-square errors of 1.5 ± 0.1%. Comparisons of snow albedo and radiative forcing retrievals from AVIRIS with in situ measurements in SBBSA showed errors of 0.001-0.004 and 2.1 ± 5.1 W m-2, respectively. A counterintuitive result was that, in the presence of light absorbing impurities, near-surface snow grain size increased with elevation, whereas we generally expect that at lower elevation the grain size would be larger.

  16. Solution structure of a cyanobacterial phytochrome GAF domain in the red-light-absorbing ground state.

    PubMed

    Cornilescu, Gabriel; Ulijasz, Andrew T; Cornilescu, Claudia C; Markley, John L; Vierstra, Richard D

    2008-11-01

    The unique photochromic absorption behavior of phytochromes (Phys) depends on numerous reversible interactions between the bilin chromophore and the associated polypeptide. To help define these dynamic interactions, we determined by NMR spectroscopy the first solution structure of the chromophore-binding cGMP phosphodiesterase/adenylcyclase/FhlA (GAF) domain from a cyanobacterial Phy assembled with phycocyanobilin (PCB). The three-dimensional NMR structure of Synechococcus OS-B' cyanobacterial Phy 1 in the red-light-absorbing state of Phy (Pr) revealed that PCB is bound to Cys138 of the GAF domain via the A-ring ethylidene side chain and is buried within the GAF domain in a ZZZsyn,syn,anti configuration. The D ring of the chromophore sits within a hydrophobic pocket and is tilted by approximately 80 degrees relative to the B/C rings by contacts with Lys52 and His169. The solution structure revealed remarkable flexibility for PCB and several adjacent amino acids, indicating that the Pr chromophore has more freedom in the binding pocket than anticipated. The propionic acid side chains of rings B and C and Arg101 and Arg133 nearby are especially mobile and can assume several distinct and energetically favorable conformations. Mutagenic studies on these arginines, which are conserved within the Phy superfamily, revealed that they have opposing roles, with Arg101 and Arg133 helping stabilize and destabilize the far-red-light-absorbing state of Phy (Pfr), respectively. Given the fact that the Synechococcus OS-B' GAF domain can, by itself, complete the Pr --> Pfr photocycle, it should now be possible to determine the solution structure of the Pfr chromophore and surrounding pocket using this Pr structure as a framework. PMID:18762196

  17. Organic optocoupler consisting of an optimized blue organic light emitting diode and an organic photoconductor

    NASA Astrophysics Data System (ADS)

    El Amrani, A.; Lucas, B.; Antony, R.

    2015-09-01

    We present an optocoupler device based on a blue organic light-emitting diode (OLED) as input unit, and a pentacene photoconductor as output unit. The optocoupler was realized on a transparent glass substrate. The luminance was found larger than 103 cd/m2 with a blue peak emission at 450 nm for the optimized ZnO (120 nm)/ITO (150 nm)/α-NPB (40 nm)/BCP (15 nm)/Alq3 (20 nm)/Al structure. The Ids-Illum/Ids-Dark current ratio, the sensitivity and the current density transfer ratio of the optocoupler are of about 7, 10-1 A/W, and 10-1, respectively. The rise as well as full times were found faster for high bias voltages. The equilibrium regime with less persistent current was reached more quickly, as evidenced by the fast current response for higher bias voltage, indicating a more favorable recombination processes of the charge carriers. The organic optocoupler with a blue OLED reveals promising results; thus, it can be investigated as a good candidates for practical uses in organic optoelectronic circuits with high bias voltages.

  18. Functional characterization of blue-light-induced responses and PHOTOTROPIN 1 gene in Welwitschia mirabilis.

    PubMed

    Ishishita, Kazuhiro; Suetsugu, Noriyuki; Hirose, Yuki; Higa, Takeshi; Doi, Michio; Wada, Masamitsu; Matsushita, Tomonao; Gotoh, Eiji

    2016-03-01

    The blue light (BL) receptor phototropin (phot) is specifically found in green plants; it regulates various BL-induced responses such as phototropism, chloroplast movement, stomatal opening, and leaf flattening. In Arabidopsis thaliana, two phototropins--phot1 and phot2--respond to blue light in overlapping but distinct ways. These BL-receptor-mediated responses enhance the photosynthetic activity of plants under weak light and minimize photodamage under strong light conditions. Welwitschia mirabilis Hook.f. found in the Namib Desert, and it has adapted to severe environmental stresses such as limiting water and strong sunlight. Although the plant has physiologically and ecologically unique features, it is unknown whether phototropin is functional in this plant. In this study, we assessed the functioning of phot-mediated BL responses in W. mirabilis. BL-dependent phototropism and stomatal opening was observed but light-dependent chloroplast movement was not detected. We performed a functional analysis of the PHOT1 gene of W. mirabilis, WmPHOT1, in Arabidopsis thaliana. We generated transgenic A. thaliana lines expressing WmPHOT1 in a phot1 phot2 double mutant background. Several Wmphot1 transgenic plants showed normal growth, although phot1 phot2 double mutant plants showed stunted growth. Furthermore, Wmphot1 transgenic plants showed normal phot1-mediated responses including phototropism, chloroplast accumulation, stomatal opening, and leaf flattening, but lacked the chloroplast avoidance response that is specifically mediated by phot2. Thus, our findings indicate that W. mirabilis possesses typical phot-mediated BL responses that were at least partially mediated by functional phototropin 1, an ortholog of Atphot1. PMID:26858202

  19. Investigations of riboflavin photolysis via coloured light in the nitro blue tetrazolium assay for superoxide dismutase activity.

    PubMed

    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. PMID:25985146

  20. Observations of Light-Absorbing Carbonaceous Aerosols in East and South Asia

    NASA Astrophysics Data System (ADS)

    Yoon, S.; Kim, S.; Choi, W.

    2013-05-01

    Light-absorbing aerosols, such as black carbon (BC), brown carbon and mineral dust, typically constitute a small fraction of ambient particle mass but can contribute to solar radiative forcing through absorption of solar radiation and heating of the absorbing aerosol layer. Besides the direct radiative effect, the heating can evaporate clouds and change the atmospheric dynamics. In this study, we investigate the optical and radiative properties of light-absorbing aerosols from ground-based and aircraft measurements in East and South Asia within the framework of UNEP Atmospheric Brown Cloud-Asia (ABC-Asia) project and Sustainable Atmosphere for the Kathmandu Valley (SusKat) campaign (December 2012 ~ February 2013). BC mass concentration, aerosol scattering and absorption coefficients measurements and radiative forcing calculations were performed at four sites: Gosan (Korea), Anmyeon (Korea), Hanimaadhoo (Maldives) and Pyramid (Nepal). No significant seasonal variations of aerosol properties, except for summer due to wet scavenging by rainfall, were observed in East Asia, whereas dramatic changes of light-absorbing aerosol properties were observed in South Asia between dry and wet monsoon periods. Although BC mass concentration in East Asia is generally higher than that observed in South Asia, BC mass concentration at Hanimaadhoo during winter dry monsoon is similar to that of East Asia. The observed solar absorption efficiency (absorption coefficient/extinction coefficient) at 550 nm at Gosan and Anmyeon is higher than that in Hanimaadhoo due to large portions of BC emission from fossil fuel combustion. Interestingly, solar absorption efficiency at Pyramid is 0.14, which is two times great than that in Hanimaadhoo and is about 40% higher than that in East Asia, though BC mass concentration at Pyramid is the lowest among four sites. Throughout the unmanned aerial vehicle experiment in Jeju, Korea during August-September 2008, long-range transport of aerosols from

  1. Effect of a light-induced pH gradient on purple-to-blue and purple-to-red transitions of bacteriorhodopsin

    SciTech Connect

    Nasuda-Kouyama, A.; Fukuda, K.; Iio, T.; Kouyama, T. )

    1990-07-24

    Bacteriorhodopsin-containing vesicles that were able to alkalize the extravesicular medium by greater than 1.5 pH units under illumination, i.e., inside-out vesicles, were reconstituted by reverse-phase evaporation with Halobacterium halobium polar lipids or exogenous phospholipids. Acid titration of a dark-adapted sample was accompanied by a color change from purple to blue (pKa = 2.5-4.5 in 0.15 M K2SO4), and alkali titration resulted in the formation of a red species absorbing maximally at 480 nm (pKa = 7 to greater than 9), the pKa values and the extents of these color changes being dependent on the nature of lipid. When a vesicle suspension at neutral or weakly acidic pH was irradiated by continuous light so that a large pH gradient was generated across the membrane, either a purple-to-blue or a purple-to-red transition took place. The light-induced purple-to-red transition was significant in an unbuffered vesicle suspension and correlated with the pH change in the extravesicular medium. The result suggests that the purple-to-red transition is driven from the extravesicular side, i.e., from the C-terminal membrane surface. In the presence of buffer molecules outside, the dominant color change induced in the light was the purple-to-blue transition, which seemed to be due to a large decrease in the intravesicular pH. But an apparently inconsistent result was obtained when the extravesicular medium was acidified by a HCl pulse, which was accompanied by a rapid color change to blue. We arrived at the following explanation: The two bR isomers, one containing all-trans-retinal and the other 13-cis-retinal, respond differently to pH changes in the extravesicular and the intravesicular medium. In this relation, full light adaptation was not achieved when the light-induced purple-to-blue transition was significant.

  2. Probing entrainment of Ostreococcus tauri circadian clock by green and blue light through a mathematical modeling approach

    PubMed Central

    Thommen, Quentin; Pfeuty, Benjamin; Schatt, Philippe; Bijoux, Amandine; Bouget, François-Yves; Lefranc, Marc

    2015-01-01

    Most organisms anticipate daily environmental variations and orchestrate cellular functions thanks to a circadian clock which entrains robustly to the day/night cycle, despite fluctuations in light intensity due to weather or seasonal variations. Marine organisms are also subjected to fluctuations in light spectral composition as their depth varies, due to differential absorption of different wavelengths by sea water. Studying how light input pathways contribute to circadian clock robustness is therefore important. Ostreococcus tauri, a unicellular picoplanktonic marine green alga with low genomic complexity and simple cellular organization, has become a promising model organism for systems biology. Functional and modeling approaches have shown that a core circadian oscillator based on orthologs of Arabidopsis TOC1 and CCA1 clock genes accounts for most experimental data acquired under a wide range of conditions. Some evidence points at putative light input pathway(s) consisting of a two-component signaling system (TCS) controlled by the only two histidine kinases (HK) of O. tauri. LOV-HK is a blue light photoreceptor under circadian control, that is required for circadian clock function. An involvement of Rhodopsin-HK (Rhod-HK) is also conceivable since rhodopsin photoreceptors mediate blue to green light input in animal circadian clocks. Here, we probe the role of LOV-HK and Rhod-HK in mediating light input to the TOC1-CCA1 oscillator using a mathematical model incorporating the TCS hypothesis. This model agrees with clock gene expression time series representative of multiple environmental conditions in blue or green light, characterizing entrainment by light/dark cycles, free-running in constant light, and resetting. Experimental and theoretical results indicate that both blue and green light can reset O. tauri circadian clock. Moreover, our mathematical analysis suggests that Rhod-HK is a blue-green light receptor and drives the clock together with LOV

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

    NASA Astrophysics Data System (ADS)

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

    2016-03-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

    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 recombination zone shifts from the cathode to the anode with increasing voltage. The exciton quenching at the anode at higher voltages leads to an efficiency roll-off. The voltage dependence of the luminous efficiency is reproduced by a drift-diffusion model under the condition that quenching of excitons at the PEDOT:PSS anode and metallic cathode is of equal strength. Experimentally, the efficiency roll-off at high voltages due to anode quenching is eliminated by the use of an electron-blocking layer between the anode and the light-emitting polymer.

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

    SciTech Connect

    Abbaszadeh, D.; Wetzelaer, G. A. H.; Nicolai, H. T.

    2014-12-14

    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 recombination zone shifts from the cathode to the anode with increasing voltage. The exciton quenching at the anode at higher voltages leads to an efficiency roll-off. The voltage dependence of the luminous efficiency is reproduced by a drift-diffusion model under the condition that quenching of excitons at the PEDOT:PSS anode and metallic cathode is of equal strength. Experimentally, the efficiency roll-off at high voltages due to anode quenching is eliminated by the use of an electron-blocking layer between the anode and the light-emitting polymer.

  6. The blue light receptor Phototropin 1 suppresses lateral root growth by controlling cell elongation.

    PubMed

    Moni, A; Lee, A-Y; Briggs, W R; Han, I-S

    2015-01-01

    We investigated the relationship between the blue light receptor phototropin 1 (phot1) and lateral root growth in Arabidopsis thaliana seedlings. Fluorescence and confocal microscopy images, as well as PHOT1 mRNA expression studies provide evidence that it is highly expressed in the elongation zone of lateral roots where auxin is accumulating. However, treatment with the auxin transport inhibitor N-1-naphthylphthalamic acid significantly reduced PHOT1 expression in this zone. In addition, PHOT1 expression was higher in darkness than in light. The total number of lateral roots was higher in the phot1 mutant than in wild-type Arabidopsis. Cells in the elongation zone of lateral roots of the phot1 mutant were longer than those of wild-type lateral roots. These findings suggest that PHOT1 plays a role(s) in elongation of lateral roots through the control of an auxin-related signalling pathway. PMID:24803136

  7. Efficient white organic light-emitting devices based on blue, orange, red phosphorescent dyes

    NASA Astrophysics Data System (ADS)

    Chen, Ping; Zhang, Liying; Duan, Yu; Xie, Wenfa; Zhao, Yi; Hou, Jingying; Liu, Shiyong; Li, Bin

    2009-03-01

    We demonstrate efficient white organic light-emitting devices (WOLEDs) based on an orange phosphorescent iridium complex bis(2-(2-fluorphenyl)-1,3-benzothiozolato-N, C2')iridium(acetylacetonate) in combination with blue phosphorescent dye bis[(4, 6-difluorophenyl)-pyridinato-N,C2)](picolinato) Ir(III) and red phosphorescent dye bis[1-(phenyl)isoquinoline] iridium (III) acetylanetonate. By introducing a thin layer of 4, 7-diphenyl-1,10-phenanthroline between blue and red emission layers, the diffusion of excitons is confined and white light can be obtained. WOLEDs with the interlayer all have a higher colour rendering index (>82) than the device without it (76). One device has the maximum current efficiency of 17.6 cd A-1 and a maximum luminance of 39 050 cd m-2. The power efficiency is 8.7 lm W-1 at 100 cd m-2. Furthermore, the device has good colour stability and the CIE coordinates just change from (0.394, 0.425) to (0.390, 0.426) with the luminance increasing from 630 to 4200 cd m-2.

  8. Repeatability and reproducibility of individual abutment impression, assessed with a blue light scanner

    PubMed Central

    Kim, Dong-Yeon; Lee, Jae-Jun; Kim, Ji-Hwan

    2016-01-01

    PURPOSE We assessed the repeatability and reproducibility of abutment teeth dental impressions, digitized with a blue light scanner, by comparing the discrepancies in repeatability and reproducibility values for different types of abutment teeth. MATERIALS AND METHODS To evaluate repeatability, impressions of the canine, first premolar, and first molar, prepared for ceramic crowns, were repeatedly scanned to acquire 5 sets of 3-dimensional data via stereolithography (STL) files. Point clouds were compared and the error sizes were measured (n=10, per type). To evaluate reproducibility, the impressions were rotated by 10-20° on the table and scanned. These data were compared to the first STL data and the error sizes were measured (n=5, per type). One-way analysis of variance was used to assess the repeatability and reproducibility of the 3 types of teeth, and Tukey honest significant differences (HSD) multiple comparison test was used for post hoc comparisons (α=.05). RESULTS The differences with regard to repeatability were 4.5, 2.7, and 3.1 µm for the canine, premolar, and molar, indicating the poorest repeatability for the canine (P<.001). For reproducibility, the differences were 6.6, 5.8, and 11.0 µm indicating the poorest reproducibility for the molar (P=.007). CONCLUSION Our results indicated that impressions of individual abutment teeth, digitized with a blue light scanner, had good repeatability and reproducibility. PMID:27350856

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

    PubMed

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

    2015-01-01

    Metasurfaces are ultrathin, two-dimensional arrays of subwavelength resonators that have been demonstrated to control the flow of light in ways that are otherwise unattainable with natural materials. These arrays are typically composed of metallic Ag or Au nanostructures shaped like split rings, nanowire pairs or nanorods (commonly referred to as meta-atoms) that are arranged to produce a collective optical response spanning an impressive range of properties, from the perfect absorption of incident light to superresolution imaging. However, metasurfaces pose major challenges in their fabrication over large areas, which can be prohibitively expensive and time consuming using conventional nanolithography techniques. Here we show that differently shaped colloidal nanocrystals can be organized into metasurface architectures using robust, scalable assembly methods. These metasurfaces exhibit extreme in-plane electromagnetic coupling that is strongly dependent on nanocrystal size, shape and spacing. Colloidal metasurfaces that display near-ideal electromagnetic absorbance can be tuned from the visible into the mid-infrared wavelengths. PMID:26099835

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

    PubMed Central

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

    2015-01-01

    Metasurfaces are ultrathin, two-dimensional arrays of subwavelength resonators that have been demonstrated to control the flow of light in ways that are otherwise unattainable with natural materials. These arrays are typically composed of metallic Ag or Au nanostructures shaped like split rings, nanowire pairs or nanorods (commonly referred to as meta-atoms) that are arranged to produce a collective optical response spanning an impressive range of properties, from the perfect absorption of incident light to superresolution imaging. However, metasurfaces pose major challenges in their fabrication over large areas, which can be prohibitively expensive and time consuming using conventional nanolithography techniques. Here we show that differently shaped colloidal nanocrystals can be organized into metasurface architectures using robust, scalable assembly methods. These metasurfaces exhibit extreme in-plane electromagnetic coupling that is strongly dependent on nanocrystal size, shape and spacing. Colloidal metasurfaces that display near-ideal electromagnetic absorbance can be tuned from the visible into the mid-infrared wavelengths. PMID:26099835

  11. From fast to slow light in a resonantly driven absorbing medium

    SciTech Connect

    Macke, Bruno; Segard, Bernard

    2010-08-15

    We theoretically study the propagation through a resonant absorbing medium of a time-dependent perturbation modulating the amplitude of a continuous wave (cw). Modeling the medium as a two-level system and linearizing the Maxwell-Bloch equations for the perturbation, we establish an exact analytical expression of the transfer function relating the Fourier transforms of the incident and transmitted perturbations. It directly gives the gain and the phase shift undergone in the medium by a harmonic modulation. For the case of a pulse modulation, it enables us to determine the transmission time of the pulse center of mass (group delay), evidencing the relative contributions of the coherent and incoherent (population) relaxations. We show that the group delay has a negative value (fast light) fixed by the coherent effects when the cw intensity is small compared to the saturation intensity and becomes positive (slow light) when this intensity increases, before attaining a maximum that cannot exceed the population relaxation time. The analytical results are completed by numerical determinations of the shape of the transmitted pulses in the different regimes.

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

    SciTech Connect

    Meglinskii, I V

    2001-12-31

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

  13. A novel violet/blue light-emitting device based on Ce2Si2O7

    PubMed Central

    Li, Ling; Wang, Shenwei; Mu, Guangyao; Yin, Xue; Ou, Kai; Yi, Lixin

    2015-01-01

    Rare-earth silicates are highly efficient materials for silicon-based light sources. Here we report a novel light-emitting device based on Ce2Si2O7. Intense violet/blue electroluminescence was observed, with a turn-on voltage of about 13 V. The violet/blue emission is attributed to 4f–5d transitions of the Ce3+ ions in Ce2Si2O7, which are formed by interfacial reaction of CeO2 and Si. Electroluminescence and photoluminescence mechanisms of the Ce2Si2O7 light-emitting device are also discussed. PMID:26564241

  14. Ocular exposure to blue-enriched light has an asymmetric influence on neural activity and spatial attention.

    PubMed

    Newman, Daniel P; Lockley, Steven W; Loughnane, Gerard M; Martins, Ana Carina P; Abe, Rafael; Zoratti, Marco T R; Kelly, Simon P; O'Neill, Megan H; Rajaratnam, Shantha M W; O'Connell, Redmond G; Bellgrove, Mark A

    2016-01-01

    Brain networks subserving alertness in humans interact with those for spatial attention orienting. We employed blue-enriched light to directly manipulate alertness in healthy volunteers. We show for the first time that prior exposure to higher, relative to lower, intensities of blue-enriched light speeds response times to left, but not right, hemifield visual stimuli, via an asymmetric effect on right-hemisphere parieto-occipital α-power. Our data give rise to the tantalising possibility of light-based interventions for right hemisphere disorders of spatial attention. PMID:27291291

  15. Ocular exposure to blue-enriched light has an asymmetric influence on neural activity and spatial attention

    PubMed Central

    Newman, Daniel P.; Lockley, Steven W.; Loughnane, Gerard M.; Martins, Ana Carina P.; Abe, Rafael; Zoratti, Marco T. R.; Kelly, Simon P.; O’Neill, Megan H.; Rajaratnam, Shantha M. W.; O’Connell, Redmond G.; Bellgrove, Mark A.

    2016-01-01

    Brain networks subserving alertness in humans interact with those for spatial attention orienting. We employed blue-enriched light to directly manipulate alertness in healthy volunteers. We show for the first time that prior exposure to higher, relative to lower, intensities of blue-enriched light speeds response times to left, but not right, hemifield visual stimuli, via an asymmetric effect on right-hemisphere parieto-occipital α-power. Our data give rise to the tantalising possibility of light-based interventions for right hemisphere disorders of spatial attention. PMID:27291291

  16. Secondary organic material formed by methylglyoxal in aqueous aerosol mimics - Part 1: Surface tension depression and light-absorbing products

    NASA Astrophysics Data System (ADS)

    Schwier, A. N.; Shapiro, E. L.; Sareen, N.; McNeill, V. F.

    2009-07-01

    We show that methylglyoxal forms light-absorbing secondary organic material in aqueous ammonium sulfate and ammonium nitrate solutions mimicking tropospheric aerosol particles. The light-absorbing products form on the order of minutes, and solution composition continues to change over several days. The results suggest an aldol condensation pathway involving the participation of the ammonium ion. Aqueous solutions of methylglyoxal, with and without inorganic salts, exhibit surface tension depression. Methylglyoxal uptake could potentially change the optical properties, climate effects, and heterogeneous chemistry of the seed aerosol over its lifetime.

  17. Light transmission through intraocular lenses with or without yellow chromophore (blue light filter) and its potential influence on functional vision in everyday environmental conditions.

    PubMed

    Owczarek, Grzegorz; Gralewicz, Grzegorz; Skuza, Natalia; Jurowski, Piotr

    2016-01-01

    In this research the factors used to evaluate the light transmission through two types of acrylic hydrophobic intraocular lenses, one that contained yellow chromophore that blocks blue light transmission and the other which did not contain that filter, were defined according to various light condition, e.g., daylight and at night. The potential influence of light transmission trough intraocular lenses with or without yellow chromophore on functional vision in everyday environmental conditions was analysed. PMID:26327154

  18. Light transmission through intraocular lenses with or without yellow chromophore (blue light filter) and its potential influence on functional vision in everyday environmental conditions

    PubMed Central

    Owczarek, Grzegorz; Gralewicz, Grzegorz; Skuza, Natalia; Jurowski, Piotr

    2016-01-01

    In this research the factors used to evaluate the light transmission through two types of acrylic hydrophobic intraocular lenses, one that contained yellow chromophore that blocks blue light transmission and the other which did not contain that filter, were defined according to various light condition, e.g., daylight and at night. The potential influence of light transmission trough intraocular lenses with or without yellow chromophore on functional vision in everyday environmental conditions was analysed. PMID:26327154

  19. 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

    PubMed Central

    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

    2014-01-01

    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/cm2 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/cm2. PMID:24381206

  20. Exposure to blue wavelength light modulates anterior cingulate cortex activation in response to 'uncertain' versus 'certain' anticipation of positive stimuli.

