WorldWideScience

Sample records for blue light exposure

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

    Science.gov (United States)

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

    2016-01-01

    Increasing evidence points to associations between light-dark exposure patterns, feeding behavior, and metabolism. This study aimed to determine the acute effects of 3 hours of morning versus evening blue-enriched light exposure compared to dim light on hunger, metabolic function, and physiological arousal. Nineteen healthy adults completed this 4-day inpatient protocol under dim light conditions (<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

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

    Science.gov (United States)

    Purawijaya, Dandri Aly; Fitri, Lulu Lusianti; Suprijanto

    2015-09-01

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

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

    Directory of Open Access Journals (Sweden)

    Jacques Taillard

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

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

    Science.gov (United States)

    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

  5. Occupational exposure of welders to ultraviolet and "blue light" radiation emitted during TIG and MMA welding based on field measuremants

    Directory of Open Access Journals (Sweden)

    Agnieszka Wolska

    2013-02-01

    Full Text Available Background: The aim of the study was to present the results of welders' occupational exposure to "blue light" and UV radiation carried out at industrial workstations during TIG and MMA welding. Materials and methods: Measurements were performed at 13 workstations (TIG welding: 6; MMA welding: 7, at which different welding parameters and materials were used. The radiation level was measured using a wide-range radiometer and a set of detectors, whose spectral responses were adequately fit to particular hazard under study. The measurement points corresponded with the location of eye and hand. Results: The highest values of eye irradiance were found for aluminum TIG welding. Effective irradiance of actinic UV was within the range Es = 7.79-37.6 W/m2; UVA total irradiance, EUVA = 18-53.1 W/m2 and effective blue-light irradiance EB = 35-67 W/m2. The maximum allowance time ranged from 1.7 to 75 s, which means that in some cases even unintentional very short eye exposure can exceed MPE. Conclusions: The influence of welded material and the type of electrode coating on the measured radiation level were evidenced. The exceeded value of MPE for photochemical hazard arising for the eyes and skin was found at all measured workstations. Welders should use appropriately the eye and face protective equipment and avoid direct staring at welding arc when starting an arcwelding operation. Besides, the lack of head and neck skin protection can induce acute and chronic harmful health effects. Therefore, an appropriate wear of personal protective equipment is essential for welders' health. Med Pr 2013;64(1:69–82

  6. [KINETICS OF PHOTO-INDUCED FREE RADICALS IN THE HUMAN HAIR CHESTNUT COLOR AFTER SHORT PERIODS OF RED, GREEN, BLUE AND WHITE LIGHT EXPOSURE].

    Science.gov (United States)

    Tskhvediani, N; Chikvaidze, E; Tsibadze, A; Kvachadze, I; Gogoladze, T; Katsitadze, A

    2016-04-01

    The aim of the study was to investigate the kinetics of photo-induced free radicals in the human hair chestnut color with short-term exposure to visible light in different frequency ranges. Studies carried out on human volunteers aged 17-21 years (n=37). Hairs of volunteers of the study were not treated with dyes and other active cosmetic preparations. Hairs bundled in a bun had a length - 1.5 cm, weight - 40 mg. At the beginning background EPR-spectrum of a sample was measured and then hairs were irradiated with visible light (blue, green, red and white) of different wavelength subsequently; exposure duration - 60 minutes; after the exposure the kinetics of photo-induced free radicals was measured within 60 minutes. The radiation source was selected LED array of the four crystals that provides a nearly monochromatic radiation spectrum having no parasitic infrared and ultraviolet radiations. The studies give a reason to assume that the impact on hairs by visible electromagnetic rays a leading factor is their frequency characteristics: on the one hand - the proximity of the blue light to ultraviolet radiation, and on the other - the red light to the infrared range. PMID:27249443

  7. Biological behaviour of buccal cells exposed to blue light

    International Nuclear Information System (INIS)

    Blue light is used in dental practise to cure resin-based materials, but the path of the light often includes oral tissues such as gingival tissues. While adverse effects of blue light exposure on cells - such as retina cells - are well known, few studies have investigated the impact of blue light exposure on oral cells. The aim of the present in vitro study was to assess the biological effects of blue light emitted by two dental curing devices (a plasma-arc and a light-emitting diode curing unit) on human gingival fibroblasts. Light intensities and light-induced temperature rise were respectively measured with a radiometer and a thermocouple. Cellular response to blue light exposure was assessed by the observation of cell morphology (scanning electron microscopy) and the estimation of cell mitochondrial activity (MTT assay). Light intensities measured at the clinical distance were 488 ± 42 mW/cm2 for the plasma-arc unit and ranged from 61 ± 5 to 140 ± 16 mW/cm2 for the light-emitting diodes unit, according to the curing program used. The highest temperature rise was 0.5 and 3.5 deg. C for exposure to the plasma-arc light and to the light-emitting diodes light, respectively. Results showed no differences between exposed- and non-exposed cells in regards to cell morphology. However, cells exposed to blue light presented an increased mitochondrial activity compared to control cells (non-exposed), and mostly those exposed to plasma-arc light

  8. Blue enhanced light sources: opportunities and risks

    Science.gov (United States)

    Lang, Dieter

    2012-03-01

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

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

    International Nuclear Information System (INIS)

    Full text: Halogen curing lights are the most frequently used polymerization source in dental offices. Light-cured bonding systems have become increasingly popular among clinicians because they offer a number of advantages over self-cured adhesives. The effort to increase polymerization quality releases the commercially available high power light density dental curing units. Emitted visible blue light belongs to the range of nonionizing radiation. Common concern in both, patients and dentist grows with regard to the unfavorable effects on the pulp tissue. The aim of study was to evaluate the time and dose dependence effect of halogen light curing unit (Elipar TriLight, ESPE Dental AG, Germany) at the disposed condition modes in vitro. A quartz-tungsten-halogen light source emits radiation of the wavelengths between 400 and 515 nm. This halogen blue light source operates in the three illumination modes, medium (M), exponential (E) and standard (S), and five illumination times. The total irradiance or the light intensity was measured by the light intensity control area on the control panel of device and mean light intensity given by manufacturer was 800 m W/cm2. Continuous culture of V79 cells was illuminated in triplicate. The influence of medium mode (M), exponential (E) and standard (S) illumination during 20, 40 and 80 sec on the cell viability, colony forming ability and proliferation of V79 cell culture was investigated. Trypan blue exclusion test was used to determine cell viability, both, in the treated and control cell samples. Colony forming ability was assessed for each exposure time and mode by colony count on post-exposure day 7. Cell proliferation was determined by cell counts for each time and mode of exposure during five post-exposure days. Statistical difference were determined at p<0.05 (Statistica 7.0, StatSoft Inc., USA). Viability of cells was not affected by blue light in view of exposure time and modes. Regardless to exposure or illumination

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

    Science.gov (United States)

    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).

  11. Blue light hazards for ocular lesions

    International Nuclear Information System (INIS)

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

  12. Approaches to blue light emitting polymers

    International Nuclear Information System (INIS)

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

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

    Science.gov (United States)

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

    2016-01-01

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

  14. Blue-green and green phosphors for lighting applications

    Science.gov (United States)

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

    2012-12-11

    Embodiments of the present techniques provide a related family of phosphors that may be used in lighting systems to generate blue or blue-green light. The phosphors include systems having a general formula of: ((Sr.sub.1-zM.sub.z).sub.1-(x+w)A.sub.wCe.sub.x).sub.3(Al.sub.1-ySi.s- ub.y)O.sub.4+y+3(x-w)F.sub.1-y-3(x-w) (I), wherein 0phosphors made accordingly to these formulations maintain emission intensity across a wide range of temperatures. The phosphors may be used in lighting 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.

  15. Environmental blue light prevents stress in the fish Nile tilapia

    OpenAIRE

    Volpato G.L.; Barreto R.E.

    2001-01-01

    The present study aimed to test the effects of blue, green or white light on the stress response of the Nile tilapia, Oreochromis niloticus (L.). Each color was tested on two groups of isolated adult Nile tilapia (8 replicates each): one being subjected to confinement stress, and the other not (control). A different environmental color was imposed on each compartment by covering the light source with cellophane of the respective color (green or blue; no cellophane was used for white light). T...

  16. Visual functional effects of constant blue light in a retinal degenerate rat model

    OpenAIRE

    Thomas, BB; Seiler, MJ; Aramant, RB; Samant, D; Qiu, G; Vyas, N; Arai, S.; Chen, Z.; Sadda, SR

    2007-01-01

    Retinal degenerative conditions increase susceptibility to light damage, but rapid retinal degeneration (RD) models show less susceptibility to cyclic dim light. We investigated whether constant blue light (BL) exposure can eliminate the residual visual responses in a comparatively rapid RD rat model. Pigmented rhodopsin mutant S334ter line-3 rat pups (21 days old) were exposed for 5-6 consecutive days to constant BL. Visual behavior was evaluated with an optokinetic head tracking apparatus. ...

  17. Photodynamic effect of light-emitting diode light on cell growth inhibition induced by methylene blue

    Indian Academy of Sciences (India)

    Lílian S Peloi; Rafael R S Soares; Carlos E G Biondo; Vagner R Souza; Noboru Hioka; Elza Kimura

    2008-06-01

    The aim of this study was to propose the use of red light-emitting diode (LED) as an alternative light source for methylene blue (MB) photosensitizing effect in photodynamic therapy (PDT). Its effectiveness was tested against Staphylococcus aureus (ATCC 26923), Escherichia coli (ATCC 26922), Candida albicans (ATCC 90028) and Artemia salina. The maximum absorption of the LED lamps was at a wavelength of 663 nm, at intensities of 2, 4, 6 and 12 J.cm–2 for 10, 20, 30 and 60 min of exposure, respectively. Assays with and without LED exposure were carried out in plates containing MB at concentrations of 7 to 140.8 M for microorganisms and 13.35 to 668.5 M for microorganisms or microcrustaceans. The LED exposure induced more than 93.05%, 93.7% and 93.33% of growth inhibition for concentrations of 42.2 M for S. aureus (D-value=12.05 min) and 35.2 M for E. coli (D-value=11.51 min) and C. albicans (D-value=12.18 min), respectively after 20 min of exposure. LED exposure for 1 h increased the cytotoxic effect of MB against A. salina from 27% to 75%. Red LED is a promising light device for PDT that can effectively inhibit bacteria, yeast and microcrustacean growth.

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

    OpenAIRE

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

    2015-01-01

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

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

    Science.gov (United States)

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

    2016-09-01

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

  20. Light-induced melatonin suppression at night after exposure to different wavelength composition of morning light.

    Science.gov (United States)

    Kozaki, Tomoaki; Kubokawa, Ayaka; Taketomi, Ryunosuke; Hatae, Keisuke

    2016-03-11

    Bright nocturnal light has been shown to suppress melatonin secretion. However, bright light exposure during the day might reduce light-induced melatonin suppression at night. The human circadian system is sensitive to short wavelength light. This study evaluated the preventive effect of different wavelengths of daytime light on light-induced melatonin suppression at night. Twelve male subjects were exposed to various light conditions (dim, white, and bluish white light) between the hours of 09:00 and 10:30 (daytime light conditions). They were then exposed to light (300lx) again between 01:00 and 02:30 (night-time light exposure). Subjects provided saliva samples before (00:55) and after night-time light exposure (02:30). A two-tailed paired t-test yielded significant decrements in melatonin concentrations after night-time light exposure under daytime dim and white light conditions. No significant differences were found in melatonin concentrations between pre- and post-night-time light exposure with bluish-white light. Present findings suggest that daytime blue light exposure has an acute preventive impact on light-induced melatonin suppression in individuals with a general life rhythm (sleep/wake schedule). These findings may be useful for implementing artificial light environments for humans in, for example, hospitals and underground shopping malls to reduce health risks. PMID:26777427

  1. Environmental blue light prevents stress in the fish Nile tilapia

    Directory of Open Access Journals (Sweden)

    Volpato G.L.

    2001-01-01

    Full Text Available The present study aimed to test the effects of blue, green or white light on the stress response of the Nile tilapia, Oreochromis niloticus (L.. Each color was tested on two groups of isolated adult Nile tilapia (8 replicates each: one being subjected to confinement stress, and the other not (control. A different environmental color was imposed on each compartment by covering the light source with cellophane of the respective color (green or blue; no cellophane was used for white light. The intensity of green, white and blue lights was 250, 590 and 250 lux, respectively. Basal plasma cortisol levels were determined for each fish prior to the experimental procedures. The fish were confined by being displaced toward one side of the aquarium using an opaque partition for 1 h both in the morning and the afternoon of the two consecutive days of the test. At the end of this 48-h period, plasma cortisol levels were measured again. Basal cortisol levels (ng/ml were similar for each group (ANOVA, F(2;42 = 0.77, P = 0.47. Thus, plasma cortisol levels were analyzed in terms of variation from their respective basal level. After confinement, plasma cortisol levels were not increased in fish submitted to a blue light environment. Thus, blue light prevents the confinement-induced cortisol response, an effect not necessarily related to light intensity.

  2. Environmental blue light prevents stress in the fish Nile tilapia.

    Science.gov (United States)

    Volpato, G L; Barreto, R E

    2001-08-01

    The present study aimed to test the effects of blue, green or white light on the stress response of the Nile tilapia, Oreochromis niloticus (L.). Each color was tested on two groups of isolated adult Nile tilapia (8 replicates each): one being subjected to confinement stress, and the other not (control). A different environmental color was imposed on each compartment by covering the light source with cellophane of the respective color (green or blue; no cellophane was used for white light). The intensity of green, white and blue lights was 250, 590 and 250 lux, respectively. Basal plasma cortisol levels were determined for each fish prior to the experimental procedures. The fish were confined by being displaced toward one side of the aquarium using an opaque partition for 1 h both in the morning and the afternoon of the two consecutive days of the test. At the end of this 48-h period, plasma cortisol levels were measured again. Basal cortisol levels (ng/ml) were similar for each group (ANOVA, F(2;42) = 0.77, P = 0.47). Thus, plasma cortisol levels were analyzed in terms of variation from their respective basal level. After confinement, plasma cortisol levels were not increased in fish submitted to a blue light environment. Thus, blue light prevents the confinement-induced cortisol response, an effect not necessarily related to light intensity. PMID:11471044

  3. Transcriptome sequencing and comparative analysis of Saccharina japonica (Laminariales, Phaeophyceae under blue light induction.

    Directory of Open Access Journals (Sweden)

    Yunyan Deng

    Full Text Available BACKGROUND: Light has significant effect on the growth and development of Saccharina japonica, but there are limited reports on blue light mediated physiological responses and molecular mechanism. In this study, high-throughput paired-end RNA-sequencing (RNA-Seq technology was applied to transcriptomes of S. japonica exposed to blue light and darkness, respectively. Comparative analysis of gene expression was designed to correlate the effect of blue light and physiological mechanisms on the molecular level. PRINCIPAL FINDINGS: RNA-seq analysis yielded 70,497 non-redundant unigenes with an average length of 538 bp. 28,358 (40.2% functional transcripts encoding regions were identified. Annotation through Swissprot, Nr, GO, KEGG, and COG databases showed 25,924 unigenes compared well (E-value <10(-5 with known gene sequences, and 43 unigenes were putative BL photoreceptor. 10,440 unigenes were classified into Gene Ontology, and 8,476 unigenes were involved in 114 known pathways. Based on RPKM values, 11,660 (16.5% differentially expressed unigenes were detected between blue light and dark exposed treatments, including 7,808 upregulated and 3,852 downregulated unigenes, suggesting S. japonica had undergone extensive transcriptome re-orchestration during BL exposure. The BL-specific responsive genes were indentified to function in processes of circadian rhythm, flavonoid biosynthesis, photoreactivation and photomorphogenesis. SIGNIFICANCE: Transcriptome profiling of S. japonica provides clues to potential genes identification and future functional genomics study. The global survey of expression changes under blue light will enhance our understanding of molecular mechanisms underlying blue light induced responses in lower plants as well as facilitate future blue light photoreceptor identification and specific responsive pathways analysis.

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

    Directory of Open Access Journals (Sweden)

    Claudia Freitas Barbosa

    2013-10-01

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

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

    International Nuclear Information System (INIS)

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

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

    Science.gov (United States)

    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.

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

    International Nuclear Information System (INIS)

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

  8. Effects of Artificial Dawn and Morning Blue Light on Daytime Cognitive Performance, Well-being, Cortisol and Melatonin Levels.

    OpenAIRE

    Gabel, Virginie; Maire, Micheline; Reichert, Carolin F.; Chellappa, Sarah Laxhmi; Schmidt, Christina; Hommes, Vanja; Viola, Antoine U.; Cajochen, Christian

    2013-01-01

    Light exposure elicits numerous effects on human physiology and behavior, such as better cognitive performance and mood. Here we investigated the role of morning light exposure as a countermeasure for impaired cognitive performance and mood under sleep restriction (SR). Seventeen participants took part of a 48h laboratory protocol, during which three different light settings (separated by 2 wks) were administered each morning after two 6-h sleep restriction nights: a blue monochromatic LED (l...

  9. A single blue nanorod light emitting diode

    Science.gov (United States)

    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.

  10. Thermally enhanced blue light-emitting diode

    Science.gov (United States)

    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 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.

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

    Science.gov (United States)

    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

  12. Proposal of a mono-spectral imaging method for Blue Light Hazard evaluation on LED based luminaries

    International Nuclear Information System (INIS)

    IEC 62471 describes exposure limits to broad-spectrum incoherent optical radiation sources (UV, visible and IR). Its application seems particularly justified for the evaluation of White Phosphor-Coated Light-Emitting Diodes, which combine high luminance and a shortwave energy (blue)-rich spectrum, which potentially exposes the human eye to a Blue Light retinal Hazard. In theory, it is simply a question of measuring the spectral radiance of the light source inside the field of vision of the eye in movement then multiplying it with the function describing the Blue Light retinal Hazard. In practice, however, the measurement is not very repeatable in the case of inhomogeneous radiance. Protocols based on CCD imaging would probably improve the repeatability of measurements. This article deals with a first approach of a simple method for the evaluation of the Blue Light retinal Hazard by mono-spectral imaging. (authors)

  13. Blue- and red-light regulation and circadian control of gene expression of S-adenosylmethionine decarboxylase in Pharbitis nil

    International Nuclear Information System (INIS)

    The abundance of mRNA for S-adenosylmethionine decarboxylase (SAMDC) (EC 4.1.1.50) in leaves of Pharbitis nil is regulated by light. The level of this mRNA fluctuated dramatically, peaking 45 min after light exposure and then decreasing rapidly to a very low level. The half-life of the SAMDC mRNA was estimated by using actinomycin D to be approximately 30 min, which partly accounts for the rapid decline in the mRNA level after the peak of light induction is reached. The mRNA level for the SAMDC gene increased after light exposure from red, green, blue or UV light, but not after far-red light exposure. The short irradiation of red light increased the expression of the SAMDC gene and this induction was reverted by subsequent far-red light irradiation. The immediate blue light illumination after the initial red light exposure resulted in a further increase in the SAMDC mRNA level. These results indicate that both the blue light photoreceptor- and phytochrome-mediated pathways are involved in the light regulation of the SAMDC gene. The transcription of the SAMDC gene was also shown to be under circadian control. (author)

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

    Science.gov (United States)

    Calzia, Daniela; Panfoli, Isabella; Heinig, Nora; Schumann, Ulrike; Ader, Marius; Traverso, Carlo Enrico; Funk, Richard H W; Roehlecke, Cora

    2016-06-01

    Exposure to short wavelength light causes increased reactive oxygen intermediates production in the outer retina, particularly in the rod Outer Segments (OS). Consistently, the OS were shown to conduct aerobic ATP production through the ectopic expression of the electron transfer chain complexes I-IV and F1Fo-ATP synthase. These facts prompted us to verify if the oxidative phosphorylation in the OS is implied in the oxidative damage of the blue-light (BL) treated OS, in an organotypic model of mouse retina. Whole mouse eyeball cultures were treated with short wavelength BL (peak at 405 nm, output power 1 mW/cm(2)) for 6 h. Immunogold transmission electron microscopy confirmed the expression of Complex I and F1Fo-ATP synthase in the OS. In situ histochemical assays on unfixed sections showed impairment of respiratory Complexes I and II after BL exposure, both in the OS and IS, utilized as a control. Basal O2 consumption and ATP synthesis were impaired in the OS purified from blue-light irradiated eyeball cultures. Electron transfer capacity between Complex I and II as well as activity of Complexes I and II was decreased in blue-light irradiated purified OS. The severe malfunctioning of the OS aerobic respiratory capacity after 6 h BL treatment may be the consequence of a self-induced damage. BL exposure would cause an initial over-functioning of both the phototransduction and respiratory chain, with reactive oxygen species production. In a self-renewal vicious cycle, membrane and protein oxidative damage, proton leakage and uncoupling, would impair redox chains, perpetuating the damage and causing hypo-metabolism with eventual apoptosis of the rod. Data may shed new light on the rod-driven retinopathies such as Age Related Macular Degeneration, of which blue-light irradiated retina represents a model. PMID:27059514

  15. Synthesis and characterization of blue light emitting materials containing imidazole

    International Nuclear Information System (INIS)

    A series of novel imidazole derivatives as blue light emitting materials were synthesized by heck coupling reaction and characterized with respect to their chemical, luminescence and thermal properties. The results were shown that the imidazole derivatives were strongly blue fluorescent (λ = 455-487 nm) with high fluorescence quantum yields (Φf = 0.28-0.63). All of these compounds have excellent thermal properties (382-423 deg. C) due to the molecular structure introduced by imidazole heterocycles, and the imidazole derivatives (M1 and M2) can be polymerized as monomers

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

    Science.gov (United States)

    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

  17. Effects of special blue fluorescent light on hepatic mixed-function oxidase activity in the rat

    Energy Technology Data Exchange (ETDEWEB)

    Davis, D.R.; Yeary, R.A.; Randall, G.

    1981-01-01

    Phototherapy has been widely used in the treatment of neonatal hyperbilirubinemia. Recent reports, however, have indicated that fluorescent light may be toxic and mutagenic to mammalian cells. these findings suggest possible long-term side effects with the use of phototherapy. This study was undertaken to determine the effects of phototherapy on hepatic microsomal enzyme activity. The exposure of Sprague-Dawley and Gunn rats to special blue fluorescent light at an average irradiance of 1,200 microW/cm2 resulted in no significant changes in liver microsomal enzyme activity for aniline hydroxylase, p-nitroanisole-O-demethylase, ethylmorphine-N-demethylase, cytochrome c reductase or the quantity of cytochrome P-450. A significant decrease in aniline hydroxylase and p-nitroanisole-O-demethylase activity was observed when liver microsomes were exposed in vitro to special blue fluorescent light. Photoactivated bilirubin did not effect the activity of the mixed-function oxidase enzymes measured under the conditions of this study.

  18. Non-visual effects of light on melatonin, alertness and cognitive performance: can blue-enriched light keep us alert?

    Directory of Open Access Journals (Sweden)

    Sarah Laxhmi Chellappa

    Full Text Available BACKGROUND: Light exposure can cascade numerous effects on the human circadian process via the non-imaging forming system, whose spectral relevance is highest in the short-wavelength range. Here we investigated if commercially available compact fluorescent lamps with different colour temperatures can impact on alertness and cognitive performance. METHODS: Sixteen healthy young men were studied in a balanced cross-over design with light exposure of 3 different light settings (compact fluorescent lamps with light of 40 lux at 6500K and at 2500K and incandescent lamps of 40 lux at 3000K during 2 h in the evening. RESULTS: Exposure to light at 6500K induced greater melatonin suppression, together with enhanced subjective alertness, well-being and visual comfort. With respect to cognitive performance, light at 6500K led to significantly faster reaction times in tasks associated with sustained attention (Psychomotor Vigilance and GO/NOGO Task, but not in tasks associated with executive function (Paced Visual Serial Addition Task. This cognitive improvement was strongly related with attenuated salivary melatonin levels, particularly for the light condition at 6500K. CONCLUSIONS: Our findings suggest that the sensitivity of the human alerting and cognitive response to polychromatic light at levels as low as 40 lux, is blue-shifted relative to the three-cone visual photopic system. Thus, the selection of commercially available compact fluorescent lights with different colour temperatures significantly impacts on circadian physiology and cognitive performance at home and in the workplace.

  19. Evidence for dark repair of far ultraviolet light damage in the blue-green alga, Gloeocapsa alpicola

    International Nuclear Information System (INIS)

    The inactivating effect of far UV light on the unicellular blue-green alga Gloeocapsa alpicola could be totally reversed by exposure to blue light immediately after irradiation. However, if the irradiated cells were held in the dark before exposure to blue light, reversal became progressively less efficient, and almost disappeared after 60-80 h holding. Caffeine and acriflavine inhibited loss of photoreversibility, suggesting an involvement of excision functions. Chloramphenicol and rifampicin slightly increased the rate of loss of photoreversibility, indicating that inducible functions play only a minor role. Split UV dose experiments indicated that light-dependent repair remained operational during dark liquid holding. These results provide preliminary evidence for dark repair in G. alpicola. (author)

  20. Blue light emission of porous silicon subjected to RTP treatments

    Institute of Scientific and Technical Information of China (English)

    ZHAO Yi; YANG Deren; LIN Lei; QUE Duanlin

    2006-01-01

    Porous silicon samples were treated with the rapid thermal process (RTP) under different circumstances (N2, Ar, O2 and Air). Before and after treatments, the samples were checked by means of photoluminescence (PL) spectroscopy and Fourier transform infrared spectroscopy (FTIR). Four blue light emission peaks were found in the PL spectra of porous silicon samples subjected to the RTP treatments at temperatures above 400℃. The peak positions were found not to vary with the circumstances and temperatures of RTP treatments. It is considered that due to oxidation during the RTP treatments, the pole size of Si crystal in porous silicon decreased,resulting in the blue shift of light emission. Correlated with the Si crystal sizes discontinuous hypothesis and previous researchers' theory calculation, the PL peak positions did not vary with the RTP temperature and circumstances.

  1. Protecting the Melatonin Rhythm through Circadian Healthy Light Exposure

    Directory of Open Access Journals (Sweden)

    Maria Angeles Bonmati-Carrion

    2014-12-01

    Full Text Available Currently, in developed countries, nights are excessively illuminated (light at night, whereas daytime is mainly spent indoors, and thus people are exposed to much lower light intensities than under natural conditions. In spite of the positive impact of artificial light, we pay a price for the easy access to light during the night: disorganization of our circadian system or chronodisruption (CD, including perturbations in melatonin rhythm. Epidemiological studies show that CD is associated with an increased incidence of diabetes, obesity, heart disease, cognitive and affective impairment, premature aging and some types of cancer. Knowledge of retinal photoreceptors and the discovery of melanopsin in some ganglion cells demonstrate that light intensity, timing and spectrum must be considered to keep the biological clock properly entrained. Importantly, not all wavelengths of light are equally chronodisrupting. Blue light, which is particularly beneficial during the daytime, seems to be more disruptive at night, and induces the strongest melatonin inhibition. Nocturnal blue light exposure is currently increasing, due to the proliferation of energy-efficient lighting (LEDs and electronic devices. Thus, the development of lighting systems that preserve the melatonin rhythm could reduce the health risks induced by chronodisruption. This review addresses the state of the art regarding the crosstalk between light and the circadian system.

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

    Science.gov (United States)

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

    2015-11-01

    We have previously shown that blue light eliminates the black-pigmented oral bacteria Porphyromonas gingivalis, Prevotella intermedia, Prevotella nigrescens, and Prevotella melaninogenica. In the present study, the in vitro photosensitivity of the above black-pigmented microorganisms and four Fusobacteria species (Fusobacterium nucleatum ss. nucleatum, F. nucleatum ss. vincentii, F. nucleatum ss. polymorphum, Fusobacterium periodonticum) was investigated in pure cultures and human dental plaque suspensions. We also tested the hypothesis that phototargeting the above eight key periodontopathogens in plaque-derived biofilms in vitro would control growth within the dental biofilm environment. Cultures of the eight bacteria were exposed to blue light at 455 nm with power density of 80 mW/cm2 and energy fluence of 4.8 J/cm2. High-performance liquid chromatography (HPLC) analysis of bacteria was performed to demonstrate the presence and amounts of porphyrin molecules within microorganisms. Suspensions of human dental plaque bacteria were also exposed once to blue light at 455 nm with power density of 50 mW/cm2 and energy fluence of 12 J/cm2. Microbial biofilms developed from the same plaque were exposed to 455 nm blue light at 50 mW/cm2 once daily for 4 min (12 J/cm2) over a period of 3 days (4 exposures) in order to investigate the cumulative action of phototherapy on the eight photosensitive pathogens as well as on biofilm growth. Bacterial growth was evaluated using the colony-forming unit (CFU) assay. The selective phototargeting of pathogens was studied using whole genomic probes in the checkerboard DNA-DNA format. In cultures, all eight species showed significant growth reduction (p biofilms, respectively, (p biofilms. The cumulative blue light treatment suppressed biofilm growth in vitro. This may introduce a new avenue of prophylactic treatment for periodontal diseases. PMID:25759232

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

    OpenAIRE

    Schellenberger Costa, Benjamin; Jungandreas, Anne; Jakob, Torsten; Weisheit, Wolfram; Mittag, Maria; Wilhelm, Christian

    2012-01-01

    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 ...

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

    CERN Document Server

    MacKinlay, Alistair F; Whillock, M J

    1989-01-01

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

  5. Blue whale earplug reveals lifetime contaminant exposure and hormone profiles.

    Science.gov (United States)

    Trumble, Stephen J; Robinson, Eleanor M; Berman-Kowalewski, Michelle; Potter, Charles W; Usenko, Sascha

    2013-10-15

    Lifetime contaminant and hormonal profiles have been reconstructed for an individual male blue whale (Balaenoptera musculus, Linnaeus 1758) using the earplug as a natural aging matrix that is also capable of archiving and preserving lipophilic compounds. These unprecedented lifetime profiles (i.e., birth to death) were reconstructed with a 6-mo resolution for a wide range of analytes including cortisol (stress hormone), testosterone (developmental hormone), organic contaminants (e.g., pesticides and flame retardants), and mercury. Cortisol lifetime profiles revealed a doubling of cortisol levels over baseline. Testosterone profiles suggest this male blue whale reached sexual maturity at approximately 10 y of age, which corresponds well with and improves on previous estimates. Early periods of the reconstructed contaminant profiles for pesticides (such as dichlorodiphenyltrichloroethanes and chlordanes), polychlorinated biphenyls, and polybrominated diphenyl ethers demonstrate significant maternal transfer occurred at 0-12 mo. The total lifetime organic contaminant burden measured between the earplug (sum of contaminants in laminae layers) and blubber samples from the same organism were similar. Total mercury profiles revealed reduced maternal transfer and two distinct pulse events compared with organic contaminants. The use of a whale earplug to reconstruct lifetime chemical profiles will allow for a more comprehensive examination of stress, development, and contaminant exposure, as well as improve the assessment of contaminant use/emission, environmental noise, ship traffic, and climate change on these important marine sentinels. PMID:24043814

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

    OpenAIRE

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

    2014-01-01

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

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

    Science.gov (United States)

    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

  8. Blue light emitting diode internal and injection efficiency

    Directory of Open Access Journals (Sweden)

    Ilya E. Titkov

    2012-09-01

    Full Text Available A simple experimental method of light emitting diode (LED injection efficiency (IE determination was suggested. IE and internal quantum efficiency (IQE calculation is an actual and difficult problem in LED science. In this paper IE and IQE of blue LEDs were determined separately. The method is based on electroluminescence data fitting by the modified rate equation model. Efficiency droop caused by Auger recombination and poor injection were taken into account. Only one reasonable assumption was accepted during the calculations: IE tends to 1 at low current densities.

  9. Ultrafast blue light emission from SiC nanowires

    Institute of Scientific and Technical Information of China (English)

    Fuli Zhao; Hongxin Chen; Shaozhi Deng; Ningsheng Xu; Tianqing Jia; Zhizhan Xu

    2007-01-01

    Cubic silicon carbide (SiC) nanowires are synthesized in a catalyst-assisted process. The nanowires with diameter of ~ 40 nm exhibit strong blue light emission at room temperature under ultraviolet (UV) femtosecond laser excitation. The photon energy of peak emission is higher than the energy bandgap of cubic SiC which shows involvement of quantum confinement effect. The ultrafast fluorescence is deconvoluted by Monte-Carlo method. The results show two ultrafast decay processes whose lifetimes are about 26 and 567 ps respectively. The mechanisms of such ultrafast processes are discussed.

  10. A new Silicon Photomultiplier structure for blue light detection

    International Nuclear Information System (INIS)

    Silicon Photomultipliers are extremely promising devices for those applications requiring the detection of very low-intensity light (down to single photon detection). The major drawback of the existing prototypes is the poor detection efficiency, especially at short wavelengths (below 10% in the blue region). In this paper, a new structure aimed at improving this parameter at wavelengths ranging from 400-450 nm is presented. With respect to a conventional structure it allows a maximization of the breakdown initiation probability for a given bias voltage and a reduction of the dead area. The analysis is supported by TCAD simulations

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

    Science.gov (United States)

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

    2012-11-01

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

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

    Science.gov (United States)

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

    2015-07-01

    Phototherapy is standard care for treatment of neonatal hyperbilirubinemia. Our aim was to compare the effectiveness of broad-spectrum light (BSL) to that of blue light emitting diodes (LED) phototherapy for the treatment of jaundiced late preterm and term infants. Infants with gestational age from 35(+0) to 41(+6) weeks of gestation and nonhemolytic hyperbilirubinemia were randomized to treatment with BSL phototherapy or blue LED phototherapy. A total of 20 infants were included in the blue LED phototherapy group and 20 in the BSL phototherapy group. The duration of phototherapy was lower in the BSL than in the blue LED phototherapy group (15.8 ± 4.9 vs. 20.6 ± 6.0 hours; p = 0.009), and infants in the former group had a lower probability (p = 0.015) of remaining in phototherapy than infants in the latter. We concluded that BSL phototherapy is more effective than blue LED phototherapy for the treatment of hyperbilirubinemia in late preterm and term infants. Our data suggest that these results are not due to the different irradiance of the two phototherapy systems, but probably depend on their different peak light emissions. PMID:25545446

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

    Science.gov (United States)

    Senger, Horst; Hermsmeier, Dieter

    1994-01-01

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

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

    International Nuclear Information System (INIS)

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

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

    Directory of Open Access Journals (Sweden)

    Katsuura Tetsuo

    2012-09-01

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

  16. Regulation by blue light of the fluffy gene encoding a major regulator of conidiation in Neurospora crassa.

    Science.gov (United States)

    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

  17. Physiological responses to daily light exposure

    Science.gov (United States)

    Yang, Yefeng; Yu, Yonghua; Yang, Bo; Zhou, Hong; Pan, Jinming

    2016-04-01

    Long daylength artificial light exposure associates with disorders, and a potential physiological mechanism has been proposed. However, previous studies have examined no more than three artificial light treatments and limited metabolic parameters, which have been insufficient to demonstrate mechanical responses. Here, comprehensive physiological response curves were established and the physiological mechanism was strengthened. Chicks were illuminated for 12, 14, 16, 18, 20, or 22 h periods each day. A quadratic relationship between abdominal adipose weight (AAW) and light period suggested that long-term or short-term light exposure could decrease the amount of AAW. Quantitative relationships between physiological parameters and daily light period were also established in this study. The relationships between triglycerides (TG), cholesterol (TC), glucose (GLU), phosphorus (P) levels and daily light period could be described by quadratic regression models. TG levels, AAW, and BW positively correlated with each other, suggesting long-term light exposure significantly increased AAW by increasing TG thus resulting in greater BW. A positive correlation between blood triiodothyronine (T3) levels and BW suggested that daily long-term light exposure increased BW by thyroid hormone secretion. Though the molecular pathway remains unknown, these results suggest a comprehensive physiological mechanism through which light exposure affects growth.

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

    International Nuclear Information System (INIS)

    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/m2. 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.

  19. Size effect on efficiency droop of blue light emitting diode

    Energy Technology Data Exchange (ETDEWEB)

    Tao, Y.B.; Chen, Z.Z. [State Key Laboratory for Artificial Microstructures and Mesoscopic Physics, School of Physics, Peking University, Beijing 100871 (China); Institute of Photonics, University of Strathclyde, Glasgow G4 0NW (United Kingdom); Wang, S.Y.; Zhang, G.Y. [State Key Laboratory for Artificial Microstructures and Mesoscopic Physics, School of Physics, Peking University, Beijing 100871 (China); Gong, Z.; Xie, E.Y.; Chen, Y.J.; Zhang, Y.F.; McKendry, J.; Massoubre, D.; Gu, E.D. [Institute of Photonics, University of Strathclyde, Glasgow G4 0NW (United Kingdom); Rae, B.R.; Henderson, R.K. [Institute for Integrated Micro and Nano Systems, University of Edinburgh, Edinburgh EH9 3JL (United Kingdom)

    2012-03-15

    In this paper, the size effects on the efficiency droop (ED) in blue InGaN/GaN quantum well light emitting diode are investigated. The smaller size LEDs can work well under much higher power density, especially when the size is reduced to under 40 micro-meters. It shows a weaker ED in these small LEDs. Time correlated single photon counting (TCSPC) measurements show a longer electroluminescence lifetime for smaller size LEDs, which implicates the nonradiative recombination is reduced. It is likely due to Auger recombination reduction by quantum well (QW) band flattened with the device size decreasing. Cathodoluminescence results indicates that the strain in QWs is relaxed both in the whole pillar and along radial direction of the pillar. The better performance of the smaller size LED is likely attributed to strain relaxation (copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

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

    Science.gov (United States)

    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

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

    OpenAIRE

    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 search...

  2. Chronic artificial blue-enriched white light is an effective countermeasure to delayed circadian phase and neurobehavioral decrements.

    Science.gov (United States)

    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

  3. 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).

    Science.gov (United States)

    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

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

    DEFF Research Database (Denmark)

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

    Recently developed blue light emitting diodes (LEDs) for the optical stimulation of quartz for use in routine optically stimulated luminescence (OSL) dating and retrospective dosimetry have been tested. For similar power densities, it was found that the higher energy light provided by the blue LEDs...

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

    Science.gov (United States)

    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

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

    Science.gov (United States)

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

    2010-05-01

    Background: Methycillin resistant staphylococcus aureus (MRSA) bacteria continue to defy most available antibiotics. As a result infections with MRSA remain a growing public health concern. As a paradigm shift and a significant departure from the on-going trend to develop stronger drug-based therapies, we studied the effect of 405 nm and 470 nm wavelengths of blue light on two strains of MRSA—US-300 strain of CA-MRSA and the IS853 strain of HA-MRSA—in vitro. Methods: We cultured and plated each strain, following which bacteria colonies were irradiated with 0, 1, 3, 5, 7, 9, 11, 13, 15, 17, 19, 25, 30, 35, 40, 45, 50, 55, or 60 Jcm-2 energy densities—just once. Specimens were incubated at 35° C for 24 h. Then, digital images obtained were quantified to obtain colony counts and the aggregate area occupied by bacteria colonies. Results: Each wavelength produced a statistically significant dose-dependent reduction in both the number and the aggregate area of colonies formed by each bacteria strain (PMRSA 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.

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

    Science.gov (United States)

    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 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

  8. Test-retest repeatability of the pupil light response to blue and red light stimuli in normal human eyes using a novel pupillometer

    DEFF Research Database (Denmark)

    Herbst, Kristina; Sander, Birgit; Milea, Dan; Lund-Andersen, Henrik; Kawasaki, Aki

    2011-01-01

    In this study, we evaluated the repeatability of pupil responses to colored light stimuli in healthy subjects using a prototype chromatic pupillometer. One eye of 10 healthy subjects was tested twice in the same day using monochromatic light exposure at two selected wavelengths (660 and 470 nm......, we have developed a novel prototype of color pupillometer which demonstrates good repeatability in evoking and recording the pupillary response to a bright blue and red light stimulus......., intensity 300 cd/m(2)) presented continuously for 20 s. Pupil responses were recorded in real-time before, during, and after light exposure. Maximal contraction amplitude and sustained contraction amplitude were calculated. In addition, we quantified the summed pupil response during continuous light...

  9. Test-retest repeatability of the pupil light response to blue and red light stimuli in normal human eyes using a novel pupillometer

    DEFF Research Database (Denmark)

    Herbst, Kristina; Sander, Birgit; Milea, Dan; Lund-Andersen, Henrik; Kawasaki, Aki

    2011-01-01

    In this study, we evaluated the repeatability of pupil responses to colored light stimuli in healthy subjects using a prototype chromatic pupillometer. One eye of 10 healthy subjects was tested twice in the same day using monochromatic light exposure at two selected wavelengths (660 and 470¿nm......, we have developed a novel prototype of color pupillometer which demonstrates good repeatability in evoking and recording the pupillary response to a bright blue and red light stimulus......., intensity 300¿cd/m(2)) presented continuously for 20¿s. Pupil responses were recorded in real-time before, during, and after light exposure. Maximal contraction amplitude and sustained contraction amplitude were calculated. In addition, we quantified the summed pupil response during continuous light...

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

    Science.gov (United States)

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

    1998-01-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1985-02-01

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

  12. Exposure to seismic survey alters blue whale acoustic communication.

    Science.gov (United States)

    Di Iorio, Lucia; Clark, Christopher W

    2010-02-23

    The ability to perceive biologically important sounds is critical to marine mammals, and acoustic disturbance through human-generated noise can interfere with their natural functions. Sounds from seismic surveys are intense and have peak frequency bands overlapping those used by baleen whales, but evidence of interference with baleen whale acoustic communication is sparse. Here we investigated whether blue whales (Balaenoptera musculus) changed their vocal behaviour during a seismic survey that deployed a low-medium power technology (sparker). We found that blue whales called consistently more on seismic exploration days than on non-exploration days as well as during periods within a seismic survey day when the sparker was operating. This increase was observed for the discrete, audible calls that are emitted during social encounters and feeding. This response presumably represents a compensatory behaviour to the elevated ambient noise from seismic survey operations. PMID:19776059

  13. Exposure to seismic survey alters blue whale acoustic communication

    OpenAIRE

    Di Iorio, Lucia; Clark, Christopher W.

    2009-01-01

    The ability to perceive biologically important sounds is critical to marine mammals, and acoustic disturbance through human-generated noise can interfere with their natural functions. Sounds from seismic surveys are intense and have peak frequency bands overlapping those used by baleen whales, but evidence of interference with baleen whale acoustic communication is sparse. Here we investigated whether blue whales (Balaenoptera musculus) changed their vocal behaviour during a seismic survey th...

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

    Science.gov (United States)

    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.

  15. Pupillary Light Reaction during High Altitude Exposure

    OpenAIRE

    Schultheiss, Maximilian; Schommer, Kai; Schatz, Andreas; Wilhelm, Barbara; Peters, Tobias; Fischer, M. Dominik; Zrenner, Eberhart; Bartz-Schmidt, Karl U.; Gekeler, Florian; Willmann, Gabriel, 1977-

    2014-01-01

    Purpose This study aimed to quantify the pupillary light reaction during high altitude exposure using the state of the art Compact Integrated Pupillograph (CIP) and to investigate a potential correlation of altered pupil reaction with severity of acute mountain sickness (AMS). This work is related to the Tübingen High Altitude Ophthalmology (THAO) study. Methods Parameters of pupil dynamics (initial diameter, amplitude, relative amplitude, latency, constriction velocity) were quantified in 14...

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

    Science.gov (United States)

    Cope, K. R.; Bugbee, B.

    2011-12-01

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

  17. Efficient fluorescent red, green, and blue organic light-emitting devices with a blue host of spirobifluorene derivative

    Energy Technology Data Exchange (ETDEWEB)

    Lee, R.-H. [Department of Chemical and Material Engineering, National Yunlin University of Science and Technology, Yunlin 640, Taiwan (China)], E-mail: lerongho@yuntech.edu.tw; Huang, Y.-W.; Wang, Y.-Y. [Department of Chemical and Material Engineering, National Yunlin University of Science and Technology, Yunlin 640, Taiwan (China); Chang, H.-Y. [EChem Hightech CO., LTD, Hsin-Chu Industrial Park, Hu-Kou, Hsin-Chu, Taiwan (China)

    2008-06-02

    Efficient fluorescent blue, green, and red (RGB) organic light-emitting devices (OLEDs) were fabricated using a blue host material of pyrimidine-containing spirobifluorene derivative 2,7-bis[2-(4-tert-butylphenyl)pyrimidine-5-yl]-9,9'-spirobifluorene (TBPSF) doped with blue dye perylene, green dye 10-(2-benzothiazolyl)-1,1,7,7-tetramethyl-2,3,6,7-tetrahydro-1H,5H, 11H-benzo[l] pyrano[6,7,8-ij] quinolizin-11-one (C545T), and red dye 4-(dicyanomethylene)-2-t-butyl-6-(1,1,7,7-tetramethyljulolidyl-9-enyl) -4H-pyran (DCJTB), respectively. The brightness and current efficiency of the perylene doped blue device reached 10117 cd/m{sup 2} and 2.97 cd/A. Green emission of the C545T doped device reached 8500 cd/m{sup 2} and 13.0 cd/A. Red emission of the DCJTB doped device can be as high as 9000 cd/m{sup 2} and 2.0 cd/A, respectively. High color purity of the blue (Commission Internationale de L'Eclairage (CIE{sub x,y}) coordinates (CIE, x = 0.27, y = 0.24)), green (CIE, x = 0.19, y = 0.63) and red (CIE, x = 0.62, y = 0.37) emissions were achieved for RGB dyes doped TBPSF OLEDs. High brightness, large current efficiency, and good color purity of TBPSF-based RGB OLEDs were obtained by the configuration optimization device, such as inserting the hole and electron-injection materials, and suitable dopant content and light emitting layer thickness.

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

    Energy Technology Data Exchange (ETDEWEB)

    Arto V. Nurmikko; Jung Han

    2004-10-01

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

  19. A train of blue light pulses delivered through closed eyelids suppresses melatonin and phase shifts the human circadian system

    Directory of Open Access Journals (Sweden)

    Figueiro MG

    2013-10-01

    Full Text Available Mariana G Figueiro, Andrew Bierman, Mark S ReaLighting Research Center, Rensselaer Polytechnic Institute, Troy, NY, USAAbstract: A model of circadian phototransduction was published in 2005 to predict the spectral sensitivity of the human circadian system to narrow-band and polychromatic light sources by combining responses to light from the spectral-opponent “blue” versus “yellow” cone bipolar pathway with direct responses to light by the intrinsically photosensitive retinal ganglion cells. In the model, depolarizing “blue” responses, but not hyperpolarizing “yellow” responses, from the “blue” versus “yellow” pathway are combined with the intrinsically photosensitive retinal ganglion cell responses. Intrinsically photosensitive retinal ganglion cell neurons are known to be much slower to respond to light than the cone pathway, so an implication of the model is that periodic flashes of “blue” light, but not “yellow” light, would be effective for stimulating the circadian system. A within-subjects study was designed to test the implications of the model regarding retinal exposures to brief flashes of light. The study was also aimed at broadening the foundation for clinical treatment of circadian sleep disorders by delivering flashing light through closed eyelids while people were asleep. In addition to a dark control night, the eyelids of 16 subjects were exposed to three light-stimulus conditions in the phase delay portion of the phase response curve while they were asleep: (1 2-second flashes of 111 W/m2 of blue (λmax ≈ 480 nm light once every minute for 1 hour, (2 131 W/m2 of green (λmax ≈ 527 nm light, continuously on for 1 hour, and (3 2-second flashes of the same green light once every minute for 1 hour. Inferential statistics showed that the blue flash light-stimulus condition significantly delayed circadian phase and significantly suppressed nocturnal melatonin. The results of this study further our

  20. Blue news update: BODIPY-GTP binds to the blue-light receptor YtvA while GTP does not.

    Directory of Open Access Journals (Sweden)

    Matthias Dorn

    Full Text Available Light is an important environmental factor for almost all organisms. It is mainly used as an energy source but it is also a key factor for the regulation of multiple cellular functions. Light as the extracellular stimulus is thereby converted into an intracellular signal by photoreceptors that act as signal transducers. The blue-light receptor YtvA, a bacterial counterpart of plant phototropins, is involved in the stress response of Bacillus subtilis. The mechanism behind its activation, however, remains unknown. It was suggested based on fluorescence spectroscopic studies that YtvA function involves GTP binding and that this interaction is altered by absorption of light. We have investigated this interaction by several biophysical methods and show here using fluorescence spectroscopy, ITC titrations, and three NMR spectroscopic assays that while YtvA interacts with BODIPY-GTP as a fluorescent GTP analogue originally used for the detection of GTP binding, it does not bind GTP.

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

    Science.gov (United States)

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

    2001-01-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

    Arto V. Nurmikko; Jung Han

    2007-03-31

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

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

    Science.gov (United States)

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

    2015-04-01

    In the present study, the effects of red and blue LED lights on the accumulation of ascorbic acid (AsA) were investigated in the juice sacs of three citrus varieties, Satsuma mandarin, Valencia orange, and Lisbon lemon. The results showed that the blue LED light treatment effectively increased the AsA content in the juice sacs of the three citrus varieties, whereas the red LED light treatment did not. By increasing the blue LED light intensity, the juice sacs of the three citrus varieties accumulated more AsA. Moreover, continuous irradiation with blue LED light was more effective than pulsed irradiation for increasing the AsA content in the juice sacs of the three citrus varieties. Gene expression results showed that the modulation of AsA accumulation by blue LED light was highly regulated at the transcription level. The up-regulation of AsA biosynthetic genes (CitVTC1, CitVTC2, CitVTC4, and CitGLDH), AsA regeneration genes (CitMDAR1, CitMDAR2, and CitDHAR) and two GSH-producing genes (CitGR and CitchGR) contributed to these increases in the AsA content in the three citrus varieties. PMID:25711821

  4. Blue-light induced development of chloroplasts in isolated seedling roots

    International Nuclear Information System (INIS)

    Excised roots of pea seedlings (Pisum sativum var. 'Alaska') cultured in a synthetic medium under sterile conditions exhibited differentiation of functional chloroplasts from leucoplasts when irradiated with blue light (350 to 550 nm). This transition was a relatively slow process; nevertheless, the chloroplasts formed in blue light compared very well to leaf chloroplasts as far as micro-structure and photosynthetic activities are concerned. Apparently certain activities of the apical meristem are mandatory in bringing about a transition from leucoplasts to chloroplasts in blue light. After short-time labelling with [3H]uridine the synthesis of plastid ribosomal RNA (rRNA) was studied either during irradiation with blue and red light (600 to 700 nm), respectively, or in darkness. Polyacrylamide gel electrophoresis revealed that in blue light the synthesis of specific chloroplast rRNA species with molecular weights of 1.1 x 106 and 0.56 x 106 daltons was markedly stimulated. In contrast, in dark cultured roots these RNA species were synthesized to a limited extent only whereas the cytoplasmic rRNA species of 1.3 x 106 and 0.7 x 106 daltons molecular weight were preferentially formed. The same held true for roots irradiated with red light. (author)

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

    Science.gov (United States)

    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.

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

    International Nuclear Information System (INIS)

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

  7. Visible light communication using a blue GaN mu LED and fluorescent polymer color converter

    OpenAIRE

    Chun, Hyunchae; Manousiadis, Pavlos; Rajbhandari, Sujan; Vithanage, D.A.; Faulkner, G.; Tsonev, Dobroslav; Mckendry, Jonathan J.D.; Videv, Stefan; Xie, Enyuan; Gu, Erdan; Martin D. Dawson; Haas, Harald; Turnbull, Graham; Samuel, Ifor D. W.; O'Brien, Dominic

    2014-01-01

    This letter presents a novel technique to achieve high-speed visible light communication (VLC) using white light generated by a blue GaN mu LED and a yellow fluorescent copolymer. We generated white light suitable for room illumination by optimizing the ratio between the blue electroluminescence of the mu LED and yellow photoluminescence of the copolymer color converter. Taking advantage of the components' high bandwidth, we demonstrated 1.68 Gb/s at a distance of 3 cm (at 240 lx illumination...

  8. Visible-light photocatalytic degradation of methylene blue with Fe doped CdS nanoparticles

    International Nuclear Information System (INIS)

    Fe doped CdS nanoparticles (Cd1−xFexS; where x = 0.00, 0.03, 0.05 and 0.10) were synthesized by a chemical precipitation method. The synthesized products were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), Raman and UV–vis spectrometer. The XRD and TEM measurements show that the size of crystallites is in the range of 2–10 nm. With increased the Fe doping concentration, the position of the Raman bands shifted towards higher wavenumbers and their intensities decreased drastically. Optical measurements indicated that the absorption band edge shifted towards longer wavelength upon Fe doping. Direct allowed band gap of undoped and Fe doped CdS nanoparticles measured by UV–vis spectrometer were 2.3 and 2.2 eV at 100 °C, respectively. Photocatalytic activities of CdS and Fe doped CdS were evaluated by irradiating the solution of methylene blue (MB) and sample under visible light. It was found that Fe doped CdS bleaches MB much faster than undoped CdS upon its exposure to the visible light. The optimum Fe/Cd ratio was observed to be 3 mol% for photocatalytic applications. In contrast, little degradation was observed for the pure CdS powder.

  9. Photocatalytic Degradation of Methylene Blue with Side-glowing Optical Fiber Deliverying Visible Light

    Institute of Scientific and Technical Information of China (English)

    储金宇; 仲蕾

    2012-01-01

    The side-glowing optical fibers (SOFs) were chosen as the conducting medium of endogenous light; and 20 mg·L-1 methylene blue was chosen as the target to be degraded. The SOF is made up of quartz core with a silicon cladding, which can emit light through side surface more uniformly and transmit light for longer distance to avoid attenuation of light by liquid medium. The filament lamp was chosen as visible light source. Different reaction conditions, such as the presence of optical fiber or not, the quantity of SOF, light irradiation intensity were tested by measuring the methylene blue degradation of methylene blue. The results show that suitable reaction conditions were 1.167 g·L-1 Ag + /TiO 2 with 7% (by mass) of Ag + doped in TiO 2 , and 500 roots of SOF (30 cm length in solution). The photocatalytic degradation efficiency under 300W lamp irradiation for 8h was about 97%. And the photocatalytic degradation efficiency of methylene blue degradation was proportional to SOF quantity, light irradiation intensity and catalytic dosage within a certain range. Compared with general UV and visible light SOFs could save a huge amount of energy and cost, in the potential applications in dealing with organic pollutants on a large scale.

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

    Science.gov (United States)

    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.

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

    KAUST Repository

    Chi, Yu-Chieh

    2015-12-21

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

  12. Exposure of Metarhizium acridum mycelium to light induces tolerance to UV-B radiation.

    Science.gov (United States)

    Brancini, Guilherme T P; Rangel, Drauzio E N; Braga, Gilberto Ú L

    2016-03-01

    Metarhizium acridum is an entomopathogenic fungus commonly used as a bioinsecticide. The conidium is the fungal stage normally employed as field inoculum in biological control programs and must survive under field conditions such as high ultraviolet-B (UV-B) exposure. Light, which is an important stimulus for many fungi, has been shown to induce the production of M. robertsii conidia with increased stress tolerance. Here we show that a two-hour exposure to white or blue/UV-A light of fast-growing mycelium induces tolerance to subsequent UV-B irradiation. Red light, however, does not have the same effect. In addition, we established that this induction can take place with as little as 1 min of white-light exposure. This brief illumination scheme could be relevant in future studies of M. acridum photobiology and for the production of UV-B resistant mycelium used in mycelium-based formulations for biological control. PMID:26884481

  13. Antimicrobial blue light inactivation of Candida albicans: In vitro and in vivo studies.

    Science.gov (United States)

    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

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

    DEFF Research Database (Denmark)

    Ebbesen, Finn; Madsen, Poul; Støvring, Søren;

    2007-01-01

    (OSRAM L18W/860 fluorescent lamps) or blue light (Philips TL20W/52 fluorescent lamps). The concentrations of serum total bilirubin and bilirubin isomers were measured by the Vitros routine method and by HPLC, respectively. RESULTS: The decrease in serum concentrations of total bilirubin, total bilirubin...... irradiance, expressed both by serum total bilirubin, total bilirubin isomers and Z,Z-bilirubin, i.e. the turquoise spectral range is more efficient than the blue. This is in accordance with deeper penetration into the skin, lower production of the Z,E-bilirubin and greater production of E,Z-bilirubin and......AIM: To compare the efficiency of turquoise light with that of TL52 blue in treatment of preterm infants with jaundice at the same level of body irradiance. METHODS: Infants with gestational age 28-37 weeks and non-haemolytic hyperbilirubinemia were treated for 24 h with either turquoise light...

