Literatura académica sobre el tema "Blue LED light"
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Artículos de revistas sobre el tema "Blue LED light"
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Son, Younghyun, Seok-Jun Yang, Chang Jin Kim, Gyeong Sun Lee, Su Mi Choi, Young Guk Yu, Sang-Young Oh, Mi-Sun Jung, A.-Ra Jo y Eun Jung Choi. "Performance Optimization of Blue-light Blocking Lens Through Analysis of Blue Light Emitted from LED Light Sources". Journal of Korean Ophthalmic Optics Society 21, n.º 4 (30 de diciembre de 2016): 393–400. http://dx.doi.org/10.14479/jkoos.2016.21.4.393.
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Johkan, Masahumi, Kazuhiro Shoji, Fumiyuki Goto, Shin-nosuke Hashida y Toshihiro Yoshihara. "Blue Light-emitting Diode Light Irradiation of Seedlings Improves Seedling Quality and Growth after Transplanting in Red Leaf Lettuce". HortScience 45, n.º 12 (diciembre de 2010): 1809–14. http://dx.doi.org/10.21273/hortsci.45.12.1809.
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In this study, we determined the effects of raising seedlings with different light spectra such as with blue, red, and blue + red light-emitting diode (LED) lights on seedling quality and yield of red leaf lettuce plants. The light treatments we used were applied for a period of 1 week and consisted of 100 μmol·m−2·s−1 of blue light, simultaneous irradiation with 50 μmol·m−2·s−1 of blue light and 50 μmol·m−2·s−1 of red light, and 100 μmol·m−2·s−1 of red light. At the end of the light treatment, that is 17 days after sowing (DAS), the leaf area and shoot fresh weight (FW) of the lettuce seedlings treated with red light increased by 33% and 25%, respectively, and the dry weight of the shoots and roots of the lettuce seedlings treated with blue-containing LED lights increased by greater than 29% and greater than 83% compared with seedlings grown under a white fluorescent lamp (FL). The shoot/root ratio and specific leaf area of plants irradiated with blue-containing LED lights decreased. At 45 DAS, higher leaf areas and FWs were obtained in lettuce plants treated with blue-containing LED lights. The total chlorophyll (Chl) contents in lettuce plants treated with blue-containing and red lights were less than that of lettuce plants treated with FL, but the Chl a/b ratio and carotenoid content increased under blue-containing LED lights. Polyphenol contents and the total antioxidant status (TAS) were greater in lettuce seedlings treated with blue-containing LED lights than in those treated with FL at 17 DAS. The higher polyphenol contents and TAS in lettuce seedlings at 17 DAS decreased in lettuce plants at 45 DAS. In conclusion, our results indicate that raising seedlings treated with blue light promoted the growth of lettuce plants after transplanting. This is likely because of high shoot and root biomasses, a high content of photosynthetic pigments, and high antioxidant activities in the lettuce seedlings before transplanting. The compact morphology of lettuce seedlings treated with blue LED light would be also useful for transplanting.
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JANCIN, BRUCE. "Home-Based LED: Blue Light Gets Green Light". Skin & Allergy News 40, n.º 5 (mayo de 2009): 36. http://dx.doi.org/10.1016/s0037-6337(09)70217-7.
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Jung, Conrad H. G., Peter Waldeck, Shadi Sykora, Steffen Braune, Ingolf Petrick, Jan-Heiner Küpper y Friedrich Jung. "Influence of Different Light-Emitting Diode Colors on Growth and Phycobiliprotein Generation of Arthrospira platensis". Life 12, n.º 6 (15 de junio de 2022): 895. http://dx.doi.org/10.3390/life12060895.
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Light-emitting diodes (LED) can be utilized as tailorable artificial light sources for the cultivation of cyanobacteria such as Arthrospira platensis (AP). To study the influence of different LED light colors on phototrophic growth and biomass composition, AP was cultured in closed bioreactors and exposed to red, green, blue, or white LED lights. The illumination with red LED light resulted in the highest cell growth and highest cell densities compared to all other light sources (order of cell densities: red > white > green > blue LED light). In contrast, the highest phycocyanin concentrations were found when AP was cultured under blue LED light (e.g., order of concentrations: blue > white > red > green LED light). LED-blue light stimulated the accumulation of nitrogen compounds in the form of phycobiliproteins at the expense of cell growth. The results of the study revealed that exposure to different LED light colors can improve the quality and quantity of the biomass gained in AP cultures.
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Kim, Jun-Sub y Ssang-Taek Steve Lim. "LED Light-Induced ROS Differentially Regulates Focal Adhesion Kinase Activity in HaCaT Cell Viability". Current Issues in Molecular Biology 44, n.º 3 (4 de marzo de 2022): 1235–46. http://dx.doi.org/10.3390/cimb44030082.
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In this study, changes in cell signaling mechanisms in skin cells induced by various wavelengths and intensities of light-emitting diodes (LED) were investigated, focusing on the activity of focal adhesion kinase (FAK) in particular. We examined the effect of LED irradiation on cell survival, the generation of intracellular reactive oxygen species (ROS), and the activity of various cell-signaling proteins. Red LED light increased cell viability at all intensities, whereas strong green and blue LED light reduced cell viability, and this effect was reversed by NAC or DPI treatment. Red LED light caused an increase in ROS formation according to the increase in the intensity of the LED light, and green and blue LED lights led to sharp increases in ROS formation. In the initial reaction to LEDs, red LED light only increased the phosphorylation of FAK and extracellular-signal regulated protein kinase (ERK), whereas green and blue LED lights increased the phosphorylation of inhibitory-κB Kinase α (IKKα), c-jun N-terminal kinase (JNK), and p38. The phosphorylation of these intracellular proteins was reduced via FAK inhibitor, NAC, and DPI treatments. Even after 24 h of LED irradiation, the activity of FAK and ERK appeared in cells treated with red LED light but did not appear in cells treated with green and blue LED lights. Furthermore, the activity of caspase-3 was confirmed along with cell detachment. Therefore, our results suggest that red LED light induced mitogenic effects via low levels of ROS–FAK–ERK, while green and blue LED lights induced cytotoxic effects via cellular stress and apoptosis signaling resulting from high levels of ROS.
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König, Yanyan, C. Huchzermeyer y Hans Drexler. "Blaulichtgefährdung der Augen durch Lichtemittierende Dioden (LED)?" ASU Arbeitsmedizin Sozialmedizin Umweltmedizin 2020, n.º 02 (31 de enero de 2020): 109–13. http://dx.doi.org/10.17147/asu-2002-8657.