    PubMed

    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. PMID:26806862

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

    NASA Astrophysics Data System (ADS)

    Zhang, Chi

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

  2. 2004: Finite-Difference Time Domain Solution of Light Scattering by an Infinite Dielectric Column Immersed in an Absorbing Medium

    NASA Technical Reports Server (NTRS)

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

    2004-01-01

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

  3. Cell Wall Free Space of Cucumis Hypocotyls Contains NAD and a Blue Light-Regulated Peroxidase Activity.

    PubMed

    Shinkle, J R; Swoap, S J; Simon, P; Jones, R L

    1992-04-01

    Solutions were obtained from the cell wall free space of red light-grown cucumber (Cucumis sativus L.) hypocotyl sections by a low-speed centrifugation technique. The centrifugate contained NAD and peroxidase but no detectable cytoplasmic contamination, as indicated by the absence of the activity of glucose-6-phosphate dehydrogenase from the cell wall solution. Peroxidase activity centrifuged from the cell wall of red light-grown cucumber hypocotyl section could be resolved into at least three cathodic isoforms and two anodic isoforms by isoelectric focusing. Treatment of red light-grown cucumber seedlings with a 10-minute pulse of high-intensity blue light increased the level of cell wall peroxidase by about 60% and caused a qualitative change in the anodic isoforms of this enzyme. The increase in peroxidase activity was detectable within 25 minutes after the start of the blue light pulse, was maximal at 35 minutes, and declined to control levels by 45 minutes of irradiation. The inhibitory effect of blue light on hypocotyl elongation was more rapid than the effect of blue light on total wall peroxidase activity, leading to the conclusion that growth and peroxidase activity are not causally related. PMID:16668797

  4. Cell Wall Free Space of Cucumis Hypocotyls Contains NAD and a Blue Light-Regulated Peroxidase Activity 1

    PubMed Central

    Shinkle, James R.; Swoap, Steven J.; Simon, Patrice; Jones, Russell L.

    1992-01-01

    Solutions were obtained from the cell wall free space of red light-grown cucumber (Cucumis sativus L.) hypocotyl sections by a low-speed centrifugation technique. The centrifugate contained NAD and peroxidase but no detectable cytoplasmic contamination, as indicated by the absence of the activity of glucose-6-phosphate dehydrogenase from the cell wall solution. Peroxidase activity centrifuged from the cell wall of red light-grown cucumber hypocotyl section could be resolved into at least three cathodic isoforms and two anodic isoforms by isoelectric focusing. Treatment of red light-grown cucumber seedlings with a 10-minute pulse of high-intensity blue light increased the level of cell wall peroxidase by about 60% and caused a qualitative change in the anodic isoforms of this enzyme. The increase in peroxidase activity was detectable within 25 minutes after the start of the blue light pulse, was maximal at 35 minutes, and declined to control levels by 45 minutes of irradiation. The inhibitory effect of blue light on hypocotyl elongation was more rapid than the effect of blue light on total wall peroxidase activity, leading to the conclusion that growth and peroxidase activity are not causally related. ImagesFigure 2 PMID:16668797

  5. Tissue slides analysis using red, green, and blue LEDs as microscope light source

    NASA Astrophysics Data System (ADS)

    Pratavieira, Sebastião.; Navascues, Felipe F.; de Souza, Larissa M.; Rosa, Ramon G. T.; Kurachi, Cristina; Bagnato, Vanderlei S.

    2016-03-01

    The optical microscopy is one of the most powerful tool in the analysis of biological systems. The usual transmitted light microscope uses a white light lamp as source, what sometimes does not bring optimal results, making it necessary to introduce filters to change some illumination properties like the color temperature or the color itself. There is, of course, an intrinsic limitation on the use of filters that is the lack of an analogical control on the illumination properties and a practical limitation that depends on the number of available filters. To address this need, we developed an illumination system based on (Red, Green and Blue) RGB LEDs, were the microscope operator can control the intensity of each one independently and manually. This paper details the developed system and describes the methods used to compare quantitatively the images acquired while using the standard white light illumination and the images obtained with the developed system. To quantify the contrast, we calculated the relative population standard deviation for the intensities of each channel of the RGB image. This procedure allowed us to compare and understand the major advantages of the developed illumination system. All analysis methods have shown that a contrast enhancement can be obtained under the RGB LEDs light. The presented illumination allowed us to visualize the structures in different samples with a better contrast without the need of any additional optical filters.

  6. Large plasma-membrane depolarization precedes rapid blue-light-induced growth inhibition in cucumber

    NASA Technical Reports Server (NTRS)

    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.

  7. High color rendering index white organic light-emitting diode using levofloxacin as blue emitter

    NASA Astrophysics Data System (ADS)

    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).

  8. Why did I continue the development of blue light-emitting devices, while many others abandoned their research?

    NASA Astrophysics Data System (ADS)

    Akasaki, Isamu

    2016-03-01

    The path to the realization of GaN p-n junction blue light-emitting devices [light-emitting diodes (LEDs) and laser diodes (LDs)] is reviewed. In the early 1970s, I was strongly convinced of the prospects of GaN towards the realization of blue LEDs and short-wavelength LDs, and in 1979, I decided to adopt the metalorganic vapor phase epitaxy (MOVPE) method for the growth of GaN, which was never employed at that time, for this purpose. My group developed low-temperature (LT-) buffer layer technology based on MOVPE to drastically improve the crystal quality of GaN, which led to the realization of low-resistivity p-type GaN, its p-n junction, and the conductivity control of n-type GaN, and finally to the realization of blue light-emitting devices, such as LEDs and LDs.

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

    NASA Astrophysics Data System (ADS)

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

    2014-11-01

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

  10. Electroluminescence enhancement in blue phosphorescent organic light-emitting diodes based on different hosts

    NASA Astrophysics Data System (ADS)

    Zhang, Wei; Zhang, Fang-hui; Huang, Jin; Zhang, Mai-li; Ma, Ying

    2013-09-01

    Blue phosphorescent organic light-emitting diodes (OLEDs) are fabricated by utilizing the hole transport-type host material of 1,3-bis(carbazol-9-yl)benzene (MCP) combined with the electron transport-type host material of 1,3-bis (triphenylsilyl) benzene (UGH3) with the ratios of 1:0, 8:2 and 6:4, and doping with blue phosphorescent dopant of bis(4,6-difluorophenylpyridinato-N,C2)picolinatoiridium (FIrpic). The device with an optimum concentration proportion of MCP:UGH3 of 8:2 exhibits the maximum current efficiency of 19.18 cd/A at luminance of 35.71 cd/m2 with maintaining Commission Internationale de L'Eclairage (CIE) coordinates of (0.1481, 0.2695), which is enhanced by 35.7% compared with that of 1:0 with (0.1498, 0.2738). The improvements are attributed to the effective carrier injection and transport in emitting layer (EML) because of mixed host materials. In addition, electron and exciton are confined in the EML, and 4,4',4″-Tris(carbazol-9-yl)-triphenylamine (TCTA) and Di-[4-(N,N-ditolyl-amino)-phenyl]cyclohexane (TAPC) have the high lowest unoccupied molecular orbital (LUMO) energy level and triplet exiton energy.

  11. Phosphine Oxide Based Electron Transporting and Hole Blocking Materials for Blue Electrophosphorescent Organic Light Emitting Devices

    SciTech Connect

    Von Ruden, Amber L.; Cosimbescu, Lelia; Polikarpov, Evgueni; Koech, Phillip K.; Swensen, James S.; Wang, Liang; Darsell, Jens T.; Padmaperuma, Asanga B.

    2010-10-26

    We report the design, synthesis, thermal, and photophysical properties of two phosphine oxide based electron transport/hole blocking materials, 2,6-bis(4-(diphenylphosphoryl)phenyl)pyridine (BM-A11) and 2,4-bis(4-(diphenyl-phosphoryl)phenyl)pyridine (BM-A10) for blue electrophosphorescent organic light emitting devices (OLEDs). The use of these materials in blue OLED with iridium (III) bis[(4,6-difluorophenyl)-pyridinato-N,C2’]picolinate (Firpic) as the phosphor was demonstrated. Using the dual host device architecture with BM-A10 as the ETM yields a maximum EQE of 8.9% with a power efficiency of 21.5 lm/W (4.0V and 35 cd/m2). When BM-A11 is used as the ETM, the maximum EQE and power efficiency improves to 14.9% and 48.4 lm/W, respectively (3.0V and 40 cd/m2).

  12. Rational design of charge transport molecules for blue organic light emitting devices

    NASA Astrophysics Data System (ADS)

    Padmaperuma, Asanga; Cosimbescu, Lelia; Koech, Phillip; Polikarpov, Evgueni; Swensen, James; Gaspar, Daniel

    2012-02-01

    The efficiency and stability of blue OLEDs continue to be the primary roadblock to developing organic solid-state white lighting as well as power efficient displays. It is generally accepted that such high quantum efficiency can be achieved with the use of organometallic phosphor doped OLEDs. The transport layers can be designed to increase the carrier density as a way to reduce the drive voltage. We have developed a comprehensive library of charge transporting molecules using combination of theoretical modeling and experimental evidence. Our work focuses on using chemical structure design and computational methods to develop host, transport, emitter, and blocking materials for high efficiency blue OLEDs, along with device architectures to take advantage of these new materials. Through chemical modification of materials we are able to influence both the charge balance and emission efficiency of OLEDs, and understand the influence of the location of photon emission in OLEDs as a function of minor chemical modifications of host and electron transport materials. Design rules, structure-property relationships and results from state of the art OLEDs will be presented.

  13. Highly Efficient Blue Phosphorescent Organic Light-Emitting Diodes Employing a Host Material with Small Bandgap.

    PubMed

    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. PMID:27281124

  14. Efficient blue organic light-emitting diodes employing thermally activated delayed fluorescence

    NASA Astrophysics Data System (ADS)

    Zhang, Qisheng; Li, Bo; Huang, Shuping; Nomura, Hiroko; Tanaka, Hiroyuki; Adachi, Chihaya

    2014-04-01

    Organic light-emitting diodes (OLEDs) employing thermally activated delayed fluorescence (TADF) have emerged as cheaper alternatives to high-performance phosphorescent OLEDs with noble-metal-based dopants. However, the efficiencies of blue TADF OLEDs are still low at high luminance, limiting full-colour display. Here, we report a blue OLED containing a 9,10-dihydroacridine/diphenylsulphone derivative that has a comparable performance to today's best phosphorescent OLEDs. The device offers an external quantum efficiency of 19.5% and reduced efficiency roll-off characteristics at high luminance. Through computational simulation, we identified six pretwisted intramolecular charge-transfer (CT) molecules with small singlet-triplet CT state splitting but different energy relationships between 3CT and locally excited triplet (3LE) states. Systematic comparison of their excited-state dynamics revealed that CT molecules with a large twist angle can emit efficient and short-lifetime (a few microseconds) TADF when the emission peak energy is high enough and the 3LE state is higher than the 3CT state.

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

    NASA Astrophysics Data System (ADS)

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

    2016-06-01

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

  16. Protective effects of bilberry and lingonberry extracts against blue light-emitting diode light-induced retinal photoreceptor cell damage in vitro

    PubMed Central

    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

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

    PubMed

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

    2016-06-01

    Organic-inorganic methylammonium lead halide perovskites have recently attracted great interest emerging as promising photovoltaic materials with a high 20.8% efficiency, but lead pollution is still a problem that may hinder the development and wide spread of MAPbI3 perovskites. To reduce the use of lead, we investigated the structures, electronic and optical properties of mixed MAGexPb(1-x)I3 theoretically by using density functional theory methods at different calculation levels. Results show that the mixed Ge/Pb perovskites exhibit a monotonic decrease evolution in band energy to push the band gap deeper in the near-infrared region and have a red shift optical absorption with an increased proportion of Ge. The results also indicate that lattice distortion and spin-orbit coupling (SOC) strength play important roles in the band gap behavior of MAGexPb(1-x)I3 by affecting the bandwidths of CBM and VBM. The calculations for short circuit current density, open circuit voltage, and theoretical power conversion efficiency suggest that mixed Ge/Pb perovskite solar cells (PSCs) with efficiency over 22% are superior to MAPbI3 and MAGeI3. And notably, MAGe0.75Pb0.25I3 is a promising harmless material for solar cells absorber with the highest theoretical efficiency of 24.24%. These findings are expected to be helpful for further rational design of nontoxic light absorption layer for high-performance PSCs. PMID:27171746

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

    PubMed

    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. PMID:26841779

  19. Spectroscopic refractometer for transparent and absorbing liquids by reflection of white light near the critical angle

    SciTech Connect

    Sanchez-Perez, C.; Garcia-Valenzuela, A.

    2012-11-15

    We propose and evaluate a spectroscopic refractometer device to measure the refractive index dispersion of transparent and absorbing solutions. The angle-dependent reflectivity of a white beam of light in an internal reflection configuration around the critical angle is spectrally analyzed. The refractive index in a wavelength range from 400 nm to 900 nm is obtained from the angle-reflectivity curve around the critical angle at each wavelength. The device does not use angle scanning mechanisms, decreasing considerably the complexity of the instrument in comparison to previous proposals. As a result, the measurements are obtained relatively fast. Nevertheless, a good experimental resolution in refractive index of about {Delta}n Almost-Equal-To 10{sup -4} at all the wavelengths is achieved in the case of transparent solutions. The calibration procedure of the device is discussed in detail. We also present measurements of the refractive index dispersion of rhodamine 6G-methanol solutions, which has a strong absorption band in the visible spectra.

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

    SciTech Connect

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

    2015-01-01

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

  1. Blue light-dependent changes in loosely bound calcium in Arabidopsis mesophyll cells: an X-ray microanalysis study

    PubMed Central

    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

  2. Efficient red, green, blue and white organic light-emitting diodes with same exciplex host

    NASA Astrophysics Data System (ADS)

    Chang, Chih-Hao; Wu, Szu-Wei; Huang, Chih-Wei; Hsieh, Chung-Tsung; Lin, Sung-En; Chen, Nien-Po; Chang, Hsin-Hua

    2016-03-01

    Recently, exciplex had drawn attention because of its potential for efficient electroluminescence or for use as a host in organic light-emitting diodes (OLEDs). In this study, four kinds of hole transport material/electron transport material combinations were examined to verify the formation of exciplex and the corresponding energy bandgaps. We successfully demonstrated that the combination of tris(4-carbazoyl-9-ylphenyl)amine (TCTA) and 3,5,3‧,5‧-tetra(m-pyrid-3-yl)phenyl[1,1‧]biphenyl (BP4mPy) could form a stable exciplex emission with an adequate energy gap. Using exciplex as a host in red, green, and blue phosphorescent OLEDs with an identical trilayer architecture enabled effective energy transfer from exciplex to emitters, achieving corresponding efficiencies of 8.8, 14.1, and 15.8%. A maximum efficiency of 11.3% and stable emission was obtained in white OLEDs.

  3. Hexaminolevulinate Blue-Light Cystoscopy in a Patient with Metastatic Melanoma of the Bladder

    PubMed Central

    Wingate, Jonathan T.; Baker, Karen C.; Brand, Timothy C.

    2016-01-01

    Abstract Background: Although bladder cancer is one of the most frequently diagnosed tumors worldwide, metastatic melanoma of the bladder is a rare occurrence with only 29 cases reported in the literature. Case Presentation: We present the case of a 60-year-old male with a medical history significant for metastatic melanoma, who was referred to the urology department for gross hematuria. Transurethral resection of bladder tumor (TURBT) was performed with the assistance of hexaminolevulinate acid (HAL) with blue-light cystoscopy (BLC). Subsequent histopathologic analysis of the specimen confirmed a diagnosis of metastatic melanoma of the bladder. To our knowledge, this is the first reported case of metastatic bladder melanoma diagnosed with the assistance of HAL-BLC in a patient undergoing a TURBT. Conclusion: Although HAL-BLC is only indicated for use in the cystoscopic detection of papillary nonmuscle invasive bladder cancer, it may aid in the detection of nonconventional bladder pathologies, such as melanoma. PMID:27579421

  4. Strong blue light emission from Eu-doped SiOC prepared by magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Lin, Zhenxu; Guo, Yanqing; Wang, Xiang; Song, Chao; Song, Jie; Zhang, Yi; Huang, Rui

    2015-08-01

    The Eu-doped SiOC films were prepared by magnetron sputtering technique at a low temperature of 250°C. The effects of the Eu2O3 deposited power and post-thermal annealing temperature on the PL characteristics of the Eu-doped SiOC films were investigated. It is found that the photoluminescence intensity could be enhanced by more than tenfold by increasing the Eu2O3 deposited power from 20W to 80W. Furthermore, very bright blue light emission can be clearly observed with the naked eye in a bright room for the Eu-doped SiOC films prepared at a Eu2O3 deposited power of 80 W. The improved PL intensity is attributed to the increasing number density of europium silicate clusters as a result of the increasing Eu2O3 deposited power as well as high annealing temperatures.

  5. Red-green-blue light-emitting diodes containing fluorene-based copolymers

    NASA Astrophysics Data System (ADS)

    Drolet, Nicolas; Beaupré, Serge; Morin, Jean-François; Tao, Ye.; Leclerc, Mario

    2002-11-01

    This paper reports the fabrication and evaluation of light-emitting diodes using polyfluorene derivatives as emitter, which cover the entire visible spectral range. Depending on the composition of the copolymers, red (emission peak at 656 nm), green (488 nm) and blue (428 nm) emission was obtained without any excimer formation. The optimization of the device performances has been realized using a multilayered configuration which involves a spin-coated poly(ethylenedioxythiophene) doped with poly(styrene sulfonic acid) (PEDT-PSS) thin film on the ITO anode and an ultrathin lithium fluoride layer next to the Al cathode. These two layers improve the efficiency of the charge injection. Combining this device configuration with some additional charge-transporting molecules, luminances in the range of 50-300 cd m-2 have been obtained.

  6. Luminous efficiency enhancement in blue phosphorescent organic light-emitting diodes with an electron confinement layers

    NASA Astrophysics Data System (ADS)

    Kang, Jin Sung; Yoon, Ju-An; Yoo, Seung Il; Kim, Jin Wook; Yi, Seungjun; Zhu, Furong; Cheah, Kok Wai; Kim, Woo Young

    2015-09-01

    This study reports the results of blue phosphorescent organic light emitting diodes (PHOLEDs) employing an electron confinement layer (ECL), tris-(phenylpyrazole)iridium (Ir(ppz)3) and a hole confinement layer (HCl), 1,3,5-tris(N-phenylbenzimiazole-2-yl)benzene (TPBi). The electrical and optical characteristics of PHOLEDs with different emissive layers, including current density, luminance, and luminous efficiency, were analyzed. The thickness of the individual emissive layer was optimized, however, and the total thickness of the emitting region was kept constant at 300 Å. This work reveals that the effective electron confinement, due to a large energy level offset between the electron confinement and emitting layers, helps to improve hole-electron current balance in the emitting region. The maximum external quantum efficiency of 23.40% at 1500 cd/m2 was achieved for PHOLEDs with an ECL, which is 60% higher than the structural identical control device without ECL.

  7. Oxadiazole-containing material with intense blue phosphorescence emission for organic light-emitting diodes

    NASA Astrophysics Data System (ADS)

    Liang, Fushun; Wang, Lixiang; Ma, Dongge; Jing, Xiabin; Wang, Fosong

    2002-07-01

    2-(2-hydroxyphenyl)-5-phenyl-1, 3, 4-oxadiazole (HOXD), characteristic of excited state intramolecular proton-transfer (ESIPT), was synthesized and found to emit strong blue phosphorescence in the solid state at room temperature and at low temperature (77 K). The photoluminescent spectrum measurement in solution showed that there are two kinds of emission: fluorescence originated from the singlet state and phosphorescence derived from the triplet state in HOXD formed by ESIPT. For the photoluminescent spectrum in the solid state, only phosphorescence emission with the lifetime of 66 mus was observed. Multiple-layer light-emitting diodes with the configuration of ITO/NPB/HOXD/BCP/Alq3/Mg:Ag were fabricated using HOXD as emitter and the maximum brightness of 656 cd/m2 and the luminous efficiency of 0.14 lm/W was obtained.

  8. Blue resonant-cavity light-emitting diode with half milliwatt output power

    NASA Astrophysics Data System (ADS)

    Yeh, Pinghui S.; Chang, Chi-Chieh; Chen, Yu-Ting; Lin, Da-Wei; Wu, Chun Chia; He, Jhao Hang; Kuo, Hao-Chung

    2016-03-01

    GaN-based resonant-cavity light-emitting diode (RCLED) has a circular output beam with superior directionality than conventional LED and has power scalability by using two-dimensional-array layout. In this work, blue RCLEDs with a top reflector of approximately 50% reflectance were fabricated and characterized. An output power of more than 0.5 mW per diode was achieved before packaging under room-temperature continuous-wave (CW) operation. The full width at half maximum (FWHM) of the emission spectrum was approximately 3.5 and 4.5 nm for 10- and 20-μm-diameter devices, respectively. And the peak wavelength as well as the FWHM remained stable at various currents and temperatures.

  9. Summary of studies on the blue-green autofluorescence and light transmission of the ocular lens

    NASA Astrophysics Data System (ADS)

    Van Best, Jaap A.; Kuppens, Esmeralda V.

    1996-07-01

    This paper reviews previous work done to demonstrate the clinical relevance of the measurement of blue-green autofluorescence and light transmission of the ocular lens. These can be determined quantitatively with fluorophotometry in a few seconds. Autofluorescence and transmission values are determined in healthy volunteers, in patients with insulin-dependent diabetes mellitus, and in patients with untreated glaucoma or untreated ocular hypertension. The lens autofluorescence of healthy volunteers increased linearly and transmission decreased exponentially with age. Each year of diabetes induced an increase of autofluorescence equal to one extra year of age. Untreated glaucoma or ocular hypertension had no significant effect on lens autofluorescence and transmission. Increased autofluorescence and decreased transmission values in comparison with values of a healthy population are proved to be indicative for an increased risk of developing cataract and the clinical usefulness of these measures is demonstrated. Diabetes is a risk factor for developing cataracts while untreated glaucoma or ocular hypertension is not.

  10. Blue light emission from the heterostructured ZnO/InGaN/GaN

    PubMed Central

    2013-01-01

    ZnO/InGaN/GaN heterostructured light-emitting diodes (LEDs) were fabricated by molecular beam epitaxy and atomic layer deposition. InGaN films consisted of an Mg-doped InGaN layer, an undoped InGaN layer, and a Si-doped InGaN layer. Current-voltage characteristic of the heterojunction indicated a diode-like rectification behavior. The electroluminescence spectra under forward biases presented a blue emission accompanied by a broad peak centered at 600 nm. With appropriate emission intensity ratio, the heterostructured LEDs had potential application in white LEDs. Moreover, a UV emission and an emission peak centered at 560 nm were observed under reverse bias. PMID:23433236

  11. Characterization of the BLR1 gene encoding a putative blue-light regulator in the phytopathogenic fungus Bipolaris oryzae.

    PubMed

    Kihara, Junichi; Moriwaki, Akihiro; Tanaka, Nozomi; Ueno, Makoto; Arase, Sakae

    2007-01-01

    Bipolaris oryzae is a filamentous ascomycetous fungus that causes brown leaf spot disease in rice. We isolated and characterized BLR1, a gene that encodes a putative blue-light regulator similar to Neurospora crassa white-collar 1 (WC-1). The deduced amino acid sequence of BLR1 showed high degrees of similarity to other fungal blue-light regulator protein. Disruption of the BLR1 gene demonstrated that this gene is essential for conidial development after conidiophore formation and for near-UV radiation-enhanced photolyase gene expression. PMID:17233721

  12. Design and fabrication of adjustable red-green-blue LED light arrays for plant research

    PubMed Central

    Folta, Kevin M; Koss, Lawrence L; McMorrow, Ryan; Kim, Hyeon-Hye; Kenitz, J Dustin; Wheeler, Raymond; Sager, John C

    2005-01-01

    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. Conclusion The presentation

  13. Highly efficient blue organic light emitting devices with indium-free transparent anode on flexible substrates

    SciTech Connect

    Wang, Liang; Swensen, James S.; Polikarpov, Evgueni; Matson, Dean W.; Bonham, Charles C.; Bennett, Wendy D.; Gaspar, Daniel J.; Padmaperuma, Asanga B.

    2010-09-30

    Indium-free transparent conducting oxides may provide a lower cost solution for the transparent anode in flexible displays and energy efficient solid state lighting. We report herein a near room temperature sputtering process for generating an indium-free transparent conductive oxide (TCO) coating on a flexible substrate. Specifically, we deposited gallium-doped zinc oxide (GZO) uniformly over a 12” diameter area at room temperature on polyethylene terephthalate (PET). During deposition, the system heats to about 60oC due to the energetic sputtering conditions, without any noticeable damage to the PET substrate. The GZO films exhibit excellent physical, optical and electrical properties: roughness ~7 nm, transmittance >85% and resistivity ~ 10-3 ohm• cm. Phosphorescent blue organic light-emitting devices (OLEDs) were fabricated on these substrates with comparable performance (16% external quantum efficiency and 33 lm/W power efficiency at 1mA/cm2) to that of devices fabricated on GZO (or ITO) deposited on glass substrates, suggesting flexible GZO/PET substrates may be used instead of high-cost and rigid ITO and glass for flexible displays and solid state lighting.

  14. Evidence for Tautomerisation of Glutamine in BLUF Blue Light Receptors by Vibrational Spectroscopy and Computational Chemistry

    NASA Astrophysics Data System (ADS)

    Domratcheva, Tatiana; Hartmann, Elisabeth; Schlichting, Ilme; Kottke, Tilman

    2016-03-01

    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.