  15. Cardio-autonomic control and wellbeing due to oscillating color light exposure.

    Science.gov (United States)

    Grote, Vincent; Kelz, Christina; Goswami, Nandu; Stossier, Harald; Tafeit, Erwin; Moser, Maximilian

    2013-04-10

    We investigated the cardio-autonomic and psychological effects of colored light cycling with the wavelength of ultradian rhythms. In two consecutive experiments, an explorative, longitudinal test followed by a randomized crossover design, 20 healthy subjects each were exposed to oscillating red, green and blue light. Heart rate, heart rate variability (HRV) and subjective wellbeing were measured. Significant effects of the oscillating color light exposure were observed for heart rate and cardio-autonomic control rhythms, derived from HRV (p≤.001). These effects on HRV were replicated in the second experiment in comparison to a similar white light exposure protocol (p≤.05). Vigilance showed improvement over the two weeks (p≤.001) in the longitudinal study. External color light cycling at the wavelength of blood pressure oscillations appears to amplify the endogenous autonomic oscillations. This leads to an optimization of cardio-autonomic control; an effect that was reflected shortly after the onset of the light exposure sessions by the increase of heart rate variability. From the results, we conclude that it takes repeated light exposure session to foster the positive effects on the psychological aspects, as we observed an increase of subjectively perceived mood only in the longitudinal study, not for the crossover design study. The results of our study imply some possible health effects of a color light exposure that is adjusted to 10 s and 1 min oscillations of humans' ultradian rhythms. These novel results show possible applications of oscillating visual inputs to the activation of processes connected to physiological regulation. PMID:23506685

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

    DEFF Research Database (Denmark)

    Ebbesen, Finn; Vandborg, Pernille K; Madsen, Poul H;

    2016-01-01

    phototherapy is light emitting diodes (LEDs). AIM: Compare the bilirubin reducing effect in jaundiced neonates treated either with turquoise- or blue LED light with peak emission at 497 nm or 459 nm, respectively, with equal irradiance on the infants. METHODS: Infants with gestational age ≥33 weeks and...... uncomplicated hyperbilirubinemia were randomized to either turquoise- or blue LED light from above, and were treated for 24 h. The mean irradiance footprint at skin level was 5.2x10(15) and 5.1x10(15) photons /cm(2)/s, respectively. RESULTS: 46 infants received turquoise- and 45 blue light. The median (95% CI......) decrease of total serum bilirubin was 35.3% (32.5; 37.3) and 33.1% (27.1; 36.8) for infants treated with turquoise- and blue light, respectively. The difference was non-significant (p=0.53). The decrease was positively correlated to postnatal age and negatively to birth weight. CONCLUSION: Using LED light...

  17. Evaluation of Patient’s Exposure Rate in Handling Sensitive Films to Green and Blue Spectrum

    Directory of Open Access Journals (Sweden)

    R. Zohdi Aghdam

    2005-08-01

    Full Text Available Introduction & Background: X-photons have an im-portant role in disease diagnosis in medical examina-tion by radiography. The correct employment of ra-diation reduces patients and radiographers over-exposure; it also increases half-life of the machine. In order to use high doses especially in bulky masses, over-exposure occurs for the patient. The aim of this study is to investigate varied rates of received doses in patients by two green and blue spectrum sensitive films. Patients & Methods: To determine differences be-tween the patients received doses, data were collected from conditions in which two sensitive films to green and blue spectrum were used. These data include, KV, mass, FFD, and radiation dose. Radiation dose was determined in terms of mili-rontgen per mili-ampere per minute. Results: Obtained results showed different rates in the two sensitive films. The greatest radiation for lat-eral lumbar, lumbar thoracic, maxillary or frontal si-nuses, abdomen and pelvis were 1218.37, 750.45, 574.2, 466.6 and 466.6 respectively. The lowest radia-tions for the same regions were 620.01, 519.84, 408.04, 285.1 and 245.76 respectively. Discussion: Our results revealed that radiation dose (mR was significantly different between the two sensitive films to the green and blue spectrums. The reduction in green spectrum sensitive film was due to AgBr (I emulsions and intensifying screen. Although the condition was meant to reduce exposure, image resolution and diagnostic power were also reduced. Therefore to obtain a high resolution image, blue spectrum sensitive films are sometimes used, resulting in patients over-exposure. In general, we suggest that in order to reduce exposure and get higher resolution, these two films can be used for radiography.

  18. A novel strategy for selective gene delivery by using the inhibitory effect of blue light on jetPRIME-mediated transfection.

    Science.gov (United States)

    Dateki, Minori; Imamura, Osamu; Arai, Masaaki; Shimizu, Hidehisa; Takishima, Kunio

    2016-07-01

    Photodynamic control of gene delivery is a new technology with growing applications in gene therapy and basic cell research. Main approaches of light-selective gene delivery rely on the light-dependent enhancement of transfection efficiency. Studies focused on light-stimulated inhibitory regulation of transfection have rarely been reported. Here, we tried to establish a novel procedure of light-dependent inhibition of transfection. Our experiments, conducted with several types of commercial transfection reagents, revealed that jetPRIME-mediated transfection was strongly inhibited by blue light. Although the uptake of reagent-DNA complex was drastically reduced, preliminary exposure of cells or reagent-DNA complex to blue light had no inhibitory effect on the transfection efficiency. The inhibitory effect was wavelength-dependent and mediated by reactive oxygen species. Partial exposure of a culture vessel to blue light resulted in selective gene delivery into cells grown on the unexposed area of the vessel. By using this approach, different types of plasmid DNA were delivered into different areas in the culture vessel. This novel approach to the inhibitory control of transfection provides practical options for research and therapeutics. Biotechnol. Bioeng. 2016;113: 1560-1567. © 2015 Wiley Periodicals, Inc. PMID:26666702

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

    Science.gov (United States)

    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.

  20. Comparison and correction of the light sensor output from 48 wearable light exposure devices by using a side-by-side field calibration method

    DEFF Research Database (Denmark)

    Markvart, Jakob; Hansen, Åse Marie; Christoffersen, Jens

    2015-01-01

    . We tested 48 Actiwatch devices side by side under various light sources and present the red, green, blue, and white light response variability among the Actiwatches. The influence of different spatial and spectral light environments on the white light response when compared with the output from a...... equipment variability. To compensate for inter-equipment variability we stress the need for a field calibration procedure. When light exposure devices of lower grade quality are used in spectrally and spatially changing light environments, daylight from a diffused overcast sky is suggested to be used for...

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    Lafuente, María T; Alférez, Fernando

    2015-11-01

    Studies on the antimicrobial properties of light have considerably increased due in part to the development of resistance to actual control methods. This study investigates the potential of light-emitting diodes (LED) blue light for controlling Penicillium digitatum and Penicillium italicum. These fungi are the most devastating postharvest pathogens of citrus fruit and cause important losses due to contaminations and the development of resistant strains against fungicides. The effect of different periods and quantum fluxes, delaying light application on the growth and morphology of P. digitatum strains resistant and sensitive to fungicides, and P. italicum cultured at 20°C was examined. Results showed that blue light controls the growth of all strains and that its efficacy increases with the quantum flux. Spore germination was always avoided by exposing the cultures to high quantum flux (700 μmol m(-2) s(-1) ) for 18 h. Continuous light had an important impact on the fungus morphology and a fungicidal effect when applied at a lower quantum flux (120 μmol m(-2) s(-1) ) to a growing fungus. Sensitivity to light increased with mycelium age. Results show that blue light may be a tool for P. digitatum and P. italicum infection prevention during handling of citrus fruits. PMID:26288067

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

    Science.gov (United States)

    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.

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

    Directory of Open Access Journals (Sweden)

    Ji Hongbin

    2016-06-01

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

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

    Directory of Open Access Journals (Sweden)

    Anne-Katrin Mahlein

    2015-06-01

    Full Text Available 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.

  6. Evaluation of Patient’s Exposure Rate in Handling Sensitive Films to Green and Blue Spectrum

    OpenAIRE

    R. Zohdi Aghdam; R. Gholamnia

    2005-01-01

    Introduction & Background: X-photons have an im-portant role in disease diagnosis in medical examina-tion by radiography. The correct employment of ra-diation reduces patients and radiographers over-exposure; it also increases half-life of the machine. In order to use high doses especially in bulky masses, over-exposure occurs for the patient. The aim of this study is to investigate varied rates of received doses in patients by two green and blue spectrum sensitive films. Patients & M...

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2009-10-15

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

  8. Study on preparation and application performance of blue sky rare earth light storage and emission material

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    Under reduction atmosphere, a blue sky rare earth silicate light storage and emission material was prepared by high temperature solid phase synthesis. The best constituent ratio of this material was determined through orthogonal experiment, and its excitation and emission spectra and X-ray diffraction patterns were measured. And a comparative study was conducted on its application properties.

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

    Science.gov (United States)

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

    2015-09-01

    In the present study, the effects of blue LED light intensity on carotenoid accumulation and expression of genes related to carotenoid biosynthesis were investigated in the juice sacs of Satsuma mandarin (Citrus unshiu Marc.) and Valencia orange (Citrus sinensis Osbeck) in vitro. The results showed that 100 μmol m(-2)s(-1) blue LED light (100B) was effective for increasing carotenoid content, especially β-cryptoxanthin, in Satsuma mandarin after cultured in vitro for four weeks. In Valencia orange, in contrast, 50 μmol m(-2)s(-1) blue LED light (50B) treatment was effective for inducing carotenoid accumulation through increasing the contents of two major carotenoids, all-trans-violaxanthin and 9-cis-violaxanthin. In addition, gene expression results showed that the simultaneous increases in the expression of genes (CitPSY, CitPDS, CitZDS, CitLCYb2, and CitHYb) involved in producing β,β-xanthophylls were well consistent with the accumulation of β-cryptoxanthin in Satsuma mandarin under 100B, and violaxanthin in Valencia orange under 50B. The results presented herein contribute to further elucidating the regulatory mechanism of carotenoid accumulation by blue LED light. PMID:26432407

  10. Treatment of attention deficit hyperactivity disorder insomnia with blue wavelength light-blocking glasses

    OpenAIRE

    Fargason, Rachael

    2013-01-01

    Rachel E Fargason, Taylor Preston, Emily Hammond, Roberta May, Karen L GambleDepartment of Psychiatry and Behavioral Neurobiology, University of Alabama at Birmingham School of Medicine, Birmingham, AL, USABackground: The aim of this study was to examine a nonmedical treatment alternative to medication in attention deficit hyperactivity disorder (ADHD) insomnia, in which blue wavelength light-blocking glasses are worn during the evening hours to counteract the phase-delaying effect of light. ...

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

    OpenAIRE

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

    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 photoinduced holes, creating interfacial traps between the gate dielectric and nanowire cha...

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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

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

    Science.gov (United States)

    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.

  15. Origin and Characteristics of Blue Light Emission in Solid State Cathodoluminescence of MEH-PPV

    Institute of Scientific and Technical Information of China (English)

    QU Chong; XU Zheng; TENG Feng; QIAN Lei; YU Wen-Ge; QUAN Shan-Yu; XU Xu-Rong

    2004-01-01

    Based on our previous study [Chin. Phys. Lett. 20 (2003) 1144] on the solid-state cathodoluminescence from organic luminescent materials, here we study the origin and characteristics of blue light emission in solid-state cathodoluminescence of Poly [(2-methoxy-5-(2′-ethyl-hexyloxy)phenylene vinyene] (MEH-PPV) and the dependence of each spectral peak on electric field strength. The results demonstrate that the blue spectral shift benefits from field ionization of excitons, and three regions of electric field are found, in which there are pure exciton emission, coexistence of exciton emission and radiative recombination, and pure radiative recombination.

  16. Blue and white light electroluminescence in a multilayer OLED using a new aluminium complex

    Indian Academy of Sciences (India)

    Pabitra K Nayak; Neeraj Agarwal; Farman Ali; Meghan P Patankar; K L Narasimhan; N Periasamy

    2010-11-01

    Synthesis, structure, optical absorption, emission and electroluminescence properties of a new blue emitting Al complex, namely, bis-(2-amino-8-hydroxyquinolinato), acetylacetonato Al(III) are reported. Multilayer OLED using the Al complex showed blue emission at 465 nm, maximum brightness of ∼ 425 cd/m2 and maximum current efficiency of 0.16 cd/A. Another multilayer OLED using the Al complex doped with phosphorescent Ir complex showed `white’ light emission, CIE coordinate (0.41, 0.35), maximum brightness of ∼ 970 cd/m2 and maximum current efficiency of 0.53 cd/A.

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

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

    Directory of Open Access Journals (Sweden)

    Ying Wang

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

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

    Science.gov (United States)

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

    2016-01-01

    We investigated sleep quality and melatonin in 12 adults who wore blue-light shield or control eyewear 2 hours before sleep while using a self-luminous portable device, and assessed visual quality for the two eyewear types. Overnight melatonin secretion was significantly higher after using the blue-light shield (P visual quality. PMID:26730983

  1. Blue-Light-Independent Activity of Arabidopsis Cryptochromes in the Regulation of Steady-State Levels of Protein and mRNA Expression

    Institute of Scientific and Technical Information of China (English)

    Yue-Jun Yang; Xuan-Ming Liu; Chen-Tao Lin; Ze-Cheng Zuo; Xiao-Ying Zhao; Xu Li; John Klejnot; Yan Li; Ping Chen; Song-Ping Liang; Xu-Hong Yu

    2008-01-01

    Cryptochromes are blue-light receptors that mediate blue-light inhibition of hypocotyl elongation and bluelight stimulation of floral initiation in Arabidopsis. In addition to their blue-light-dependent functions, cryptochromes are also involved in blue-light-independent regulation of the circadian clock, cotyledon unfolding, and hypocotyl inhibition.However, the molecular mechanism associated with the blue-light-independent function of cryptochromes remains unclear. We reported here a comparative proteomics study of the light regulation of protein expression. We showed that, as expected, the protein expression of many metabolic enzymes changed in response to both blue light and red light. Surprisingly, some light-regulated protein expression changes are impaired in the cry1cry2 mutant in both blue light and red light. This result suggests that, in addition to mediating blue-light-dependent regulation of protein expression, cryptochromes are also involved in the blue-light-independent regulation of gene expression. Consistent with this hypothesis,the cry1cry2 mutant exhibited reduced changes of mRNA expression in response to not only blue light, but also red light,although the cryptochrome effects on the red-light-dependent gene expression changes are generally less pronounced.These results support a hypothesis that, in addition to their blue-light-specific functions, cryptochromes also play roles in the control of gene expression mediated by the red/far-red-light receptor phytochromes.

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

    Science.gov (United States)

    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.

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

    Directory of Open Access Journals (Sweden)

    Barbara FRĄSZCZAK

    2016-06-01

    Full Text Available The supplementation of blue light to red light enhanced plant growth compared with the use of red alone. The aim of the study was to determine the effect of different doses of blue light on the biometric traits and photosynthesis of dill plants. The plants were grown in pots in a growth chamber. They were grown in red light (100 μmol m-2 s-1 and blue light (from 10 to 50 μmol m-2 s-1 in five combinations. Light emitting diode modules were the source of light. The plants were evaluated every 7 days during vegetation, for the first time - seven days after germination and later on the 14th, 21st and 28th day after germination. The share of blue light in the spectrum significantly influenced the biometric traits of the dill plants. It significantly inhibited the elongation growth of the plants and negatively affected the increase in fresh weight. A small dose of blue light (20% had positive effect on the plants’ area. The research did not reveal a simple relationship between the amount of blue light and dry weight yield. The value of physiological indexes depended both on the combination and measurement time. The plants from the combination with 30% blue light were characterised by the greatest photosynthesis intensity. An effective share of blue light in the spectrum may range from 10 to 30% in relation to red light and depends on the plant’s development phase and on the result we want to achieve in the cultivation of plants.

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

    Science.gov (United States)

    Shi, Cuijuan; Kataoka, Hironao; Duan, Delin

    2005-09-01

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

  5. Photodynamic inactivation of Escherichia coli by methylene blue and malachite green under red LED light

    Directory of Open Access Journals (Sweden)

    Guilherme K. F. Hasegawa

    2015-04-01

    Full Text Available This study assessed the effectiveness of methylene blue (MB and malachite green (MG on photodynamic inactivation (PDI of Escherichia coli. The photosensitizers methylene blue (1000 mol L-1 and malachite green (250 mol L-1 were activated with a red light-emitting diode (LED lamp (max = 636 nm. Bacterial suspensions containing 106 CFU mL-1 were irradiated for 5, 10 and 15 minutes (energy density = 119.9 J cm-2, 223.9 J cm-2 and 335.8 J cm-2, respectively. The following experimental conditions were performed for each photosensitizer: no light irradiation or photosensitizer, irradiation only, photosensitizer only or irradiation in the presence of a photosensitizer. Next, serial dilutions were prepared and seeded onto PCA medium for the determination of the number of colony-forming units per milliliter (CFU mL-1. The results were subjected to analysis of variance (ANOVA and Tukey test (P<0.05. Photodynamic inactivation using MB and MG was effective in reducing the number of E. coli. Malachite green (250 µmol L-1 photosensitization was able to achieve reductions of over 89% in the viable counts after 15 min of irradiation and methylene blue (1000 µmol L-1, at the same conditions of irradiation, showed a rate growth inhibition of 94.6%. The red LED light used has proven to be effective in the photosensitizing dyes and proved a good alternative to conventional light sources such as laser.

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

    Science.gov (United States)

    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

  7. A fluence response study of lethality and mutagenicity of white, black, and blue fluorescent light, sunlamp, and sunlight irradiation in Chinese hamster ovary cells

    International Nuclear Information System (INIS)

    Under a set of defined experimental conditions, the fluence response of Chinese hamster ovary (CHO) cells to various light sources was studied by measuring single-cell survival and mutation to 6-thioguanine (TG) resistance. Fluorescent white, black, and blue lights were slightly lethal and mutagenic. Sunlamp light was highly lethal and mutagenic, exhibiting these biological effects within 15 sec of exposure under conditions recommended by the manufacturer for human use. Lethal and mutagenic effects were observed after 5 min of sunlight exposure; responses varied with hourly and daily variations in solar radiation. Sunlight induced TG-resistant variants possessed <5% of parental cellular hypoxanthine-guanine phosphoribosyl transferase (HGPRT) enzyme activity, suggesting that the mutation induction occurs at this locus. The cell survival and mutation-induction curves generated by exposure of cells to both sunlamp and sunlight were similar to those obtained by the use of a standard far-UV lamp

  8. Bending of Light Near a Star and Gravitational Red/Blue Shift Alternative Explanation Based on Refraction of Light

    CERN Document Server

    Gupta, D R C

    2004-01-01

    Many of the general-relativity-tests such as bending of light near a star and gravitational red/blue shift are explained without general-relativity and without Newtonian-approach. The author first casts doubts on both, the Newtonian and the relativistic approach; and proposes a novel alternative-explanation. The new alternative-explanation is based on refraction-phenomenon of optics. It predicts that as the ray passes through/near the stars atmospheric-medium, it bends due to refraction-phenomenon towards star-core, like a ray bends while passing through a prism or water-drop. A semi-empirical estimation of the atmospheric-height and its refractive-index are made to find the refraction-results. The refraction-based theory also suggests new explanation for gravitational red/blue shift; it tells that frequency remains constant (as it is so in refraction-phenomenon) and the red/blue shift is due to change in wavelength due to change in velocity of light in the medium . Estimated results for bending of light and ...

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

    Science.gov (United States)

    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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-07-31

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

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

    International Nuclear Information System (INIS)

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

  12. Photodynamics of blue-light-regulated phosphodiesterase BlrP1 protein from Klebsiella pneumoniae and its photoreceptor BLUF domain

    International Nuclear Information System (INIS)

    The BlrP1 protein from the enteric bacterium Klebsiella pneumoniae consists of a BLUF and an EAL domain and may activate c-di-GMP phosphodiesterase by blue-light. The full-length protein, BlrP1, and its BLUF domain, BlrP1BLUF, are characterized by optical absorption and emission spectroscopy. The cofactor FAD in its oxidized redox state (FADox) is brought from the dark-adapted receptor state to the 10-nm red-shifted putative signalling state by violet light exposure. The recovery to the receptor state occurs with a time constant of about 1 min. The quantum yield of signalling state formation is about 0.17 for BlrP1BLUF and about 0.08 for BlrP1. The fluorescence efficiency of the FADox cofactor is small due to photo-induced reductive electron transfer. Prolonged light exposure converts FADox in the signalling state to the fully reduced hydroquinone form FADredH- and causes low-efficient chromophore release with subsequent photo-degradation. The photo-cycle and photo-reduction dynamics in the receptor state and in the signalling state are discussed

  13. Photodynamics of blue-light-regulated phosphodiesterase BlrP1 protein from Klebsiella pneumoniae and its photoreceptor BLUF domain

    Energy Technology Data Exchange (ETDEWEB)

    Tyagi, A. [Institut II - Experimentelle und Angewandte Physik, Universitaet Regensburg, Universitaetstrasse 31, D-93053 Regensburg (Germany); Penzkofer, A. [Institut II - Experimentelle und Angewandte Physik, Universitaet Regensburg, Universitaetstrasse 31, D-93053 Regensburg (Germany)], E-mail: alfons.penzkofer@physik.uni-regensburg.de; Griese, J.; Schlichting, I. [Max-Planck-Institut fuer medizinische Forschung, Abteilung Biomolekulare Mechanismen, Jahnstrasse 29, D-69120 Heidelberg (Germany); Kirienko, Natalia V.; Gomelsky, Mark [Department of Molecular Biology, University of Wyoming, Laramie, Wyoming 82071 (United States)

    2008-12-10

    The BlrP1 protein from the enteric bacterium Klebsiella pneumoniae consists of a BLUF and an EAL domain and may activate c-di-GMP phosphodiesterase by blue-light. The full-length protein, BlrP1, and its BLUF domain, BlrP1{sub B}LUF, are characterized by optical absorption and emission spectroscopy. The cofactor FAD in its oxidized redox state (FAD{sub ox}) is brought from the dark-adapted receptor state to the 10-nm red-shifted putative signalling state by violet light exposure. The recovery to the receptor state occurs with a time constant of about 1 min. The quantum yield of signalling state formation is about 0.17 for BlrP1{sub B}LUF and about 0.08 for BlrP1. The fluorescence efficiency of the FAD{sub ox} cofactor is small due to photo-induced reductive electron transfer. Prolonged light exposure converts FAD{sub ox} in the signalling state to the fully reduced hydroquinone form FAD{sub red}H{sup -} and causes low-efficient chromophore release with subsequent photo-degradation. The photo-cycle and photo-reduction dynamics in the receptor state and in the signalling state are discussed.

  14. Photodynamics of blue-light-regulated phosphodiesterase BlrP1 protein from Klebsiella pneumoniae and its photoreceptor BLUF domain

    Science.gov (United States)

    Tyagi, A.; Penzkofer, A.; Griese, J.; Schlichting, I.; Kirienko, Natalia V.; Gomelsky, Mark

    2008-12-01

    The BlrP1 protein from the enteric bacterium Klebsiella pneumoniae consists of a BLUF and an EAL domain and may activate c-di-GMP phosphodiesterase by blue-light. The full-length protein, BlrP1, and its BLUF domain, BlrP1_BLUF, are characterized by optical absorption and emission spectroscopy. The cofactor FAD in its oxidized redox state (FAD ox) is brought from the dark-adapted receptor state to the 10-nm red-shifted putative signalling state by violet light exposure. The recovery to the receptor state occurs with a time constant of about 1 min. The quantum yield of signalling state formation is about 0.17 for BlrP1_BLUF and about 0.08 for BlrP1. The fluorescence efficiency of the FAD ox cofactor is small due to photo-induced reductive electron transfer. Prolonged light exposure converts FAD ox in the signalling state to the fully reduced hydroquinone form FAD redH - and causes low-efficient chromophore release with subsequent photo-degradation. The photo-cycle and photo-reduction dynamics in the receptor state and in the signalling state are discussed.

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

    Directory of Open Access Journals (Sweden)

    Fangqun OuYang

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

  16. Prey-mediated behavioral responses of feeding blue whales in controlled sound exposure experiments.

    Science.gov (United States)

    Friedlaender, A S; Hazen, E L; Goldbogen, J A; Stimpert, A K; Calambokidis, J; Southall, B L

    2016-06-01

    Behavioral response studies provide significant insights into the nature, magnitude, and consequences of changes in animal behavior in response to some external stimulus. Controlled exposure experiments (CEEs) to study behavioral response have faced challenges in quantifying the importance of and interaction among individual variability, exposure conditions, and environmental covariates. To investigate these complex parameters relative to blue whale behavior and how it may change as a function of certain sounds, we deployed multi-sensor acoustic tags and conducted CEEs using simulated mid-frequency active sonar (MFAS) and pseudo-random noise (PRN) stimuli, while collecting synoptic, quantitative prey measures. In contrast to previous approaches that lacked such prey data, our integrated approach explained substantially more variance in blue whale dive behavioral responses to mid-frequency sounds (r2 = 0.725 vs. 0.14 previously). Results demonstrate that deep-feeding whales respond more clearly and strongly to CEEs than those in other behavioral states, but this was only evident with the increased explanatory power provided by incorporating prey density and distribution as contextual covariates. Including contextual variables increases the ability to characterize behavioral variability and empirically strengthens previous findings that deep-feeding blue whales respond significantly to mid-frequency sound exposure. However, our results are only based on a single behavioral state with a limited sample size, and this analytical framework should be applied broadly across behavioral states. The increased capability to describe and account for individual response variability by including environmental variables, such as prey, that drive foraging behavior underscores the importance of integrating these and other relevant contextual parameters in experimental designs. Our results suggest the need to measure and account for the ecological dynamics of predator

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

    Directory of Open Access Journals (Sweden)

    Adrián Golic

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

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

    Science.gov (United States)

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

    2016-07-01

    Pseudomonas aeruginosa is among the most common pathogens that cause nosocomial infections and is responsible for about 10% of all hospital-acquired infections. In the present study, we investigated the potential development of tolerance of P. aeruginosa to antimicrobial blue light by carrying 10 successive cycles of sublethal blue light inactivation. The high-performance liquid chromatographic (HPLC) analysis was performed to identify endogenous porphyrins in P. aeruginosa cells. In addition, we tested the effectiveness of antimicrobial blue light in a mouse model of nonlethal skin abrasion infection by using a bioluminescent strain of P. aeruginosa. The results demonstrated that no tolerance was developed to antimicrobial blue light in P. aeruginosa after 10 cycles of sub-lethal inactivation. HPLC analysis showed that P. aeruginosa is capable of producing endogenous porphyrins in particularly, coproporphyrin III, which are assumed to be responsible for the photodynamic effects of blue light alone. P. aeruginosa infection was eradicated by antimicrobial blue light alone (48 J/cm(2) ) without any added photosensitizer molecules in the mouse model. In conclusion, endogenous photosensitization using blue light should gain considerable attention as an effective and safe alternative antimicrobial therapy for skin infections. Lasers Surg. Med. 48:562-568, 2016. © 2016 Wiley Periodicals, Inc. PMID:26891084

  19. Transient Response of Cadmium Telluride Modules to Light Exposure: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Deline, C.; del Cueto, J.; Albin, D. S.; Petersen, C.; Tyler, L.; TamizhMani, G.

    2011-07-01

    Commercial cadmium telluride (CdTe) photovoltaic (PV) modules from three different manufacturers were monitored for performance changes during indoor and outdoor light-exposure. Short-term transients in Voc were recorded on some modules, with characteristic times of ~1.1 hours. Outdoor performance data shows a similar drop in Voc after early morning light exposure. Preliminary analysis of FF changes show light-induced changes on multiple time scales, including a long time scale.

  20. Limits to depletion of blue-green light stimulated luminescence in feldspars: Implications for quartz dating

    DEFF Research Database (Denmark)

    Jain, M.; Singhvi, A.K.

    2001-01-01

    populations participate in the feldspar BGSL process. These are: (1) Type (A) trap populations that can be stimulated by both the infra-red and the blue-green light at 125 degreesC and, (2) Type (B) trap populations that respond only to blue-green-light stimulation at 125 degreesC. However, infra......-red stimulation at elevated temperature (220 degreesC) (ETIR) permits depletions of charges in Type (A) and Type (B) to the extent that the feldspar BGSL can be reduced by up to 97% in 5 min. These results offer prospects for (1) improved precision in paleodose estimates based on quartz; (2) BGSL dating of quartz...

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

    Science.gov (United States)

    Groves, Ethan; Palenik, Christopher S

    2016-03-01

    This study discusses the results of an evaluation of a one-part blue light-curing acrylic resin for embedding trace evidence prior to the preparation of thin sections with a microtome. Through a comparison to several epoxy resins, the physical properties relevant to both trace evidence examination and analytical microscopy in general, including as viscosity, clarity, color, hardness, and cure speed, were explored. Finally, thin sections from paint samples embedded in this acrylic resin were evaluated to determine if, through smearing or impregnation, the resin contributed to the infrared spectra. The results of this study show that blue light-curing acrylic resins provide the desired properties of an embedding medium, generate high-quality thin sections, and can significantly simplify the preparation of paint chips, fibers and a multitude of other types of microscopic samples in the forensic trace evidence laboratory. PMID:27404623

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

    Science.gov (United States)

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

    2013-01-01

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

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

    Czech Academy of Sciences Publication Activity Database

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

    2013-01-01

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

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

    Science.gov (United States)

    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.

  5. Light perception in two strictly subterranean rodents: life in the dark or blue?

    Directory of Open Access Journals (Sweden)

    Ondrej Kott

    Full Text Available 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.

  6. Enhanced visible light photocatalytic degradation of methylene blue by F-doped TiO2

    International Nuclear Information System (INIS)

    Graphical abstract: F-doped TiO2 is synthesized using a modified sol–gel method for visible photocatalytic degradation of MB with a high degradation rate of 91%. - Highlights: • F-doped TiO2 are synthesized using a modified sol–gel method. • The photocatalytic degradation of methylene blue by F-doped TiO2 is investigated. • A high methylene blue degradation rate of 91% is achieved under visible light irradiation. - Abstract: F-doped TiO2 (F-TiO2) were successfully synthesized using a modified sol–gel method. The morphologies, structures, and photocatalytic performance in the degradation of methylene blue (MB) were characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, UV–vis absorption spectroscopy, and electrochemical impedance spectra, respectively. The results show that F-TiO2 exhibits an enhanced photocatalytic performance in the degradation of MB with a maximum degradation rate of 91% under visible light irradiation as compared with pure TiO2 (32%). The excellent photocatalytic activity is due to the contribution from the increased visible light absorption, promoted separation of photo-generated electrons and holes as well as enhanced photocatalytic oxidizing species with the doping of F in TiO2

  7. Blue emitting KSCN:xCe phosphor for solid state lighting

    International Nuclear Information System (INIS)

    The intense blue emitting phosphor KSCN:xCe (x=0.005, 0.01, 0.02, 0.04) is synthesized by a simple, time saving, economical method of re-crystallization through aqueous solution at 353 K. Photoluminescence measurements showed that the said phosphor exhibits emission with good intensity peaking at 450 nm corresponding to d→f transitions of Ce3+ ion. The excitation spectra monitored at 450 nm shows small peak at 282 nm and broad intense excitation band peaking at 350 nm. The latter lies in near ultraviolet (350–410 nm) emission of UV LED. The phosphor KSCN:0.02Ce3+ shows CIE 1931 color coordinates as (0.1484, 0.0602) whereas the commercial blue phosphor BAM:Eu2+ shows the color co-ordinates as (0.1417, 0.1072), respectively, indicating better color purity for KSCN: 0.02Ce3+ compared to the BAM:Eu2+ phosphor. The color coordinates of KSCN: 0.02Ce3+ phosphor (0.1484, 0.0602) are nearer to the color coordinate for blue color suggested by the color systems EBUPAL/SECAM, sRGB Blue as well as Adobe blue(0.15, 0.06). -- Highlights: • Novel phosphor KSCN:xCe prepared for the first time. • Method is simple, time saving, economical, easy to handle. • Intense, blue, Characteristic Ce3+ emission at 450 nm. • nUV excitation, suitable for solid state lighting

  8. Effect of occupational exposure to cobalt blue dyes on the thyroid volume and function of female plate painters

    DEFF Research Database (Denmark)

    Prescott, E; Netterstrøm, B; Faber, J;

    1992-01-01

    It has previously been shown that long-term oral exposure to cobalt can cause goiter and myxedema. The effect of industrial cobalt exposure on thyroid volume and function was determined for 61 female plate painters exposed to cobalt blue dyes in two Danish porcelain factories and 48 unexposed...

  9. Development of OSL system using two high-density blue LEDs equipped with liquid light guides

    Energy Technology Data Exchange (ETDEWEB)

    Choi, J.H. [Division of Earth and Environmental Sciences, Korea Basic Science Institute, Chungbuk 363-883 (Korea, Republic of); Kim, M.J. [Center for Applied Radiation Research, Neosiskorea Co., Ltd., Daejeon 305-380 (Korea, Republic of); Cheong, C.S. [Division of Earth and Environmental Sciences, Korea Basic Science Institute, Chungbuk 363-883 (Korea, Republic of); Hong, D.G., E-mail: dghong@kangwon.ac.kr [Department of Physics, Kangwon National University, Chunchon 200-701 (Korea, Republic of)

    2014-03-15

    In recent years, considerable developments in optically stimulated luminescence (OSL) have been made in the fields of radiation dosimetry, age determination, and medical applications. A compact and economical OSL system comprising a precision x-y-z stage for loading 12 samples, a small X-ray generator for radiation dosing, and two powerful blue light emitting diodes (LEDs) for optical stimulation equipped with VIS liquid light guides (VIS-LLGs) has been developed. This paper describes the principal features of the system along with the examples of measurements performed by the system.

  10. A Flexible Blue Light-Emitting Diode Based on ZnO Nanowire/Polyaniline Heterojunctions

    OpenAIRE

    Liu, Y Y; Wang, X. Y.; Cao, Y; X. D. Chen; Xie, S. F.; X. J. ZHENG; Zeng, H. D.

    2013-01-01

    An organic/inorganic light-emitting diode (LED) consisting of n-type vertically aligned ZnO nanowires (NWs) and p-type proton acid doped polyaniline (PANi) is reported. The device was fabricated on flexible indium-tin-oxide (ITO) coated polyethylene terephthalate (PET) substrate. A broad blue light emission band ranging from 390 nm to 450 nm was observed in the electroluminescence (EL) spectra of the device, which was related to the interface recombination of electrons in the conduction band ...

  11. Genic and Allelic Interactions in the Carotenogenic Response of Myxococcus Xanthus to Blue Light

    OpenAIRE

    Martinez-Laborda, A.; Murillo, F.j.

    1989-01-01

    In the bacterium Myxococcus xanthus, the synthesis of carotenoids requires illumination with blue light. This stimulates transcription of the carB locus, which is positively required for carotenogenesis. Mutations at the carR locus and the only mutation known at carA cause constitutive expression of carB and thus remove the light requirement for carotenoid accumulation (Car(c) phenotype). The carR locus is unlinked, and carA is linked, to carB. We have now identified a novel class of car muta...

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

    Science.gov (United States)

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

    2016-08-01

    Stomata open in response to a beam of weak blue light under strong red light illumination. A blue light signal is perceived by phototropins and transmitted to the plasma membrane H(+)-ATPase that drives stomatal opening. To identify the components in this pathway, we screened for mutants impaired in blue light-dependent stomatal opening. We analyzed one such mutant, provisionally named blus2 (blue light signaling2), and found that stomatal opening in leaves was impaired by 65%, although the magnitude of red light-induced opening was not affected. Blue light-dependent stomatal opening in the epidermis and H(+) pumping in guard cell protoplasts were inhibited by 70% in blus2 Whole-genome resequencing identified a mutation in the AHA1 gene of the mutant at Gly-602. T-DNA insertion mutants of AHA1 exhibited a similar phenotype to blus2; this phenotype was complemented by the AHA1 gene. We renamed blus2 as aha1-10 T-DNA insertion mutants of AHA2 and AHA5 did not show any impairment in stomatal response, although the transcript levels of AHA2 and AHA5 were higher than those of AHA1 in wild-type guard cells. Stomata in ost2, a constitutively active AHA1 mutant, did not respond to blue light. A decreased amount of H(+)-ATPase in aha1-10 accounted for the reduced stomatal blue light responses and the decrease was likely caused by proteolysis of misfolded AHA1. From these results, we conclude that AHA1 plays a major role in blue light-dependent stomatal opening in Arabidopsis and that the mutation made the AHA1 protein unstable in guard cells. PMID:27261063

  13. Functional and Physical Interaction of Blue- and Red-Light Sensors in Aspergillus nidulans

    International Nuclear Information System (INIS)

    Light sensing is very important for organisms in all biological kingdoms to adapt to changing environmental conditions. It was discovered recently that plant-like phytochrome is in- volved in light sensing in the filamentous fungus Aspergillus nidulans [1]. Here, we show that phytochrome (FphA) is part of a protein complex containing LreA (WC-1) and LreB (WC-[2, 3], two central components of the Neurospora crassa blue-light-sensing system. We found that FphA represses sexual development and mycotoxin formation, whereas LreA and LreB stimulate both. Surprisingly, FphA interacted with LreB and with VeA, another regulator involved in light sensing and mycotoxin biosynthesis. LreB also interacted with LreA. All protein interactions occurred in the nucleus, despite cytoplasmic subfractions of the proteins. Whereas the FphA-VeA interaction was dependent on the presence of the linear tetrapyrrole in FphA, the interaction between FphA and LreB was chromophore independent. These results suggest that morphological and physiological differen- tiations in A. nidulans are mediated through a network consisting of FphA, LreA, LreB, and VeA acting in a large protein complex in the nucleus, sensing red and blue light. (author)

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

    International Nuclear Information System (INIS)

    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. (paper)

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

    DEFF Research Database (Denmark)

    Kessel, Line; Siganos, Galatios; Jørgensen, Torben;

    2011-01-01

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

  16. Do Wild Great Tits Avoid Exposure to Light at Night?

    Directory of Open Access Journals (Sweden)

    Maaike de Jong

    Full Text Available Studies of wild populations have provided important insights into the effects of artificial light at night on organisms, populations and ecosystems. However, in most studies the exact amount of light at night individuals are exposed to remains unknown. Individuals can potentially control their nighttime light exposure by seeking dark spots within illuminated areas. This uncertainty makes it difficult to attribute effects to a direct effect of light at night, or to indirect effects, e.g., via an effect of light at night on food availability. In this study, we aim to quantify the nocturnal light exposure of wild birds in a previously dark forest-edge habitat, experimentally illuminated with three different colors of street lighting, in comparison to a dark control. During two consecutive breeding seasons, we deployed male great tits (Parus major with a light logger measuring light intensity every five minutes over a 24h period. We found that three males from pairs breeding in brightly illuminated nest boxes close to green and red lamp posts, were not exposed to more artificial light at night than males from pairs breeding further away. This suggests, based on our limited sample size, that these males could have been avoiding light at night by choosing a roosting place with a reduced light intensity. Therefore, effects of light at night previously reported for this species in our experimental set-up might be indirect. In contrast to urban areas where light is omnipresent, bird species in non-urban areas may evade exposure to nocturnal artificial light, thereby avoiding direct consequences of light at night.

  17. Do Wild Great Tits Avoid Exposure to Light at Night?

    Science.gov (United States)

    de Jong, Maaike; Ouyang, Jenny Q.; van Grunsven, Roy H. A.; Visser, Marcel E.; Spoelstra, Kamiel

    2016-01-01

    Studies of wild populations have provided important insights into the effects of artificial light at night on organisms, populations and ecosystems. However, in most studies the exact amount of light at night individuals are exposed to remains unknown. Individuals can potentially control their nighttime light exposure by seeking dark spots within illuminated areas. This uncertainty makes it difficult to attribute effects to a direct effect of light at night, or to indirect effects, e.g., via an effect of light at night on food availability. In this study, we aim to quantify the nocturnal light exposure of wild birds in a previously dark forest-edge habitat, experimentally illuminated with three different colors of street lighting, in comparison to a dark control. During two consecutive breeding seasons, we deployed male great tits (Parus major) with a light logger measuring light intensity every five minutes over a 24h period. We found that three males from pairs breeding in brightly illuminated nest boxes close to green and red lamp posts, were not exposed to more artificial light at night than males from pairs breeding further away. This suggests, based on our limited sample size, that these males could have been avoiding light at night by choosing a roosting place with a reduced light intensity. Therefore, effects of light at night previously reported for this species in our experimental set-up might be indirect. In contrast to urban areas where light is omnipresent, bird species in non-urban areas may evade exposure to nocturnal artificial light, thereby avoiding direct consequences of light at night. PMID:27355354

  18. Treatment of attention deficit hyperactivity disorder insomnia with blue wavelength light-blocking glasses

    Directory of Open Access Journals (Sweden)

    Fargason RE

    2013-01-01

    Full Text Available Rachel E Fargason, Taylor Preston, Emily Hammond, Roberta May, Karen L GambleDepartment of Psychiatry and Behavioral Neurobiology, University of Alabama at Birmingham School of Medicine, Birmingham, AL, USABackground: The aim of this study was to examine a nonmedical treatment alternative to medication in attention deficit hyperactivity disorder (ADHD insomnia, in which blue wavelength light-blocking glasses are worn during the evening hours to counteract the phase-delaying effect of light. Outcome measures included sleep quality and midsleep time. The capacity of ADHD subjects to comply with treatment using the glasses was assessed.Methods: Daily bedtime, wake-up time, and compliance diaries were used to assess sleep quality and timing during a baseline observation week and a 2-week intervention period. The Pittsburgh Sleep Quality Index (PSQI was administered following baseline and intervention. The intervention protocol consisted of use of blue wavelength-blocking glasses and a moderate lighting environment during evening hours.Results: Partial and variable compliance were noted, with only 14 of 22 subjects completing the study due to nonadherence with wearing the glasses and diary completion. Despite the minimum 3-hour recommendation, glasses were worn, on average, for 2.4 hours daily. Lighting was reduced for only 58.7% of the evening. Compared with baseline, the intervention resulted in significant improvement in global PSQI scores, PSQI subcomponent scores, and sleep diary measures of morning refreshment after sleep (P = 0.037 and night-time awakenings (P = 0.015. Global PSQI scores fell from 11.15 to 4.54, dropping below the cut-off score of 5 for clinical insomnia. The more phase-delayed subjects, ie, those with an initial midsleep time after 4:15 am, trended towards an earlier midsleep time by 43.2 minutes following the intervention (P = 0.073. Participants reported less anxiety following the intervention (P = 0.048.Conclusions

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

    Science.gov (United States)

    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 migration speed, and is associated with increased reactive oxygen species generation in a dose-dependent manner without altering viability. LED-BL has the potential to contribute to the treatment of keloids and other fibrotic skin diseases and is worthy of further translational and clinical

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

    Directory of Open Access Journals (Sweden)

    Sumi Lee

    2013-01-01

    Full Text Available 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.

  1. The Acclimation of Phaeodactylum tricornutum to Blue and Red Light Does Not Influence the Photosynthetic Light Reaction but Strongly Disturbs the Carbon Allocation Pattern

    OpenAIRE

    Jungandreas, Anne; Schellenberger Costa, Benjamin; Jakob, Torsten; von Bergen, Martin; Baumann, Sven; Wilhelm, Christian

    2014-01-01

    Diatoms are major contributors to the aquatic primary productivity and show an efficient acclimation ability to changing light intensities. Here, we investigated the acclimation of Phaeodactylum tricornutum to different light quality with respect to growth rate, photosynthesis rate, macromolecular composition and the metabolic profile by shifting the light quality from red light (RL) to blue light (BL) and vice versa. Our results show that cultures pre-acclimated to BL and RL exhibited simila...

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

    OpenAIRE

    Rivas, Miguel; Rojas, Elisa; ARAYA, MARÍA C.; CALAF, GLORIA M.

    2015-01-01

    The danger of overexposure to solar ultraviolet radiation has been widely reviewed since the 1980s due to the depletion of the ozone layer. However, the benefits of mild exposure of the skin to ultraviolet (UV) light have not been widely investigated. Numerous reports have demonstrated that an association exists between low light exposure to the sun, non-melanoma skin cancer and a lack of vitamin D synthesis. As vitamin D synthesis in the body depends on skin exposure to UVB radiation from th...

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

    Science.gov (United States)

    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. Female Sprague Dawley Rats Show Impaired Spatial Memory in the 8-Arm Radial Maze under Dim Blue and Red Light

    Directory of Open Access Journals (Sweden)

    Michael Pirchl

    2010-01-01

    Full Text Available Light intensity and wavelength strongly influence mood and cognition in humans and rodent animal models. The aim of the present study was to explore if dim white (7.6–17.7 lux , blue (1.3–2.3 lux, and red light (0.8–1.4 lux affect spatial memory of male and female Sprague Dawley rats in the 8-arm radial maze. Our data show that spatial memory significantly improved within 5 daily learning sessions (each 5 trials under dim white light, which was not different between male and female rats. However, dim blue and red light significantly reduced spatial learning of female rats in the 8-arm radial maze in the last training session (session 5. In conclusion, we suggest that female Sprague Dawley rats show reduced learning under blue and red light.

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

    Science.gov (United States)

    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.

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

    Energy Technology Data Exchange (ETDEWEB)

    Xin, Yunzi; Nishio, Kazuyuki [Department of Chemistry, Graduate School of Science, Hiroshima University, Higashi-hiroshima 739-8526 (Japan); Saitow, Ken-ichi, E-mail: saitow@hiroshima-u.ac.jp [Department of Chemistry, Graduate School of Science, Hiroshima University, Higashi-hiroshima 739-8526 (Japan); Natural Science Center for Basic Research and Development (N-BARD), Hiroshima University, Higashi-hiroshima 739-8526 (Japan)

    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.

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

    Directory of Open Access Journals (Sweden)

    G. Ledru

    2014-10-01

    Full Text Available A white light source using direct phosphor-conversion excited by a blue laser diode is presented. In this preliminary study we have investigated the influence of phosphor’s thickness and operating current of the laser diode over the (x, y chromaticity coordinates, Correlated Color Temperature (CCT and Color Rendering Index (CRI. The best values found were 4000 K and 94. A 40 lm/W luminous efficacy was achieved together with a CRI close to 90 for an operating current of 0.8 A. Those values, to the best of our knowledge, were not previously reported in the literature.

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

    Science.gov (United States)

    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.

  9. Deep-blue supercontinuum light sources based on tapered photonic crystal bres

    DEFF Research Database (Denmark)

    Sørensen, Simon Toft

    The nonlinear pulse broadening phenomenon of supercontinuum generation in optical fibres is appreciated as one of the most striking in nonlinear physics. Thanks to the unique combination of high brightness and octavespanning spectra, modern “white-light” supercontinuum lasers have found numerous...... varying air hole structures. Here we demonstrate supercontinuum generation into the commercially attractive deep-blue spectral region below 400 nm from an Yb laser in such fibres. In particular, we introduce the concept of a group acceleration mismatch that allows us to enhance the amount of light in the...

  10. Hybrid TiO2-C composites for the photodegradation of methylene blue under visible light

    Directory of Open Access Journals (Sweden)

    J. Matos

    2013-01-01

    Full Text Available Photodegradation of methylene blue (MB on TiO2 in presence of activated carbons (AC was studied. Two different lamps were employed and results were compared against those obtained on a commercial TiO2. Apparent first order rate constant for the degradation of MB was higher in presence of any AC in comparison of TiO2 alone but much higher under visible light irradiation. It can be concluded that TiO2 enhances its photoactivity by a factor up to 8.7 in the degradation of MB in presence of AC and this increase was associated with the surface properties of AC.

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

  13. Effects of blue light irradiation on dental enamel remineralization in vitro

    International Nuclear Information System (INIS)

    This study aimed to investigate the effects of blue radiation on dental enamel remineralization. In addition, a methodology of analysis was developed to evaluate alterations of enamel mineral content by optical coherence tomography. Artificial lesions were formed in bovine dental enamel slabs by immersing the samples in under saturated acetate buffer (2 mL/mm2 e 6.25 mL/mm2). The lesions were irradiated with blue LED (l=455±20nm), with radiant power of 110 mW, irradiance of 1.4 W/cm2, radiant exposure of 13.8 J/cm2 and exposure time of 10 s. Remineralization was induced by pH-cycling model during 8 days. Cross-sectional hardness and optical coherence tomography (OCT) were used to assess mineral changes after remineralization. Hardness data showed that non-irradiated enamel lesions presented higher mineral content than irradiated ones and this difference was more evident in lesions formed in higher solution volume. The analysis of OCT signal also demonstrated that the mineral content of non-irradiated group was higher than in irradiated one; however, no significant difference was observed. Furthermore, significant differences in OCT sign were detected between sound and demineralized enamel. Based on the results obtained in the present study it can be concluded that blue radiation caused an inhibition of enamel remineralization. The methodology adopted for OCT analysis allowed the quantification of enamel mineral loss; however, the remineralization process could not be evaluated by this technique. (author)

  14. Photoluminescence studies of organic phosphor coated diffusing surface using blue inorganic light-emitting diode as excitation source

    International Nuclear Information System (INIS)

    We report the studies on photoluminescence (PL) of organic phosphor coated on a diffusing surface using a blue inorganic light-emitting diode (LED) array as an excitation source. The organic phosphor composite coated diffuser was used to scatter the directional blue light from the LED array. Some of the blue light is absorbed by the organic phosphor composite and the phosphor molecules are excited and re-emit light at longer wavelengths due to the PL process. The output light consists of scattered blue light plus phosphor generated broadband yellow light, thus making white light. The diffuser was made up of a plastic substrate coated with an organic composite of small molecule fluorescent material zinc(II)bis(8-hydroxyquinoline) (Znq2) doped with different percentages of electro-phosphorescent metal complex iridium(III)bis(2-methyldibenzo-[f, h] quinoxaline) (acetylacetonate) ([Ir(MDQ)2(acac)]). By means of changing the concentration and the thickness of the phosphor composite material the colour coordinates of white light were achieved. The CIE coordinates and correlated colour temperature were calculated for various thicknesses and phosphor composite concentrations and the results are reported. (paper)

  15. A Study of the Blue-Light-Dependent Phosphorylation, Degradation, and Photobody Formation of Arabidopsis CRY2

    Institute of Scientific and Technical Information of China (English)

    Ze-Cheng Zuo; Ying-Ying Meng; Xu-Hong Yu; Zeng-Lin Zhang; De-Shun Feng; Shih-Fan Sun; Bin Liu; Chen-Tao Lin

    2012-01-01

    Arabidopsis cryptochrome 2 (CRY2) is a blue-light receptor mediating blue-light inhibition of hypocotyl elongation and photoperiodic promotion of floral initiation.CRY2 is a constitutive nuclear protein that undergoes blue-light-dependent phosphoryiation,ubiquitination,photobody formation,and degradation in the nucleus,but the relationship between these blue-light-dependent events remains unclear.it has been proposed that CRY2 phosphorylation triggers a conformational change responsible for the subsequent ubiquitination and photobody formation,leading to CRY2 function and/or degradation.We tested this hypothesis by a structure-function study,using mutant CRY2-GFP fusion proteins expressed in transgenic Arabidopsis.We show that changes of lysine residues of the NLS (Nuclear Localization Signal) sequence of CRY2 to arginine residues partially impair the nuclear importation of the CRY2K541R and CRY2K554/5R mutant proteins,resulting in reduced phosphorylation,physiological activities,and degradation in response to blue light.In contrast to the wild-type CRY2 protein that forms photobodies exclusively in the nucleus,the CRY2K541R and CRY2K554/5R mutant proteins form protein bodies in both the nucleus and cytosol in response to blue light.These results suggest that photoexcited CRY2 molecules can aggregate to form photobody-like structure without the nucleus-dependent protein modifications or the association with the nuclear CRY2-interacting proteins.Taken together,the observation that CRY2 forms photobodies markedly faster than CRY2 phosphorylation in response to blue light,we hypothesize that the photoexcited cryptochromes form oligomers,preceding other biochemical changes of CRY2,to facilitate photobody formation,signal amplification,and propagation,as well as desensitization by degradation.

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

    Directory of Open Access Journals (Sweden)

    Quentin eThommen

    2015-02-01

    Full Text Available 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. LOVHK is a blue light photoreceptor under circadian control, that is required for circadian clock function. An involvement of Rhodopsin-HK (RhodHK is also conceivable since rhodopsin photoreceptors mediate blue to green light input in animal circadian clocks.Here, we probe the role of LOVHK and RhodHK 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

  17. Direct involvement of hydrogen peroxide in curvature of wheat coleoptile in blue-light-treated and dark-grown coleoptiles

    International Nuclear Information System (INIS)

    Blue-light-induced photomorphogenesis is the sum total of a sequence of phenomena involving absorption of light by specific receptors, generation of a signal, processing transmembrane transport of signal, and the activation of a cascade of reactions in the cell interior. Though four blue-light receptors cryptochrome1, cryptochrome2, phototropin1, and phototropin2 have been identified, the signal transduction events associated with blue-light receptor activation are not understood. In this report, we demonstrate the generation and spatiotemporal distribution of H2O2 in wheat coleoptile in response to blue light. Interception of the free-radical generation pathways dithiothreitol and propyl gallate rendered wheat coleoptile tips phototropically non-responsive. Unilateral application of H2O2 onto the sub-apical region of a growing coleoptile brought about curvature in dark. Blue light also caused lipid peroxidation and augmented membrane rigidity of coleoptile cell membranes. We conclude that H2O2 can act as a translocating second messenger that could bring about coleoptile curvature, and the signaling events may trigger Ca2+ signaling cascades, changes in gene expression, and protein modifications

  18. The blue light-dependent phosphorylation of the CCE domain determines the photosensitivity of Arabidopsis CRY2.

    Science.gov (United States)

    Wang, Qin; Barshop, William D; Bian, Mingdi; Vashisht, Ajay A; He, Reqing; Yu, Xuhong; Liu, Bin; Nguyen, Paula; Liu, Xuanming; Zhao, Xiaoying; Wohlschlegel, James A; Lin, Chentao

    2015-04-01

    Arabidopsis cryptochrome 2 (CRY2) is a blue light receptor that mediates light inhibition of hypocotyl elongation and long-day promotion of floral initiation. CRY2 is known to undergo blue light-dependent phosphorylation, which is believed to serve regulatory roles in the function of CRY2. We report here on a biochemical and genetics study of CRY2 phosphorylation. Using mass spectrometry analysis, we identified three serine residues in the CCE domain of CRY2 (S588, S599, and S605) that undergo blue light-dependent phosphorylation in Arabidopsis seedlings. A study of serine-substitution mutations in the CCE domain of CRY2 demonstrates that CRY2 contains two types of phosphorylation in the CCE domain, one in the serine cluster that causes electrophoretic mobility upshift and the other outside the serine cluster that does not seem to cause mobility upshift. We showed that mutations in the serine residues within and outside the serine cluster diminished blue light-dependent CRY2 phosphorylation, degradation, and physiological activities. These results support the hypothesis that blue light-dependent phosphorylation of the CCE domain determines the photosensitivity of Arabidopsis CRY2. PMID:25792146

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

    International Nuclear Information System (INIS)

    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

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

    Science.gov (United States)

    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.

