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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.
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Huang, Yu-Chia y 黃昱嘉. "Autocloned Omni-directional Reflector for Blue Light LED". Thesis, 2012. http://ndltd.ncl.edu.tw/handle/61636792641537338111.
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碩士國立中央大學
光電科學研究所
100
Base on the theory of photonic crystal, an omni-directional reflector (ODR) for blue light LED was designed using finite-difference time-domain (FDTD) method. The fabrication method is combining the autocloned multilayer technique with anodized aluminum oxide (AAO) technique. The autocloned multilayer was fabricated using electron beam deposition and ion-beam-assisted deposition (IAD) system to coating multilayer on the AAO substrate.. Traditionally, the fabrication of 3-dimensional photonic crystals were using electron beam lithography technology which is complex and expensive. In this study, we use AAO method to fabricate a two- dimension hole-array substrate. This method is a low cost and easy process. Besides, the period and pore diameter can be controlled by applying the bias voltage, acid and reaction time. To compare with the electron beam lithography process, its large process area is one of the advantages. Then, 25 layers of autocloned multilayer were deposited on the two-dimension AAO substrate to achieve an ODR for blue light LED. Finally, the reflection of the ODR was measured using a spectrometer under different incident angles. The central wavelength shifting was measured and analyzed at 60̊ of incident angle. To compare with the planar multilayer high reflector, the autocloned multilayer high reflector can reduce 33.3% of central wavelength shifting. So, the autocloned multilayer high reflector performed an ODR for blue light LED successfully.
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Tseng, Yi-Chun y 曾逸群. "Study on light leakage improvement in blue LED Backlight". Thesis, 2014. http://ndltd.ncl.edu.tw/handle/92528609248917089772.
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碩士國立交通大學
工學院精密與自動化工程學程
102
In the past, several approaches of using light-emitting diodes (LEDs) to achieve high-quality color display have been used. The first approach involves mixing red–green–blue (RGB) colors to achieve white light. However, obtaining pure white light and light uniformity by using LEDs with RGB colors remains technically challenging. The second approach entails using a blue-light LED with white-light LEDs that comprise red–green phosphor. The blue-light LED excites the white light through the red and green phosphors. Currently, manufacturers can expand a never the same color gamut(NTSC) from 72% to 85%; however, such increase limits the improvement of color gamut. Another approach involves using quantum dot enhancement film to generate a wide color gamut, in which NTSC gamut increased from 72% to approximately100%. However, because blue-light LEDs differ from commonly used white-light LEDs, the use of blue LEDs engenders optical problems such as light leakage and glare appearing as a blue glow. Therefore, this study addressed the light leakage problem. The causes of light leakage were analyzed using optical simulation software, in which wall distance and angles were specified to identify optimal parameters. Subsequently, the extent to which overall light leakage improved was determined and display uniformity was enhanced. The experimental results showed that when the wall angle was 30°, the energy at the light-emitting side was the lowest and the overall display uniformity achieved 72.8%; thus, light leakage was effectively reduced.
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Meng, Hsin-Wei y 孟欣薇. "Increasing GaN Blue LED Light Extraction Efficiency With TRIZ". Thesis, 2008. http://ndltd.ncl.edu.tw/handle/09219717890272221911.
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碩士元智大學
工業工程與管理學系
96
Since the energy-saving and the global warming effect are becoming the topics concerned all around the world, the light emitting diode(LED) with the benefits of environmental friendliness, tiny volume, long service life and low energy consumption seems to be the new light source in the 21st century. Since the mid-1990s, GaN Blue LED has been of great interest because of its potential for optoelectronic application. One of the critical problems in a conventional GaN Blue LED chip was increasing light efficiency. With respect to the LED technology, the variety of materials and the manufacturing variations are the key points. In this study, the means Contradiction matrix and the innovative principles based TRIZ innovation process concerned would be put forth in the project. Contradictions caused by transition actions were formulated and resolved with the guidance of inventive principles that suggested conceptual guidelines for technical contradiction. More than four useful ideas were developed with the aid of the inventive principles. Many ideas have proven excellent performers for light extraction up to a 46 percent increase in average. And it can be found the brightness improvement and heat dissipation could be solved simultaneously. As for the innovation process to produce GaN Blue LED, the target will be raising the efficiency of light extraction.