  15. Blue Light Induces a Distinct Starch Degradation Pathway in Guard Cells for Stomatal Opening.

    PubMed

    Horrer, Daniel; Flütsch, Sabrina; Pazmino, Diana; Matthews, Jack S A; Thalmann, Matthias; Nigro, Arianna; Leonhardt, Nathalie; Lawson, Tracy; Santelia, Diana

    2016-02-01

    Stomatal pores form a crucial interface between the leaf mesophyll and the atmosphere, controlling water and carbon balance in plants [1]. Major advances have been made in understanding the regulatory networks and ion fluxes in the guard cells surrounding the stomatal pore [2]. However, our knowledge on the role of carbon metabolism in these cells is still fragmentary [3-5]. In particular, the contribution of starch in stomatal opening remains elusive [6]. Here, we used Arabidopsis thaliana as a model plant to provide the first quantitative analysis of starch turnover in guard cells of intact leaves during the diurnal cycle. Starch is present in guard cells at the end of night, unlike in the rest of the leaf, but is rapidly degraded within 30 min of light. This process is critical for the rapidity of stomatal opening and biomass production. We exploited Arabidopsis molecular genetics to define the mechanism and regulation of guard cell starch metabolism, showing it to be mediated by a previously uncharacterized pathway. This involves the synergistic action of β-amylase 1 (BAM1) and α-amylase 3 (AMY3)-enzymes that are normally not required for nighttime starch degradation in other leaf tissues. This pathway is under the control of the phototropin-dependent blue-light signaling cascade and correlated with the activity of the plasma membrane H(+)-ATPase. Our results show that guard cell starch degradation has an important role in plant growth by driving stomatal responses to light. PMID:26774787

  16. Evidence for Tautomerisation of Glutamine in BLUF Blue Light Receptors by Vibrational Spectroscopy and Computational Chemistry

    PubMed Central

    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

  17. Stomatal Blue Light Response Is Present in Early Vascular Plants1[OPEN

    PubMed Central

    Doi, Michio; Kitagawa, Yuki; Shimazaki, Ken-ichiro

    2015-01-01

    Light is a major environmental factor required for stomatal opening. Blue light (BL) induces stomatal opening in higher plants as a signal under the photosynthetic active radiation. The stomatal BL response is not present in the fern species of Polypodiopsida. The acquisition of a stomatal BL response might provide competitive advantages in both the uptake of CO2 and prevention of water loss with the ability to rapidly open and close stomata. We surveyed the stomatal opening in response to strong red light (RL) and weak BL under the RL with gas exchange technique in a diverse selection of plant species from euphyllophytes, including spermatophytes and monilophytes, to lycophytes. We showed the presence of RL-induced stomatal opening in most of these species and found that the BL responses operated in all euphyllophytes except Polypodiopsida. We also confirmed that the stomatal opening in lycophytes, the early vascular plants, is driven by plasma membrane proton-translocating adenosine triphosphatase and K+ accumulation in guard cells, which is the same mechanism operating in stomata of angiosperms. These results suggest that the early vascular plants respond to both RL and BL and actively regulate stomatal aperture. We also found three plant species that absolutely require BL for both stomatal opening and photosynthetic CO2 fixation, including a gymnosperm, C. revoluta, and the ferns Equisetum hyemale and Psilotum nudum. PMID:26307440

  18. Blue-light-induced changes in Arabidopsis cryptochrome 1 probed by FTIR difference spectroscopy.

    PubMed

    Kottke, Tilman; Batschauer, Alfred; Ahmad, Margaret; Heberle, Joachim

    2006-02-28

    Cryptochromes are blue-light photoreceptors that regulate a variety of responses in animals and plants, including circadian entrainment in Drosophila and photomorphogenesis in Arabidopsis. They comprise a photolyase homology region (PHR) of about 500 amino acids and a C-terminal extension of varying length. In the PHR domain, flavin adenine dinucleotide (FAD) is noncovalently bound. The presence of a second chromophore, such as methenyltetrahydrofolate, in animal and plant cryptochromes is still under debate. Arabidopsis cryptochrome 1 (CRY1) has been intensively studied with regard to function and interaction of the protein in vivo and in vitro. However, little is known about the pathway from light absorption to signal transduction on the molecular level. We investigated the full-length CRY1 protein by Fourier transform infrared (FTIR) and UV/vis difference spectroscopy. Starting from the fully oxidized state of the chromophore FAD, a neutral flavoprotein radical is formed upon illumination in the absence of any exogenous electron donor. A preliminary assignment of the chromophore bands is presented. The FTIR difference spectrum reveals only moderate changes in secondary structure of the apoprotein in response to the photoreduction of the chromophore. Deprotonation of an aspartic or glutamic acid, probably D396, accompanies radical formation, as is deduced from the negative band at 1734 cm(-)(1) in D(2)O. The main positive band at 1524 cm(-)(1) in the FTIR spectrum shows a strong shift to lower frequencies as compared to other flavoproteins. Together with the unusual blue-shift of the absorption in the visible range to 595 nm, this clearly distinguishes the radical form of CRY1 from those of structurally highly homologous DNA photolyases. As a consequence, the direct comparison of cryptochrome to photolyase in terms of photoreactivity and mechanism has to be made with caution. PMID:16489739

  19. Comparative Study of Lettuce and Radish Grown Under Red and Blue Light-Emitting Diodes (LEDs) and White Fluorescent Lamps

    NASA Technical Reports Server (NTRS)

    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.

  20. Regulation by blue light of the fluffy gene encoding a major regulator of conidiation in Neurospora crassa.

    PubMed

    Olmedo, María; Ruger-Herreros, Carmen; Corrochano, Luis M

    2010-03-01

    The development of asexual spores, that is, the process of conidiation, in the fungus Neurospora crassa is increased by light. The fluffy (fl) gene, encoding a major regulator of conidiation, is activated by light. We describe here a detailed characterization of the regulation by blue light of fl in vegetative hyphae. This induction requires the white collar complex (WCC) while the FLD protein acts as a dark repressor of fl transcription. We show that the WCC directly regulates fl transcription in response to blue light after transiently binding the promoter. We propose that fl is repressed by FLD in vegetative mycelia and that the repression is lost after light exposure and WCC activation. The increase in fl mRNA in vegetative mycelia after light exposure, and the corresponding increase in the amount of the regulatory FL protein, should promote the activation of the conidiation pathway. The activation by light of fl provides a simple mechanism for the activation of conidiation by blue light in Neurospora that may be at work in other fungi. PMID:20026679

  1. Photomorphogenesis, photosynthesis, and seed yield of wheat plants grown under red light-emitting diodes (LEDs) with and without supplemental blue lighting

    NASA Technical Reports Server (NTRS)

    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.

  2. From Plant Infectivity to Growth Patterns: The Role of Blue-Light Sensing in the Prokaryotic World.

    PubMed

    Losi, Aba; Mandalari, Carmen; Gärtner, Wolfgang

    2014-01-01

    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. PMID:27135492

  3. From Plant Infectivity to Growth Patterns: The Role of Blue-Light Sensing in the Prokaryotic World

    PubMed Central

    Losi, Aba; Mandalari, Carmen; Gärtner, Wolfgang

    2014-01-01

    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. PMID:27135492

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

    NASA Technical Reports Server (NTRS)

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

    2002-01-01

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

  5. Anatomical features of pepper plants (Capsicum annuum L.) grown under red light-emitting diodes supplemented with blue or far-red light

    NASA Technical Reports Server (NTRS)

    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.

  6. Sugar and organic acid accumulation in guard cells of Vicia faba in response to red and blue light

    SciTech Connect

    Talbott, L.D.; Zeiger, E. )

    1993-08-01

    Changes in neutral sugar and organic acid content of guard cells were quantitated by high-performance liquid chromatography during stomatal opening in different light qualities. Sonicated Vicia faba epidermal peels were irradiated with 10 [mu]mol m[sup [minus]2] s[sup [minus]1] of blue light, a fluence rate insufficient for the activation of guard cell photosynthesis, or 125 [mu]mol m[sup [minus]2] s[sup [minus]1] of red light, in the presence of 1mM KCl, 0.1 mM CaCl[sub 2]. The low-fluence-rate blue light stimulated an average net stomatal opening of 4.7 [mu]m in 2 h, whereas the saturating fluence rate of red light stimulated an average net opening of 3.8 [mu]m in 2 h. Under blue light, the malate content of guard cells increased to 173% of the initial level during the first 30 min of opening and declined as opening continued. Sucrose levels continuously rose throughout the blue light-stimulated opening, reaching 215% of the initial level after 2 h. The starch hydrolysis products maltose and maltotriose remained elevated at all times. Under red light, guard cells showed very little increase in organic acid or maltose levels, whereas sucrose levels increased to 208% of the initial level after 2 h. Total measured organic metabolite concentrations were correlated with stomatal apertures in all cases except where substantial malate increases occurred. These results support the hypothesis that light quality modulates alternative mechanisms of osmotic accumulation guard cells, including potassium uptake, photosynthetic sugar production, and starch breakdown. 29 refs., 5 figs., 2 tab.

  7. Blue Light-induced Dimerization of Monomeric Aureochrome-1 Enhances Its Affinity for the Target Sequence*

    PubMed Central

    Hisatomi, Osamu; Nakatani, Yoichi; Takeuchi, Ken; Takahashi, Fumio; Kataoka, Hironao

    2014-01-01

    Aureochrome-1 (AUREO1) is a blue light (BL) receptor that mediates the branching response in stramenopile alga, Vaucheria frigida. AUREO1 contains a basic leucine zipper (bZIP) domain in the central region and a light-oxygen-voltage sensing (LOV) domain at the C terminus, and has been suggested to function as a light-regulated transcription factor. We have previously reported that preparations of recombinant AUREO1 contained the complete coding sequence (full-length, FL) and N-terminal truncated protein (ZL) containing bZIP and LOV domains, and suggested that wild-type ZL (ZLwt2) was in a dimer form with intermolecular disulfide linkages at Cys162 and Cys182 (Hisatomi, O., Takeuchi, K., Zikihara, K., Ookubo, Y., Nakatani, Y., Takahashi, F., Tokutomi, S., and Kataoka, H. (2013) Plant Cell Physiol. 54, 93–106). In the present study, we report the photoreactions, oligomeric structures, and DNA binding of monomeric cysteine to serine-mutated ZL (ZLC2S), DTT-treated ZL (DTT-ZL), and FL (DTT-FL). Recombinant AUREO1 showed similar spectral properties and dark regeneration kinetics to those of dimeric ZLwt2. Dynamic light scattering and size exclusion chromatography revealed that ZLC2S and DTT-ZL were monomeric in the dark state. Dissociation of intermolecular disulfide bonds of ZLwt2 was in equilibrium with a midpoint oxidation-redox potential of approximately −245 ± 15 mV. BL induced the dimerization of monomeric ZL, which subsequently increased its affinity for the target sequence. Also, DTT-FL was monomeric in the dark state and underwent BL-induced dimerization, which led to formation of the FL2·DNA complex. Taken together, our results suggest that monomeric AUREO1 is present in vivo, with dimerization playing a key role in its role as a BL-regulated transcription factor. PMID:24790107

  8. Multi-watt power blue light generation by intracavity sum- frequency-mixing in KTiOPO4 crystal.

    PubMed

    Haiyong, Zhu; Ge, Zhang; Chenghui, Huang; Yong, Wei; Lingxiong, Huang; Zhenqiang, Chen

    2008-03-01

    In this paper, a high power blue laser at 447 nm was obtained by intracavity sum-frequency-mixing of a diode-side-pumped Q-switched Nd:YAlO(3)(Nd:YAP) laser operating at 1341.4 nm. A type-I critical phase matching LiB(3)O(5) (LBO) crystal and type-II critical phase matching KTiOPO(4) (KTP) crystal were used for second harmonic generation and third harmonic generation, respectively. The phase matching condition of the KTP crystal was researched. The results show that the KTP has superiority in intracavity sum-frequency-mixing blue light generation. 4.76 W blue light output was achieved at 4.6 kHz with the pulse width of 190ns. The fluctuation of output power was better than 3% at the output power of 4.76 W during half an hour. PMID:18542384

  9. Color-stable and efficient stacked white organic light-emitting devices comprising blue fluorescent and orange phosphorescent emissive units

    NASA Astrophysics Data System (ADS)

    Chen, Ping; Xue, Qin; Xie, Wenfa; Duan, Yu; Xie, Guohua; Zhao, Yi; Hou, Jingying; Liu, Shiyong; Zhang, Liying; Li, Bin

    2008-10-01

    We have demonstrated two kinds of stacked white organic light-emitting diodes (WOLEDs) employing tri(8-hydroxyquinoline) aluminum:20 wt %Mg/MoO3 as charge generation layer. White light emission can be obtained by mixing blue fluorescence and orange phosphorescence. Stacked WOLED with individual blue fluorescent and orange phosphorescent emissive units has better color stability and higher efficiency than that with double white emissive units, which is attributed to the avoidance of the movement of charges recombination zone and elimination of the Dexter energy transfer between blue and orange emission layers occurring in the latter. The efficiency of the stacked WOLED is 35.9 cd/A at 1000 cd/m2.

  10. Removal of reactive blue 19 dye by sono, photo and sonophotocatalytic oxidation using visible light.

    PubMed

    Khan, Muhammad Abdul Nasir; Siddique, Maria; Wahid, Fazli; Khan, Romana

    2015-09-01

    An efficient sonophotocatalytic degradation of reactive blue 19 (RB 19) dye was successfully carried out using sulfur-doped TiO2 (S-TiO2) nanoparticles. The effect of various treatment processes that is sonolysis, photolysis, catalysis, sonocatalysis, photocatalysis, and sonophotocatalysis were investigated for RB 19 removal. S-TiO2 were synthesized in 1, 3 and 5 wt.% of sulfur by sol-gel process and characterized by X-ray diffraction (XRD) and scanning electron microscopy coupled with energy dispersive X-ray (SEM-EDX), UV-Visible diffuse reflectance spectra (DRS). The results confirm anatase phase of TiO2, porous agglomerate structure, and a red shift in the absorbance spectra of S-TiO2. The dye degradation was studied by using UV-Vis spectrophotometer at λ max=594 nm. The reaction parameters such as pH, catalyst dosage, initial dye concentration, ultrasonic power and effect of sulfur doping in different weight percent were studied to find out the optimum degradation conditions. Optimum conditions were found as: S-TiO2=5 wt.%, catalyst (S-TiO2 5 wt.%)=50mg, RB 19 solution concentration=20 mg L(-1), pH=3, ultrasound power=100 and operating temperature=25°C. The response of 5 wt.% S-TiO2 was found better than 1 and 3 wt.% S-TiO2 and other forms TiO2. The sonophotocatalysis process was superior to other methods. During this process the ultrasound cavitation and photocatalysis water splitting takes place which leads to the generation of OH. As reveled by the GCMS results the reactive blue 19 (20 mg L(-1)) was degraded to 90% within 120 min. The S-TiO2 sonophotocatalysis system was studied for the first time for dye degradation and was found practicable, efficient and cost effective for the degradation of complex and resistant dyes such as RB19. PMID:25899438

  11. Chronic Artificial Blue-Enriched White Light Is an Effective Countermeasure to Delayed Circadian Phase and Neurobehavioral Decrements

    PubMed Central

    Najjar, Raymond P.; Wolf, Luzian; Taillard, Jacques; Schlangen, Luc J. M.; Salam, Alex

    2014-01-01

    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. PMID:25072880

  12. Chronic artificial blue-enriched white light is an effective countermeasure to delayed circadian phase and neurobehavioral decrements.

    PubMed

    Najjar, Raymond P; Wolf, Luzian; Taillard, Jacques; Schlangen, Luc J M; Salam, Alex; Cajochen, Christian; Gronfier, Claude

    2014-01-01

    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. PMID:25072880

  13. Isolation, expression, and characterization of blue light receptor AUREOCHROME gene from Saccharina japonica (Laminariales, Phaeophyceae).

    PubMed

    Deng, Yunyan; Yao, Jianting; Fu, Gang; Guo, Hui; Duan, Delin

    2014-04-01

    Photosynthetic stramenopile have chloroplasts of secondary endosymbiotic origin and are significant as aquatic primary productivity and biomass production. In marine environments, many photosynthetic stramenopiles utilize blue light to regulate growth, development, and organelle movement. Aureochrome (AUREO) is a new type blue light photoreceptor specific in photosynthetic stramenopiles. Previously, several AUREO orthologs were reported in genomes of stramenopile members, but the full-length cDNA sequences were completed only in Vaucheria frigida (Xanthophyceae), Fucus distichus (Phaeophyceae), and Ochromonas danica (Chrysophyceae). In this study, the full-length cDNA of AUREO from Saccharina japonica (designated as SjAUREO) was isolated based on homologous cloning and the rapid amplification of cDNA ends (RACE). It characterized by the full length of 1,013 bp with an open reading frame of 612 bp, which encoded a polypeptide of 203 amino acids with predicted molecular weight of 23.08 kDa and theoretical isoelectric point of 7.63. The deduced amino acid sequence of SjAUREO contained one N-terminal basic region/leucine zipper (bZIP) transcription regulation domain and a single light-, oxygen-, or voltage-sensitive (LOV) domain near the C-terminus. Homologous analysis showed that SjAUREO shared 40-92 % similarities with those of other photosynthetic stramenopiles. Phylogenetic analysis revealed close phylogenetic affinity between SjAUREO and AUREO4 of brown alga Ectocarpus siliculosus. Real-time PCR detection revealed that the SjAUREO transcription was markedly increased under BL exposure and dramatically upregulated in the 1-month juvenile sporophyte than those in the 2 and 3-month materials, which indirectly reflected the SjAUREO associated with the BL-mediated photomorphogenesis during the growth and early development of juvenile sporophytes. In vitro expression showed one distinct band existed at ∼27 kDa, and western blot detection proved that it was

  14. A comparison of the second harmonic generation from light-adapted, dark-adapted, blue, and acid purple membrane.

    PubMed

    Chen, Z; Sheves, M; Lewis, A; Bouevitch, O

    1994-09-01

    The second order nonlinear polarizability and dipole moment changes upon light excitation of light-adapted bacteriorhodopsin (BR), dark-adapted BR, blue membrane, and acid purple membrane have been measured by second harmonic generation. Our results indicate that the dipole moment changes of the retinal chromophore, delta mu, are very sensitive to both the chromophore structure and protein/chromophore interactions. Delta mu of light-adapted BR is larger than that of dark-adapted BR. The acid-induced formation of the blue membrane results in an increase in the delta mu value, and formation of acid purple membrane, resulting from further reduction of pH to 0, returns the delta mu to that of light-adapted BR. The implications of these findings are discussed. PMID:7811928

  15. A comparison of the second harmonic generation from light-adapted, dark-adapted, blue, and acid purple membrane.

    PubMed Central

    Chen, Z; Sheves, M; Lewis, A; Bouevitch, O

    1994-01-01

    The second order nonlinear polarizability and dipole moment changes upon light excitation of light-adapted bacteriorhodopsin (BR), dark-adapted BR, blue membrane, and acid purple membrane have been measured by second harmonic generation. Our results indicate that the dipole moment changes of the retinal chromophore, delta mu, are very sensitive to both the chromophore structure and protein/chromophore interactions. Delta mu of light-adapted BR is larger than that of dark-adapted BR. The acid-induced formation of the blue membrane results in an increase in the delta mu value, and formation of acid purple membrane, resulting from further reduction of pH to 0, returns the delta mu to that of light-adapted BR. The implications of these findings are discussed. PMID:7811928

  16. Investigations of blue light-induced reactive oxygen species from flavin mononucleotide on inactivation of E. coli.

    PubMed

    Liang, Ji-Yuan; Cheng, Chien-Wei; Yu, Chin-Hao; Chen, Liang-Yü

    2015-02-01

    The micronutrients in many cellular processes, riboflavin, flavin mononucleotide (FMN), and flavin adenine dinucleotide (FAD) are photo-sensitive to UV and visible light for generating reactive oxygen species (ROS). Produced from phosphorylation of riboflavin, FMN is more water-soluble and rapidly transformed into free riboflavin after ingestion. This study investigated the application of visible blue light with FMN to development of an effective antimicrobial treatment. The photosensitization of bacterial viability with FMN was investigated by light quality, intensity, time, and irradiation dosage. The blue light-induced photochemical reaction with FMN could inactivate Escherichiacoli by the generated ROS in damaging nucleic acids, which was validated. This novel photodynamic technique could be a safe practice for photo-induced inactivation of environmental microorganism to achieve hygienic requirements in food processing. PMID:25617617

  17. Chemical Magnetoreception: Bird Cryptochrome 1a Is Excited by Blue Light and Forms Long-Lived Radical-Pairs

    PubMed Central

    Liedvogel, Miriam; Maeda, Kiminori; Henbest, Kevin; Schleicher, Erik; Simon, Thomas; Timmel, Christiane R.; Hore, P. J.; Mouritsen, Henrik

    2007-01-01

    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. PMID:17971869

  18. AZO/Ag/AZO anode for resonant cavity red, blue, and yellow organic light emitting diodes

    NASA Astrophysics Data System (ADS)

    Gentle, A. R.; Yambem, S. D.; Burn, P. L.; Meredith, P.; Smith, G. B.

    2016-06-01

    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.

  19. Photodynamic inactivation of methylene blue and tungsten-halogen lamp light against food pathogen Listeria monocytogenes.

    PubMed

    Lin, Shao-ling; Hu, Jia-miao; Tang, Shu-shu; Wu, Xi-yang; Chen, Zhen-qiang; Tang, Shu-ze

    2012-01-01

    The aim of this study was to verify the bactericidal effect and the damage of photodynamic inactivation (PDI) using methylene blue (MB) and tungsten-halogen lamp over Listeria monocytogenes via atomic force microscopy, absorption spectrophotometry, agarose gel electrophoresis, real-time PCR and SDS-PAGE. The obtained data indicated that the viability of L. monocytogenes was ca 7-log reduced by illumination with 10 min tungsten-halogen lamp light under the presence of 0.5 μg mL(-1) MB, and this bactericidal activity against L. monocytogenes of PDI increased proportionally to the concentration of MB and the duration of irradiation. Moreover, after irradiation with MB and visible light, the leakage of intracellular contents was estimated by spectrophotometer at OD(260) and OD(280), which correlated with morphological alterations. Furthermore, genomic DNA cleavage and protein degradation were also detected after PDI treatment. Consequently, breakage of the membrane, damage of the genomic DNA and degradation of bacterial proteins may play an important role in the mechanisms involved in PDI-MB bactericidal activity on L. monocytogenes. PMID:22469298

  20. Hydrogel nanocomposites: a potential UV/blue light filtering material for ophthalmic lenses.

    PubMed

    Bozukova, Dimitriya; Pagnoulle, Christophe; De Pauw-Gillet, Marie-Claire; Vertruyen, Bénédicte; Jérôme, Robert; Jérôme, Christine

    2011-01-01

    Poly(2-hydroxyethyl methacrylate-co-methyl methacrylate) (poly(HEMA-co-MMA)) and ZnS hydrogel nanocomposites were prepared and characterized. The chemical composition of the inorganic nanoparticles was confirmed by X-ray diffraction, and the homogeneity of their distribution within the hydrogel was assessed by transmission electron microscopy. The influence of the content of ZnS nanoparticles on the optical performances of the nanocomposites was investigated by UV-Vis spectroscopy. The ability of the hydrogel nanocomposites to filter the hazardous UV light and part of the blue light was reported, which makes them valuable candidates for ophthalmic lens application. In contrast to the optical properties, the thermo-mechanical properties of neat poly(HEMA-co-MMA) hydrogels were found to be largely independent of filling by ZnS nanoparticles (≤2 mg/ml co-monomer mixture). Finally, in vitro cell adhesion test with lens epithelial cells (LECs), extracted from porcine lens crystalline capsule, showed that ZnS had no deleterious effect on the biocompatibility of neat hydrogels, at least at low content. PMID:20961497

  1. Characterization of a FEL lamp type source towards a blue light irradiance intercomparison in medical field

    NASA Astrophysics Data System (ADS)

    Ferreira, A. F. G., Jr.

    2011-01-01

    This work presents the characterization of modified FEL 1000W lamp housing to be used as a transference standard in the blue light irradiance intercomparison. It aims to support the metrological issues of medical equipment manufactures concerning the phototherapy treatment stated on the standard NBR/IEC 60601-2-50. The light source characterization consists of lamp seasoning, lamp short-term drift and lamp irradiance relative spatial distribution at the plane of measurement. The lamp seasoning is performed by a software developed in LabView® which measures the lamp voltage, current and irradiance at each 5 minutes during 25 hours of seasoning. The lamp short-term drift is evaluated by measuring the lamp irradiance during a sequence of 2 hours of lamp using. The lamp irradiance relative spatial distribution is verified using a radiometer head with a reduced aperture attached to an YZ positing system at each 2 mm in an interval of 24 mm. The lamp presented variation of about 0.1%/h during seasoning. Short-term drift for the lamp after a warm-up of 20 minutes was less than 0.9% for series of 4 lamp switching cycles. Lamp irradiance relative spatial distribution showed a variation of ±1.25% for a circular diameter of 20 mm. The overall uncertainty for lamp irradiance was 3.65%.