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

    Energy Technology Data Exchange (ETDEWEB)

    Abbaszadeh, D.; Wetzelaer, G. A. H. [Molecular Electronics, Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 4, 9747 AG, Groningen (Netherlands); Dutch Polymer Institute, P.O. Box 902, 5600 AX, Eindhoven (Netherlands); Nicolai, H. T. [TNO/Holst Centre, High Tech Campus 31, 5605 KN, Eindhoven (Netherlands); Blom, P. W. M., E-mail: blom@mpip-mainz.mpg.de [Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz (Germany); Department of Physics, Faculty of Science, King Abdulaziz University, Jeddah (Saudi Arabia)

    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.

  2. Phase collapse caused by blue-light irradiation in a cyanobridged coordination polymer

    International Nuclear Information System (INIS)

    In this work, we report a photoinduced phase transition, light-induced phase collapse, using rubidium manganese hexacyanoferrate, RbI0.43MnII[FeIII(CN)6]0.81·3H2O, which does not exhibit a phase transition upon changing the temperature. However, when this material is irradiated with blue light at temperature around 100-200 K, the MnII-FeIII phase collapses and the valence isomer MnIII-FeII phase appears. The MnII-FeIII phase is perfectly recovered as the temperature increased. Theoretical analysis suggests that the initial MnII-FeIII phase is a thermodynamically metastable phase, trapped at a local free-energy minimum, while the photogenerated MnIII-FeII phase is the true thermodynamically stable phase below 230 K

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

    Energy Technology Data Exchange (ETDEWEB)

    Chen Ping; Duan Yu; Xie Wenfa; Zhao Yi; Hou Jingying; Liu Shiyong [State Key Laboratory on Integrated Optoelectronics, College of Electronic Science and Engineering, Jilin University, 2699 Qianjin Street, Changchun 130012 (China); Zhang Liying; Li Bin, E-mail: chenping0329@gmail.co, E-mail: syliu@jlu.edu.c [Key Laboratory of Excited State Processes, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun, 130033 (China)

    2009-03-07

    We demonstrate efficient white organic light-emitting devices (WOLEDs) based on an orange phosphorescent iridium complex bis(2-(2-fluorphenyl)-1,3-benzothiozolato-N, C{sup 2'})iridium(acetylacetonate) in combination with blue phosphorescent dye bis[(4, 6-difluorophenyl)-pyridinato-N,C{sup 2})](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{sup -1} and a maximum luminance of 39 050 cd m{sup -2}. The power efficiency is 8.7 lm W{sup -1} at 100 cd m{sup -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{sup -2}.

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

    Science.gov (United States)

    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 (Pteeth, digitized with a blue light scanner, had good repeatability and reproducibility. PMID:27350856

  5. Blue Light Hazard and Risk Group Classification of 8 W LED Tubes, Replacing Fluorescent Tubes, through Optical Radiation Measurements

    Directory of Open Access Journals (Sweden)

    Francesco Leccese

    2015-09-01

    Full Text Available In this paper, the authors discuss the results of a measurement survey of artificial optical radiation emitted by 8 W LED tubes suitable for the substitution of 18 W fluorescent lamps used for general lighting. For both types of lamps, three different color temperatures were chosen, 3000 K, 4000 K, and 6000 K. These measurements were performed to evaluate the photobiological safety of the sources. The radiance and irradiance values have been measured in a wide range of wavelengths (180–3000 nm. The measurement results obtained for the LED tubes have been compared to those of similar measurements obtained for fluorescent lamps. The analysis has been focused on the range of wavelengths 300–700 nm, the blue light range, which turned out to be defining for the risk groups of the lamps. This classification is a function of the maximum permissible exposure time as indicated in the European Standard EN 62471 on the photobiological safety of lamps and lamp systems.

  6. Human Lens Transmission of Blue Light: A Comparison of Autofluorescence-Based and Direct Spectral Transmission Determination

    DEFF Research Database (Denmark)

    Broendsted, Adam Elias; Stormly Hansen, Michael; Lund-Andersen, Henrik;

    2011-01-01

    Purpose: Direct measurement of the transmission of light through the human lens is not possible in vivo unless invasive techniques are used. In the current study, a reliable in vivo estimate of the transmission of blue light through the lens was assessed by comparing an indirect and noninvasive...... method based on autofluorescence measurements with a direct method. Methods: Total transmission of blue light was measured in human donor lenses using a direct method applicable only in vitro and compared with transmittance estimates made by an in vivo applicable autofluorescence technique. Results......: Human lens transmission of blue light decreases with age by 0.7-0.8% per year at 480 nm. The comparison of methods showed that the autofluorescence-based method correlated significantly with the direct measurements (R = 0.83, p <0.001) and acceptable agreement between the two methods was found...

  7. Killing Bacterial Spores with Blue Light: When Innate Resistance Meets the Power of Light

    OpenAIRE

    St. Denis, Tyler G.; Dai, Tianhong; Michael R Hamblin

    2012-01-01

    This article is a highlight of the study by Maclean et al. in this issue of Photochemistry and Photobiology describing the sporicidal effects 405 nm visible light alone on endospores of the Clostridium and Bacillus genera. 1.73 kJ cm−2 was capable of reducing endospore colony-forming units by up to 4-log10. These findings have never been previously demonstrated and may be incorporated into decontamination methods that span medical, military and food preparatory applications.

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

    Science.gov (United States)

    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

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    Spalding, E. P.; Cosgrove, D. J.

    1989-01-01

    Blue-light (BL)-induced suppression of elongation of etiolated Cucumis sativus L. hypocotyls began after a 30-s lag time, which was halved by increasing the fluence rate from 10 to 100 micromoles m-2 s-1. Prior to the growth suppression, the plasma-membrane of the irradiated cells depolarized by as much as 100 mV, then returned within 2-3 min to near its initial value. The potential difference measured with surface electrodes changed with an identical time course but opposite polarity. The lag time for the change in surface potential showed an inverse dependence on fluence rate, similar to the lag for the growth inhibition. Green light and red light caused neither the electrical response nor the rapid inhibition of growth. The depolarization by BL did not propagate to nonirradiated regions and exhibited a refractory period of about 10 min following a BL pulse. Fluence-response relationships for the electrical and growth responses provide correlational evidence that the plasma-membrane depolarization reflects an event in the transduction chain of this light-growth response.

  11. Mental Health Benefits of Long-Term Exposure to Residential Green and Blue Spaces: A Systematic Review

    Directory of Open Access Journals (Sweden)

    Mireia Gascon

    2015-04-01

    Full Text Available Many studies conducted during the last decade suggest the mental health benefits of green and blue spaces. We aimed to systematically review the available literature on the long-term mental health benefits of residential green and blue spaces by including studies that used standardized tools or objective measures of both the exposures and the outcomes of interest. We followed the PRISMA statement guidelines for reporting systematic reviews and meta-analysis. In total 28 studies were included in the systematic review. We found limited evidence for a causal relationship between surrounding greenness and mental health in adults, whereas the evidence was inadequate in children. The evidence was also inadequate for the other exposures evaluated (access to green spaces, quality of green spaces, and blue spaces in both adults and children. The main limitation was the limited number of studies, together with the heterogeneity regarding exposure assessment. Given the increase in mental health problems and the current rapid urbanization worldwide, results of the present systematic review should be taken into account in future urban planning. However, further research is needed to provide more consistent evidence and more detailed information on the mechanisms and the characteristics of the green and blue spaces that promote better mental health. We provide recommendations for future studies in order to provide consistent and evidence-based recommendations for policy makers.

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

    Science.gov (United States)

    Miao, Yan-Qin; Gao, Zhi-Xiang; Zhang, Ai-Qin; Li, Yuan-Hao; Wang, Hua; Jia, Hu-Sheng; Liu, Xu-Guang; Tsuboi, Taijuf

    2015-05-01

    Levofloxacin (LOFX), which is well-known as an antibiotic medicament, was shown to be useful as a 452-nm blue emitter for white organic light-emitting diodes (OLEDs). In this paper, the fabricated white OLED contains a 452-nm blue emitting layer (thickness of 30 nm) with 1 wt% LOFX doped in CBP (4,4’-bis(carbazol-9-yl)biphenyl) host and a 584-nm orange emitting layer (thickness of 10 nm) with 0.8 wt% DCJTB (4-(dicyanomethylene)-2-tert-butyl-6-(1,1,7,7-tetramethyljulolidin-4-yl-vinyl)-4H-pyran) doped in CBP, which are separated by a 20-nm-thick buffer layer of TPBi (2,2’,2”-(benzene-1,3,5-triyl)-tri(1-phenyl-1H-benzimidazole). A high color rendering index (CRI) of 84.5 and CIE chromaticity coordinates of (0.33, 0.32), which is close to ideal white emission CIE (0.333, 0.333), are obtained at a bias voltage of 14 V. Taking into account that LOFX is less expensive and the synthesis and purification technologies of LOFX are mature, these results indicate that blue fluorescence emitting LOFX is useful for applications to white OLEDs although the maximum current efficiency and luminance are not high. The present paper is expected to become a milestone to using medical drug materials for OLEDs. Project supported by the Program for New Century Excellent Talents in University of Ministry of Education of China (Grant No. NCET-13-0927), the International Science & Technology Cooperation Program of China (Grant No. 2012DFR50460), the National Natural Science Foundation of China (Grant Nos. 21101111 and 61274056), and the Shanxi Provincial Key Innovative Research Team in Science and Technology, China (Grant No. 2012041011).

  13. Ferrochelatase is a conserved downstream target of the blue light-sensing White collar complex in fungi

    OpenAIRE

    Idnurm, Alexander; Heitman, Joseph

    2010-01-01

    Light is a universal signal perceived by organisms, including fungi, in which light regulates common and unique biological processes depending on the species. Previous research has established that conserved proteins, originally called White collar 1 and 2 from the ascomycete Neurospora crassa, regulate UV/blue light sensing. Homologous proteins function in distant relatives of N. crassa, including the basidiomycetes and zygomycetes, which diverged as long as a billion years ago. Here we cond...

  14. Regulation by Blue Light of the fluffy Gene Encoding a Major Regulator of Conidiation in Neurospora crassa

    OpenAIRE

    Olmedo, María; Ruger-Herreros, Carmen; Corrochano, Luis M.

    2010-01-01

    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 transcripti...

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

  17. Highly efficient organic blue light emitting devices using doped transport layers

    Energy Technology Data Exchange (ETDEWEB)

    Seidler, Nico; Reineke, Sebastian; Walzer, Karsten; Luessem, Bjoern; Leo, Karl [Institut fuer Angewandte Physik/Photophysik, Technische Universitaet Dresden, D-01062 Dresden (Germany); Tomkeviciene, Ausra; Grazulevicius, Juozas V. [Department of Organic Technology, Kaunas University of Technology, Kaunas LT-50254 (Lithuania)

    2009-07-01

    In contrast to red and green OLEDs, blue light emitting devices are still far away from the theoretical limit of about 20 % external quantum efficiency. The best results so far have been achieved involving ultrahigh energy gap organosilicon compounds. Due to their poor transport properties, high efficiencies are obtained only at low current densities and high voltages. We used the blue phosphorescent emitter iridium(III)bis[(4,6-di-fluorophenyl)-pyridinato-N,C{sup 2{sup '}}]picolinate (FIrpic) as a dopant in the host material 3,6-di(9-carbazolyl)-9-(2-ethylhexyl)carbazole, which possesses both a large triplet exciton energy and good charge carrier transport properties. It was therewith possible to efficiently confine the triplet excitons on the emitting molecules and keep the recombination zone away from the blocking layers. This results in a high external quantum efficiency of 13.1 % at a brightness of 1,000 cd/m{sup 2}. Due to the superior charge carrier injection properties provided by the doped transport layers, this brightness could be achieved at low voltages of only 4.0 V, resulting in a high power efficiency of 22.5 lm/W.

  18. Sleep-Wake Actigraphy and Light Exposure During Spaceflight - Short

    Science.gov (United States)

    Czeisler, Charles A.; Wright, Kenneth P., Jr.; Ronda, Joseph

    2009-01-01

    Sleep-Wake Actigraphy and Light Exposure During Spaceflight - Short (Sleep-Short) will examine the effects of spaceflight on the sleep of the astronauts during space shuttle missions. Advancing state-of-the-art technology for monitoring, diagnosing and assessing treatment of sleep patterns is vital to treating insomnia on Earth and in space.

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

  1. Optical dating of archaeological samples using a single aliquot of quartz stimulated by blue light

    International Nuclear Information System (INIS)

    The single aliquot additive dose method of equivalent dose determination was applied to quartz from heated archaeological materials, using luminescence stimulated by blue light. The quartz was extracted from pieces of pottery and kiln in an area of archaeological interest in Suwon region, south of Seoul, Korea. The dates obtained were in good agreement with the ages derived by archaeological evidence. It is concluded that the additive dose single aliquot method of determining equivalent dose, with correction for re-use of the aliquot, should contribute significantly to optically stimulated luminescence dating procedures, particularly when the amount of sample separated is limited. Additionally, some luminescence images from quartz samples using a CCD camera are presented and relationships between AGTL, TL and OSL are discussed. (author)

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

    Science.gov (United States)

    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

  3. Phototransferred thermoluminescence from alpha-Al sub 2 O sub 3 :C using blue light emitting diodes

    CERN Document Server

    Bulur, E

    1999-01-01

    Phototransferred thermoluminescence (PTTL) from alpha-Al sub 2 O sub 3 :C single crystals was studied using a blue light emitting diode (LED) for phototransfer of charges from deep traps to the main dosimetry trap. The dose response was found to be linear in the region from approx 5 mGy to approx 5 Gy. It was observed that the corresponding deep traps were located near 500 deg. C and heating to temperatures >600 deg. C removes the PTTL effect induced by the light from the blue LED. The thermal activation energy of the source traps involved in the PTTL production was calculated as 3.23 eV.

  4. Theoretical Design of Blue-light-emitting Material Based on 1,2,3-Benzotriazole-based Derivative

    Institute of Scientific and Technical Information of China (English)

    HU Bo; YAO Chan; HUANG Xu-Ri

    2011-01-01

    Theoretically,1,2,3-benzotriazole(BT)-based derivative is designed by the struc-tural tuning in 2,1,3-benzothiadiazole(BTD)-based derivative and presents potential for applications in organic light-emitting diodes(OLEDs).Calculations show that the emission spectrum of BT-based derivative is located at the blue scope,so it can act as a blue-light-emitting material.Importantly,the oscillator strength of emission spectrum is significantly enhanced by replacing BTD with BT,implying it possess large fluorescent intensity.Additionally,BT-based derivative exhibits improved hole transportation with respect to the BTD-based derivative.

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

    Directory of Open Access Journals (Sweden)

    Kenitz J Dustin

    2005-08-01

    Full Text Available Abstract Background Although specific light attributes, such as color and fluence rate, influence plant growth and development, researchers generally cannot control the fine spectral conditions of artificial plant-growth environments. Plant growth chambers are typically outfitted with fluorescent and/or incandescent fixtures that provide a general spectrum that is accommodating to the human eye and not necessarily supportive to plant development. Many studies over the last several decades, primarily in Arabidopsis thaliana, have clearly shown that variation in light quantity, quality and photoperiod can be manipulated to affect growth and control developmental transitions. Light emitting diodes (LEDs has been used for decades to test plant responses to narrow-bandwidth light. LEDs are particularly well suited for plant growth chambers, as they have an extraordinary life (about 100,000 hours, require little maintenance, and use negligible energy. These factors render LED-based light strategies particularly appropriate for space-biology as well as terrestrial applications. However, there is a need for a versatile and inexpensive LED array platform where individual wavebands can be specifically tuned to produce a series of light combinations consisting of various quantities and qualities of individual wavelengths. Two plans are presented in this report. Results In this technical report we describe the practical construction of tunable red-green-blue LED arrays to support research in plant growth and development. Two light fixture designs and corresponding circuitry are presented. The first is well suited for a laboratory environment for use in a finite area with small plants, such as Arabidopsis. The second is expandable and appropriate for growth chambers. The application of these arrays to early plant developmental studies has been validated with assays of hypocotyl growth inhibition/promotion and phototropic curvature in Arabidopsis seedlings

  6. Anthocyanin Accumulation Mediated by Blue Light and Cytokinin in Arabidopsis Seedlings

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    It has been reported that pigmentation in plants is stimulated by light and cytokinin (CTK); however, the signaling pathways and the relationship between light and CTK involved in the regulation of anthocyanin accumulation remain to be elucidated. We investigated (i) the role of blue light (BL) and CTK in anthocyanin accumulation; and (ii) the relationship between BL and CTK in wild type (WT) and hy4 mutants of Arabidopsis thaliana. Two-d-old seedlings grown on medium with or without kinetin (KT) or zeatin (ZT) in darkness were irradiated using BL at different fluence rates for 3 d before the anthocyanin content was determined using a spectrophotometric method. Anthocyanin accumulation was strongly induced by BL in WT seedlings but not in hy4 seedlings, which demonstrated that CRY1 is the main photoreceptor for BL. Both KT and ZT enhanced the response of the WT seedlings to BL in a dose-dependent manner, whereas they were not sufficient to promote anthocyanin accumulation in darkness. In addition, data from experiments using the hy4 mutant showed that the CTK effect of BL was also CRY1-dependent. The results from experiments with three different treatment programs showed that the relationship between BL and KT in anthocyanin accumulation of Arabidopsis seedlings seems neither multiplicative nor additive coaction, but rather interaction. BL is necessary for anthocyanin accumulation, and KT might be involved in the BL signaling pathway.

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

    Science.gov (United States)

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

    2016-03-01

    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.

  8. Degradation behaviors of high power GaN-based blue light emitting diodes

    International Nuclear Information System (INIS)

    The degradation mechanism of high power InGaN/GaN blue light emitting diodes (LEDs) is investigated in this paper. The LED samples were stressed at room temperature under 350-mA injection current for about 400 h. The light output power of the LEDs decreased by 35% during the first 100 h and then remained almost unchanged, and the reverse current at −5 V increased from 10−9 A to 10−7 A during the aging process. The power law, whose meaning was re-illustrated by the improved rate equation, was used to analyze the light output power-injection current (L—I) curves. The analysis results indicate that nonradiative recombination, Auger recombination, and the third-order term of carriers overflow increase during the aging process, all of which may be important reasons for the degradation of LEDs. Besides, simulating L—I curves with the improved rate equation reveal that higher-than-third-order terms of carriers overflow may not be the main degradation mechanism, because they change slightly when the LED is stressed

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

    Science.gov (United States)

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

    2016-01-01

    BLUF (blue light sensor using flavin) domains regulate the activity of various enzymatic effector domains in bacteria and euglenids. BLUF features a unique photoactivation through restructuring of the hydrogen-bonding network as opposed to a redox reaction or an isomerization of the chromophore. A conserved glutamine residue close to the flavin chromophore plays a central role in the light response, but the underlying modification is still unclear. We labelled this glutamine with 15N in two representative BLUF domains and performed time-resolved infrared double difference spectroscopy. The assignment of the signals was conducted by extensive quantum chemical calculations on large models with 187 atoms reproducing the UV-vis and infrared signatures of BLUF photoactivation. In the dark state, the comparatively low frequency of 1,667 cm−1 is assigned to the glutamine C=O accepting a hydrogen bond from tyrosine. In the light state, the signature of a tautomerised glutamine was extracted with the C=N stretch at ~1,691 cm−1 exhibiting the characteristic strong downshift by 15N labelling. Moreover, an indirect isotope effect on the flavin C4=O stretch was found. We conclude that photoactivation of the BLUF receptor does not only involve a rearrangement of hydrogen bonds but includes a change in covalent bonds of the protein. PMID:26947391

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

    Science.gov (United States)

    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

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

    Science.gov (United States)

    Mickens, Matthew A.

    2012-01-01

    Growing vegetable crops in space will be an essential part of sustaining astronauts during long-term missions. To drive photosynthesis, red and blue light-emitting diodes (LEDs) have attracted attention because of their efficiency, longevity, small size, and safety. In efforts to optimize crop production, there have also been recent interests in analyzing the subtle effects of green light on plant growth, and to determine if it serves as a source of growth enhancement or suppression. A comparative study was performed on two short cycle crops of lettuce (Outredgeous) and radish (Cherry Bomb) grown under two light treatments. The first treatment being red and blue LEDs, and the second treatment consisting of white fluorescent lamps which contain a portion of green light. In addition to comparing biomass production, physiological characterizations were conducted on how the light treatments influence morphology, water use, chlorophyll content, and the production of A TP within plant tissues.

  12. Photomorphogenesis, photosynthesis, and seed yield of wheat plants grown under red light-emitting diodes (LEDs) with and without supplemental blue lighting

    Science.gov (United States)

    Goins, G. D.; Yorio, N. C.; Sanwo, M. M.; Brown, C. S.; Sager, J. C. (Principal Investigator)

    1997-01-01

    Red light-emitting diodes (LEDs) are a potential light source for growing plants in spaceflight systems because of their safety, small mass and volume, wavelength specificity, and longevity. Despite these attractive features, red LEDs must satisfy requirements for plant photosynthesis and photomorphogenesis for successful growth and seed yield. To determine the influence of gallium aluminium arsenide (GaAlAs) red LEDs on wheat photomorphogenesis, photosynthesis, and seed yield, wheat (Triticum aestivum L., cv. 'USU-Super Dwarf') plants were grown under red LEDs and compared to plants grown under daylight fluorescent (white) lamps and red LEDs supplemented with either 1% or 10% blue light from blue fluorescent (BF) lamps. Compared to white light-grown plants, wheat grown under red LEDs alone demonstrated less main culm development during vegetative growth through preanthesis, while showing a longer flag leaf at 40 DAP and greater main culm length at final harvest (70 DAP). As supplemental BF light was increased with red LEDs, shoot dry matter and net leaf photosynthesis rate increased. At final harvest, wheat grown under red LEDs alone displayed fewer subtillers and a lower seed yield compared to plants grown under white light. Wheat grown under red LEDs+10% BF light had comparable shoot dry matter accumulation and seed yield relative to wheat grown under white light. These results indicate that wheat can complete its life cycle under red LEDs alone, but larger plants and greater amounts of seed are produced in the presence of red LEDs supplemented with a quantity of blue light.

  13. From Plant Infectivity to Growth Patterns: The Role of Blue-Light Sensing in the Prokaryotic World

    Directory of Open Access Journals (Sweden)

    Aba Losi

    2014-01-01

    Full Text Available Flavin-based photoreceptor proteins of the LOV (Light, Oxygen, and Voltage and BLUF (Blue Light sensing Using Flavins superfamilies are ubiquitous among the three life domains and are essential blue-light sensing systems, not only in plants and algae, but also in prokaryotes. Here we review their biological roles in the prokaryotic world and their evolution pathways. An unexpected large number of bacterial species possess flavin-based photosensors, amongst which are important human and plant pathogens. Still, few cases are reported where the activity of blue-light sensors could be correlated to infectivity and/or has been shown to be involved in the activation of specific genes, resulting in selective growth patterns. Metagenomics and bio-informatic analysis have only recently been initiated, but signatures are beginning to emerge that allow definition of a bona fide LOV or BLUF domain, aiming at better selection criteria for novel blue-light sensors. We also present here, for the first time, the phylogenetic tree for archaeal LOV domains that have reached a statistically significant number but have not at all been investigated thus far.

  14. Anatomical features of pepper plants (Capsicum annuum L.) grown under red light-emitting diodes supplemented with blue or far-red light

    Science.gov (United States)

    Schuerger, A. C.; Brown, C. S.; Stryjewski, E. C.

    1997-01-01

    Pepper plants (Capsicum annuum L. cv., Hungarian Wax) were grown under metal halide (MH) lamps or light-emitting diode (LED) arrays with different spectra to determine the effects of light quality on plant anatomy of leaves and stems. One LED (660) array supplied 90% red light at 660 nm (25nm band-width at half-peak height) and 1% far-red light between 700-800nm. A second LED (660/735) array supplied 83% red light at 660nm and 17% far-red light at 735nm (25nm band-width at half-peak height). A third LED (660/blue) array supplied 98% red light at 660nm, 1% blue light between 350-550nm, and 1% far-red light between 700-800nm. Control plants were grown under broad spectrum metal halide lamps. Plants were gron at a mean photon flux (300-800nm) of 330 micromol m-2 s-1 under a 12 h day-night photoperiod. Significant anatomical changes in stem and leaf morphologies were observed in plants grown under the LED arrays compared to plants grown under the broad-spectrum MH lamp. Cross-sectional areas of pepper stems, thickness of secondary xylem, numbers of intraxylary phloem bundles in the periphery of stem pith tissues, leaf thickness, numbers of choloplasts per palisade mesophyll cell, and thickness of palisade and spongy mesophyll tissues were greatest in peppers grown under MH lamps, intermediate in plants grown under the 660/blue LED array, and lowest in peppers grown under the 660 or 660/735 LED arrays. Most anatomical features of pepper stems and leaves were similar among plants grown under 660 or 660/735 LED arrays. The effects of spectral quality on anatomical changes in stem and leaf tissues of peppers generally correlate to the amount of blue light present in the primary light source.

  15. Multi-watt power blue light generation by intracavity sum- frequency-mixing in KTiOPO4 crystal.

    Science.gov (United States)

    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

  16. Color Degradation of Textiles with Natural Dyes and of Blue Scale Standards Exposed to White LED Lamps:Evaluation of White LED Lamps for Effectiveness as Museum Lighting

    Science.gov (United States)

    Ishii, Mie; Moriyama, Takayoshi; Toda, Masahiro; Kohmoto, Kohtaro; Saito, Masako

    White light-emitting diodes (LED) are well suited for museum lighting because they emit neither UV nor IR radiation, which damage artifacts. The color degradation of natural dyes and blue scale standards (JIS L 0841) by white LED lamps are examined, and the performance of white LED lamps for museum lighting is evaluated. Blue scale standard grades 1-6 and silk fabrics dyed with 22 types of natural dyes classified as mid to highly responsive in a CIE technical report (CIE157:2004) were exposed to five types of white LED lamps using different luminescence methods and color temperatures. Color changes were measured at each 15000 lx·hr (500 lx at fabric surface × 300 hr) interval ten times. The accumulated exposure totaled 150000 lx·hr. The data on conventional white LED lamps and previously reported white fluorescent (W) and museum fluorescent (NU) lamps was evaluated. All the white LED lamps showed lower fading rates compared with a W lamp on a blue scale grade 1. The fading rate of natural dyes in total was the same between an NU lamp (3000 K) and a white LED lamp (2869 K). However, yellow natural dyes showed higher fading rates with the white LED lamp. This tendency is due to the high power characteristic of the LED lamp around 400-500 nm, which possibly contributes to the photo-fading action on the dyes. The most faded yellow dyes were Ukon (Curcuma longa L.) and Kihada (Phellodendron amurense Rupr.), and these are frequently used in historic artifacts such as kimono, wood-block prints, and scrolls. From a conservation point of view, we need to continue research on white LED lamps for use in museum lighting.

  17. Chemical magnetoreception: bird cryptochrome 1a is excited by blue light and forms long-lived radical-pairs.

    Directory of Open Access Journals (Sweden)

    Miriam Liedvogel

    Full Text Available Cryptochromes (Cry have been suggested to form the basis of light-dependent magnetic compass orientation in birds. However, to function as magnetic compass sensors, the cryptochromes of migratory birds must possess a number of key biophysical characteristics. Most importantly, absorption of blue light must produce radical pairs with lifetimes longer than about a microsecond. Cryptochrome 1a (gwCry1a and the photolyase-homology-region of Cry1 (gwCry1-PHR from the migratory garden warbler were recombinantly expressed and purified from a baculovirus/Sf9 cell expression system. Transient absorption measurements show that these flavoproteins are indeed excited by light in the blue spectral range leading to the formation of radicals with millisecond lifetimes. These biophysical characteristics suggest that gwCry1a is ideally suited as a primary light-mediated, radical-pair-based magnetic compass receptor.

  18. Chemical Magnetoreception: Bird Cryptochrome 1a Is Excited by Blue Light and Forms Long-Lived Radical-Pairs

    Science.gov (United States)

    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

  19. Characterization of a FEL lamp type source towards a blue light irradiance intercomparison in medical field

    Science.gov (United States)

    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%.

  20. Characterization of a FEL lamp type source towards a blue light irradiance intercomparison in medical field

    Energy Technology Data Exchange (ETDEWEB)

    Ferreira, A F G Jr, E-mail: agentil@ipt.br [Laboratorio de Equipamentos Elotricos e Opticos, Instituto de Pesquisas Tecnologicas do Estado de Sao Paulo, Avenida Professor Almeida Prado, 532, 05508-901 (Brazil)

    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 (registered) 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%.

  1. Characterization of a FEL lamp type source towards a blue light irradiance intercomparison in medical field

    International Nuclear Information System (INIS)

    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 (registered) 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. Photodynamic inactivation of methylene blue and tungsten-halogen lamp light against food pathogen Listeria monocytogenes.

    Science.gov (United States)

    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

  3. AZO/Ag/AZO anode for resonant cavity red, blue, and yellow organic light emitting diodes

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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

  5. Chemical magnetoreception: bird cryptochrome 1a is excited by blue light and forms long-lived radical-pairs.

    OpenAIRE

    Miriam Liedvogel; Kiminori Maeda; Kevin Henbest; Erik Schleicher; Thomas Simon; Timmel, Christiane R.; Hore, P. J.; Henrik Mouritsen

    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 we...

  6. Chemical Magnetoreception: Bird Cryptochrome 1a Is Excited by Blue Light and Forms Long-Lived Radical-Pairs

    OpenAIRE

    Liedvogel, M; Maeda, K.; Henbest, K; Schleicher, E; Simon, T.; Timmel, CR; Hore, PJ; Mouritsen, H

    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 we...

  7. Bright light in elderly subjects with nonseasonal major depressive disorder: a double blind randomised clinical trial using early morning bright blue light comparing dim red light treatment

    Directory of Open Access Journals (Sweden)

    van Someren Eus JW

    2008-07-01

    Full Text Available Abstract Background Depression frequently occurs in the elderly. Its cause is largely unknown, but several studies point to disturbances of biological rhythmicity. In both normal aging, and depression, the functioning of the suprachiasmatic nucleus (SCN is impaired, as evidenced by an increased prevalence of day-night rhythm perturbations, such as sleeping disorders. Moreover, the inhibitory SCN neurons on the hypothalamus-pituitary adrenocortical axis (HPA-axis have decreased activity and HPA-activity is enhanced, when compared to non-depressed elderly. Using bright light therapy (BLT the SCN can be stimulated. In addition, the beneficial effects of BLT on seasonal depression are well accepted. BLT is a potentially safe, nonexpensive and well accepted treatment option. But the current literature on BLT for depression is inconclusive. Methods/Design This study aims to show whether BLT can reduce non-seasonal major depression in elderly patients. Randomized double blind placebo controlled trial in 126 subjects of 60 years and older with a diagnosis of major depressive disorder (MDD, DSM-IV/SCID-I. Subjects are recruited through referrals of psychiatric outpatient clinics and from case finding from databases of general practitioners and old-people homes in the Amsterdam region. After inclusion subjects are randomly allocated to the active (bright blue light vs. placebo (dim red light condition using two Philips Bright Light Energy boxes type HF 3304 per subject, from which the light bulbs have been covered with bright blue- or dim red light- permitting filters. Patients will be stratified by use of antidepressants. Prior to treatment a one-week period without light treatment will be used. At three time points several endocrinological, psychophysiological, psychometrically, neuropsychological measures are performed: just before the start of light therapy, after completion of three weeks therapy period, and three weeks thereafter. Discussion If BLT

  8. Effects of light exposure on the TL dating of pottery

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Bleaching experiments on Chinese pottery fine grains were conducted under sunlight and laboratory light conditions. It is found that the thermoluminescence (TL) at high temperatures can be bleached significantly, but no effects were observed on TL signals used for the pre-dose dating technique. It is concluded that the pre-dose dating technique can be applied to samples even after light exposures. Pottery samples of Tang Dynasty and New Stone Age were studied. Modifications to routine pre-dose dating technique are proposed with adding preheat procedures and using saturation exponential fitting for the sensitivity change data. The modified technique can extend the dating range to New Stone Age.

  9. Effect of light on the content of photosynthetically active pigments in plants. Pt. 4. Chromatic adaption in blue-green algae Anabaena cylindrica and A. variabilis

    Energy Technology Data Exchange (ETDEWEB)

    Czeczuga, B.

    1986-07-15

    The photosynthetic pigments (chlorophyll a, carotenoids and phycobiliprotein pigments) of two species of the genus Anabaena grown in white, red, yellow, green and blue light were examined. The highest concentration of the cells was observed in the sample with red light in case of the both species, and the smallest with blue light. The biggest amounts of chlorophyll a and carotenoids were included in the cells of samples with the yellow and the smallest in case of the red light. The ratio of two phycobiliproteins is as follows: - in Anabaena cylindrica: the highest amount of C-phycocyanin in the cells was observed in the case of the red light, and C-phycoerytherin was found in the blue light; - in Anabaena variabiles: the highest amount of C-phycocyanien in the cells was found in case of the yellow light, and allophycocyanin was found in the blue light.

  10. Acne phototherapy using UV-free high-intensity narrow-band blue light: a three-center clinical study

    Science.gov (United States)

    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.

  11. Visible-light-induced blue MoO3–C3N4 composite with enhanced photocatalytic activity

    International Nuclear Information System (INIS)

    Highlights: • Novel MoO3–C3N4 composite was prepared by a mixing-calcination method. • The MoO3–C3N4 composite shows remarkably enhanced absorption of visible light. • The MoO3–C3N4 composite shows superior visible-light photocatalytic activity. - Abstract: Composite photocatalyst of blue MoO3/g-C3N4 (denoted as MoO3–C3N4) was prepared by a simple mixing-calcination method. The obtained MoO3–C3N4 composite contains a low amount of molybdenum blue and shows remarkably enhanced absorption of visible light and high efficiency for the degradation of methylene blue dye (MB) under visible light. The enhancement of visible light photocatalytic activity in MoO3–C3N4 is attributed to the synergetic effect: (i) the strong and wide absorption of visible light, (ii) the high separation and easy transfer of photogenerated electron–hole pairs at the heterojunction interfaces derived from the match of band position between the g-C3N4 and MoO3

  12. Poly(vinylpyrrolidone) supported copper nanoclusters: glutathione enhanced blue photoluminescence for application in phosphor converted light emitting devices

    Science.gov (United States)

    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

  13. In vitro and in vivo Efficacy of New Blue Light Emitting Diode Phototherapy Compared to Conventional Halogen Quartz Phototherapy for Neonatal Jaundice

    OpenAIRE

    Chang, Yun Sil; Hwang, Jong Hee; Kwon, Hyuk Nam; Choi, Chang Won; Ko, Sun Young; Park, Won Soon; Shin, Son Moon; Lee, Munhyang

    2005-01-01

    High intensity light emitting diodes (LEDs) are being studied as possible light sources for the phototherapy of neonatal jaundice, as they can emit high intensity light of narrow wavelength band in the blue region of the visible light spectrum corresponding to the spectrum of maximal bilirubin absorption. We developed a prototype blue gallium nitride LED phototherapy unit with high intensity, and compared its efficacy to commercially used halogen quartz phototherapy device by measuring both i...

  14. Efficient white phosphorescent organic light-emitting diodes consisting of orange ultrathin and blue mixed host emission layers

    Science.gov (United States)

    Sheng, Ren; Zuo, Liangmei; Xue, Kaiwen; Duan, Yu; Chen, Ping; Cheng, Gang; Zhao, Yi

    2016-08-01

    We have successfully demonstrated highly efficient white phosphorescent organic light-emitting diodes (OLEDs) by inserting an ultrathin non-doped orange layer within blue mixed host emission layer. The key feature of the novel device is the employment of blue mixed host and orange ultrathin layers, resulting in an extended recombination region and more balanced charge carrier. The maximum efficiencies of 33.8 lm W‑1 and 32.2 cd A‑1 are obtained. Moreover, the resulting white device achieves a slight efficiency roll-off and a high luminance at low operating voltage. Our versatile concept suggests a promising simple method to achieve high performance white OLEDs.

  15. Carcinogenesis related to intense pulsed light and UV exposure

    DEFF Research Database (Denmark)

    Hedelund, L; Lerche, C; Wulf, H C;

    2006-01-01

    preoperative UV-exposed mice (p=0.94) and from 22 to 23 weeks in pre- and postoperative UV-exposed mice (p=0.11). IPL rejuvenation of lightly pigmented skin did not induce pigmentary changes (p=1.00). IPL rejuvenation of UV-pigmented skin resulted in an immediate increased skin pigmentation and a subsequent......This study examines whether intense pulsed light (IPL) treatment has a carcinogenic potential itself or may influence ultraviolet (UV)-induced carcinogenesis. Secondly, it evaluates whether UV exposure may influence IPL-induced side effects. Hairless, lightly pigmented mice (n=144) received three...... IPL treatments at 2-week intervals. Simulated solar radiation was administered preoperatively [six standard erythema doses (SED) four times weekly for 11 weeks] as well as pre- and postoperatively (six SED four times weekly up to 26 weeks). Skin tumors were assessed weekly during a 12-month...

  16. Mechanism of blue-light-induced plasma-membrane depolarization in etiolated cucumber hypocotyls

    Science.gov (United States)

    Spalding, E. P.; Cosgrove, D. J.

    1992-01-01

    A large, transient depolarization of the plasma membrane precedes the rapid blue-light (BL)-induced growth suppression in etiolated seedlings of Cucumis sativus L. The mechanism of this voltage transient was investigated by applying inhibitors of ion channels and the plasma-membrane H(+)-ATPase, by manipulating extracellular ion concentrations, and by measuring cell input resistance and ATP levels. The depolarizing phase was not affected by Ca(2+)-channel blockers (verapamil, La3+) or by reducing extracellular free Ca2+ by treatment with ethylene glycol-bis(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid (EGTA). However, these treatments did reduce the rate of repolarization, indicating an inward movement of Ca2+ is involved. No effects of the K(+)-channel blocker tetraethylammonium (TEA+) were detected. Vanadate and KCN, used to inhibit the H(+)-ATPase, reduced or completely inhibited the BL-induced depolarization. Levels of ATP increased by 11-26% after 1-2 min of BL. Input resistance of trichrome cells, measured with double-barreled microelectrodes, remained constant during the onset of the depolarization but decreased as the membrane voltage became more positive than -90 mV. The results indicate that the depolarization mechanism initially involves inactivation of the H(+)-ATPase with subsequent transient activation of one or more types of ion channels.

  17. Photocatalytic Degradation of Methylene Blue under UV Light Irradiation on Prepared Carbonaceous TiO2

    Directory of Open Access Journals (Sweden)

    Zatil Amali Che Ramli

    2014-01-01

    Full Text Available 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.

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

    CERN Document Server

    Assef, R 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

    2015-01-01

    Hot Dust-Obscured Galaxies (Hot DOGs) are a population of hyper-luminous infrared galaxies identified by the WISE mission from their very red mid-IR colors, and characterized by hot dust temperatures ($T>60~\\rm K$). Several studies have shown clear evidence that the IR emission in these objects is powered by a highly dust-obscured 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 8 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 D...

  19. Cathodes incorporating thin fluoride layers for efficient injection in blue polymer light-emitting diodes

    Science.gov (United States)

    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.

  20. Photoinhibition of stem elongation by blue and red light: effects on hydraulic and cell wall properties

    Science.gov (United States)

    Kigel, J.; Cosgrove, D. J.

    1991-01-01

    The underlying mechanism of photoinhibition of stem elongation by blue (BL) and red light (RL) was studied in etiolated seedlings of pea (Pisum sativum L. cv Alaska). Brief BL irradiations resulted in fast transient inhibition of elongation, while a delayed (lag approximately 60 minutes) but prolonged inhibition was observed after brief RL. Possible changes in the hydraulic and wall properties of the growing cells during photoinhibition were examined. Cell sap osmotic pressure was unaffected by BL and RL, but both irradiations increased turgor pressure by approximately 0.05 megapascal (pressure-probe technique). Cell wall yielding was analyzed by in vivo stress relaxation (pressure-block technique). BL and RL reduced the initial rate of relaxation by 38 and 54%, while the final amount of relaxation was decreased by 48 and 10%, respectively. These results indicate that RL inhibits elongation mainly by lowering the wall 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.

  1. Female Sprague Dawley Rats Show Impaired Spatial Memory in the 8-Arm Radial Maze under Dim Blue and Red Light

    OpenAIRE

    Michael Pirchl; Georg Kemmler; Christian Humpel

    2010-01-01

    Light intensity and wavelength strongly influence mood and cognition in humans and rodent animal models. The aim of the present study was to explore if dim white (7.6–17.7 lux) , blue (1.3–2.3 lux), and red light (0.8–1.4 lux) affect spatial memory of male and female Sprague Dawley rats in the 8-arm radial maze. Our data show that spatial memory significantly improved within 5 daily learning sessions (each 5 trials) under dim white light, which was not different between male and female rats. ...

  2. Degradation and destruction of historical blue-green glass beads: a study using microspectroscopy of light transmission

    International Nuclear Information System (INIS)

    Blue-green historical beads are sometimes described as unstable because of their degradability. At present, it is not known what causes the deterioration of these beads. We explore the internal microstucture of degrading blue-green historical beads and its evolution in the process of bead deterioration. Investigating the transmittance and scattering spectra of visible and near infrared light we observe the formation of microscopic internal inhomogeneities of sizes less than 150 nm in the glass bulk, and growth of their density with an increase in the degree of bead degradation. By means of laser scanning microscopy we also observe numerous microinclusions and microcracks on the cleavage surface of a partially degraded bead. We discuss possible physical factors resulting in the destruction of the blue-green beads

  3. White emission from nano-structured top-emitting organic light-emitting diodes based on a blue emitting layer

    International Nuclear Information System (INIS)

    We demonstrated that white emission can be obtained from nano-structured top-emitting organic light-emitting diodes (TEOLEDs) based on a blue emitting layer (EML). The nano-structured TEOLEDs were fabricated on nano-patterned substrates, in which both optical micro-cavity and scattering effects occur simultaneously. Due to the combination of these two effects, the electroluminescence spectra of the nano-structured device with a blue EML exhibited not only blue but also yellow colours, which corresponded to the intrinsic emission of the EML and the resonant emission of the micro-cavity effect. Consequently, it was possible to produce white emission from nano-structured TEOLEDs without employing a multimode micro-cavity. The intrinsic emission wavelength can be varied by altering the dopant used for the EML. Furthermore, the emissive characteristics turned out to be strongly dependent on the nano-pattern sizes of the nano-structured devices. (paper)

  4. Red Light Combined with Blue Light Irradiation Regulates Proliferation and Apoptosis in Skin Keratinocytes in Combination with Low Concentrations of Curcumin.

    Directory of Open Access Journals (Sweden)

    Tianhui Niu

    Full Text Available 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.

  5. Polarization-multiplexed 2×2 phosphor-LED wireless light communication without using analog equalization and optical blue filter

    Science.gov (United States)

    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.

  6. Effect of arylamine hole-transport units on the performance of blue polyspirobifulorene light-emitting diodes

    Science.gov (United States)

    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.

  7. Photoprotection of human retinal pigment epithelium cells against blue light-induced apoptosis by melanin free radicals from Sepia officinalis

    OpenAIRE

    Seagle, Brandon-Luke L.; Gasyna, Elzbieta M.; Mieler, William F.; Norris, James R.

    2006-01-01

    Cultured retinal pigment epithelium (RPE) cells can phagocytize large foreign particles. Heterogeneous melanin aggregates from Sepia officinalis, a species of cuttlefish, were fed to cultured human RPE cells to produce cells laden with Sepia melanin. Blue light-induced apoptosis (BLIA) assays were performed by flow cytometry on parallel cultures consisting of RPE cells isolated from independent eyes and evenly divided into two cultures, one fed Sepia melanin and one containing only native mel...

  8. High-efficiency pyrene-based blue light emitting diodes: Aggregation suppression using a calixarene 3D-scaffold

    KAUST Repository

    Chan, Khaileok

    2012-01-01

    An efficient blue light emitting diode based on solution processable pyrene-1,3-alt-calix[4]arene is demonstrated, providing a record current efficiency of 10.5 cd A -1 in a simple non-doped OLED configuration. Complete suppression of pyrene aggregation in the solid state is achieved by controlling chromophore dispersion using the 1,3-alt-calix[4]arene scaffold. © 2012 The Royal Society of Chemistry.

  9. The Subcellular Localization and Blue-Light-Induced Movement of Phototropin 1-GFP in Etiolated Seedlings of Arabidopsis thaliana

    Institute of Scientific and Technical Information of China (English)

    Ying-Lang Wan; William Eisinger; David Ehrhardt; Ulrich Kubitscheck; Frantisek Baluska; Winslow Briggs

    2008-01-01

    Phototropin 1 (phot1) is a photoreceptor for phototropism, chloroplast movement, stomatal opening, leaf expansion, and solar tracking in response to blue light. Following earlier work with PHOT1::GFP (Sakamoto and Briggs,2002), we investigated the pattern of cellular and subcellular localization of phot1 in 3-4 d old etiolated seedlings of Arabidopsis thalinana. As expressed from native upstream sequences, the PHOT1::GFP fusion protein is expressed strongly in the abaxial tissues of the cotyledons and in the elongating regions of the hypocotyl. It is moderately expressed in the shoot/root transition zone and in cells near the root apex. A fluorescence signal is undetectable in the root epidermis, root cap, and root apical meristem itself. The plasma membranes of mesophyll cells near the cotyledon margin appear labeled uniformly but cross-walls created by recent cell divisions are more strongly labeled. The pattern of labeling of individual cell types varies with cell type and developmental stage. Blue-light treatment causes PHOT1::GFP, initially relatively evenly distributed at the plasma membrane, to become reorganized into a distinct mosaic with strongly labeled punctate areas and other areas completely devoid of fluorescence-a phenomenon best observed in cortical cells in the hypocotyl elongation region. Concomitant with or following this reorganization, PHOT1::GFP moves into the cytoplasm in all cell types investigated except for guard cells. It disappears from the cytoplasm by an unidentified mechanism after several hours in darkness. Neither its appearance in the cytoplasm nor its eventual disappearance in darkness is prevented by the translation inhibitor cycloheximide, although the latter process is retarded. We hypothesize that blue-light-induced phot1 relocalization modulates blue-light-activated signal transduction.

  10. In vitro and in vivo antimicrobial activity of combined therapy of silver nanoparticles and visible blue light against Pseudomonas aeruginosa

    OpenAIRE

    Nour El Din S; El-Tayeb TA; Abou-Aisha K; El-Azizi M

    2016-01-01

    Suzanne Nour El Din,1 Tarek A El-Tayeb,2 Khaled Abou-Aisha,1 Mohamed El-Azizi1 1Department of Microbiology, Immunology and Biotechnology, Faculty of Pharmacy and Biotechnology, German University in Cairo, 2National Institute for Laser Enhanced Sciences, Cairo University, Cairo, Egypt Abstract: 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 ...

  11. Low-intensity blue-enriched white light (750 lux and standard bright light (10 000 lux are equally effective in treating SAD. A randomized controlled study

    Directory of Open Access Journals (Sweden)

    Bos Elske H

    2011-01-01

    Full Text Available Abstract Background Photoreceptor cells containing melanopsin play a role in the phase-shifting effects of short-wavelength light. In a previous study, we compared the standard light treatment (SLT of SAD with treatment using short-wavelength blue-enriched white light (BLT. Both treatments used the same illuminance (10 000 lux and were equally highly effective. It is still possible, however, that neither the newly-discovered photoreceptor cells, nor the biological clock play a major role in the therapeutic effects of light on SAD. Alternatively, these effects may at least be partly mediated by these receptor cells, which may have become saturated as a result of the high illuminances used in the therapy. This randomized controlled study compares the effects of low-intensity BLT to those of high-intensity SLT. Method In a 22-day design, 22 patients suffering from a major depression with a seasonal pattern (SAD were given light treatment (10 000 lux for two weeks on workdays. Subjects were randomly assigned to either of the two conditions, with gender and age evenly distributed over the groups. Light treatment either consisted of 30 minutes SLT (5000°K with the EnergyLight® (Philips, Consumer Lifestyle with a vertical illuminance of 10 000 lux at eye position or BLT (17 000°K with a vertical illuminance of 750 lux using a prototype of the EnergyLight® which emitted a higher proportion of short-wavelengths. All participants completed questionnaires concerning mood, activation and sleep quality on a daily basis. Mood and energy levels were also assessed on a weekly basis by means of the SIGH-SAD and other assessment tools. Results On day 22, SIGH-SAD ratings were significantly lower than on day 1 (SLT 65.2% and BLT 76.4%. On the basis of all assessments no statistically significant differences were found between the two conditions. Conclusion With sample size being small, conclusions can only be preliminary. Both treatment conditions were found

  12. Out of the Lab and into the Bathroom: Evening Short-Term Exposure to Conventional Light Suppresses Melatonin and Increases Alertness Perception

    Directory of Open Access Journals (Sweden)

    Heinz Schoepp

    2013-01-01

    Full Text Available Life in 24-h society relies on the use of artificial light at night that might disrupt synchronization of the endogenous circadian timing system to the solar day. This could have a negative impact on sleep–wake patterns and psychiatric symptoms. The aim of the study was to investigate the influence of evening light emitted by domestic and work place lamps in a naturalistic setting on melatonin levels and alertness in humans. Healthy subjects (6 male, 3 female, 22–33 years were exposed to constant dim light (<10 lx for six evenings from 7:00 p.m. to midnight. On evenings 2 through 6, 1 h before habitual bedtime, they were also exposed to light emitted by 5 different conventional lamps for 30 min. Exposure to yellow light did not alter the increase of melatonin in saliva compared to dim light baseline during (38 ± 27 pg/mL vs. 39 ± 23 pg/mL and after light exposure (39 ± 22 pg/mL vs. 44 ± 26 pg/mL. In contrast, lighting conditions including blue components reduced melatonin increase significantly both during (office daylight white: 25 ± 16 pg/mL, bathroom daylight white: 24 ± 10 pg/mL, Planon warm white: 26 ± 14 pg/mL, hall daylight white: 22 ± 14 pg/mL and after light exposure (office daylight white: 25 ± 15 pg/mL, bathroom daylight white: 23 ± 9 pg/mL, Planon warm white: 24 ± 13 pg/mL, hall daylight white: 22 ± 26 pg/mL. Subjective alertness was significantly increased after exposure to three of the lighting conditions which included blue spectral components in their spectra. Evening exposure to conventional lamps in an everyday setting influences melatonin excretion and alertness perception within 30 min.

  13. Giantically blue-shifted visible light in femtosecond mid-IR filament in fluorides

    CERN Document Server

    Dormidonov, A E; Chekalin, S V; Kandidov, V P

    2015-01-01

    A giant blue shift of an isolated visible band of supercontinuum was discovered and studied in the single filament regime of Mid-IR femtosecond laser pulse at powers slightly exceeding critical power for self-focusing in fluorides.

  14. Inhibition of blue-light-dependent binding of 14-3-3 proteins to phototropins by hydrogen peroxide

    Institute of Scientific and Technical Information of China (English)

    ZHANG Xiao; SHIMAZAKI Kenichiro

    2005-01-01

    @@ Phototropins, following the discovery of phytochromes[1,2] and cryptochromes[3,4], are the most recently characterized blue-light (BL) receptors in plants. The N- terminal regions of the proteins contain two light oxygen and voltage (LOV)――LOV1 and LOV2, which belong to PAS domain involved in protein-protein interaction and ligand binding, possessing non-covalent binding sites for the chromophore FMN[5]. The C-terminal regions contain Ser/Thr kinase domains[6].

  15. Polarization-matched quaternary superlattice electron blocking layer in blue InGaN light-emitting diodes

    Science.gov (United States)

    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.

  16. All solution processed blue multi-layer light emitting diodes realized by thermal layer stabilization and orthogonal solvent processing

    Science.gov (United States)

    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.

  17. Blue-light mediated accumulation of nuclear-encoded transcripts coding for proteins of the thylakoid membrane is absent in the phytochrome-deficient aurea mutant of tomato

    International Nuclear Information System (INIS)

    Polyclonal antibodies against pea phytochrome detect 2 protein bands (about 116 and 120 kDa) on blots of crude protein extracts and protein of microsomal preparations of dark-grown tomato seedlings. Both protein bands are undetectable in Western blots of the aurea mutant extracts. Neither protein band is detectable after isogenic wild-type seedlings are illuminated with 3 h of red light, either in the crude extract or in the membrane fraction of the irradiated seedlings; this result is consistent with the hypothesis that both bands are phytochrome. When dark-grown wild-type seedlings are illuminated with 3 h of red light or blue light against a red light background, the transcript levels for chlorophyll a/b-binding proteins of photosystem I and II, plastocyanin, and the subunit II of photosystem I increase. In all cases, the same fluence rate of blue light is much more effective than red light alone, a result that indicates the involvement of a blue/UV-A light photoreceptor in addition to the involvement of the far-red-absorbing form of phytochrome, Pfr. The aurea mutant responds neither to red light nor to blue light. Thus, no Pfr-independent induction of the four transcripts by a blue/UV-A light photoreceptor can be measured in the aurea mutant

  18. A comparative study of blue, green and yellow light emitting diode structures grown by metal organic chemical vapor deposition

    Science.gov (United States)

    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.

  19. Carbazolyldibenzofuran-type high-triplet-energy bipolar host material for blue phosphorescent organic light-emitting diodes

    International Nuclear Information System (INIS)

    A high-triplet-energy material, 9′-(4,4′-(phenylphosphoryl)bis(dibenzo[b,d]furan-6,2-diyl)) bis(9H-carbazole) (44DFCzPO), was synthesized as a bipolar host material for blue phosphorescent organic light-emitting diodes (PHOLEDs). 44DFCzPO was synthesized by the selective lithiation of the 4-position of a carbazole-modified dibenzofuran, followed by phosphorylation. 44DFCzPO showed a high triplet energy of 2.91 eV for energy transfer to a blue phosphorescent dopant, and bipolar charge transport properties for balanced hole and electron density in the emitting layer. A high quantum efficiency of 16.7% at a low doping concentration of 3% was obtained using 44DFCzPO as the host in blue PHOLEDs. -- Highlights: • High quantum efficiency and stable film morphology up to 110 °C. • High triplet energy of 2.91 eV for energy transfer to blue dopant. • Carbazolyldibenzofuran type high triplet energy host material

  20. 红蓝光照射治疗痤疮110例%Red Light and Blue Light Therapy in Treating Patients with Ache: 110 Cases

    Institute of Scientific and Technical Information of China (English)

    邵燕磊; 王蕾

    2012-01-01

    Objective To investigate the clinical efficacy and safety of the red light and blue light therapy on 110 cases of acne patients. Methods Subjects were treated by the red light and blue light therapy alternatively with a total of eight serial biweekly treatment sessions. They were assessed and compared with the reduced rates of acne lesions in patients before and after treatment. Results The total effective rate was 83.09%. The average reduced rates of the non-inflammatory lesions and inflammatory lesions were 52.36% and 69.47% respectively (P<0.05). After three months follow-up, the total effective rate had no significant statistical difference compare to the end of treatment sessions. Conclusion The treatment of acne patients with the red light and blue light is effective in acne. And it has low recurrence rate and fewer side effects.%目的 观察红蓝光照射治疗痤疮的临床疗效和安全性.方法 联合红蓝光治疗110例痤疮患者,每周2次,共8次,计数患者炎性病损及非炎性病损及皮损总数来比较改善率.结果 治疗结束时有效率为83.09%;非炎性皮损及炎性皮损平均改善率分别为52.36%和69.47%,P<0.05;随访3个月,有效率与治疗结束时比较差异无统计学意义.结论 红蓝光治疗痤疮疗效显著、复发率低、不良反应少.