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Blue light from light-emitting diodes (LED): a risk to the eyes? Background: In occupational and domestic environments people are increasingly exposed to artificial light from light-emitting diodes (LEDs). LEDs have peak emission in the blue range. In this review, we summarise the current knowledge of the possible effects of blue light exposure on ocular health. Effects of blue light on the regulation of physiological functions will be considered elsewhere. Methods: We performed a narrative review. We included preclinical data as well as epidemiological studies. We searched MEDLINE, Pubmed, the Cochrane Library and International Standard Randomised Controlled Trial Number (ISRCTN)-Register clinical trial registers from 01 January 2014 to 31 May 2019. Results: The accumulated experimental evidence obtained from different experimental models has indicated that excessive exposure to blue light can induce damage in the retinal pigment epithelium (RPE), in photoreceptors and ganglion cells. Previous epidemiological findings are equivocal regarding any causal links between blue light exposure and the development of macular degeneration (AMD). In vitro and in vivo evidence suggests that blue light exposure may influence the progression of uveal melanoma. Conclusions: Long-term effects of LEDs on ocular health cannot be definitively assessed on the basis of current knowledge. Susceptibility to blue light damage varies among the different species. The severity of light-induced retinal damage changes with the time of the day and depends on the diet and genetic background. Additional studies on the safety of long-term exposure to low levels of blue light are needed to determine the safety of LEDs for ocular health. Keywords: blue light – light-emitting diode – macular degeneration – uveal melanoma
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Jung, Myoung Hoon, Seok-Jun Yang, Ju Sung Yuk, Sang-Young Oh, Chang-Jin Kim, Jungmook Lyu y Eun Jung Choi. "Evaluation of Blue Light Hazards in LED Lightings". Journal of Korean Ophthalmic Optics Society 20, n.º 3 (30 de septiembre de 2015): 293–300. http://dx.doi.org/10.14479/jkoos.2015.20.3.293.
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Brgoch, Jakoah y Shruti Hariyani. "(Invited) Advancing Human-Centric Lighting". ECS Meeting Abstracts MA2022-02, n.º 51 (9 de octubre de 2022): 1958. http://dx.doi.org/10.1149/ma2022-02511958mtgabs.
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The concept of human-centric lighting stems from the evolution of sunlight’s intensity and color temperature throughout the course of a day. This natural progression of bright cold-white light during the middle of the day to a softer warm-white light in the evening stimulates intrinsic photosensitive retinal ganglion cells that control our circadian rhythm. The blue-hue of daylight activates these cells to produce dopamine and cortisol while suppressing melatonin, the sleep hormone, to keep humans awake and alert. The current generation of energy-efficient LED lights reproduce daylight by converting a blue-emitting LED into a broad-spectrum white light using inorganic phosphors. Unfortunately, the resulting intense blue-hue generated by cheap LED bulbs and the underlying blue light from even the most expensive bulbs have been shown to cause macular degeneration, cataract formation, mood disorders, and circadian disruption, resulting in insomnia and fatigue. This talk will investigate the production of a ‘human-centric’ light that minimizes blue light by using a violet LED chip and inorganic phosphors. We report a new phosphor, Na2MgPO4F:Eu2+, which can be readily excited by violet light to produce a bright blue emission. This material possesses all the necessary requirements for LED lighting, including a high quantum yield, thermally robust emission, and impressive chemical stability. Incorporating this material into a prototype device demonstrates our ability produce a warm-white light with a higher color rendering index than a commercially purchased LED light bulb while significantly reducing the blue component.
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Ebbesen, Finn, Hendrik Jan Vreman y Thor Willy Ruud Hansen. "Blue-Green (~480 nm) versus Blue (~460 nm) Light for Newborn Phototherapy—Safety Considerations". International Journal of Molecular Sciences 24, n.º 1 (27 de diciembre de 2022): 461. http://dx.doi.org/10.3390/ijms24010461.
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We have previously shown that the phototherapy of hyperbilirubinemic neonates using blue-green LED light with a peak wavelength of ~478 nm is 31% more efficient for removing unconjugated bilirubin from circulation than blue LED light with a peak wavelength of ~452 nm. Based on these results, we recommended that the phototherapy of hyperbilirubinemic newborns be practiced with light of ~480 nm. Aim: Identify and discuss the most prominent potential changes that have been observed in the health effects of phototherapy using either blue fluorescent- or blue LED light and speculate on the expected effects of changing to blue-green LED light phototherapy. Search the phototherapy literature using the terms neonate, hyperbilirubinemia, and phototherapy in the PubMed and Embase databases. Transitioning from blue fluorescent light to blue-green LED light will expose neonates to less light in the 400–450 nm spectral range, potentially leading to less photo-oxidation and geno-/cytotoxicity, reduced risk of cancer, and decreased mortality in extremely low-birthweight neonates. The riboflavin level may decline, and the increased production and retention of bronze pigments may occur in predisposed neonates due to enhanced lumirubin formation. The production of pre-inflammatory cytokines may rise. Hemodynamic responses and transepidermal water loss are less likely to occur. The risk of hyperthermia may decrease with the use of blue-green LED light and the risk of hypothermia may increase. Parent–neonate attachment and breastfeeding will be positively affected because of the shortened duration of phototherapy. The latter may also lead to a significant reduction in the cost of phototherapy procedures as well as the hospitalization process.
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Le, Anh Tuan, Ju-Kyung Yu, Gyung-Deok Han, Thuong Kiet Do y Yong-Suk Chung. "Potential Use of Colored LED Lights to Increase the Production of Bioactive Metabolites Hedyotis corymbosa (L.) Lam". Plants 11, n.º 2 (15 de enero de 2022): 225. http://dx.doi.org/10.3390/plants11020225.
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Hedyotis corymbosa (L.) Lam is a wild herb that is used in traditional Indian, Chinese, and African medicine. Light-emitting diode (LED) technology is paving the way to enhance crop production and inducing targeted photomorphogenic, biochemical, or physiological responses in plants. This study examines the efficiency of H. corymbosa (L.) Lam production under blue 450 nm and red 660 nm LED lights for overall plant growth, photosynthetic characteristics, and the contents of metabolite compounds. Our research showed that blue LED lights provided a positive effect on enhancing plant growth and overall biomass. In addition, blue LED lights are more effective in controlling the production of sucrose, starch, total phenolic compounds, and total flavonoid compared to red LED lights. However, blue and red LED lights played essential but different roles in photosynthetic characteristics. Our results showed the potential of colored LED light applications in improving farming methods and increasing metabolite production in herbs.
Tesis sobre el tema "Blue LED light"
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TARTAGLIONE, MARIA FIORELLA. "Ergonomic artificial lighting: study of the chronobiological effects of light radiations on human health". Doctoral thesis, Università Politecnica delle Marche, 2021. http://hdl.handle.net/11566/291076.
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La radiazione visibile ha effetti sul ciclo circadiano degli organismi viventi. Questa tesi ha studiato gli effetti cronobiologici della radiazione luminosa in vitro su cheratinociti e in vivo su Drosophila melanogaster.