  2. Source Attribution of Light-absorbing Aerosols in Arctic Snow (Invited)

    NASA Astrophysics Data System (ADS)

    Hegg, D.; Warren, S. G.; Grenfell, T. C.; Doherty, S. J.; Larson, T. V.; Clarke, A. D.

    2010-12-01

    Light-absorbing aerosols (LAA) deposited on the arctic snow pack, in particular black carbon (BC), contribute appreciably to the arctic radiation budget and their reduction has been suggested as a means to attenuate warming in the arctic. Effective prediction and mitigation of Arctic snow LAA requires that the sources of the LAA be elucidated. To this end, receptor modeling in the form of Positive Matrix Factorization (PMF) has been exercised on a data set of chemical concentrations in snow of various species (including inorganic and organic acids, carbohydrates and selected other organics as well as LAA) derived from an extensive set of snow samples from locations in Russia (including Siberia), Canada, Greenland, the Arctic Ocean and Svalbard. The data were obtained in three distinct periods: spring of 2007, spring of 2008, and spring of 2009. Data from each period were analyzed separately (note that the Svalbard data were analyzed only recently and were not included in the published 2007 analysis). Aerosol light absorption was determined spectrophotometrically at multiple wavelengths on filters through which melted snow was filtered. Based on the Angstrom exponent of the light absorption, partitioning of the absorption between BC and other LAA species was estimated. Statistics of the LAA concentrations for the Arctic as a whole and the geographic distribution of BC and other LAA species are presented. PMF analysis of the filtrate and filters from the 2007 data set from western Siberia, the Canadian lower arctic and Greenland revealed four factors or sources: two distinct biomass burning sources, a pollution source and a marine source. The first three of these were responsible for essentially all of the black carbon, with the two biomass sources together accounting for > 90% of the black carbon. Geographically, the biomass sources were dominant for all regions except the Arctic Ocean near the North Pole. For the 2008 and 2009 data sets, from eastern Siberia and

  3. Enabling low amounts of YAG:Ce3+ to convert blue into white light with plasmonic Au nanoparticles

    NASA Astrophysics Data System (ADS)

    Hussain, Talib; Zhong, Liubiao; Danesh, Mohammad; Ye, Huiqi; Liang, Ziqiang; Xiao, Dong; Qiu, Cheng-Wei; Lou, Chaogang; Chi, Lifeng; Jiang, Lin

    2015-06-01

    We report a new strategy to directly attach Au nanoparticles onto YAG:Ce3+ phosphor via a chemical preparation method, which yields efficient and quality conversion of blue to yellow light in the presence of a low amount of phosphor. Photoluminescent intensity and quantum yield of YAG:Ce3+ phosphor are significantly enhanced after Au nanoparticle modification, which can be attributed to the strongly enhanced local surface electromagnetic field of Au nanoparticles on the phosphor particle surface. The CIE color coordinates shifted from the blue light (0.23, 0.23) to the white light region (0.30, 0.33) with a CCT value of 6601 K and a good white light CRI value of 78, which indicates that Au nanoparticles greatly improve the conversion efficiency of low amounts of YAG:Ce3+ in WLEDs.We report a new strategy to directly attach Au nanoparticles onto YAG:Ce3+ phosphor via a chemical preparation method, which yields efficient and quality conversion of blue to yellow light in the presence of a low amount of phosphor. Photoluminescent intensity and quantum yield of YAG:Ce3+ phosphor are significantly enhanced after Au nanoparticle modification, which can be attributed to the strongly enhanced local surface electromagnetic field of Au nanoparticles on the phosphor particle surface. The CIE color coordinates shifted from the blue light (0.23, 0.23) to the white light region (0.30, 0.33) with a CCT value of 6601 K and a good white light CRI value of 78, which indicates that Au nanoparticles greatly improve the conversion efficiency of low amounts of YAG:Ce3+ in WLEDs. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr01038a

  4. Quantum-dot blue light emitting diodes utilizing organic/inorganic hybrid structures

    NASA Astrophysics Data System (ADS)

    Wu, Feifei; Hu, Lian; Zhang, Bingpo; Li, Ruifeng; Wu, Huizhen

    2015-02-01

    We report blue color quantum-dot light-emitting diodes (QDLEDs) using an organic-inorganic hybrid structure and CdZnS-ZnS core-shell quantum-dot emitters. In the device organic ploy(3,4-ethylenedioxythiophene):ploy(styrene sulfonate) (PEDOT:PSS) and NN‧-bis(3-methylphenyl)-NN‧-bis(phenyl)-99-spiro-bifluorene (TPD) thin films are respectively used as the hole-injection layer (HIL) and the hole-transporting layer (HTL), and an inorganic ZnSnO thin film is used as the electron-transporting layer (ETL). In the blue QDLEDs, the function of the TPD-HTL is explored and it is found that the device employing a TPD-HTL exhibits much better optical characteristics compared with that having an identical device layout but without the TPD-HTL. The TPD HTL acts as a transition layer and offers a ladder for the injected holes from PEDOT:PSS to the QDs, leading to an more efficient hole injection. It is further found that the intensity ratio between surface-state emission (SSE) and band-edge emission (BEE) (RS/B) of the two devices shows significant difference at high bias voltages. The SSE becomes more prominent at higher bias voltage in the QDLEDs due to the imbalance injection of holes and electrons. The injected holes firstly encounter the excessive electrons accumulated at the surface of the charged QDs, thus the probability of hole-electron recombination at the QDs surface is greatly enhanced at high bias voltages.

  5. 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

    PubMed Central

    Lieverse, Ritsaert; Nielen, Marjan MA; Veltman, Dick J; Uitdehaag, Bernard MJ; van Someren, Eus JW; Smit, Jan H; Hoogendijk, Witte JG

    2008-01-01

    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 reduces nonseasonal

  6. Light-absorbing aldol condensation products in acidic aerosols: Spectra, kinetics, and contribution to the absorption index

    NASA Astrophysics Data System (ADS)

    Nozière, Barbara; Esteve, William

    The radiative properties of aerosols that are transparent to light in the near-UV and visible, such as sulfate aerosols, can be dramatically modified when mixed with absorbing material such as soot. In a previous work we had shown that the aldol condensation of carbonyl compounds produces light-absorbing compounds in sulfuric acid solutions. In this work we report the spectroscopic and kinetic parameters necessary to estimate the effects of these reactions on the absorption index of sulfuric acid aerosols in the atmosphere. The absorption spectra obtained from the reactions of six different carbonyl compounds (acetaldehyde, acetone, propanal, butanal, 2-butanone, and trifluoroacetone) and their mixtures were compared over 190-1100 nm. The results indicated that most carbonyl compounds should be able to undergo aldol condensation. The products are oligomers absorbing light in the 300-500 nm region where few other compounds absorb, making them important for the radiative properties of aerosols. Kinetic experiments in 96-75 wt% H 2SO 4 solutions and between 273 and 314 K gave an activation energy for the rate constant of formation of the aldol products of acetaldehyde of -(70±15) kJ mol -1 in 96 wt% solution and showed that the effect of acid concentration was exponential. A complete expression for this rate constant is proposed where the absolute value in 96 wt% H 2SO 4 and at 298 K is scaled to the Henry's law coefficient for acetaldehyde and the absorption cross-section for the aldol products assumed in this work. The absorption index of stratospheric sulfuric acid aerosols after a 2-year residence time was estimated to 2×10 -4, optically equivalent to a content of 0.5% of soot and potentially significant for the radiative forcing of these aerosols and for satellite observations in channels where the aldol products absorb.

  7. Acne phototherapy using UV-free high-intensity narrow-band blue light: a three-center clinical study

    NASA Astrophysics Data System (ADS)

    Shalita, Alan R.; Harth, Yoram; Elman, Monica; Slatkine, Michael; Talpalariu, Gerry; Rosenberg, Yitzhak; Korman, Avner; Klein, Arieh

    2001-05-01

    Propionibacterium. acnes is a Gram positive, microaerophilic bacterium which takes a part in the pathogenesis of inflammatory acne. P. acnes is capable to produce high amounts endogenic porphyrins with no need of any trigger molecules. Light in the violet-blue range (407-420 nm) has been shown to exhibit a phototoxic effect on Propionibacterium acnes when irradiated in vitro. The purpose of our study was to test the clinical effects of a high intensity narrowband blue light source on papulo pustular acne. A total of 35 patients in 3 centers were treated twice a week with a high intensity metal halide lamp illuminating the entire face (20x20 cm2) or the back with visible light in the 407-420 nm range at an intensity of 90 mW/cm2 (CureLight Ltd.) for a total of 4 weeks. UV is totally cut off. In each treatment the patient was exposed to light for 8-15 minutes. After 8 treatments, 80% of the patients with mild to moderate papulo-pustular acne showed significant improvement at reducing the numbers of non- inflammatory, inflammatory and total facial lesions. Inflammatory lesion count decrease by a mean of 68%. No side effects to the treatment were noticed. In conclusion, full face or back illumination with the high intensity pure blue light we used exhibits a rapid significant decrease in acne lesions counts in 8 biweekly treatments.

  8. Poly(vinylpyrrolidone) supported copper nanoclusters: glutathione enhanced blue photoluminescence for application in phosphor converted light emitting devices

    NASA Astrophysics Data System (ADS)

    Wang, Zhenguang; Susha, Andrei S.; Chen, Bingkun; Reckmeier, Claas; Tomanec, Ondrej; Zboril, Radek; Zhong, Haizheng; Rogach, Andrey L.

    2016-03-01

    Poly(vinylpyrrolidone) supported Cu nanoclusters were synthesized by reduction of Cu(ii) ions with ascorbic acid in water, and initially showed blue photoluminescence with a quantum yield of 8%. An enhancement of the emission quantum yield has been achieved by treatment of Cu clusters with different electron-rich ligands, with the most pronounced effect (photoluminescence quantum yield of 27%) achieved with glutathione. The bright blue emission of glutathione treated Cu NCs is fully preserved in the solid state powder, which has been combined with commercial green and red phosphors to fabricate down-conversion white light emitting diodes with a high colour rendering index of 92.Poly(vinylpyrrolidone) supported Cu nanoclusters were synthesized by reduction of Cu(ii) ions with ascorbic acid in water, and initially showed blue photoluminescence with a quantum yield of 8%. An enhancement of the emission quantum yield has been achieved by treatment of Cu clusters with different electron-rich ligands, with the most pronounced effect (photoluminescence quantum yield of 27%) achieved with glutathione. The bright blue emission of glutathione treated Cu NCs is fully preserved in the solid state powder, which has been combined with commercial green and red phosphors to fabricate down-conversion white light emitting diodes with a high colour rendering index of 92. Electronic supplementary information (ESI) available: The optical spectra of control experiments for Cu NC synthesis, optimization of the reaction conditions, and spectra for LEDs chips and blue LEDs. See DOI: 10.1039/c6nr00806b

  9. Synthesis of oxocarbon-encapsulated gold nanoparticles with blue-shifted localized surface plasmon resonance by pulsed laser ablation in water with CO2 absorbers.

    PubMed

    Del Rosso, T; Rey, N A; Rosado, T; Landi, S; Larrude, D G; Romani, E C; Junior, F L Freire; Quinteiro, S M; Cremona, M; Aucelio, R Q; Margheri, G; Pandoli, O

    2016-06-24

    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. PMID:27171728

  10. Synthesis of oxocarbon-encapsulated gold nanoparticles with blue-shifted localized surface plasmon resonance by pulsed laser ablation in water with CO2 absorbers

    NASA Astrophysics Data System (ADS)

    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.

  11. Sleep Disturbances Are Related to Decreased Transmission of Blue Light to the Retina Caused by Lens Yellowing

    PubMed Central

    Kessel, Line; Siganos, Galatios; Jørgensen, Torben; Larsen, Michael

    2011-01-01

    Study Objectives: 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 lens, and this may impair the photoentrainment of circadian rhythm leading to sleep disorders. The aim of the study was to examine the association between lens aging and sleep disorders. Design: Cross-sectional population based study. Setting: The study was performed at the Research Center for Prevention and Health, Glostrup Hospital, Denmark and at the Department of Ophthalmology, Herlev Hospital, Denmark. Participants: An age- and sex-stratified sample of 970 persons aged 30 to 60 years of age drawn from a sample randomly selected from the background population. Interventions: Not applicable. Measurements and Results: Sleep disturbances were evaluated by a combination of questionnaire and the use of prescription sleeping medication. Lens aging (transmission and yellowing) was measured objectively by lens autofluorometry. The risk of sleep disturbances was significantly increased when the transmission of blue light to the retina was low, even after correction for the effect of age and other confounding factors such as smoking habits, diabetes mellitus, gender, and the risk of ischemic heart disease (P < 0.0001). Conclusions: Filtration of blue light by the aging lens was significantly associated with an increased risk of sleep disturbances. We propose that this is a result of disturbance of photoentrainment of circadian rhythms. Citation: Kessel L; Siganos G; Jørgensen T; Larsen M. Sleep disturbances are related to decreased transmission of blue light to the retina caused by lens yellowing. SLEEP 2011;34(9):1215-1219. PMID:21886359

  12. Linearity evaluation in absorbance detection: the use of light-emitting diodes for on-capillary detection in capillary electrophoresis.

    PubMed

    Macka, M; Andersson, P; Haddad, P R

    1996-12-01

    A model which takes into account both stray light and polychromatic light was used to predict and evaluate linearity in on-capillary detection in capillary electrophoresis (CE). According to the model the stray light is the major factor which determines linearity under typical CE operating conditions. By calculating theoretical absorbance versus concentration plots, the influence of different levels of stray light and polychromatic light on linearity is demonstrated. Experimentally, six light-emitting diodes (LEDs) in the range from 563 to 654 nm were examined as light sources for on-capillary detection in CE. Fitting theoretical curves to measured linearity plots enabled determination of the values of both effective path length and stray light for a particular detection system. The detector linearity for the four LEDs was compared to mercury and tungsten lamps used with interference filters. For potassium permanganate as the test compound, the linear range for a 563 nm LED was two times greater than that for a mercury lamp operated at 546 nm. The relatively poor linearity of the mercury lamp detector is explained by its high level of stray light. The noise of the LED563-based detector was the same as for the mercury lamp, whereas the other LEDs of higher light intensity gave approximately half the noise of the mercury lamp. The lowest noise level of 3 x 10(-5) AU was obtained for the LED at 554 nm (determined at a detector time constant of 0.1 s). PMID:9034772

  13. Intensity of blue LED light: a potential stimulus for biomass and lipid content in fresh water microalgae Chlorella vulgaris.

    PubMed

    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. PMID:24063820

  14. Light Scattering by Coated Sphere Immersed in Absorbing Medium: A Comparison between the FDTD and Analytic Solutions

    NASA Technical Reports Server (NTRS)

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

    2004-01-01

    A recently developed finite-difference time domain scheme is examined using the exact analytic solutions for light scattering by a coated sphere immersed in an absorbing medium. The relative differences are less than 1% in the extinction, scattering, and absorption efficiencies and less than 5% in the scattering phase functions. The definition of apparent single-scattering properties is also discussed. (C) 2003 Elsevier Ltd. All rights reserved.

  15. Efficient white phosphorescent organic light-emitting diodes consisting of orange ultrathin and blue mixed host emission layers

    NASA Astrophysics Data System (ADS)

    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.

  16. High efficient white organic light-emitting diodes with single emissive layer using phosphorescent red, green, and blue dopants

    NASA Astrophysics Data System (ADS)

    Kim, You-Hyun; Wai Cheah, Kok; Young Kim, Woo

    2013-07-01

    Phosphorescent white organic light-emitting diodes (PHWOLEDs) with single emissive layer were fabricated by co-doping phosphorescent blue, green, and red emitters with different concentrations. WOLEDs using Ir(piq)3 and Ir(ppy)3 as red and green dopants along with 8% of Firpic as blue dopant with host materials of 4CzPBP in the emissive layer were compared under various doping ratio between Ir(piq)3 and Ir(ppy)3. Triplet-triplet Dexter energy transfer in single emissive PHWOLEDs including three primary colors was saturated from higher triplet energy levels to lower triplet energy levels directly.

  17. A chimeric light-regulated amino acid transport system allows the isolation of blue light regulator (blr) mutants of Neurospora crassa.

    PubMed Central

    Carattoli, A; Kato, E; Rodriguez-Franco, M; Stuart, W D; Macino, G

    1995-01-01

    We have developed a system for the isolation of Neurospora crassa mutants that shows altered responses to blue light. To this end we have used the light-regulated promoter of the albino-3 gene fused to the neutral amino acid permease gene mtr. The product of the mtr gene is required for the uptake of neutral aliphatic and aromatic amino acids, as well as toxic analogs such as p-flurophenylalanine or 4-methyltryptophan. mtr trp-2-carrying cells were transformed with the al-3 promoter-mtr wild-type gene (al-3p-mtr+) to obtain a strain with a light-regulated tryptophan uptake. This strain is sensitive to p-fluorophenylalanine when grown under illumination and resistant when grown in the dark. UV mutagenesis of the al-3p-mtr(+)-carrying strain allowed us to isolate two mutant strains, BLR-1 and BLR-2 (blue light regulator), that are light-resistant to p-fluorophenylalanine and have lost the ability to grow on tryptophan. These two strains have a pale-orange phenotype and show down-regulation of all the photoregulated genes tested (al-3, al-1, con-8, and con-10). Mutations in the BLR strains are not allelic with white collar 1 or white collar 2, regulatory genes that are also involved in the response to blue light. Images Fig. 2 Fig. 3 Fig. 4 PMID:7604041

  18. Optical properties of light absorbing carbon aggregates mixed with sulfate: assessment of different model geometries for climate forcing calculations.

    PubMed

    Kahnert, Michael; Nousiainen, Timo; Lindqvist, Hannakaisa; Ebert, Martin

    2012-04-23

    Light scattering by light absorbing carbon (LAC) aggregates encapsulated into sulfate shells is computed by use of the discrete dipole method. Computations are performed for a UV, visible, and IR wavelength, different particle sizes, and volume fractions. Reference computations are compared to three classes of simplified model particles that have been proposed for climate modeling purposes. Neither model matches the reference results sufficiently well. Remarkably, more realistic core-shell geometries fall behind homogeneous mixture models. An extended model based on a core-shell-shell geometry is proposed and tested. Good agreement is found for total optical cross sections and the asymmetry parameter. PMID:22535095

  19. Effect of Hole Mobility Through Emissive Layer on Temporal Stability of Blue Organic Light-Emitting Diodes

    SciTech Connect

    Culligan, S.W.; Chen, A.C.-A.; Wallace, J.U.; Klubek, K.P.; Tang, C.W.; Chen, S.H.

    2006-07-13

    Light-emitting conjugated oligomers comprising anthracene, naphthalene, and fluorene units have been synthesized to investigate three configurations of blue organic light-emitting diodes (OLEDs) that are designed to identify the origins of device instablilty. The transient OLED technique is employed to measure hole mobilities, which are found to be 3.1 x 10^-4, 8.9 x 10^-5, and 3.6 x 10^-5 cm^2V^-1s^-1 for three different blue-light-emitting model compounds with varying fluorene content. A higher hole mobility through the emissive layer results in a wider recombination zone, which, in turn, is responsible for a longer device lifetime and a lower drive voltage at the expense of luminance yield.

  20. Blue-light receptor in a white mutant of Physarum polycephalum mediates inhibition of spherulation and regulation of glucose metabolism.

    PubMed Central

    Schreckenbach, T; Walckhoff, B; Verfuerth, C

    1981-01-01

    Blue light induces sporulation of Physarum polycephalum macroplasmodia and reversibly inhibits spherulation (sclerotization) of microplasmodia. Illuminated microplasmodia have an abnormal appearance. The photobiological responses of the plasmodia appear to be unaffected by the absence of yellow pigment in the white mutant strain used. Illumination of microplasmodial suspensions with blue light (lambda max approximately 465 nm) results also in an early effect on glucose metabolism: glucose consumption is reversibly inhibited. By using radioactive glucose it was shown that the main products formed are a water-insoluble glucan and the disaccharide trehalose. Inhibition of glucose consumption in the light results in decreased production of these two compounds. Illumination of microplasmodial suspensions also causes a reversible effect on the pH of the medium which is interpreted as a decreased production of a yet unidentified acid from glucose. The action spectrum of the light-induced pH response shows maxima near 390, 465, and 485 nm. It resembles the absorption spectrum of a flavoprotein and confirms the existence of a blue-light receptor in P. polycephalum microplasmodia. Images PMID:6940119

  1. Photocatalytic degradation of methylene blue under UV light irradiation on prepared carbonaceous TiO2.

    PubMed

    Ramli, Zatil Amali Che; Asim, Nilofar; Isahak, Wan N R W; Emdadi, Zeynab; Ahmad-Ludin, Norasikin; Yarmo, M Ambar; Sopian, K

    2014-01-01

    This study involves the investigation of altering the photocatalytic activity of TiO2 using composite materials. Three different forms of modified TiO2, namely, TiO2/activated carbon (AC), TiO2/carbon (C), and TiO2/PANi, were compared. The TiO2/carbon composite was obtained by pyrolysis of TiO2/PANi prepared by in situ polymerization method, while the TiO2/activated carbon (TiO2/AC) was obtained after treating TiO2/carbon with 1.0 M KOH solution, followed by calcination at a temperature of 450°C. X-ray powder diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infrared (FTIR), thermogravimetric analysis (TG-DTA), Brunauer-Emmet-Teller (BET), and UV-Vis spectroscopy were used to characterize and evaluate the prepared samples. The specific surface area was determined to be in the following order: TiO2/AC > TiO2/C > TiO2/PANi > TiO2 (179 > 134 > 54 > 9 m(2) g(-1)). The evaluation of photocatalytic performance for the degradation of methylene blue under UV light irradiation was also of the same order, with 98 > 84.7 > 69% conversion rate, which is likely to be attributed to the porosity and synergistic effect in the prepared samples. PMID:25013855

  2. Photocatalytic Degradation of Methylene Blue under UV Light Irradiation on Prepared Carbonaceous TiO2

    PubMed Central

    Che Ramli, Zatil Amali; Asim, Nilofar; Isahak, Wan N. R. W.; Emdadi, Zeynab; Ahmad-Ludin, Norasikin; Yarmo, M. Ambar; Sopian, K.

    2014-01-01

    This study involves the investigation of altering the photocatalytic activity of TiO2 using composite materials. Three different forms of modified TiO2, namely, TiO2/activated carbon (AC), TiO2/carbon (C), and TiO2/PANi, were compared. The TiO2/carbon composite was obtained by pyrolysis of TiO2/PANi prepared by in situ polymerization method, while the TiO2/activated carbon (TiO2/AC) was obtained after treating TiO2/carbon with 1.0 M KOH solution, followed by calcination at a temperature of 450°C. X-ray powder diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infrared (FTIR), thermogravimetric analysis (TG-DTA), Brunauer-Emmet-Teller (BET), and UV-Vis spectroscopy were used to characterize and evaluate the prepared samples. The specific surface area was determined to be in the following order: TiO2/AC > TiO2/C > TiO2/PANi > TiO2 (179 > 134 > 54 > 9 m2 g−1). The evaluation of photocatalytic performance for the degradation of methylene blue under UV light irradiation was also of the same order, with 98 > 84.7 > 69% conversion rate, which is likely to be attributed to the porosity and synergistic effect in the prepared samples. PMID:25013855

  3. Cathodes incorporating thin fluoride layers for efficient injection in blue polymer light-emitting diodes

    NASA Astrophysics Data System (ADS)

    Brown, Thomas M.; Millard, Ian S.; Lacey, David; Burroughes, Jeremy H.; Friend, Richard H.; Cacialli, Franco

    2002-02-01

    Efficient blue Polymer Light-Emitting Diodes (PLEDs) were fabricated by evaporating thin LiF layers between Al or Ca cathodes. Electroabsorption measurements of the built-in potential across the diodes show that devices fabricated with LiF/Ca/Al cathodes exhibit the smallest average barrier height and operating voltage (compared to both Ca and LiF/Al currently amongst the most efficient electron injectors). The turn-on bias is essentially equivalent to the built-in potential (~2.7 V), indicating an effective minimisation of the barrier to electron injection. Results are also compared with devices incorporating CsF layers and are correlated with the electroluminescent characteristics of the LEDs. A very strong dependence (~ exponential) between the built-in potential and the current and luminance at a fixed electric field (0.5MV/cm) is observed and is explained with the reduction of the cathodic barrier height brought about by the different cathode multilayers.

  4. Mechanism of blue-light-induced plasma-membrane depolarization in etiolated cucumber hypocotyls

    NASA Technical Reports Server (NTRS)

    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.