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Chen, Shau-Jhang y 陳少章. "Studying surface luminesce distribution of blue-light LED by SNOM". Thesis, 2010. http://ndltd.ncl.edu.tw/handle/24499910667412956722.
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碩士國立中興大學
奈米科學研究所
98
We study the spacial luminance distribution of blue-ray light emitting diodes (LEDs) at different forward bias currents (I). The luminance distribution of the sample is observed by a scanning near-field optical microscope (SNOM) within a 2 um ×10um small area and also by an optical microscope (OM) for the view of a whole LED chips. We further investigate the spectra of the luminescence together with the distribution of a specific wavelength at various I. We found that the luminance strength of blue-ray LEDs fluctuates in the observation area. Below I = 4 mA, the variation of luminance strength increases as I increases. Overall, the ratio of the variation in the scanning area is below 15%. From the spectrum of the luminescence, the peak wavelength of this sample is 452 nm. The intensity variation of luminance strength at 452 nm increases when I increases. We also scan the intensity distribution at the wavelength of 452 nm, which is similar with the total luminance distribution.
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劉人傑. "Anti-Blue Light LED Polymer Packaging Materials Containing Energy Transfer Phosphor Powders". Thesis, 2018. http://ndltd.ncl.edu.tw/handle/hp5ux8.
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碩士國立交通大學
影像與生醫光電研究所
106
This paper successfully developed anti-blue light complex materials used in white light-emitting diodes. The anti-blue inorganic phosphor can transfer the energy from the blue light generated by the LED chip to a longer wavelength (greater than 450 nm) to the green or red light in the visible range by doping process. The short-wavelength blue light that harms eyes would be effectively reduced, which achieves the purpose of green energy and energy conservation. In addition, the anti-reflective layer can be coated on the surface of the LuAG phosphors provided from the Pro-Magic company through surface modification. Apart from achieving the effect of surface protection, the energy loss on the surface can also be reduced. The results of the measurement showed that the LuAG phosphors enhanced the fluorescence intensity after surface modification. Thereafter, LuAG phosphors were applied to the fluorescent glue and compared with that made of pure LuAG phosphors. The luminous efficiency of the LuAG phosphors showed better performance after the surface modification.
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Magni, Giada. "Photobiomodulation and purinergic signaling: in vivo and in vitro approaches for new and innovative treatments in skin fibrosis and remyelination". Doctoral thesis, 2020. http://hdl.handle.net/2158/1197181.
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Keloids are an exuberant response to cutaneous wound healing, characterized by an exaggerated synthesis of collagen probably due to the increase of fibroblasts activity and their proliferation rate. Currently, there are not definitive treatments or pharmacological therapies able to prevent keloid formation and its recurrence. In the last years, physical treatments have been proposed and among them the photobiomodulation therapy. In this work, the effects of Blue LED light (410-430 nm wavelength, 0.69 W/cm2 power density, 5÷60s treatment time) were evaluated on seven boundary keloid tissues by using two different colorimetric assays. Micro-Raman spectroscopy was used to explore direct effects of the Blue LED light on the endogenous cellular redox system and in particular to probe any variation in the oxidation state of the photosensitive heme-protein Cytochrome C (Cyt C) upon irradiation. We also investigated the effects of Blue LED light on membrane currents correlated to cell cycle modulation by patch-clamp recordings. Twenty-four hours after irradiation, a significant reduction of cell metabolism and proliferation was observed. The decrease in cell metabolism was maintained up to 48 hours when we found also an increased reduction in cell proliferation. Electrophysiological recordings showed an enhancement of voltage-dependent outward currents elicited by a depolarizing ramp protocol after a 30s irradiation. Data indicates that Blue LED light irradiation directly affects human keloid fibroblasts: it possesses a long lasting inhibitory effect on cell metabolism and proliferation whereas acutely increases membrane currents. Similar responses were obtained in our recent works conducted on human keloid tissues. The proposed photomodulation treatment by using Blue LED light represents a non-invasive approach in the management of hypertrophic scars and keloids.
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Yang, Tsan-Ming y 楊璨名. "Light extraction and far-field pattern of micro/nano-structured thin-GaN blue led". Thesis, 2010. http://ndltd.ncl.edu.tw/handle/60505073686931999212.