Sono stati studiati gli effetti di una esposizione di tre giorni a radiazione luminosa blu e rossa emessa da LED rispetto ad un gruppo di controllo tenuto al buio. Su cellule di cheratinociti (HaCaT) sono stati studiati: la vitalità cellulare, l'apoptosi, il ciclo cellulare, l'espressione dei geni circadiani e la proteomica. Su Drosophila melanogaster sono state studiate: la risposta a stress termici e al paraquat, la motilità e l'espressione di alcuni geni clock.
La radiazione luminosa ha diversi effetti biologici sui cheratinociti, in relazione alla lunghezza d'onda, al tempo di esposizione e all'intensità. Un’esposizione di 12h di luce blu ad alta intensità per tre giorni ha ridotto la proliferazione cellulare, aumentato l'apoptosi, modificato il ciclo cellulare, sincronizzato gli orologi circadiani, alterato i livelli proteici della classe ossidoreduttasi, aumentato la concentrazione di ROS intracellulari. Nei moscerini esposti per tre giorni a luce blu, sono stati osservati una diminuzione del tempo di recupero dal coma indotto dal freddo, una diminuzione della sopravvivenza se sottoposti a trattamento con alta temperatura, un aumento della tossicità al paraquat, un’aumento della motilità e una sovraespressione dei geni clock.
Nei nostri modelli la luce blu ha effetti cronobiologici. La luce blu diminuisce la vitalità dei cheratinociti e l’effetto dipende del tempo di esposizione e dall’intensità. I cheratinociti possiedono una regolazione autonoma del ciclo circadiano probabilmente per far fronte a insulti tossici (luce blu) dall'ambiente esterno. Negli insetti è stato possibile osservare una risposta dopo l’esposizione a luce blu; i geni clock risultano overespressi e alcune funzioni ritmiche circadiane sono modificate.Visible radiation affects the circadian cycle of living organisms. This thesis studied the chronobiological effects of light radiation in vitro on keratinocytes and in vivo on Drosophila melanogaster. The effects of a three-day exposure to blue and red light radiation emitted by LEDs on these two models were compared with a control group kept in the dark. On keratinocytes (HaCaT) cell viability, apoptosis, cell cycle, circadian gene expression and proteomics were analysed. On Drosophila melanogaster the response to thermal stress and paraquat, motility and expression of some clock genes were studied. Light radiation has different biological effects on keratinocytes, due to wavelength, exposure time and intensity. Exposure to 12-hour high-intensity blue light for three days reduced cell proliferation, increased apoptosis, modified the cell cycle, synchronized circadian clocks, altered oxidoreductase class protein levels, and increased intracellular ROS concentration. The same exposure in Drosophila melanogaster decreased recovery time from cold-induced coma, decreased survival to high temperature treatment, increased toxicity to paraquat, increased motility, and induced overexpression of clock genes. In our models, blue light has chronobiological effects. Blue light decreases keratinocyte viability in a time- and intensity-dependent manner. Keratinocytes have autonomous regulation of the circadian cycle probably to address toxic insults (blue light) from the external environment. In insects, a response could be observed after exposure to blue light; clock genes are over-expressed and some circadian rhythmic functions are modified.
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Okur, Serdal. "Optical characterization of InGaN heterostructures for blue light emitters and vertical cavity lasers: Efficiency and recombination dynamics". VCU Scholars Compass, 2014. http://scholarscompass.vcu.edu/etd/3647.
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OPTICAL CHARACTERIZATION OF INGAN HETEROSTRUCTURES FOR BLUE LIGHT EMITTERS AND VERTICAL CAVITY LASERS: EFFICIENCY AND RECOMBINATION DYNAMICS
By Serdal Okur, Ph.D.
A thesis submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy at Virginia Commonwealth University.
Virginia Commonwealth University, 2014.
Major Director: Ümit Özgür, Associate Professor, Electrical and Computer Engineering
This thesis explores radiative efficiencies and recombination dynamics in InGaN-based heterostructures and their applications as active regions in blue light emitters and particularly vertical cavities. The investigations focus on understanding the mechanism of efficiency loss at high injection as well as developing designs to mitigate it, exploring nonpolar and semipolar crystal orientations to improve radiative efficiency, integration of optimized active regions with high reflectivity dielectric mirrors in vertical cavity structures, and achieving strong exciton-photon coupling regime in these microcavities for potential polariton lasing. In regard to active regions, multiple double heterostructure (DH) designs with sufficiently thick staircase electron injection (SEI) layers, which act as electron coolers to reduce the overflow of hot electrons injected into the active region, were found to be more viable to achieve high efficiencies and to mitigate the efficiency loss at high injection. Such active regions were embedded in novel vertical cavity structure designs with full dielectric distributed Bragg reflectors (DBRs) through epitaxial lateral overgrowth (ELO), eliminating the problems associated with semiconductor bottom DBRs having narrow stopbands and the cumbersome substrate removal process. Moreover, the ELO technique
allowed the injection of carriers only through the high quality regions with substantially reduced threading dislocation densities compared to regular GaN templates grown on sapphire.
Reduced electron-hole wavefunction overlap in polar heterostructures was shown to hamper the efficiency of particularly thick active regions (thicker than 3 nm) possessing three-dimensional density of states needed for higher optical output. In addition, excitation density-dependent photoluminescence (PL) measurements showed superior optical quality of double heterostructure (3 nm InGaN wells) active regions compared to quantum wells (2 nm InGaN wells) suggesting a minimum limit for the active region thickness. Therefore, multiple relatively thin but still three dimensional InGaN active regions separated by thin and low barriers were found to be more efficient for InGaN light emitters. Investigations of electroluminescence from light emitting diodes (LEDs) incorporating multi DH InGaN active regions (e.g. quad 3 nm DH) and thick SEIs (two 20 nm-thick InGaN layers with step increase in In content) revealed higher emission intensities compared to LEDs with thinner or no SEI. This indicated that injected electrons were cooled sufficiently with thicker SEI layers and their overflow was greatly reduced resulting in efficient recombination in the active region. Among the structures considered to enhance the quantum efficiency, the multi-DH design with a sufficiently thick SEI layer constitutes a viable approach to achieve high efficiency also in blue lasers.
Owing to its high exciton binding energy, GaN is one of the ideal candidates for microcavities exploiting the strong exciton-photon coupling to realize the mixed quasiparticles called polaritons and achieve ideally thresholdless polariton lasing at room temperature. Angle-resolved PL and cathodoluminescence measurements revealed large Rabi splitting values up to 75 meV indicative of the strong exciton-photon coupling regime in InGaN-based microcavities with bottom semiconductor AlN/GaN and a top dielectric SiO2/SiNxDBRs, which exhibited quality
factors as high as 1300. Vertical cavity structures with all dielectric DBRs were also achieved by employing a novel ELO method that allowed integration of a high quality InGaN cavity active region with a dielectric bottom DBR without removal of the substrate while forming a current aperture through the ideally defect-free active region. The full-cavity structures formed as such were shown to exhibit clear cavity modes near 400 and 412 nm in the reflectivity spectrum and quality factors of 500.