  5. Plasma treated with methylene blue and light: clinical efficacy and safety profile.

    PubMed

    Lozano, Miguel; Cid, Joan; Müller, Thomas H

    2013-10-01

    Methylene blue (MB) was the first method developed for pathogen inactivation of a labile blood component that was introduced in 1991. MB and light (MBL) inactivates most lipid-enveloped viruses and those non-enveloped are, in general, resistant. MBL treatment affects several coagulation factors, most noticeably fibrinogen and factor VIII with a loss of approximately 30%. Using endogenous thrombin potential, a global hemostasis evaluation, MBL treatment of plasma resulted in a 7% to 10% of reduction in thrombin potential. Although, originally, the scientific evidence of its efficacy and safety were scarce, the 4.4 million of units transfused have provided a wide body of evidence of its efficacy and safety in most of clinical situations. Nevertheless, some doubts have arisen about the efficacy of MBL plasma when used as a replacement solution for plasma exchange in the treatment of patients suffering from TTP. Probably only randomized controlled trials would provide definite evidence to clarify this point. Reports of severe allergic reactions in a few patients receiving MBL plasma have provoked the recent decision to remove the product from the market in France. Interestingly hemovigilance data in countries such as the same France, Spain, and United Kingdom have not corroborated an increase in severe allergic reaction. Close monitoring of the patients receiving plasma and suffering from allergic reactions and reporting to hemovigilance schemes hopefully will provide the needed data to definitely establish the exact risk of this complication for MBL vs other types of plasma. PMID:24075476

  6. A sensitive resveratrol assay with a simple probe methylene blue by resonance light scattering technique

    NASA Astrophysics Data System (ADS)

    Xiang, Haiyan; Dai, Kaijin; Luo, Qizhi; Duan, Wenjun; Xie, Yang

    2011-01-01

    A novel resonance light scattering (RLS) method was developed for the determination of resveratrol based on the interaction between resveratrol and methylene blue (MB). It was found that at pH 8.69, the weak RLS intensity of MB was remarkably enhanced by the addition of trace amount of resveratrol with the maximum peak located at 385.0 nm. Under the optimum conditions, a good linear relationship between the enhanced RLS intensities and the concentrations of resveratrol was obtained over the range of 2.0-14.0 μg ml -1 with the detection limit (3 σ) of 0.63 μg ml -1. The results of the analysis of resveratrol in synthetic samples and human urine are satisfactory, which showed it may provide a more sensitive, convenient, rapid and reproducible method for the detection of resveratrol, especially in biological and pharmaceutical field. In this work, the characteristics of RLS, absorption and fluorescence spectra of the resveratrol-MB system, the influencing factors and the optimum conditions of the reaction were investigated.

  7. Photoinhibition of stem elongation by blue and red light. Effects on hydraulic and cell wall properties

    SciTech Connect

    Kigel, J.; Cosgrove, D.J. Pennsylvania State Univ., University Park )

    1991-04-01

    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 (lay 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 yield coefficient, while most of the inhibitory effect of BL was due to an increase of the yield threshold. Mechanical extensibility of cell walls (Instron technique) was decreased by BL and RL, mainly due to a reduction in the plastic component of extensibility. Thus, photoinhibitions of elongation by both BL and RL are achieved through changes in cell wall properties, and are not due to effects on the hydraulic properties of the cell.

  8. Photoinhibition of stem elongation by blue and red light: effects on hydraulic and cell wall properties

    NASA Technical Reports Server (NTRS)

    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 yield coefficient, while most of the inhibitory effect of BL was due to an increase of the yield threshold. Mechanical extensibility of cell walls (Instron technique) was decreased by BL and RL, mainly due to a reduction in the plastic component of extensibility. Thus, photoinhibitions of elongation by both BL and RL are achieved through changes in cell wall properties, and are not due to effects on the hydraulic properties of the cell.

  9. Civilian pilot exposure to ultraviolet and blue light and pilot use of sunglasses.

    PubMed

    Chorley, Adrian C; Evans, Bruce J W; Benwell, Martin J

    2011-09-01

    Population and animal studies indicate that long-term exposure to short-wavelength visible light and ultraviolet (UV) radiation causes increased risk of certain ocular pathologies such as cataracts and maculopathy. The potential risk to flight crew is unknown. The UK Civil Aviation Authority (CAA) has issued guidance to pilots regarding sunglass selection; however, it is not known if this guidance is appropriate given pilots' unique occupational environment. A search and appraisal of the relevant literature was conducted which showed that within the airline pilot population, there is limited evidence of a higher prevalence of cataracts. There are no data of other known UV-related ocular pathology. There is some evidence of higher prevalence of skin melanomas. Studies measuring cockpit UV radiation levels are limited and leave unanswered questions regarding airline pilot exposure. Data from optical transmission of cockpit windshields demonstrates the UV blocking properties at sea level. No studies have addressed the occupational use of sunglasses in airline pilots. Although it is likely that an aircraft windshield effectively blocks UV-B, the intensity of UV-A and short wavelength blue light present within the cockpit at altitude is unknown. Pilots may be exposed to solar radiation for periods of many hours during flight where UV radiation is known to be significantly greater. Aircraft windshields should have a standard for optical transmission, particularly of short-wavelength radiation. Clear, untinted prescription glasses will offer some degree of UV protection; however, sunglasses will offer superior protection. Any sunglasses used should conform to a national standard. PMID:21888274

  10. Low Power, Red, Green and Blue Carbon Nanotube Enabled Vertical Organic Light Emitting Transistors for Active Matrix OLED Displays

    SciTech Connect

    McCarthy, M. A.; Liu, B.; Donoghue, E. P.; Kravchenko, Ivan I; Kim, D. Y.; So, Franky; Rinzler, A. G.

    2011-01-01

    Organic semiconductors are potential alternatives to polycrystalline silicon as the semiconductor used in the backplane of active matrix organic light emitting diode displays. Demonstrated here is a light-emitting transistor with an organic channel, operating with low power dissipation at low voltage, and high aperture ratio, in three colors: red, green and blue. The single-wall carbon nanotube network source electrode is responsible for the high level of performance demonstrated. A major benefit enabled by this architecture is the integration of the drive transistor, storage capacitor and light emitter into a single device. Performance comparable to commercialized polycrystalline-silicon TFT driven OLEDs is demonstrated.

  11. The physical properties of black carbon and other light-absorbing material emitted from prescribed fires in the United States

    NASA Astrophysics Data System (ADS)

    McMeeking, G. R.; Kreidenweis, S. M.; Yokelson, R. J.; Sullivan, A. P.; Lee, T.; Collett, J. L.; Fortner, E.; Onasch, T. B.; Akagi, S. K.; Taylor, J.; Coe, H.

    2012-12-01

    Black carbon (BC) aerosol emitted from fires absorbs light, leading to visibility degradation as well as regional and global climate impacts. Fires also emit a wide range of trace gases and particulates that can interact with emitted BC and alter its optical properties and atmospheric lifetime. Non-BC particulate species emitted by fires can also scatter and absorb light, leading to additional effects on visibility. Recent work has shown that certain organic species can absorb light strongly at shorter wavelengths, giving it a brown or yellow color. This material has been classified as brown carbon, though it is not yet well defined. Land managers must find a balance between the negative impacts of prescribed fire emissions on visibility and air quality and the need to prevent future catastrophic wildfire as well as manage ecosystems for habitat restoration or other purposes. This decision process requires accurate assessments of the visibility impacts of fire emissions, including BC and brown carbon, which in turn depend on their optical properties. We present recent laboratory and aircraft measurements of black carbon and aerosol optical properties emitted from biomass burning. All measurement campaigns included a single particle soot photometer (SP2) instrument capable of providing size-resolved measurements of BC mass and number distributions and mixing state, which are needed to separate the BC and brown carbon contributions to total light absorption. The laboratory experiments also included a three-wavelength photoacoustic spectrometer that provided accurate measurements of aerosol light absorption. The laboratory systems also characterized emissions after they had been treated with a thermal denuder to remove semi-volatile coatings, allowing an assessment of the role of non-BC coatings on bulk aerosol optical properties. Emissions were also aged in an environmental smog chamber to examine the role of secondary aerosol production on aerosol optical properties.

  12. Blue- and green-absorbing visual pigments of Drosophila: ectopic expression and physiological characterization of the R8 photoreceptor cell-specific Rh5 and Rh6 rhodopsins.

    PubMed

    Salcedo, E; Huber, A; Henrich, S; Chadwell, L V; Chou, W H; Paulsen, R; Britt, S G

    1999-12-15

    Color discrimination requires the input of different photoreceptor cells that are sensitive to different wavelengths of light. The Drosophila visual system contains multiple classes of photoreceptor cells that differ in anatomical location, synaptic connections, and spectral sensitivity. The Rh5 and Rh6 opsins are expressed in nonoverlapping sets of R8 cells and are the only Drosophila visual pigments that remain uncharacterized. In this study, we ectopically expressed Rh5 and Rh6 in the major class of photoreceptor cells (R1-R6) and show them to be biologically active in their new environment. The expression of either Rh5 or Rh6 in "blind" ninaE(17) mutant flies, which lack the gene encoding the visual pigment of the R1-R6 cells, fully rescues the light response. Electrophysiological analysis showed that the maximal spectral sensitivity of the R1-R6 cells is shifted to 437 or 508 nm when Rh5 or Rh6, respectively, is expressed in these cells. These spectral sensitivities are in excellent agreement with intracellular recordings of the R8p and R8y cells measured in Calliphora and Musca. Spectrophotometric analyses of Rh5 and Rh6 in vivo by microspectrophotometry, and of detergent-extracted pigments in vitro, showed that Rh5 is reversibly photoconverted to a stable metarhodopsin (lambda(max) = 494 nm), whereas Rh6 appears to be photoconverted to a metarhodopsin (lambda(max) = 468 nm) that is less thermally stable. Phylogenetically, Rh5 belongs to a group of short-wavelength-absorbing invertebrate visual pigments, whereas Rh6 is related to a group of long-wavelength-absorbing pigments and is the first member of this class to be functionally characterized. PMID:10594055

  13. Photomorphogenesis, photosynthesis, and seed yield of wheat plants grown under red light-emitting diodes (LEDs) with and without supplemental blue lighting.

    PubMed

    Goins, G D; Yorio, N C; Sanwo, M M; Brown, C S

    1997-07-01

    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. PMID:11541074

  14. Red Light Combined with Blue Light Irradiation Regulates Proliferation and Apoptosis in Skin Keratinocytes in Combination with Low Concentrations of Curcumin.

    PubMed

    Niu, Tianhui; Tian, Yan; Cai, Qing; Ren, Qu; Wei, Lizhao

    2015-01-01

    Curcumin is a widely known natural phytochemical from plant Curcuma longa. In recent years, curcumin has received increasing attention because of its capability to induce apoptosis and inhibit cell proliferation as well as its anti-inflammatory properties in different cancer cells. However, the therapeutic benefits of curcumin are severely hampered due to its particularly low absorption via trans-dermal or oral bioavailability. Phototherapy with visible light is gaining more and more support in dermatological therapy. Red light is part of the visible light spectrum, which is able to deeply penetrate the skin to about 6 mm, and directly affect the fibroblast of the skin dermis. Blue light is UV-free irradiation which is fit for treating chronic inflammation diseases. In this study, we show that curcumin at low concentrations (1.25-3.12 μM) has a strong anti-proliferative effect on TNF-α-induced psoriasis-like inflammation when applied in combination with light-emitting-diode devices. The treatment was especially effective when LED blue light at 405 nm was combined with red light at 630 or 660 nm, which markedly amplified the anti-proliferative and apoptosis-inducing effects of curcumin. The experimental results demonstrated that this treatment reduced the viability of human skin keratinocytes, decreased cell proliferation, induced apoptosis, inhibited NF-κB activity and activated caspase-8 and caspase-9 while preserving the cell membrane integrity. Moreover, the combined treatment also down-regulated the phosphorylation level of Akt and ERK. Taken together, our results indicated that the combination of curcumin with LED blue light united red light irradiation can attain a higher efficiency of regulating proliferation and apoptosis in skin keratinocytes. PMID:26382065

  15. Role of the Alternaria alternata Blue-Light Receptor LreA (White-Collar 1) in Spore Formation and Secondary Metabolism

    PubMed Central

    Pruß, Sonja; Fetzner, Ramona; Seither, Kristin; Herr, Andreas; Pfeiffer, Erika; Metzler, Manfred; Lawrence, Christopher B.

    2014-01-01

    Alternaria alternata is a filamentous fungus that causes considerable loss of crops of economically important feed and food worldwide. It produces more than 60 different secondary metabolites, among which alternariol (AOH) and altertoxin (ATX) are the most important mycotoxins. We found that mycotoxin production and spore formation are regulated by light in opposite ways. Whereas spore formation was largely decreased under light conditions, the production of AOH was stimulated 2- to 3-fold. ATX production was even strictly dependent on light. All light effects observed could be triggered by blue light, whereas red light had only a minor effect. Inhibition of spore formation by light was reversible after 1 day of incubation in the dark. We identified orthologues of genes encoding the Neurospora crassa blue-light-perceiving white-collar proteins, a cryptochrome, a phytochrome, and an opsin-related protein in the genome of A. alternata. Deletion of the white-collar 1 (WC-1) gene (lreA) resulted in derepression of spore formation in dark and in light. ATX formation was strongly induced in the dark in the lreA mutant, suggesting a repressing function of LreA, which appears to be released in the wild type after blue-light exposure. In addition, light induction of AOH formation was partially dependent on LreA, suggesting also an activating function. A. alternata ΔlreA was still able to partially respond to blue light, indicating the action of another blue-light receptor system. PMID:24532063

  16. Characteristics of InGaN-Based UV/Blue/Green/Amber/Red Light-Emitting Diodes

    NASA Astrophysics Data System (ADS)

    Mukai, Takashi; Yamada, Motokazu; ShujiNakamura, ShujiNakamura

    1999-07-01

    Highly efficient light-emitting diodes (LEDs) emitting ultraviolet (UV), blue, green, amber and red light have been obtained through the use of InGaN active layers instead of GaN active layers. Red LEDs with an emission wavelength of 675 nm, whose emission energy was almost equal to the band-gap energy of InN, were fabricated. The dependence of the emission wavelength of the red LED on the current (blue shift) is dominated by both the band-filling effect of the localized energy states and the screening effect of the piezoelectric field. In the red LEDs, a phase separation of the InGaN layer was clearly observed in the emission spectra, in which blue and red emission peaks appeared. In terms of the temperature dependence of the LEDs, InGaN LEDs are superior to the conventional red and amber LEDs due to a large band offset between the active and cladding layers. The localized energy states caused by In composition fluctuation in the InGaN active layer contribute to the high efficiency of the InGaN-based emitting devices, in spite of the large number of threading dislocations and a large effect of the piezoelectric field. The blue and green InGaN-based LEDs had the highest external quantum efficiencies of 18% and 20% at low currents of 0.6 mA and 0.1 mA, respectively.

  17. Monolithic InGaN-based white light-emitting diodes with blue, green, and amber emissions

    NASA Astrophysics Data System (ADS)

    Lee, Sung-Nam; Paek, H. S.; Kim, H.; Jang, T.; Park, Y.

    2008-02-01

    We demonstrated a monolithic white light-emitting diodes (LEDs) epitaxial structure with blue, green, and amber emissions by introducing the blue InGaN /GaN five quantum wells (QWs) and InGaN /GaN single quantum well (SQW) with In-phase separated green/amber emissions as an active layer. Three wavelength emissions were developed by increasing the thickness of InGaN SQW grown on blue InGaN five QWs. From high resolution transmission electron microscope, In-phase separation was clearly observed in a 3.5-nm-thick InGaN SQW. In-phase separation would be generated by the spinodal decomposition which was promoted by the composition pulling effect related to the increment of well thickness. Therefore, white lighting LEDs with three wavelengths for blue emission from InGaN /GaN five QWs and green/amber emissions were achieved by the In-phase separation in InGaN SQW.

  18. Improved Light Extraction Efficiency in Blue Light-Emitting Diodes by SiO2-Coated ZnO Nanorod Arrays

    NASA Astrophysics Data System (ADS)

    Cho, Chu-Young; Kim, Na-Yeong; Kang, Jang-Won; Leem, Young-Chul; Hong, Sang-Hyun; Lim, Wantae; Kim, Sung-Tae; Park, Seong-Ju

    2013-04-01

    We report on the improved light extraction efficiency of blue light-emitting diodes (LEDs) by SiO2-coated ZnO nanorods (NRs) grown on indium-tin oxide (ITO). The optical output power of the LEDs with SiO2-coated ZnO NRs, which are grown on the patterned sapphire substrates, increases by 5% at 20 mA, compared with that of LEDs with bare ZnO NRs. This increase is attributed to the improved light extraction efficiency of LEDs because the SiO2 layer with a refractive index lower than that of ZnO NRs further reduces the Fresnel reflection.

  19. Secondary brown carbon - Formation of light-absorbing compounds in atmospheric particulates from selected dicarbonyls and amines

    NASA Astrophysics Data System (ADS)

    Kampf, Christopher; Filippi, Alexander; Hoffmann, Thorsten

    2015-04-01

    One of the main open questions regarding organic compounds in atmospheric chemistry today is related to the formation of optically-active compounds and the occurrence of so called brown carbon (Andreae and Gelencsér, 2006). While organic compounds in ambient fine particles for decades have been assumed to not absorb solar radiation, thus resulting in a net cooling effect on climate (IPCC, 2007), it is now generally accepted that a continuum of light-absorbing carbonaceous species is present in fine aerosols (Pöschl, 2003). In this study, light-absorbing compounds from reactions between dicarbonyl compounds, i.e., glyoxal, methylglyoxal, acetylacetone, 2,3-butanedione, 2,5-hexanedione, and glutaraldehyde, and amine species, i.e., ammonia and glycine, were investigated at atmospherically relevant concentrations in bulk solution experiments mimicking atmospheric particulates. Product analyses were performed using UV/Vis spectrophotometry and (ultra) high performance liquid chromatography coupled to diode array detection and ion trap mass spectrometry (HPLC-DAD-ESI-MS/MS), as well as ultra-high resolution (Orbitrap) mass spectrometry (UHPLC-ESI-HRMS/MS). We demonstrate that light-absorbing compounds are formed from a variety of atmospherically relevant dicarbonyls via particle phase reactions with amine nucleophiles. Single dicarbonyl and mixed dicarbonyl experiments were performed and products were analyzed. The reaction products are suggested to be cyclic nitrogen containing compounds such as imidazoles or dihydropyridines as well as open chain compounds resulting from aldol condensation reactions. Further, the reactive turnover was found to be higher at increasing pH values. The aforementioned processes may be of higher relevance in regions with high aerosol pH, e.g., resulting from high ammonia emissions as for example in northern India (Clarisse et al., 2009). References Andreae, M.O., and Gelencsér, A. (2006): Black carbon or brown carbon? The nature of light-absorbing

  20. Absorbance detector for capillary electrophoresis based on light-emitting diodes and photodiodes for the deep-ultraviolet range.

    PubMed

    Bui, Duy Anh; Hauser, Peter C

    2015-11-20

    A new absorbance detector for capillary electrophoresis featuring relatively high intensity light-emitting diodes as radiation sources and photodiodes for the deep-UV range was developed. The direct relationship of absorbance values and concentrations was obtained by emulating Lambert-Beer's law with the application of a beam splitter to obtain a reference signal and a log-ratio amplifier circuitry. The performance of the cell was investigated at 255 nm with the detection of sulfanilic, 4-nitrobenzoic, 4-hydroxybenzoic and 4-aminobenzoic acid and the indirect detection of acetate, propionate, butyrate and caproate using benzoate as the displacement dye molecule. Vanillic acid, L-tyrosine and DL-tryptophan as well as the sulfonamides sulfamerazine, sulfathiazole and sulfamethazine were determined at 280 nm. Good linearities over 3 orders of magnitude were obtained. The noise level recorded was as low as 50 μAU and the drift typically <200 μAU/5 min. PMID:26091783

  1. Effect of arylamine hole-transport units on the performance of blue polyspirobifulorene light-emitting diodes

    NASA Astrophysics Data System (ADS)

    Abbaszadeh, Davood; Nicolai, Herman T.; Crǎciun, N. Irina; Blom, Paul W. M.

    2014-11-01

    The operation of blue light-emitting diodes based on polyspirobifluorene with a varying number of N ,N ,N',N' tetraaryldiamino biphenyl (TAD) hole-transport units (HTUs) is investigated. Assuming that the electron transport is not affected by the incorporation of TAD units, model calculations predict that a concentration of 5% HTU leads to an optimal efficiency for this blue-emitting polymer. However, experimentally an optimum performance is achieved for 10% TAD HTUs. Analysis of the transport and recombination shows that polymer light-emitting diodes with 5%, 7.5%, and 12.5% TAD units follow the predicted behavior. The enhanced performance of the polymer with 10% TAD originates from a decrease in the number of electron traps, which is typically a factor of three lower than the universal value found in many polymers. This reduced number of traps leads to a reduction of nonradiative recombination and exciton quenching at the cathode.

  2. Polarization-multiplexed 2×2 phosphor-LED wireless light communication without using analog equalization and optical blue filter

    NASA Astrophysics Data System (ADS)

    Yeh, C. H.; Chen, H. Y.; Liu, Y. L.; Chow, C. W.

    2015-01-01

    We propose and experimentally demonstrate a 380 (2×190) Mbps phosphor-light-emitting-diode (LED) based visible light communication (VLC) system by using 2×2 polarization-multiplexing design for in-building access applications. To the best of our knowledge, this is the first time of employing polarization-multiplexing to achieve a high VLC transmission capacity by using phosphor-based white-LED without optical blue filter. Besides, utilizing the optimum resistor-inductor-capacity (RLC) bias-tee design, it can not only perform the function of combining the direct-current (DC) and the electrical data signal, but also act as a simple LED-Tx circuit. No optical blue filter and complicated post-equalization are required at the Rx. Here, the orthogonal-frequency-division-multiplexing (OFDM) quadrature-amplitude-modulation (QAM) with bit-loading is employed to enhance the transmission data rate.

  3. An ambipolar phosphine oxide-based host for high power efficiency blue phosphorescent organic light emitting devices

    SciTech Connect

    Polikarpov, Evgueni; Swensen, James S.; Chopra, Neetu; So, Franky; Padmaperuma, Asanga B.

    2009-06-01

    We report blue electrophosphorescent organic light emitting devices (OLEDs) with a new ambipolar host material, 4-(diphenylphosphoryl)-N,N-diphenylaniline (HM-A1), doped with the blue phosphor iridium (III) bis[(4,6-difluorophenyl)-pyridinato-N,C2’]picolinate (FIrpic). The ambipolar nature of the host was verified using single carrier devices. The power efficiency of devices that employed 2,8-bis(diphenylphosphoryl)dibenzothiophene (PO15) as the electron transport layer showed optimized device performance when the electron transport layer thickness was 500 Å, giving a peak power efficiency of 46 lm/W (corresponding external quantum efficiency of 17.1%). The external quantum efficiency and power efficiency at the brightness of 800 Cd/m2 were measured with no light outcoupling enhancement and found to be 15.4% and 26 lm/W, respectively.

  4. Cu2O nanoparticles decorated BiVO4 as an effective visible-light-driven p-n heterojunction photocatalyst for methylene blue degradation

    NASA Astrophysics Data System (ADS)

    Min, Shixiong; Wang, Fang; Jin, Zhiliang; Xu, Jing

    2014-10-01

    Bismuth vanadate (BiVO4) is a chemically stable and nontoxic semiconductor (SC) photocatalyst that can absorb visible light to degrade most of pollutants in aqueous solution due to suitable band-gap energy (ca. 2.4 eV), but it usually shows a low activity in its pristine form owing to poor charge-separation characteristics and the weak surface adsorption properties. In this paper, we demonstrated that the photocatalytic activity of BiVO4 can be greatly enhanced by surface modification with Cu2O nanoparticles through polyol reduction method. The modified photocatalysts (Cu2O/BiVO4) with proper loading amount of Cu2O (0.75 wt%) showed the highest photocatalytic degradation activity for methylene blue (MB) degradation with the pseudo-first-order rate constant kapp and degradation efficiency two times higher than pristine BiVO4 under visible light and solar light irradiation. The characterizations of resulting photocatalysts revealed that decoration of Cu2O nanoparticles led to the formation of a p-n heterojunction at the contact interface of Cu2O and BiVO4, which narrowed the band gap of BiVO4 for extending the absorption range of visible light and promoted the charge transfer across interface for suppressing the recombination of photogenerated electron-hole pairs, thus improving the catalytic performance of photocatalysts. This work demonstrates that the structural integration of p-type Cu2O SC with n-type BiVO4 SC will be a new promising strategy to develop a high-efficient heterojunction photocatalyst for visible-light-driven degradation of pollutants.

  5. Synthesis of fluorescent C2-bridged teraryls and quateraryls for blue, sky-blue, and green color light-emitting devices.