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碩士國立東華大學
光電工程研究所
98
Because the angle of the spontaneous carrier recombination radiation almost can be treated as isotropic in most of the semiconductor (ie.The radiation has the same intensity in all directions.). In this thesis, the study will focus on the carrier radiation recombination in the cavity. Therefore, by adding some methods, such as placing the DBR mirror structure[1-3] or the Sub-micro grating taken in my research under the active layer, it would improve the photon redistributing in order to extract more photon improving the efficiency of extracting photon(light) in the cavity of LED. I will be used metal to replace sapphire substrate in the simulation GaN structure. Then the structure became a vertical metal substrate of LED[4-5]. In order to increase the light extraction number from the plane, I use a periodic corrugated pattern structure to increase the light extraction efficiency[6]. I simulated eight type of sub-micron grating periodic structure. I found in cycle 0.6mm (the maximum of light extraction efficiency), Incoherent case (one time just put a point light source in emitting layer) is better than no structure nearly 3.99 times. Partial spatial coherent case (in light-emitting layer, a light source placed on three points) get 8.59 times, while the Stimulated emission case (put a point light source in the three light-emitting layer ) is about 9.91 times the available. Sub-micro grating can couple out of the guided mode. Then I use the wave number to explain the situation of the light touching the periodic grating structure. However, using the momentum space wave vector (see Figure 4-3) to investigate the efficiency of light can be found only in the relative-hour period (such as the cycle of 1.0mm or less), only way to determine the strength of its extraction efficiency, because the period is relatively large. The momentum space wave vector modes would be intersection each other too many. So eventually we can predict the light pattern and understand how to extraction the light from the cavity.
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Kuo, Yu Fang y 郭育芳. "Effects of LED Correlated Color Temperature on the Light Fastness of Blue Wool Standards". Thesis, 2015. http://ndltd.ncl.edu.tw/handle/20211750186832863528.
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碩士國立臺南藝術大學
博物館學與古物維護研究所
103
Light is a common cause of damage to collections. Paper, textile, binding media , dyes and pigments are particularly sensitive to light. Most of us recognize fading as a form of light damage, but this is only a superficial indication of deterioration that will extends to the physical and chemical structure of collections eventually. Most important, light provides energy to fuel the chemical reactions that produce deterioration. Light damage is cumulative and irreversible. Incandescent lamps have been phased out since 2010 in Taiwan and LED was the latest cutting edge lighting technology, considered as an alternative to traditional light sources. LED waves have swept the museum circle. There are some advantages of LED lighting, such as energy efficiency, ecologically friendly, response fast, small size, low quantity of heat and longer service lifetime. The limit of current technology restricts LED from so-claimed full performance concerning global illumination, color rendering and reliability. Therefore it is necessary to evaluate the use of LED lighting in museums. Blue wool standards were exposed to four types of white LED lamps under different color temperatures. Color changes were measured at each 15,000lx-hr interval twenty times. The accumulated exposed time were 300,000lx-hr. Test results showed that all LED lighting cause fading on blue wool standard grade 1 and the lower color temperature of light the fading rate was faster . The test result is different from former literatures may attributed to commercial LED lamps. The commercial lamps were made by different production and packaging processes based on cost and market trend considerations, such instability will be a potential damage to cultural relics. Color temperature as an indicator of light sources needs more evaluation analysis to testify its performance. It is important to develop a suitable illuminating system light sources in order to put white LED lamps into practical use as a museum light sources.
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Huang, Chia-Hsiang y 黃嘉祥. "Anti-Blue Light Containing Energy Transfer Phosphor Powders Applied in LED Polymer Packaging Materials". Thesis, 2018. http://ndltd.ncl.edu.tw/handle/445c2e.
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碩士國立交通大學
工學院半導體材料與製程設備學程
106
In this project, novel anti-blue light polymer composite materials are applied to the white light-emitting diodes (LEDs). By doping anti-blue light inorganic phosphor powder, polymer composite materials can absorb blue light originated from LED chips and then the energy of blue light can be transferred to the longer wavelength (wavelengths longer than 450 nm) or shifted to the emitting range between green light and red light. There are many advantages of reusing the blue wavelengths not only to avoid harming human eyes but also to improve the efficiencies of LEDs with broader color components. Through this way, the purpose of energy-saving and green energy can be yielded. In addition, the anti-blue inorganic (e.g. YAG) phosphor powders can be surface-modified with functional groups to enhance their compatibilities with polymers, and thus to improve the luminescent, mechanical, homogeneous, and fluidity of the anti-blue polymer composites.