Although the polar c-plane orientation has been the main platform for the development of nitride optoelectronics, significant improvement of the electron and hole wavefunction overlap in nonpolar and semipolar InGaN heterostructures makes them highly promising candidates for light emitting devices provided that they can be produced with good crystal quality. To evaluate their true potential and shed light on the limitations put forth by the structural defects, optical processes in several nonpolar and semipolar orientations of GaN and InGaN heterostructures were investigated. Particularly, stacking faults were found to affect significantly the optical properties, substantially influencing the carrier dynamics in nonpolar (1-100), and semipolar (1-101) and (11-22)GaN layers. Carrier trapping/detrapping by stacking faults and carrier transfer between stacking faults and donors were revealed by monitoring the carrier recombination dynamics at different temperatures, while nonradiative recombination was the dominant process at room temperature. Although it is evident that nonpolar (1-100)GaN and semipolar (11-22)GaN require further improvement of material quality, steady-state and time-resolved PL measurements support that (1-101)-oriented GaN templates and InGaN active regions exhibit optical performance comparable to their highly optimized polar c-plane counterparts, and therefore, are promising for vertical cavities and light emitting device applications.
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Kestler, Jessica. "How Does Pre-Sleep Usage of LED Screen Technology Affect Sleeping Behavior and Academic Achievement?" University of Cincinnati / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1511799309504311.
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Štěpánek, Jaroslav. "Fotobiologická bezpečnost světelných zdrojů a osvětlovacích soustav". Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2014. http://www.nusl.cz/ntk/nusl-220697.
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The thesis deals with the problems of the photobiological lamp and lamps systems safety. It is divided into theoretical and practical parts. The theoretical part touches the basic knowledge concerning the eye and vision, eye and skin diseases caused by excessive exposure to non-ionizing radiation. And besides that there are described the sources of light causing the possible exposure and further more it includes the methodology of measurement and evaluation of photobiological safety. The practical part investigates a measurement of the spectrum of light sources. The measured data are evaluated according to the methods mentioned in the theoretical part.
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Oliveira, Clélia Aparecida da Silva 1972. "Tratamento de corante têxtil por eletrólise, fotólise e fotocatálise utilizando LED UV = Treatment of textile dye by electrolytic, photolytic and photocatalytic processes". [s.n.], 2013. http://repositorio.unicamp.br/jspui/handle/REPOSIP/267750.
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Orientador: Peterson Bueno de MoraesDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Tecnologia
Made available in DSpace on 2018-08-23T06:55:03Z (GMT). No. of bitstreams: 1 Oliveira_CleliaAparecidadaSilva_M.pdf: 1434373 bytes, checksum: 2411a1ce9b13fbe4e8f7d778c6dfd3ea (MD5) Previous issue date: 2013
Resumo: A indústria têxtil gera elevados volumes de efluentes com alta carga orgânica e compostos recalcitrantes, os quais são tratados por sistemas baseados em processos físicos, químicos e biológicos convencionais. Entretanto, o caráter não destrutivo dos tratamentos convencionais representa um sério problema no setor. Nos últimos 20 anos, os Processos Oxidativos Avançados (POA) têm estado em evidência devido à sua capacidade em degradar inúmeros compostos orgânicos contidos em águas e efluentes. Uma grande quantidade de trabalhos utilizando luz UV a partir de lâmpadas de vapor de mercúrio tem resultado em elevada eficiência de degradação de substratos recalcitrantes incluindo efluentes têxteis; entretanto, demandam elevado consumo de energia elétrica, encarecendo o tratamento. Em contrapartida, o surgimento de Diodos Emissores de Luz Ultravioleta (LED UV) abre novas fronteiras de aplicação no campo de tratamento de águas residuárias, quanto a custo, operacionalidade e tamanho dos sistemas. Nesse trabalho estudou-se a degradação de um efluente têxtil simulado contendo o corante Remazol Azul Brilhante (C.I. Reactive Blue 19) através de processos eletroquímicos e fotoeletroquímicos que utilizam LED UV, utilizando-se dois reatores: um operando em batelada contendo o fotocatalisador TiO2 e o outro, em fluxo, contendo um cátodo (tela cilíndrica de aço-inoxidável), um tubo de quartzo contendo os LED UV e o Anodo Dimensionalmente Estável (ADE 70%TiO2/30%RuO2). Os resultados demonstraram que, no reator de bancada, a eficiência de remoção de cor foi de 100% para concentração inicial de 50 mg L-1 do corante, em 24 horas de tratamento. No reator em fluxo, utilizando Na2SO4 como eletrólito, o processo eletrolítico resultou em eficiência de 65%; o fotoeletrocatalítico, em 68%, operando a 750 L h-1 e em 57,3 mA cm-2. Quando foi utilizado o eletrólito NaCl, obteve-se remoção de 100% da cor em 5 minutos de tratamento a 750 L h-1, independente da concentração inicial do corante utilizada (50 mg L-1 ou 100 mg L-1), da concentração do eletrólito (0,05 M ou 0,1 M), da densidade de corrente (14,3 mA cm-2 , 28,7 mA cm-2 ou 57,3 mA cm-2) e do processo utilizado
Abstract: The textile industry generates large amount of wastewater containing significant organic load and recalcitrant compounds, which in most cases are treated by conventional systems involving physical, chemical and biological processes, the latter represented mainly by activated-sludge treatment. However, the non-destructive profile of conventional treatments is a serious problem for textile-based industry. Over the past 20 years, the study of Advanced Oxidation Processes (AOP) has been carried out due to its high capacity degradation of numerous organic pollutants contained in waters and wastewaters. Research using UV light from mercury vapor lamps usually has resulted in high efficiency degradation of recalcitrant substrates including textile effluents but requires high electrical power consumption besides other drawbacks. In contrast, the emergence of Ultraviolet Light Emitting Diodes (UV LED) opens new perspectives for application on wastewater treatment, concerning efficiency, footprint and costs of the systems. In this work we studied the degradation of a simulated wastewater containing a textile dye, Remazol Brilliant Blue (C.I. Reactive Blue 19) through electrochemical and photoelectrochemical processes using UV LED as ultraviolet radiation source. The experimental apparatus consisted of two systems: the first, a bench-scale reactor containing TiO2 photocatalyst (P25 DEGUSSA) in solution, and another pilot-scale system operated in batch recirculation mode composed of an tubular stainless-steel screen cathode, a quartz tube containing the UV LED and a oxide-coated titanium anode (DSA©30%TiO2/70%RuO2). The results showed total decolorization of a solution containing 50 mg L-1 of RB in 24-hour treatment in the bench-scale reactor. Tests on flow reactor using Na2SO4 as supporting electrolyte resulted in 65% of color removal using electrolytic process and 68% for photoelectrocatalytic process operating at 750 L h-1 and 57.3 mA cm-2. In experiments using the electrolyte NaCl it was obtained 100% in the color degradation within 5 minutes of treatment at 750 L h-1, regardless of the: initial concentration of dye used (50 mg L-1; 100 mg L-1), concentration of the electrolyte (0.05 M; 0.1 M) and current density value (14.3; 28.7; 57.3 mA cm-2)
Mestrado
Tecnologia e Inovação
Mestra em Tecnologia
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Liang, Hu. "Fabrication and characteristics of the InGaN/GaN multiple quantum well blue LEDs /". View Abstract or Full-Text, 2003. http://library.ust.hk/cgi/db/thesis.pl?ELEC%202003%20LIANG.