    PubMed

    Goel, Atul; Sharma, Ashutosh; Rawat, Madhu; Anand, R S; Kant, Ruchir

    2014-11-21

    A series of fluorescent teraryls and quateraryls were prepared from a ketene-S,S-acetal under mild conditions. These compounds exhibited blue, sky-blue and green color emissions both in the solid state and in a solution with good quantum yields, positive solvatochromic behavior, and reversible oxidation and reduction properties. The electronic characteristics of teraryl 6a and quateraryls 9a,b were examined by time-dependent density functional theory (TDDFT) calculations. Light-emitting devices were fabricated from teraryl 6a and quateraryls 9a,b as dyes and the configuration of ITO/PEDOT:PSS (40 nm)/NPB (20 nm)/ dye (50 nm)/BCP (7 nm)/ LiF (0.7 nm)/Al (200 nm), which exhibited electroluminescence maxima of 455, 480, and 525 nm, respectively. These devices operated at a substantially low turn-on voltage (3 and 4 V) and exhibited maximum luminance efficiencies of 0.62, 0.57, and 1.9 cd/A and brightnesses of 59, 160, and 1284 cd/m(2), respectively. PMID:25340860

  6. Early changes in gene expression induced by blue light irradiation of A2E-laden retinal pigment epithelial cells

    PubMed Central

    van der Burght, Barbro W.; Hansen, Morten; Olsen, Jørgen; Zhou, Jilin; Wu, Yalin; Nissen, Mogens H.; Sparrow, Janet R.

    2016-01-01

    Purpose Accumulation of bisretinoids as lipofuscin in retinal pigment epithelial (RPE) cells is implicated in the pathogenesis of some blinding diseases including age-related macular degeneration (AMD). To identify genes whose expression may change under conditions of bisretinoid accumulation, we 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 levels for the entire genome was determined using DNA microarrays (Affymetrix GeneChip Human Genome 2.0 Plus). Array results for selected genes were confirmed by real-time reverse-transcriptase polymerase chain reaction. Results Principal component analysis revealed that the A2E-laden RPE cells 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 that coded for proteins that have an inhibitory effect on the complement cascade: (complement factor H, complement factor H-related 1, complement factor I and vitronectin) and of two belonging to the classical pathway (complement component 1, s subcomponent and complement component 1, r subcomponent). 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 and can potentially serve as future therapeutic targets. PMID:23742627

  7. [The Nonlinear Effect of the Composite Influence of Red and Blue Light on Bacteria Escherichia coli Viability].

    PubMed

    Lukyanovich, P A; Zon, B A; Grabovich, M Yu; Shchelukhina, E V; Danilova, Yu I; Orlova, M V; Sapeltseva, Yu O; Sinugina, D I

    2016-01-01

    A non-linear dependence of the inhibition of E. coli cells is found when irradiated simultaneously with the blue and red regions of the spectrum at a power density of 100 mW/cm2. Such dependence is explained by the assumption of a cascade two-photon absorption of light by DNA molecules with an intermediate resonance at cellular chromophores, causing excitation and subsequent DNA damage similar to damage when exposed to UV radiation. PMID:27192833

  8. Mechanism of the down regulation of photosynthesis by blue light in the Cyanobacterium synechocystis sp. PCC 6803.

    PubMed

    Scott, Matt; McCollum, Chantal; Vasil'ev, Sergej; Crozier, Cheryl; Espie, George S; Krol, Marianna; Huner, Norm P A; Bruce, Doug

    2006-07-25

    Exposure to blue light has previously been shown to induce the reversible quenching of fluorescence in cyanobacteria, indicative of a photoprotective mechanism responsible for the down regulation of photosynthesis. We have investigated the molecular mechanism behind fluorescence quenching by characterizing changes in excitation energy transfer through the phycobilin pigments of the phycobilisome to chlorophyll with steady-state and time-resolved fluorescence excitation and emission spectroscopy. Quenching was investigated in both a photosystem II-less mutant, and DCMU-poisoned wild-type Synechocystis sp. PCC 6803. The action spectra for blue-light-induced quenching was identical in both cell types and was dominated by a band in the blue region, peaking at 480 nm. Fluorescence quenching and its dark recovery was inhibited by the protein cross-linking agent glutaraldehyde, which could maintain cells in either the quenched or the unquenched state. We found that high phosphate concentrations that inhibit phycobilisome mobility and the regulation of energy transfer by the light-state transition did not affect blue-light-induced fluorescence quenching. Both room temperature and 77 K fluorescence emission spectra revealed that fluorescence quenching was associated with phycobilin emission. Quenching was characterized by a decrease in the emission of allophycocyanin and long wavelength phycobilisome terminal emitters relative to that of phycocyanin. A global analysis of the room-temperature fluorescence decay kinetics revealed that phycocyanin and photosystem I decay components were unaffected by quenching, whereas the decay components originating from allophycocyanin and phycobilisome terminal emitters were altered. Our data support a regulatory mechanism involving a protein conformational change and/or change in protein-protein interaction which quenches excitation energy at the core of the phycobilisome. PMID:16846238

  9. Identification of a regulatory subunit of protein phosphatase 1 which mediates blue light signaling for stomatal opening.

    PubMed

    Takemiya, Atsushi; Yamauchi, Shota; Yano, Takayuki; Ariyoshi, Chie; Shimazaki, Ken-ichiro

    2013-01-01

    Protein phosphatase 1 (PP1) is a eukaryotic serine/threonine protein phosphatase comprised of a catalytic subunit (PP1c) and a regulatory subunit that modulates catalytic activity, subcellular localization and substrate specificity. PP1c positively regulates stomatal opening through blue light signaling between phototropins and the plasma membrane H(+)-ATPase in guard cells. However, the regulatory subunit functioning in this process is unknown. We identified Arabidopsis PRSL1 (PP1 regulatory subunit2-like protein1) as a regulatory subunit of PP1c. Tautomycin, a selective inhibitor of PP1c, inhibited blue light responses of stomata in the single mutants phot1 and phot2, supporting the idea that signals from phot1 and phot2 converge on PP1c. We obtained PRSL1 based on the sequence similarity to Vicia faba PRS2, a PP1c-binding protein isolated by a yeast two-hybrid screen. PRSL1 bound to Arabidopsis PP1c through its RVxF motif, a consensus PP1c-binding sequence. Arabidopsis prsl1 mutants were impaired in blue light-dependent stomatal opening, H(+) pumping and phosphorylation of the H(+)-ATPase, but showed normal phototropin activities. PRSL1 complemented the prsl1 phenotype, but not if the protein carried a mutation in the RVxF motif, suggesting that PRSL1 functions through binding PP1c via the RVxF motif. PRSL1 did not affect the catalytic activity of Arabidopsis PP1c but it stimulated the localization of PP1c in the cytoplasm. We conclude that PRSL1 functions as a regulatory subunit of PP1 and regulates blue light signaling in stomata. PMID:22585556

  10. Antimicrobial blue light inactivation of Candida albicans: In vitro and in vivo studies.

    PubMed

    Zhang, Yunsong; Zhu, Yingbo; Chen, Jia; Wang, Yucheng; Sherwood, Margaret E; Murray, Clinton K; Vrahas, Mark S; Hooper, David C; Hamblin, Michael R; Dai, Tianhong

    2016-07-01

    Fungal infections are a common cause of morbidity, mortality and cost in critical care populations. The increasing emergence of antimicrobial resistance necessitates the development of new therapeutic approaches for fungal infections. In the present study, we investigated the effectiveness of an innovative approach, antimicrobial blue light (aBL), for inactivation of Candida albicans in vitro and in infected mouse burns. A bioluminescent strain of C. albicans was used. The susceptibilities to aBL (415 nm) were compared between C. albicans and human keratinocytes. The potential development of aBL resistance by C. albicans was investigated via 10 serial passages of C. albicans on aBL exposure. For the animal study, a mouse model of thermal burn infected with the bioluminescent C. albicans strain was used. aBL was delivered to mouse burns approximately 12 h after fungal inoculation. Bioluminescence imaging was performed to monitor in real time the extent of infection in mice. The results obtained from the studies demonstrated that C. albicans was approximately 42-fold more susceptible to aBL than human keratinocytes. Serial passaging of C. albicans on aBL exposure implied a tendency of reduced aBL susceptibility of C. albicans with increasing numbers of passages; however, no statistically significant difference was observed in the post-aBL survival rate of C. albicans between the first and the last passage (P>0.05). A single exposure of 432 J/cm(2) aBL reduced the fungal burden in infected mouse burns by 1.75-log10 (P=0.015). Taken together, our findings suggest aBL is a potential therapeutic for C. albicans infections. PMID:26909654

  11. Changes on degree of conversion of dual-cure luting light-cured with blue LED

    NASA Astrophysics Data System (ADS)

    Bandéca, M. C.; El-Mowafy, O.; Saade, E. G.; Rastelli, A. N. S.; Bagnato, V. S.; Porto-Neto, S. T.

    2009-05-01

    The indirect adhesive procedures constitute recently a substantial portion of contemporary esthetic restorative treatments. The resin cements have been used to bond tooth substrate and restorative materials. Due to recently introduction of the self-bonding resin luting cement based on a new monomer, filler and initiation technology has become important to study the degree of conversion of these new materials. In the present work the polymerization reaction and the filler content of dual-cured dental resin cements were studied by means of infra-red spectroscopy (FT-IR) and thermogravimetry (TG). Twenty specimens were made in a metallic mold (8 mm diameter × 1 mm thick) from each of 2 cements, Panavia® F2.0 (Kuraray) and RelyX™ Unicem Applicap (3M/ESPE). Each specimen was cured with blue LED with power density of 500 mW/cm2 for 30 s. Immediately after curing, 24 and 48 h, and 7 days DC was determined. For each time interval 5 specimens were pulverized, pressed with KBr and analyzed with FT-IR. The TG measurements were performed in Netzsch TG 209 under oxygen atmosphere and heating rate of 10°C/min from 25 to 700°C. A two-way ANOVA showed DC (%) mean values statistically significance differences between two cements ( p < 0.05). The Tukey’s test showed no significant difference only for the 24 and 48 h after light irradiation for both resin cements ( p > 0.05). The Relx-Y™ Unicem mean values were significantly higher than Panavia® F 2.0. The degree of conversion means values increasing with the storage time and the filler content showed similar for both resin cements.

  12. Analysis of the effects of blue light on morphofunctional status of in vitro cultured blastocysts from mice carrying gene of enhanced green fluorescent protein (EGFP).

    PubMed

    Sakharova, N Yu; Mezhevikina, L M; Smirnov, A A; Vikhlyantseva, E F

    2014-05-01

    We studied the effect of blue light (440-490 nm) on the development of late blastocysts of mice carrying the gene of enhanced green fluorescent protein (EGFP). Exposure to blue light for 20 min reduced adhesive properties of blastocysts and their capacity to form primary colonies consisting of the cells of inner cell mass, trophoblast, and extraembryonic endoderm. The negative effects of blue light manifested in morphological changes in the primary colonies and impairment of differentiation and migration of cells of the trophoblast and extraembryonic endoderm. The problems of cell-cell interaction and inductive influences of the inner cell mass on other cell subpopulations are discussed. EGFP blastocysts were proposed as the model for evaluation of the mechanisms underlying the effects of blue light as the major negative factor of visible light used in in vitro experiments on mammalian embryos. PMID:24913583

  13. Leaf Morphology, Photosynthetic Performance, Chlorophyll Fluorescence, Stomatal Development of Lettuce (Lactuca sativa L.) Exposed to Different Ratios of Red Light to Blue Light

    PubMed Central

    Wang, Jun; Lu, Wei; Tong, Yuxin; Yang, Qichang

    2016-01-01

    Red and blue light are both vital factors for plant growth and development. We examined how different ratios of red light to blue light (R/B) provided by light-emitting diodes affected photosynthetic performance by investigating parameters related to photosynthesis, including leaf morphology, photosynthetic rate, chlorophyll fluorescence, stomatal development, light response curve, and nitrogen content. In this study, lettuce plants (Lactuca sativa L.) were exposed to 200 μmol⋅m−2⋅s−1 irradiance for a 16 h⋅d−1 photoperiod under the following six treatments: monochromatic red light (R), monochromatic blue light (B) and the mixture of R and B with different R/B ratios of 12, 8, 4, and 1. Leaf photosynthetic capacity (Amax) and photosynthetic rate (Pn) increased with decreasing R/B ratio until 1, associated with increased stomatal conductance, along with significant increase in stomatal density and slight decrease in stomatal size. Pn and Amax under B treatment had 7.6 and 11.8% reduction in comparison with those under R/B = 1 treatment, respectively. The effective quantum yield of PSII and the efficiency of excitation captured by open PSII center were also significantly lower under B treatment than those under the other treatments. However, shoot dry weight increased with increasing R/B ratio with the greatest value under R/B = 12 treatment. The increase of shoot dry weight was mainly caused by increasing leaf area and leaf number, but no significant difference was observed between R and R/B = 12 treatments. Based on the above results, we conclude that quantitative B could promote photosynthetic performance or growth by stimulating morphological and physiological responses, yet there was no positive correlation between Pn and shoot dry weight accumulation. PMID:27014285

  14. Leaf Morphology, Photosynthetic Performance, Chlorophyll Fluorescence, Stomatal Development of Lettuce (Lactuca sativa L.) Exposed to Different Ratios of Red Light to Blue Light.

    PubMed

    Wang, Jun; Lu, Wei; Tong, Yuxin; Yang, Qichang

    2016-01-01

    Red and blue light are both vital factors for plant growth and development. We examined how different ratios of red light to blue light (R/B) provided by light-emitting diodes affected photosynthetic performance by investigating parameters related to photosynthesis, including leaf morphology, photosynthetic rate, chlorophyll fluorescence, stomatal development, light response curve, and nitrogen content. In this study, lettuce plants (Lactuca sativa L.) were exposed to 200 μmol⋅m(-2)⋅s(-1) irradiance for a 16 h⋅d(-1) photoperiod under the following six treatments: monochromatic red light (R), monochromatic blue light (B) and the mixture of R and B with different R/B ratios of 12, 8, 4, and 1. Leaf photosynthetic capacity (A max) and photosynthetic rate (P n) increased with decreasing R/B ratio until 1, associated with increased stomatal conductance, along with significant increase in stomatal density and slight decrease in stomatal size. P n and A max under B treatment had 7.6 and 11.8% reduction in comparison with those under R/B = 1 treatment, respectively. The effective quantum yield of PSII and the efficiency of excitation captured by open PSII center were also significantly lower under B treatment than those under the other treatments. However, shoot dry weight increased with increasing R/B ratio with the greatest value under R/B = 12 treatment. The increase of shoot dry weight was mainly caused by increasing leaf area and leaf number, but no significant difference was observed between R and R/B = 12 treatments. Based on the above results, we conclude that quantitative B could promote photosynthetic performance or growth by stimulating morphological and physiological responses, yet there was no positive correlation between P n and shoot dry weight accumulation. PMID:27014285

  15. Predawn and high intensity application of supplemental blue light decreases the quantum yield of PSII and enhances the amount of phenolic acids, flavonoids, and pigments in Lactuca sativa

    PubMed Central

    Ouzounis, Theoharis; Razi Parjikolaei, Behnaz; Fretté, Xavier; Rosenqvist, Eva; Ottosen, Carl-Otto

    2015-01-01

    To evaluate the effect of blue light intensity and timing, two cultivars of lettuce [Lactuca sativa cv. “Batavia” (green) and cv. “Lollo Rossa” (red)] were grown in a greenhouse compartment in late winter under natural light and supplemental high pressure sodium (SON-T) lamps yielding 90 (±10) μmol m−2 s−1 for up to 20 h, but never between 17:00 and 21:00. The temperature in the greenhouse compartments was 22/11°C day/night, respectively. The five light-emitting diode (LED) light treatments were Control (no blue addition), 1B 06-08 (Blue light at 45 μmol m−2 s−1 from 06:00 to 08:00), 1B 21-08 (Blue light at 45 μmol m−2 s−1 from 21:00 to 08:00), 2B 17-19 (Blue at 80 μmol m−2 s−1 from 17:00 to 19:00), and 1B 17-19 (Blue at 45 μmol m−2 s−1 from 17:00 to 19:00). Total fresh and dry weight was not affected with additional blue light; however, plants treated with additional blue light were more compact. The stomatal conductance in the green lettuce cultivar was higher for all treatments with blue light compared to the Control. Photosynthetic yields measured with chlorophyll fluorescence showed different response between the cultivars; in red lettuce, the quantum yield of PSII decreased and the yield of non-photochemical quenching increased with increasing blue light, whereas in green lettuce no difference was observed. Quantification of secondary metabolites showed that all four treatments with additional blue light had higher amount of pigments, phenolic acids, and flavonoids compared to the Control. The effect was more prominent in red lettuce, highlighting that the results vary among treatments and compounds. Our results indicate that not only high light level triggers photoprotective heat dissipation in the plant, but also the specific spectral composition of the light itself at low intensities. However, these plant responses to light are cultivar dependent. PMID:25767473

  16. Nanostructured semiconductor solar absorbers with near 100% absorption and related light management picture

    NASA Astrophysics Data System (ADS)

    Li, Yali; Gao, Pingqi; Chen, Qiang; Yang, Jiaming; Li, Junshuai; He, Deyan

    2016-06-01

    Optical behaviors of both polycrystalline silicon (Si) and gallium arsenide (GaAs) nanocone (NC)-capped nanowire (NW) arrays are systematically investigated and a full light management picture is presented. The study demonstrates that compared to shape- and environment-sensitive optical resonance modes, including leaky modes and guided longitudinal resonances, optimization of light harvesting based on light scattering is more operable to guide related device fabrication. Under this consideration, near 100% absorption above the bandgap energy is realized for GaAs NC-capped NW arrays with an effective thickness of only ~1000 nm through balancing antireflection and light scattering in the optical systems. Further study under oblique incidence shows that light absorption for the optimized NC-capped NW arrays is almost insensitive to the incident angle, indicating excellent omnidirectional light management in the NC-capped NW configuration.

  17. Polarization-matched quaternary superlattice electron blocking layer in blue InGaN light-emitting diodes

    NASA Astrophysics Data System (ADS)

    Kuo, Yen-Kuang; Chen, Fang-Ming; Chang, Jih-Yuan; Lin, Bing-Cheng

    2016-05-01

    The effect of polarization-matched AlInGaN/AlGaN superlattice (SL) electron blocking layer (EBL) on the physical characteristics of blue InGaN light-emitting diodes (LEDs) is investigated numerically. Simulation results show that the optical performance of the LEDs with polarization-matched SL EBL can be markedly improved due to the effectively suppressed polarization effect, enhanced hole injection efficiency, and reduced electron overflow. Comparing to the LEDs with conventional AlGaN EBL, an improvement of 53% in light output power is achieved for the proposed LED structure.

  18. Phototropins But Not Cryptochromes Mediate the Blue Light-Specific Promotion of Stomatal Conductance, While Both Enhance Photosynthesis and Transpiration under Full Sunlight12[C][W][OA

    PubMed Central

    Boccalandro, Hernán E.; Giordano, Carla V.; Ploschuk, Edmundo L.; Piccoli, Patricia N.; Bottini, Rubén; Casal, Jorge J.

    2012-01-01

    Leaf epidermal peels of Arabidopsis (Arabidopsis thaliana) mutants lacking either phototropins 1 and 2 (phot1 and phot2) or cryptochromes 1 and 2 (cry1 and cry2) exposed to a background of red light show severely impaired stomatal opening responses to blue light. Since phot and cry are UV-A/blue light photoreceptors, they may be involved in the perception of the blue light-specific signal that induces the aperture of the stomatal pores. In leaf epidermal peels, the blue light-specific effect saturates at low irradiances; therefore, it is considered to operate mainly under the low irradiance of dawn, dusk, or deep canopies. Conversely, we show that both phot1 phot2 and cry1 cry2 have reduced stomatal conductance, transpiration, and photosynthesis, particularly under the high irradiance of full sunlight at midday. These mutants show compromised responses of stomatal conductance to irradiance. However, the effects of phot and cry on photosynthesis were largely nonstomatic. While the stomatal conductance phenotype of phot1 phot2 was blue light specific, cry1 cry2 showed reduced stomatal conductance not only in response to blue light, but also in response to red light. The levels of abscisic acid were elevated in cry1 cry2. We conclude that considering their effects at high irradiances cry and phot are critical for the control of transpiration and photosynthesis rates in the field. The effects of cry on stomatal conductance are largely indirect and involve the control of abscisic acid levels. PMID:22147516

  19. Effect of blue light emitting diodes on melanoma cells: involvement of apoptotic signaling.

    PubMed

    Oh, Phil-Sun; Na, Kyung Suk; Hwang, Hyosook; Jeong, Hwan-Seok; Lim, SeokTae; Sohn, Myung-Hee; Jeong, Hwan-Jeong

    2015-01-01

    The present study was undertaken to examine whether blue LED irradiation induces cellular apoptosis in B16-F10 cells and whether it blocks the early growth of melanoma cells in mice. Irradiation with blue LED was observed to reduce cell viability and to induce apoptotic cell death, as accompanied by exposure of phosphatidylserine on the plasma outside membrane and an accumulation of a sub-G1 population. Furthermore, the mitochondrial membrane potential increased, and mitochondria-related apoptotic proteins (cytochrome c, caspase 3, and PARP) were observed. In addition, the level of intracellular superoxide anion (O2(-)) gradually increased. Interestingly the phosphorylation of p53 increased at earlier times under blue LED irradiation, but reduced after exposure for a longer time. Additionally, the thickness of the mice footpad injected with B16-F10 cells decreased significantly until the 9th day of blue LED irradiation, indicating the inhibition of the early growth rate of the melanoma cells. Our data demonstrate that blue LED irradiation induces apoptotic cell death by activating the mitochondria-mediated pathway and reduces the early growth rate of melanoma cells. Further studies are needed to elucidate the precise mechanism of blue LED in melanoma cells. PMID:25550119

  20. Photo morphogenesis and photo response of the blue-light receptor gene Cmwc-1 in different strains of Cordyceps militaris.

    PubMed

    Yang, Tao; Dong, Caihong

    2014-03-01

    Light is a necessary environmental factor for stroma formation and development of Cordyceps militaris, a well-known edible and medicinal fungus. In this study, photo morphogenesis and the blue-light receptor gene were studied using five representative strains of C. militaris. The results suggest that light was essential for colony pigmentation and could promote conidia production. Cmwc-1, the homologe of the blue-light photoreceptor of Neurospora crassa, was cloned from the genome of C. militaris by Hi-tail PCR. The protein CmWC-1 was characterized by the presence of the LOV and PAS domains and a GATA-type Znf domain. Genetic variation analysis of Cmwc-1 in different strains showed that 15-bp deletions occurred in three strains that resulted in 5-Gln deletions in the transcription activation domain. Phylogenetic analysis based on the Sordariomycetes WC-1-like proteins suggested that the sequence of WC-1 could be used as a candidate marker for phylogenetic analysis in fungi. Cmwc-1 mRNA was light inducible and the expression level increased significantly after irradiation in all tested strains. The sequence of CmWC-1 and the relative expressions responding to irradiation in degenerate and albino strains were similar as the cultivated one. This report will help to open the still-unexplored field of stroma development for this fungus. PMID:24484244

  1. All solution processed blue multi-layer light emitting diodes realized by thermal layer stabilization and orthogonal solvent processing

    NASA Astrophysics Data System (ADS)

    Nau, Sebastian; Trattnig, Roman; Pevzner, Leonid; Jäger, Monika; Schlesinger, Raphael; Nardi, Marco V.; Ligorio, Giovanni; Christodoulou, Christos; Schulte, Niels; Winkler, Stefanie; Frisch, Johannes; Vollmer, Antje; Baumgarten, Martin; Sax, Stefan; Koch, Norbert; Müllen, Klaus; List-Kratochvil, Emil J. W.

    2013-09-01

    Herein we report on the fabrication and the properties of two highly efficient blue light emitting multilayer polymer light emitting diodes (PLEDs). The first device structure combines a thermally stabilized polymer with a material processed from an orthogonal solvent, allowing for the fabrication of a triple layer structure from solution. The well known poly(9,9-dioctyl-fluorene-co-N-(4-butylphenyl)-diphenylamine) (TFB), which can be stabilized in a bake-out procedure, was used as a hole transporting layer. A novel pyrene - triphenylamine (PPyrTPA) copolymer was used as emissive layer. The stack was finalized by a poly(fluorene) - derivative with polar side-chains, therefore being soluble in a polar solvent which allows for the deposition onto PPyrTPA without redissolving. The resulting PLED showed bright-blue electroluminescence (CIE1931 coordinates x=0.163; y=0.216) with a high efficiency of 1.42 cd/A and a peak luminescence of 16500 cd/m². The second presented device configuration comprises a thermally stabilized indenofluorene - triphenylamine copolymer acting as hole transporter, and an emissive copolymer with building blocks specifically designed for blue light emission, effective charge carrier injection and transport as well as for exciton generation. This multilayer PLED led to deep-blue emission (CIE1931 x=0.144; y=0.129) with a remarkably high device efficiency of 9.7 cd/A. Additionally, atomic force microscopy was carried out to investigate the film morphology of the components of the stack and x-ray photoemission spectroscopy was performed to ensure a full coverage of the materials on top of each other. Ultraviolet photoemission spectroscopy confirmed the desired type-II band level offsets on the individual interfaces.