  1. Theoretical study on alkyne-linked carbazole polymers for blue-light multifunctional materials

    International Nuclear Information System (INIS)

    This paper studied poly[(3,6-di-tert-butyl-N-hexadecyl-1,8-carbazolylene) butadiynylene] (P1), butadiynylene-linked poly (3,6-carbazole) (P2) and butadiynylene-linked poly (2,7-carbazole) (P3) through the theoretical measurements with Gaussian 03 program package. To investigate the relationship between structures and properties of these multifunctional electroluminescent materials, their geometrical structures of ground and excited-states were optimized by B3LYP/6-31G (d) and CIS/6-31G (d) methods, respectively. The lowest excitation energies (Eg's), and the maximum absorption and emission wavelengths of these polymers were calculated by time-dependent density functional theory methods (TD-DFT). The important parameters for luminescent materials were also predicated including the ionization potentials (Ip's) and electron affinities (Ea's). The calculated results show that the highest-occupied molecular orbital (HOMO) energies lift about 0.27-0.49 eV compared to N,N'-bis(naphthyl)-N,N'-diphenyl-1,1'-biphenyl-4,4'-diamine (NPB), suggesting the significant improved hole-accepting and transporting abilities. In addition, substitution of alkyne for carbazole resulted in a narrow band gap and a red shift of both the absorption and emission peaks. Through above calculations, it is evidenced that these polymers can be considered as candidates for excellent OLEDs with good hole-creating abilities and high blue-light emission. - Highlights: → We studied poly [(3,6-di-tert-butyl-N-hexadecyl-1,8-carbazolylene) butadiynylene] by theoretical method. → The geometrical structures of ground and excited-states had been optimized by B3LYP/6-31G (d) and CIS/6-31G (d). → The relationship between structures and properties of these multifunctional electroluminescent materials had been investigated. → These molecules are excellent candidates for multifunctional OLED materials. → The substitution of alkyne for carbazole results in a narrow band gap and a red shift of both the

  2. Influence of dark blue spectrum light on degree of freshness of boiled sausages at storage

    International Nuclear Information System (INIS)

    Control samples of cooked sausages (CCS) with a natural casing were placed into a refrigerated counter (at temperature 0-4 deg C, relative humidity of 75%). Pilot samples of CS (PCS) were done into a refrigerated counter under blue light (BL) illumination of intensity of 35 micro watt/square centimeter and of a capacity of 15 J/sec. After 10 days of storage CCS had an unpleasant taste and smell, gray and green color and PCS were within normal limits. After 3, 5 and 10 days of storage a peroxide value of fat increased up to 6.8, 9.8 and 18.7 milli mole 1/2 O/kg (CCS) and up to 6.0, 7.0 and 9,0 mmole 1/2 O/kg (PCS) respectively. After 3 days of storage the acid number of fat of CCS was higher by 16% than the one of PCS. After 5 and 10 days of storage the acid number of CCS was at 1.6 and 2.0 mg of KOH, the one of PCS was at 1.3 and 1.5 mg KOH respectively. BL significantly reduced a concentration of oxyacids (by 76%) up to the end of storage. After 3 and 5 days of storage the CCS had a pH of 5.4 and of 5.8 at a normal rate of 5.0-6.8 for a fresh product. After 10 days the parameter was 6.9, while the one of PCS was recorded at 6.5. At the end of storage CCS did not requirements to the standards of microbiological purity and PCS had no such abnormalities. It has been concluded that the BL does not influence on temperature inside the product and reduces the intensity of hydrolytic, oxidative processes in fat. It has got highly penetrating and powerful bactericidal action, does not reduce a nutritional value and can be recommended to extend a shelf life of CS

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

    Science.gov (United States)

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

    2015-05-01

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

  4. High-efficiency blue multilayer polymer light-emitting diode based on poly(9,9-dioctylfluorene)

    Science.gov (United States)

    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%.

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

    Science.gov (United States)

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

    2008-04-01

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

  6. Blue emitting fluorophores of phenyleneethynylenes substituted by diphenylethenyl terminal groups for organic light-emitting diodes

    International Nuclear Information System (INIS)

    Phenyleneethynylene motifs substituted by diphenylethenyl groups at both ends were prepared successfully by use of double elimination protocol of β-substituted sulfones for introducing phenyleneethynylene arrays followed by Wittig-Horner reaction for introducing diphenylethenyl moiety. The hybrid blue fluorophores exhibited strong emission even in the solid-state films (ΦF ≥ 0.60) while, in CHCl3 solution, incorporation of substituents on the central phenylene unit significantly enhanced emission efficiency up to ΦF = 0.57. The OLED devices with use of these blue fluorophores as an emitting material provided maximum external quantum efficiency of ηext = 2.4%

  7. Morphological, Photosynthetic, and Physiological Responses of Rapeseed Leaf to Different Combinations of Red and Blue Lights at the Rosette Stage.

    Science.gov (United States)

    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

  8. DNA damage in lung after oral exposure to diesel exhaust particles in Big Blue (R) rats

    DEFF Research Database (Denmark)

    Müller, Anne Kirstine; Farombi, E.O.; Møller, P.;

    2004-01-01

    . Lung tissue is a target organ for DEP induced cancer following inhalation. Recent studies have provided evidence that the lung is also a target organ for DNA damage and cancer after oral exposure to other complex mixtures of PAHs. The genotoxic effect of oral administration of DEP was investigated, in...... endonuclease III and fapyguanine glycosylase (FPG) sensitive sites increased at the intermediate dose levels. The induction of DNA damage by DEP exposure did not increase the expression of the repair genes OGG1 and ERCC1 at the mRNA level. The present study indicates that the lung is a target organ for primary...... DNA damage following oral exposure to DEP. DNA damage was induced following exposure to relatively low levels of DEP, but under the conditions used in the present experiment DNA damage did not result in an increased mutation rate....

  9. DNA damage in lung after oral exposure to diesel exhaust particles in Big Blue (R) rats

    DEFF Research Database (Denmark)

    Müller, Anne Kirstine; Farombi, E.O.; Møller, P.; Autrup, H.N.; Vogel, U.; Wallin, H.; Dragsted, Lars Ove; Loft, S.; Binderup, Mona-Lise

    . Lung tissue is a target organ for DEP induced cancer following inhalation. Recent studies have provided evidence that the lung is also a target organ for DNA damage and cancer after oral exposure to other complex mixtures of PAHs. The genotoxic effect of oral administration of DEP was investigated, in...... endonuclease III and fapyguanine glycosylase (FPG) sensitive sites increased at the intermediate dose levels. The induction of DNA damage by DEP exposure did not increase the expression of the repair genes OGG1 and ERCC1 at the mRNA level. The present study indicates that the lung is a target organ for primary...... DNA damage following oral exposure to DEP. DNA damage was induced following exposure to relatively low levels of DEP, but under the conditions used in the present experiment DNA damage did not result in an increased mutation rate....

  10. Non-invasive plant growth measurements for detection of blue-light dose response of stem elongation in Chrysanthemum morifolium

    DEFF Research Database (Denmark)

    Kjær, Katrine Heinsvig

    2012-01-01

    Quantitative and qualitative imaging of plant growth and development in response to environmental factors under greenhouse conditions visualises plant performance on-site and may increase our knowledge of how rapid plants change their growth pattern in relation to environmental stimuli. In the...... present study a non-invasive plant growth sensor (PlantEye, Phenospex B.V, Heerlen, NL) was tested in analysing changes in diurnal stem elongation patterns and plant height in response to the spectral quality of the light environment. Plants were grown in four different LED supplemental lighting...... treatments with 0%, 12.5%, 18.5% and 22.5% blue light under greenhouse conditions in winter (18 h day/4 h night). The non-invasive measurements were carried out automatically every four hour with three repetitions, and supported by manual measurements of plant height every third day. A strong linear relation...

  11. Light pollution modelling the UK Highways Agency new environmental policy, inc. astronomical impact of blue-rich LED luminaires.

    Science.gov (United States)

    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.

  12. Generation of high-power blue light in periodically poled LiNbO3

    NARCIS (Netherlands)

    Ross, Graeme W.; Pollnau, Markus; Smith, Peter G.R.; Clarkson, W. Andrew; Britton, Paul E.; Hanna, David C.

    1998-01-01

    We report the generation of 450-mW average blue (473-nm) power by frequency doubling of a diode-pumped 946-nm Nd:YAG laser. We achieved pulsed operation at a high repetition rate (~160 kHz) by driving the relaxation oscillations of the laser. A 40% conversion efficiency to the second harmonic was ob

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

    DEFF Research Database (Denmark)

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

    2000-01-01

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

  14. Tunable ultraviolet and blue light generation from Nd:YAB random laser bolstered by second-order nonlinear processes

    Science.gov (United States)

    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.

  15. Optical Properties of Blue-Light-Emitting (Ca,Sr)Mg2Si3O9:Eu2+ Phosphor

    Science.gov (United States)

    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.

  16. Efficient blue and white polymer light emitting diodes based on a well charge balanced, core modified polyfluorene derivative.

    Science.gov (United States)

    Das, Dipjyoti; Gopikrishna, Peddaboodi; Singh, Ashish; Dey, Anamika; Iyer, Parameswar Krishnan

    2016-03-14

    Fabrication of efficient blue and white polymer light-emitting diodes (PLEDs) using a well charge balanced, core modified polyfluorene derivative, poly[2,7-(9,9'-dioctylfluorene)-co-N-phenyl-1,8-naphthalimide (99:01)] (PFONPN01), is presented. The excellent film forming properties as observed from the morphological study and the enhanced electron transport properties due to the inclusion of the NPN unit in the PFO main chain resulted in improved device properties. Bright blue light was observed from single layer PLEDs with PFONPN01 as an emissive layer (EML) as well as from double layer PLEDs using tris-(8-hydroxyquinoline) aluminum (Alq3) as an electron transporting layer (ETL) and LiF/Al as a cathode. The effect of ETL thickness on the device performance was studied by varying the Alq3 thickness (5 nm, 10 nm and 20 nm) and the device with an ETL thickness of 20 nm was found to exhibit the maximum brightness value of 11 662 cd m(-2) with a maximum luminous efficiency of 4.87 cd A(-1). Further, by using this highly electroluminescent blue PFONPN01 as a host and a narrow band gap, yellow emitting small molecule, dithiophene benzothiadiazole (DBT), as a guest at three different concentrations (0.2%, 0.4% and 0.6%), WPLEDs with the ITO/PEDOT:PSS/emissive layer/Alq3(20 nm)/LiF/Al configuration were fabricated and maximum brightness values of 8025 cd m(-2), 9565 cd m(-2) and 10 180 cd m(-2) were achieved respectively. 0.4% DBT in PFONPN01 was found to give white light with Commission International de l'Echairage (CIE) coordinates of (0.31, 0.38), a maximum luminous efficiency of 6.54 cd A(-1) and a color-rendering index (CRI) value of 70. PMID:26899815

  17. The Trichoderma atroviride cryptochrome/photolyase genes regulate the expression of blr1-independent genes both in red and blue light.

    Science.gov (United States)

    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

  18. Blue organic light-emitting diode as the electro-optical conversion device for high-speed switching applications

    International Nuclear Information System (INIS)

    Luminance of about 40 mW cm-2 with an emission peak at about 435 nm and the optical pulses of 100 MHz have been obtained from a blue organic light-emitting diode (OLED) based on the N,N'-di(naphtalen-1-yl)-N,N'- diphenylbenzidine emissive layer with the active area of 0.01 mm2. The performance of modulation speed was improved significantly by applying the positive offset voltage in the range of lower voltages. We demonstrate that the OLEDs can be applied to the electro-optical conversion device for high-speed switching applications. (author)

  19. Cyclodextrin-Isolated Alkynylpyrenes as UV-Stable and Blue-Light-Emitting Molecules Even in Condensed States.

    Science.gov (United States)

    Inouye, Masahiko; Yoshizawa, Atsushi; Shibata, Mari; Yonenaga, Yuki; Fujimoto, Kazuhisa; Sakata, Takuma; Matsumoto, Shinya; Shiro, Motoo

    2016-05-01

    Encapsulation of highly emissive alkynylpyrenes with permethylated α-cyclodextrin (PM-α-CD) followed by capping reaction yielded alkynylpyrene-based [3]rotaxanes. The [3]rotaxane emitted only blue light of monomeric pyrene under various circumstances such as lipophilic, hydrophilic, and even condensed states and exhibited extremely high stability for UV irradiation. These properties would result because PM-α-CD, like bulletproof glass, protected the alkynylpyrene core from the attack of another excited alkynylpyrene and singlet oxygen generated by the energy transfer from the excited alkynylpyrene. PMID:27058597

  20. Thermal dependence of time-resolved blue light stimulated luminescence in α-Al2O3:C

    DEFF Research Database (Denmark)

    Pagonis, Vasilis; Ankjærgaard, Christina; Jain, Mayank;

    2013-01-01

    This paper presents time-resolved optically stimulated luminescence (TR-OSL) experiments in the important dosimetric material Al2O 3:C. During these experiments short pulses (0.5 s) of light from blue LEDs (470 nm) are followed by relaxation periods (2.5 s) of the charge carriers at different......-dependent phosphorescence signal, the delayed-OSL described previously for this material. The temperature dependent luminescence lifetimes obtained from analysis of the optical stimulation period are identical to those obtained from the corresponding relaxation period. However, the values of these luminescence lifetimes...

  1. In vitro and in vivo antimicrobial activity of combined therapy of silver nanoparticles and visible blue light against Pseudomonas aeruginosa

    Directory of Open Access Journals (Sweden)

    Nour El Din S

    2016-04-01

    Full Text Available Suzanne Nour El Din,1 Tarek A El-Tayeb,2 Khaled Abou-Aisha,1 Mohamed El-Azizi1 1Department of Microbiology, Immunology and Biotechnology, Faculty of Pharmacy and Biotechnology, German University in Cairo, 2National Institute for Laser Enhanced Sciences, Cairo University, Cairo, Egypt Abstract: 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 (1×105 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 activity of AgNPs and visible blue light was significantly enhanced (P<0.001 when both agents were combined compared to each agent alone when AgNPs were tested at MIC, 1/2, or 1/4 MIC. Transmission electron microscope showed significant damage to the cells that were treated with the combined therapy compared to other cells that received either the AgNPs or blue light. In addition, the combined treatment significantly (P<0.001 inhibited biofilm formation by P. aeruginosa on gelatin discs compared to each agent individually. Finally, the combined therapy effectively treated a horse suffering from a chronic wound caused by mixed

  2. High-brightness semipolar (2021¯) blue InGaN/GaN superluminescent diodes for droop-free solid-state lighting and visible-light communications.

    Science.gov (United States)

    Shen, Chao; Ng, Tien Khee; Leonard, John T; Pourhashemi, Arash; Nakamura, Shuji; DenBaars, Steven P; Speck, James S; Alyamani, Ahmed Y; El-Desouki, Munir M; Ooi, Boon S

    2016-06-01

    A high-brightness, droop-free, and speckle-free InGaN/GaN quantum well blue superluminescent diode (SLD) was demonstrated on a semipolar (2021¯) GaN substrate. The 447-nm emitting SLD has a broad spectral linewidth of 6.3 nm at an optical power of 123 mW. A peak optical power of 256 mW was achieved at 700 mA CW injection current. By combining YAG:Ce phosphor, SLD-generated white light shows a color-rendering index (CRI) of 68.9 and a correlated color temperature (CCT) of 4340 K. The measured frequency response of the SLD revealed a -3  dB bandwidth of 560 MHz, thus demonstrating the feasibility of the device for both solid-state lighting (SSL) and visible-light communication (VLC) applications. PMID:27244426

  3. Efficient triplet exciton confinement of white organic light-emitting diodes using a heavily doped phosphorescent blue emitter

    International Nuclear Information System (INIS)

    We demonstrated efficient white electrophosphorescence with a heavily doped phosphorescent blue emitter and a triplet exciton blocking layer (TEBL) inserted between the hole transporting layer (HTL) and the emitting layer (EML). We fabricated white organic light-emitting diodes (WOLEDs) (devices A, B, C, and D) using a phosphorescent red emitter; bis(2-phenylquinolinato)-acetylacetonate iridium III (Ir(pq)2acac) doped in the host material; N,N'-dicarbazolyl-3,5-benzene (mCP) as the red EML and the phosphorescent blue emitter; bis(3,5-Difluoro-2-(2-pyridyl)phenyl-(2-carboxypyridyl) iridium III (FIrpic) doped in the host material; p-bis(triphenylsilyly)benzene (UGH2) as the blue EML. The properties of device B, which demonstrate a maximum luminous efficiency and external quantum efficiency of 26.83 cd/A and 14.0%, respectively, were found to be superior to the other WOLED devices. It also showed white emission with CIEx,y coordinates of (x = 0.35, y = 0.35) at 8 V. Device D, which has a layer of P-type 4,4',4''-tri(N-carbazolyl)triphenylamine (TCTA) material between the HTL and TEBL, was compared with device A to determine the 430 nm emission peak.

  4. Observation of intermediate bands in Eu3+ doped YPO4 host: Li+ ion effect and blue to pink light emitter

    Directory of Open Access Journals (Sweden)

    Abdul Kareem Parchur

    2012-09-01

    Full Text Available This article explores the tuning of blue to pink colour generation from Li+ ion co-doped YPO4:5Eu nanoparticles prepared by polyol method at ∼100-120 °C with ethylene glycol (EG as a capping agent. Interaction of EG molecules capped on the surface of the nanoparticles and/or created oxygen vacancies induces formation of intermediate/mid gap bands in the host structure, which is supported by UV-Visible absorption data. Strong blue and pink colors can be observed in the cases of as-prepared and 500 °C annealed samples, respectively. Co-doping of Li+ enhances the emission intensities of intermediate band as well as Eu3+. On annealing as-prepared sample to 500 °C, the intermediate band emission intensity decreases, whereas Eu3+ emission intensity increases suggesting increase of extent of energy transfer from the intermediate band to Eu3+ on annealing. Emission intensity ratio of electric to magnetic dipole transitions of Eu3+ can be varied by changing excitation wavelength. The X-ray photoelectron spectroscopy (XPS study of as-prepared samples confirms the presence of oxygen vacancies and Eu3+ but absence of Eu2+. Dispersed particles in ethanol and polymer film show the strong blue color, suggesting that these materials will be useful as probes in life science and also in light emitting device applications.

  5. Strong blue and white photoluminescence emission of BaZrO{sub 3} undoped and lanthanide doped phosphor for light emitting diodes application

    Energy Technology Data Exchange (ETDEWEB)

    Romero, V.H. [Centro de Investigaciones en Optica, A. P. 1-948, Leon Gto., 37160 (Mexico); De la Rosa, E., E-mail: elder@cio.mx [Centro de Investigaciones en Optica, A. P. 1-948, Leon Gto., 37160 (Mexico); Salas, P. [Centro de Fisica Aplicada y Tecnologia Avanzada, Universidad Nacional Autonoma de Mexico, A.P. 1-1010, Queretaro, Qro. 76000 (Mexico); Velazquez-Salazar, J.J. [Department of Physics and Astronomy, The University of Texas at San Antonio One UTSA Circle, San Antonio TX 78249 (United States)

    2012-12-15

    In this paper, we report the obtained strong broadband blue photoluminescence (PL) emission centered at 427 nm for undoped BaZrO{sub 3} observed after 266 nm excitation of submicron crystals prepared by hydrothermal/calcinations method. This emission is enhanced with the introduction of Tm{sup 3+} ions and is stronger than the characteristic PL blue emission of such lanthanide. The proposed mechanism of relaxation for host lattice emission is based on the presence of oxygen vacancies produced during the synthesis process and the charge compensation due to the difference in the electron valence between dopant and substituted ion in the host. Brilliant white light emission with a color coordinate of (x=0.29, y=0.32) was observed by combining the blue PL emission from the host with the green and red PL emission from Tb{sup 3+} and Eu{sup 3+} ions, respectively. The color coordinate can be tuned by changing the ratio between blue, green and red band by changing the concentration of lanthanides. - Graphical abstract: Strong blue emission from undoped BaZrO{sub 3} phosphor and white light emission by doping with Tb{sup 3+} (green) and Eu{sup 3+} (red) after 266 nm excitation. Highlights: Black-Right-Pointing-Pointer Blue emission from BaZrO{sub 3} phosphor. Black-Right-Pointing-Pointer Blue emission enhanced with Tm{sup 3+}. Black-Right-Pointing-Pointer White light from BaZrO{sup 3+} phosphor.

  6. Organic Fluorescent Dyes Supported on Activated Boron Nitride: A Promising Blue Light Excited Phosphors for High-Performance White Light-Emitting Diodes

    Science.gov (United States)

    Li, Jie; Lin, Jing; Huang, Yang; Xu, Xuewen; Liu, Zhenya; Xue, Yanming; Ding, Xiaoxia; Luo, Han; Jin, Peng; Zhang, Jun; Zou, Jin; Tang, Chengchun

    2015-02-01

    We report an effective and rare-earth free light conversion material synthesized via a facile fabrication route, in which organic fluorescent dyes, i.e. Rhodamine B (RhB) and fluorescein isothiocyanate (FITC) are embedded into activated boron nitride (αBN) to form a composite phosphor. The composite phosphor shows highly efficient Förster resonance energy transfer and greatly improved thermal stability, and can emit at broad visible wavelengths of 500-650 nm under the 466 nm blue-light excitation. By packaging of the composite phosphors and a blue light-emitting diode (LED) chip with transparent epoxy resin, white LED with excellent thermal conductivity, current stability and optical performance can be realized, i.e. a thermal conductivity of 0.36 W/mk, a Commission Internationale de 1'Eclairage color coordinates of (0.32, 0.34), and a luminous efficiency of 21.6 lm.W-1. Our research opens the door toward to the practical long-life organic fluorescent dyes-based white LEDs.

  7. Dose response of hydrazine - Deproteinated tooth enamel under blue light stimulation

    Energy Technology Data Exchange (ETDEWEB)

    Yuece, Ulkue Rabia, E-mail: ulkuyuce@hotmail.co [Ankara University, Faculty of Engineering, Department of Engineering Physics, 06100, Tandogan - Ankara (Turkey); Meric, Niyazi, E-mail: meric@ankara.edu.t [Ankara University, Faculty of Engineering, Department of Engineering Physics, 06100, Tandogan - Ankara (Turkey); Atakol, Orhan, E-mail: atakol@science.ankara.edu.t [Ankara University, Science Faculty, Department of Chemistry, 06100, Tandogan - Ankara (Turkey); Yasar, Fusun, E-mail: ab121310@adalet.gov.t [Council of Forensic Medicine, Ankara Branch, Ankara (Turkey)

    2010-08-15

    The beta dose response and Optically Stimulated Luminescence (OSL) signal stability characteristics of human tooth enamel deproteinated by hydrazine reagent under blue photon stimulation are reported. Removal of the protein organic component of tooth enamel resulted in a higher OSL sensitivity and slower fading of OSL signals. The effect of chemical sample preparation on the enamel sample sensitivity is discussed and further steps to make this deproteinization treatment suitable for in vitro dose reconstruction studies are suggested.

  8. A blue-emitting Sc silicate phosphor for ultraviolet excited light-emitting diodes.

    Science.gov (United States)

    Wang, Qian; Zhu, Ge; Xin, Shuangyu; Ding, Xin; Xu, Ju; Wang, Yuansheng; Wang, Yuhua

    2015-11-01

    A blue-emitting phosphor BaSc2Si3O10:Eu(2+) was synthesized using the conventional solid-state reaction. The crystallographic occupancy of Eu(2+) in the BaSc2Si3O10 matrix was studied based on the Rietveld refinement results and the photoluminescence properties. BaSc2Si3O10 exhibits blue emission ascribed to (3)T2-(1)A1 and (3)T1-(1)A1 charge transfer of SiO4(4-) excited by 360 nm. All the phosphors of BaSc2Si3O10:Eu(2+) exhibit strong broad absorption bands in the near ultraviolet range, and give abnormal blue emission upon 330 nm excitation. The abnormal phenomenon was explored in detail through many pieces of experimental evidence. The concentration of Eu(2+) is optimized to be 3 mol% according to emission intensity and the quenching mechanism is verified to be a quadrupole-quadrupole interaction. The CIE coordinates of BaSc2Si3O10:0.03Eu(2+) are calculated to be (0.15, 0.05) and BaSc2Si3O10:0.03Eu(2+) shows similar thermal stability to commercial BaMgAl10O17:Eu(2+). PMID:26242881

  9. Natural Light Exposure, Sleep and Depression among Day Workers and Shiftworkers at Arctic and Equatorial Latitudes

    OpenAIRE

    Marqueze, EC; Vasconcelos, S.; Garefelt, J; Skene, DJ; Moreno, CR; A. Lowden

    2015-01-01

    OBJECTIVES: This study aimed to investigate the relationship between individual natural light exposure, sleep need, and depression at two latitudes, one extreme with a few hours of light per day during winter, and the other with equal hours of light and darkness throughout the year. METHODS: This cross-sectional study included a sample of Brazilian workers (Equatorial, n = 488 workers) and a Swedish sample (Arctic, n = 1,273). RESULTS: The reported mean total natural light exposure per 4-week...

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

    Directory of Open Access Journals (Sweden)

    Kristin Collier Valle

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

  11. Visible-light photocatalytic degradation of methylene blue with laser-induced Ag/ZnO nanoparticles

    International Nuclear Information System (INIS)

    The preparation of Ag doped ZnO nanoparticles conducted through the method of laser-induction is presented in this work. The Ag/ZnO nanoparticles attained from various weight percentages of added AgNO3 relative to ZnO were applied under visible-light irradiation for evaluating the heterogeneous photocatalytic degradations of methylene blue (MB) solutions. It was shown that the catalytic behavior of Ag/ZnO nanoparticles in the visible-light range is notably improved through the Ag deposition onto ZnO nanoparticles by the method of laser-induction with a maximum effectiveness of 92% degradation. The properties of the nanoparticles were characterized by the employments of UV-vis spectroscopy (UV-vis), X-ray diffraction (XRD), transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDX), and selected-area electron diffraction (SAED).

  12. Growth and Properties of Blue and Amber Complex Light Emitting InGaN/GaN Multi-Quantum Wells

    Institute of Scientific and Technical Information of China (English)

    XIE Zi-Li; HAN Ping; SHI Yi; ZHENG You-Dou; ZHANG Rong; LIU Bin; XIU Xiang-Qian; SU Hui; LI Yi; HUA Xue-Mei; ZHAO Hong; CHEN Peng

    2011-01-01

    @@ Blue-red complex light emitting InGaN/GaN multi-quantum well(MQW) structures are fabricated by metal organic chemical vapor deposition(MOCVD).The structures are grown on a 2-inch diameter(0001) oriented (c-face) sapphire substrate, which consists of an approximately 2-Etm-thick GaN template and a five-period layer consisting of a 4.9-nm-thick In0.18Ga0.82N well layer and a GaN barrier layer.The surface morphology of the MQW structures is observed by an atomic force microscope(AFM), which indicates the presence of islands of several tens of nanometers in height on the surface.The high resolution x-ray diffraction(XRD)θ/2θ scan is carried out on the symmetric(0002) of the InGaN/GaN MQW structures.At least four order satellite peaks presented in the XRD spectrum indicate that the thickness and alloy compositions of the individual quantum wells are repeatable throughout the active region.Besides the 364 nm GaN band edge emission, two main emissions of blue and amber light from these MQWs are found, which possibly originate from the carrier recombinations in the InGaN/GaN QWs and InGaN quasi-quantum dots embedded in the QWs.

  13. Photocurrent response of B12As2 crystals to blue light, and its temperature- dependent electrical characterizations

    Directory of Open Access Journals (Sweden)

    R. Gul

    2016-02-01

    Full Text Available With the global shortage of 3He gas, researchers worldwide are looking for alternative materials for detecting neutrons. Among the candidate materials, semiconductors are attractive because of their light weight and ease in handling. Currently, we are looking into the suitability of boron arsenide (B12As2 for this specific application. As the first step in evaluating the material qualitatively, the photo-response of B12As2 bulk crystals to light with different wavelengths was examined. The crystals showed photocurrent response to a band of 407- and 470- nm blue light. The maximum measured photoresponsivity and the photocurrent density at 0.7 V for 470 nm blue light at room temperature were 0.25 A ⋅ W−1 and 2.47 mA ⋅ cm−2, respectively. In addition to photo current measurements, the electrical properties as a function of temperature (range: 50-320 K were measured. Reliable data were obtained for the low-temperature I-V characteristics, the temperature dependence of dark current and its density, and the resistivity variations with temperature in B12As2 bulk crystals. The experiments showed an exponential dependence on temperature for the dark current, current density, and resistivity; these three electrical parameters, respectively, had a variation of a few nA to μA, 1-100 μA ⋅ cm−2 and 7.6x105-7.7x103 Ω ⋅ cm, for temperature increasing from 50 K to 320 K. The results from this study reported the first photoresponse and demonstrated that B12As2 is a potential candidate for thermal-neutron detectors.

  14. Photocurrent response of B12As2 crystals to blue light, and its temperature- dependent electrical characterizations

    International Nuclear Information System (INIS)

    With the global shortage of 3He gas, researchers worldwide are looking for alternative materials for detecting neutrons. Among the candidate materials, semiconductors are attractive because of their light weight and ease in handling. Currently, we are looking into the suitability of boron arsenide (B12As2) for this specific application. As the first step in evaluating the material qualitatively, the photo-response of B12As2 bulk crystals to light with different wavelengths was examined. The crystals showed photocurrent response to a band of 407- and 470- nm blue light. The maximum measured photoresponsivity and the photocurrent density at 0.7 V for 470 nm blue light at room temperature were 0.25 A ⋅ W−1 and 2.47 mA ⋅ cm−2, respectively. In addition to photo current measurements, the electrical properties as a function of temperature (range: 50-320 K) were measured. Reliable data were obtained for the low-temperature I-V characteristics, the temperature dependence of dark current and its density, and the resistivity variations with temperature in B12As2 bulk crystals. The experiments showed an exponential dependence on temperature for the dark current, current density, and resistivity; these three electrical parameters, respectively, had a variation of a few nA to μA, 1-100 μA ⋅ cm−2 and 7.6x105-7.7x103 Ω ⋅ cm, for temperature increasing from 50 K to 320 K. The results from this study reported the first photoresponse and demonstrated that B12As2 is a potential candidate for thermal-neutron detectors

  15. Topical and Intradermal Efficacy of Photodynamic Therapy with Methylene Blue and Light-Emitting Diode in the Treatment of Cutaneous Leishmaniasis Caused by Leishmania braziliensis

    OpenAIRE

    Sbeghen, Mônica Raquel; Voltarelli, Evandra Maria; Campois, Tácito Graminha; Kimura, Elza; Aristides, Sandra Mara Alessi; Hernandes, Luzmarina; Caetano, Wilker; Hioka, Noboru; Lonardoni, Maria Valdrinez Campana; Silveira, Thaís Gomes Verzignassi

    2015-01-01

    Introduction: The topical and intradermal photodynamic therapy (PDT) effect of methylene blue (MB) using light-emitting diode (LED) as light source (MB/LED-PDT) in the treatment of lesions of American cutaneous leishmaniasis (ACL) caused by Leishmania braziliensis in hamsters were investigated.

  16. The acclimation of Phaeodactylum tricornutum to blue and red light does not influence the photosynthetic light reaction but strongly disturbs the carbon allocation pattern.

    Directory of Open Access Journals (Sweden)

    Anne Jungandreas

    Full Text Available Diatoms are major contributors to the aquatic primary productivity and show an efficient acclimation ability to changing light intensities. Here, we investigated the acclimation of Phaeodactylum tricornutum to different light quality with respect to growth rate, photosynthesis rate, macromolecular composition and the metabolic profile by shifting the light quality from red light (RL to blue light (BL and vice versa. Our results show that cultures pre-acclimated to BL and RL exhibited similar growth performance, photosynthesis rates and metabolite profiles. However, light shift experiments revealed rapid and severe changes in the metabolite profile within 15 min as the initial reaction of light acclimation. Thus, during the shift from RL to BL, increased concentrations of amino acids and TCA cycle intermediates were observed whereas during the BL to RL shift the levels of amino acids were decreased and intermediates of glycolysis accumulated. Accordingly, on the time scale of hours the RL to BL shift led to a redirection of carbon into the synthesis of proteins, whereas during the BL to RL shift an accumulation of carbohydrates occurred. Thus, a vast metabolic reorganization of the cells was observed as the initial reaction to changes in light quality. The results are discussed with respect to a putative direct regulation of cellular enzymes by light quality and by transcriptional regulation. Interestingly, the short-term changes in the metabolome were accompanied by changes in the degree of reduction of the plastoquinone pool. Surprisingly, the RL to BL shift led to a severe inhibition of growth within the first 48 h which was not observed during the BL to RL shift. Furthermore, during the phase of growth arrest the photosynthetic performance did not change. We propose arguments that the growth arrest could have been caused by the reorganization of intracellular carbon partitioning.

  17. The Acclimation of Phaeodactylum tricornutum to Blue and Red Light Does Not Influence the Photosynthetic Light Reaction but Strongly Disturbs the Carbon Allocation Pattern

    Science.gov (United States)

    Jungandreas, Anne; Schellenberger Costa, Benjamin; Jakob, Torsten; von Bergen, Martin; Baumann, Sven; Wilhelm, Christian

    2014-01-01

    Diatoms are major contributors to the aquatic primary productivity and show an efficient acclimation ability to changing light intensities. Here, we investigated the acclimation of Phaeodactylum tricornutum to different light quality with respect to growth rate, photosynthesis rate, macromolecular composition and the metabolic profile by shifting the light quality from red light (RL) to blue light (BL) and vice versa. Our results show that cultures pre-acclimated to BL and RL exhibited similar growth performance, photosynthesis rates and metabolite profiles. However, light shift experiments revealed rapid and severe changes in the metabolite profile within 15 min as the initial reaction of light acclimation. Thus, during the shift from RL to BL, increased concentrations of amino acids and TCA cycle intermediates were observed whereas during the BL to RL shift the levels of amino acids were decreased and intermediates of glycolysis accumulated. Accordingly, on the time scale of hours the RL to BL shift led to a redirection of carbon into the synthesis of proteins, whereas during the BL to RL shift an accumulation of carbohydrates occurred. Thus, a vast metabolic reorganization of the cells was observed as the initial reaction to changes in light quality. The results are discussed with respect to a putative direct regulation of cellular enzymes by light quality and by transcriptional regulation. Interestingly, the short-term changes in the metabolome were accompanied by changes in the degree of reduction of the plastoquinone pool. Surprisingly, the RL to BL shift led to a severe inhibition of growth within the first 48 h which was not observed during the BL to RL shift. Furthermore, during the phase of growth arrest the photosynthetic performance did not change. We propose arguments that the growth arrest could have been caused by the reorganization of intracellular carbon partitioning. PMID:25111046

  18. Postpartum Blues

    Medline Plus

    Full Text Available ... baby blues). What are the baby blues? The word "blues" is not really correct since women with ... baby blues). What are the baby blues? The word "blues" is not really correct since women with ...

  19. Bright light exposure reduces TH-positive dopamine neurons: implications of light pollution in Parkinson's disease epidemiology

    OpenAIRE

    Romeo, Stefania; Viaggi, Cristina; Di Camillo, Daniela; Willis, Allison W.; Lozzi, Luca; Rocchi, Cristina; Capannolo, Marta; Aloisi, Gabriella; Vaglini, Francesca; Maccarone, Rita; Caleo, Matteo; Missale, Cristina; Racette, Brad A.; Corsini, Giovanni U.; Maggio, Roberto

    2013-01-01

    This study explores the effect of continuous exposure to bright light on neuromelanin formation and dopamine neuron survival in the substantia nigra. Twenty-one days after birth, Sprague–Dawley albino rats were divided into groups and raised under different conditions of light exposure. At the end of the irradiation period, rats were sacrificed and assayed for neuromelanin formation and number of tyrosine hydroxylase (TH)-positive neurons in the substantia nigra. The rats exposed to bright li...

  20. Determination of eye safety filter protection factors associated with retinal thermal hazard and blue light photochemical hazard for intense pulsed light sources

    International Nuclear Information System (INIS)

    An assessment is provided of protection factors afforded for retinal thermal hazard and blue light photochemical hazard for a range of filters used with intense pulsed light sources (IPLs). A characteristic IPL spectrum based on black body radiation at 5000 K with a low cut filter at 515 nm was identified as suitable for such estimations. Specific filters assessed included types with idealized transmission properties and also a range of types whose transmission characteristics were measured by means of a Bentham DMc150 spectroradiometer. Predicted behaviour based on these spectra is outlined which describes both the effectiveness of protection and the level of luminous transmittance afforded. The analysis showed it was possible to describe a figure of merit for a particular filter material relating the degree of protection provided and corresponding value of luminous transmittance. This consideration is important for providing users of IPL equipment with safety eyewear with adequate level of visual transmittance. (note)

  1. Bright light exposure reduces TH-positive dopamine neurons: implications of light pollution in Parkinson's disease epidemiology

    Science.gov (United States)

    Romeo, Stefania; Viaggi, Cristina; Di Camillo, Daniela; Willis, Allison W.; Lozzi, Luca; Rocchi, Cristina; Capannolo, Marta; Aloisi, Gabriella; Vaglini, Francesca; Maccarone, Rita; Caleo, Matteo; Missale, Cristina; Racette, Brad A.; Corsini, Giovanni U.; Maggio, Roberto

    2013-01-01

    This study explores the effect of continuous exposure to bright light on neuromelanin formation and dopamine neuron survival in the substantia nigra. Twenty-one days after birth, Sprague–Dawley albino rats were divided into groups and raised under different conditions of light exposure. At the end of the irradiation period, rats were sacrificed and assayed for neuromelanin formation and number of tyrosine hydroxylase (TH)-positive neurons in the substantia nigra. The rats exposed to bright light for 20 days or 90 days showed a relatively greater number of neuromelanin-positive neurons. Surprisingly, TH-positive neurons decreased progressively in the substantia nigra reaching a significant 29% reduction after 90 days of continuous bright light exposure. This decrease was paralleled by a diminution of dopamine and its metabolite in the striatum. Remarkably, in preliminary analysis that accounted for population density, the age and race adjusted Parkinson's disease prevalence significantly correlated with average satellite-observed sky light pollution. PMID:23462874

  2. Sleep-Wake Actigraphy and Light Exposure During Spaceflight-Long

    Science.gov (United States)

    Czeisler, Charles A.; Barger, Laura K.; Wright, Kenneth P., Jr.; Ronda, Joseph

    2009-01-01

    Sleep-Wake Actigraphy and Light Exposure During Spaceflight-Long (Sleep-Long) will examine the effects of spaceflight and ambient light exposure on the sleep-wake cycles of the crew members during long-duration stays on the space station.

  3. Blue electroluminescent materials based on 2,7-distyrylfluorene for organic light-emitting diodes

    International Nuclear Information System (INIS)

    A series of blue fluorescent 9,9-diethyl-2,7-distyryl-9H-fluorene derivatives with various capping moieties such as diphenylamino; diphenylphosphino; triphenylsilyl; phenoxy; phenylmercapto; phenylselenoxy; and triphenymethyl groups were synthesized using the Honor-Emmons reaction. The highest occupied molecular orbital-lowest unoccupied molecular orbital energy levels were characterized with a photoelectron spectrometer and rationalized with quantum mechanical density functional theory calculations. The electroluminescent properties were explored through the fabrication of multilayer devices with a structure of Indium-tin-oxide/N,N'-diphenyl-N,N'-(1-napthyl)-(1,1'-phenyl)-4,4'-diamine/ 2-methyl-9,10-di(2-naphthyl)anthracene:blue dopants (5-15 wt.%)/4,7-diphenyl-1,10-phenanthroline/lithium quinolate/Al. All devices, except that using NPh2, exhibited a Commission Internationale de I'Eclairage (CIE) y value less than 0.19. The best luminous efficiency of 3.87 cd/A and external quantum efficiency of 2.65% at 20 mA/cm2 were obtained in a device comprising the 4-phenylsulfanyl capped 9,9-diethyl-2,7-distyrylfluorene derivative with CIE coordinates (0.16, 0.18).

  4. Visible-light-driven photodegradation of sulfamethoxazole and methylene blue by Cu2O/rGO photocatalysts.

    Science.gov (United States)

    Liu, Shou-Heng; Wei, Yu-Shao; Lu, Jun-Sheng

    2016-07-01

    The cuprous oxide-reduced graphene oxide (Cu2O/rGO-x) composites were prepared via a simple wet-chemical method by using CuSO4·5H2O and graphene oxide as precursors and ascorbic acid as a reducing agent, respectively. These Cu2O/rGO-x were employed as photocatalysts for degrading emerging contaminants and organic dye pollutants (i.e., sulfamethoxazole (SMX) and methylene blue (MB)) under visible light. A variety of different spectroscopic and analytical techniques, such as X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy, Raman scattering spectroscopy and UV-Visible spectroscopy were used to characterize the physical properties of photocatalysts. In the photodegrading experiments, it can be found that the Cu2O/rGO-80 photocatalyst has the superior visible-light response of ca. 50% removal efficiency of SMX within 120 min and 100% removal efficiency of MB within 40 min. These observations may be attributed the well-dispersed and visible-light-responsive Cu2O nanoparticles are supported on the surface of rGO sheets that can enhance absorption of visible light during photocatalysis. PMID:27043377

  5. The Blues of David Lynch

    OpenAIRE

    Roche, David

    2009-01-01

    This article is an attempt to elaborate a typology of the color blue in the color films of David Lynch up to and including Mulholland Drive (2001). The color blue is considered alternately as light, matter or verbal language. The author studies the use, function, value and meaning of blue lighting, divided into static and flashing light, and of the blue objects in Blue Velvet (1986) and Mulholland Drive. The author shows how Lynch appropriates connotations Western culture, under the influence...

  6. Comparison of milk oxidation by exposure to LED and fluorescent light.

    Science.gov (United States)

    Brothersen, C; McMahon, D J; Legako, J; Martini, S

    2016-04-01

    Light-induced oxidation of milk has been well studied. Exposure of milk to UV light facilitates the oxidation of fats to aldehydes, and the degradation of sulfur-containing amino acids, both of which contribute to off-flavors. In addition, vitamin A and riboflavin are easily degraded by UV light. These reactions occur rapidly and are exacerbated by bright fluorescent lights in retail dairy cases. The invention of white light-emitting diodes (LED) may provide a solution to this oxidation problem. In this study, fresh milk containing 1% fat and fortified with vitamin A and riboflavin was exposed to LED at 4,000 lx, or fluorescent light at 2,200 lx for 24 h. Milk samples exposed to LED or fluorescent light, as well as milk protected from light, were analyzed by a consumer acceptance panel, and a trained flavor panel. In addition, vitamin A, riboflavin, and the production of volatile compounds were quantified. Exposure to light resulted in a reduction of cooked/sweet, milkfat, and sweet flavors and increased the intensity of butterscotch, cardboard, and astringency. In general, exposure to fluorescent light resulted in greater changes in the milk than exposure to LED even though the LED was at higher intensity. Consumers were able detect off-flavors in milk exposed to fluorescent light after 12 h and LED after 24 h of exposure. The riboflavin and vitamin A content was reduced by exposure to fluorescent light, whereas there was no significant reduction caused by LED compared with the non-light-exposed control. Production of hexanal, heptanal, 2-heptanal, octanal, 2-octanal nonanal, dimethyl sulfide, and caproic acid vinyl ester from the light-induced degradation of fats was significantly higher with fluorescent than LED. Production of these compounds was significantly higher with both light treatments than in the control milk. This study indicates that LED is less destructive to milk than fluorescent light. PMID:26874418

  7. An in vitro cell irradiation protocol for testing photopharmaceuticals and the effect of blue, green, and red light on human cancer cell lines.

    Science.gov (United States)

    Hopkins, S L; Siewert, B; Askes, S H C; Veldhuizen, P; Zwier, R; Heger, Michal; Bonnet, Sylvestre

    2016-05-11

    Traditionally, ultraviolet light (100-400 nm) is considered an exogenous carcinogen while visible light (400-780 nm) is deemed harmless. In this work, a LED irradiation system for in vitro photocytotoxicity testing is described. The LED irradiation system was developed for testing photopharmaceutical drugs, but was used here to determine the basal level response of human cancer cell lines to visible light of different wavelengths, without any photo(chemo)therapeutic. The effects of blue (455 nm, 10.5 mW cm(-2)), green (520 nm, 20.9 mW cm(-2)), and red light (630 nm, 34.4 mW cm(-2)) irradiation was measured for A375 (human malignant melanoma), A431 (human epidermoid carcinoma), A549 (human lung carcinoma), MCF7 (human mammary gland adenocarcinoma), MDA-MB-231 (human mammary gland adenocarcinoma), and U-87 MG (human glioblastoma-grade IV) cell lines. In response to a blue light dose of 19 J cm(-2), three cell lines exhibited a minimal (20%, MDA-MB-231) to moderate (30%, A549 and 60%, A375) reduction in cell viability, compared to dark controls. The other cell lines were not affected. Effective blue light doses that produce a therapeutic response in 50% of the cell population (ED50) compared to dark conditions were found to be 10.9 and 30.5 J cm(-2) for A375 and A549 cells, respectively. No adverse effects were observed in any of the six cell lines irradiated with a 19 J cm(-2) dose of 520 nm (green) or 630 nm (red) light. The results demonstrate that blue light irradiation can have an effect on the viability of certain human cancer cell types and controls should be used in photopharmaceutical testing, which uses high-energy (blue or violet) visible light activation. PMID:27098927

  8. Hybrid white organic light-emitting devices based on phosphorescent iridium–benzotriazole orange–red and fluorescent blue emitters

    International Nuclear Information System (INIS)

    We demonstrate that high color purity or efficiency hybrid white organic light-emitting devices (OLEDs) can be generated by integrating a phosphorescent orange–red emitter, bis[4-(2H-benzotriazol-2-yl)-N,N-diphenyl-aniline-N1,C3] iridium acetylacetonate, Ir(TBT)2(acac) with fluorescent blue emitters in two different emissive layers. The device based on deep blue fluorescent material diphenyl-[4-(2-[1,1′;4′,1″]terphenyl-4-yl-vinyl)-phenyl]-amine BpSAB and Ir(TBT)2(acac) shows pure white color with the Commission Internationale de L'Eclairage (CIE) coordinates of (0.33,0.30). When using sky-blue fluorescent dopant N,N′-(4,4′-(1E,1′E)-2,2′-(1,4-phenylene)bis(ethene-2,1-diyl) bis(4,1-phenylene))bis(2-ethyl-6-methyl-N-phenylaniline) (BUBD-1) and orange–red phosphor with a color-tuning phosphorescent material fac-tris(2-phenylpyridine) iridium (Ir(ppy)3 ), it exhibits peak luminance yield and power efficiency of 17.4 cd/A and 10.7 lm/W, respectively with yellow-white color and CIE color rendering index (CRI) value of 73. - Highlights: ► An iridium-based orange–red phosphor Ir(TBT)2(acac) was applied in hybrid white OLEDs. ► Duel- and tri-emitter WOLEDs were achieved with either high color purity or efficiency performance. ► Peak luminance yield of tri-emitter WOLEDs was 17.4 cd/A with yellow-white color and color rendering index (CRI) value of 73.

  9. Hybrid white organic light-emitting devices based on phosphorescent iridium-benzotriazole orange-red and fluorescent blue emitters

    Energy Technology Data Exchange (ETDEWEB)

    Xia, Zhen-Yuan, E-mail: xiazhenyuan@hotmail.com [Key Laboratory for Advanced Materials and Institute of Fine Chemicals, East China University of Science and Technology, Shanghai 200237 (China); Su, Jian-Hua [Key Laboratory for Advanced Materials and Institute of Fine Chemicals, East China University of Science and Technology, Shanghai 200237 (China); Chang, Chi-Sheng; Chen, Chin H. [Display Institute, Microelectronics and Information Systems Research Center, National Chiao Tung University, Hsinchu, Taiwan 300 (China)

    2013-03-15

    We demonstrate that high color purity or efficiency hybrid white organic light-emitting devices (OLEDs) can be generated by integrating a phosphorescent orange-red emitter, bis[4-(2H-benzotriazol-2-yl)-N,N-diphenyl-aniline-N{sup 1},C{sup 3}] iridium acetylacetonate, Ir(TBT){sub 2}(acac) with fluorescent blue emitters in two different emissive layers. The device based on deep blue fluorescent material diphenyl-[4-(2-[1,1 Prime ;4 Prime ,1 Double-Prime ]terphenyl-4-yl-vinyl)-phenyl]-amine BpSAB and Ir(TBT){sub 2}(acac) shows pure white color with the Commission Internationale de L'Eclairage (CIE) coordinates of (0.33,0.30). When using sky-blue fluorescent dopant N,N Prime -(4,4 Prime -(1E,1 Prime E)-2,2 Prime -(1,4-phenylene)bis(ethene-2,1-diyl) bis(4,1-phenylene))bis(2-ethyl-6-methyl-N-phenylaniline) (BUBD-1) and orange-red phosphor with a color-tuning phosphorescent material fac-tris(2-phenylpyridine) iridium (Ir(ppy){sub 3} ), it exhibits peak luminance yield and power efficiency of 17.4 cd/A and 10.7 lm/W, respectively with yellow-white color and CIE color rendering index (CRI) value of 73. - Highlights: Black-Right-Pointing-Pointer An iridium-based orange-red phosphor Ir(TBT){sub 2}(acac) was applied in hybrid white OLEDs. Black-Right-Pointing-Pointer Duel- and tri-emitter WOLEDs were achieved with either high color purity or efficiency performance. Black-Right-Pointing-Pointer Peak luminance yield of tri-emitter WOLEDs was 17.4 cd/A with yellow-white color and color rendering index (CRI) value of 73.

  10. Blue light absorption enhancement based on vertically channelling modes in nano-holes arrays

    CERN Document Server

    Gomard, Guillaume; Callard, Ségolène; Meng, Xianqin; Artinyan, Rémy; Deschamps, Thierry; Cabarrocas, Pere Roca I; Drouard, Emmanuel; Seassal, Christian

    2014-01-01

    We investigate the specific optical regime occurring at short wavelengths, in the high absorption regime, in silicon thin-films patterned by periodically arranged nano-holes. Near-field scanning optical microscopy indicates that the incoming light is coupled to vertically channelling modes. Optical modelling and simulations show that the light, travelling inside the low-index regions, is absorbed at the direct vicinity of the nano-holes sidewalls. This channelling regime should be taken into account for light management in optoelectronic devices.

  11. The blue-light receptor CmWC-1 mediates fruit body development and secondary metabolism in Cordyceps militaris.

    Science.gov (United States)

    Yang, Tao; Guo, Mingmin; Yang, Huaijun; Guo, Suping; Dong, Caihong

    2016-01-01

    Light is an essential factor for pigment formation and fruit body development in Cordyceps militaris, a well-known edible and medicinal fungus. Cmwc-1, a homolog of the blue-light receptor gene white collar-1 (wc-1) in Neurospora crassa, was cloned from the C. militaris genome in our previous study. Here, Cmwc-1 gene inactivation results in thicker aerial hyphae, disordered fruit body development, a significant reduction in conidial formation, and carotenoid and cordycepin production. These characteristics were restored when the ΔCmwc-1 strains were hybridized with wild-type strains of the opposite mating type. A genome-wide expression analysis revealed that there were 1042 light-responsive genes in the wild-type strain and only 458 in the ΔCmwc-1 strain. Among five putative photoreceptors identified, Vivid, cryptochrome-1, and cyclobutane pyrimidine dimer photolyase are strongly induced by light in a Cmwc-1-dependent manner, while phytochrome and cryptochrome-2 were not induced. The transcription factors involved in the fungal light reaction were mainly of the Zn2Cys6 type. CmWC-1 regulates adenylosuccinate synthase, an important enzyme for adenosine de novo synthesis, which could explain the reduction in cordycepin production. Some G protein-coupled receptors that control fungal fruit body formation and the sexual cycle were regulated by CmWC-1, and the cAMP pathway involved in light signal transduction in N. crassa was not critical for the photoreaction in the fungus here. A transcriptional analysis indicated that steroid biosynthesis was more active in the ΔCmwc-1 strain, suggesting that CmWC-1 might switch the vegetative growth state to primordia differentiation by suppressing the expression of related genes. PMID:26476643

  12. Photoelectrochemical degradation of Methylene Blue with β-PbO2 electrodes driven by visible light irradiation

    Institute of Scientific and Technical Information of China (English)

    Guoting Li; Ho Yin Yip; Kin Hang Wong; Chun Hu; Jiuhui Qu; Po Keung Wong

    2011-01-01

    β-PbO2 electrodes were prepared by electro-deposition and characterized by scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and linear sweep voltammetry. We confirmed pure β-PbO2 crystals were on the electrode and it had a high oxygen evolution potential. The photoactivity and photoelectrochemical (PEC) properties of the β-PbO2 electrode were investigated under visible light irradiation (λ > 420 nm) for the decolorization of Methylene Blue. Pseudo first-ordcr kinetics parameter (Kapp) for dye decolorization using the β-PbO2 electrode achieved 6.71×10-4 min-1 under visible light irradiation, which indicated its excellent visible light-induced photoactvity. The Kapp of the PEC process was as much as 1.41×10-3 min-1 and was 1.71 times that of visible light irradiation or electrolysis even in the presence of the β-PbO2 electrode. A significant synergetic effect was observed in the PEC system.We also employed TiO2 modified β-PbO2 electrodes in this test, which revealed that the TiO2 immobilized on the β-PbO2 electrode inhibited the visible light-induced PEC efficiency despite the amount of TiO2 used for electrode preparation. The β-PbO2 electrode was also superior to the dimensionally stable anode (Ti/Ru0.3Ti0.7O2) in visible light-induced photoactivity and PEC efficiency.

  13. Giantically blue-shifted visible light in femtosecond mid-IR filament in fluorides.

    Science.gov (United States)

    Dormidonov, A E; Kompanets, V O; Chekalin, S V; Kandidov, V P

    2015-11-01

    A giant blue shift (more than 3000 nm) of an isolated visible band of supercontinuum was discovered and studied in the single filament regime of Mid-IR femtosecond laser pulse at powers slightly exceeding critical power for self-focusing in fluorides. At the pulse central wavelength increasing from 3000 nm to 3800 nm the spectral maximum of the visible band is shifted from 570 nm and 520 nm up to 400 nm and 330 nm for BaF(2) and CaF(2), respectively, its spectral width (FWHM) being reduced from 50 - 70 nm to 14 nm. It is shown that the formation of this narrow visible wing is a result of the interference of the supercontinuum components in the anomalous group velocity dispersion regime. PMID:26561190

  14. Tuning Ag29 nanocluster light emission from red to blue with one and two-photon excitation.

    Science.gov (United States)

    Russier-Antoine, Isabelle; Bertorelle, Franck; Hamouda, Ramzi; Rayane, Driss; Dugourd, Philippe; Sanader, Željka; Bonačić-Koutecký, Vlasta; Brevet, Pierre-François; Antoine, Rodolphe

    2016-02-01

    We demonstrate that the tuning of the light emission from red to blue in dihydrolipoic acid (DHLA) capped Ag29 nanoclusters can be trigged with one and two photon excitations. The cluster stoichiometry was determined with mass spectrometry and found to be Ag29(DHLA)12. In a detailed optical investigation, we show that these silver nanoclusters exhibit a strong red photoluminescence visible to the naked eye and characterized by a quantum yield of nearly ∼2% upon one-photon excitation. In the nonlinear optical (NLO) study of the properties of the clusters, the two-photon excited fluorescence spectra were recorded and their first hyperpolarizability obtained. The two-photon absorption cross-section at ∼800 nm for Ag29(DHLA)12 is higher than 10(4) GM and the hyperpolarizability is 106 × 10(-30) esu at the same excitation wavelength. The two-photon excited fluorescence spectrum appears strongly blue-shifted as compared to the one-photon excited spectrum, displaying a broad band between 400 and 700 nm. The density functional theory (DFT) provides insight into the structural and electronic properties of Ag29(DHLA)12 as well as into interplay between metallic subunit or core and ligands which is responsible for unique optical properties. PMID:26765164

  15. Characteristics of doped TiO2 photocatalysts for the degradation of methylene blue waste water under visible light

    International Nuclear Information System (INIS)

    Fe-doped, N-doped, (Fe,N)-codoped and undoped TiO2 were prepared by a hydrothermal treatment, followed by a calcination process, using TiOSO4, CO(NH2)2 and Fe(NO3)3 as raw materials. The samples were characterized by XRD, XPS, TEM, PL, FT-IR and UV-Vis diffuse reflectance spectra. Photocatalytic experiments were carried out by decomposition of methylene blue aqueous solution under visible light. It was found that as-prepared TiO2-based catalysts were single phasic anatase titania. Among these samples, the N-doped TiO2 exhibited the better photocatalytic activity. The relations of their photocatalytic activity, spectroscopy properties and band gap structures have been discussed while ab initio calculations of electron structure and density of state (DOS) were done by DFT quantum chemistry method.