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Thesis (M. Phil.)--Hong Kong University of Science and Technology, 2003.Includes bibliographical references (leaves 62-66). Also available in electronic version. Access restricted to campus users.
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Liang, Hu. "Fabrication of high power InGaN/GaN multiple quantum well blue LEDs grown on patterned Si substrates /". View abstract or full-text, 2008. http://library.ust.hk/cgi/db/thesis.pl?ECED%202008%20LIANG.
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Leclercq, Bastien. "Rôle de la rétine dans les fonctions non-visuelles : traitement des informations relatives à la photopériode et impact de la lumière bleue sur le comportement". Thesis, Strasbourg, 2021. http://www.theses.fr/2021STRAJ099.
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Les cellules ganglionnaires intrinsèquement photosensibles (ipRGCs) constituent une interface majeure dans la régulation de la physiologie et des comportements par la lumière. Ces travaux démontrent que la présence de ces cellules dans la rétine est suffisante pour permettre à des souris d’intégrer les variations saisonnières de la photopériode. De plus, nous décrivons des modifications dépendantes de la photopériode au sein des ipRGCs. Ces résultats suggèrent que la rétine pourrait intégrer les variations de la photopériode, afin d’assurer au mieux les fonctions visuelles et non-visuelles à travers les saisons. Par ailleurs, ces travaux ont exploré les effets de la surexposition aux écrans et notamment à un enrichissement en lumière bleue sur le comportement de type anxieux/agressif. Les ipRGCs, sensibles à la lumière bleue (460-480nm), sont connectées avec de nombreuses structures cérébrales impliquées dans la régulation des comportements. Nos résultats montrent qu’une exposition prolongée à un environnement enrichi en lumière bleue peut modifier les comportements de type agressifThe intrinsically photosensitive retinal ganglion cells (ipRGCs) constitute a key interface in the regulation of our physiology and behaviours by light. First, this thesis demonstrates that the ipRGCs are sufficient to ensure a normal photoperiod integration. Mice without rods nor cones still encode photoperiod variation through melatonin secretion and display photoperiod-dependent locomotor activity changes. This is the first time we describe photoperiod-dependent changes of the ipRGCs. These data suggest that the retina itself could integrate the photoperiod locally, and thus constitute an adaptative mechanism to regulate both visual and non-visual functions depending on the seasons. Secondly, this thesis assessed the effects of screen overexposure and notably to blue light enrichment on aggressive/anxious behaviour. ipRGCs are particularly sensitive to blue light (460-480nm) and are connected to various brain structures involved in behaviour regulation. We show that exposure to a blue light-enriched environment can modify behaviour such as aggressiveness
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Shakirullah, Mohammad. "Oxygenation et degradation du polymere, decoloration du sensibilisateur lors de la photooxygenation du polybutadiene-1,4 cis sensibilisee par les colorants". Université Louis Pasteur (Strasbourg) (1971-2008), 1987. http://www.theses.fr/1987STR13081.
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Sous l'influence conjuguee de la lumiere et de l'oxygene, une solution de polymere et de bleu de methylene subit plusieurs transformations. La photooxygenation conduit uniquement a des hydroperoxydes allergiques: interaction entre l'etat triplet du bleu de methylene et les groupes hydroperoxydes portes par les chaines macromoleculaires. Cinetique et mecanisme
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Noordhuis-Fairfax, Sarina. "Field | Guide: John Berger and the diagrammatic exploration of place". Phd thesis, Canberra, ACT : The Australian National University, 2018. http://hdl.handle.net/1885/154278.
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Positioned between writing and drawing, the diagram is proposed by John Berger as an alternative strategy for articulating encounters with landscape. A diagrammatic approach offers a schematic vocabulary that can compress time and offer a spatial reading of information. Situated within the contemporary field of direct data visualisation, my practice-led research interprets Berger’s ‘Field’ essay as a guide to producing four field | studies within a suburban park in Canberra. My seasonal investigations demonstrate how applying the conventions of the pictorial list, dot-distribution map, routing diagram and colour-wheel reveals subtle ecological and biographical narratives.
Libros sobre el tema "Blue LED light"
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Mighty Bright Hammerhead Led Light Blue. Mighty Bright, 2011.
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Mighty Bright Blue Xtraflex LED Book Light. Mighty Bright, 2010.
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Me, Better Better. Mandala Yoga Mantra Goodvibes: Sacred Fractal Psychedelic Blue Led Light Geometric Circle Art. Independently Published, 2020.
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Mandala Yoga Mantra Goodvibes: Sacred Fractal Psychedelic Blue Led Light Geometric Circle Art. Independently Published, 2020.
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KJV Study Bible for Boys Blue/Light Blue Duravella. Baker Books, 2012.
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KJV Study Bible for Boys Blue/Light Blue Duravella. Baker Books, 2016.
Buscar texto completoCapítulos de libros sobre el tema "Blue LED light"
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Yin, Guangjun y Yuanqing Wang. "A New Directional Backlight Using Blue Light LED Design for Autostereoscopic 3D Displays". En Advances in 3D Image and Graphics Representation, Analysis, Computing and Information Technology, 445–53. Singapore: Springer Singapore, 2020. http://dx.doi.org/10.1007/978-981-15-3863-6_49.
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Zhang, Yunhong, Yingbao Yang, Yilin Chen, Yong Yang y Yu Chao. "Evaluate Fatigue of Blue Light Influence on General LCD, Low Blue Light LCD and OLED Displays". En Advances in Neuroergonomics and Cognitive Engineering, 166–74. Cham: Springer International Publishing, 2017. http://dx.doi.org/10.1007/978-3-319-60642-2_15.
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Kim, Taegon, Yongpil Park, Yangsun Lee y Minwoo Cheon. "Effect of Light Therapy of Blue LEDs Irradiation on Sprague Dawley Rat". En Lecture Notes in Electrical Engineering, 181–88. Dordrecht: Springer Netherlands, 2011. http://dx.doi.org/10.1007/978-94-007-2598-0_20.