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Ruan, Da-Ge y 阮大格. "Investigation of light extraction efficiency of plasmonic blue LED using dark field angle-resolved photoluminescence spectroscopy". Thesis, 2012. http://ndltd.ncl.edu.tw/handle/dpj6kj.
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碩士國立東華大學
光電工程學系
100
In this thesis, we discuss the InGaN/GaN multi-quantum wells (MQWs) LEDs with one dimensional (1D) plasmonic grating by using angle-resolved photoluminescence (ARPL) spectrometer. In experiment , we modify the period of structure、film thickness、different material of film to measure emitting property of the GaN LED. In experiment , InGaN/GaN LEDs sample is grown on 2 inch diameter. One dimensional plasmonic grating on the InGaN/GaN LEDs film is using e bean lithography. Centrifugal method is used to deposit Au nanoparticles film onto InGaN/GaN MQWs film. The period of plasmonic gratings are 0.3μm、0.5μm、0.75μm、1μm、2μm. Two polarization states, TEin –TMout mode and TMin –TEout mode, are used to measure the polarization dependent properties of the LED. The light extraction efficiency for different films are measured and discussed. The light extraction efficiency of the GaN grating with Au nanoparticle is TE-polarized dominated. However, as the plasmonic grating with Au nanoparticle monolayer, the light extraction efficiency becomes TM-polarized dominated.
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Chang, Che Ming y 張哲銘. "The new design with mixing R.G.B. LED(Red,Green,Blue Light EmittingDiode) for modern LCD(Liquid Crystal Displsay ) backlight system". Thesis, 2006. http://ndltd.ncl.edu.tw/handle/84944219590946823096.
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碩士國立高雄第一科技大學
光電工程研究所
94
ABSTRACT LED(Light Emitting Diode) backlight module for LCD(Liquid Crystal Displsay ) backlight system has its advantages of color saturation, electricity savings and environmental frienldiness,etc. However , white LED(Light Emitting Diode) is not popular and widely used at this moment due to blue light spectrum weights most of all over spectrum range, which degrade color saturation. Therefore, R.G.B LED(Red,Green,Blue Light Emitting Diode) light source plays significant role at modern LCD(Liquid Crystal Displsay ) backlight system. The paper proposes a newly developed light source module with mixing R.G.B. LED(Red,Green,Blue Light Emitting Diode) for modern LED(Light Emitting Diode) backlight system instead of white light LED(Light Emitting Diode) and traditional CCFL （Cold Cathode Fluorescent Lamp）. . This system consists of three parts, a newly designed symmetric mirror for complete color mixing, R.G. B LED(Red,Green,Blue Light Emitting Diode) light source and diffusion plate with newly designed microstructure for the improvement of light uniformity. The light module is designed and simulated by ASAP (Advanced Systems Analysis Program), in which a sample with 160mm×90mm( around 7 inch pane) are presented with sixteen LEDs light source. Good color saturation and excellent light uniformity are reached in this research. According to the result of the final simulation, we doesn’t need the light guide . We can get 75% Uniformity.
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Lu, Yu-Tsung y 呂育聰. "Improvement in light-output efficiency of InGaN/GaN blue LED by current blocking layer and surface passivation layer". Thesis, 2003. http://ndltd.ncl.edu.tw/handle/12498817582206414245.
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碩士國立成功大學
微電子工程研究所碩博士班
91
Because of improved epitaxial growth and advanced process technology, the quantum efficiencies of GaN-based LEDs are increased. However, the external quantum efficiencies are less significantly than that based on GaAs. One of the reasons is that non-uniform current spreading and the other is that light could be re-absorbed by material as a result of the high refractive indices of semiconductor materials and defects. In this thesis, we will discuss improvement of light-output efficiency for GaN-based LED. We have proposed some methods to improve in light-output efficiency of GaN-based LED, including AR coatings, current blocking layer, and a novel structure (Noah structure). In our experiments, the optimum thickness of SiO2 and SiNx coatings for GaN-based LED are 800Å and 300Å and the enhancement of light-output intensity of them are 18.5% and 11.6%, respectively. According to being proven by theory and experiment, SiO2 is the most appropriate material as AR coating for GaN-based LED. Based on the theory of uniform current spreading, we created a novel structure of GaN-based LED named after Noah structure according to its feature. Our goal is want to make current spreading uniformly and increase the light-output intensity. Besides, we fabricated GaN-based LED with SiO2 as current blocking layer inserted under p-pad. We found that the light-output intensity and external quantum efficiency for the GaN-based LED with a current blocking layer were not as significantly increased as our expectation compared to those for the conventional GaN-based LED. The reasons maybe were due to its good conductivity of transparent contact layer and its wide band-gap of GaN and its alloy and transparent substrate of GaN-based LED.