  16. Photocatalytic degradation of methylene blue on magnetically separable MgFe2O4 under visible light irradiation

    KAUST Repository

    Shahid, Muhammad

    2013-05-01

    A magnetically separable single-phase MgFe2O4 photocatalyst with a spinel crystal structure was synthesized by using the solid-state reaction method. The formation of spinel structure is confirmed by X-ray diffraction and Fourier transform infrared spectroscopy. The magnetic measurements showed that the photocatalyst material can be separated from water when an external magnetic field is added and redispersed into water solution after the external magnetic field is eliminated. It is one of the promising photocatalysts for waste water treatment. The photocatalytic activity of MgFe2O4 was investigated by using the photo-decomposition of methylene blue dye under visible light. The photoelectrochemical property of the MgFe2O4 was studied by measuring their photocurrent-potential behavior in 1 M NaOH electrolyte under AM 1.5100 mW cm-2 illumination. © 2013 Elsevier B.V. All rights reserved.

  17. Synthesis and blue light-emitting properties of 4,4'-bis(diphenylamino)-quinque(p-phenyl)s

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    An excellent organic blue light-emitting diode based on 4,4'-bis(diphenylamino)-quinque(p-phenylene)s (OPP(5)-NPh) with a maximum luminance of up to 5000 cd/m2 and a luminanous efficiency of 1.3 cd/A was reported. This diode was made by using a wide band-gap hole-blocking layer, F-TBB instead of PBD in the OLED devices. We attribute the good performance to the one trade-off involved in the use of F-TBB to obtain higher luminance is the increased turn-on voltages and slightly decreased device efficiencies.(C) 2007 Zhong Hui Li. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved.

  18. Performance improvement of InGaN blue light-emitting diodes with several kinds of electron-blocking layers

    Institute of Scientific and Technical Information of China (English)

    Chen Jun; Fan Guang-Han; Zhang Yun-Yan; Pang Wei; Zheng Shu-Wen; Yao Guang-Rui

    2012-01-01

    The performance of lnGaN blue light-emitting diodes(LEDs)with different kinds of electron-blocking layers is investigated numerically.We compare the simulated emission spectra,electron and hole concentrations,euergy band diagrams,electrostatic fields,and internal quantum efficiencies of the LEDs.The LED using A1GaN with gradually increasing Al content from 0% to 20% as the electron-blocking layer(EBL)has a strong spectrum intensity,mitigates efficiency droop,and possesses higher output power compared with the LEDs with the other three types of EBLs.These advantages could be because of the lower electron leakage current and more effective hole injection.The optical performance of the specifically designed LED is also improved in the case of large injection current.

  19. Junction temperature, spectral shift, and efficiency in GaInN-based blue and green light emitting diodes

    International Nuclear Information System (INIS)

    The junction temperature of homoepitaxial green and blue GaInN/GaN quantum well light emitting diode (LED) dies is analyzed by micro-Raman, photoluminescence, cathodoluminescence mapping, and forward-voltage methods and compared to finite element simulations. Dies on GaN substrate and sapphire were analyzed under variable drive current up to 200 mA (246 A/cm2). At 100 mA, dies on bulk GaN remain as cool as 355 K (83 oC) while dies on sapphire heat up to 477 K (204 oC). The efficiency droop and spectral line shift in green LEDs with increasing current density can now be separated into electrical and thermal contributions.

  20. Structural Insights into the HWE Histidine Kinase Family: The Brucella Blue Light-Activated Histidine Kinase Domain.

    Science.gov (United States)

    Rinaldi, Jimena; Arrar, Mehrnoosh; Sycz, Gabriela; Cerutti, María Laura; Berguer, Paula M; Paris, Gastón; Estrín, Darío Ariel; Martí, Marcelo Adrián; Klinke, Sebastián; Goldbaum, Fernando Alberto

    2016-03-27

    In response to light, as part of a two-component system, the Brucella blue light-activated histidine kinase (LOV-HK) increases its autophosphorylation, modulating the virulence of this microorganism. The Brucella histidine kinase (HK) domain belongs to the HWE family, for which there is no structural information. The HWE family is exclusively present in proteobacteria and usually coupled to a wide diversity of light sensor domains. This work reports the crystal structure of the Brucella HK domain, which presents two different dimeric assemblies in the asymmetric unit: one similar to the already described canonical parallel homodimers (C) and the other, an antiparallel non-canonical (NC) dimer, each with distinct relative subdomain orientations and dimerization interfaces. Contrary to these crystallographic structures and unlike other HKs, in solution, the Brucella HK domain is monomeric and still active, showing an astonishing instability of the dimeric interface. Despite this instability, using cross-linking experiments, we show that the C dimer is the functionally relevant species. Mutational analysis demonstrates that the autophosphorylation activity occurs in cis. The different relative subdomain orientations observed for the NC and C states highlight the large conformational flexibility of the HK domain. Through the analysis of these alternative conformations by means of molecular dynamics simulations, we also propose a catalytic mechanism for Brucella LOV-HK. PMID:26851072

  1. Retinal vascular calibre and response to light exposure and serial imaging

    DEFF Research Database (Denmark)

    von Hanno, T.; Sjølie, Anne K.; Mathiesen, E. B.

    2014-01-01

    Purpose: To investigate whether retinal vessel calibre measurements on optical retinal photography are affected by light and dark exposure prior to photography and whether the vessel calibre changes during an imaging sequence of several images. Methods: Digital optical retinal photographs were...... obtained from 32 healthy adults in two separate image sequences of six images during 1 min; one sequence with 10 min of dark exposure and one with 10 min of light exposure prior to imaging. Retinal arteriolar and venular calibres were measured computer-assisted and summarized as central retinal artery and...... vein equivalents (CRAE and CRVE). Outcome measures were difference in calibres after prior light versus prior dark exposure and difference in calibre during each of the two imaging sequences. Results: CRVE was wider with prior light exposure (2.7%, p = 0.0001), comparing the first image in each image...

  2. Spectral optimization of the color temperature tunable white light-emitting diode (LED) cluster consisting of direct-emission blue and red LEDs and a diphosphor conversion LED.

    Science.gov (United States)

    Zhong, Ping; He, Guoxing; Zhang, Minhao

    2012-09-10

    The correlated color temperature (CCT) tunable white-light LED cluster, which consists of direct-emission blue and red LEDs as well as phosphor-conversion (PC) LEDs packaged by combining green and orange phosphors with a blue LED die, has been obtained by nonlinear program for maximizing luminous efficacy (LE) of radiation (LER) under conditions of both color rendering index (CRI) and special CRI of R9 for strong red above 90 at CCTs of 2700 K to 6500 K. The optimal peak wavelengths of blue LED, red LED, blue LED die, green and orange phosphors are 465 nm, 628 nm, 452 nm, 530 nm and 586 nm, respectively. The real CCT tunable PC/red/blue LED cluster with CRIs of 90~96, R9s of 90~96, CQSs of 89~94, LERs of 303~358 lm/W, and LEs of 105~119 lm/W has been realized at CCTs of 2722 K to 6464 K. The deviation of the peak wavelength should be less than ± 5 nm for blue LED die, ± 1 nm for red LED, and ± 2 nm for blue LED to achieve the PC/R/B LED cluster with high optical performance. PMID:23037535

  3. Spatially Resolved Cathodoluminescence in the Vicinity of Defects in the High-Efficiency InGaN/GaN Blue Light Emitting Diodes

    Directory of Open Access Journals (Sweden)

    Manh-Ha Doan

    2014-01-01

    Full Text Available In addition to the standard 447 nm blue emission from the InGaN/GaN multiple quantum wells, a high-energy shoulder is clearly observed in cathodoluminescence spectra of the high-efficiency InGaN/GaN blue light emitting diodes grown on sapphire substrates by metalorganic chemical vapor deposition. Monochromatic cathodoluminescence images of the samples measured at low temperature reveal a competition between the two emissions in the vicinity of the dislocations. The high-energy emission is dominant at the regions near the dislocation cores, while the blue emission is enhanced around the dislocation edges. The high-energy emission region is considered as a potential barrier that prevents the carriers for the blue emission from nonradiatively recombining at the dislocations.

  4. Analysis of circadian properties and healthy levels of blue light from smartphones at night

    Science.gov (United States)

    Oh, Ji Hye; Yoo, Heeyeon; Park, Hoo Keun; Do, Young Rag

    2015-06-01

    This study proposes representative figures of merit for circadian and vision performance for healthy and efficient use of smartphone displays. The recently developed figures of merit for circadian luminous efficacy of radiation (CER) and circadian illuminance (CIL) related to human health and circadian rhythm were measured to compare three kinds of commercial smartphone displays. The CIL values for social network service (SNS) messenger screens from all three displays were higher than 41.3 biolux (blx) in a dark room at night, and the highest CIL value reached 50.9 blx. These CIL values corresponded to melatonin suppression values (MSVs) of 7.3% and 11.4%, respectively. Moreover, smartphone use in a bright room at night had much higher CIL and MSV values (58.7 ~ 105.2 blx and 15.4 ~ 36.1%, respectively). This study also analyzed the nonvisual and visual optical properties of the three smartphone displays while varying the distance between the screen and eye and controlling the brightness setting. Finally, a method to possibly attenuate the unhealthy effects of smartphone displays was proposed and investigated by decreasing the emitting wavelength of blue LEDs in a smartphone LCD backlight and subsequently reducing the circadian effect of the display.

  5. The effect of heavy metal exposure on egg size, eggshell thickness and the number of spermatozoa in blue tit Parus caeruleus eggs

    International Nuclear Information System (INIS)

    In this study we compared the egg size, the eggshell thickness and the number of spermatozoa trapped on the perivitelline layer of the eggs in three blue tit (Parus caeruleus) populations across a heavy metal pollution gradient. No significant differences were observed in egg characteristics among study sites. Eggs from the two most polluted sites however, had significantly less spermatozoa on the perivitelline layer than eggs from the least polluted site. Our results suggest a significant effect of pollution on blue tit sperm concentrations in the infundibulum. Determining the number of spermatozoa on the egg membranes is relatively cheap and straightforward, which renders this technique a new and useful tool in biomonitoring. - Exposure to elevated levels of heavy metals had a negative effect on the number of spermatozoa in the eggs of free-living blue tits (Parus caeruleus)

  6. Prenatal radiation exposure. Conclusions in the light of radiology

    International Nuclear Information System (INIS)

    Within 6 years of the appearance of the guideline for action to be taken by doctors in the event of prenatal exposure to radiation, intended as a proposal for discussion, the following has turned out: in no case has termination of pregnancy become necessary following prenatal radiation exposure, prenatal radiation exposure was always low (about 20 mSv), there is no risk below respective threshold doses, teratogenesis is a non-stochastic process, which is why risk assessment was modified, the sensitivity of the human fetus to radiation is highest during the period of neuroblast development (9th to 16th week p.c.), and knowledge about an existing pregnancy can be taken for granted by that time, so radiation exposure is calculable and can be restricted to negligible quantities. (TRV)

  7. Dry etching characteristics of GaN for blue/green light-emitting diode fabrication

    International Nuclear Information System (INIS)

    The etch rates, surface morphology and sidewall profiles of features formed in GaN/InGaN/AlGaN multiple quantum well light-emitting diodes by Cl2-based dry etching are reported. The chlorine provides an enhancement in etch rate of over a factor of 40 relative to the physical etching provided by Ar and the etching is reactant-limited until chlorine gas flow rates of at least 50 standard cubic centimeters per minute. Mesa sidewall profile angle control is possible using a combination of Cl2/Ar plasma chemistry and SiO2 mask. N-face GaN is found to etch faster than Ga-face surfaces under the same conditions. Patterning of the sapphire substrate for improved light extraction is also possible using the same plasma chemistry

  8. Changes on degree of conversion of dual-cure luting light-cured with blue LED

    Science.gov (United States)

    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 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.

  9. Bilirubin isomer distribution in jaundiced neonates during phototherapy with LED light centered at 497 nm (turquoise) vs. 459 nm (blue)

    DEFF Research Database (Denmark)

    Ebbesen, Finn; Madsen, Poul H; Vandborg, Pernille K;

    2016-01-01

    of jaundiced neonates after 24 h of therapy with narrow-band (LED) light centered at 497 nm (turquoise) vs. 459 nm (blue), of essentially equal irradiance. MATERIALS: Eighty-three neonates (≥33 wk gestational age) with uncomplicated hyperbilirubinemia were included in the study. Forty neonates were...... difference was found between concentrations of E,Z-lumirubin. CONCLUSION: Therapy with LED light centered at 497 nm vs. 459 nm, applied with equal irradiance on the infants, resulted in a different distribution of bilirubin isomers in serum.Pediatric Research (2016); doi:10.1038/pr.2016.115.......BACKGROUND: Phototherapy using blue light is the treatment of choice worldwide for neonatal hyperbilirubinemia. However, treatment with turquoise light may be a desirable alternative. Therefore, the aim of this randomized, controlled study was to compare the bilirubin isomer distribution in serum...

  10. Enhanced visible-light-response photocatalytic degradation of methylene blue on Fe-loaded BiVO4 photocatalyst

    International Nuclear Information System (INIS)

    Highlights: • Fe-loaded BiVO4 particles were prepared by hydrothermal method. • Physicochemical properties played a significant role in photocatalytic process. • All Fe-loaded BiVO4 samples showed higher photocatalytic activity than pure BiVO4. • The Fe3+ ions may improve the separation of photogenerated electrons and holes. - Abstract: Pure BiVO4 and nominal 0.5–5.0 mol% Fe-loaded BiVO4 samples were synthesized by hydrothermal method. All samples were characterized in order to obtain the correlation between structure and photocatalytic properties by X-ray diffraction, Brunauer, Emmett and Teller, UV–vis diffuse reflectance spectrophotometry, photoluminescence spectroscopy, transmission electron microscopy, X-ray photoelectron spectroscopy and inductively coupled plasma-optical emission spectroscopy. The structure of all samples was single-phase monoclinic scheelite. The absorption spectrum of 5.0 mol% Fe-loaded BiVO4 shifted to the visible region, suggesting the potential application of this material as a superior visible-light driven photocatalyst in comparison with pure BiVO4. Photocatalytic activities of all photocatalyst samples were examined by studying the degradation of methylene blue under visible light irradiation. The results clearly showed that Fe-loaded BiVO4 sample exhibited remarkably higher activity than pure BiVO4

  11. Enhanced photocatalytic activity of CeO2 using β-cyclodextrin on visible light assisted decoloration of methylene blue.

    Science.gov (United States)

    Pitchaimuthu, Sakthivel; Velusamy, Ponnusamy

    2014-01-01

    An attempt has been made to enhance the photocatalytic activity of CeO(2) for visible light assisted decoloration of methylene blue (MB) dye in aqueous solutions by β-cyclodextrin (β-CD). The inclusion complexation patterns between host and guest (i.e., β-CD and MB) have been confirmed with UV-visible spectral data. The interaction between CeO(2) and β-CD has also been characterized by field emission scanning electron microscopy analysis. The photocatalytic activity of the catalyst under visible light was investigated by measuring the photodegradation of MB in aqueous solution. The effects of key operational parameters such as initial dye concentration, initial pH, CeO(2) concentration as well as illumination time on the decolorization extents were investigated. Among the processing parameters, the pH of the reaction solution played an important role in tuning the photocatalytic activity of CeO(2). The maximum photodecoloration rate was achieved at basic pH (pH 11). Under the optimum operational conditions, approximately 99.6% dye removal was achieved within 120 min. The observed results indicate that the decolorization of the MB followed a pseudo-first order kinetics. PMID:24434976

  12. Enhanced visible-light-response photocatalytic degradation of methylene blue on Fe-loaded BiVO{sub 4} photocatalyst

    Energy Technology Data Exchange (ETDEWEB)

    Chala, Sinaporn [Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Wetchakun, Khatcharin [Program of Physics, Faculty of Science, Ubon Ratchathani Rajabhat University, Ubon Ratchathani 34000 (Thailand); Phanichphant, Sukon [Materials Science Research Centre, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Inceesungvorn, Burapat [Department of Chemistry, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Wetchakun, Natda, E-mail: natda_we@yahoo.com [Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand)

    2014-06-01

    Highlights: • Fe-loaded BiVO{sub 4} particles were prepared by hydrothermal method. • Physicochemical properties played a significant role in photocatalytic process. • All Fe-loaded BiVO{sub 4} samples showed higher photocatalytic activity than pure BiVO{sub 4}. • The Fe{sup 3+} ions may improve the separation of photogenerated electrons and holes. - Abstract: Pure BiVO{sub 4} and nominal 0.5–5.0 mol% Fe-loaded BiVO{sub 4} samples were synthesized by hydrothermal method. All samples were characterized in order to obtain the correlation between structure and photocatalytic properties by X-ray diffraction, Brunauer, Emmett and Teller, UV–vis diffuse reflectance spectrophotometry, photoluminescence spectroscopy, transmission electron microscopy, X-ray photoelectron spectroscopy and inductively coupled plasma-optical emission spectroscopy. The structure of all samples was single-phase monoclinic scheelite. The absorption spectrum of 5.0 mol% Fe-loaded BiVO{sub 4} shifted to the visible region, suggesting the potential application of this material as a superior visible-light driven photocatalyst in comparison with pure BiVO{sub 4}. Photocatalytic activities of all photocatalyst samples were examined by studying the degradation of methylene blue under visible light irradiation. The results clearly showed that Fe-loaded BiVO{sub 4} sample exhibited remarkably higher activity than pure BiVO{sub 4}.

  13. Photocatalytic degradation of methylene blue on Fe3+-doped TiO2 nanoparticles under visible light irradiation

    Institute of Scientific and Technical Information of China (English)

    SU Bitao; WANG Ke; BAI Jie; MU Hongmei; TONG Yongchun; MIN Shixiong; SHE Shixiong; LEI Ziqiang

    2007-01-01

    Fe3+-doped TiO2 composite nanoparticles with different doping amounts were successfully synthesized using sol-gel method and characterized by X-ray diffraction (XRD),transmission electron microscopy (TEM) and ultraviolet-visible spectroscopy (UV-Vis) diffuse reflectance spectra (DRS). The photocatalytic degradation of methylene blue was used as a model reaction to evaluate the photocatalytic activity of Fe3+/TiO2 nanoparticles under visible light irradia-tion. The influence of doping amount of Fe3+ (ω: 0.00%-3.00%) on photocatalytic activities of TiO2 was investigated.Results show that the size of Fe3+/TiO2 particles decreases with the increase of the amount of Fe3+ and their absorptionspectra are broaden and absorption intensities are also increased. Doping Fe3+ can control the conversion of TiO2 from anatase to rutile. The doping amount of Fe3+ remarkably affects the activity of the catalyst, and the optimum efficiency occurs at about the doping amount of 0.3%. The appropriate doping of Fe3+ can markedly increase the catalytic activity of TiO2 under visible light irradiation.

  14. LED手电筒蓝光危害检测与分析%Test and Analysis on the Blue Light Hazard of LED Flashlights

    Institute of Scientific and Technical Information of China (English)

    胡苏军; 黄俊浩

    2015-01-01

    LED手电筒出射光束亮度大、色温高,蓝光发光成分位于400nm~500nm波段,蓝光辐射危害比较严重。依据国家标准GB/T 20145-2006,在0.2m和1.0m距离下,LED手电筒蓝光危害达到中度危险等级,如无防护措施可能对人眼造成严重伤害。分析发现,LED手电筒蓝光危害与手电筒的聚光性能、出射光束的亮度和色温密切相关。%The brightness and color temperature of LED flashlight beams are much higher, and the blue emission component located in the region of 400nm ~ 500nm, thus the blue light hazards of LED flashlights are more serious. According to the national standard, GB/T 20145-2006, the blue light hazards of LED flashlights can reach the moder-ate risk group under the distances of 0.2m and 1.0m; it may cause serious damage to human eyes without protective measures. Based on the analysis, we found out that the blue light hazard of LED flashlights is closely related to their light concentration properties, brightness and color temperature of beams.

  15. Research data supporting "Bright and efficient blue polymer light emitting diodes with reduced operating voltages processed entirely at low-temperature"

    OpenAIRE

    Hoye, R. L. Z.; Musselman, K.P.; Chua, M. R.; Sadhanala, A.; Raninga, R. D.; MacManus-Driscoll, J. L.; Friend, R. H.; Credgington, D.

    2015-01-01

    Raw data for all figures and ESI from manuscript "Bright and efficient blue polymer light emitting diodes with reduced operating voltages processed entirely at low-temperature" published in Journal of Materials Chemistry C (http://dx.doi.org/10.1039/C5TC01581B).

  16. The 7B-1 mutation in tomato (Solanum lycopersicum L.) confers a blue light-specific lower sensitivity to coronatine, a toxin produced by Pseudomonas syringae pv. tomato

    Czech Academy of Sciences Publication Activity Database

    Bergougnoux, V.; Hlaváčková, V.; Plotzová, R.; Novák, Ondřej; Fellner, Martin

    2009-01-01

    Roč. 60, č. 4 (2009), s. 1219-1230. ISSN 0022-0957 Institutional research plan: CEZ:AV0Z50380511 Keywords : Blue light-specific response * COI1 * coronatine Subject RIV: EF - Botanics Impact factor: 4.271, year: 2009

  17. Fluorescent blue lights, injecting drug use and related health risk in public conveniences: findings from a qualitative study of micro-injecting environments.

    Science.gov (United States)

    Parkin, Stephen; Coomber, Ross

    2010-07-01

    This paper presents findings relating to injecting drug users' experiences and opinions of public toilets illuminated with fluorescent blue lights and presents an empirical assessment of the intended deterrent effect of such installations. Data analysis identified that blue lights deterred less than half the sample interviewed. Furthermore over half (18/31) of the sample were prepared to inject in conditions specifically designed to deter injecting practice. Of these, 11 respondents were completely undeterred and 7 individuals were only partially deterred by blue light environments. These findings are discussed within the interpretative frameworks of Pierre Bourdieu's theory of habitus and symbolic violence. The authors conclude that fluorescent blue lights contribute towards the development of situated resistance by injecting drug users within a public injecting habitus; a resistance that produces and reproduces drug-related harm and is a behaviour that opposes the symbolic violence of harm reduction intervention. The paper concludes with suggestions for theory-driven practical intervention that may seek to disrupt the harmful elements of the public injecting habitus. PMID:20167527

  18. Episodic modulations in supernova radio light curves from luminous blue variable supernova progenitor models

    OpenAIRE

    Moriya, Takashi J.; Groh, Jose H.; Meynet, Georges

    2013-01-01

    Ideally, one would like to know which type of core-collapse SNe is produced by different progenitors and the channels of stellar evolution leading to these progenitors. These links have to be very well known to use the observed frequency of different types of SN events for probing the star formation rate and massive star evolution in different types of galaxies. We investigate the link between LBV as SN progenitors and the appearance of episodic radio light curve modulations of the SN event...

  19. Temperature-dependent efficiency droop of blue InGaN micro-light emitting diodes

    International Nuclear Information System (INIS)

    Temperature-dependent trends in radiative and Auger recombination coefficients have been determined at different injection carrier concentrations using InGaN micro-light emitting diodes 40 μm in diameter. The differential lifetime was obtained first from the measured modulation bandwidth and was then employed to calculate the carrier concentration in the quantum well active region. When the temperature increases, the carrier concentration increases, but both the radiative and Auger recombination coefficients decrease. In addition, the temperature dependence of radiative and Auger recombination coefficients is weaker at a higher injection carrier concentration, which is strongly related to phase space filling.

  20. Backswitch poling in lithium niobate for high-fidelity domain patterning and efficient blue light generation

    Science.gov (United States)

    Batchko, Robert G.; Shur, Vladimir Y.; Fejer, Martin M.; Byer, Robert L.

    1999-09-01

    In nonlinear optics applications employing quasiphase matching, short-pitch domain gratings are generally required for the efficient generation of visible and ultraviolet light. Here we introduce an improved electric-field poling technique, which incorporates spontaneous backswitching and leads to uniform short-pitch domain structures. The total volume of backswitched material, and hence the duty cycle of the backswitched domain grating, can be accurately controlled. First-order single-pass continuous-wave second harmonic generation of 60 mW at 460 nm is achieved at 6.1%/W efficiency in 0.5-mm-thick 4-μm-period backswitch-poled lithium niobate.

  1. Further investigations into pulsed optically stimulated luminescence from feldspars using blue and green light

    DEFF Research Database (Denmark)

    Ankjærgaard, Christina; Jain, Mayank; Kalchgruber, R.;

    2009-01-01

    -resolved optically stimulated luminescence (TR-OSL), and these signals can be mathematically described as a sum of 4 exponential components (a, b, c, d). The slowest component, d, increases with the duration of the light pulse as expected from the exponential model. The stimulation temperature dependence experiment...... suggests that the TR-OSL signal decay is governed by the recombination process and not by the excited state lifetime. Furthermore data from the TR-OSL signal dependence on stimulation time and preheat temperature suggest that the recombination process may not be a sum of exponentials, although the model...... cannot be rejected definitively....

  2. An Investigation of Color Memory as a Function of Hue, Saturation, Lightness and Observer Imagery Vividness for Blue, Green and Orange Test Hues

    OpenAIRE

    Laws, Eric L.

    2000-01-01

    Observer Imagery Vividness for Blue, Green and Orange Test Hues By Eric L. Laws Committee Chair: Dr. A. M. Prestrude Department of Psychology (Abstract) Fifty-two college-aged observers participated in an experiment assessing color memory via a PowerPoint '97 computer display program which varied one of the three dimensions of hue, saturation and lightness at a time. Consistent with previous research, errors were greater for the lightness conditions followed by saturation...

  3. Sonophotocatalytic degradation of trypan blue and vesuvine dyes in the presence of blue light active photocatalyst of Ag3PO4/Bi2S3-HKUST-1-MOF: Central composite optimization and synergistic effect study.

    Science.gov (United States)

    Mosleh, S; Rahimi, M R; Ghaedi, M; Dashtian, K

    2016-09-01

    An efficient simultaneous sonophotocatalytic degradation of trypan blue (TB) and vesuvine (VS) using Ag3PO4/Bi2S3-HKUST-1-MOF as a novel visible light active photocatalyst was carried out successfully in a continuous flow-loop reactor equipped to blue LED light. Ag3PO4/Bi2S3-HKUST-1-MOF with activation ability under blue light illumination was synthesized and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray (EDX), photoluminescence (PL) and diffuse reflectance spectra (DRS). The effect of operational parameters such as the initial TB and VS concentration (5-45mg/L), flow rate (30-110mL/min), irradiation and sonication time (10-30min), pH (3-11) and photocatalyst dosage (0.15-0.35g/L) has been investigated and optimized using central composite design (CCD) combined with desirability function (DF). Maximum sonophotodegradation percentage (98.44% and 99.36% for TB and VS, respectively) was found at optimum condition set as: 25mg/L of each dye, 70mL/min of solution flow rate, 25min of irradiation and sonication time, pH 6 and 0.25g/L of photocatalyst dosage. At optimum conditions, synergistic index value was obtained 2.53 that indicated the hybrid systems including ultrasound irradiation and photocatalysis have higher efficiency compared with sum of the individual processes. PMID:27150785

  4. Visible-light-induced blue MoO{sub 3}–C{sub 3}N{sub 4} composite with enhanced photocatalytic activity

    Energy Technology Data Exchange (ETDEWEB)

    Li, Yeping, E-mail: ypli@ujs.edu.cn [School of Pharmacy, Jiangsu University, Zhenjiang 212013 (China); Huang, Liying [School of Chemistry and Chemical Engineering, Jiangsu University, Zhenjiang 212013 (China); Xu, Jingbo [School of Pharmacy, Jiangsu University, Zhenjiang 212013 (China); Xu, Hui [Institute for Energy Research, Jiangsu University, Zhenjiang 212013 (China); Xu, Yuanguo; Xia, Jixiang [School of Chemistry and Chemical Engineering, Jiangsu University, Zhenjiang 212013 (China); Li, Huaming, E-mail: lihm@ujs.edu.cn [Institute for Energy Research, Jiangsu University, Zhenjiang 212013 (China)

    2015-10-15

    Highlights: • Novel MoO{sub 3}–C{sub 3}N{sub 4} composite was prepared by a mixing-calcination method. • The MoO{sub 3}–C{sub 3}N{sub 4} composite shows remarkably enhanced absorption of visible light. • The MoO{sub 3}–C{sub 3}N{sub 4} composite shows superior visible-light photocatalytic activity. - Abstract: Composite photocatalyst of blue MoO{sub 3}/g-C{sub 3}N{sub 4} (denoted as MoO{sub 3}–C{sub 3}N{sub 4}) was prepared by a simple mixing-calcination method. The obtained MoO{sub 3}–C{sub 3}N{sub 4} composite contains a low amount of molybdenum blue and shows remarkably enhanced absorption of visible light and high efficiency for the degradation of methylene blue dye (MB) under visible light. The enhancement of visible light photocatalytic activity in MoO{sub 3}–C{sub 3}N{sub 4} is attributed to the synergetic effect: (i) the strong and wide absorption of visible light, (ii) the high separation and easy transfer of photogenerated electron–hole pairs at the heterojunction interfaces derived from the match of band position between the g-C{sub 3}N{sub 4} and MoO{sub 3}.

  5. Blue light alters miR167 expression and microRNA-targeted auxin response factor genes in Arabidopsis thaliana plants.

    Science.gov (United States)

    Pashkovskiy, Pavel P; Kartashov, Alexander V; Zlobin, Ilya E; Pogosyan, Sergei I; Kuznetsov, Vladimir V

    2016-07-01

    The effect of blue LED (450 nm) on the photomorphogenesis of Arabidopsis thaliana Col-0 plants and the transcript levels of several genes, including miRNAs, photoreceptors and auxin response factors (ARF) was investigated. It was observed that blue light accelerated the generative development, reduced the rosette leaf number, significantly reduced the leaf area, dry biomass and led to the disruption of conductive tissue formation. The blue LED differentially influenced the transcript levels of several phytochromes (PHY a, b, c, d, and e), cryptochromes (CRY 1 and 2) and phototropins (PHOT 1 and 2). At the same time, the blue LED significantly increased miR167 expression compared to a fluorescent lamp or white LEDs. This increase likely resulted in the enhanced transcription of the auxin response factor genes ARF4 and ARF8, which are regulated by this miRNA. These findings support the hypothesis that the effects of blue light on A. thaliana are mediated by auxin signalling pathway involving miRNA-dependent regulation of ARF gene expression. PMID:27031426

  6. Quasi-homoepitaxial GaN-based blue light emitting diode on thick GaN template

    International Nuclear Information System (INIS)

    The high power GaN-based blue light emitting diode (LED) on an 80-μm-thick GaN template is proposed and even realized by several technical methods like metal organic chemical vapor deposition (MOCVD), hydride vapor-phase epitaxial (HVPE), and laser lift-off (LLO). Its advantages are demonstrated from material quality and chip processing. It is investigated by high resolution X-ray diffraction (XRD), high resolution transmission electron microscope (HRTEM), Rutherford back-scattering (RBS), photoluminescence, current-voltage and light output-current measurements. The width of (0002) reflection in XRD rocking curve, which reaches 173″ for the thick GaN template LED, is less than that for the conventional one, which reaches 258″. The HRTEM images show that the multiple quantum wells (MQWs) in 80-μm-thick GaN template LED have a generally higher crystal quality. The light output at 350 mA from the thick GaN template LED is doubled compared to traditional LEDs and the forward bias is also substantially reduced. The high performance of 80-μm-thick GaN template LED depends on the high crystal quality. However, although the intensity of MQWs emission in PL spectra is doubled, both the wavelength and the width of the emission from thick GaN template LED are increased. This is due to the strain relaxation on the surface of 80-μm-thick GaN template, which changes the strain in InGaN QWs and leads to InGaN phase separation. (condensed matter: structural, mechanical, and thermal properties)

  7. Lethal effect of blue light-activated hydrogen peroxide, curcumin and erythrosine as potential oral photosensitizers on the viability of Porphyromonas gingivalis and Fusobacterium nucleatum

    Science.gov (United States)

    Habiboallh, Ghanbari; Mahbobeh, Naderi Nasab; Mina, Zareian Jahromi; Majid, Zakeri; Nooshin, Arjmand

    2015-01-01

    Objectives: Recently, photodynamic therapy (PDT) has been introduced as a new modality in oral bacterial decontamination. Current research aims to evaluate the effect of photodynamic killing of visible blue light in the presence of hydrogen peroxide, curcumin and erythrosine as potential oral photosensitizers on Porphyromonas gingivalis associated with periodontal bone loss and Fusobacterium nucleatum associated with soft tissue inflammation. Materials and methods: Standard suspension of P. gingivalis and F. nucleatum were exposed to Light Emitting Diode (LED) (440–480 nm) in combination with erythrosine (22 µm), curcumin (60 µM) and hydrogen peroxide (0.3 mM) for 5 min. Bacterial samples from each treatment groups (radiation-only group, photosensitizer-only group and blue light-activated photosensitizer group) were subcultured onto the surface of agar plates. Survival of these bacteria was determined by counting the number of colony forming units (CFU) after incubation. Results: Results for antibacterial assays on P. gingivalis confirmed that curcumin, Hydrogen peroxide and erythrosine alone exerted a moderate bactericidal effect which enhanced noticeably in conjugation with visible light. The survival rate of P. gingivalis reached zero present when the suspension exposed to blue light-activated curcumin and hydrogen peroxide for 2 min. Besides, curcumin exerted a remarkable antibacterial activity against F. nucleatum in comparison with erythrosine and hydrogen peroxide (P=0.00). Furthermore, the bactericidal effect of visible light alone on P. gingivalis as black-pigmented bacteria was significant. Conclusion: Our result suggested that visible blue light in the presence of erythrosine, curcumin and hydrogen peroxide would be consider as a potential approach of PDT to kill the main gramnegative periodontal pathogens. From a clinical standpoint, this regimen could be established as an additional minimally invasive antibacterial treatment of plaque induced

  8. High-power-efficiency hybrid white organic light-emitting diodes with a single emitting layer doped with blue delayed fluorescent and yellow phosphorescent emitters

    International Nuclear Information System (INIS)

    High-efficiency hybrid white organic light-emitting diodes (HWOLEDs) with a blue thermally activated delayed fluorescent (TADF) emitter and a yellow phosphorescent emitter doped in a single emitting layer were developed. Exciton harvesting by the blue TADF and yellow phosphorescent emitters rendered both singlet and triplet excitons to contribute to the white emission, which leads to a high quantum efficiency of 22.4% and a power efficiency of 60.3 lm W−1 in the HWOLEDs. In addition, the electroluminescence spectra of the HWOLEDs were kept stable from 100 cd m−2 to 5, 000 cd m−2. (paper)

  9. Carrier Injection and Transport in Blue Phosphorescent Organic Light-Emitting Device with Oxadiazole Host

    Directory of Open Access Journals (Sweden)

    Tien-Lung Chiu

    2012-06-01

    Full Text Available In this paper, we investigate the carrier injection and transport characteristics in iridium(IIIbis[4,6-(di-fluorophenyl-pyridinato-N,C2']picolinate (FIrpic doped phosphorescent organic light-emitting devices (OLEDs with oxadiazole (OXD as the bipolar host material of the emitting layer (EML. When doping Firpic inside the OXD, the driving voltage of OLEDs greatly decreases because FIrpic dopants facilitate electron injection and electron transport from the electron-transporting layer (ETL into the EML. With increasing dopant concentration, the recombination zone shifts toward the anode side, analyzed with electroluminescence (EL spectra. Besides, EL redshifts were also observed with increasing driving voltage, which means the electron mobility is more sensitive to the electric field than the hole mobility. To further investigate carrier injection and transport characteristics, FIrpic was intentionally undoped at different positions inside the EML. When FIrpic was undoped close to the ETL, driving voltage increased significantly which proves the dopant-assisted-electron-injection characteristic in this OLED. When the undoped layer is near the electron blocking layer, the driving voltage is only slightly increased, but the current efficiency is greatly reduced because the main recombination zone was undoped. However, non-negligible FIrpic emission is still observed which means the recombination zone penetrates inside the EML due to certain hole-transporting characteristics of the OXD.

  10. Fluctuations of MS births and UV-light exposure

    NARCIS (Netherlands)

    Verheul, F.; Smolders, J.; Trojano, M.; Lepore, V.; Zwanikken, C.; Amato, M. P.; Grand'Maison, F.; Butzkueven, H.; Marrosu, M.; Duquette, P.; Comi, G.; Izquierdo, G.; Grammond, P.; Lus, G.; Petersen, T.; Bergamaschi, R.; Giuliani, G.; Boz, C.; Coniglio, G.; Van Pesch, V.; Lechner-Scott, J.; Cavalla, P.; Granella, F.; Avolio, C.; Fiol, M.; Poehlau, D.; Saladino, M. L.; Gallo, P.; Deri, N.; Oleschko Arruda, W.; Paine, M.; Ferro, M.; Barnett, M.; Cabrera-Gomez, J. A.; Slee, M.; Moore, F.; Shaw, C.; Petkovska-Boskova, T.; Rutherford, M.; Engelsen, O.; Damoiseaux, J.; Hupperts, R.

    2013-01-01

    Background Patients with multiple sclerosis (MS) are more frequently born in spring when compared to autumn. Fluctuation of UV-light has been hypothesized to drive this phenomenon. Aim To assess the correlation between fluctuation of sunlight and birth season in persons with MS. Methods For this rec

  11. Survival of Giardia lamblia trophozoites after exposure to UV light.

    Science.gov (United States)

    Li, Dong; Craik, Stephen A; Smith, Daniel W; Belosevic, Miodrag

    2008-01-01

    The ability of Giardia lamblia trophozoites to reproduce after exposure to different fluences of UV radiation was determined using an in vitro-cultured method. The rate of parasite reproduction following UV exposure was measured by direct enumeration of trophozoites cultured in Diamond's Trypticase Yeast extract-Iron (TYI)-S-33 medium. The results suggested that some G. lamblia trophozoites may survive or are reactivated following exposure to UV fluences up to 10 mJ cm(-2). In addition, trophozoites exposed to a UV fluence of 1 mJ cm(-2) were infectious to Mongolian gerbils. Evidence of survival or reactivation at UV fluences of 20 and 40 mJ cm(-2) was ambiguous and statistically inconclusive, while at 100 mJ cm(-2) there was no evidence of survival or reactivation. This finding may have implications for criteria used by the drinking water and wastewater treatment industry to ensure safe reduction of G. lamblia cysts by UV disinfection processes. PMID:17995955

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

    Science.gov (United States)

    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

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

    Science.gov (United States)

    Leong, Ta-Yan; Briggs, Winslow R.

    1982-01-01

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

  14. Rising CO2 and increased light exposure synergistically reduce marine primary productivity

    OpenAIRE

    Gao, Kunshan; Xu, Juntian; Gao, Guang; Li, Yahe; Hutchins, David A.; Huang, Bangqin; Wang, Lei; Zheng, Ying; Jin, Peng; Cai, Xiaoni; Häder, Donat-Peter; Li, Wei; Xu, Kai; Liu, Nana; Riebesell, Ulf

    2012-01-01

    Carbon dioxide and light are two major prerequisites of photosynthesis. Rising CO2 levels in oceanic surface waters in combination with ample light supply are therefore often considered stimulatory to marine primary production(1-3). Here we show that the combination of an increase in both CO2 and light exposure negatively impacts photosynthesis and growth of marine primary producers. When exposed to CO2 concentrations projected for the end of this century(4), natural phytoplankton assemblages...

  15. Interactions of Night Blue with Nucleic Acids and Determination of Nucleic Acids Using Resonance Light Scattering Technique

    Institute of Scientific and Technical Information of China (English)

    吴会灵; 梁宏; 等

    2003-01-01

    The noncovalent interactions of night blue (NB) with several nucleic acids in buffer medium of Britton-Robinson at pH 4.1 have been studied by spectroscopic methods.It is shown that the binding of NB with nucleic acids involves the J-aggregation of NB molecules on the surface of nucleic acids.The aggregation was encouraged by polyanions nucleic acids,in which nucleic acids served for acting templates,In this connection,a new method of nucleic acids with sensitivity at nanogram level is proposed based on the measurement of enhanced resonance light scattering (RLS).The linear range of ctDNA,fsDNA and yRNA is 0.01-2.5,0.03-2.5 and 0.04-1.0 μg/mL,respectively,and the corresponding detection limits(3σ)are 9.4,7.3 and 5.7ng/mL at 2.5×1005mol/L of NB.Synthetic and real samples were analyzed with satisfactory results.

  16. Highly efficient broad-area blue and white light-emitting diodes on bulk GaN substrates

    Energy Technology Data Exchange (ETDEWEB)

    Vampola, Kenneth J.; Fellows, Natalie N.; Masui, Hisashi; Chung, Roy B.; Sato, Hitoshi; Sonoda, Junichi; Hirasawa, Hirohiko; Iza, Michael; Nakamura, Shuji [Materials Department, University of California, Santa Barbara, California (United States); Brinkley, Stuart E.; Furukawa, Motoko [Electrical and Computer Engineering Department, University of California, Santa Barbara, California (United States); DenBaars, Steven P. [Materials Department, University of California, Santa Barbara, California (United States)]|[Electrical and Computer Engineering Department, University of California, Santa Barbara, California (United States)

    2009-02-15

    Highly efficient light emitting diodes (LEDs) with peak emission wavelengths of nominally 450 nm were grown, fabricated and tested. The growth was performed by metal organic chemical vapour deposition. The LEDs were grown on c-plane (0001) bulk GaN substrates and fabricated into broad-area devices with active area 0.01 cm{sup 2}. Considerations were made to improve extraction efficiency, including transparent contacts, suspended mirror-less packaging and encapsulation in a truncated pyramid optic. These factors resulted in LEDs with high peak external quantum efficiency and reduced efficiency droop. The output power and external quantum efficiency at 20 mA were 38.5 mW and 68.9%. At 100 mA, they were 170 mW and 60.9%. White LEDs were fabricated by application of a yellow phosphor to the blue LEDs. The white LED luminous flux and efficacy at 20 mA was 9.6 lm and 128 lm/W. The chromaticity coordinates and correlated colour temperature were (0.348 K, 0.378 K) and 4998 K. (copyright 2009 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  17. Photophysical study of blue-light excitable ternary Eu(III) complexes and their encapsulation into polystyrene nanoparticles

    International Nuclear Information System (INIS)

    In this work, 14 ternary Eu(III) complexes were studied by means of spectroscopy. The studied Eu(III) complexes consisted of Lewis bases (4′-(4-diethylaminophenyl)-2,2′:6′,2″-terpyridine (L8) or 1,10-phenanthroline (L9)) and differently substituted β-diketones. The ternary complexes with L8 show the excitation peak at 405 nm and the quantum yield even 76%. The brightest ternary complex at the 405 nm excitation was Eu(L3)3L8 while Eu(L7)3L8 (HL3=4,4,4-trifluoro-1-(2-thienyl)-1,3-butanedione, HL7=1-(9-ethyl-9H-carbazol-3-yl)-4,4,5,5,5-pentafluoro-1,3-pentanedione) was found to be the brightest at the ligand-centred excitation maximum. The ternary complexes were studied mainly in toluene as the model environment for the polystyrene nanoparticle cavities. The complexes were successfully loaded into the polystyrene nanoparticles enabling their bioanalytical application in aqueous environment. The encapsulation of the complexes preserved, or even enhanced, their good photophysical features. - Highlights: • Ternary Eu3+ complexes with some β-diketone and substituted terpyridine were studied. • Ternary complexes with substituted terpyridine showed blue-light excitability. • Ternary complexes were successfully loaded into the polystyrene nanoparticles. • Encapsulation of the complexes preserved their good photophysical features

  18. Band Gap Tuning of h-MoO3 Nanocrystals for Efficient Visible Light Photocatalytic Activity Against Methylene Blue Dye.

    Science.gov (United States)

    Chithambararaj, A; Winston, B; Sanjini, N S; Velmathi, S; Bose, A Chandra

    2015-07-01

    The photocatalytic degradation of methylene blue (MB) dye in aqueous solution was investigated using hexagonal molybdenum oxide (h-MoO3) nanocrystals under visible light irradiation. Chemical precipitation method was utilized to synthesize h-MoO3 and control over the crystal size, shape and distribution were characterized by using HNO3 and HCl as precipitating reagents. The photocatalysts were examined through X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM) and energy dispersive X-ray spectrum (EDX) for structural, functional, surface morphology and elemental analysis, respectively. The XRD results revealed that the samples were in single phase hexagonal crystal structure. XRD peak broadening analysis was used for crystallite size and strain estimation. The particles were anisotropic in nature and showed one dimensional (1-D) rod structure with hexagonal cross section. Further, the crystal phase stability, optical absorption and emission properties were studied by thermo gravimetric analysis (TGA), diffuse reflectance spectroscopy (DRS) and photoluminescence (PL) measurements, respectively. The photocatalytic results demonstrated that the photocatalytic activity of h-MoO3 synthesized using HCl was improved, in comparison to that of HNO3 utilized h-MoO3 sample. PMID:26373056

  19. Adjunctive dental therapy via tooth plaque reduction and gingivitis treatment by blue light-emitting diodes tooth brushing

    Science.gov (United States)

    Genina, Elina A.; Titorenko, Vladimir A.; Belikov, Andrey V.; Bashkatov, Alexey N.; Tuchin, Valery V.

    2015-12-01

    The efficacy of blue light-emitting toothbrushes (B-LETBs) (405 to 420 nm, power density 2 mW/cm2) for reduction of dental plaques and gingival inflammation has been evaluated. Microbiological study has shown the multifactor therapeutic action of the B-LETBs on oral pathological microflora: in addition to partial mechanical removal of bacteria, photodynamic action suppresses them up to 97.5%. In the pilot clinical studies, subjects with mild to moderate gingivitis have been randomly divided into two groups: a treatment group that used the B-LETBs and a control group that used standard toothbrushes. Indices of plaque, gingival bleeding, and inflammation have been evaluated. A significant improvement of all dental indices in comparison with the baseline (by 59%, 66%, and 82% for plaque, gingival bleeding, and inflammation, respectively) has been found. The treatment group has demonstrated up to 50% improvement relative to the control group. We have proposed the B-LETBs to serve for prevention of gingivitis or as an alternative to conventional antibiotic treatment of this disease due to their effectiveness and the absence of drug side effects and bacterial resistance.

  20. Acrodynia: exposure to mercury from fluorescent light bulbs

    Energy Technology Data Exchange (ETDEWEB)

    Tunnessen, W.W. Jr.; McMahon, K.J.; Baser, M.

    1987-05-01

    Medical attention was sought for a 23-month-old toddler because of anorexia, weight loss, irritability, profuse sweating, peeling and redness of his fingers and toes, and a miliarial rash. The diagnosis was mercury poisoning, and an investigation of his environment disclosed that he had been exposed to mercury from broken fluorescent light bulbs. Acrodynia resulting from fluorescent bulbs has not been previously reported.

  1. Ultrastructural pathogenesis of lesions produced by exposure to oxygen difluoride with correlative light microscopy

    Science.gov (United States)

    Harrison, G.; Mackenzie, W.

    1973-01-01

    The lungs of rats exposed to OF2 were examined by light and electron microscopy. The exposures were for 30 to 60 minutes to an average of 4.5 ppm OF2, the minimal lethal dose. Animals were sacrificed after 30 (group 1) and 60 minutes (group 2) exposure and 1 (group 3) and 2 (group 4) hours following 60 minutes exposure. Mild gross changes were observed in groups 3 and 4, but no light microscopic lesions were found. Alterations were noted in all four groups using electron microscopy. These were mostly indicative of fluid change and consisted of blebbing of the endothelial and epithelial layers of the alveolocapillary wall and rarification of the cytoplasm of these cells. The lamellar bodies of the Type II cells showed an increasing and consistent loss of matrix structure and density. These fine structural changes increased in quantity and severity as time of exposure or post-exposure period increased. (Modified author abstract)

  2. Association of Light Exposure on Physical Activity and Sedentary Time in Young People

    Directory of Open Access Journals (Sweden)

    Daniel Aggio

    2015-03-01

    Full Text Available Background: To investigate whether light exposure was associated with objectively measured physical activity (PA and sedentary behaviour in young people. Methods: Participants (n = 229, 46.7% female were young people (mean 8.8 years [SD ± 2.2] from the borough of Camden, UK. Daily sedentary time, moderate and vigorous PA (MVPA and light exposure were measured using a tri-axial accelerometer with an ambient light sensor during the summer. Multiple linear regression models examined associations between average daily light exposure, sedentary time and time in MVPA. Models were repeated investigating weekdays and weekend days separately. Analyses were adjusted for pre-specified covariables, including age, sex, device wear time, ethnic group, school and body fat. Results: There were significant associations between average daily light exposure and time sedentary (β coefficient = −11.2, 95% CI, −19.0 to −3.4 and in MVPA (β coefficient = 3.5, 95% CI, 1.2 to 5.9. Light exposure was significantly associated with weekend sedentary time (β coefficient = −10.0, 95% CI, −17.6, −2.4, weekend MVPA (β coefficient = 3.7, 95% CI, 1.7, 5.7, weekday sedentary time (β coefficient = −15.0, 95% CI, −22.7 to −7.2, but not weekday MVPA (β coefficient = 2.0, 95% CI, −0.5 to 4.5. Conclusion: Average daily light exposure is positively associated with time in MVPA and negatively associated with sedentary time. Increasing daylight exposure may be a useful intervention strategy for promoting physical activity.

  3. Acute short-term dim light exposure can lower muscle strength endurance

    Institute of Scientific and Technical Information of China (English)

    Arnold G. Nelson; Joke Kokkonen; Megan Mickenberg

    2015-01-01

    Background:Since it has been shown that spending 18 h under dim light conditions can result in reduced handgrip endurance, it was questioned whether or not a shorter exposure to dim light (i.e., 1 h) would have similar influence upon muscular endurance. Therefore this study compared the number of weighted knee extension lifts that could be done after spending 1 h in either dim or bright light. Methods:Participants (5 women, 11 men, college students 19-26 years) performed knee extension lifts to exhaustion with a load approximating 40%of their body weight. The lifts to exhaustion were measured immediately following 1 h of exposure to each of the following three con-ditions:dark (DL), room light (RL), and room light plus 5 mg melatonin (RLM). A minimum of 48 h separated each condition, and all par-ticipants started the exposures in a rested fed condition. Results:Average (±SD) number of knee extension lifts for RL (62.0 ± 22.0) was significantly ( p<0.05) greater than DL (51.4 ± 14.7) and RLM (57.8 ± 22.9). The number of RLM knee extension lifts was not significantly different from DL. Exposure to 1 h of dim light immediately prior to activity can result in a reduction in thigh muscle endurance. The decline in performance to short-term dim light exposure was similar to that found following longer-term exposure. Conclusion: It appears that light intensity can influence muscle endurance, however, at this time this effect cannot be directly related to endogenous melatonin production.

  4. Astrophotography on the go using short exposures with light mounts

    CERN Document Server

    Ashley, Joseph

    2015-01-01

    No longer are heavy, sturdy, expensive mounts and tripods required to photograph deep space. With today's advances in technology, all that is required is an entry-DSLR and an entry level GoTo telescope. Here is all of the information needed to start photographing the night sky without buying expensive tracking mounts. By using multiple short exposures and combining them with mostly ‘freeware’ computer programs, the effect of image rotation can be minimized to a point where it is undetectable in normal astrophotography, even for a deep-sky object such as a galaxy or nebula. All the processes, techniques, and equipment needed to use inexpensive, lightweight altazimuth and equatorial mounts and very short exposures photography to image deep space objects are explained, step-by-step, in full detail, supported by clear, easy to understand graphics and photographs.   Currently available lightweight mounts and tripods are identified and examined from an economic versus capability perspective to help users deter...

  5. Multiple experimental approaches of immunotoxic effects of mercury chloride in the blue mussel, Mytilus edulis, through in vivo, in tubo and in vitro exposures

    Energy Technology Data Exchange (ETDEWEB)

    Duchemin, Matthieu B. [Laboratoire des sciences de l' environnement marin, UMR CNRS 6539, Institut Universitaire Europeen de la Mer, Universite de Bretagne Occidentale, Place Nicolas Copernic, 29 280 Plouzane (France); INRS-Institut Armand-Frappier, 245 Hymus, Pointe-Claire, H9R 1G6 Quebec (Canada)], E-mail: matthieu.duchemin@univ-brest.fr; Auffret, Michel; Wessel, Nathalie [Laboratoire des sciences de l' environnement marin, UMR CNRS 6539, Institut Universitaire Europeen de la Mer, Universite de Bretagne Occidentale, Place Nicolas Copernic, 29 280 Plouzane (France); Fortier, Marlene; Morin, Yves [INRS-Institut Armand-Frappier, 245 Hymus, Pointe-Claire, H9R 1G6 Quebec (Canada); Pellerin, Jocelyne [Institut des Sciences de la Mer de Rimouski, Universite du Quebec a Rimouski, 310 Allee des Ursulines, Rimouski, G5L 3A1 Quebec (Canada); Fournier, Michel [INRS-Institut Armand-Frappier, 245 Hymus, Pointe-Claire, H9R 1G6 Quebec (Canada); Institut des Sciences de la Mer de Rimouski, Universite du Quebec a Rimouski, 310 Allee des Ursulines, Rimouski, G5L 3A1 Quebec (Canada)

    2008-05-15

    Biological impairments due to mercury discharge into the environment are now an issue of global concern. From the three forms of mercury found in aquatic ecosystems, the immunotoxic effects of mercury chloride were examined in the model animal, the blue mussel. In order to investigate the toxic potency of this chemical, three exposure regimes were carried out: chronic exposure of groups of individuals, a new protocol 'in tubo' designed for sub-acute exposures of individuals, and acute exposures of target cells. Chronic exposure revealed significant immunotoxic effects after 7 days at 10{sup -6} M, while acute exposures showed significant inhibition of phagocytosis at 10{sup -4} M and 10{sup -3} M. In sub-acute exposures both circulating haemocytes and haemocyte mortality increased at 10{sup -4} M and 10{sup -3} M while phagocytosis and the clearance rate drew hormetic toxic effects on healthy individuals. These results suggest the use of the 'in tubo' design for bivalve toxicological individual studies. - HgCl{sub 2} impairs the immune system of test-tube mussels.