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Baillot, Raphael y Yannick Deshayes. "Failure Analysis Methodology of Blue LEDs". En Reliability Investigation of LED Devices for Public Light Applications, 107–45. Elsevier, 2017. http://dx.doi.org/10.1016/b978-1-78548-149-9.50003-1.
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Ali, Amjad, Qian Li, Hongyan Fu y Syed Raza Mehdi. "Blue Laser Diode-Based Visible Light Communication and Solid-State Lighting". En Antenna Systems [Working Title]. IntechOpen, 2021. http://dx.doi.org/10.5772/intechopen.100106.
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In this chapter, we review our recent work on blue laser diode-based visible light communication and solid-state lighting. Gallium nitride (GaN) phosphor-converted white light-emitting diodes (Pc-WLEDs) are emerging as an indispensable solid-state lighting (SSL) source for next-generation display system and the lighting industry. Together with the function of lighting, visible light communication (VLC) using Pc-WLEDs has gained increasing attention to fulfill the growing demand for wireless data communication. Practically, the low modulation response and low emitting intensity of light-emitting diodes (LED) are the drawbacks for the development of ultrahigh-speed VLC and high-quality SSL system. Blue GaN laser diode (LD) and remote phosphor-based white light can be used for both high-speed VLC and SSL simultaneously. We demonstrated a color-rendering index (CRI) of 93.8, a correlated color temperature (CCT) of 4435 K, and a data rate of 1.6 Gbps under NRZ-OOK modulation by an exciting blue laser diode on narrowband green−/red-emitting composite phosphor film. This work opens up exciting possibilities for future high-speed indoor VLC and high-quality SSL.
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Weintraub, David A. "Misty Mars". En Life on Mars, 55–69. Princeton University Press, 2020. http://dx.doi.org/10.23943/princeton/9780691209258.003.0005.
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This chapter considers the invented craft of spectroscopy as one of the important research techniques used by mid-nineteenth-century astronomers to the study of Mars. It details how the tools of spectroscopy led to the discovery of proof for the presence of water on the surface and in the atmosphere of Mars. It also discusses that the knowledge that water exists on Mars made astronomers believe they had proof that Mars had an Earth-like climate and that the red patches on Mars were vegetation. The chapter explains that spectroscopy involves channeling a beam of light from any source through a prism or a grating, which spreads the light out into its constituent colors, allowing scientists to study the details of brightness and faintness of the different colors. It mentions William Huggins and William Allen Miller, who suggested that the Mars's red color is a consequence of its inability to reflect violet and blue light.
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Thirumalai, Jagannathan. "Introductory Chapter: The Impression of Light-Emitting Diodes in Space-Age Advancements and Its Effect of Blue LED Irradiation". En Light-Emitting Diode - An Outlook On the Empirical Features and Its Recent Technological Advancements. InTech, 2018. http://dx.doi.org/10.5772/intechopen.79375.
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Kılıç, Bülent. "An Organizational Trauma Intervention". En Impact of Organizational Trauma on Workplace Behavior and Performance, 264–77. IGI Global, 2017. http://dx.doi.org/10.4018/978-1-5225-2021-4.ch011.
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The aim of this chapter is to describe a trauma experienced among blue collar employees at the XYZ car factory in Turkey. Demonstrations led to a halt of production after the representative union signed higher salary at another factory. After the consensus among the parties the production was restarted. However, the trauma and its symptoms emerged. Conflicts and polarization rose among the workers and the employer decided to conduct an intervention program. This study focuses on the pre-intervention, pilot intervention and main intervention programs. Descriptive quotations related to the trauma and the implications of the intervention program are discussed in the light of a theoretical framework. In the present paper, a brief background of the automotive industry and labor unions will be presented. The theoretical perspective is put forward, the implemented program is described, and the descriptive findings are presented then the findings and implications are discussed.
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Chebwogen, Judith y Christopher Mkirema Maghanga. "Fabrication and Characterization of Cobalt-Pigmented Anodized Zinc for Photocatalytic Application". En Thin Films. IntechOpen, 2021. http://dx.doi.org/10.5772/intechopen.93790.
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Population growth and urbanization have led to water scarcity and pollution, which is a health hazard not only to humans but also to the ecosystem in general. This has necessitated coming up with ways of treating water before consumption. Photocatalysis has proved to be one of the most promising cheap techniques that involve chemical utilization of solar energy. TiO2 widely used in photocatalysis absorbs a narrow range of the solar spectrum compared to ZnO. In this regard, this study aimed at preparing and optimizing cobalt-pigmented ZnO, which is applicable in photocatalytic water treatment. The objectives in this study were to fabricate zinc oxide (ZnO) thin films by anodization, pigment the fabricated films with varying cobalt concentrations, characterize the fabricated films optically, and investigate the cobalt-pigmented ZnO’s performance in the methylene blue degradation under UV light irradiation. Mirror-polished zinc plates were sonicated in ethanol and rinsed. Anodization was done at room temperature in 0.5 M oxalic acid at a constant voltage of 10 V for 60 min, and cobalt electrodeposited in the films. Post-deposition treatment was done at 250°C. Optical properties of the films were studied using a UV-VIS- NIR spectrophotometer in the solar range of 300–2500 nm. The photocatalytic activity of the fabricated films was studied in methylene blue solution degradation in the presence of UV light irradiation for 5 h. Cobalt pigmenting was observed to reduce reflectance and optical band gap from 3.34 to 3.10 eV indicating good photocatalytic properties. In this study, ZnO film pigmented with cobalt for 20 s was found to be the most photocatalytic with a rate constant of 0.0317 h−1 and hence had the optimum cobalt concentration for photocatalytic water treatment. This can be applied in small-scale water purification.
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Sivagami, Arasu, Michael Angelo Kandavalli y Bhaskarrao Yakkala. "Design and Evaluation of an Automated Monitoring and Control System for Greenhouse Crop Production". En Next-Generation Greenhouses for Food Security. IntechOpen, 2021. http://dx.doi.org/10.5772/intechopen.97316.