  2. A comparative study of blue, green and yellow light emitting diode structures grown by metal organic chemical vapor deposition

    NASA Astrophysics Data System (ADS)

    Ramaiah, Kodigala Subba; Su, Y. K.; Chang, S. J.; Chen, C. H.

    2006-02-01

    The blue, green and yellow light emitting diode (LED) structures have been fabricated by metal organic chemical vapor deposition (MOCVD), and characterized by using different techniques, in order to understand the mechanism between these LEDs. Atomic force microscopy (AFM) analysis revealed that the surface roughness value and density of etch pits were different in the blue, green and yellow LEDs. The threading, misfit dislocations, interfacial dislocations, nano-pipe-like structures and quantum dot-like structures, which determine quality of the structures, were observed by transmission electron microscope (TEM) in the LED structures. The reasons for their formation in the layers are now elucidated. The indium composition, period width such as well and barrier widths were determined by simulating experimental high resolution X-ray diffraction (HRXRD) spectra. The In composition obtained by HRXRD and photoluminescence (PL) measurements for the same LED structure was not one and the same due to several reasons. In fact, the InGaN quantum well emission peaks at 2.667 and 2.544 eV of the blue and green LEDs, respectively showed S-shaped character shift, whereas the quantum well peak at 2.219 eV of yellow LEDs did not show any shift in the PL spectra with decreasing temperature. The blue, green and yellow LEDs showed different activation energies.

  3. Comparison of light out-coupling enhancements in single-layer blue-phosphorescent organic light emitting diodes using small-molecule or polymer hosts

    SciTech Connect

    Chang, Yung-Ting; Liu, Shun-Wei; Yuan, Chih-Hsien; Lee, Chih-Chien; Ho, Yu-Hsuan; Wei, Pei-Kuen; Chen, Kuan-Yu; Lee, Yi-Ting; Wu, Min-Fei; Chen, Chin-Ti E-mail: chihiwu@cc.ee.ntu.edu.tw; Wu, Chih-I E-mail: chihiwu@cc.ee.ntu.edu.tw

    2013-11-07

    Single-layer blue phosphorescence organic light emitting diodes (OLEDs) with either small-molecule or polymer hosts are fabricated using solution process and the performances of devices with different hosts are investigated. The small-molecule device exhibits luminous efficiency of 14.7 cd/A and maximum power efficiency of 8.39 lm/W, which is the highest among blue phosphorescence OLEDs with single-layer solution process and small molecular hosts. Using the same solution process for all devices, comparison of light out-coupling enhancement, with brightness enhancement film (BEF), between small-molecule and polymer based OLEDs is realized. Due to different dipole orientation and anisotropic refractive index, polymer-based OLEDs would trap less light than small molecule-based OLEDs internally, about 37% better based simulation results. In spite of better electrical and spectroscopic characteristics, including ambipolar characteristics, higher carrier mobility, higher photoluminescence quantum yield, and larger triplet state energy, the overall light out-coupling efficiency of small molecule-based devices is worse than that of polymer-based devices without BEF. However, with BEF for light out-coupling enhancement, the improved ratio in luminous flux and luminous efficiency for small molecule based device is 1.64 and 1.57, respectively, which are significantly better than those of PVK (poly-9-vinylcarbazole) devices. In addition to the theoretical optical simulation, the experimental data also confirm the origins of differential light-outcoupling enhancement. The maximum luminous efficiency and power efficiency are enhanced from 14.7 cd/A and 8.39 lm/W to 23 cd/A and 13.2 lm/W, respectively, with laminated BEF, which are both the highest so far for single-layer solution-process blue phosphorescence OLEDs with small molecule hosts.

  4. 'Self-absorbed' GeV light curves of gamma-ray burst afterglows

    SciTech Connect

    Panaitescu, A.; Vestrand, W. T.; Woźniak, P.

    2014-06-10

    We investigate the effect that the absorption of high-energy (above 100 MeV) photons produced in gamma-ray burst afterglow shocks has on the light curves and spectra of Fermi Large Area Telescope (LAT) afterglows. Afterglows produced by the interaction of a relativistic outflow with a wind-like medium peak when the blast wave deceleration sets in, and the afterglow spectrum could be hardening before that peak, as the optical thickness to pair formation is decreasing. In contrast, in afterglows produced in the interaction with a homogeneous medium, the optical thickness to pair formation should increase and yield a light curve peak when it reaches unity, followed by a fast light curve decay, accompanied by spectral softening. If energy is injected in the blast wave, then the accelerated increase of the optical thickness yields a convex afterglow light curve. Other features, such as a double-peak light curve or a broad hump, can arise from the evolution of the optical thickness to photon-photon absorption. Fast decays and convex light curves are seen in a few LAT afterglows, but the expected spectral softening is rarely seen in (and difficult to measure with) LAT observations. Furthermore, for the effects of photon-photon attenuation to shape the high-energy afterglow light curve without attenuating it too much, the ejecta initial Lorentz factor must be in a relatively narrow range (50-200), which reduces the chance of observing those effects.

  5. Phenolic carbonyls undergo rapid aqueous photodegradation to form low-volatility, light-absorbing products

    NASA Astrophysics Data System (ADS)

    Smith, Jeremy D.; Kinney, Haley; Anastasio, Cort

    2016-02-01

    We investigated the aqueous photochemistry of six phenolic carbonyls - vanillin, acetovanillone, guaiacyl acetone, syringaldehyde, acetosyringone, and coniferyl aldehyde - that are emitted from wood combustion. The phenolic carbonyls absorb significant amounts of solar radiation and decay rapidly via direct photodegradation, with lifetimes (τ) of 13-140 min under Davis, CA winter solstice sunlight at midday (solar zenith angle = 62°). The one exception is guaiacyl acetone, where the carbonyl group is not directly connected to the aromatic ring: This species absorbs very little sunlight and undergoes direct photodegradation very slowly (τ > 103 min). We also found that the triplet excited states (3C*) of the phenolic carbonyls rapidly oxidize syringol (a methoxyphenol without a carbonyl group), on timescales of 1-5 h for solutions containing 5 μM phenolic carbonyl. The direct photodegradation of the phenolic carbonyls, and the oxidation of syringol by 3C*, both efficiently produce low volatility products, with SOA mass yields ranging from 80 to 140%. Contrary to most aliphatic carbonyls, under typical fog conditions we find that the primary sink for the aromatic phenolic carbonyls is direct photodegradation in the aqueous phase. In areas of significant wood combustion, phenolic carbonyls appear to be small but significant sources of aqueous SOA: over the course of a few hours, nearly all of the phenolic carbonyls will be converted to SOA via direct photodegradation, enhancing the POA mass from wood combustion by approximately 3-5%.

  6. A novel bio-degradable polymer stabilized Ag/TiO2 nanocomposites and their catalytic activity on reduction of methylene blue under natural sun light.

    PubMed

    Geetha, D; Kavitha, S; Ramesh, P S

    2015-11-01

    In the present work we defined a novel method of TiO2 doped silver nanocomposite synthesis and stabilization using bio-degradable polymers viz., chitosan (Cts) and polyethylene glycol (PEG). These polymers are used as reducing agents. The instant formation of AgNPs was analyzed by visual observation and UV-visible spectrophotometer. TiO2 nanoparticles doped at different concentrations viz., 0.03, 0.06 and 0.09mM on PEG/Cts stabilized silver (0.04wt%) were successfully synthesized. This study presents a simple route for the in situ synthesis of both metal and polymer confined within the nanomaterial, producing ternary hybrid inorganic-organic nanomaterials. The results reveal that they have higher photocatalytic efficiencies under natural sun light. The synthesized TiO2 doped Ag nanocomposites (NCs) were characterized by SEM/EDS, TEM, XRD, FTIR and DLS with zeta potential. The stability of Ag/TiO2 nanocomposite is due to the high negative values of zeta potential and capping of constituents present in the biodegradable polymer which is evident from zeta potential and FT-IR studies. The XRD and EDS pattern of synthesized Ag/TiO2 NCs showed their crystalline structure, with face centered cubic geometry oriented in (111) plane. AFM and DLS studies revealed that the diameter of stable Ag/TiO2 NCs was approximately 35nm. Moreover the catalytic activity of synthesize Ag/TiO2 NCs in the reduction of methylene blue was studied by UV-visible spectrophotometer. The synthesized Ag/TiO2 NCs are observed to have a good catalytic activity on the reduction of methylene blue by bio-degradable which is confirmed by the decrease in absorbance maximum value of methylene blue with respect to time using UV-vis spectrophotometer. The significant enhancement in the photocatalytic activity of Ag/TiO2 nanocomposites under sun light irradiation can be ascribed to the effect of noble metal Ag by acting as electron traps in TiO2 band gap. PMID:25976106

  7. Peculiarities of propagation of quasi-diffraction-free light beams in strongly scattering absorbing media

    SciTech Connect

    Katsev, I L; Prikhach, A S; Kazak, N S; Kroening, M

    2006-04-30

    Based on the relation between the theory of light field coherence and theory of radiation transfer in scattering media, a method is proposed for calculating the illumination distribution produced by coherent quasi-diffraction-free beams at different penetration depths of radiation into scattering media such as biological tissues. The method uses the optical transfer function or the point spread function (PSF) of the medium. A simple and convenient analytic PSF model is described. Examples of the illumination distribution produced by a Bessel light beam in a medium with optical parameters typical of real biological tissues are presented. It is shown that the half-width of the axial maximum of a Bessel light beam scattered due to scattering almost does not increase up to optical depths where the contribution of multiple scattering is already considerable. (light beams)

  8. Formation of light absorbing organo-nitrogen species from evaporation of droplets containing glyoxal and ammonium sulfate

    NASA Astrophysics Data System (ADS)

    Lee, A.; Zhao, R.; Richard, L.; Liggio, G.; Li, S.; Abbatt, J.

    2013-12-01

    Formation of particle-phase organo-nitrogen compounds has been recently proposed via aqueous chemistry of glyoxal and ammonium sulfate in both dark and illuminated conditions. In the atmosphere, glyoxal can partition into aqueous droplets containing significant levels of different inorganic salts but their molecular interactions are still not well understood. Upon droplet evaporation, both the organics and inorganic ions become highly concentrated, accelerating reactions between them. To demonstrate this process, we investigated the formation of organo-nitrogen and light absorbing materials in evaporating droplets containing glyoxal and different ammonium salts including ammonium sulfate, ammonium nitrate and ammonium chloride. Our results demonstrate that evaporating glyoxal-ammonium sulfate droplets produce light absorbing species on a time scale of seconds, which is orders of magnitude faster than observed in bulk solutions. Using aerosol mass spectrometry, we show that particle-phase organics with high N:C ratios were formed when ammonium salts were used, and that the presence of sulfate ions promoted this chemistry. Since sulfate can also significantly enhance the Henry's law partitioning of glyoxal, our results highlight the atmospheric importance of such inorganic-organic interactions in aqueous phase aerosol chemistry.

  9. A Blue Light Inducible Two-Component Signal Transduction System in the Plant Pathogen Pseudomonas syringae pv. tomato☆

    PubMed Central

    Cao, Z.; Buttani, V.; Losi, A.; Gärtner, W.

    2008-01-01

    Abstract The open reading frame PSPTO2896 from the plant pathogen Pseudomonas syringae pv. tomato encodes a protein of 534 amino acids showing all salient features of a blue light-driven two-component system. The N-terminal LOV (light, oxygen, voltage) domain, potentially binding a flavin chromophore, is followed by a histidine kinase (HK) motif and a response regulator (RR). The full-length protein (PST-LOV) and, separately, the RR and the LOV+HK part (PST-LOVΔRR) were heterologously expressed and functionally characterized. The two LOV proteins showed typical LOV-like spectra and photochemical reactions, with the blue light-driven, reversible formation of a covalent flavin-cysteine bond. The fluorescence changes in the lit state of full-length PST-LOV, but not in PST-LOVΔRR, indicating a direct interaction between the LOV core and the RR module. Experiments performed with radioactive ATP uncover the light-driven kinase activity. For both PST-LOV and PST-LOVΔRR, much more radioactivity is incorporated when the protein is in the lit state. Furthermore, addition of the RR domain to the fully phosphorylated PST-LOVΔRR leads to a very fast transfer of radioactivity, indicating a highly efficient HK activity and a tight interaction between PST-LOVΔRR and RR, possibly facilitated by the LOV core itself. PMID:17905842

  10. LIGHT BEAMS: Peculiarities of propagation of quasi-diffraction-free light beams in strongly scattering absorbing media

    NASA Astrophysics Data System (ADS)

    Katsev, I. L.; Prikhach, A. S.; Kazak, N. S.; Kroening, M.

    2006-04-01

    Based on the relation between the theory of light field coherence and theory of radiation transfer in scattering media, a method is proposed for calculating the illumination distribution produced by coherent quasi-diffraction-free beams at different penetration depths of radiation into scattering media such as biological tissues. The method uses the optical transfer function or the point spread function (PSF) of the medium. A simple and convenient analytic PSF model is described. Examples of the illumination distribution produced by a Bessel light beam in a medium with optical parameters typical of real biological tissues are presented. It is shown that the half-width of the axial maximum of a Bessel light beam scattered due to scattering almost does not increase up to optical depths where the contribution of multiple scattering is already considerable.

  11. Primary photophysics of the FMN binding LOV2 domain of the plant blue light receptor phototropin of Avena sativa

    NASA Astrophysics Data System (ADS)

    Schüttrigkeit, Tanja A.; Kompa, Christian K.; Salomon, Michael; Rüdiger, Wolfhart; Michel-Beyerle, Maria E.

    2003-11-01

    The temporal evolution of the initially excited singlet state of flavine mononucleotide, which is the cofactor in the LOV2 domain of the blue photoreceptor phototropin, has been studied in picosecond time-resolved fluorescence and femtosecond time-resolved absorption experiments. In the LOV2-WT protein of Avena sativa singlet-triplet intersystem crossing proceeding within 2.3 ns is the primary process which increases the triplet yield by a factor of 1.23 as compared to a mutant where cysteine 39 is replaced by alanine. This flavin triplet state is responsible for the formation of a cysteinyl-flavin adduct which triggers the unique photocycle of the LOV2 domain and thus the sensoric function of the blue light receptor phototropin.

  12. High-efficiency blue multilayer polymer light-emitting diode based on poly(9,9-dioctylfluorene)

    NASA Astrophysics Data System (ADS)

    Tseng, Shin-Rong; Li, Shiuan-Yi; Meng, Hsin-Fei; Yu, Yi-Hsiang; Yang, Chia-Ming; Liao, Hua-Hsien; Horng, Sheng-Fu; Hsu, Chian-Shu

    2007-04-01

    A highly efficient blue polymer light-emitting diode based exclusively on commercial poly(9,9-dioctylfluorene) and poly[(9,9-dioctylfluorenyl-2,7-diyl)-co-(4,4'-(N-(4-s-butylphenyl)) diphenylamine)] is demonstrated. High electroluminescent efficiency is achieved by enhancing electron currents and making devices in multilayered structures. CsF/Al is used as the efficient electron injection cathode, and the fabrication process is in the glove box to enhance electron mobility by reducing oxygen adsorption. The multilayer structure is prepared by the liquid buffer layer technique. The maximum efficiency is 2.5 cd/A at deep blue with the corresponding external quantum efficiency of 2%.

  13. Photomorphogenesis and photoassimilation in soybean and sorghum grown under broad spectrum or blue-deficient light sources

    NASA Technical Reports Server (NTRS)

    Britz, S. J.; Sager, J. C.; Knott, W. M. (Principal Investigator)

    1990-01-01

    The role of blue light in plant growth and development was investigated in soybean (Glycine max [L.] Merr. cv Williams) and sorghum (Sorghum bicolor [L.] Moench. cv Rio) grown under equal photosynthetic photon fluxes (approximately 500 micromoles per square meter per second) from broad spectrum daylight fluorescent or blue-deficient, narrow-band (589 nanometers) low pressure sodium (LPS) lamps. Between 14 and 18 days after sowing, it was possible to relate adaptations in photosynthesis and leaf growth to dry matter accumulation. Soybean development under LPS light was similar in several respects to that of shaded plants, consistent with an important role for blue light photoreceptors in regulation of growth response to irradiance. Thus, soybeans from LPS conditions partitioned relatively more growth to leaves and maintained higher average leaf area ratios (mean LAR) that compensated lower net assimilation rates (mean NAR). Relative growth rates were therefore comparable to plants from daylight fluorescent lamps. Reductions in mean NAR were matched by lower rates of net photosynthesis (A) on an area basis in the major photosynthetic source (first trifoliolate) leaf. Lower A in soybean resulted from reduced leaf dry matter per unit leaf area, but lower A under LPS conditions in sorghum correlated with leaf chlorosis and reduced total nitrogen (not observed in soybean). In spite of a lower A, mean NAR was larger in sorghum from LPS conditions, resulting in significantly greater relative growth rates (mean LAR was approximately equal for both light conditions). Leaf starch accumulation rate was higher for both species and starch content at the end of the dark period was elevated two- and three-fold for sorghum and soybean, respectively, under LPS conditions. Possible relations between starch accumulation, leaf export, and plant growth in response to spectral quality were considered.

  14. Symmetry-Breaking Charge Transfer of Visible Light Absorbing Systems: Zinc Dipyrrins

    PubMed Central

    2015-01-01

    Zinc dipyrrin complexes with two identical dipyrrin ligands absorb strongly at 450–550 nm and exhibit high fluorescence quantum yields in nonpolar solvents (e.g., 0.16–0.66 in cyclohexane) and weak to nonexistent emission in polar solvents (i.e., <10–3, in acetonitrile). The low quantum efficiencies in polar solvents are attributed to the formation of a nonemissive symmetry-breaking charge transfer (SBCT) state, which is not formed in nonpolar solvents. Analysis using ultrafast spectroscopy shows that in polar solvents the singlet excited state relaxes to the SBCT state in 1.0–5.5 ps and then decays via recombination to the triplet or ground states in 0.9–3.3 ns. In the weakly polar solvent toluene, the equilibrium between a localized excited state and the charge transfer state is established in 11–22 ps. PMID:25270268

  15. Morphological, Photosynthetic, and Physiological Responses of Rapeseed Leaf to Different Combinations of Red and Blue Lights at the Rosette Stage.

    PubMed

    Shengxin, Chang; Chunxia, Li; Xuyang, Yao; Song, Chen; Xuelei, Jiao; Xiaoying, Liu; Zhigang, Xu; Rongzhan, Guan

    2016-01-01

    Rapeseed (Brassica napus L.) is sensitive to light quality. The factory production of rapeseed seedlings for vegetable use and for transplanting in the field requires an investigation of the responses of rapeseed to light quality. This study evaluated the responses of the leaf of rapeseed (cv. "Zhongshuang 11") to different ratios of red-photonflux (RPF) and blue-photonflux (BPF) from light emitting diodes (LEDs). The treatments were set as monochromatic lights, including 100R:0B% and 0R:100B%, and compound lights (CLs), including 75R:25B%, 50R:50B%, and 25R:75B%. The total photonflux in all of the treatments was set as 550 μmolm(-2)s(-1). With an increase of BPF, the rapeseed leaves changed from wrinkled blades and down-rolled margins to flat blades and slightly up-rolled margins, and the compact degree of palisade tissue increased. One layer of the cells of palisade tissue was present under 100R:0B%, whereas two layers were present under the other treatments. Compared to 100R:0B%, 0R:100B% enhanced the indexes of leaf thickness, leaf mass per area (LMA), stomatal density, chlorophyll (Chl) content per weight and photosynthetic capacity (P max), and the CLs with high BPF ratios enhanced these indexes. However, the 100R:0B% and CLs with high RPF ratios enhanced the net photosynthetic rate (P n). The leaves under the CLs showed growth vigor, whereas the leaves under 100R:0B% or 0R:100B% were stressed with a low F v/F m (photosynthetic maximum quantum yield) and a high content of [Formula: see text] and H2O2. The top second leaves under 100R:0B% or 0R:100B% showed stress resistance responses with a high activity of antioxidase, but the top third leaves showed irreversible damage and inactivity of antioxidase. Our results showed that the rapeseed leaves grown under 0R:100B% or CLs with a high BPF ratio showed higher ability to utilize high photonflux, while the leaves grown under 100R:0B% or CLs with a low BPF ratio showed higher efficiency in utilizing low

  16. Morphological, Photosynthetic, and Physiological Responses of Rapeseed Leaf to Different Combinations of Red and Blue Lights at the Rosette Stage

    PubMed Central

    Shengxin, Chang; Chunxia, Li; Xuyang, Yao; Song, Chen; Xuelei, Jiao; Xiaoying, Liu; Zhigang, Xu; Rongzhan, Guan

    2016-01-01

    Rapeseed (Brassica napus L.) is sensitive to light quality. The factory production of rapeseed seedlings for vegetable use and for transplanting in the field requires an investigation of the responses of rapeseed to light quality. This study evaluated the responses of the leaf of rapeseed (cv. “Zhongshuang 11”) to different ratios of red-photonflux (RPF) and blue-photonflux (BPF) from light emitting diodes (LEDs). The treatments were set as monochromatic lights, including 100R:0B% and 0R:100B%, and compound lights (CLs), including 75R:25B%, 50R:50B%, and 25R:75B%. The total photonflux in all of the treatments was set as 550 μmolm−2s−1. With an increase of BPF, the rapeseed leaves changed from wrinkled blades and down-rolled margins to flat blades and slightly up-rolled margins, and the compact degree of palisade tissue increased. One layer of the cells of palisade tissue was present under 100R:0B%, whereas two layers were present under the other treatments. Compared to 100R:0B%, 0R:100B% enhanced the indexes of leaf thickness, leaf mass per area (LMA), stomatal density, chlorophyll (Chl) content per weight and photosynthetic capacity (Pmax), and the CLs with high BPF ratios enhanced these indexes. However, the 100R:0B% and CLs with high RPF ratios enhanced the net photosynthetic rate (Pn). The leaves under the CLs showed growth vigor, whereas the leaves under 100R:0B% or 0R:100B% were stressed with a low Fv/Fm (photosynthetic maximum quantum yield) and a high content of O2.- and H2O2. The top second leaves under 100R:0B% or 0R:100B% showed stress resistance responses with a high activity of antioxidase, but the top third leaves showed irreversible damage and inactivity of antioxidase. Our results showed that the rapeseed leaves grown under 0R:100B% or CLs with a high BPF ratio showed higher ability to utilize high photonflux, while the leaves grown under 100R:0B% or CLs with a low BPF ratio showed higher efficiency in utilizing low photonflux. Under

  17. Chromophore absorbance change quantification in tissue during low-level light therapy

    NASA Astrophysics Data System (ADS)

    Huynh, Daniel; Chung, Christine; Qian, Li; Lilge, Lothar

    2012-03-01

    Low Level Light Therapy (LLLT) has been implicated to stimulate tissue, promoting healing and reducing pain. One of the potential pathways stimulated by LLLT relates to the electron transport chain, where photon quantum energy can induce a change in the biochemical reactions within the cell. The aim of this study is to assess the feasibility to exploit light additionally as a diagnostic tool to determine tissue physiological states, particularly in quantifying the changes in redox states of Cytochrome C as a result of induced LLLT biochemical reactions.

  18. Fabrication and characterization of nitride-based blue light-emitting diodes on moth-eye patterned sapphire substrate (MPSS)

    NASA Astrophysics Data System (ADS)

    Tsuchiya, T.; Umeda, S.; Sowa, Mihoko; Kondo, T.; Kitano, T.; Mori, M.; Suzuki, A.; Naniwae, K.; Sekine, H.; Iwaya, M.; Takeuchi, T.; Kamiyama, S.; Akasaki, I.

    2013-03-01

    The fabrication procedure of a moth-eye patterned sapphire substrate (MPSS), which can enhance the light extraction efficiency of nitride-based light emitting diodes (LEDs) has been examined. The optimization of surface morphology after the etching of the MPSS for high-quality GaN growth was also performed. Then, we fabricated MPSS samples with a fixed pitch of 460nm, and corn height ranging from 50 to 350nm. The light extraction efficiency of blue-LEDs grown on a series of MPSS was enhanced about 1.4 times compared with the devices grown on a flat sapphire substrate. We found that if corn height exceeds 150nm, the MPSS effect is sufficiently observed.

  19. The plasma membrane-associated NADH oxidase (ECTO-NOX) of mouse skin responds to blue light

    NASA Technical Reports Server (NTRS)

    Morre, D. James; Morre, Dorothy M.