  6. Multiple experimental approaches of immunotoxic effects of mercury chloride in the blue mussel, Mytilus edulis, through in vivo, in tubo and in vitro exposures

    International Nuclear Information System (INIS)

    Biological impairments due to mercury discharge into the environment are now an issue of global concern. From the three forms of mercury found in aquatic ecosystems, the immunotoxic effects of mercury chloride were examined in the model animal, the blue mussel. In order to investigate the toxic potency of this chemical, three exposure regimes were carried out: chronic exposure of groups of individuals, a new protocol 'in tubo' designed for sub-acute exposures of individuals, and acute exposures of target cells. Chronic exposure revealed significant immunotoxic effects after 7 days at 10-6 M, while acute exposures showed significant inhibition of phagocytosis at 10-4 M and 10-3 M. In sub-acute exposures both circulating haemocytes and haemocyte mortality increased at 10-4 M and 10-3 M while phagocytosis and the clearance rate drew hormetic toxic effects on healthy individuals. These results suggest the use of the 'in tubo' design for bivalve toxicological individual studies. - HgCl2 impairs the immune system of test-tube mussels

  7. Highly Improved Efficiency of Deep-Blue Fluorescent Polymer Light-Emitting Device Based on a Novel Hole Interface Modifier with 1,3,5-Triazine Core.

    Science.gov (United States)

    Xia, Lianpeng; Xue, Yuyuan; Xiong, Kang; Cai, Chaosheng; Peng, Zuosheng; Wu, Ying; Li, Yuan; Miao, Jingsheng; Chen, Dongcheng; Hu, Zhanhao; Wang, Jianbin; Peng, Xiaobin; Mo, Yueqi; Hou, Lintao

    2015-12-01

    We present an investigation of deep-blue fluorescent polymer light-emitting diodes (PLEDs) with a novel functional 1,3,5-triazine core material (HQTZ) sandwiched between poly(3,4-ethylene dioxythiophene):poly(styrene sulfonic acid) layer and poly(vinylcarbazole) layer as a hole injection layer (HIL) without interface intermixing. Ultraviolet photoemission spectroscopy and Kelvin probe measurements were carried out to determine the change of anode work function influenced by the HQTZ modifier. The thin HQTZ layer can efficiently maximize the charge injection from anode to blue emitter and simultaneously enhance the hole mobility of HILs. The deep-blue device performance is remarkably improved with the maximum luminous efficiency of 4.50 cd/A enhanced by 80% and the maximum quantum efficiency of 4.93%, which is 1.8-fold higher than that of the conventional device without HQTZ layer, including a lower turn-on voltage of 3.7 V and comparable Commission Internationale de L'Eclairage coordinates of (0.16, 0.09). It is the highest efficiency ever reported to date for solution-processed deep-blue PLEDs based on the device structure of ITO/HILs/poly(9,9-dialkoxyphenyl-2,7-silafluorene)/CsF/AL. The results indicate that HQTZ based on 1,3,5-triazine core can be a promising candidate of interfacial materials for deep-blue fluorescent PLEDs. PMID:26422296

  8. Efficient KTiOPO4 blue-light converter for monochromatic 1.3188-μm emission line of pulsed Nd:YAG laser

    Science.gov (United States)

    Mu, Xiaodong; Shi, Wei; Ding, Yujie J.

    2003-06-01

    A frequency converter is designed for producing efficient blue light at 0.4396 μm from a monochromatic, pulsed, 1.3188-μm Nd-doped emission line by quasi-phase-matched (QPM) second-harmonic generation (SHG), followed by sum-frequency generation, in an integrated, periodically poled KTiOPO4 (KTP) and monodomain KTP crystal. An average 55-mW (peak power of 43.0 W) blue light is achieved by us for an average 2.5-W (peak power of 2.0 kW) pump power; the overall conversion efficiency is thus 2.2%. Through polarization optimization, the same device produces an average 435 mW (peak power of 339.8 W) for the red light through QPM SHG, with a corresponding conversion efficiency of 16%. As a practical blue-light converter, the angle- and temperature-tuning characteristics and period tolerance have been fully investigated.

  9. Quinoline-Substituted 10-(naphthalene-7-yl)anthracene Derivatives for Blue Fluorescent Organic Light-Emitting Diodes.

    Science.gov (United States)

    Kim, Chanwoo; Park, Soo Na; Lee, Seul Bee; Kim, Young Seok; Lee, Ho Won; Kim, Young Kwan; Yoon, Seung Soo

    2016-02-01

    In this study, we have designed and synthesized blue emitters based on quinoline-substituted 10-(naphthalene-7-yl)anthracene. Particularly, a material exhibited highly efficient blue electroluminescence with CIE coordinates of (0.15, 0.18). PMID:27433688

  10. Global Trends in Exposure to Light Pollution in Natural Terrestrial Ecosystems

    Directory of Open Access Journals (Sweden)

    Jonathan Bennie

    2015-03-01

    Full Text Available The rapid growth in electric light usage across the globe has led to increasing presence of artificial light in natural and semi-natural ecosystems at night. This occurs both due to direct illumination and skyglow - scattered light in the atmosphere. There is increasing concern about the effects of artificial light on biological processes, biodiversity and the functioning of ecosystems. We combine intercalibrated Defense Meteorological Satellite Program’s Operational Linescan System (DMSP/OLS images of stable night-time lights for the period 1992 to 2012 with a remotely sensed landcover product (GLC2000 to assess recent changes in exposure to artificial light at night in 43 global ecosystem types. We find that Mediterranean-climate ecosystems have experienced the greatest increases in exposure, followed by temperate ecosystems. Boreal, Arctic and montane systems experienced the lowest increases. In tropical and subtropical regions, the greatest increases are in mangroves and subtropical needleleaf and mixed forests, and in arid regions increases are mainly in forest and agricultural areas. The global ecosystems experiencing the greatest increase in exposure to artificial light are already localized and fragmented, and often of particular conservation importance due to high levels of diversity, endemism and rarity. Night time remote sensing can play a key role in identifying the extent to which natural ecosystems are exposed to light pollution.

  11. High efficiency and broadband blue-emitting NaCaBO{sub 3}: Ce{sup 3+} phosphor for NUV light-emitting diodes

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Xinguo, E-mail: mpcc1@qq.com [Ministry–Province Jointly Constructed Cultivation Base for State Key Laboratory for Processing Non-Ferrous Metal and Featured Materials, Guangxi, Zhuang Autonomous Region, Guangxi University, Nanning 530004 (China); School of Chemistry and Chemical Engineering, Guangxi University, Nanning 530004 (China); State Key Laboratory of Optoelectronic Materials and Technologies, School of Chemistry and Chemical Engineering, Sun Yat-Sen University, Guangzhou 510275 (China); Song, Jiahui; Zhou, Chunyan; Zhou, Liya [Ministry–Province Jointly Constructed Cultivation Base for State Key Laboratory for Processing Non-Ferrous Metal and Featured Materials, Guangxi, Zhuang Autonomous Region, Guangxi University, Nanning 530004 (China); School of Chemistry and Chemical Engineering, Guangxi University, Nanning 530004 (China); Gong, Menglian [State Key Laboratory of Optoelectronic Materials and Technologies, School of Chemistry and Chemical Engineering, Sun Yat-Sen University, Guangzhou 510275 (China)

    2014-05-01

    A blue-emitting phosphor, NaCaBO{sub 3}: Ce{sup 3+}, was synthesized by a solid-state reaction. The phosphor can be efficiently excited by near ultraviolet (NUV) light, and emits bright broadband blue light. The optimal Ce{sup 3+} concentration and its critical energy transfer distance were determined to be 0.01 and 38.0 Å. The photoluminescence excitation (PLE), emission (PL) spectra, and decay curves were measured to analyze the crystallographic occupancy sites of Ce{sup 3+} in the NaCaBO{sub 3} hosts. The composition-optimized NaCaBO{sub 3}: 0.01Ce{sup 3+} exhibited high quantum efficiency of 75%. The results indicate that the phosphor NaCaBO{sub 3}: Ce{sup 3+} could be served as a potential blue-emitting phosphor candidate for NUV LED application. - Highlights: • A high efficiency and broadband blue-emitting phosphor, NaCaBO{sub 3}: Ce{sup 3+}, was synthesized by a solid-state reaction. • The crystallographic site of Ce{sup 3+} ion in the LiCaPO{sub 4} lattice was identified as 7-fold and 6-fold Ca{sup 2+} site. • The phosphor exhibits high quantum efficiency of 75% and good thermal stability.

  12. Residential exposure to visible blue space (but not green space) associated with lower psychological distress in a capital city.

    Science.gov (United States)

    Nutsford, Daniel; Pearson, Amber L; Kingham, Simon; Reitsma, Femke

    2016-05-01

    As urbanisation escalates globally, urban neighbourhood features which may improve physical and mental health are of growing importance. Using a cross-sectional survey of adults and the application of novel geospatial techniques, this study investigated whether increased visibility of nature (green and blue space) was associated with lower psychological distress (K10 scores), in the capital city of Wellington, New Zealand. To validate, we also tested whether visibility of blue space was associated missing teeth in the same sample. Cluster robust, linear regression models were fitted to test the association between visibility of nature and K10 scores, adjusted for age, sex, personal income, neighbourhood population density, housing quality, crime and deprivation. Higher levels of blue space visibility were associated with lower psychological distress (β=-0.28, p<0.001). Importantly, blue space visibility was not significantly associated with tooth loss. Further research is needed to confirm whether increased visibility of blue space could promote mental well-being and reduce distress in other cities. PMID:26974233

  13. Evening exposure to a light-emitting diodes (LED)-backlit computer screen affects circadian physiology and cognitive performance.

    Science.gov (United States)

    Cajochen, Christian; Frey, Sylvia; Anders, Doreen; Späti, Jakub; Bues, Matthias; Pross, Achim; Mager, Ralph; Wirz-Justice, Anna; Stefani, Oliver

    2011-05-01

    Many people spend an increasing amount of time in front of computer screens equipped with light-emitting diodes (LED) with a short wavelength (blue range). Thus we investigated the repercussions on melatonin (a marker of the circadian clock), alertness, and cognitive performance levels in 13 young male volunteers under controlled laboratory conditions in a balanced crossover design. A 5-h evening exposure to a white LED-backlit screen with more than twice as much 464 nm light emission {irradiance of 0,241 Watt/(steradian × m(2)) [W/(sr × m(2))], 2.1 × 10(13) photons/(cm(2) × s), in the wavelength range of 454 and 474 nm} than a white non-LED-backlit screen [irradiance of 0,099 W/(sr × m(2)), 0.7 × 10(13) photons/(cm(2) × s), in the wavelength range of 454 and 474 nm] elicited a significant suppression of the evening rise in endogenous melatonin and subjective as well as objective sleepiness, as indexed by a reduced incidence of slow eye movements and EEG low-frequency activity (1-7 Hz) in frontal brain regions. Concomitantly, sustained attention, as determined by the GO/NOGO task; working memory/attention, as assessed by "explicit timing"; and declarative memory performance in a word-learning paradigm were significantly enhanced in the LED-backlit screen compared with the non-LED condition. Screen quality and visual comfort were rated the same in both screen conditions, whereas the non-LED screen tended to be considered brighter. Our data indicate that the spectral profile of light emitted by computer screens impacts on circadian physiology, alertness, and cognitive performance levels. The challenge will be to design a computer screen with a spectral profile that can be individually programmed to add timed, essential light information to the circadian system in humans. PMID:21415172

  14. Cloning and characterization of the BLR2, the homologue of the blue-light regulator of Neurospora crassa WC-2, in the phytopathogenic fungus Bipolaris oryzae.

    Science.gov (United States)

    Moriwaki, Akihiro; Katsube, Hirofumi; Ueno, Makoto; Arase, Sakae; Kihara, Junichi

    2008-02-01

    Bipolaris oryzae is a filamentous ascomycetous fungus that causes brown leaf spot disease in rice. We isolated and characterized BLR2, a gene that encodes a putative blue-light regulator similar to Neurospora crassa white collar-2 (WC-2). The deduced amino acid sequence of the BLR2 showed significant homology to other fungal blue-light regulator proteins in the Per-Arnt-Sim (PAS) protein-protein interaction domain, nuclear localization signal, and GATA zinc finger DNA-binding domains. The BLR2-silenced transformants hardly produced conidia in the subsequent dark condition after near-ultraviolet (NUV) irradiation. Furthermore, the BLR2-silenced transformants suppressed the photolyase (PHR1) gene expression enhanced by NUV irradiation. These results indicate that BLR2 is necessary not only for conidial formation, but also for NUV radiation-enhanced photolyase gene expression in B. oryzae. PMID:18172720

  15. Blue light emission from a glass/liquid interface for real-time monitoring of a laser-induced etching process

    International Nuclear Information System (INIS)

    An organic dye, Oil-Red-O, dissolved in p-xylene was used for laser-induced backside wet etching using a visible laser (visible-LIBWE) for the first time. Blue light (360–500 nm) emission from the glass/liquid interface was observed during the etching of borosilicate glass using a nanosecond Q-switched green laser. The emission was confirmed to accompany the etching process. The UV–visible spectrum consists of characteristic peaks of metals, which are the components of the glass. The maximal emission intensity occurs when the laser focusing is at the glass/liquid interface. The etching threshold measured by observing the blue light emission is comparable to that determined by the traditional method. We concluded that the emission is the plasma emission of the etched glass. By measuring the plasma emission, the occurrence of the etching and the crack formation in the glass can be monitored in real time

  16. White organic light-emitting devices based on blue fluorescent dye combined with dual sub-monolayer

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Huishan, E-mail: yanghuishan1697@163.com

    2013-10-15

    White organic light-emitting devices have been realized by using highly blue fluorescent dye 4,4′-Bis(2,2-diphenyl-ethen-1-yl)-4,4′-di-(tert-butyl)phenyl(p-TDPVBi) and [2-methyl-6-[2-(2, 3,6,7-tetrahydro-1H, red fluorescent dye 5H-benzo[ij] quinolizin-9-yl) ethenyl]-4H-pyran-4-ylidene] propane-dinitrile(DCM2), together with well known green fluorescent dye quinacridone (QAD). The fabrication of multilayer WOLEDs did not involve the hard-to-control doping process. The structure of the device is ITO/m-MTDATA (45 nm)/NPB(8 nm)/p-TDPVBi(15 nm)/DCM2(x nm)/Alq{sub 3} (5 nm)/QAD(y nm)/Alq{sub 3}(55 nm)/LiF(1 nm)/Al, where 4,4′,4′′-tris{N,-(3-methylphenyl)-N-phenylamine}triphenylamine (m-MTDATA) acts as a hole injection layer, N,N′-bis-(1-naphthyl)-N, N′-diphenyl-1, 1′-biph-enyl-4, 4′-diamine (NPB) acts as a hole transport layer, p-TDPVBi acts as a blue emitting layer, DCM2 acts as a red emitting layer, QAD acts as a green emitting layer, tris-(8-hydroxyquinoline) aluminum (Alq{sub 3}) acts as an electron transport layer, and WOLEDs of devices A, B, C and D are different in layer thickness of DCM2 and QAD, respectively. To change the thickness of dual sub-monolayer DCM2 and QAD, the WOLEDs were obtained. When x, y=0.05, 0.1, the Commission Internationale de 1’Eclairage (CIE) coordinates of the device change from (0.4458, 0.4589) at 3 V to (0.3137, 0.3455) at 12 V that are well in the white region, and the color temperature and color rendering index were 5348 K and 85 at 8 V, respectively. Its maximum luminance was 35260 cd/m{sup 2} at 12 V, and maximum current efficiency and maximum power efficiency were 13.54 cd/A at 12 V and 6.68 lm/W at 5 V, respectively. Moreover, the current efficiency is largely insensitive to the applied voltage. The electroluminescence intensity of white EL devices varied only little at deferent dual sub-monolayer. Device D exhibited relatively high color rendering index (CRI) in the range of 88–90, which was essentially

  17. White organic light-emitting devices based on blue fluorescent dye combined with dual sub-monolayer

    International Nuclear Information System (INIS)

    White organic light-emitting devices have been realized by using highly blue fluorescent dye 4,4′-Bis(2,2-diphenyl-ethen-1-yl)-4,4′-di-(tert-butyl)phenyl(p-TDPVBi) and [2-methyl-6-[2-(2, 3,6,7-tetrahydro-1H, red fluorescent dye 5H-benzo[ij] quinolizin-9-yl) ethenyl]-4H-pyran-4-ylidene] propane-dinitrile(DCM2), together with well known green fluorescent dye quinacridone (QAD). The fabrication of multilayer WOLEDs did not involve the hard-to-control doping process. The structure of the device is ITO/m-MTDATA (45 nm)/NPB(8 nm)/p-TDPVBi(15 nm)/DCM2(x nm)/Alq3 (5 nm)/QAD(y nm)/Alq3(55 nm)/LiF(1 nm)/Al, where 4,4′,4′′-tris{N,-(3-methylphenyl)-N-phenylamine}triphenylamine (m-MTDATA) acts as a hole injection layer, N,N′-bis-(1-naphthyl)-N, N′-diphenyl-1, 1′-biph-enyl-4, 4′-diamine (NPB) acts as a hole transport layer, p-TDPVBi acts as a blue emitting layer, DCM2 acts as a red emitting layer, QAD acts as a green emitting layer, tris-(8-hydroxyquinoline) aluminum (Alq3) acts as an electron transport layer, and WOLEDs of devices A, B, C and D are different in layer thickness of DCM2 and QAD, respectively. To change the thickness of dual sub-monolayer DCM2 and QAD, the WOLEDs were obtained. When x, y=0.05, 0.1, the Commission Internationale de 1’Eclairage (CIE) coordinates of the device change from (0.4458, 0.4589) at 3 V to (0.3137, 0.3455) at 12 V that are well in the white region, and the color temperature and color rendering index were 5348 K and 85 at 8 V, respectively. Its maximum luminance was 35260 cd/m2 at 12 V, and maximum current efficiency and maximum power efficiency were 13.54 cd/A at 12 V and 6.68 lm/W at 5 V, respectively. Moreover, the current efficiency is largely insensitive to the applied voltage. The electroluminescence intensity of white EL devices varied only little at deferent dual sub-monolayer. Device D exhibited relatively high color rendering index (CRI) in the range of 88–90, which was essentially voltage

  18. Blue gods, blue oil, and blue people.

    Science.gov (United States)

    Fairbanks, V F

    1994-09-01

    Studies of the composition of coal tar, which began in Prussia in 1834, profoundly affected the economies of Germany, Great Britain, India, and the rest of the world, as well as medicine and surgery. Such effects include the collapse of the profits of the British indigo monopoly, the growth in economic power of Germany based on coal tar chemistry, and an economic crisis in India that led to more humane tax laws and, ultimately, the independence of India and the end of the British Empire. Additional consequences were the development of antiseptic surgery and the synthesis of a wide variety of useful drugs that have eradicated infections and alleviated pain. Many of these drugs, particularly the commonly used analgesics, sulfonamides, sulfones, and local anesthetics, are derivatives of aniline, originally called "blue oil" or "kyanol." Some of these aniline derivatives, however, have also caused aplastic anemia, agranulocytosis, and methemoglobinemia (that is, "blue people"). Exposure to aniline drugs, particularly when two or three aniline drugs are taken concurrently, seems to be the commonest cause of methemoglobinemia today. PMID:8065194

  19. Noncritically phase-matched second harmonic generation of blue light in Si[O]N-calix[4] arene slab type waveguides

    NARCIS (Netherlands)

    Wörhoff, K.; Noordman, O.F.J.; Lambeck, P.V.; Hulst, van N.F.; Albers, H.

    1996-01-01

    Phase-matching (TM(0)(omega) --> TM(1)(2 omega)) devices for generation of blue light using Si[0]N and optically nonlinear calix[4]arene layers are designed, fabricated and tested. The devices show second harmonic peak power of 17 mW at 472.9 nm and 4.5 W at 481.6 nm after 10 mm propagation length o

  20. Photophysical study of blue-light excitable ternary Eu(III) complexes and their encapsulation into polystyrene nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Räsänen, Markus, E-mail: mpvras@utu.fi [Department of Chemistry, University of Turku, FIN-20014 Turku (Finland); Takalo, Harri [DHR Finland Oy, Innotrac Diagnostics, Biolinja 12, FIN-20750 Turku (Finland); Soukka, Tero [Department of Biochemistry/Biotechnology, University of Turku, FIN-20014 Turku (Finland); Haapakka, Keijo; Kankare, Jouko [Department of Chemistry, University of Turku, FIN-20014 Turku (Finland)

    2015-04-15

    In this work, 14 ternary Eu(III) complexes were studied by means of spectroscopy. The studied Eu(III) complexes consisted of Lewis bases (4′-(4-diethylaminophenyl)-2,2′:6′,2″-terpyridine (L{sup 8}) or 1,10-phenanthroline (L{sup 9})) and differently substituted β-diketones. The ternary complexes with L{sup 8} show the excitation peak at 405 nm and the quantum yield even 76%. The brightest ternary complex at the 405 nm excitation was Eu(L{sup 3}){sub 3}L{sup 8} while Eu(L{sup 7}){sub 3}L{sup 8} (HL{sup 3}=4,4,4-trifluoro-1-(2-thienyl)-1,3-butanedione, HL{sup 7}=1-(9-ethyl-9H-carbazol-3-yl)-4,4,5,5,5-pentafluoro-1,3-pentanedione) was found to be the brightest at the ligand-centred excitation maximum. The ternary complexes were studied mainly in toluene as the model environment for the polystyrene nanoparticle cavities. The complexes were successfully loaded into the polystyrene nanoparticles enabling their bioanalytical application in aqueous environment. The encapsulation of the complexes preserved, or even enhanced, their good photophysical features. - Highlights: • Ternary Eu{sup 3+} complexes with some β-diketone and substituted terpyridine were studied. • Ternary complexes with substituted terpyridine showed blue-light excitability. • Ternary complexes were successfully loaded into the polystyrene nanoparticles. • Encapsulation of the complexes preserved their good photophysical features.

  1. Phase-shifting human circadian rhythms: influence of sleep timing, social contact and light exposure

    Science.gov (United States)

    Duffy, J. F.; Kronauer, R. E.; Czeisler, C. A.

    1996-01-01

    1. Both the timing of behavioural events (activity, sleep and social interactions) and the environmental light-dark cycle have been reported to contribute to entrainment of human circadian rhythms to the 24 h day. Yet, the relative contribution of those putative behavioural synchronizers to that of light exposure remains unclear. 2. To investigate this, we inverted the schedule of rest, sedentary activity and social contact of thirty-two young men either with or without exposure to bright light. 3. On this inverted schedule, the endogenous component of the core temperature rhythm of subjects who were exposed to bright light showed a significant phase shift, demonstrating that they were adapting to the new schedule. In contrast, the core temperature rhythm of subjects who were not exposed to bright light moved on average 0.2 h later per day and after 10 days had not significantly adapted to the new schedule. 4. The direction of phase shift in the groups exposed to bright light was dependent on the time of bright light exposure, while control subjects drifted to a later hour regardless of the timing of their schedule of sleep timing, social contact and meals. 5. These results support the concept that the light-dark cycle is the most important synchronizer of the human circadian system. They suggest that inversion of the sleep-wake, rest-activity and social contact cycles provides relatively minimal drive for resetting the human circadian pacemaker. 6. These data indicate that interventions designed to phase shift human circadian rhythms for adjustment to time zone changes or altered work schedules should focus on properly timed light exposure.

  2. Characterization of a rapid, blue light-mediated change in detectable phosphorylation of a plasma membrane protein from etiolated pea (Pisum sativum L. ) seedlings

    Energy Technology Data Exchange (ETDEWEB)

    Short, T.W.; Briggs, W.R. (Stanford Univ., CA (USA))

    1990-01-01

    When crude microsomal membranes from apical stem segments of etiolated Pisum sativum L. cv Alaska are mixed in vitro with {gamma}-({sup 32}P)ATP, a phosphorylated band of apparent molecular mass 120 kilodaltons can be detected on autoradiographs of sodium dodecyl sulfate electrophoresis gels. If the stem sections are exposed to blue light immediately prior to membrane isolation, this band is not evident. Comparisons of the kinetics, tissue distribution, and dark recovery of the phosphorylation response with those published for blue light mediated phototropism or rapid growth inhibition indicate that the phosphorylation could be linked to one or both of the reactions described. However, the fluence-response relationships for the change in detectable phosphorylation match quite closely those reported for phototropism but not those for growth inhibition. Blue light has also been found to regulate the capacity for in vitro phosphorylation of a second protein. It has an apparent molecular mass of 84 kilodaltons and is localized primarily in basal stem sections.

  3. Characterization of a rapid, blue light-mediated change in detectable phosphorylation of a plasma membrane protein from etiolated pea (Pisum sativum L.) seedlings

    International Nuclear Information System (INIS)

    When crude microsomal membranes from apical stem segments of etiolated Pisum sativum L. cv Alaska are mixed in vitro with γ-[32P]ATP, a phosphorylated band of apparent molecular mass 120 kilodaltons can be detected on autoradiographs of sodium dodecyl sulfate electrophoresis gels. If the stem sections are exposed to blue light immediately prior to membrane isolation, this band is not evident. Comparisons of the kinetics, tissue distribution, and dark recovery of the phosphorylation response with those published for blue light mediated phototropism or rapid growth inhibition indicate that the phosphorylation could be linked to one or both of the reactions described. However, the fluence-response relationships for the change in detectable phosphorylation match quite closely those reported for phototropism but not those for growth inhibition. Blue light has also been found to regulate the capacity for in vitro phosphorylation of a second protein. It has an apparent molecular mass of 84 kilodaltons and is localized primarily in basal stem sections

  4. [The effect of monochromatic light on the extracellular excretion of glycolate and the photorespiration in the blue-green alga Anacystis nidulans].

    Science.gov (United States)

    Döhler, G; Koch, R

    1972-12-01

    The algae were grown under normal air conditions in a low light intensity (400 lux) and measured in the normal CO2-concentration (0.03 Vol. %). After an illumination period we observed a CO2 gush which is dependent on the temperature and wavelength used during the measurements. At +20°C a CO2 gush occurs only in the blue and far red regions. At +35°C, on the other hand, a CO2 outburst appears over the whole spectrum. The magnitude of the CO2 gush varies with the wavelength used during the light period. On this basis we have measured an action spectrum of photorespiration which is identical with the action spectrum of photosynthetic CO2 uptake.Only at a low temperature (+20°C) and illumination with red light (550 to 651 nm; 10(-s) einsteins/cm(2)·sec) did we find a light induced release of glycolate; in blue (432 and 473 nm; 10(-s) einsteins/cm(2)·sec) and far red light (681 and 703 nm; 10(-8) einsteins/cm(2)·sec) no glycolate excretion occurred. But after addition of α-hydroxy-2-pyridylmethane sulfonate (10(-3)M) glycolate was excreted during illumination with all used wavelengths. The magnitude of glycolate production was nearly the same in all cases. No glycolate excretion occurred at +35°C in the whole region of the spectrum. Here, too, the addition of α-HPMS forced release of glycolate in all wavelengths, indicating that glycolate biosynthesis was occurring.The results are discussed with reference to the physiological behaviour of the algae and activation of photorespiration in blue light. The obtained action spectrum of photorespiration is explained on the basis of a close relationship to photosynthesis. PMID:24477848

  5. Untargeted Metabolomics Reveals Predominant Alterations in Lipid Metabolism Following Light Exposure in Broccoli Sprouts

    Directory of Open Access Journals (Sweden)

    Mariateresa Maldini

    2015-06-01

    Full Text Available The consumption of vegetables belonging to the family Brassicaceae (e.g., broccoli and cauliflower is linked to a reduced incidence of cancer and cardiovascular diseases. The molecular composition of such plants is strongly affected by growing conditions. Here we developed an unbiased metabolomics approach to investigate the effect of light and dark exposure on the metabolome of broccoli sprouts and we applied such an approach to provide a bird’s-eye view of the overall metabolic response after light exposure. Broccoli seeds were germinated and grown hydroponically for five days in total darkness or with a light/dark photoperiod (16 h light/8 h dark cycle. We used an ultra-performance liquid-chromatography system coupled to an ion-mobility, time-of-flight mass spectrometer to profile the large array of metabolites present in the sprouts. Differences at the metabolite level between groups were analyzed using multivariate statistical analyses, including principal component analysis and correlation analysis. Altered metabolites were identified by searching publicly available and in-house databases. Metabolite pathway analyses were used to support the identification of subtle but significant changes among groups of related metabolites that may have gone unnoticed with conventional approaches. Besides the chlorophyll pathway, light exposure activated the biosynthesis and metabolism of sterol lipids, prenol lipids, and polyunsaturated lipids, which are essential for the photosynthetic machinery. Our results also revealed that light exposure increased the levels of polyketides, including flavonoids, and oxylipins, which play essential roles in the plant’s developmental processes and defense mechanism against herbivores. This study highlights the significant contribution of light exposure to the ultimate metabolic phenotype, which might affect the cellular physiology and nutritional value of broccoli sprouts. Furthermore, this study highlights the

  6. Exposure of fluid milk to LED light negatively affects consumer perception and alters underlying sensory properties.

    Science.gov (United States)

    Martin, Nicole; Carey, Nancy; Murphy, Steven; Kent, David; Bang, Jae; Stubbs, Tim; Wiedmann, Martin; Dando, Robin

    2016-06-01

    Fluid milk consumption per capita in the United States has been steadily declining since the 1940s. Many factors have contributed to this decline, including the increasing consumption of carbonated beverages and bottled water. To meet the challenge of stemming the decline in consumption of fluid milk, the dairy industry must take a systematic approach to identifying and correcting for factors that negatively affect consumers' perception of fluid milk quality. To that end, samples of fluid milk were evaluated to identify factors, with a particular focus on light-emitting diode (LED) light exposure, which negatively affect the perceived sensory quality of milk, and to quantify their relative effect on the consumer's experience. Fluid milk samples were sourced from 3 processing facilities with varying microbial postprocessing contamination patterns based on historical testing. The effect of fat content, light exposure, age, and microbiological content were assayed across 23 samples of fluid milk, via consumer, descriptive sensory, and instrumental analyses. Most notably, light exposure resulted in a broad negative reaction from consumers, more so than samples with microbiological contamination exceeding 20,000 cfu/mL on days approaching code. The predominant implication of the study is that a component of paramount importance in ensuring the success of the dairy industry would be to protect fluid milk from all sources of light exposure, from processing plant to consumer. PMID:27060830

  7. Synthesis and Characterization of High Efficiency and Stable Spherical Ag3PO4 Visible Light Photocatalyst for the Degradation of Methylene Blue Solutions

    Directory of Open Access Journals (Sweden)

    Liqin Qin

    2015-01-01

    Full Text Available A facile method for the synthesis of Ag3PO4 visible light photocatalyst has been developed to improve the photocatalytic activity and stability. The as-prepared samples are investigated by X-ray powder diffraction, scanning electron microscopy, infrared spectroscopy, photoluminescence (PL spectroscopy, and UV-Vis diffuse reflectance spectroscopy techniques. The results reveal that the prepared Ag3PO4 has cube structure with a band gap of 2.26 eV. The as-prepared samples show higher photocatalytic activity for methylene blue (MB degradation than that of N-TiO2 under visible light irradiation.

  8. Effects of Exposure to Intermittent versus Continuous Red Light on Human Circadian Rhythms, Melatonin Suppression, and Pupillary Constriction

    OpenAIRE

    Ho Mien, Ivan; Chua, Eric Chern-Pin; Lau, Pauline; Tan, Luuan-Chin; Lee, Ivan Tian-Guang; Yeo, Sing-Chen; Tan, Sara Shuhui; Gooley, Joshua J.

    2014-01-01

    Exposure to light is a major determinant of sleep timing and hormonal rhythms. The role of retinal cones in regulating circadian physiology remains unclear, however, as most studies have used light exposures that also activate the photopigment melanopsin. Here, we tested the hypothesis that exposure to alternating red light and darkness can enhance circadian resetting responses in humans by repeatedly activating cone photoreceptors. In a between-subjects study, healthy volunteers (n = 24, 21–...

  9. Effects of Exposure to Intermittent versus Continuous Red Light on Human Circadian Rhythms, Melatonin Suppression, and Pupillary Constriction

    OpenAIRE

    Ho Mien, Ivan; Chua, Eric Chern-Pin; Lau, Pauline; Tan, Luuan-Chin; Lee, Ivan Tian-Guang; Yeo, Sing-Chen; Tan, Sara Shuhui; Gooley, Joshua J.

    2014-01-01

    Exposure to light is a major determinant of sleep timing and hormonal rhythms. The role of retinal cones in regulating circadian physiology remains unclear, however, as most studies have used light exposures that also activate the photopigment melanopsin. Here, we tested the hypothesis that exposure to alternating red light and darkness can enhance circadian resetting responses in humans by repeatedly activating cone photoreceptors. In a between-subjects study, healthy volunteers (n = 24, 21–...

  10. Postpartum Blues

    Medline Plus

    Full Text Available ... blues The postpartum blues E-mail to a friend Please fill in all fields. Please enter a ... blues: Talk to your partner or a good friend about how you feel Get plenty of rest ...

  11. Effect of ambient light exposure of media and embryos on development and quality of porcine parthenogenetically activated embryos

    DEFF Research Database (Denmark)

    Li, Rong; Liu, Ying; Callesen, Henrik

    2015-01-01

    tested in two experiments: (1) ambient light on medium subsequently used for embryo in vitro development; and (2) ambient light exposure on activated oocytes before in vitro development. The results from Experiment 1 showed that exposure of culture medium to both types of ambient light decreased the....... In conclusion, exposure to ambient light can be harmful to embryo development, both when medium is exposed for a long period of time and, to a greater extent, when the embryo itself is exposed for >1 h. In practice, it is therefore recommended to protect both culture medium and porcine embryos......Light exposure is a common stress factor during in vitro handling of oocytes and embryos that originates from both microscope and ambient light. In the current study, the effect of two types of ambient light (daylight and laboratory light) on porcine parthenogenetically activated (PA) embryos was...

  12. Presumed corneal intraepithelial neoplasia associated with contact lens wear and intense ultraviolet light exposure.

    OpenAIRE

    Guex-Crosier, Y.; Herbort, C P

    1993-01-01

    Corneal intraepithelial neoplasia (CIN) is a rare dysplastic process affecting mostly elderly fair-skinned people. A variant of the disease associated with contact lens wear was recently described. The three cases reported here had a history of contact lens wear together with strong ultraviolet light exposure. These two conditions may represent a serious risk factor for the development of CIN.

  13. Blue and Green light InGaN/GaN Multiquantum-Well grown by plasma-assisted molecular beam epitaxy

    Science.gov (United States)

    Hu, Chia-Hsuan; Lo, Ikai; Shih, Cheng-Hung; Pang, Wen-Yuan; Tsai, Cheng-Da; Lin, Yu-Chiao

    2013-03-01

    High-efficiency red, green and blue light-emitting diodes (LEDs) can be used in the construction of full color display. We have grown green and blue light InGaN/GaN multiquantum-well (MQW) thin film on sapphire substrate with GaN buffer by using plasma-assisted molecular beam epitaxy. The optical properties of the samples were analyzed by photoluminescence measurement in room temperature. Under constant nitrogen flux condition, we obtained the blue and green emitting bands from different samples by modified the Indium and Gallium flux ratio in MQW. In high nitrogen flux condition, the wavelength shifts to 560nm, which provides an effective way to reach high Indium incorporation LED. In order to improve the quality, we can control the growth temperature and InGaN/GaN thickness. There are more than five order satellite peaks in Double Crystal X-ray Diffraction data. Smooth surface morphology has been verified in our samples by scanning electron microscope. This project is supported by National science council of Taiwan (NSC 101-2112-M-110-006-MY3).

  14. LIGHT / DARK PREFERENCE IN Danio rerio: EFFECTS OF LIGHT EXPOSURE DURATION AND DAY PERIOD

    Directory of Open Access Journals (Sweden)

    Claudio Alberto Gellis de Mattos Dias

    2014-10-01

    Full Text Available The animals have anatomical and physiological structures influenced by luminosity. In fish, the pineal gland cells contain photoreceptors and the suprachiasmatic nucleus seems to be involved in biological rhythm just like in other vertebrates. This work aims to describe the role of luminosity and day periods in Danio rerio's Light/Dark preference. For this purpose 160 naive adult undetermined sex Zebrafish were divided into 5 groups of 32 subjects and kept in isolated aquaria with light control. Afterwards, each fish was tested in the Light/Dark aquaria, with water column of 5 centimeters. There was an habituation period of 5 minutes (300 seconds followed by removal of the sliding doors, allowing the subjects to explore the apparatus for 15 minutes (900 seconds. Tests were performed in different day periods, as follows: Morning (06:00 – 12:00 h; Afternoon (12:00 – 18:00 h; Night (18:00 – 24:00 h; Late Night (24:00 – 06:00 h. Our results show that the time of permanence is sensitive to day period. The number of crossings and latency were not influenced by the period of the day. Further studies regarding biological basis of Light/Dark Preference should be carried out in order to understand the role of circadian function in Danio rerio's behavior. Keywords: Danio rerio, zebrafish, behavior, light-dark preference, anxiety. DOI: http://dx.doi.org/10.18561/2179-5746/biotaamazonia.v4n3p106-111

  15. Visible light induced degradation of methylene blue using CeO2/V2O5 and CeO2/CuO catalysts

    International Nuclear Information System (INIS)

    In the present study, the nanocatalysts CeO2, V2O5, CuO, CeO2/V2O5 and CeO2/CuO were synthesized by thermal decomposition method. This method is simple, fast and cost effective compared with other preparation methods. The synthesized catalysts were characterized by different techniques. The XRD and XPS results confirmed the structure and the oxidization states of the nanocomposite materials. DRS results suggested that the prepared CeO2/V2O5 and CeO2/CuO nanocomposites can generate more electrons and holes under visible light irradiation. The photocatalytic activities of prepared catalysts were evaluated using the degradation of aqueous methylene blue solution as a model compound under visible light irradiation. In addition, the nanocomposite (CeO2/V2O5 and CeO2/CuO) materials were employed to degrade the textile effluent under visible light condition. - Highlights: • The catalysts were synthesized via a facile thermal decomposition method which was simple, fast and feasible method. • Degradation of methylene blue and real effluent were carried out under visible light. • The photocatalytic activity of nanocomposite materials is higher than that of single phase material

  16. Photo-catalytic H2 evolution over a series of Keggin-structure heteropoly blue sensitized Pt/TiO2 under visible light irradiation

    International Nuclear Information System (INIS)

    We report the visible light-induced hydrogen generation over a series of Keggin-structure heteropoly blue (HPB) anions (PW12O403-, phosphotungstic blue (PTB), GeW12O404- (GTB), SiW12O404- (STB), BW12O405- (BTB)) sensitized Pt/TiO2 photo-catalysts. The sensitization of TiO2 by HPB was certified using photo-electrochemical measurements and UV-vis absorption spectra. PTB showed the most pronounced sensitization effect for TiO2 in those HPB anions and Pt/TiO2-PTB showed the highest hydrogen generation activity. The sensitization of TiO2 was significantly dependent on the reduction potential of HPA, which was determined by the kind of central atom in HPA.

  17. Carrier recombination spatial transfer by reduced potential barrier causes blue/red switchable luminescence in C8 carbon quantum dots/organic hybrid light-emitting devices

    Science.gov (United States)

    Chen, Xifang; Yan, Ruolin; Zhang, Wenxia; Fan, Jiyang

    2016-04-01

    The underlying mechanism behind the blue/red color-switchable luminescence in the C8 carbon quantum dots (CQDs)/organic hybrid light-emitting devices (LEDs) is investigated. The study shows that the increasing bias alters the energy-level spatial distribution and reduces the carrier potential barrier at the CQDs/organic layer interface, resulting in transition of the carrier transport mechanism from quantum tunneling to direct injection. This causes spatial shift of carrier recombination from the organic layer to the CQDs layer with resultant transition of electroluminescence from blue to red. By contrast, the pure CQDs-based LED exhibits green-red electroluminescence stemming from recombination of injected carriers in the CQDs.

  18. Blue Light Signaling Inactivates the Mating Type Genes-Mediated Repression of Asexual Spore Production in the Higher Basidiomycete Coprinopsis cinerea

    Directory of Open Access Journals (Sweden)

    Prayook Srivilai

    2009-01-01

    Full Text Available Monokaryotic mycelia of several wild-type strains of the homobasidiomycete Coprinopsis cinerea form abundant numbers of oidia both in the light and dark due to the regulation of oidia production by the A and B mating type genes. Nevertheless, little is known about whether and how the mating type loci and light signal regulate the oidiation in C. cinerea. Herein, the experimental results demonstrated that the self-compatible homokaryon AmutBmut strain, the mycelia whose nuclei carry mutations in both the A and B loci, can produce only a few oidia in the dark, whereas the formation of numerous numbers of oidia is induced by the light. The semi-compatible homokaryon AmutB, but not ABmut, has the production and behavior of oidia formation similar to those of AmutBmut. These findings indicated that in AmutBmut strain the mutation at the A locus results in repression of oidiation in the dark and the blue light alleviates this effect, whereas the mutated B genes function has no effects. Since, the oidia production relies on both A and light signal, it is possible that A locus might be linked to the blue light receptor genes. The present results demonstrated for the first time that the secondary hyphal knot formation(skn1, fruiting body maturation (mat and basidiospore formation (bad genes which are essential in the C. cinerea fruiting pathway are not involved in the regulation of asexual sporulation. In addition, the positive light effect on oidiation could also occur in C. cinerea dikaryons.

  19. Trypan Blue Staining to Determine Vaginal Exposure in Two Types of Plastic Vaginal Applicators Containing Two Different Microbicide Formulations

    OpenAIRE

    Hemmerling, A.; Harrison, WG; Brown, JM; Moscicki, AB; Oziemkowska, M; Bukusi, EA; Cohen, CR

    2012-01-01

    Dye staining of applicators has been shown to be a reliable and objective method to test vaginal insertion in clinical microbicide trials, but different plastics, dyes and product formulations may impact the accuracy of this method. Reportedly used applicators returned from three clinical trials were stained with 1% Trypan Blue. In a phase 1 study (VivaGel®), using gel-filled HTI polypropylene applicators, 1271 (97%) of applicators stained positive. In two phase 1 and 2a studies (LACTIN-V) us...

  20. Hydroxyl radicals cause fluctuation in intracellular ferrous ion levels upon light exposure during photoreceptor cell death.

    Science.gov (United States)

    Imamura, Tomoyo; Hirayama, Tasuku; Tsuruma, Kazuhiro; Shimazawa, Masamitsu; Nagasawa, Hideko; Hara, Hideaki

    2014-12-01

    Iron accumulation is a potential pathogenic event often seen in age-related macular degeneration (AMD) patients. In this study, we focused on the relationship between AMD pathology and concentrations of ferrous ion, which is a highly reactive oxygen generator in biological systems. Murine cone-cells-derived 661 W cells were exposed to white fluorescence light at 2500 lx for 1, 3, 6, or 12 h. Levels of ferrous ions, reactive oxygen species (ROS), and hydroxyl radicals were detected by RhoNox-1, a novel fluorescent probe for the selective detection of ferrous ion, 5-(and-6)-chloromethyl-2',7'-dichlorodihydrofluorescein diacetate, acetyl ester (CM-H2DCFDA), and 3'-p-(aminophenyl) fluorescein, respectively. Reduced glutathione, total iron levels and photoreceptor cell death were also measured. Two genes related to iron metabolism, transferrin receptor 1 (TfR1) and H ferritin (HFt), were quantified by RT-PCR. The effects of ferrous ion on cell death and hydroxyl radical production were determined by treatment with a ferrous ion chelating agent, 2,2'-bipyridyl. We found that the ferrous ion level decreased with light exposure in the short time frame, whereas it was upregulated during a 6-h light exposure. Total iron, ROS, cell death rate, and expression of TfR and HFt genes were significantly increased in a time-dependent manner in 661 W cells exposed to light. Chelation with 2,2'-bipyridyl reduced the level of hydroxyl radicals and protected against light-induced cell death. These results suggest that light exposure decreases ferrous ion levels and enhances iron uptake in photoreceptor cells. Ferrous ion may be involved in light-induced photoreceptor cell death through production of hydroxyl radicals. PMID:25447561

  1. Light

    CERN Document Server

    Robertson, William C

    2003-01-01

    Why is left right and right left in the mirror? Baffled by the basics of reflection and refraction? Wondering just how the eye works? If you have trouble teaching concepts about light that you don t fully grasp yourself, get help from a book that s both scientifically accurate and entertaining with Light. By combining clear explanations, clever drawings, and activities that use easy-to-find materials, this book covers what science teachers and parents need to know to teach about light with confidence. It uses ray, wave, and particle models of light to explain the basics of reflection and refraction, optical instruments, polarization of light, and interference and diffraction. There s also an entire chapter on how the eye works. Each chapter ends with a Summary and Applications section that reinforces concepts with everyday examples. Whether you need a deeper understanding of how light bends or a good explanation of why the sky is blue, you ll find Light more illuminating and accessible than a college textbook...

  2. Aging characteristics of blue InGaN micro-light emitting diodes at an extremely high current density of 3.5 kA cm-2

    Science.gov (United States)

    Tian, Pengfei; Althumali, Ahmad; Gu, Erdan; Watson, Ian M.; Dawson, Martin D.; Liu, Ran

    2016-04-01

    The aging characteristics of blue InGaN micro-light emitting diodes (micro-LEDs) with different sizes have been studied at an extremely high current density 3.5 kA cm-2 for emerging micro-LED applications including visible light communication (VLC), micro-LED pumped organic lasers and optogenetics. The light output power of micro-LEDs first increases and then decreases due to the competition of Mg activation in p-GaN layer and defect generation in the active region. The smaller micro-LEDs show less light output power degradation compared with larger micro-LEDs, which is attributed to the lower junction temperature of smaller micro-LEDs. It is found that the high current density without additional junction temperature cannot induce significant micro-LED degradation at room temperature but the combination of the high current density and high junction temperature leads to strong degradation. Furthermore, the cluster LEDs, composed of a micro-LED array, have been developed with both high light output power and less light output degradation for micro-LED applications in solid state lighting and VLC.

  3. Effect of red and blue light emitting diodes "CRB-LED" on in vitro organogenesis of date palm (Phoenix dactylifera L.) cv. Alshakr.

    Science.gov (United States)

    Al-Mayahi, Ahmed Madi Waheed

    2016-10-01

    The objective of the present study is to determine the effect of light source on enhancement of shoot multiplication, phytochemicals, as well as, antioxidant enzyme activities of in vitro cultures of date palm cv. Alshakr. In vitro-grown buds were cultured on Murashige and Skoog (MS) medium and incubated under a conventional white fluorescent light (control), and combinations of red + blue light emitting diode (18:2) (CRB-LED). Results revealed that the treatment of CRB-LED showed a significant increase in the number of shoots compared with the white florescent light. Total soluble carbohydrate "TSCH" (7.10 mg g(-1) DW.), starch (1.63 mg g(-1) DW.) and free amino acids (2.90 mg g(-1) DW.) were significantly higher in CRB-LED (p fluorescent light treatment (19.74 U ml(-1)) as control treatment. Potassium, magnesium and sodium contents in (3.62, 13.99 and 2.76 mg g(-1) DW.) were increased in in vitro shoots under CRB-LED treatment in comparison with fluorescent light (p light during the course of date palm tissue cultures. PMID:27562594

  4. Aging characteristics of blue InGaN micro-light emitting diodes at an extremely high current density of 3.5 kA cm−2

    International Nuclear Information System (INIS)

    The aging characteristics of blue InGaN micro-light emitting diodes (micro-LEDs) with different sizes have been studied at an extremely high current density 3.5 kA cm−2 for emerging micro-LED applications including visible light communication (VLC), micro-LED pumped organic lasers and optogenetics. The light output power of micro-LEDs first increases and then decreases due to the competition of Mg activation in p-GaN layer and defect generation in the active region. The smaller micro-LEDs show less light output power degradation compared with larger micro-LEDs, which is attributed to the lower junction temperature of smaller micro-LEDs. It is found that the high current density without additional junction temperature cannot induce significant micro-LED degradation at room temperature but the combination of the high current density and high junction temperature leads to strong degradation. Furthermore, the cluster LEDs, composed of a micro-LED array, have been developed with both high light output power and less light output degradation for micro-LED applications in solid state lighting and VLC. (paper)

  5. Light extraction efficiency enhancement of GaN-based blue LEDs based on ITO/ InxO ohmic contacts with microstructure formed by annealing in oxygen.

    Science.gov (United States)

    Luo, Yi; Bai, Yiming; Han, Yanjun; Li, Hongtao; Wang, Lai; Wang, Jian; Sun, Changzheng; Hao, Zhibiao; Xiong, Bing

    2016-05-16

    Indium tin oxide (ITO)/ indium oxide (InxO) double layer structure was adopted as the transparent conduction and light scattering function layer to improve the light extraction efficiency of the GaN-based blue LEDs. The double layer structure was first deposited in one run by electron beam evaporation using ITO and Indium as the source respectively, and then annealed in an oxygen environment. This method can fabricate transparent electrode with microstructure and low specific contact resistivity one time free from lithography and etching, which makes the fabrication process simple and at a ower cost. For the 220 nm ITO/ 170 nm InxO double layer sample annealed at 600°C for 15 min in oxygen, measurement results show that its root mean square of roughness of the surface microstructure can be as high as 85.2 nm which introduces the strongest light scattering. Its light transmittance at 450 nm can maintain 92.4%. At the same time, it can realize lower specific contact resistivity with p-InGaN. Compared with the GaN-based blue LEDs with only 220 nm ITO electrode, the light output power of the LEDs with 220 nm ITO/ 170 nm InxO double layer structure can be increased about 58.8%, and working voltage at 20 mA injection current is decreased about 0.23 V due to the enhanced current spreading capability. The light output power improvement is also theoretically convinced by finite difference time domain simulations. PMID:27409953

  6. Effects of exposure to intermittent versus continuous red light on human circadian rhythms, melatonin suppression, and pupillary constriction.

    Science.gov (United States)

    Ho Mien, Ivan; Chua, Eric Chern-Pin; Lau, Pauline; Tan, Luuan-Chin; Lee, Ivan Tian-Guang; Yeo, Sing-Chen; Tan, Sara Shuhui; Gooley, Joshua J

    2014-01-01

    Exposure to light is a major determinant of sleep timing and hormonal rhythms. The role of retinal cones in regulating circadian physiology remains unclear, however, as most studies have used light exposures that also activate the photopigment melanopsin. Here, we tested the hypothesis that exposure to alternating red light and darkness can enhance circadian resetting responses in humans by repeatedly activating cone photoreceptors. In a between-subjects study, healthy volunteers (n = 24, 21-28 yr) lived individually in a laboratory for 6 consecutive days. Circadian rhythms of melatonin, cortisol, body temperature, and heart rate were assessed before and after exposure to 6 h of continuous red light (631 nm, 13 log photons cm(-2) s(-1)), intermittent red light (1 min on/off), or bright white light (2,500 lux) near the onset of nocturnal melatonin secretion (n = 8 in each group). Melatonin suppression and pupillary constriction were also assessed during light exposure. We found that circadian resetting responses were similar for exposure to continuous versus intermittent red light (P = 0.69), with an average phase delay shift of almost an hour. Surprisingly, 2 subjects who were exposed to red light exhibited circadian responses similar in magnitude to those who were exposed to bright white light. Red light also elicited prolonged pupillary constriction, but did not suppress melatonin levels. These findings suggest that, for red light stimuli outside the range of sensitivity for melanopsin, cone photoreceptors can mediate circadian phase resetting of physiologic rhythms in some individuals. Our results also show that sensitivity thresholds differ across non-visual light responses, suggesting that cones may contribute differentially to circadian resetting, melatonin suppression, and the pupillary light reflex during exposure to continuous light. PMID:24797245

  7. Understanding Xeroderma Pigmentosum Complementation Groups Using Gene Expression Profiling after UV-Light Exposure

    Directory of Open Access Journals (Sweden)

    Nikola A. Bowden

    2015-07-01

    Full Text Available Children with the recessive genetic disorder Xeroderma Pigmentosum (XP have extreme sensitivity to UV-light, a 10,000-fold increase in skin cancers from age 2 and rarely live beyond 30 years. There are seven genetic subgroups of XP, which are all resultant of pathogenic mutations in genes in the nucleotide excision repair (NER pathway and a XP variant resultant of a mutation in translesion synthesis, POLH. The clinical symptoms and severity of the disease is varied across the subgroups, which does not correlate with the functional position of the affected protein in the NER pathway. The aim of this study was to further understand the biology of XP subgroups, particularly those that manifest with neurological symptoms. Whole genome gene expression profiling of fibroblasts from each XP complementation group was assessed before and after UV-light exposure. The biological pathways with altered gene expression after UV-light exposure were distinct for each subtype and contained oncogenic related functions such as perturbation of cell cycle, apoptosis, proliferation and differentiation. Patients from the subgroups XP-B and XP-F were the only subgroups to have transcripts associated with neuronal activity altered after UV-light exposure. This study will assist in furthering our understanding of the different subtypes of XP which will lead to better diagnosis, treatment and management of the disease.

  8. CeO2-ZnO hexagonal nanodisks: Efficient material for the degradation of direct blue 15 dye and its simulated dye bath effluent under solar light

    International Nuclear Information System (INIS)

    Highlights: • Synthesis of CeO2-ZnO hexagonal nanodisks. • Excellent morphological, crystalline and photoluminescent properties. • Solar light responsive photocatalyst for degradation of direct blue 15 dye and its simulated dye bath effluent. - Abstract: Well-crystalline CeO2-ZnO hexagonal nanodisks were synthesized by simple and facile chemical reaction process at low-temperature and characterized in detail by using several techniques such as powder X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infrared (FTIR) spectroscopy, thermal gravimetric analysis (TGA), UV–vis diffuse reflectance spectroscopy (DRS), photoluminescence (PL) emission spectroscopy and X-ray photoelectron spectroscopy (XPS). The detailed characterizations results revealed that the prepared samples are well-crystalline with good optical and structural properties and possessing hexagonal morphologies. Further, the prepared material was used as efficient photocatalyst for the photocatalytic degradation of highly hazardous direct blue (DB)-15 dye under solar light irradiation. The CeO2-ZnO hexagonal nanodisks exhibited superior photocatalytic performance towards the degradation of DB 15 dye and its simulated dye bath effluent under solar light. The enhanced photocatalytic activity of CeO2-ZnO hexagonal nanodisks could be attributed to the suppression of photo-induced e−/h+ pair recombination. Moreover, various scavengers have been used to study the role of reactive species in the photo-degradation process

  9. Feeling blue? Blue phosphors for OLEDs

    Directory of Open Access Journals (Sweden)

    Hungshin Fu

    2011-10-01

    Full Text Available Research on organic light emitting diodes (OLEDs has been revitalized, partly due to the debut of the OLED TV by SONY in 2008. While there is still plenty of room for improvement in efficiency, cost-effectiveness and longevity, it is timely to report on the advances of light emitting materials, the core of OLEDs, and their future perspectives. The focus of this account is primarily to chronicle the blue phosphors developed in our laboratory. Special attention is paid to the design strategy, synthetic novelty, and their OLED performance. The report also underscores the importance of the interplay between chemistry and photophysics en route to true-blue phosphors.