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An embedded system integrated with sensors based on nanomaterial is proposed for closely monitoring and control microclimate parameters 24 hours a day to maximise production over the whole crop growth season by introducing greenhouse for the cultivation of plants or specific plant species. The system will also eliminate errors in human intervention to optimise production of crops. This system consists of sensors and actuators, an Analogue to Digital Converter (ADC) and a Raspberry Pi. The system will determine whether a defined threshold is passed by any climate parameter and systematically changes via the controller. The current work reduces human input through automated irrigation to optimally utilize a scarce resource, namely water. Climatic parameters for plant growth such as, moisture, humidity, temperature, water pressure in drip pipe, soil salinity etc. are monitored and optimized. Furthermore, work was extended to include GSM to control the entire farm remotely. For its success, it is very important to choose a greenhouse location. For instance, the problems are quite different when choosing an adjoining greenhouse, for instance a sunroom or greenhouse. The greenhouse location should be chosen for sunlight, proximity to power and water sources, wind, drain and freeze pockets, and the proximity of the garden and house. The intention behind accomplishment and devise of GSM based Fertigation System is to construct and evaluate the requirement of water in the yield as farming is the major resource of production which habitually depends on the water accessibility. Irrigation of water is usually done by manual method. To ease the work of the farmer GSM based automatic Fertigation (includes chemigation too) system can be implemented so that water wastage can be reduced and also the fertilizer can be added accordingly. Also the Soil Salinity can be checked and reduced if exceeds certain limit. By using GSM, only GSM command via GSM mobile can control the start and stop action of a motor that feeds the field with the water. GSM is used for controlling the entire process and the entire system backbone. It can be used from any distance to control irrigation. The results are assessed by electronic simulator PROTEUS using the desired optimised parameters, the design of this automated greenhouse system with PIC controller. As the inputs to the microcontroller and as an LCD screen record the respective outputs, the model produces a soil moisture sensor, light sensor and temperature sensor. The system performance is accurate and repeatable for measuring and controlling the four parameters that are crucial for plant growth - temperature, humidity, soil moisture and light intensity. With the reduction in electricity consumption, maintenance and complexity, and a flexible and precise environment control form for agriculture, the new system successfully cured quite a couple of defects in existing systems. Nano composite film sensors (Graphene and Graphene mixed in order to optimise the input of fertilisers for chemical composition determination. Using nano technology in agriculture enforces the firm bond between the engineer and farmer. Nano material film-based gas sensors were used to measure the presence of oxygen and CO2.using graphene nano composite sensors integrated into an embedded system, to detect the presence and levels of gases. Improve crop growth with combined red and blue light for lighting under the leavened and solar-powered LED lighting modules. This was achieved by graph/solar cells. The light was measured at the photosynthesis flux (PPFD) of 165 μmol m-2 s-1 by 10 cm of its LED module. LED lights were provided between 4:00 a.m. and 4:00 p.m. in the daytime treatments and night treatments from 10 to 10 hours. The use of the nighttime interlumination of LEDs was also economical than the interlumination of charts. Thus, nightlighting LEDs can effectively improve plant growth and output with less energy than the summer and winter times. Solar panels are best functioning during times of strong sunlight today, but begin to wan when they become too hot and cloudy. By allowing Solar Panels to produce electricity during harsh weather conditions and increase efficiency, a breakthrough in graphene-based solar panels can change everything. Ultimately with a fully autonomous system, agricultural productivity and efficiency, the length of the growing season, energy consumption and water consumption were recorded and monitored by exporting the data over GSM environment. With the steady decrease in the cost of high-performing hardware and software, the increased acceptance of self-employed farming systems, and the emerging agricultural system industry, the results will be reliable control systems covering various aspects of quality and production quantity.
Actas de conferencias sobre el tema "Blue LED light"
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Liang, Ping, Yibo Zheng y Qiang Liu. "High-power blue LED light source system". En International Conference on Optical Instrumentation and Technology, editado por Yongtian Wang, Yunlong Sheng y Kimio Tatsuno. SPIE, 2009. http://dx.doi.org/10.1117/12.837725.
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LU, BONNIE, AMANDA LU y JICUN LU. "Blue Light Free LED Chip and Bulb". En EEET 2021: 2021 4th International Conference on Electronics and Electrical Engineering Technology. New York, NY, USA: ACM, 2021. http://dx.doi.org/10.1145/3508297.3508328.
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Stepanek, Jaroslav, Jan Skoda, Michal Krbal, Martin Motycka y Jan Nekvapil. "Changes of blue light hazard for RGB LED". En 2018 19th International Scientific Conference on Electric Power Engineering (EPE). IEEE, 2018. http://dx.doi.org/10.1109/epe.2018.8395957.
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Weatherley, Thomas, Wei Liu, Camille Haller, Yao Chen, Duncan T. L. Alexander, Jean-François Carlin, Raphaël Butté y Nicolas Grandjean. "Point defects and blue LED efficiency: the critical role of indium". En Light-Emitting Devices, Materials, and Applications XXV, editado por Martin Strassburg, Jong Kyu Kim y Michael R. Krames. SPIE, 2021. http://dx.doi.org/10.1117/12.2576683.
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Kukimoto, Hiroshi. "Overview - Blue-Green Semiconductor LED/Laser Work in Japan". En Compact Blue-Green Lasers. Washington, D.C.: Optica Publishing Group, 1992. http://dx.doi.org/10.1364/cbgl.1992.thc2.
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The research in Japan on the wide-bandgap materials for short-wavelength light emitting devices based on modem growth techniques of MOVPE and MBE started in early 1980s. The first attempt to organize a cooperative research system for wide-gap semiconductors in Japan can be traced back to the year 1984, when about 20 university research groups which had already been engaged in research on wide-gap II-VI materials gathered and started to make plans for joint research. This was followed by a three-year period research project on the property control of compound semiconductors, especially of II-VI, wide-gap III-V and I-III-VI2 materials, within a priority area research program for "New Functionality Materials - Design, Preparation and Control", which started in 1987 under support of the Ministry of Education, Science and Culture. It was renewed in 1990 as an advanced project for additional three years, and since then it has been running with emphasis on atomic-scale control of crystal growth, control of localized electronic states, creation of new optical functionality, quantum structures and new properties, and control of material properties for new optical devices. Under the project, the growth of wide-gap II-VIs, especially of ZnSe and related alloys and superlattices has been very actively studied in many university laboratories.
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Lee, K. H. y S. W. Ricky Lee. "Screen-Printing of Yellow Phosphor Powder on Blue Light Emitting Diode (LED) Arrays for White Light Illumination". En ASME 2007 InterPACK Conference collocated with the ASME/JSME 2007 Thermal Engineering Heat Transfer Summer Conference. ASMEDC, 2007. http://dx.doi.org/10.1115/ipack2007-33971.
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In current technology, white light generation from a light emitting diode (LED) can be achieved by combining the lights from three fundamental colors, namely, red, green and blue (RGB), of LEDs or by coating a phosphor layer onto the surface of a LED chip. The first method involving the RGB color mixing technique requires a complicated electrical circuit design for the control of light intensity and uniformity on the three different colors of LEDs and hence increases the costs of manufacturing. The second method is implemented by coating a layer of yellow phosphor on a blue LED chip for white light illumination. The quality of generated white light heavily depends on the packing density, the thickness and the uniformity of the phosphor coating. There have been some coating methods available in the industry. Each one of them has its own pros-n-cons. In the present study, a new yellow phosphor coating method by screen-printing on blue LED arrays is developed. Compared with conventional coating methods, this screen-printing method is considered relatively simple and rather effective. The newly developed method and the results of prototyping are introduced in this paper in detail.