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Salgado, Fernando Flávio Pagels. "Fluorescent light vs. LED for Gloeothece sp. biomass and bioactive compounds production - a promising approach from blue biotechnology?" Master's thesis, 2017. https://hdl.handle.net/10216/110537.
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TSAI, YANG TUNG y 楊棟財. "A Study on the Ability to Protect ESD Event of Blue-Light LED form TLP HBM MM Measurement". Thesis, 2005. http://ndltd.ncl.edu.tw/handle/88597735820060354037.
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碩士大葉大學
電機工程學系碩士在職專班
93
The ability to resist the electrostatic discharge (ESD) of blue-light LED (Light emitting diode) is studied in this thesis. The ESD stress is performed with TLP、HBM and MM. Some solutions to increase the endurance of ESD are present in the last. At present, Gallium Nitride (GaN) and Silicon Carbide (SiC) are the two major groups to fabricate blue-light LED. But, there still have a lot of problems to overcome after manufacture. One of them is that it is very sensitive to ESD events, that is, the ability to resist ESD is very low under reverse bias mode. In this thesis, these ESD stresses are performed by TLP, HBM, and MM. The results are used to verify ESD ability according to the theory of TLP, HBM, MM. The optics microscope is uses to observe and analysis of the failure position. Now, in order to protect the component from ESD stress, at first, we have to improve the ability to resist ESD. second, strengthen manufacture, encapsulation, test, assembly, and reduce the production of the static source.
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Salgado, Fernando Flávio Pagels. "Fluorescent light vs. LED for Gloeothece sp. biomass and bioactive compounds production - a promising approach from blue biotechnology?" Dissertação, 2017. https://hdl.handle.net/10216/110537.
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Chen, Yi-Chin y 陳奕錦. "Influence of embedded voids in indium tin oxide current spreading layer on the light extraction efficiency of a blue LED". Thesis, 2013. http://ndltd.ncl.edu.tw/handle/06850335555867028748.
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碩士國立中興大學
奈米科學研究所
101
It this thesis, the influence of etched holes embedded in the indium tin oxide (ITO) transparent conductive layer on the performance of a blue LED is investigated. In this experiment, electron beam evaporation was employed to 250nm-thick ITO thin film on a 470nm GaN-based LED. Photo mask having various holes patterns of 0μm,6μm,8μm,10μm,12μm, respectively, were used to develop etched holes in the ITO layer of the LED. It was found that the light extraction efficiency of a blue LED can be enhanced by etched holes embedded in the ITO layer of the LED.
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Lin, En-Chieh y 林恩頡. "Analysis the protective effects of blue-light cutting spectacle lens against LED lighting induced visual physiological changes in the mouse model". Thesis, 2015. http://ndltd.ncl.edu.tw/handle/mn9fbk.
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Jia, Jin-An y 賈覲安. "Study of light extraction efficiency for blue-ray LEDs with micro structures". Thesis, 2012. http://ndltd.ncl.edu.tw/handle/05123358352950550324.
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碩士國立中央大學
光電科學研究所
100
In this thesis, we build the optical model by TracePro based on Monte Carlo ray tracing method. Under different substrate in GaN LED, we analyze the light extraction efficiency (LEE) with different chip shaping angles. In the case of the SiC-based GaN LEDs, the slanted angle in 60°, with lens encapsulation, the LEE reaches 52.24%. Furthermore, we analyze the enhancement of the directionality and the LEE when the slanted angles of the cone array are different by changing surface texture of Thin GaN LED. In the case of Thin-GaN LEDs with diffuse reflector, the slanted angle of 65°with lens encapsulation, where the LEE reaches 81.16%.
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Xue, Zhen y 薛震. "Sidewall Effect on the Blue/White Light Pattern of Sapphire-based LEDs". Thesis, 2017. http://ndltd.ncl.edu.tw/handle/qn8uy5.