    2003-01-01

    NADH oxidases of the external plasma membrane surface (ECTO-NOX proteins) are characterized by oscillations in activity with a regular period length of 24 min. Explants of mouse skin exhibit the oscillatory activity as estimated from the decrease in A(340) suggesting that individual ECTO-NOX molecules must somehow be induced to function synchronously. Transfer of explants of mouse skin from darkness to blue light (495 nm, 2 min, 50 micromol m(-1) s(-1)) resulted in initiation of a new activity maximum (entrainment) with a midpoint 36 min after light exposure followed by maxima every 24 min thereafter. Addition of melatonin resulted in a new maximum 24 min after melatonin addition. The findings suggest that the ECTO-NOX proteins play a central role in the entrainment of the biological clock both by light and by melatonin.

  20. Predictive modeling of the current density and radiative recombination in blue polymer-based light-emitting diodes

    NASA Astrophysics Data System (ADS)

    van Mensfoort, S. L. M.; Billen, J.; Carvelli, M.; Vulto, S. I. E.; Janssen, R. A. J.; Coehoorn, R.

    2011-03-01

    The results of a combined experimental and modeling study of charge transport, recombination and light emission in blue organic light-emitting diodes (OLEDs) based on a polyfluorene derivative are presented. It is shown that the measured temperature-dependent current-voltage curves and the voltage-dependent current efficiency are accurately described using an OLED device model that is based on the separately determined unipolar electron and hole mobility functions. The recombination rate is calculated using the Langevin formula, including recombination of holes with free as well as trapped electrons. The light emission is obtained from the exciton formation profile using independently determined values of the exciton radiative decay probability, the average dipole orientation, and assuming a fraction of singlet excitons ηS =​(22±3)%, close to the quantum-statistical value. No additional free parameter is used. This shows that predictive one-dimensional device modeling of OLEDs is feasible.

  1. Productivity, absorbed photosynthetically active radiation, and light use efficiency in crops: implications for remote sensing of crop primary production.

    PubMed

    Gitelson, Anatoly A; Peng, Yi; Arkebauer, Timothy J; Suyker, Andrew E

    2015-04-01

    Vegetation productivity metrics such as gross primary production (GPP) at the canopy scale are greatly affected by the efficiency of using absorbed radiation for photosynthesis, or light use efficiency (LUE). Thus, close investigation of the relationships between canopy GPP and photosynthetically active radiation absorbed by vegetation is the basis for quantification of LUE. We used multiyear observations over irrigated and rainfed contrasting C3 (soybean) and C4 (maize) crops having different physiology, leaf structure, and canopy architecture to establish the relationships between canopy GPP and radiation absorbed by vegetation and quantify LUE. Although multiple LUE definitions are reported in the literature, we used a definition of efficiency of light use by photosynthetically active "green" vegetation (LUE(green)) based on radiation absorbed by "green" photosynthetically active vegetation on a daily basis. We quantified, irreversible slowly changing seasonal (constitutive) and rapidly day-to-day changing (facultative) LUE(green), as well as sensitivity of LUE(green) to the magnitude of incident radiation and drought events. Large (2-3-fold) variation of daily LUE(green) over the course of a growing season that is governed by crop physiological and phenological status was observed. The day-to-day variations of LUE(green) oscillated with magnitude 10-15% around the seasonal LUE(green) trend and appeared to be closely related to day-to-day variations of magnitude and composition of incident radiation. Our results show the high variability of LUE(green) between C3 and C4 crop species (1.43 g C/MJ vs. 2.24 g C/MJ, respectively), as well as within single crop species (i.e., maize or soybean). This implies that assuming LUE(green) as a constant value in GPP models is not warranted for the crops studied, and brings unpredictable uncertainties of remote GPP estimation, which should be accounted for in LUE models. The uncertainty of GPP estimation due to facultative and

  2. Light pollution modelling the UK Highways Agency new environmental policy, inc. astronomical impact of blue-rich LED luminaires.

    NASA Astrophysics Data System (ADS)

    Baddiley, Christopher James

    2015-08-01

    The Highways Agency are replacing their policy of full cut off class G6 road lighting specification on motorways (originally based on the author’s work), and are adopting a categorised environmental impact based point system that can accommodate technical advances, such as LED lighting. The Skyglow component of this will be based on the modelling of skyglow versus cut-off angle, developed for determining the relative light pollution environmental impact of different streetlight designs, by the author. Further modelling has been done concerning the effect of LED lighting, which potentially, has highly directional properties. But increasingly used blue rich colour temperatures may increase skyglow by 5 fold, compared to traditional lighting. This is due to enhanced reflection of vegetation and greatly increased atmospheric molecular Rayleigh scattering; a potential astronomical environmental disaster.Prior to this, the author carried out a dark sky survey of the Malvern Hills area of outstanding natural beauty (AONB), relating it to the same light pollution model. The results confirm the general predictions of the model and also clearly illustrate the relative significance of different designs of light sources at different distances, to the dark sky environment.The paper also briefly describes the results from the same model adapted to study the night-time environmental impact of a proposed very large sea based wind farm project in the English Channel, as a part of the planning process.

  3. Absorbance detector based on a deep UV light emitting diode for narrow-column HPLC.

    PubMed

    Bui, Duy Anh; Bomastyk, Benjamin; Hauser, Peter C

    2013-10-01

    A detector for miniaturized HPLC based on deep UV emitting diodes and UV photodiodes was constructed. The measurement is accomplished by the transverse passage of the radiation from the light-emitting diode (LED) through fused-silica tubing with an internal diameter of 250 μm. The optical cell allows flexible alignment of the LED, tubing, and photodiode for optimization of the light throughput and has an aperture to block stray light. A beam splitter was employed to direct part of the emitted light to a reference photodiode and the Lambert-Beer law was emulated with a log-ratio amplifier circuitry. The detector was tested with two LEDs with emission bands at 280 and 255 nm and showed noise levels as low as 0.25 and 0.22 mAU, respectively. The photometric device was employed successfully in separations using a column of 1 mm inner diameter in isocratic as well as gradient elution. Good linearities over three orders of magnitude in concentration were achieved, and the precision of the measurements was better than 1% in all cases. Detection down to the low micromolar range was possible. PMID:23893947

  4. Photoprotection of reaction centers: thermal dissipation of absorbed light energy vs charge separation in lichens.

    PubMed

    Heber, Ulrich; Soni, Vineet; Strasser, Reto J

    2011-05-01

    During desiccation, fluorescence emission and stable light-dependent charge separation in the reaction centers (RCs) of photosystem II (PSII) declined strongly in three different lichens: in Parmelia sulcata with an alga as the photobiont, in Peltigera neckeri with a cyanobacterium and in the tripartite lichen Lobaria pulmonaria. Most of the decline of fluorescence was caused by a decrease in the quantum efficiency of fluorescence emission. It indicated the activation of photoprotective thermal energy dissipation. Photochemical activity of the RCs was retained even after complete desiccation. It led to light-dependent absorption changes and found expression in reversible increases in fluorescence or in fluorescence quenching. Lowering the temperature changed the direction of fluorescence responses in P. sulcata. The observations are interpreted to show that reversible light-induced increases in fluorescence emission in desiccated lichens indicate the functionality of the RCs of PSII. Photoprotection is achieved by the drainage of light energy to dissipating centers outside the RCs before stable charge separation can take place. Reversible quenching of fluorescence by strong illumination is suggested to indicate the conversion of the RCs from energy conserving to energy dissipating units. This permits them to avoid photoinactivation. On hydration, re-conversion occurs to energy-conserving RCs. PMID:21029105

  5. Blue Laser Light Increases Perfusion of a Skin Flap Via Release of Nitric Oxide from Hemoglobin

    PubMed Central

    Mittermayr, Rainer; Osipov, Anatoly; Piskernik, Christina; Haindl, Susanne; Dungel, Peter; Weber, Carina; Vladimirov, Yuri A; Redl, Heinz; Kozlov, Andrey V

    2007-01-01

    It has recently been shown that nitrosyl complexes of hemoglobin (NO-Hb) are sensitive to low-level blue laser irradiation, suggesting that laser irradiation can facilitate the release of biologically active nitric oxide (NO), which can affect tissue perfusion. The aim of this study was to evaluate the therapeutic value of blue laser irradiation for local tissue perfusion after surgical intervention. Blood was withdrawn from a rat, exposed to NO and infused back to the same rat or used for in vitro experiments. In vitro, an increase of NO-Hb levels (electron paramagnetic resonance spectroscopy) up to 15 μM in rat blood did not result in the release of detectable amounts of NO (NO selective electrode). Blue laser irradiation of NO-Hb in blood caused decomposition of NO-Hb complexes and release of free NO. Systemic infusion of NO-Hb in rats affected neither systemic circulation (mean arterial pressure) nor local tissue perfusion (Doppler blood flow imaging system). In contrast, a clear enhancement of local tissue perfusion was observed in epigastric flap when elevated NO-Hb levels in blood were combined with local He-Cd laser irradiation focused on the left epigastric artery. The enhancement of regional tissue perfusion was not accompanied by any detectable changes in systemic circulation. This study demonstrates that blue laser irradiation improves local tissue perfusion in a controlled manner stimulating NO release from NO-Hb complexes. PMID:17515954

  6. Plasmon-assisted degradation of methylene blue with Ag/AgCl/montmorillonite nanocomposite under visible light

    NASA Astrophysics Data System (ADS)

    Sohrabnezhad, Sh.; Zanjanchi, M. A.; Razavi, M.

    2014-09-01

    Metal-semiconductor compounds, such as Ag/AgX (X = Cl, Br, I), enable visible light absorption and separation of photogenerated electron-hole through surface plasmon resonance (SPR) effect. However, the electron-hole generated and separated by light are vulnerable in Ag/AgX phase because of the occurrence of secondary recombined. In order to more effectively utilize the SPR photocatalytic effect, nanoparticles are located in a matrix. In this article, Ag/AgCl nanoparticles were synthesized in montmorillonite (MMT) matrix using dispersion method and light irradiation. The structure, composition and optical properties of such material were investigated by transmission electron microscopy (TEM), UV-visible diffuse reflectance spectroscopy (UV-Vis DRS), X-ray diffraction (XRD) and FTIR. Powder X-ray diffraction showed intercalation of Ag/AgCl nanoparticles into the clay layers. The as-prepared plasmonic photocatalyst exhibited an enhanced and stable photoactivity for the degradation of methylene blue (MB) under visible light. The high activity was attributed to the surface plasmon resonance (SPR) exhibited by Ag nanoparticles on the surface of AgCl. The detection of reactive species by radical scavengers displays that rad O2- and rad OH- are the main reactive species for the degradation of MB under visible light irradiation. The studies showed that 20 min illumination under visible light can complete degradation of methylene blue (MB), and indicate a high stability of photocatalytic degradation. The mechanism of separation of the photo-generated electrons and holes at the Ag/AgCl-MMT nanocomposite was discussed.

  7. Chemical characteristics and light-absorbing property of water-soluble organic carbon in Beijing: Biomass burning contributions

    NASA Astrophysics Data System (ADS)

    Yan, Caiqing; Zheng, Mei; Sullivan, Amy P.; Bosch, Carme; Desyaterik, Yury; Andersson, August; Li, Xiaoying; Guo, Xiaoshuang; Zhou, Tian; Gustafsson, Örjan; Collett, Jeffrey L.

    2015-11-01

    Emissions from biomass burning contribute significantly to water-soluble organic carbon (WSOC) and light-absorbing organic carbon (brown carbon). Ambient atmospheric samples were collected at an urban site in Beijing during winter and summer, along with source samples from residential crop straw burning. Carbonaceous aerosol species, including organic carbon (OC), elemental carbon (EC), WSOC and multiple saccharides as well as water-soluble potassium (K+) in PM2.5 (fine particulate matter with size less than 2.5 μm) were measured. Chemical signatures of atmospheric aerosols in Beijing during winter and summer days with significant biomass burning influence were identified. Meanwhile, light absorption by WSOC was measured and quantitatively compared to EC at ground level. The results from this study indicated that levoglucosan exhibited consistently high concentrations (209 ± 145 ng m-3) in winter. Ratios of levoglucosan/mannosan (L/M) and levoglucosan/galacosan (L/G) indicated that residential biofuel use is an important source of biomass burning aerosol in winter in Beijing. Light absorption coefficient per unit ambient WSOC mass calculated at 365 nm is approximately 1.54 ± 0.16 m2 g-1 in winter and 0.73 ± 0.15 m2 g-1 in summer. Biomass burning derived WSOC accounted for 23 ± 7% and 16 ± 7% of total WSOC mass, and contributed to 17 ± 4% and 19 ± 5% of total WSOC light absorption in winter and summer, respectively. It is noteworthy that, up to 30% of total WSOC light absorption was attributed to biomass burning in significant biomass-burning-impacted summer day. Near-surface light absorption (over the range 300-400 nm) by WSOC was about ∼40% of that by EC in winter and ∼25% in summer.

  8. Effects of Photodynamic Therapy with Blue Light and Curcumin as Mouth Rinse for Oral Disinfection: A Randomized Controlled Trial

    PubMed Central

    Leite, Diego Portes Vieira; Parmesano, Thiago Nogueira; Fontana, Carla Raquel; Bagnato, Vanderlei Salvador

    2014-01-01

    Abstract Objective: The purpose of this study was to evaluate the effects of the antimicrobial photodynamic therapy (a-PDT) with blue light and curcumin on oral disinfection during the 2 h after treatment. Background data: a-PDT is a technique that can potentially affect the viability of bacterial cells, with selective action targeting only areas with photosensitizer accumulation. Materials and methods: A randomized controlled trial was undertaken. Twenty-seven adults were randomly divided into three groups: (1) the PDT group, which was treated with the drug, curcumin, and blue light (n=9); (2) the light group, which was treated only with the blue light, and no drug (n=9) and; (3) the curcumin group, which was treated only with the drug, curcumin, and no light (n=9). The irradiation parameters were: blue light-emitting diode (LED) illumination (455±30 nm), 400 mW of average optical power, 5 min of application, illumination area of 0.6 cm2, 600 mW/cm2 of intensity, and 200 J/cm2 of fluence. A curcumin concentration of 30 mg/L was used. The saliva samples were collected for bacterial counts at baseline and after the experimental phases (immediately after treatment, and 1 and 2 h after treatment). Serial dilutions were performed, and the resulting samples were cultured on blood agar plates in microaerophilic conditions. The number of colony-forming units (CFU) was determined. Results: The PDT group showed a significant reduction of CFU immediately after treatment (post-treatment) with PDT (5.71±0.48, p=0.001), and 1 h (5.14±0.92, p=0.001) and 2 h (5.35±0.76, p=0.001) after treatment, compared with pretreatment (6.61±0.82). There were no significant changes for the light group. The curcumin group showed a significant increase of CFU 1 h after treatment (6.77±0.40, p=0.02) compared with pretreatment (5.57±0.91) falling to baseline values at 2 h after treatment (5.58±0.70). Conclusions: The PDT group showed significant difference in

  9. Blue-Violet Light Irradiation Dose Dependently Decreases Carotenoids in Human Skin, Which Indicates the Generation of Free Radicals

    PubMed Central

    Vandersee, Staffan; Beyer, Marc; Lademann, Juergen; Darvin, Maxim E.

    2015-01-01

    In contrast to ultraviolet and infrared irradiation, which are known to facilitate cutaneous photoaging, immunosuppression, or tumour emergence due to formation of free radicals and reactive oxygen species, potentially similar effects of visible light on the human skin are still poorly characterized. Using a blue-violet light irradiation source and aiming to characterize its potential influence on the antioxidant status of the human skin, the cutaneous carotenoid concentration was measured noninvasively in nine healthy volunteers using resonance Raman spectroscopy following irradiation. The dose-dependent significant degradation of carotenoids was measured to be 13.5% and 21.2% directly after irradiation at 50 J/cm² and 100 J/cm² (P < 0.05). The irradiation intensity was 100 mW/cm². This is above natural conditions; the achieved doses, though, are acquirable under natural conditions. The corresponding restoration lasted 2 and 24 hours, respectively. The degradation of cutaneous carotenoids indirectly shows the amount of generated free radicals and especially reactive oxygen species in human skin. In all volunteers the cutaneous carotenoid concentration dropped down in a manner similar to that caused by the infrared or ultraviolet irradiations, leading to the conclusion that also blue-violet light at high doses could represent a comparably adverse factor for human skin. PMID:25741404

  10. Tunable ultraviolet and blue light generation from Nd:YAB random laser bolstered by second-order nonlinear processes

    PubMed Central

    Moura, André L.; Carreño, Sandra J. M.; Pincheira, Pablo I. R.; Fabris, Zanine V.; Maia, Lauro J. Q.; Gomes, Anderson S. L.; de Araújo, Cid B.

    2016-01-01

    Ultraviolet and blue light were obtained by nonlinear frequency conversion in a random laser (RL) based on Nd0.10Y0.90Al3(BO3)4 nanocrystalline powder. RL operation at 1062 nm, due to the 4F3/2 → 4I11/2 transition of neodymium ions (Nd3+), was achieved by exciting the Nd3+ with a tunable beam from 680 to 920 nm covering the ground state absorption transitions to the 4F9/2, (4F7/2,4S3/2), (4F5/2,2H9/2), and 4F3/2 states. Light from 340 to 460 nm was obtained via the second-harmonic generation of the excitation beam while tunable blue light, from 417 to 486 nm, was generated by self-sum-frequency mixing between the excitation beam and the RL emission. PMID:27250647

  11. Tunable ultraviolet and blue light generation from Nd:YAB random laser bolstered by second-order nonlinear processes.

    PubMed

    Moura, André L; Carreño, Sandra J M; Pincheira, Pablo I R; Fabris, Zanine V; Maia, Lauro J Q; Gomes, Anderson S L; de Araújo, Cid B

    2016-01-01

    Ultraviolet and blue light were obtained by nonlinear frequency conversion in a random laser (RL) based on Nd0.10Y0.90Al3(BO3)4 nanocrystalline powder. RL operation at 1062 nm, due to the (4)F3/2 → (4)I11/2 transition of neodymium ions (Nd(3+)), was achieved by exciting the Nd(3+) with a tunable beam from 680 to 920 nm covering the ground state absorption transitions to the (4)F9/2, ((4)F7/2,(4)S3/2), ((4)F5/2,(2)H9/2), and (4)F3/2 states. Light from 340 to 460 nm was obtained via the second-harmonic generation of the excitation beam while tunable blue light, from 417 to 486 nm, was generated by self-sum-frequency mixing between the excitation beam and the RL emission. PMID:27250647

  12. Optical Properties of Blue-Light-Emitting (Ca,Sr)Mg2Si3O9:Eu2+ Phosphor

    NASA Astrophysics Data System (ADS)

    Lee, Hyun Ju; Choi, Sung Hwan; Kim, Kyung Pil; Shin, Hyun Ho; Yoo, Jae Soo

    2010-10-01

    For light-emitting diode (LED) excitation at 400 nm, the optical properties of a Eu2+-activated CaO-SrO-MgO-SiO2 material system were investigated. All the materials were synthesized by solid state reaction. In particular, (Ca,Sr)Mg2Si3O9:Eu2+, which has the same crystal structure as CaMgSi2O6, was found to be promising as a blue-light-emitting phosphor for near UV LED application. The luminance intensity was optimized by controlling the Eu2+ concentration and the composition of the host lattice. The ratio of calcium ions to strontium ions was a convenient parameter for adjusting the maximum excitation peak to 400 nm, which is favorable for near UV LED excitation. The highest luminance intensity of Ca1-x-ySryMg2Si3O9:Eux2+ under 405 nm excitation was achieved at the Eu2+ concentration of x=0.01 and a Sr2+ concentration of y=0.3. The luminance intensity of (Ca,Sr)Mg2Si3O9:Eu2+ was found to be superior to that of a commercial blue-light-emitting BaMgAl10O17:Eu2+ phosphor, which is used for near-UV LED excitation.

  13. Tunable ultraviolet and blue light generation from Nd:YAB random laser bolstered by second-order nonlinear processes

    NASA Astrophysics Data System (ADS)

    Moura, André L.; Carreño, Sandra J. M.; Pincheira, Pablo I. R.; Fabris, Zanine V.; Maia, Lauro J. Q.; Gomes, Anderson S. L.; de Araújo, Cid B.

    2016-06-01

    Ultraviolet and blue light were obtained by nonlinear frequency conversion in a random laser (RL) based on Nd0.10Y0.90Al3(BO3)4 nanocrystalline powder. RL operation at 1062 nm, due to the 4F3/2 → 4I11/2 transition of neodymium ions (Nd3+), was achieved by exciting the Nd3+ with a tunable beam from 680 to 920 nm covering the ground state absorption transitions to the 4F9/2, (4F7/2,4S3/2), (4F5/2,2H9/2), and 4F3/2 states. Light from 340 to 460 nm was obtained via the second-harmonic generation of the excitation beam while tunable blue light, from 417 to 486 nm, was generated by self-sum-frequency mixing between the excitation beam and the RL emission.

  14. The Trichoderma atroviride cryptochrome/photolyase genes regulate the expression of blr1-independent genes both in red and blue light.

    PubMed

    García-Esquivel, Mónica; Esquivel-Naranjo, Edgardo U; Hernández-Oñate, Miguel A; Ibarra-Laclette, Enrique; Herrera-Estrella, Alfredo

    2016-04-01

    Quantitative transcriptome analysis led to the identification of 331 transcripts regulated by white light. Evaluation of the response to white light in mutants affected in the previously characterized blue-light receptor Blr1, demonstrated the existence of both Blr1-dependent and independent responses. Functional categorization of the light responsive genes indicated the effect of light on regulation of various transcription factors, regulators of chromatin structure, signaling pathways, genes related to different kinds of stress, metabolism, redox adjustment, and cell cycle among others. In order to establish the participation of other photoreceptors, gene expression was validated in response to different wavelengths. Gene regulation by blue and red light suggests the involvement of several photoreceptors in integrating light signals of different wavelengths in Trichoderma atroviride. Functional analysis of potential blue light photoreceptors suggests that several perception systems for different wavelengths are involved in the response to light. Deletion of cry1, one of the potential photoreceptors, resulted in severe reduction in the photoreactivation capacity of the fungus, as well as a change in gene expression under blue and red light. PMID:27020152

  15. Functions of laser light, laser-absorbing dye, and immunoadjuvants in photodynamic immunotherapy

    NASA Astrophysics Data System (ADS)

    Chen, Wei R.; Liu, Hong; Bartels, Kenneth E.; Nordquist, Robert E.

    2000-10-01

    Photo Dynamic Immuno Therapy (PDIT) is a novel approach for treatment of metastatic tumors. It involves an intratumor administration of a laser-absorbing dye and an immunoadjuvant, followed by a non-invasive laser irradiation. Previous studies using a novel immunoadjuvant, glycated chitosan, showed the effect of the treatment on a metastatic breast tumor in rats, including the eradication of treated primary tumors, regression of untreated metastases, and the evidence of immune responses induced by the treatment. To further understand the mechanism of PDIT, tumor-bearing rats were treated by different combinations of the three PDIT components. The rat survival rates and profiles of primary and metastatic tumors, after treatment by individual component and different combinations of components, were analyzed. All the experimental groups without using immunoadjuvant showed none or little positive effect. The use of glycated chitosan, either by itself or in combination of other components, has showed that among the concentrations of 0.5%, 1% and 2%, glycated chitosan was most effective at 1% in PDIT. Another immunoadjuvant, incomplete Freund's adjuvant, was also used and the results were compared with that of using glycated chitosan. PDIT was applied to a different tumor model- Met-Lu, a prostatic tumor with lung metastases in male rats and the preliminary results are reported.

  16. In vitro and in vivo antimicrobial activity of combined therapy of silver nanoparticles and visible blue light against Pseudomonas aeruginosa.

    PubMed

    Nour El Din, Suzanne; El-Tayeb, Tarek A; Abou-Aisha, Khaled; El-Azizi, Mohamed

    2016-01-01

    Silver nanoparticles (AgNPs) have been used as potential antimicrobial agents against resistant pathogens. We investigated the possible therapeutic use of AgNPs in combination with visible blue light against a multidrug resistant clinical isolate of Pseudomonas aeruginosa in vitro and in vivo. The antibacterial activity of AgNPs against P. aeruginosa (1×10(5) colony forming unit/mL) was investigated at its minimal inhibitory concentration (MIC) and sub-MIC, alone and in combination with blue light at 460 nm and 250 mW for 2 hours. The effect of this combined therapy on the treated bacteria was then visualized using transmission electron microscope. The therapy was also assessed in the prevention of biofilm formation by P. aeruginosa on AgNP-impregnated gelatin biopolymer discs. Further, in vivo investigations were performed to evaluate the efficacy of the combined therapy to prevent burn-wound colonization and sepsis in mice and, finally, to treat a real infected horse with antibiotic-unresponsive chronic wound. The antimicrobial acti