  10. Mechanisms of Loss in Internal Quantum Efficiency in III-Nitride-based Blue-and Green-Light Emitting Diodes

    Science.gov (United States)

    Huang, Li

    The overarching goals of the research conducted for this dissertation have been to understand the scientific reasons for the losses in the internal quantum efficiency (IQE) in Group III-nitride-based blue and especially green light-emitting diodes (LEDs) containing a multi-quantum well (MQW) active region and to simultaneously develop LED epitaxial structures to ameliorate these losses. The p-type AlGaN EBL was determined to be both mandatory and effective in the prevention of electron overflow from the MQW region into the p-type cladding layer and the resultant lowering of the IQE. The overflow phenomenon was partially due to the low concentration (˜ 5 x 1017 cm-3) and mobility (˜ 10 cm2/(V•s)) of the holes injected into the active region. Electroluminescence (EL) studies of LEDs without an EBL revealed a dominant emission from donor-acceptor pair recombination in the p-type GaN layer. The incorporation of a 90 nm compositionally graded In0-0.1 Ga1-0.9N buffer layer between each MQW and n-GaN cladding layer grown on an Al/SiC substrate resulted in an increase in the luminescence intensity and a blue-shift in the emission wavelength, as observed in photoluminescence (PL) spectra. The graded InGaN buffer layer reduced the stress and thus the piezoelectric field across the MQW; this improved the electron/hole overlap that, in turn, resulted in an enhanced radiative recombination rate and an increase in efficiency. A direct correlation was observed between an increase in the IQE measured in temperature-dependent PL (TDPL) and an increase in the roughness of all the upper InGaN QW/GaN barrier interfaces, as determined using cross-sectional transmission electron microscopy of the MQW. These results agreed in general with the average surface roughness values of the pit-free region on the top GaN barrier determined via atomic force microscopy and the average roughness values of all the interfaces in the MQW calculated from the FWHM of the emission peak in the PL

  11. Light-Emitting-Diodes based on ordered InGaN nanocolumns emitting in the blue, green and yellow spectral range.

    OpenAIRE

    Bengoechea Encabo, Ana; Albert, Steven; López-Romero Moraleda, David; Lefebvre, P.; Barbagini, Francesca; Torres Pardo, Almudena; González Calbet, José María; Sánchez García, Miguel Angel; Calleja Pardo, Enrique

    2014-01-01

    The growth of ordered arrays of InGaN/GaN nanocolumnar light emitting diodes by molecular beam epitaxy, emitting in the blue (441 nm), green (502 nm), and yellow (568 nm) spectral range is reported. The device active region, consisting of a nanocolumnar InGaN section of nominally constant composition and 250 to 500 nm length, is free of extended defects, which is in strong contrast to InGaN layers (planar) of similar composition and thickness. The devices are driven under pulsed operation up ...

  12. 2,4-Dicyano-3-diethylamino-9,9-diethylfluorene Based Blue Light-emitting Star-shaped Compounds: Synthesis and Properties

    Institute of Scientific and Technical Information of China (English)

    CHEN,Xiaohang; CHEN,Xiaopeng; ZHAO,Zujin; L(U),Ping; WANG,Yanguang

    2009-01-01

    Two new star-shaped molecules 1 and 2 containing a triphenylamine/benzene moiety as the central core and three 2,4-dicyano-3-diethylamino-9,9-diethylfluorene moieties as the peripheral functional groups were synthesized and characterized. Charge transfer properties for these compounds were observed in photophysical experiments due to their D-A molecular structure. Compound 1 presented dual fluorescence in high polar solvents. Moreover, these compounds exhibited moderate fluorescence and high thermal stabilities, indicating their potential application to blue light emitting materials.

  13. Strong violet-blue light photoluminescence emission at room temperature in SrZrO3: Joint experimental and theoretical study

    International Nuclear Information System (INIS)

    Ultrafine ordered and disordered SrZrO3 powders were prepared by the polymeric precursor method. The structural evolution from structural disorder to order was monitored by X-ray diffraction and X-ray absorption near-edge spectroscopy. Complex cluster vacancies [ZrO5.VOZ]and[SrO11.VOZ] (where VOZ=VOX, VO·andVO··) were proposed for disordered powders. The intense violet-blue light photoluminescence emission measured at room temperature in the disordered powders was attributed to complex cluster vacancies. High-level quantum mechanical calculations within the density functional theory framework were used to interpret the experimental results

  14. A New Blue-Emitting Mg2Al4Si5O18:Ce3+ Phosphor for White Light Emitting Diodes.

    Science.gov (United States)

    Chen, Jian; Ma, Hongyun; Liu, Yangai

    2016-04-01

    A series of blue-emitting Mg2Al4Si5O18:Ce3+ phosphors were prepared via the conventional high temperature solid-state reaction method. The phase structure, photoluminescence (PL) properties, PL thermal stability, and fluorescence decay curves of the samples were investigated for the first time. Under excitation at 365 nm, the phosphor exhibited a broad band blue emission with peak at 440 nm, which was ascribed to the 4f --> 5d transition of Ce3+, and the color coordinate was (0.1602, 0.0849). When the temperature increased to 150 °C, the luminescence intensity of the Mg2Al4Si5O18:0.06Ce3+ phosphor was 55.73% of the initial value at room temperature. The activation energy ΔE was calculated to be 0.25 eV, which proved the good thermal stability of the sample. The energy transfer critical distance between Ce3+ ions in Mg2Al4Si5O18 host were also calculated. The above results indicate that the Mg2Al4Si5O18:Ce3+ is a promising candidate as a blue-emitting near ultraviolet convertible phosphor for application in white light emitting diodes (WLEDs). PMID:27451657

  15. Organic light-emitting diodes based on 9-(2-naphthyl)anthracene derivatives with a triphenylsilane unit as the deep-blue emitting layer

    Energy Technology Data Exchange (ETDEWEB)

    Song, Ji Young; Lee, Seul Bee [Department of Chemistry, Sungkyunkwan University, Suwon 440-746 (Korea, Republic of); Lee, Seok Jae [Department of Information Display, Hongik University, Seoul 121-791 (Korea, Republic of); Kim, Young Kwan, E-mail: kimyk@wow.hongik.ac.kr [Department of Information Display, Hongik University, Seoul 121-791 (Korea, Republic of); Yoon, Seung Soo, E-mail: ssyoon@skku.edu [Department of Chemistry, Sungkyunkwan University, Suwon 440-746 (Korea, Republic of)

    2015-02-27

    A series of 9-(2-naphthyl)anthracene derivatives with a triphenylsilane unit, which prevented molecular aggregation and self-quenching effect, was designed and synthesized. By using various bridges between the 9-(2-naphthyl)anthracene group and the triphenylsilane unit, five deep-blue emitters were obtained and applied as non-doped emitting materials in organic light-emitting diodes (OLEDs) with a device structure of indium–tin-oxide (ITO) (180 nm)/4,4-bis(N-(1-naphthyl)-N-phenylamino)biphenyl (NPB) (50 nm)/emitting materials (30 nm)/4,7-diphenyl-1,10-phenanthroline (Bphen) (30 nm)/lithium quinolate (Liq) (2 nm)/Aluminium (100 nm). All devices showed blue emissions and their electroluminescence efficiencies are sensitive to the structural changes of the emitting materials. In particular, a device using 9-(2-naphthalenyl)-10-[6-(triphenylsilyl)-2-naphthalenyl]-anthracene (4) exhibited high luminous, power and quantum efficiencies of 2.28 cd/A, 1.42 lm/W and 2.40% at 20 mA/cm{sup 2}, respectively, and this device showed the deep blue emission with the CIE coordinates of (0.16, 0.10) at 6.0 V. - Highlights: • We synthesized 9-(2-naphthyl)anthracene derivatives with a triphenylsilane unit. • We study the conjugation-length effect on the electroluminescence properties. • The bulky triphenylsilane-anthracene derivatives show resistance to self-aggregation.

  16. Organic light-emitting diodes based on 9-(2-naphthyl)anthracene derivatives with a triphenylsilane unit as the deep-blue emitting layer

    International Nuclear Information System (INIS)

    A series of 9-(2-naphthyl)anthracene derivatives with a triphenylsilane unit, which prevented molecular aggregation and self-quenching effect, was designed and synthesized. By using various bridges between the 9-(2-naphthyl)anthracene group and the triphenylsilane unit, five deep-blue emitters were obtained and applied as non-doped emitting materials in organic light-emitting diodes (OLEDs) with a device structure of indium–tin-oxide (ITO) (180 nm)/4,4-bis(N-(1-naphthyl)-N-phenylamino)biphenyl (NPB) (50 nm)/emitting materials (30 nm)/4,7-diphenyl-1,10-phenanthroline (Bphen) (30 nm)/lithium quinolate (Liq) (2 nm)/Aluminium (100 nm). All devices showed blue emissions and their electroluminescence efficiencies are sensitive to the structural changes of the emitting materials. In particular, a device using 9-(2-naphthalenyl)-10-[6-(triphenylsilyl)-2-naphthalenyl]-anthracene (4) exhibited high luminous, power and quantum efficiencies of 2.28 cd/A, 1.42 lm/W and 2.40% at 20 mA/cm2, respectively, and this device showed the deep blue emission with the CIE coordinates of (0.16, 0.10) at 6.0 V. - Highlights: • We synthesized 9-(2-naphthyl)anthracene derivatives with a triphenylsilane unit. • We study the conjugation-length effect on the electroluminescence properties. • The bulky triphenylsilane-anthracene derivatives show resistance to self-aggregation

  17. Effects of blue light irradiation on dental enamel remineralization in vitro; Avaliacao dos efeitos promovidos pela radiacao azul na remineralizacao do esmalte dentario in vitro

    Energy Technology Data Exchange (ETDEWEB)

    Kato, Ilka Tiemy

    2009-07-01

    This study aimed to investigate the effects of blue radiation on dental enamel remineralization. In addition, a methodology of analysis was developed to evaluate alterations of enamel mineral content by optical coherence tomography. Artificial lesions were formed in bovine dental enamel slabs by immersing the samples in under saturated acetate buffer (2 mL/mm{sup 2} e 6.25 mL/mm{sup 2}). The lesions were irradiated with blue LED (l=455{+-}20nm), with radiant power of 110 mW, irradiance of 1.4 W/cm{sup 2}, radiant exposure of 13.8 J/{sup c}m2 and exposure time of 10 s. Remineralization was induced by pH-cycling model during 8 days. Cross-sectional hardness and optical coherence tomography (OCT) were used to assess mineral changes after remineralization. Hardness data showed that non-irradiated enamel lesions presented higher mineral content than irradiated ones and this difference was more evident in lesions formed in higher solution volume. The analysis of OCT signal also demonstrated that the mineral content of non-irradiated group was higher than in irradiated one; however, no significant difference was observed. Furthermore, significant differences in OCT sign were detected between sound and demineralized enamel. Based on the results obtained in the present study it can be concluded that blue radiation caused an inhibition of enamel remineralization. The methodology adopted for OCT analysis allowed the quantification of enamel mineral loss; however, the remineralization process could not be evaluated by this technique. (author)

  18. Cadmium bioaccumulation and retention kinetics in the Chilean blue mussel Mytilus chilensis: Seawater and food exposure pathways

    Energy Technology Data Exchange (ETDEWEB)

    Herve-Fernandez, Pedro [Instituto de Geociencias, Universidad Austral de Chile, Castilla 567, Valdivia (Chile); Houlbreque, Fanny, E-mail: F.Houlbreque@iaea.org [International Atomic Energy Agency - Marine Environment Laboratories, 4 Quai Antoine 1er, 98000 Monaco (Monaco); Boisson, Florence [International Atomic Energy Agency - Marine Environment Laboratories, 4 Quai Antoine 1er, 98000 Monaco (Monaco); Mulsow, Sandor [Instituto de Geociencias, Universidad Austral de Chile, Castilla 567, Valdivia (Chile); Teyssie, Jean-Louis; Oberhaensli, Francois; Azemard, Sabine; Jeffree, Ross [International Atomic Energy Agency - Marine Environment Laboratories, 4 Quai Antoine 1er, 98000 Monaco (Monaco)

    2010-09-15

    The Chilean blue mussel (Mytilus chilensis, Hupe 1854) represents the most important bivalve exploited along the Chilean coast and is a major food source for the Chilean population. Unfortunately, local fish and shellfish farming face severe problems as a result of bioaccumulation of toxic trace metals into shellfishes. Blue mussels collected along the Chilean coasts contain levels of Cd above the regulatory limits for human consumption. In this study, we examined the bioaccumulation, depuration and organ distribution of Cd in the M. chilensis, from {sup 109}Cd-labelled bulk seawater and from feeding with {sup 109}Cd-labelled algae. The uptake of {sup 109}Cd via seawater displayed a simple exponential kinetic model suggesting that cadmium activity tends to reach an equilibrium value of 1.838 {+-} 0.175 ng g{sup -1} (mean {+-} asymptotic standard error, p < 0.001) after 78 {+-} 9 days. The depuration rate for {sup 109}Cd accumulated via seawater was slow, with only 21% of the total {sup 109}Cd accumulated in the whole mussel being eliminated after 52 days. Total elimination of Cd in mussels was adequately described by a double component kinetic model, in which the biological half-life for the long-lived component represents more than 6 months. In contrast, depuration after radiolabelled food uptake was fast, reaching only 20% of retention in 10 days. This knowledge of the long half-life of cadmium accumulated via seawater as well as the non-negligible level of cadmium accumulated into the shells is relevant to the management of Cd levels in this species and the refinement of detoxification processes in order to comply with authorized Cd levels.

  19. Cadmium bioaccumulation and retention kinetics in the Chilean blue mussel Mytilus chilensis: Seawater and food exposure pathways

    International Nuclear Information System (INIS)

    The Chilean blue mussel (Mytilus chilensis, Hupe 1854) represents the most important bivalve exploited along the Chilean coast and is a major food source for the Chilean population. Unfortunately, local fish and shellfish farming face severe problems as a result of bioaccumulation of toxic trace metals into shellfishes. Blue mussels collected along the Chilean coasts contain levels of Cd above the regulatory limits for human consumption. In this study, we examined the bioaccumulation, depuration and organ distribution of Cd in the M. chilensis, from 109Cd-labelled bulk seawater and from feeding with 109Cd-labelled algae. The uptake of 109Cd via seawater displayed a simple exponential kinetic model suggesting that cadmium activity tends to reach an equilibrium value of 1.838 ± 0.175 ng g-1 (mean ± asymptotic standard error, p 109Cd accumulated via seawater was slow, with only 21% of the total 109Cd accumulated in the whole mussel being eliminated after 52 days. Total elimination of Cd in mussels was adequately described by a double component kinetic model, in which the biological half-life for the long-lived component represents more than 6 months. In contrast, depuration after radiolabelled food uptake was fast, reaching only 20% of retention in 10 days. This knowledge of the long half-life of cadmium accumulated via seawater as well as the non-negligible level of cadmium accumulated into the shells is relevant to the management of Cd levels in this species and the refinement of detoxification processes in order to comply with authorized Cd levels.

  20. Compact High-Power Blue Light from a Diode-Pumped Intracavity-Doubled Nd:YAG Laser

    Institute of Scientific and Technical Information of China (English)

    李德华; 李平雪; 张治国; 张世文

    2002-01-01

    We report an effcient continuous wave (cw) operation of 946 nm and 473nm laser beams generated from a diodepumped composite Nd: YAG rod. A very simple compact linear cavity was employed with cavity length of 35 mm.A composite Nd:YAG laser rod was used to release thermal effects. The maximum cw output of 3.3 W at 946nm was obtained with slope efficiency of 22% at incident pump power of 17.5 W. By intracavity doubling with an LBO crystal, as much as 590mW of single-ended blue output at 473nm was achieved with an optical-optical conversion e fffciency of 3.4%. The total blue output would be 1.06 W with overall conversion efficiency of 6.1% if the lasers emitted in both the directions were taken into account.

  1. Variation of the external quantum efficiency with temperature and current density in red, blue, and deep ultraviolet light-emitting diodes

    Energy Technology Data Exchange (ETDEWEB)

    Park, Jun Hyuk; Lee, Jong Won; Kim, Dong Yeong; Kim, Jong Kyu, E-mail: kimjk@postech.ac.kr [Department of Materials Science and Engineering, Pohang University of Science and Technology (POSTECH), Pohang 790-784 (Korea, Republic of); Cho, Jaehee, E-mail: jcho@chonbuk.ac.kr [School of Semiconductor and Chemical Engineering, Semiconductor Physics Research Center, Chonbuk National University, Jeonju 54896 (Korea, Republic of); Schubert, E. Fred [Department for Electrical, Computer, and Systems Engineering, Rensselaer Polytechnic Institute, Troy, New York 12180 (United States); Kim, Jungsub; Lee, Jinsub; Kim, Yong-Il; Park, Youngsoo [LED Business, Samsung Electronics, Yongin 446-920 (Korea, Republic of)

    2016-01-14

    The temperature-dependent external quantum efficiencies (EQEs) were investigated for a 620 nm AlGaInP red light-emitting diodes (LEDs), a 450 nm GaInN blue LED, and a 285 nm AlGaN deep-ultraviolet (DUV) LED. We observed distinct differences in the variation of the EQE with temperature and current density for the three types of LEDs. Whereas the EQE of the AlGaInP red LED increases as temperature decreases below room temperature, the EQEs of GaInN blue and AlGaN DUV LEDs decrease for the same change in temperature in a low-current density regime. The free carrier concentration, as determined from the dopant ionization energy, shows a strong material-system-specific dependence, leading to different degrees of asymmetry in carrier concentration for the three types of LEDs. We attribute the EQE variation of the red, blue, and DUV LEDs to the different degrees of asymmetry in carrier concentration, which can be exacerbated at cryogenic temperatures. As for the EQE variation with temperature in a high-current density regime, the efficiency droop for the AlGaInP red and GaInN blue LEDs becomes more apparent as temperature decreases, due to the deterioration of the asymmetry in carrier concentration. However, the EQE of the AlGaN DUV LED initially decreases, then reaches an EQE minimum point, and then increases again due to the field-ionization of acceptors by the Poole-Frenkel effect. The results elucidate that carrier transport phenomena allow for the understanding of the droop phenomenon across different material systems, temperatures, and current densities.

  2. Variation of the external quantum efficiency with temperature and current density in red, blue, and deep ultraviolet light-emitting diodes

    International Nuclear Information System (INIS)

    The temperature-dependent external quantum efficiencies (EQEs) were investigated for a 620 nm AlGaInP red light-emitting diodes (LEDs), a 450 nm GaInN blue LED, and a 285 nm AlGaN deep-ultraviolet (DUV) LED. We observed distinct differences in the variation of the EQE with temperature and current density for the three types of LEDs. Whereas the EQE of the AlGaInP red LED increases as temperature decreases below room temperature, the EQEs of GaInN blue and AlGaN DUV LEDs decrease for the same change in temperature in a low-current density regime. The free carrier concentration, as determined from the dopant ionization energy, shows a strong material-system-specific dependence, leading to different degrees of asymmetry in carrier concentration for the three types of LEDs. We attribute the EQE variation of the red, blue, and DUV LEDs to the different degrees of asymmetry in carrier concentration, which can be exacerbated at cryogenic temperatures. As for the EQE variation with temperature in a high-current density regime, the efficiency droop for the AlGaInP red and GaInN blue LEDs becomes more apparent as temperature decreases, due to the deterioration of the asymmetry in carrier concentration. However, the EQE of the AlGaN DUV LED initially decreases, then reaches an EQE minimum point, and then increases again due to the field-ionization of acceptors by the Poole-Frenkel effect. The results elucidate that carrier transport phenomena allow for the understanding of the droop phenomenon across different material systems, temperatures, and current densities

  3. Untargeted Metabolomics Reveals Predominant Alterations in Lipid Metabolism Following Light Exposure in Broccoli Sprouts

    OpenAIRE

    Mariateresa Maldini; Fausta Natella; Simona Baima; Giorgio Morelli; Cristina Scaccini; James Langridge; Giuseppe Astarita

    2015-01-01

    The consumption of vegetables belonging to the family Brassicaceae (e.g., broccoli and cauliflower) is linked to a reduced incidence of cancer and cardiovascular diseases. The molecular composition of such plants is strongly affected by growing conditions. Here we developed an unbiased metabolomics approach to investigate the effect of light and dark exposure on the metabolome of broccoli sprouts and we applied such an approach to provide a bird’s-eye view of the overall metabolic response af...

  4. Manifestation of Hyperandrogenism in the Continuous Light Exposure-Induced PCOS Rat Model

    OpenAIRE

    Xuezhi Kang; Lina Jia; Xueyong Shen

    2015-01-01

    Polycystic ovary syndrome (PCOS) is a complex endocrine and metabolic disorder, and its pathogenesis has yet to be completely clarified. A fully convincing animal model has not been established for PCOS. In earlier studies, researchers have shown that the exposure of rats to continuous light can induce PCOS; nevertheless, hyperandrogenism, a key characteristic observed in human PCOS, has not been reported previously. In the present study, we found that (1) body weights decreased in female rat...

  5. Excellent deep-blue emitting materials based on anthracene derivatives for non-doped organic light-emitting diodes

    Science.gov (United States)

    Wang, Zhiqiang; Liu, Wei; Xu, Chen; Ji, Baoming; Zheng, Caijun; Zhang, Xiaohong

    2016-08-01

    Two deep-blue emitting materials 2-tert-butyl-9,10-bis(3,5-diphenylphenyl)anthracene (An-1) and 2-tert-butyl-9,10-bis(3,5-diphenylbiphenyl-4‧-yl)anthracene (An-2) were successfully synthesized by the Pd-catalyzed Suzuki coupling reaction. Both of these compounds have high thermal stabilities and show strong deep-blue emission as solid-state film as well as in n-hexane solution. Two non-doped electroluminescent devices employing An-1 and An-2 as emitting layers were fabricated by vacuum vapor deposition. These devices exhibited highly efficient and stable deep-blue emission with high color purity. The CIE coordinate and maximum EQE of An-1 based device are 4.2% and (0.16, 0.06), respectively. Device based on An-2 achieved a maximum EQE of 4.0% and a CIE coordinate of (0.16, 0.10).

  6. Light emission ranging from blue to red from a series of Iguana/GaN single quantum wells

    International Nuclear Information System (INIS)

    In this paper, we describe the growth and characterization of InGaN single quantum wells with emission peaks in the blue, green, amber and red spectral regions, grown by metal-organic vapour phase epitaxy. Starting from the growth of a blue-emitting (peak ∼430 nm) InGaN quantum well at 860 deg. C the InGaN growth temperature was progressively reduced. The photoluminescence peak wavelength, measured at low temperature, shifts through the green and orange spectral regions and reaches 670 nm for an InGaN growth temperature of 760 deg. C. This corresponds to an energy lower than the currently accepted band-gap of the binary compound, InN. Spectral characteristics of the luminescence peaks will be discussed, including an analysis of the phonon-assisted contribution. Low energy secondary ion mass spectrometry analysis provides information on the indium content and thickness of the 'blue' and 'red' quantum wells. The results are combined to discuss the origin of the 'sub-band-gap' luminescence in terms of the combined influence of InN-GaN segregation and the effect of intense piezoelectric fields. (author)

  7. Light emission ranging from blue to red from a series of Iguana/GaN single quantum wells

    Energy Technology Data Exchange (ETDEWEB)

    Martin, R.W. [Department of Physics, University of Strathclyde, Glasgow (United Kingdom)]. E-mail: r.w.martin@strath.ac.uk; Edwards, P.R.; Pecharroman-Gallego, R.; O' Donnell, K.P. [Department of Physics, University of Strathclyde, Glasgow (United Kingdom); Liu, C.; Deatcher, C.J.; Watson, I.M. [Institute of Photonics, University of Strathclyde, Glasgow (United Kingdom)

    2002-04-07

    In this paper, we describe the growth and characterization of InGaN single quantum wells with emission peaks in the blue, green, amber and red spectral regions, grown by metal-organic vapour phase epitaxy. Starting from the growth of a blue-emitting (peak {approx}430 nm) InGaN quantum well at 860 deg. C the InGaN growth temperature was progressively reduced. The photoluminescence peak wavelength, measured at low temperature, shifts through the green and orange spectral regions and reaches 670 nm for an InGaN growth temperature of 760 deg. C. This corresponds to an energy lower than the currently accepted band-gap of the binary compound, InN. Spectral characteristics of the luminescence peaks will be discussed, including an analysis of the phonon-assisted contribution. Low energy secondary ion mass spectrometry analysis provides information on the indium content and thickness of the 'blue' and 'red' quantum wells. The results are combined to discuss the origin of the 'sub-band-gap' luminescence in terms of the combined influence of InN-GaN segregation and the effect of intense piezoelectric fields. (author)

  8. Short communication: Artificial ultraviolet B light exposure increases vitamin D levels in cow plasma and milk

    DEFF Research Database (Denmark)

    Jakobsen, Jette; Jensen, Søren Krogh; Hymøller, Lone;

    2015-01-01

    group with simulated exposure to 2 h of summer sun daily continued to be monitored for 73 d. We found a significant increase in 25-hydroxyvitamin D-3 (25OHD(3)) levels in plasma as well as vitamin D-3 and 25OHD(3) levels in milk after daily exposure for 24 d in all treatment groups. Extending daily...... exposure to artificial UVB light to 73 d did not lead to an increase of vitamin D-3 or 25OHD(3) level in the milk. In conclusion, the change in production facilities for dairy cows providing cows with no access to pasture and sunlight causes a decrease of vitamin D levels in dairy products. This decrease...

  9. Response of the diatom Phaeodactylum tricornutum to photooxidative stress resulting from high light exposure.

    Directory of Open Access Journals (Sweden)

    Nuno Domingues

    Full Text Available The response of microalgae to photooxidative stress resulting from high light exposure is a well-studied phenomenon. However, direct analyses of photosystem II (PSII D1 protein (the main target of photoinhibition in diatoms are scarce. In this study, the response of the diatom model species Phaeodactylum tricornutum to short-term exposure to high light was examined and the levels of D1 protein determined immunochemically. Low light (LL acclimated cells (40 µmol photons m(-2 s(-1 subjected to high light (HL, 1,250 µmol photons m(-2 s(-1 showed rapid induction of non-photochemical quenching (NPQ and ca. 20-fold increase in diatoxanthin (DT concentration. This resulted from the conversion of diadinoxanthin (DD to DT through the activation of the DD-cycle. D1 protein levels under LL decreased about 30% after 1 h of the addition of lincomycin (LINC, a chloroplast protein synthesis inhibitor, showing significant D1 degradation and repair under low irradiance. Exposure to HL lead to a 3.2-fold increase in D1 degradation rate, whereas average D1 repair rate was 1.3-x higher under HL than LL, leading to decreased levels of D1 protein under HL. There were significant effects of both HL and LINC on P. tricornutum maximum quantum yield of PSII (F(v/F(m, showing a reduction of active PSII reaction centres. Partial recovery of F(v/F(m in the dark demonstrates the photosynthetic resilience of this diatom to changes in the light regime. P. tricornutum showed high allocation of total protein to D1 and an active D1-repair cycle to limit photoinhibition.

  10. Gender features and estrous cycle variations of nocturnal behavior of mice after a single exposure to light at night.

    Science.gov (United States)

    Datta, Siddhartha; Samanta, Diptaman; Sinha, Priyobrata; Chakrabarti, Nilkanta

    2016-10-01

    Light at night alters behavior and cognitive performances in rodents, the variations of which in gender and stages of reproductive cycle in females are elusive. Young mice habituated in light:dark (12:12h) cycle were given a single exposure of light (100lx) at early night for one hour duration followed by experimentations in open field (closed wall with circular big arena), elevated plus maze and square habituated field for memory performance using novel object recognition task. Light effects were compared with results found during without light conditions. Proestrous females appeared to have greater locomotor activity, less anxiety and better memory performance compared to the diestrous females at night without light exposure. The status of locomotor activity, anxiety and memory performance of male mice at night without light exposure appeared to be comparable to females where the stage of estrous cycle is important to characterize the nocturnal behavior of male mice. Light maximally affected proestrous females with decrease in locomotor activity, increase in anxiety and failure of memory performance. Male and diestrous female mice performed memory performance without alteration of locomotor activity and anxiety after exposure to light where males performed better memory performance with greater locomotor activity and more anxiety compared to that of diestrous females. The present study characterizes the mice nocturnal behavior with and without a single exposure to light stimuli with its gender features and estrous cycle variation. In addition, the study indicates an association of memory performance with locomotor activity and anxiety in mice nocturnal behavior. PMID:27241632

  11. Preparation of reduced graphene oxide/meso-TiO2/AuNPs ternary composites and their visible-light-induced photocatalytic degradation n of methylene blue

    Science.gov (United States)

    Yang, Yongfang; Ma, Zheng; Xu, Lidong; Wang, Hefang; Fu, Nian

    2016-04-01

    Reduced graphene oxide/meso-TiO2/AuNPs (RGO/meso-TiO2/AuNPs) ternary composites were prepared via the addition of graphene oxide to the dispersion of meso-TiO2/AuNPs under hydrothermal conditions. The structure and the morphology of the RGO/meso-TiO2/AuNPs materials were characterized using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), and scanning electron microscopy (SEM). The photocatalytic activity of RGO/meso-TiO2/AuNPs was evaluated by degradation of methyl blue (MB) under visible-light illumination. The ternary composites present an extended light absorption range, efficient charge separation properties, high adsorption ability for MB and high photocatalytic degradation activity of MB compared to the meso-TiO2 and meso-TiO2/AuNPs.

  12. Fine-tuning the thicknesses of organic layers to realize high-efficiency and long-lifetime blue organic light-emitting diodes

    International Nuclear Information System (INIS)

    By using p-bis(p − N, N-diphenyl-aminostyryl)benzene doped 2-tert-butyl-9, 10-bis-β-naphthyl)-anthracene as an emitting layer, we fabricate a high-efficiency and long-lifetime blue organic light emitting diode with a maximum external quantum efficiency of 6.19% and a stable lifetime at a high initial current density of 0.0375 A/cm2. We demonstrate that the change in the thicknesses of organic layers affects the operating voltage and luminous efficiency greater than the lifetime. The lifetime being independent of thickness is beneficial in achieving high-quality full-colour display devices and white lighting sources with multi-emitters. (atomic and molecular physics)

  13. Preparation of novel CdS-graphene/TiO2 composites with high photocatalytic activity for methylene blue dye under visible light

    Indian Academy of Sciences (India)

    C Y Park; U Kefayat; N Vikram; T Ghosh; W C Oh; K Y Cho

    2013-10-01

    In this study, CdS combined graphene/TiO2 (CdS-graphene/TiO2) composites were prepared by a sol–gel method to improve on the photocatalytic performance of TiO2. These composites were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX) and transmission electron microscopy (TEM). The photocatalytic activities were examined by the degradation of methylene blue (MB) under visible light irradiation. The photodegradation rate of MB under visible light irradiation reached 90.1% during 150 min. The kinetics of MB degradation were plotted alongside the values calculated from the Langmuir–Hinshelwood equation. 0.1 CGT sample showed the best photocatalytic activity, which was attributed to a cooperative reaction between the increase of photo-absorption effect by graphene and photocatalytic effect by CdS.

  14. Clinical observation of cold light blue light in the treatment of jaundice in premature infants%冷光源蓝光治疗早产儿黄疸的临床观察

    Institute of Scientific and Technical Information of China (English)

    李海燕

    2013-01-01

    目的:探讨LED冷光源蓝光对早产儿黄疸的疗效观察。方法将86例早产儿黄疸住院患儿随机分为治疗组43例,对照组43例。在常规治疗的基础上,治疗组采用LED冷光源蓝光治疗,对照组采用传统蓝光灯治疗,疗程3-5天,于治疗前和治疗后第24小时、48小时经皮测胆红素水平,观察光疗的不良反应。结果与对照组比较,治疗组治疗后24、48小时经皮胆红素水平明显下降,且差异有统计学意义(P<0.05);治疗组在体温、大便、脱水、皮疹、烦躁哭闹等方面发生率明显较对照组低(P<0.05)。结论 LED冷光源蓝光灯治疗能迅速降低胆红素水平,且操作简单,安全,不良反应少,对早产儿损害少。%Objective :Clinical observation on LED cold light blue on jaundice in premature infants.Method:86 cases of jaundice in premature infants hospitalized children were randomly divided into the treatment group of 43 cases, 43 cases in the control group. On the basis of conventional therapy, the treatment group using LED cold light source blue light treatment, the control group used the traditional blue light treatment, treatment 3-5 days, before treatment and after treatment in 24hours, 48 hours, of transcutaneous bilirubin level, to observe the adverse reaction of phototherapy. Result Compared with the control group, treatment of 24, 48,hours after treatment, percutaneous bilirubin level decreased significantly, and the difference was statistical y significant (P < 0.05).The treatment group in the body temperature, stool, dehydration, rash, crying, incidence was significantly lower than that in control group (P < 0.05). Conclusion LED cold light blue light therapy can rapidly reduce the level of bilirubin, and the operation is simple, safety, less adverse reaction, the premature damage less.

  15. Photocurrent response of B{sub 12}As{sub 2} crystals to blue light, and its temperature- dependent electrical characterizations

    Energy Technology Data Exchange (ETDEWEB)

    Gul, R., E-mail: rubi786@yahoo.com [Brookhaven National Laboratory, Upton, NY, 11973 (United States); Alabama A& M University, Normal AL, 35762 (United States); Cui, Y.; Bolotnikov, A. E.; Camarda, G. S.; Hossain, A.; Roy, U. N.; Yang, G.; James, R. B. [Brookhaven National Laboratory, Upton, NY, 11973 (United States); Egarievwe, S. U. [Alabama A& M University, Normal AL, 35762 (United States); Edgar, J. H.; Nwagwu, U. [Kansas State University, Manhattan, KS, 66506 (United States)

    2016-02-15

    With the global shortage of {sup 3}He gas, researchers worldwide are looking for alternative materials for detecting neutrons. Among the candidate materials, semiconductors are attractive because of their light weight and ease in handling. Currently, we are looking into the suitability of boron arsenide (B{sub 12}As{sub 2}) for this specific application. As the first step in evaluating the material qualitatively, the photo-response of B{sub 12}As{sub 2} bulk crystals to light with different wavelengths was examined. The crystals showed photocurrent response to a band of 407- and 470- nm blue light. The maximum measured photoresponsivity and the photocurrent density at 0.7 V for 470 nm blue light at room temperature were 0.25 A ⋅ W{sup −1} and 2.47 mA ⋅ cm{sup −2}, respectively. In addition to photo current measurements, the electrical properties as a function of temperature (range: 50-320 K) were measured. Reliable data were obtained for the low-temperature I-V characteristics, the temperature dependence of dark current and its density, and the resistivity variations with temperature in B{sub 12}As{sub 2} bulk crystals. The experiments showed an exponential dependence on temperature for the dark current, current density, and resistivity; these three electrical parameters, respectively, had a variation of a few nA to μA, 1-100 μA ⋅ cm{sup −2} and 7.6x10{sup 5}-7.7x10{sup 3} Ω ⋅ cm, for temperature increasing from 50 K to 320 K. The results from this study reported the first photoresponse and demonstrated that B{sub 12}As{sub 2} is a potential candidate for thermal-neutron detectors.

  16. Accumulation of copper, chromium, and arsenic in blue mussels (Mytilus edulis) from laboratory and field exposures to wood treated with chromated copper arsenate type C

    Energy Technology Data Exchange (ETDEWEB)

    Adler-Ivanbrook, L.; Breslin, V.T. [State Univ. of New York, Stony Brook, NY (United States)

    1999-02-01

    Laboratory and field experiments were conducted to examine the uptake of Cu, Cr, and As leached from southern yellow pine (SYP) treated with chromated copper arsenate type C (CCA-C), as well as effects on mortality and growth, in blue mussels (Mytilus edulis). Mussels were exposed to CCA-C-treated wood at a preservative retention of 40 kg/m{sup 3} and control (nontreated) SYP in laboratory flow-through sea table and field exposure experiments for 9 months in 1994 and 3 months in 1995. Mussels were sampled at regular intervals to evaluate possible short- and long-term exposure effects., Individual mussels were measured to determine the length, dry weight, and condition index. Mussel tissues were than analyzed for Cu, Cr, and As. Results showed few significant differences in condition index, dry weight, and length between CCA-C-exposed and control mussels. In addition, no statistically significant differences in mortality were found between the mussels exposed to CCA-C-treated and nontreated SYP in the laboratory flow-through sea table and field exposure experiments. Significant differences in Cu, As, and Cr contents in mussel tissues between treatments were few, and generally cannot be attributed to exposure to CCA-C-treated SYP. The lack of Cu, Cr, and As uptake from CCA-C-treated SYP was attributed to the low, although continuous, rate of release of these elements from CCA-C-treated wood and to the experimental design, which allowed continuous flushing, prohibiting the accumulation of these elements in the water surrounding the mussels.

  17. Postpartum Blues

    Medline Plus

    Full Text Available ... Quality Collaboratives Launch Prematurity research centers What is team science? More than 75 years of solving problems ... delivery cause the postpartum blues. How can you manage the baby blues? The American College of Obstetricians ...

  18. Postpartum Blues

    Medline Plus

    Full Text Available ... with this condition are happy most of the time. But compared to how she usually feels, the ... the "blues" usually lessens and goes away over time. What causes the baby blues? Medical experts believe ...

  19. Postpartum Blues

    Medline Plus

    Full Text Available ... Postpartum care > The postpartum blues The postpartum blues E-mail to a friend Please fill in all fields. Please enter a valid e-mail address. Your information: Your recipient's information: Your ...

  20. Postpartum Blues

    Medline Plus

    Full Text Available ... usually lessens and goes away over time. What causes the baby blues? Medical experts believe that changes ... usually lessens and goes away over time. What causes the baby blues? Medical experts believe that changes ...

  1. Postpartum Blues

    Medline Plus

    Full Text Available ... Feels sad Feels confused The postpartum blues peak three to five days after delivery. They usually end ... Feels sad Feels confused The postpartum blues peak three to five days after delivery. They usually end ...

  2. Postpartum Blues

    Medline Plus

    Full Text Available ... postpartum blues Now playing: E-mail to a friend Please fill in all fields. Please enter a ... blues: Talk to your partner or a good friend about how you feel Get plenty of rest ...

  3. Postpartum Blues

    Medline Plus

    Full Text Available ... The postpartum blues The postpartum blues Now playing: E-mail to a friend Please fill in all fields. Please enter a valid e-mail address. Your information: Your recipient's information: Your ...

  4. Postpartum Blues

    Medline Plus

    Full Text Available ... of Obstetricians and Gynecologists recommends that women do these things to help relieve the baby blues: Talk ... of Obstetricians and Gynecologists recommends that women do these things to help relieve the baby blues: Talk ...

  5. Postpartum Blues

    Medline Plus

    Full Text Available ... Medical experts believe that changes in the woman's hormones after delivery cause the postpartum blues. How can ... Medical experts believe that changes in the woman's hormones after delivery cause the postpartum blues. How can ...

  6. Postpartum Blues

    Medline Plus

    Full Text Available ... can you manage the baby blues? The American College of Obstetricians and Gynecologists recommends that women do ... can you manage the baby blues? The American College of Obstetricians and Gynecologists recommends that women do ...

  7. Postpartum Blues

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    Full Text Available ... postpartum blues The postpartum blues E-mail to a friend Please fill in all fields. Please enter ... hear about breakthroughs for babies and families. Ask a question Our health experts can answer questions about ...

  8. Postpartum Blues

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    Full Text Available ... us on Twitter Instagram: behind the scenes Our research Research grants Prematurity research Birth defects research Infant ... postpartum blues are not pleasant, the woman can function normally. The feeling of the "blues" usually lessens ...

  9. Influence of exposure to light on the sensorial quality of minimally processed cauliflower.

    Science.gov (United States)

    Sanz Cervera, Susana; Olarte, Carmen; Echávarri, J Federico; Ayala, Fernando

    2007-01-01

    The impact of lighting on minimally processed cauliflower packaged in 4 different film types (PVC and 3 P-Plus) has been measured and quantified. The effect on the sensorial quality of storage at 4 degrees C in darkness and partial or continuous lighting was evaluated. The gas concentrations in the packages and the weight losses were also determined. Atmosphere composition inside the packages depended on both the permeability of the film used for the packaging and exposure to light. Samples stored with lighting maintained the gaseous exchange between plant tissue and the atmosphere inside the packages for longer periods than in samples kept in darkness. This prompted a greater loss of water vapor as well as the development of atmospheres with low levels of O2 and high levels of CO2 in the samples packed with less permeable films. The most important aspect in sensory evaluation was color. In instrumental color evaluation, coordinates h* and L* were the main means for estimating color evolution. The presence of light accelerated browning in the cut zones. The development of abnormal coloring in these areas marked the end of shelf life for minimally processed cauliflower. Among the sensory attributes studied, color was the most affected by exposure to light. Samples packed in P-Plus 120 film displayed the lowest level of color deterioration in the cut zones. However, under lit conditions, the low permeability of this film caused atmospheres with very low O2 contents and high CO2 contents. These atmospheres produced a loss of texture and the development of off-odors. PMID:17995892

  10. Heavy rare-earth-doped ZBLAN glasses for UV–blue up-conversion and white light generation

    International Nuclear Information System (INIS)

    Noticeable UV–vis up-conversion luminescence of Er3+ and Tm3+ ions sensitised by Yb3+ ions in ZrF4–BaF2–LaF3–AlF3–NaF (ZBLAN) fluoride glasses have been obtained under near-infrared excitation at 980 nm. Red, green and blue simultaneous emissions were observed yielding to a white-balanced overall colour. Moreover significant UV up-conversion emissions observed can contribute to enhance spectral response of semiconductor electrode, such as TiO2 and Fe2O3, for sustainable production of hydrogen via water photolysis by harvesting of long wavelength solar irradiation, emerging as an interesting solely luminescent approach for improving water-splitting. Total infrared to UV–vis up-conversion efficiency has been calculated to be at around 46%. Laboratory tests prove the improvement in the photocatalytic action of a commercial benchmark photocatalyst (TiO2 Degussa P25) in the decomposition of methylene blue in water under sun-like irradiation, by a factor of 16% driven by up-conversion effects due to the inclusion of RE-doped ZBLAN powders into a slurry-type photo-reactor. -- Highlights: • Successful development of heavy rare-earth doped (Yb3+–Tm3+–Er3+) ZBLAN glasses. • Very efficient red, green and blue simultaneous up-conversion emissions yielding to a white-balanced overall colour. • High intense UV up-conversion emissions to enhance spectral response of semiconductor electrode, such as TiO2 and Fe2O3 to boost their photo-catalytic action in water-splitting. • Total infrared to UV–vis up-conversion efficiency calculated to be at around 46%. • Enhancement of about 16% of the photocatalytic activity of commercial TiO2 catalyst

  11. Examining Geospatial Technology Tools to Compensate for Limited Exposures and Integrate Diverse Map and Data Resources in Geological Studies of the Southern Blue Ridge

    Science.gov (United States)

    Collins, N.; Ryan, J. G.

    2010-12-01

    Constraining the tectonic and metamorphic history of rock units in the southern Blue Ridge of western North Carolina is complicated by limited exposures and extensive vegetative cover, as well as burial by human development. Integrating varied data sources for field relations using cyberinformation tools may provide a means around such difficulties. We are examining several different Geographical Information Systems (GIS) tools as a means for effectively integrating available map data, both toward meeting research objectives as well as to facilitate classroom and field instruction. Commercial GIS platforms like ArcGIS and associated software can effectively integrate diverse geoscience information resources within a single platform. The Internet provides free access to databases ranging from geochemical datasets to topographical and structural data. Public domain geochemical databases like EarthChem provide spatially controlled elemental data on rock samples collected by many researchers over extended periods. Once incorporated within the ArcGIS template, this information can then be exported into free geospatial visualization applications such as Goggle Earth, as well as 3D manipulation programs like Fledermaus. Geospatially controlled USGS and NCGS geologic maps and geophysical datasets provide a useful base for examining mafic and ultramafic rock exposures in the Blue Ridge. One can resolve the exposures of specific rock types from these map resources within ArcGIS, as well as fault locations, and magnetics and gravity data. High-resolution DEMs permit data-intensive focusing on areas of interest, and Fledermaus manipulations permit 3D visualization. The output maps and visualizations are of publishable quality, and permit the manipulation of data across a region to infer contact trends and/or chemical or mineralogical, as well as to identify discontinuities that may be geologically relevant. “All-in-one” GIS applications like GeoMapApp have many of these

  12. DNA adduct formation and oxidative stress in colon and liver of Big Blue rats after dietary exposure to diesel particles

    DEFF Research Database (Denmark)

    Dybdahl, Marianne; Risom, Lotte; Møller, Peter;

    2003-01-01

    in liver accompanied by enhanced vitamin C levels. In plasma, we found no significant effects on oxidative damage to proteins and lipids, antioxidant enzymes or vitamin C levels. Our data indicate that gastrointestinal exposure to DEP induces DNA adducts and oxidative stress resulting in DNA strand breaks...... on oxidative DNA damage (8-oxodG) in colon or liver DNA or in the urine. However, the mRNA expression of OGG1, encoding an enzyme involved in repair of 8-oxodG, was increased by DEP in both liver and colon. DNA adduct levels measured by 32P-post-labelling were elevated in colon and liver, and the expression...

  13. Manifestation of Hyperandrogenism in the Continuous Light Exposure-Induced PCOS Rat Model

    Directory of Open Access Journals (Sweden)

    Xuezhi Kang

    2015-01-01

    Full Text Available Polycystic ovary syndrome (PCOS is a complex endocrine and metabolic disorder, and its pathogenesis has yet to be completely clarified. A fully convincing animal model has not been established for PCOS. In earlier studies, researchers have shown that the exposure of rats to continuous light can induce PCOS; nevertheless, hyperandrogenism, a key characteristic observed in human PCOS, has not been reported previously. In the present study, we found that (1 body weights decreased in female rats in a continuous light environment with both ovarian and uterine augmentation; (2 the estrous cycle in rats under continuous light environment was disordered, and polycystic ovary-like changes occurred, accompanied with fur loss and lethargy; and (3 serum testosterone levels in rats in a continuous light environment significantly increased. Our data suggest that continuous light can lead to the occurrence of PCOS in female rats without the need for drugs; this is a reasonable PCOS animal model that is more consistent with the natural disease state in humans; and poor sleep habits or negligence of sleep hygiene may be an important lifestyle factor in pathogenesis of PCOS.

  14. PHH1, a novel gene from Arabidopsis thaliana that encodes a protein similar to plant blue-light photoreceptors and microbial photolyases.

    Science.gov (United States)

    Hoffman, P D; Batschauer, A; Hays, J B

    1996-11-27

    A cDNA from Arabidopsis thaliana similar to microbial photolyase genes, and designated AT-PHH1, was isolated using a photolyase-like cDNA from Sinapsis alba (SA-PHR1) as a probe. Multiple isolations yielded only PHH1 cDNAs, and a few blue-light-receptor CRY1 (HY4) cDNAs (also similar to microbial photolyase genes), suggesting the absence of any other highly similar Arabidopsis genes. The AT-PHH1 and SA-PHR1 cDNA sequences predict 89% identity at the protein level, except for an AT-PHH1 C-terminal extension (111 amino acids), also not seen in microbial photolyases. AT-PHH1 and CRY1 show less similarity (54% p4erein identity), including respective C-terminal extensions that are themselves mostly dissimilar. Analysis of fifteen AT-PHH1 genomic isolates reveals a single gene, with three introns in the coding sequence and one in the 5'-untranslated leader. Full-length AT-PHH1, and both AT-PHH1 and AT-PHH1 delta C-513 (truncated to be approximately the size of microbial photolyase genes) cDNAs, were overexpressed, respectively, in yeast and Escherichia coli mutants hypersensitive to ultraviolet light. The absence of significant effects on resistance suggests either that any putative AT-PHH1 DNA repair activity requires cofactors/chromophores not present in yeast or E. coli, or that AT-PHH1 encodes a blue-light/ultraviolet-A receptor rather than a DNA repair protein. PMID:9003312

  15. Penetration of UV-A, UV-B and blue light through the leaf trichome layers of two xeromorphic plants, olive and oak, measured by optical fibre microprobes

    International Nuclear Information System (INIS)

    Quartz fibre-optic microprobes were used to monitor the light microenvironment beneath trichome layers of the xeromorphic leaves of two Mediterranean evergreen sclerophylls, Olea europaea and Quercus ilex. Young developing leaves of both plants were densely pubescent on both surfaces of the lamina, whereas the mature leaves were pubescent only on the abaxial side. Trichome layers of young as well as of mature leaves of both plants attenuated almost all incident ultraviolet (UV)-B (310 nm) and UV-A (360 nm) radiation and a considerable portion of blue light (430 nm). Abaxial trichome layers of young leaves were more effective in screening out the incident radiation compared to the adaxial ones of the same leaves and also compared to the abaxial layer of the mature leaves. The abaxial epidermis of dehaired mature leaves of O. europaea was ineffective in absorbing most of the incident UV-B and UV-A radiation. UV and visible spectra beneath trichome layers of O. europaea in mature leaves confirmed that the light microenvironment on the epidermis was deprived in the UV-B, UV-A and partly in the blue spectral regions. It is proposed that the occurrence of a dense trichome layer, especially in young leaves, may play a protective role against not only UV-B radiation damage, but also against high visible irradiance. This function is performed irrespective of the differing anatomy of individual hairs of both plants. The protection provided by the trichomes could afford advantages under stress conditions, especially during leaf development. (author)

  16. White light generation from YAG/YAM:Ce3+, Pr3+, Cr3+ nanophosphors mixed with a blue dye under 340 nm excitation

    International Nuclear Information System (INIS)

    The structural and luminescent properties of Y3Al5O12/Y4Al2O9:Ce3+(0.1%)–Pr3+(0.1%) –Cr3+ (trace impurities) nanophosphors synthesized by a simple hydrothermal method were studied. The crystalline phase was composed of Yttrium Aluminum Garnet (YAG) and Yttrium Aluminum Monoclinic (YAM) depending on the ammonia concentration and annealing temperature. Ammonia increased the stabilization of YAG from 55 wt% to 63 wt% in the samples annealed at 900 °C, and an increment of 83% of the overall emission under 460 nm excitation was observed. Quenching of the emitted signal after annealing at 1100 °C was observed in spite of single YAG crystalline phase stabilization, due to the formation of Ce4+, Pr4+, and color centers. In addition to the green–yellow emission from Ce3+, all samples present a broad red emission band produced by the relaxations from the broad band 4T2 toward the 4A2 energy level of Cr3+ impurities, under 340 nm excitation. By taking advantage of this broad green–yellow–red emission and using a blue dye, white light with CIE coordinates of (0.30, 0.36) under 340 nm excitation was produced. - Highlights: • YAG/YAM:Ce3+, Pr3+, Cr3+ nanophosphors were synthesized with a hydrothermal method. • Ammonia introduced during the synthesis increased the emission of nanophosphors. • White light was obtained by combining the emissions of a blue dye and nanophosphors. • The CIE coordinates for this white light are (0.30, 0.36)

  17. White light generation from YAG/YAM:Ce{sup 3+}, Pr{sup 3+}, Cr{sup 3+} nanophosphors mixed with a blue dye under 340 nm excitation

    Energy Technology Data Exchange (ETDEWEB)

    Oliva, J. [Centro de Investigaciones en Optica, A.P. 1-948, León, Gto 37150, México (Mexico); De la Rosa, E., E-mail: elder@cio.mx [Centro de Investigaciones en Optica, A.P. 1-948, León, Gto 37150, México (Mexico); Diaz-Torres, L.A [Centro de Investigaciones en Optica, A.P. 1-948, León, Gto 37150, México (Mexico); Torres, A. [Universidad Autónoma de Nuevo León, A.P. 126-F, Monterrey, NL 66450, México (Mexico); Salas, P. [Centro de Física Aplicada y Tecnología Avanzada, Universidad Nacional Autónoma de México, A.P. 1-1010, Juriquilla, Qro. 76000, México (Mexico); Meza, O. [Benemérita Universidad Autónoma de Puebla, 4 Sur 104 Centro Historico, 72000 Puebla, México (Mexico)

    2014-10-15

    The structural and luminescent properties of Y{sub 3}Al{sub 5}O{sub 12}/Y{sub 4}Al{sub 2}O{sub 9}:Ce{sup 3+}(0.1%)–Pr{sup 3+}(0.1%) –Cr{sup 3+} (trace impurities) nanophosphors synthesized by a simple hydrothermal method were studied. The crystalline phase was composed of Yttrium Aluminum Garnet (YAG) and Yttrium Aluminum Monoclinic (YAM) depending on the ammonia concentration and annealing temperature. Ammonia increased the stabilization of YAG from 55 wt% to 63 wt% in the samples annealed at 900 °C, and an increment of 83% of the overall emission under 460 nm excitation was observed. Quenching of the emitted signal after annealing at 1100 °C was observed in spite of single YAG crystalline phase stabilization, due to the formation of Ce{sup 4+}, Pr{sup 4+}, and color centers. In addition to the green–yellow emission from Ce{sup 3+}, all samples present a broad red emission band produced by the relaxations from the broad band {sup 4}T{sub 2} toward the {sup 4}A{sub 2} energy level of Cr{sup 3+} impurities, under 340 nm excitation. By taking advantage of this broad green–yellow–red emission and using a blue dye, white light with CIE coordinates of (0.30, 0.36) under 340 nm excitation was produced. - Highlights: • YAG/YAM:Ce{sup 3+}, Pr{sup 3+}, Cr{sup 3+} nanophosphors were synthesized with a hydrothermal method. • Ammonia introduced during the synthesis increased the emission of nanophosphors. • White light was obtained by combining the emissions of a blue dye and nanophosphors. • The CIE coordinates for this white light are (0.30, 0.36)

  18. A worldwide analysis of human exposure to floods by using satellite nighttime lights

    Science.gov (United States)

    Ceola, Serena; Montanari, Alberto; Laio, Francesco

    2015-04-01

    The recent occurrence of flood events across the globe, which represent the first cause of economic losses and human fatalities among natural disasters, has highlighted the urgent need of mitigation strategies to reduce flood risk. To date, expeditious procedures for a worldwide detailed spatio-temporal identification of human exposure to floods are still incomplete. To this end, we propose the use of satellite images of nighttime lights to identify the areas across the globe most at risk for flood damages. Nightlights are indeed a widely used proxy for population density and economic activity. Worldwide nocturnal lights along the river network, available as yearly average values from 1992 to 2012 at 1 km2 resolution, are first analysed from a temporal perspective in order to estimate their temporal trends. Our results revealed that the temporal evolution of nightlights can be reasonably associated with the temporal pattern of human exposure to floods. Nightlights are then correlated with global data of economic losses caused by flooding events. Our outcomes showed that nocturnal lights close to rivers are consistently related to flood damages. In particular, we found that increasing nightlights are associated to flood damage intensification. Our analysis may thus provide valuable information for better understanding the interactions between hydrology and society and identifying priorities for flood risk management.

  19. Multi-3,3'-Bicarbazole-Substituted Arylsilane Host Materials with Balanced Charge Transport for Highly Efficient Solution-Processed Blue Phosphorescent Organic Light-Emitting Diodes.

    Science.gov (United States)

    Sun, Dianming; Zhou, Xiaokang; Li, Huihui; Sun, Xiaoli; Ren, Zhongjie; Ma, Dongge; Yan, Shouke

    2015-08-19

    A series of 3,3'-bicarbazole (mCP)-functionalized tetraphenylsilane derivatives (SimCPx), including bis(3,5-di(9H-carbazol-9-yl)phenyl)diphenylsilane (SimCP2), tris(3,5-di(9H-carbazol-9-yl)phenyl)methylsilane (SimCP3-CH3), tris(3,5-di(9H-carbazol-9-yl)phenyl)phenylsilane (SimCP3-Ph), and tetrakis(3,5-di(9H-carbazol-9-yl)phenyl)silane (SimCP4), serving as bipolar blue hosts for bis[2-(4,6-difluorophenyl)pyridyl-N,C2']iridium(III) (FIrpic), have been synthesized by incorporating different ratios of mCP subunits into a central silicon atom. All of the SimCPx derivatives have wide bandgaps and high triplet energies because of the indirect linkage by silicon between each mCP subunit. The good solubility and high thermal and morphological stability of SimCPx are beneficial for forming amorphous and homogeneous films through solution processing. Density functional theory simulations manifest the better bipolar characteristics for SimCPx using three and four mCP units rather than the represented bipolar host SimCP2. As a result, SimCP4 presents the best electron-transporting ability for charge balance. Consequently, the lowest driving voltage of 4.8 eV, and the favorable maximum efficiencies of 14.2% for external quantum efficiency (28.4 cd A(-1), 13.5 lm W(-1)), are achieved by solution-processed, SimCP4-based blue phosphorescent organic light-emitting diodes as the highest performance among SimCPx, in which 32% improved device efficiencies compared to that of SimCP2 are obtained. It is inspiring to develop efficient bipolar hosts for blue phosphors by just incorporating monopolar carbazole into arylsilanes in two steps. PMID:26252613

  20. Origin of a counterintuitive yellow light-emitting electrochemical cell based on a blue-emitting heteroleptic copper(i) complex.