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碩士國立中央大學
光電科學與工程學系
105
In this thesis, we analyzed the sidewall effect of the sapphire-based LED on the light pattern both blue light and white light. By using the ASAP software, we built up the light source model of sapphire-based LED in the case of the highly matched on the light pattern both bare LED and LED with lens. On the basis of the phosphor optical models developed in the solid-state lighting laboratory whose supervisor is Dr. Ching-Cherng Sun, yellow phosphor has been well established. We regarded the light pattern recorded from light source model of LED with lens as the emitting surface to trace the blue light and the yellow light of the LED with phosphor and the LED with phosphor and silicone lens. Comparing the white light pattern of experiment and simulation, we tried to adjust the light pattern of the emitting surface by introducing the weighting coefficient to change the power percentage of each emitting surface based on the same light pattern of each surface. In this case, we finally obtained a similar white light pattern of the simulation as the experiment. Due to the model of white LEDs established, we could develop the package efficiency and the optical performance based on sapphire-based LED.
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Chiang, Kuo-Chun y 蔣國軍. "The Study of Process Technique for Flip-Chip Blue Light Emitting Diodes (LEDs)". Thesis, 2005. http://ndltd.ncl.edu.tw/handle/05121410539852942397.
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Yeh, Tien-Shou y 葉天守. "Investigation of Beam Pattern and Light Extraction Efficiency of SMD-Type Blue LEDs". Thesis, 2007. http://ndltd.ncl.edu.tw/handle/92732156185871004512.
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碩士中興大學
精密工程學系所
95
Abstract The motivation of this thesis is to investigate the beam pattern of the blue light-emitting diode (LED) and the light extraction efficiency of the surface-mount LED package. In order to modify the emission beam pattern of the blue LED as well as to improve the light extraction efficiency of the LED package, the total internal reflection from the LED chip has to be destroyed by a suitable geometric shape of the lens. The incorporation of various refractive indexes of the lenses with the index-match encapsulant materials is also expected to further reduce the Fresnel loss and internal reflection effect. First, the emission beam pattern and the flux from the blue LED chip without any encapsulant material were measured and compared with the the optical simulation result to confirm its validity. After that, the surface-mount blue LED with an encapsulant material were measured and compared with the optical simulation result to verify the accuracy of the optical simulation. The above procedure was followed by the simulation of the surface-mount LED integrated with an optical lens. A comparison between the measured and simulated results was made to re-verify the accuracy of the optical simulation. Therefore, the data derived from the above works can be used as reference data for the LED package design. Based on these studies, the light extraction efficiency of the blue LED package can be improved by 48% and the beam pattern can be modified into 84 degree using the following package design: a lens with radius of curvature (3.358 mm); the lens height (3.83 mm), the refractive index of encapsulant (1.53), and lens (1.41). A moderate design of the LED package is very important in modifying the beam pattern and in enhancing the light extraction efficiency.
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林萬罡. "A study of pixel charging voltage and its leakage effect for TFT-LCD failure detection using blue light source instead of red one". Thesis, 2018. http://ndltd.ncl.edu.tw/handle/wke5q9.
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碩士中華大學
機械工程學系
106
In the panel industry, in addition to high process yield requirements, the ability to detect defects in products is also important. How to improve the detection capability is not only the control of the yield department, but also the equipment testing department. At present, in the pixel test of LCD, there are still some undetectable defects, if the amorphous silicon (a-Si) remains on the pixel signal line (Data Line), which will cause short circuit problems between the pixels and the data lines. The main research of this thesis is to explore a test methodology for the existing TFT detection machine using blue light source instead of the original red one. The absorption coefficient of amorphous silicon (a-Si) using blue light is larger than that of the red one. If there is a defect of amorphous silicon remaining between the pixel and signal line, two types of failures can be observed by the Voltage Imaging Optical System (VIOS): (1) The pixel leakage effect will be more significant, and its charging voltage will be lower than the ones of normal defect-free pixels. (2) The pixel charging voltage is shorted to the signal line, so the pixel voltage will be almost equal to the signal voltage. Therefore, this paper proposes a test methodology, which uses the chromatographic curve pixel distribution curve to effectively find the pixel defects by tradeoff the best charging waveform. The actual method is to set six sets of voltage test waveforms to find the most appropriate pixel charging voltage, and performance comparison analysis is also made.