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Ross, Jennifer, Nathan Newman y Mike Rubin. "GaN for short-wavelength light emitting devices: growth kinetics and techniques". En Compact Blue-Green Lasers. Washington, D.C.: Optica Publishing Group, 1993. http://dx.doi.org/10.1364/cbgl.1993.cthc.3.
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In the recent year, great steps have been achieved in the development of blue-green semiconductor diode lasers and LEDs, however material issues in the wide-bandgap semiconductors still limit practical device applications. The II-VI compounds ZnSe and ZnS and the III-V semiconductors GaN and AIN are the two material system being investigated for green to ultra- violet light emitting devices, with most research to date concentrating on the II-VI materials. Problems with electromigration, heating, and subsequent processing in early ZnSe/ZnS laser diodes has led many researchers to investigate the more robust material GaN for commercially viable short wavelength LEDs and laser diodes. GaN blue LEDs at room temperature have been demonstrated by Akasaki et al. [1], but p-type doping levels are not yet sufficiently high for laser diodes. The main obstacle in fabricating high quality GaN for device applications has been controlling background impurity and dopant concentrations during crystal growth and finding suitable substrates with closely matching lattice and thermal expansion coefficients. The dilemma in obtaining p-type conduction in GaN is hypothesized to be due to a large concentration of nitrogen vacancies[2] acting as shallow donors making compensation difficult. Aside from Akasaki's and Nakamura's work in Japan [1,13], all GaN material by any growth techniques has been n-type. Advances in the last few years, have produced undoped material with a reduced concentration using Metal Organic Chemical Vapor Deposition (MOCVD) (4x1016 cm-3) [3] and plasma/ion-assisted Molecular Beam Epitaxy (MBE) (8 x 1013 cm-3)[4].
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Grandjean, Nicolas. "Burying surface defects in InGaN underlayer to increase blue LED efficiency (Conference Presentation)". En Light-Emitting Devices, Materials, and Applications, editado por Martin Strassburg, Jong Kyu Kim y Michael R. Krames. SPIE, 2019. http://dx.doi.org/10.1117/12.2508320.
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Schneider, Marc, Benjamin Leyrer, Bernhard Osswald, Christian Herbold, Franziska Herrmann, Kirsten Eilert, Jurgen B. Brandner, Jin-Kai Chang, Yi-Chung Huang y Wood-Hi Cheng. "Blue and white light emitting high power density LED modules". En 2015 IEEE 65th Electronic Components and Technology Conference (ECTC). IEEE, 2015. http://dx.doi.org/10.1109/ectc.2015.7159763.
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Hong Jeong Yu, Wonkeun Chung y Sung Hyun Kim. "White light emission from blue InGaN LED with hybrid phosphor". En 2010 IEEE 10th Conference on Nanotechnology (IEEE-NANO). IEEE, 2010. http://dx.doi.org/10.1109/nano.2010.5697998.
Texto completoInformes sobre el tema "Blue LED light"
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Splitter, Gary y Menachem Banai. Microarray Analysis of Brucella melitensis Pathogenesis. United States Department of Agriculture, 2006. http://dx.doi.org/10.32747/2006.7709884.bard.
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Original Objectives 1. To determine the Brucella genes that lead to chronic macrophage infection. 2. To identify Brucella genes that contribute to infection. 3. To confirm the importance of Brucella genes in macrophages and placental cells by mutational analysis. Background Brucella spp. is a Gram-negative facultative intracellular bacterium that infects ruminants causing abortion or birth of severely debilitated animals. Brucellosis continues in Israel, caused by B. melitensis despite an intensive eradication campaign. Problems with the Rev1 vaccine emphasize the need for a greater understanding of Brucella pathogenesis that could improve vaccine designs. Virulent Brucella has developed a successful strategy for survival in its host and transmission to other hosts. To invade the host, virulent Brucella establishes an intracellular niche within macrophages avoiding macrophage killing, ensuring its long-term survival. Then, to exit the host, Brucella uses placenta where it replicates to high numbers resulting in abortion. Also, Brucella traffics to the mammary gland where it is secreted in milk. Missing from our understanding of brucellosis is the surprisingly lillie basic information detailing the mechanisms that permit bacterial persistence in infected macrophages (chronic infection) and dissemination to other animals from infected placental cells and milk (acute infection). Microarray analysis is a powerful approach to determine global gene expression in bacteria. The close genomic similarities of Brucella species and our recent comparative genomic studies of Brucella species using our B. melitensis microarray, suqqests that the data obtained from studying B. melitensis 16M would enable understanding the pathogenicity of other Brucella organisms, particularly the diverse B. melitensis variants that confound Brucella eradication in Israel. Conclusions Results from our BARD studies have identified previously unknown mechanisms of Brucella melitensis pathogenesis- i.e., response to blue light, quorum sensing, second messenger signaling by cyclic di-GMP, the importance of genomic island 2 for lipopolysaccharide in the outer bacterial membrane, and the role of a TIR domain containing protein that mimics a host intracellular signaling molecule. Each one of these pathogenic mechanisms offers major steps in our understanding of Brucella pathogenesis. Strikingly, our molecular results have correlated well to the pathognomonic profile of the disease. We have shown that infected cattle do not elicit antibodies to the organisms at the onset of infection, in correlation to the stealth pathogenesis shown by a molecular approach. Moreover, our field studies have shown that Brucella exploit this time frame to transmit in nature by synchronizing their life cycle to the gestation cycle of their host succumbing to abortion in the last trimester of pregnancy that spreads massive numbers of organisms in the environment. Knowing the bacterial mechanisms that contribute to the virulence of Brucella in its host has initiated the agricultural opportunities for developing new vaccines and diagnostic assays as well as improving control and eradication campaigns based on herd management and linking diagnosis to the pregnancy status of the animals. Scientific and Agricultural Implications Our BARD funded studies have revealed important Brucella virulence mechanisms of pathogenesis. Our publication in Science has identified a highly novel concept where Brucella utilizes blue light to increase its virulence similar to some plant bacterial pathogens. Further, our studies have revealed bacterial second messengers that regulate virulence, quorum sensing mechanisms permitting bacteria to evaluate their environment, and a genomic island that controls synthesis of its lipopolysaccharide surface. Discussions are ongoing with a vaccine company for application of this genomic island knowledge in a Brucella vaccine by the U.S. lab. Also, our new technology of bioengineering bioluminescent Brucella has resulted in a spin-off application for diagnosis of Brucella infected animals by the Israeli lab by prioritizing bacterial diagnosis over serological diagnosis.