    Science.gov (United States)

    Weber, Michael D; Garino, Claudio; Volpi, Giorgio; Casamassa, Enrico; Milanesio, Marco; Barolo, Claudia; Costa, Rubén D

    2016-06-01

    This work provides the synthesis, structural characterization, electrochemical and photophysical features, as well as the application in light-emitting electrochemical cells (LECs) of a novel heteroleptic copper(i) complex - [Cu(impy)(POP)][PF6], where impy is 3-(2-methoxyphenyl)-1-(pyridine-2-yl)imidazo[1,5-a]pyridine and POP is bis{2-(diphenylphosphanyl)phenyl}ether. This compound shows blue photoluminescence (PL, λ = 450 nm) in solution and solid-state and excellent redox stability. Despite these excellent features, the electroluminescence (EL) response is located at ∼550 nm. Although the EL spectrum of LECs is typically red-shifted compared to the PL of the electroluminescent material, a shift of ca. 100 nm represents the largest one reported in LECs. To date, the large shift phenomena have been attributed to (i) a change in the nature of the lowest emitting state due to a concentration effect of the films, (ii) a reversible substitution of the ligands due to the weak coordination to the Cu(i), and (iii) a change in the distribution of the excited states due to polarization effects. After having discarded these along with others like the irreversible degradation of the emitter during device fabrication and/or under operation conditions, driving conditions, active layer composition, and changes in the excited states under different external electrical stimuli, we attribute the origin of this unexpected shift to a lack of a thermally activated delayed fluorescence (TADF) process due to the solely ligand-centered character of the excited states. As such, the lack of a charge transfer character in the excited states leads to a blue-fluorescence and yellow-phosphorescence photo- and electro-responses, respectively. This corroborates recent studies focused on the design of TADF for heteroleptic copper(i) complexes. Overall, this work is a clear insight into the design of new copper(i) complexes towards the preparation of blue LECs, which are still unexplored. PMID

  1. Changes in cAMP and cGMP concentration birefringent fibrils and contractile activity accompanying UV and blue light photoavoidance in plasmodia of an albino strain of Physarum polycephalum

    Energy Technology Data Exchange (ETDEWEB)

    Ueda, Tetsuo; Mori Yoshihito; Nakagaki, Toshiyuki; Kobatake, Yonosuke

    1988-02-01

    Photoavoidance by plasmodia of an albino strain of Physarum polycephalum was studied. When the organism was irradiated locally, the protoplasm moved away from the irradiated region. The action spectrum for this avoidance showed three peaks at about 260, 370 and 460 nm. The organism was about one hundred times as sensitive to far UV as to near UV and blue light, and high intensity far-UV caused the gelation of the protoplasm. Irradiation with UV or blue light increased the mean level or the amplitude of oscillation in intracellular cAMP and cGMP concentrations. Upon UV irradiation, birefringent fibrils, presumably microfilaments of F-actin, became thick and numerous, and the plasmodial strand generated a strong tensile force. It is postulated that UV or blue light brings about an increased concentration of cyclic nucleotides which leads to an enhanced local development of contractile fibrils which squeeze protoplasmic sol from the area, resulting in photoavoidance.

  2. Carcinogenesis related to intense pulsed light and UV exposure: an experimental animal study.

    Science.gov (United States)

    Hedelund, L; Lerche, C; Wulf, H C; Haedersdal, M

    2006-12-01

    This study examines whether intense pulsed light (IPL) treatment has a carcinogenic potential itself or may influence ultraviolet (UV)-induced carcinogenesis. Secondly, it evaluates whether UV exposure may influence IPL-induced side effects. Hairless, lightly pigmented mice (n=144) received three IPL treatments at 2-week intervals. Simulated solar radiation was administered preoperatively [six standard erythema doses (SED) four times weekly for 11 weeks] as well as pre- and postoperatively (six SED four times weekly up to 26 weeks). Skin tumors were assessed weekly during a 12-month observation period. Side effects were evaluated clinically. No tumors appeared in untreated control mice or in just IPL-treated mice. Skin tumors developed in UV-exposed mice independently of IPL treatments. The time it took for 50% of the mice to first develop skin tumor ranged from 47 to 49 weeks in preoperative UV-exposed mice (p=0.94) and from 22 to 23 weeks in pre- and postoperative UV-exposed mice (p=0.11). IPL rejuvenation of lightly pigmented skin did not induce pigmentary changes (p=1.00). IPL rejuvenation of UV-pigmented skin resulted in an immediate increased skin pigmentation and a subsequent short-term reduced skin pigmentation (pIPL-induced pigment reduction (p=0.12). No texture changes were observed. Postoperative edema and erythema were increased by preoperative UV exposure (pIPL rejuvenation has no carcinogenic potential itself and does not influence UV-induced carcinogenesis. UV exposure influences the occurrence of side effects after IPL rejuvenation in an animal model. PMID:16964439

  3. Photocurrent response of B12As2 crystals to blue light, and its temperature- dependent electrical characterizations

    OpenAIRE

    R. Gul; CUI, Y.; A. E. Bolotnikov; Camarda, G.S.; S. U. Egarievwe; Hossain, A.; U. N. Roy; G. Yang; Edgar, J. H.; U. Nwagwu; James, R. B.

    2016-01-01

    With the global shortage of 3He gas, researchers worldwide are looking for alternative materials for detecting neutrons. Among the candidate materials, semiconductors are attractive because of their light weight and ease in handling. Currently, we are looking into the suitability of boron arsenide (B12As2) for this specific application. As the first step in evaluating the material qualitatively, the photo-response of B12As2 bulk crystals to light with different wavelengths was examined. The ...

  4. Inactivation of bacteriophage lambda by combined X-ray and U.V.-light exposure

    International Nuclear Information System (INIS)

    Extracellular phage lambda has been successively exposed to X-rays and U.V. light. The plaque-forming ability of the irradiated phages was determined on host cells with different repair capacities. No change in sensitivity was found with a pre-treatment of one type of radiation to lethal damage inflicted by the other. This indicates that a prerequisite for an interaction of different types of radiation is either an active metabolism or repair process occurring during the two radiation exposures. (author)

  5. Blue organic light-emitting diodes with low driving voltage and maximum enhanced power efficiency based on buffer layer MoO{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Khizar-ul-Haq, E-mail: khizar_bhr@yahoo.co [School of Materials Science and Engineering, Shanghai University, Jiading Shanghai 201800 (China); Khan, M.A.; Jiang, X.Y. [School of Materials Science and Engineering, Shanghai University, Jiading Shanghai 201800 (China); Zhang, Z.L. [School of Materials Science and Engineering, Shanghai University, Jiading Shanghai 201800 (China)] [Key Laboratories of Advanced Display and System Applications, Ministry of Education, Shanghai University, Shanghai 200072 (China); Zhang, X.W. [School of Materials Science and Engineering, Shanghai University, Jiading Shanghai 201800 (China); Wei, Bin [School of Materials Science and Engineering, Shanghai University, Jiading Shanghai 201800 (China)] [Key Laboratories of Advanced Display and System Applications, Ministry of Education, Shanghai University, Shanghai 200072 (China); Wei, J.M.; Zhang Liang; Li Jun [School of Materials Science and Engineering, Shanghai University, Jiading Shanghai 201800 (China)

    2009-10-15

    Blue organic light-emitting devices based on wide bandgap host material, 2-(t-butyl)-9, 10-di-(2-naphthyl) anthracene (TBADN), blue fluorescent styrylamine dopant, p-bis(p-N,N-diphenyl-amino-styryl)benzene (DSA-Ph) have been realized by using molybdenum oxide (MoO{sub 3}) as a buffer layer and 4,7-diphenyl-1,10-phenanthroline (BPhen) as the ETL. The typical device structure used was glass substrate/ITO/MoO{sub 3} (5 nm)/NPB (30 nm)/[TBADN: DSA-Ph (3 wt%)](35 nm)/BPhen (12 nm)/LiF (0.8 nm)/Al (100 nm). It was found that the MoO{sub 3}-parallel BPhen-based device shows the lowest driving voltage and highest power efficiency among the referenced devices. At the current density of 20 mA/cm{sup 2}, its driving voltage and power efficiency are 5.4 V and 4.7 Lm/W, respectively, which is independently reduced 46%, and improved 74% compared with those the m-MTDATA-parallel Alq{sub 3} is based on, respectively. The J-V curves of 'hole-only' devices reveal that a small hole injection barrier between MoO{sub 3}-parallel NPB leads to a strong hole injection, resulting low driving voltage and high power efficiency. The results strongly indicate that carrier injection ability and balance shows a key significance in OLED performance.

  6. A new interpretation for performance improvement of high-efficiency vertical blue light-emitting diodes by InGaN/GaN superlattices

    International Nuclear Information System (INIS)

    The effect of InGaN/GaN superlattices (SLs) on quantum efficiency and forward voltage of vertical blue InGaN/GaN multiple quantum well (MQW) light-emitting diodes (LED) grown on Si substrate has been experimentally and theoretically investigated. We have prepared two LED samples, in which the 30 and 45 periods of SLs are inserted between MQW active layers and n-GaN layer, respectively. Electroluminescence measurement shows that the LED with 45 periods of SLs has higher quantum efficiency but lower forward voltage. It is observed that V-shaped pits grow up in size with an increase in SLs period number by means of scan transmission electron microscope and secondary ion mass spectrometry. Further numerical simulations confirm that the performance improvement of LED by SLs is mainly ascribed to enhancing hole injection from the V-shaped pits

  7. Performance improvement of blue light-emitting diodes with an AlInN/GaN superlattice electron-blocking layer

    Institute of Scientific and Technical Information of China (English)

    Zhao Fang; Yao Guang-Rui; Song Jing-Jing; Ding Bin-Bin; Xiong Jian-Yong; Su Chen; Zheng Shu-Wen

    2013-01-01

    The characteristics of a blue light-emitting diode (LED) with an AlInN/GaN superlattice (SL) electron-blocking layer (EBL) are analyzed numerically.The cartier concentrations in the quantum wells,energy band diagrams,electrostatic fields,and internal quantum efficiency are investigated.The results suggest that the LED with an AlInN/GaN SL EBL has better hole injection efficiency,lower electron leakage,and smaller electrostatic fields in the active region than the LED with a conventional rectangular AlGaN EBL or a A1GaN/GaN SL EBL.The results also indicate that the efficiency droop is markedly improved when an AlInN/GaN SL EBL is used.

  8. Efficient polymer light-emit ting diodes with violet blue emission based on blends of PSiF6-PPP and PSiFC6C6

    Institute of Scientific and Technical Information of China (English)

    TIAN Renyu; MO Yueqi; PENG Junbiao

    2006-01-01

    Efficient polymer light-emitting diodes (PLEDs) with violet blue emission were fabricated using blends of copolymers of paraphenylene-cosilafluorene (PSiF6-PPP) and polymer of poly (9,9'alkyl-3,6-silafluorene) (PSiFC6C6). The performances of the devices are sensitive to the blend ratio.When the mass ratio of PSiF6-PPP to PSiFC6C6 is 1.96% at luminance of 105 cd.m-2, its electroluminescent (EL) spectrum peaks at 398 nm and full width at half maximum is 67 nm. The improvements of the device performances were due to the energy transfer from PSiFC6C6 to PSiF6-PPP and the balanced injection of electrons and holes.

  9. Surfactant-assisted hydrothermal fabrication and visible-light-driven photocatalytic degradation of methylene blue over multiple morphological BiVO4 single-crystallites

    International Nuclear Information System (INIS)

    Monoclinic BiVO4 single-crystallites with polyhedral, rod-like, tubular, leaf-like, and spherical morphologies have been fabricated using the triblock copolymer P123-assisted hydrothermal strategy with bismuth nitrate and ammonium metavanadate as metal source and various bases as pH adjustor. The physicochemical properties of the materials were characterized by means of the XRD, TGA/DSC, Raman, HRSEM, HRTEM/SAED, XPS, and UV-vis techniques. The photocatalytic activities of the as-fabricated BiVO4 samples were measured for the photodegradation of methylene blue (MB) under visible-light irradiation. It is shown that factors, such as the pH value of precursor solution, the introduction of surfactant, the nature of alkaline source, and the hydrothermal temperature, have a crucial influence on the particle architecture of the BiVO4 product. Among the as-fabricated BiVO4 samples, the ones derived hydrothermally with P123 at pH = 6 or 10 possessed excellent optical absorption performance both in UV- and visible-light regions and hence showed outstanding photocatalytic activities for the addressed reaction. The unusually high visible-light-driven catalytic performance of monoclinically crystallized rod-like and tubular BiVO4 single-crystallites is associated with the higher surface areas and concentrations of surface oxygen defects, and unique particle morphologies. The possible formation mechanisms of such multiple morphological BiVO4 materials have also been discussed.

  10. Novel Pd/TiO2 nanocomposite prepared by modified sol–gel method for photocatalytic degradation of methylene blue dye under visible light irradiation

    International Nuclear Information System (INIS)

    Highlights: •Chitosan (CS) has no obvious effect on the crystallizing process of the main form, anatase. •Crystallite size of TiO2/CS (18 nm) was smaller than that of pure TiO2 (116 nm). •CS prevents the agglomeration of both TiO2 and Pd/TiO2 with dispersion of Pd over TiO2. •CS and Pd significantly improved the visible light photocatalytic activity of TiO2. -- Abstract: TiO2 nanoparticles were prepared using the modified sol–gel method. TiO2 impregnated with Pd and/or chitosan (CS) was prepared using the impregnation method. The Pd/TiO2 composite photocatalyst was characterized by XRD, TEM, UV–Vis, Pl, and BET. A methylene blue dye (MB) was used as a model pollutant to study the photocatalytic activity of TiO2 under visible light irradiation. The influence of the type and amount of catalyst as well as the initial concentration of MB was investigated. The results indicate that CS can effectively prevent the agglomeration of TiO2 nanoparticles. UV–Vis spectra demonstrated that the composite’s ability to absorb visible light is greatly improved. The photocatalytic degradation of MB was found to follow first-order kinetics. Recycling experiments confirmed the relative stability of the catalyst

  11. Doped and non-doped organic light-emitting diodes based on a yellow carbazole emitter into a blue-emitting matrix

    CERN Document Server

    Choukri, H; Forget, S; Chenais, S; Castex, M C; Geffroy, B; Ades, D; Siove, A; Choukri, Hakim; Fischer, Alexis; Forget, Sebastien; Chenais, Sebastien; Castex, Marie-Claude; Geffroy, Bernard; Ades, Dominique; Siove, Alain

    2007-01-01

    A new carbazole derivative with a 3,3'-bicarbazyl core 6,6'-substituted by dicyanovinylene groups (6,6'-bis(1-(2,2'-dicyano)vinyl)-N,N'-dioctyl-3,3'-bicarbazyl; named (OcCz2CN)2, was synthesized by carbonyl-methylene Knovenagel condensation, characterized and used as a component of multilayer organic light-emitting diodes (OLEDs). Due to its -donor-acceptor type structure, (OcCz2CN)2 was found to emit a yellow light at max=590 nm (with the CIE coordinates x=0.51; y = 0.47) and was used either as a dopant or as an ultra-thin layer in a blue-emitting matrix of 4,4'-bis(2,2'-diphenylvinyl)-1,1'-biphenyl (DPVBi). DPVBi (OcCz2CN)2-doped structure exhibited, at doping ratio of 1.5 weight %, a yellowish-green light with the CIE coordinates (x = 0.31; y = 0.51), an electroluminescence efficiency EL=1.3 cd/A, an external quantum efficiency ext= 0.4 % and a luminance L= 127 cd/m2 (at 10 mA/cm2) whereas for non-doped devices utilizing the carbazolic fluorophore as a thin n...

  12. Influence of laser lift-off on optical and structural properties of InGaN/GaN vertical blue light emitting diodes

    Directory of Open Access Journals (Sweden)

    M. H. Doan

    2012-06-01

    Full Text Available The influences of the laser lift-off (LLO process on the InGaN/GaN blue light emitting diode (LED structures, grown on sapphire substrates by low-pressure metalorganic chemical vapor deposition, have been comprehensively investigated. The vertical LED structures on Cu carriers are fabricated using electroplating, LLO, and inductively coupled plasma etching processes sequentially. A detailed study is performed on the variation of defect concentration and optical properties, before and after the LLO process, employing high-resolution transmission electron microscopy (HRTEM, scanning electron microscopy (SEM observations, cathodoluminescence (CL, photoluminescence (PL, and high-resolution X-ray diffraction (HRXRD measurements. The SEM observations on the distribution of dislocations after the LLO show well that even the GaN layer near to the multiple quantum wells (MQWs is damaged. The CL measurements reveal that the peak energy of the InGaN/GaN MQW emission exhibits a blue-shift after the LLO process in addition to a reduced intensity. These behaviors are attributed to a diffusion of indium through the defects created by the LLO and creation of non-radiative recombination centers. The observed phenomena thus suggest that the MQWs, the active region of the InGaN/GaN light emitting diodes, may be damaged by the LLO process when thickness of the GaN layer below the MQW is made to be 5 μm, a conventional thickness. The CL images on the boundary between the KrF irradiated and non-irradiated regions suggest that the propagation of the KrF laser beam and an accompanied recombination enhanced defect reaction, rather than the propagation of a thermal shock wave, are the main origin of the damage effects of the LLO process on the InGaN/GaN MQWs and the n-GaN layer as well.

  13. Roles for blue light, jasmonate and nitric oxide in the regulation of dormancy and germination in wheat grain (Triticum aestivum L.).

    Science.gov (United States)

    Jacobsen, John V; Barrero, Jose M; Hughes, Trijntje; Julkowska, Magdalena; Taylor, Jennifer M; Xu, Qian; Gubler, Frank

    2013-07-01

    Abscisic acid (ABA) plays a central role in seed dormancy and transcriptional regulation of genes coding for ABA biosynthetic and degradation enzymes is responsible for control of ABA content. However, little is known about signalling both before and after ABA regulation, in particular, how environmental signals are perceived and transduced. We are interested in these processes in cereal grains, particularly in relation to the development of strategies for controlling pre-harvest sprouting in barley and wheat. Our previous studies have indicated possible components of dormancy control and here we present evidence that blue light, nitric oxide (NO) and jasmonate are major controlling elements in wheat grain. Using microarray and pharmacological studies, we have found that blue light inhibits germination in dormant grain and that methyl jasmonate (MJ) and NO counteract this effect by reducing dormancy. We also present evidence that NO and jasmonate play roles in dormancy control in vivo. ABA was reduced by MJ and this was accompanied by reduced levels of expression of TaNCED1 and increased expression of TaABA8'OH-1 compared with dormant grain. Similar changes were caused by after-ripening. Analysis of global gene expression showed that although jasmonate and after-ripening caused important changes in gene expression, the changes were very different. While breaking dormancy, MJ had only a small number of target genes including gene(s) encoding beta-glucosidase. Our evidence indicates that NO and MJ act interdependently in controlling reduction of ABA and thus the demise of dormancy. PMID:23588419

  14. Synthesis of small silver nanoparticles under light radiation by fungus Penicillium oxalicum and its application for the catalytic reduction of methylene blue

    Energy Technology Data Exchange (ETDEWEB)

    Du, Liangwei, E-mail: dulily9@163.com [State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, Guangxi University, 100 Daxue Road, Nanning 530004, Guangxi (China); College of Chemistry and Chemical Engineering, Guangxi University, 100 Daxue Road, Nanning 530004, Guangxi (China); Xu, Qiuhong; Huang, Meiying [State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, Guangxi University, 100 Daxue Road, Nanning 530004, Guangxi (China); College of Chemistry and Chemical Engineering, Guangxi University, 100 Daxue Road, Nanning 530004, Guangxi (China); Xian, Liang [State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, Guangxi University, 100 Daxue Road, Nanning 530004, Guangxi (China); College of Life Science and Technology, Guangxi University, 100 Daxue Road, Nanning 530004, Guangxi (China); Feng, Jia-Xun, E-mail: jiaxunfeng@sohu.com [State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, Guangxi University, 100 Daxue Road, Nanning 530004, Guangxi (China); College of Life Science and Technology, Guangxi University, 100 Daxue Road, Nanning 530004, Guangxi (China)

    2015-06-15

    At present, green and efficient synthetic strategies have been gaining great interest for the synthesis of metal nanoparticles. In this study, the synthesis of extracellular silver nanoparticles (AgNPs) under light radiation was described using the cell filtrate of Penicillium oxalicum 1–208. The pH effect of the cell filtrate on nanosynthesis was investigated by visual observation, ultraviolet–visible absorption spectroscopy, dynamic light scattering and zeta potential. The results showed that the pH of the cell filtrate affected the time of nanosynthesis, and the size, size distribution and stability of the synthesized nanoparticles. The AgNPs synthesized at pH 8.0 and 12.0 were further characterized by X-ray diffraction, selected area electron diffraction, energy-dispersive X-ray spectroscopy and transmission electron microscopy. The synthesized AgNPs were spherical in shape, crystalline in nature and preferentially oriented in (111) plane. Small AgNPs with an average particle size of about 4 nm were successfully synthesized at pH 12.0 and well dispersed in solution without obvious aggregation. Furthermore, the AgNPs synthesized at pH 8.0 were used as catalyst and exhibited excellent catalytic activity for the reduction of methylene blue in the presence of NaBH{sub 4} at ambient temperature. - Highlights: • Extracellular silver nanoparticles were synthesized using Penicillium oxalicum assisted by simulated sunlight. • The pH of the cell filtrate affected the synthesis of silver nanoparticles. • The silver nanoparticles were more stable in weakly alkaline and alkaline solutions. • Small silver nanoparticles with good dispersibility and stability were rapidly synthesized at pH 12.0. • The reduction of methylene blue was instantly completed with silver nanoparticles synthesized at pH 8.0 used as catalyst.

  15. Synthesis of small silver nanoparticles under light radiation by fungus Penicillium oxalicum and its application for the catalytic reduction of methylene blue

    International Nuclear Information System (INIS)

    At present, green and efficient synthetic strategies have been gaining great interest for the synthesis of metal nanoparticles. In this study, the synthesis of extracellular silver nanoparticles (AgNPs) under light radiation was described using the cell filtrate of Penicillium oxalicum 1–208. The pH effect of the cell filtrate on nanosynthesis was investigated by visual observation, ultraviolet–visible absorption spectroscopy, dynamic light scattering and zeta potential. The results showed that the pH of the cell filtrate affected the time of nanosynthesis, and the size, size distribution and stability of the synthesized nanoparticles. The AgNPs synthesized at pH 8.0 and 12.0 were further characterized by X-ray diffraction, selected area electron diffraction, energy-dispersive X-ray spectroscopy and transmission electron microscopy. The synthesized AgNPs were spherical in shape, crystalline in nature and preferentially oriented in (111) plane. Small AgNPs with an average particle size of about 4 nm were successfully synthesized at pH 12.0 and well dispersed in solution without obvious aggregation. Furthermore, the AgNPs synthesized at pH 8.0 were used as catalyst and exhibited excellent catalytic activity for the reduction of methylene blue in the presence of NaBH4 at ambient temperature. - Highlights: • Extracellular silver nanoparticles were synthesized using Penicillium oxalicum assisted by simulated sunlight. • The pH of the cell filtrate affected the synthesis of silver nanoparticles. • The silver nanoparticles were more stable in weakly alkaline and alkaline solutions. • Small silver nanoparticles with good dispersibility and stability were rapidly synthesized at pH 12.0. • The reduction of methylene blue was instantly completed with silver nanoparticles synthesized at pH 8.0 used as catalyst

  16. Methylene blue and 4-chloro phenol degradation by photo catalysis with ultraviolet light, using TiO2 as catalyst

    International Nuclear Information System (INIS)

    Within the decontamination and remediation processes of the contaminated waters, as the refining or tertiary processes are the Advanced Oxidation Technologies. Among this technology is the heterogeneous photo catalysis, which is the object of this work to de grate 4-chloro phenol and methylene blue, using as semiconductor commercial titanium dioxide (TiO2). On the degradation the combination is exposed in the use of TiO2 under gamma irradiation of 60Co at different doses 400, 500, 800, 1000 and 1500 kGy. The organic compounds degradation was determined and the results show that to more radiation dose, the material is modified in such way that shows a major absorption of the organic compound, in the same way it is determined that to more dose which undergoes the TiO2 generally a major degradation is observed, but also it is has to give a more time of previous stabilization, for that the degradation is observed of better way. (Author)

  17. Synthesis of the graphene-ZnTiO3 nanocomposite for solar light assisted photodegradation of methylene blue

    Science.gov (United States)

    Gayathri, Shunmugiah; Jayabal, Palanisamy; Kottaisamy, Muniasamy; Ramakrishnan, Veerabahu

    2015-10-01

    Cubic and hexagonal phase zinc titanate (ZT) nanoparticles were synthesized via simple chemical precipitation method. The graphene-zinc titanate (GZT) nanocomposites were prepared by using the synthesized ZT nanoparticles and graphene oxide as precursors. The synthesized materials were characterized by various spectroscopic techniques. The agglomerated ZT nanoparticles anchored on graphene sheets are clearly visible in the field emission scanning electron micrograph (FE-SEM) image. Raman mapping of the GZT nanocomposites revealed the homogeneity and distribution of ZT nanoparticles on the surface of graphene. The UV-visible absorption and photoluminescence spectra of the samples suggest that the GZT nanocomposites can be used as efficient photocatalysts to remove organic dye from water. The photocatalytic activity of the synthesized photocatalysts was evaluated by the photodegradation of methylene blue dye under sunlight irradiation. The enhanced absorption in the visible region of the GZT samples compared to the ZT samples played a vital role during the photocatalysis. The hexagonal phase GZT nanocomposite displayed remarkable photocatalytic activity compared to the bare ZT nanoparticles. The possible electron transfer mechanism for graphene-ZT interface during the photocatalysis process is also proposed. Furthermore, the reusability and stability tests for the prepared photocatalysts were made and reported.

  18. Construction and characterization of a forward subtracted library of blue mussels Mytilus edulis for the identification of gene transcription signatures and biomarkers of styrene exposure

    International Nuclear Information System (INIS)

    Highlights: ► Transcription responses in blue mussels exposed to styrene have been studied by SSH. ► 1440 Clones were obtained from which 287 were sequenced. ► Immune system, cancer-related and ribosomal genes identified as upregulated genes. ► Chitin and β-1-3-glucan metabolism genes highly represented in subtracted library. -- Abstract: Transcriptional profiling can elucidate adaptive/toxicity pathways participating in achieving homeostasis or leading to pathogenesis in marine biota exposed to chemical substances. With the aim of analyzing transcriptional responses in the mussel Mytilus edulis exposed to the corrosive and putatively carcinogenic hydrocarbon styrene (3–5 ppm, 3 days), a forward subtracted (SSH) cDNA library was produced. Female mussels were selected and digestive gland mRNA was isolated. A library with 1440 clones was produced and a total of 287 clones were sequenced, 53% being identified through BlastN analysis against Mytibase and DeepSeaVent databases. Those genes included GO terms such as ‘response to drugs’, ‘immune defense’ and ‘cell proliferation’. Furthermore, sequences related to chitin and beta-1-3-glucan metabolism were also up-regulated by styrene. Many of the obtained sequences could not be annotated constituting new mussel sequences. In conclusion, this SSH study reveals novel sequences useful to generate molecular biomarkers of styrene exposure in mussels

  19. Influence of blue and red light illumination on the holographic storage in an azopolyester–PMMA blend

    DEFF Research Database (Denmark)

    Berges, C.; Díez, I.; Javakhishvili, Irakli;

    2014-01-01

    Volume holographic polarization gratings have been stored in thick films of blends of a side-chain azobenzene polyester and a poly(methyl methacrylate) (PMMA) homopolymers. The azobenzene content in the blend is 0.2wt%, and the holograms are recorded by using 2ms 4mJ/cm2 488nm light pulses...

  20. Highly efficient blue-green quantum dot light-emitting diodes using stable low-cadmium quaternary-alloy ZnCdSSe/ZnS core/shell nanocrystals.

    Science.gov (United States)

    Shen, Huaibin; Wang, Sheng; Wang, Hongzhe; Niu, Jinzhong; Qian, Lei; Yang, Yixing; Titov, Alexandre; Hyvonen, Jake; Zheng, Ying; Li, Lin Song

    2013-05-22

    High-quality blue-green emitting ZnxCd(1-x)S(1-y)Se(y)/ZnS core/shell quantum dots (QDs) have been synthesized by a phosphine-free method. The quantum yields of as-synthesized ZnxCd(1-x)S(1-y)Se(y)/ZnS core/shell QDs can reach 50-75% with emissions between 450 and 550 nm. The emissions of such core/shell QDs are not susceptible to ligand loss through the photostability test. Blue-green light-emitting diodes (LEDs) based on the low-cadmium ZnxCd(1-x)S(1-y)Se(y)/ZnS core/shell QDs have been successfully demonstrated. Composite films of poly[9,9-dioctylfluorene-co-N-[4-(3-methylpropyl)]-diphenylamine] (TFB) and ZnO nanoparticle layers were chosen as the hole-transporting and the electron-transporting layers, respectively. Highly bright blue-green QD-based light-emitting devices (QD-LEDs) showing maximum luminance up to 10000 cd/m(2), in particular, the blue QD-LEDs show an unprecedentedly high brightness over 4700 cd/m(2) and peak external quantum efficiency (EQE) of 0.8%, which is the highest value ever reported. These results signify a remarkable progress in QD-LEDs and offer a practicable platform for the realization of QD-based blue-green display and lighting. PMID:23633527

  1. Impact of Colored Light on Cardiorespiratory Coordination

    Directory of Open Access Journals (Sweden)

    Friedrich Edelhäuser

    2013-01-01

    Full Text Available Background. Light exposure to the eye can influence different physiological functions, for example, the suprachiasmatic nucleus (SCN. By affecting the autonomic nervous system, the SCN may influence the heart rate variability (HRV. Standardized colored light exposure alters HRV but the results are inconsistent. In this study we investigated the effects of nonstandardized red light (approx. 640 nm and blue (approx. 480 nm light (approx. 50 lx on cardiorespiratory coordination and HRV. Methods. 17 healthy subjects (7 males, age: 26.5 ± 6.2 years were exposed to the following sequence (10 minutes each: daylight-red light-daylight-blue light-daylight. Red and blue lights were created by daylight passing through colored glass panes. Spectral measures of HRV (LF: low frequency, HF: high frequency oscillations, and sympathovagal balance LF/HF and measures of cardiorespiratory coordination (HRR: heart respiration ratio, PCR: phase coordination ratio were analyzed. Results. The LF component increased and the HF component decreased after red light. Consequently, LF/HF increased after red light. Furthermore, during red light HRR and PCR confined to 4 : 1, that is, 4 heartbeats during one respiratory cycle. Conclusion. Nonstandardized red and blue lights are able to alter the autonomic control reflected by HRV as well as cardiorespiratory coordination.

  2. Blue tits are ultraviolet tits

    OpenAIRE

    Hunt, S; Bennett, A.T.D.; Cuthill, I. C.; Griffiths, R.

    1998-01-01

    The blue tit (Parus caeruleus) has been classified as sexually monochromatic. This classification is based on human colour perception yet, unlike humans, most birds have four spectrally distinct classes of cone and are visually sensitive to wavelengths in the near-ultraviolet (300 to 400 nm). Reflectance spectrophotometry reveals that blue tit plumage shows considerable reflection of UV light. For example, the blue crest shows peak reflectance at wavelengths around 352 nm. Furthermore, the bl...

  3. HCN1 Channels Enhance Rod System Responsivity in the Retina under Conditions of Light Exposure.

    Directory of Open Access Journals (Sweden)

    Vithiyanjali Sothilingam

    Full Text Available Vision originates in rods and cones at the outer retina. Already at these early stages, diverse processing schemes shape and enhance image information to permit perception over a wide range of lighting conditions. In this work, we address the role of hyperpolarization-activated and cyclic nucleotide-gated channels 1 (HCN1 in rod photoreceptors for the enhancement of rod system responsivity under conditions of light exposure.To isolate HCN1 channel actions in rod system responses, we generated double mutant mice by crossbreeding Hcn1-/- mice with Cnga3-/- mice in which cones are non-functional. Retinal function in the resulting Hcn1-/- Cnga3-/- animals was followed by means of electroretinography (ERG up to the age of four month. Retinal imaging via scanning laser ophthalmoscopy (SLO and optical coherence tomography (OCT was also performed to exclude potential morphological alterations.This study on Hcn1-/- Cnga3-/- mutant mice complements our previous work on HCN1 channel function in the retina. We show here in a functional rod-only setting that rod responses following bright light exposure terminate without the counteraction of HCN channels much later than normal. The resulting sustained signal elevation does saturate the retinal network due to an intensity-dependent reduction in the dynamic range. In addition, the lack of rapid adaptational feedback modulation of rod photoreceptor output via HCN1 in this double mutant limits the ability to follow repetitive (flicker stimuli, particularly under mesopic conditions.This work corroborates the hypothesis that, in the absence of HCN1-mediated feedback, the amplitude of rod signals remains at high levels for a prolonged period of time, leading to saturation of the retinal pathways. Our results demonstrate the importance of HCN1 channels for regular vision.

  4. Light guide production for LBNE and the effects of UV exposure on VUV waveshifter efficiency

    International Nuclear Information System (INIS)

    The Long-Baseline Neutrino Experiment (LBNE) Project is expected to provide facilities that will enable a program in neutrino physics that can measure fundamental physical parameters, explore physics beyond the Standard Model and better elucidate the nature of matter and anti-matter. The LBNE Photon Detection subsystem is primarily designed to detect the scintillation photons produced at 128 nm as ionizing particles traverse the liquid argon. The LBNE reference design for the photon detector subsystem uses adiabatic light guides consisting of cast acrylic bars whose surface is embedded with waveshifter to convert the VUV 128 nm photons into the sensitive optical range of silicon photomultipliers (SiPMs). In this investigation we first describe our methods for manufacturing light guides. We then describe our testing program to determine the effects of UV radiation on the waveshifter efficiency. We find that UV radiation from fluorescent lights does not degrade waveshifter efficiency significantly in 96 hours of exposure, but that waveshifter quickly deteriorates when exposed to the UV radiation in sunlight

  5. Experimental limit on the blue shift of the frequency of light implied by a q-nonlinearity

    OpenAIRE

    Man'ko, V. I.; Tino, G. M.

    1995-01-01

    We discuss the implications of an experiment in which the frequencies of two laser beams are compared for different intensities in order to search for a dependence of the frequency of light on its intensity. Since no such dependence was found it is possible to place bounds on a description of the electromagnetic field in terms of q-oscillators. We conclude that the value of the nonlinearity parameter is smaller than $10^{-17}~$.

  6. Blue and white light emission in Tm3+ and Tm3+/Dy3+ doped zinc phosphate glasses upon UV light excitation

    Science.gov (United States)

    Meza-Rocha, A. N.; Speghini, A.; Lozada-Morales, R.; Caldiño, U.

    2016-08-01

    A spectroscopic study based on photoluminescence spectra and decay time profiles in Tm3+ and Tm3+/Dy3+ doped Zn(PO3)2 glasses is reported. The Tm3+ doped Zn(PO3)2 glass, upon 357 nm excitation, exhibits blue emission with CIE1931 chromaticity coordinates, x = 0.157 and y = 0.030, and color purity of about 96%. Under excitations at 348, 352 and 363 nm, which match with the emissions of AlGaN and GaN based LEDs, the Tm3+/Dy3+ co-doped Zn(PO3)2 glass displays natural white, bluish white and cool white overall emissions, with correlated color temperature values of 4523, 10700 and 7788 K, respectively, depending strongly on the excitation wavelength. The shortening of the Dy3+ emission decay time in presence of Tm3+ suggests that Dy3+→Tm3+ non-radiative energy transfer occurs. By using the Inokuti-Hirayama model, it is inferred that an electric quadrupole-quadrupole interaction might be the dominant mechanism involved in the energy transfer. The efficiency and probability of this energy transfer are 0.12 and 126.70 s-1, respectively.

  7. Enhanced orange-red emission from KSrVO4:Sm3+ nanophosphor for possible application in blue light-emitting diode based white LED

    International Nuclear Information System (INIS)

    In this paper, the combustion synthesis and photoluminescence properties of Sm3+ doped KSrVO4 nanophosphors are reported. The samples were characterized by different techniques such as x-ray powder diffraction, transmission electron microscopy, UV–vis spectrophotometry and photoluminescence spectroscopy. The lattice parameters were calculated as a=7.4688 (4) A-ring ´, b=5.8171 (4) A-ring ´, c=9.9490 (5) A-ring ´ and V=432.2485 (5) Ǻ3. The average grain size of the samples was estimated as 42 nm using the modified Scherrer’s equation. Under near UV excitation, the sharp emission line at 560, 600, 646 and 704 nm due to characteristic transitions of Sm3+ were observed. The maximum PL emission intensity was observed at 1.5 mol.% of the Sm3+ ions. The band gap of the phosphor was calculated from diffused reflectance data and was found to be 3.74 eV. The CIE 1931 chromaticity coordinates (x, y) of the phosphor were (0.61, 0.39), in a shade of orange-red color. The potential applications of this material as a down conversion phosphor under blue light excitation were evaluated for possible application as a high color-purity phosphor in light emitting diodes (LEDs) that can fill the 590–600 nm gap. (paper)

  8. Theoretical studies on light emission characteristics of high-efficiency BInGaN/GaN quantum well structures with blue spectral range

    Science.gov (United States)

    Park, Seoung-Hwan; Ahn, Doyeol

    2016-08-01

    Light emission characteristics of blue BxInyGa1-x-y N/GaN quantum well (QW) structures were using the multiband effective-mass theory. The In composition (y) to give the transition wavelength of 440 nm is reduced with the inclusion of the B composition (x). We find that the spontaneous emission peak rapidly increases with increasing x. In particular, the peak intensity of the BInGaN/GaN QW structure with x = 0.18 and y = 0.008 is about twice larger than that of the conventional InGaN/GaN QW structure. This can be explained by the fact that the internal field (-0.40 MV/cm) in the BInGaN well is In greatly reduced, compared to that (-1.04 MV/cm) in the conventional InGaN well. Also, the strain (-1.7%) in the BInGaN well is shown to be reduced slightly, compare to that (-2.0%) in InGaN well. Hence, we expect that BInGaN/GaN QW structures with a reduced strain can be used as a light source with a high efficiency.

  9. Efficient blue-green and green electroluminescent devices obtained by doping iridium complexes into hole-block material as supplementary light-emitting layer

    International Nuclear Information System (INIS)

    In this work, organic electroluminescent (EL) devices with dominant and supplementary light-emitting layers (EMLs) were designed to further improve the EL performances of two iridiumIII-based phosphorescent complexes, which have been reported to provide EL devices with slow EL efficiency roll-off. The widely used hole-block material 2,2′,2''-(1,3,5-Benzinetriyl)-tris(1-phenyl-1-H-benzimidazole) (TPBi) was selected as host material to construct the supplementary EML. Compared with single-EML devices, double-EMLs devices showed higher EL efficiencies, higher brightness, and lower operation voltage attributed to wider recombination zone and better balance of carriers. In addition, the insertion of supplementary EML is instrumental in facilitating carriers trapping, thus improving the color purity. Finally, high performance blue-green and green EL devices with maximum current efficiencies of 35.22 and 90.68 cd/A, maximum power efficiencies of 26.36 and 98.18 lm/W, and maximum brightness of 56,678 and 112,352 cd/m2, respectively, were obtained by optimizing the doping concentrations. Such a device design strategy extends the application of a double EML device structure and provides a chance to simplify device fabrication processes. -- Highlights: • Electroluminescent devices with supplementary light-emitting layer were fabricated. • Doping concentrations and thicknesses were optimized. • Better balance of holes and electrons causes the enhanced efficiency. • Improved carrier trapping suppresses the emission of host material

  10. Scattering of light by colloidal aluminosilicate particles produces the unusual sky-blue color of Rio Celeste (Tenorio volcano complex, Costa Rica.

    Directory of Open Access Journals (Sweden)

    Erick Castellón

    Full Text Available Río Celeste (Sky-Blue River in Tenorio National Park (Costa Rica, a river that derives from the confluence and mixing of two colorless streams--Río Buenavista (Buenavista River and Quebrada Agria (Sour Creek--is renowned in Costa Rica because it presents an atypical intense sky-blue color. Although various explanations have been proposed for this unusual hue of Río Celeste, no exhaustive tests have been undertaken; the reasons hence remain unclear. To understand this color phenomenon, we examined the physico-chemical properties of Río Celeste and of the two streams from which it is derived. Chemical analysis of those streams with ion-exchange chromatography (IC and inductively coupled plasma atomic emission spectroscopy (ICP-OES made us discard the hypothesis that the origin of the hue is due to colored chemical species. Our tests revealed that the origin of this coloration phenomenon is physical, due to suspended aluminosilicate particles (with diameters distributed around 566 nm according to a lognormal distribution that produce Mie scattering. The color originates after mixing of two colorless streams because of the enlargement (by aggregation of suspended aluminosilicate particles in the Río Buenavista stream due to a decrease of pH on mixing with the acidic Quebrada Agria. We postulate a chemical mechanism for this process, supported by experimental evidence of dynamic light scattering (DLS, zeta potential measurements, X-ray diffraction and scanning electron microscopy (SEM with energy-dispersive spectra (EDS. Theoretical modeling of the Mie scattering yielded a strong coincidence between the observed color and the simulated one.

  11. A novel theoretical model for broadband blue InGaN/GaN superluminescent light emitting diodes

    International Nuclear Information System (INIS)

    A broadband superluminescent light emitting diode with In0.2Ga0.8N/GaN multiple quantum wells (MQWs) active region is investigated. The investigation is based on a theoretical model which includes the calculation of electronic states of the structure, rate equations, and the spectral radiation power. Two rate equations corresponding to MQW active region and separate confinement heterostructures layer are solved self-consistently with no-k selection wavelength dependent gain and quasi-Fermi level functions. Our results show that the superluminescence started in a current of ∼120 mA (∼7.5 kA/Cm2) at 300 K. The range of peak emission wavelengths for different currents is 423–426 nm and the emission bandwidth is ∼5 nm in the superluminescence regime. A maximum light output power of 7.59 mW is obtained at 600 mA and the peak modal gain as a function of current indicates logarithmic behavior. Also, the comparison of our calculated results with published experimental data is shown to be in good agreement

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

    International Nuclear Information System (INIS)

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

  13. Vitamin B12 enhances the phase-response of circadian melatonin rhythm to a single bright light exposure in humans.

    Science.gov (United States)

    Hashimoto, S; Kohsaka, M; Morita, N; Fukuda, N; Honma, S; Honma, K

    1996-12-13

    Eight young males were subjected to a single blind cross-over test to see the effects of vitamin B12 (methylcobalamin; VB12) on the phase-response of the circadian melatonin rhythm to a single bright light exposure. VB12 (0.5 mg/day) or vehicle was injected intravenously at 1230 h for 11 days, which was followed by oral administration (2 mg x 3/day) for 7 days. A serial blood sampling was performed under dim light condition (less than 200 lx) and plasma melatonin rhythm was determined before and after a single bright light exposure (2500 lx for 3 h) at 0700 h. The melatonin rhythm before the light exposure showed a smaller amplitude in the VB12 trial than in the placebo. The light exposure phase-advanced the melatonin rhythm significantly in the VB12 trail, but not in the placebo. These findings indicate that VB12 enhances the light-induced phase-shift in the human circadian rhythm. PMID:8981490

  14. Synthesis and properties of (Yb, N)-TiO2 photocatalyst for degradation of methylene blue (MB) under visible light irradiation

    International Nuclear Information System (INIS)

    Highlights: • The (Yb, N)-TiO2 nanoparticles were prepared and characterized. • The spectrum absorption region of (Yb, N)-TiO2 is red-shifted to visible light. • The recombination of the photo-generated electron–hole pairs of (Yb, N)-TiO2 is suppressed. • The photocatalytic activity of (Yb, N)-TiO2 is more higher than that of TiO2-P25, N-TiO2 and the Yb-TiO2. - Abstract: (Yb, N)-TiO2 photocatalyst has been synthesized by sol–gel method combined with microwave chemical synthesis. Also, the efficiency of the (Yb, N)-TiO2 as a photocatalyst for the degradation of methylene blue (MB) using visible light irradiation has been evaluated. The prepared samples were characterized by XRD, TEM, XPS, UV–vis-DRS and PL. The results show that the (Yb, N)-TiO2 photocatalyst has the anatase TiO2 crystalline phase. The TEM micrograph demonstrated that the average particle size of the sample was about 12 nm. The band-gap energy absorption edge shifted to longer wavelength as compared to commercial TiO2-P25, N-TiO2 and the Yb-TiO2 prepared by our group. Results of degradation revealed that the (Yb, N)-TiO2 has shown much more higher photocatalytic activity than that of the TiO2-P25, the N-TiO2 and the Yb-TiO2 under the visible light

  15. Synthesis and properties of (Yb, N)-TiO{sub 2} photocatalyst for degradation of methylene blue (MB) under visible light irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, J., E-mail: zhj@ynu.edu.cn [Yunnan Key Laboratory of Micro/Nano Materials & Technology, Yunnan University, Kunming 650091 (China); School of Physical Science and Technology, Yunnan University, Kunming 650091 (China); Xu, L.J., E-mail: 825891915@qq.com [Yunnan Key Laboratory of Micro/Nano Materials & Technology, Yunnan University, Kunming 650091 (China); School of Physical Science and Technology, Yunnan University, Kunming 650091 (China); Zhu, Z.Q., E-mail: Zhuzhongqi@ynu.edu.cn [Yunnan Key Laboratory of Micro/Nano Materials & Technology, Yunnan University, Kunming 650091 (China); School of Physical Science and Technology, Yunnan University, Kunming 650091 (China); Liu, Q.J., E-mail: qjliu@ynu.edu.cn [Yunnan Key Laboratory of Micro/Nano Materials & Technology, Yunnan University, Kunming 650091 (China)

    2015-10-15

    Highlights: • The (Yb, N)-TiO{sub 2} nanoparticles were prepared and characterized. • The spectrum absorption region of (Yb, N)-TiO{sub 2} is red-shifted to visible light. • The recombination of the photo-generated electron–hole pairs of (Yb, N)-TiO{sub 2} is suppressed. • The photocatalytic activity of (Yb, N)-TiO{sub 2} is more higher than that of TiO{sub 2}-P25, N-TiO{sub 2} and the Yb-TiO{sub 2}. - Abstract: (Yb, N)-TiO{sub 2} photocatalyst has been synthesized by sol–gel method combined with microwave chemical synthesis. Also, the efficiency of the (Yb, N)-TiO{sub 2} as a photocatalyst for the degradation of methylene blue (MB) using visible light irradiation has been evaluated. The prepared samples were characterized by XRD, TEM, XPS, UV–vis-DRS and PL. The results show that the (Yb, N)-TiO{sub 2} photocatalyst has the anatase TiO{sub 2} crystalline phase. The TEM micrograph demonstrated that the average particle size of the sample was about 12 nm. The band-gap energy absorption edge shifted to longer wavelength as compared to commercial TiO{sub 2}-P25, N-TiO{sub 2} and the Yb-TiO{sub 2} prepared by our group. Results of degradation revealed that the (Yb, N)-TiO{sub 2} has shown much more higher photocatalytic activity than that of the TiO{sub 2}-P25, the N-TiO{sub 2} and the Yb-TiO{sub 2} under the visible light.

  16. Layer structured Na{sub 2}Ni(MoO{sub 4}){sub 2} particles as a visible-light-driven photocatalyst for degradation of methylene blue

    Energy Technology Data Exchange (ETDEWEB)

    Lu, Yuting; Chen, Luyang; Huang, Yanlin [College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou 215123 (China); Chen, Cuili; Kim, Sun Il [Department of Physics and Interdisciplinary Program of Biomedical, Mechanical & Electrical Engineering, Pukyong National University, Busan 608-737 (Korea, Republic of); Seo, Hyo Jin, E-mail: hjseo@pknu.ac.kr [Department of Physics and Interdisciplinary Program of Biomedical, Mechanical & Electrical Engineering, Pukyong National University, Busan 608-737 (Korea, Republic of)

    2015-03-15

    Highlights: • Na{sub 2}Ni(MoO{sub 4}){sub 2} nanoparticles were developed by Pechini method. • The nanoparticles show high absorption in UV–vis wavelength region. • Na{sub 2}Ni(MoO{sub 4}){sub 2} has high activity in the MB dye degradation under visible light. • Hexagonal layers with heavily distorted NiO{sub 6} were superiority for photocatalysis. - Abstract: A new visible-light-driven photocatalyst of Na{sub 2}Ni(MoO{sub 4}){sub 2} particle was prepared by the modified Pechini method. The crystal structure was measured by X-ray diffraction (XRD) and the structural refinement. The sample was investigated by scanning electron microscope (SEM), transmission electron microscopy (TEM), and UV–vis absorption spectrum measurements. The average size of Na{sub 2}Ni(MoO{sub 4}){sub 2} particle is about 180 nm. Na{sub 2}Ni(MoO{sub 4}){sub 2} particle have an efficient optical absorption in the UV–visible light wavelength region with a direct allowed electronic transition of 2.06 eV. The effective photodegradation of methylene blue (MB) dye was demonstrated, which benefits from the special crystal structure of Na{sub 2}Ni(MoO{sub 4}){sub 2} particle. This crystal lattice has two infinite chains formed by (Ni,Na)O{sub 6} and MoO{sub 4} polyhedra standing in lines alone with the inner wall of the hexagonal tunnels. This results in the efficient optical absorption and provides more chances for electron–hole separations, which can further react with dye molecules to oxidize the dye pollutant into non-toxic products.

  17. Time resolved XANES illustrates a substrate-mediated redox process in Prussian blue cultural heritage materials

    Science.gov (United States)

    Gervais, Claire; Lanquille, Marie-Angélique; Moretti, Giulia; Réguer, Solenn

    2016-05-01

    The pigment Prussian blue is studied in heritage science because of its capricious fading behavior under light exposure. We show here that XANES can be used to study the photosensitivity of Prussian blue heritage materials despite X-ray radiation damage. We used an original approach based on X-ray photochemistry to investigate in depth the redox process of Prussian blue when it is associated with a cellulosic substrate, as in cyanotypes and watercolors. By modifying cation and proton contents of the paper substrate, we could tune both rate and extent of Prussian blue reduction. These results demonstrate that the photoreduction and fading of Prussian blue is principally mediated by the substrate and its interaction with the oxygen of the environment.

  18. Maintaining ocular safety with light exposure, focusing on devices for optogenetic stimulation.

    Science.gov (United States)

    Yan, Boyuan; Vakulenko, Maksim; Min, Seok-Hong; Hauswirth, William W; Nirenberg, Sheila

    2016-04-01

    Optogenetics methods are rapidly being developed as therapeutic tools for treating neurological diseases, in particular, retinal degenerative diseases. A critical component of the development is testing the safety of the light stimulation used to activate the optogenetic proteins. While the stimulation needs to be sufficient to produce neural responses in the targeted retinal cell class, it also needs to be below photochemical and photothermal limits known to cause ocular damage. The maximal permissible exposure is determined by a variety of factors, including wavelength, exposure duration, visual angle, pupil size, pulse width, pulse pattern, and repetition frequency. In this paper, we develop utilities to systematically and efficiently assess the contributions of these parameters in relation to the limits, following directly from the 2014 American National Standards Institute (ANSI). We also provide an array of stimulus protocols that fall within the bounds of both safety and effectiveness. Additional verification of safety is provided with a case study in rats using one of these protocols. PMID:26882975

  19. Effects of embryonic and adult exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin on hepatic microsomal testosterone hydroxylase activities in great blue herons (Ardea herodias)

    Energy Technology Data Exchange (ETDEWEB)

    Sanderson, J.T.; Giesy, J.P. [Michigan State Univ., East Lansing, MI (United States); Janz, D.M.; Bellward, G.D. [Univ. of British Columbia, Vancouver, British Columbia (Canada)

    1997-06-01

    In a continuing effort to evaluate biomarkers of exposure of great blue herons (Ardea herodias) to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and related halogenated aromatic hydrocarbons, the authors examined the effect of TCDD on hepatic microsomal testosterone hydroxylase activities. Heron embryos were exposed in ovo to 2 {micro}g TCDD/kg egg (or corn oil vehicle) and sacrificed at hatch or 7 d posthatch. Adult herons were exposed intraperitoneally to 20 {micro}g TCDD/kg and sacrificed 2 weeks later. The sex of the birds was known for the adults only. Hepatic microsomes of herons of each age group were able to hydroxylate testosterone at the 2{beta}, 6{beta}, 15{alpha}, 16{alpha}, or 16{beta} positions. In 7-d-old chicks, an additional unidentified compound was formed. The age of the untreated herons had a strong influence on the activities of the five hydroxylases, with changes of up to 17-fold. The TCDD significantly induced 2{beta}-, 6{beta}, and 15{alpha}-testosterone hydroxylase activities in the adult females, 15{alpha} in the adult males, and 6{beta}-testosterone hydroxylase activity in the hatchlings. In the 7-d-old chicks, induction was no longer apparent. A significant correlation existed between hepatic microsomal ethoxyresorufin O-deethylase (EROD) and 6{beta}-testosterone hydroxylase activity in hatchlings and adult female herons. The TCDD-induced changes in testosterone hydroxylase activities occurred at doses that resulted in tissue concentrations and levels of EROD induction that were environmentally relevant, but did not result in overt toxicities.

  20. Drop-out and mood improvement: a randomised controlled trial with light exposure and physical exercise [ISRCTN36478292

    Directory of Open Access Journals (Sweden)

    Lönnqvist Jouko

    2004-08-01

    Full Text Available Abstract Background Combining bright light exposure and physical exercise may be an effective way of relieving depressive symptoms. However, relatively little is known about individual factors predicting either a good response or treatment failure. We explored background variables possibly explaining the individual variation in treatment response or failure in a randomised trial. Methods Participants were volunteers of working-age, free from prior mental disorders and recruited via occupational health centres. The intervention was a randomised 8-week trial with three groups: aerobics in bright light, aerobics in normal room lighting, and relaxation/stretching in bright light. Good response was defined as a 50% decrease in the symptom score on either the Hamilton Depression Rating Scale (HDRS or 8-item scale of atypical symptoms. Background variables for the analysis included sex, age, body-mass index, general health habits, seasonal pattern, and sleep disturbances. Results Complete data were received from 98 subjects (11 men, 87 women. Of them, 42 (5 men, 37 women were classified as responders on the HDRS. Overall, light had a significant effect on the number of responders, as assessed with the HDRS (X2 = .02. The number needed to treat (NNT for light was 3.8. Conclusions We investigated the effect of bright light and exercise on depressive symptoms. Problems with sleep, especially initial insomnia, may predict a good response to treatment using combined light and exercise. Bright light exposure and physical exercise, even in combination, seem to be well tolerated and effective on depressive symptoms.