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Micro-hardness evaluation of a micro-hybrid composite resin light cured with halogen light, light-emitting diode and argon ion laser

RODE, Katia M.; FREITAS, Patricia M. de; LLORET, Patricia R.; POWELL, Lynn G.; TURBINO, Miriam L.
Tipo: Artigo de Revista Científica
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This in vitro study aimed to determine whether the micro-hardness of a composite resin is modified by the light units or by the thickness of the increment. Composite resin disks were divided into 15 groups (n = 5), according to the factors under study: composite resin thickness (0 mm, 1 mm, 2 mm , 3 mm and 4 mm) and light units. The light activation was performed with halogen light (HL) (40 s, 500 mW/cm(2)), argon ion laser (AL) (30 s, 600 mW/cm(2)) or light-emitting diode (LED) (30 s, 400 mW/cm(2)). Vickers micro-hardness tests were performed after 1 week and were carried out on the top surface (0 mm-control) and at different depths of the samples. Analysis of variance (ANOVA) and Tukey tests (P a parts per thousand currency signaEuro parts per thousand 0.05) revealed no statistically significant difference among the light units for the groups of 0 mm and 1 mm thickness. At 2 mm depth, the AL was not statistically different from the HL, but the latter showed higher micro-hardness values than the LED. In groups with 3 mm and 4 mm thickness, the HL also showed higher micro-hardness values than the groups activated by the AL and the LED. Only the HL presented satisfactory polymerization with 3 mm of thickness. With a 4 mm increment no light unit was able to promote satisfactory polymerization.; Sao Paulo Research Foundation/FAPESP[99/08433-4]; Sao Paulo Research Foundation/FAPESP[99/11408-1]

Effect of Cluster Multi-Diode Light Emitting Diode Therapy (LEDT) on Exercise-Induced Skeletal Muscle Fatigue and Skeletal Muscle Recovery in Humans

LEAL JUNIOR, Ernesto Cesar Pinto; LOPES-MARTINS, Rodrigo Alvaro Brandao; ROSSI, Rafael Paolo; MARCHI, Thiago De; BARONI, Bruno Manfredini; GODOI, Vanessa De; MARCOS, Rodrigo Labat; RAMOS, Luciano; BJORDAL, Jan Magnus
Fonte: WILEY-LISS Publicador: WILEY-LISS
Tipo: Artigo de Revista Científica
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Background and Objectives: There are some indications that low-level laser therapy (LLLT) may delay the development of skeletal muscle fatigue during high-intensity exercise. There have also been claims that LED cluster probes may be effective for this application however there are differences between LED and laser sources like spot size, spectral width, power output, etc. In this study we wanted to test if light emitting diode therapy (LEDT) can alter muscle performance, fatigue development and biochemical markers for skeletal muscle recovery in an experimental model of biceps humeri muscle contractions. Study Design/Materials and Methods: Ten male professional volleyball players (23.6 [SD +/- 5.6] years old) entered a randomized double-blinded placebo-controlled crossover trial. Active cluster LEDT (69 LEDs with wavelengths 660/850 nm, 10/30 mW, 30 seconds total irradiation time, 41.7J of total energy irradiated) or an identical placebo LEDT was delivered under double-blinded conditions to the middle of biceps humeri muscle immediately before exercise. All subjects performed voluntary biceps humeri contractions with a workload of 75% of their maximal voluntary contraction force (MVC) until exhaustion. Results: Active LEDT increased the number of biceps humeri contractions by 12.9% (38.60 [SD +/- 9.03] vs. 34.20 [SD +/- 8.68]...

Avaliação do uso do laser de baixa intensidade e do ligth-emitting diode (LED) no comportamento de fibroblastos e na redução da incidência da mucosite bucal em crianças sob tratamento quimioterápico; Evaluation of the use of low-intensity laser and Light-Emitting Diode (LED) on the behavior of fibroblasts and in reducing the incidence of oral mucositis in children under chemotherapy

Volpato, Luiz Evaristo Ricci
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 17/07/2009 PT
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Avaliou-se o uso do laser de baixa intensidade e do Light-Emitting Diode (LED) no comportamento de fibroblastos e na redução da incidência da mucosite bucal em crianças sob tratamento quimioterápico. Para tanto, o estudo foi executado em dois períodos experimentais distintos. No primeiro período, foi realizada a análise da viabilidade de fibroblastos Balb/c 3T3 cultivados sob déficit nutricional irradiados com laser vermelho (660nm, 40mW), laser infravermelho (780nm, 50mW) e LED vermelho (637 ± 15nm, 40mW) por 4 e 8 segundos através dos ensaios de redução do MTT e captação do vermelho neutro. No segundo período experimental realizouse ensaio clínico randomizado duplo-cego para avaliar a eficácia do laser vermelho (660nm, 40mW) e do LED vermelho (637 ± 15nm, 40mW) na redução da incidência e da severidade da mucosite bucal e da dor relacionada em crianças portadoras de câncer submetidas a quimioterapia utilizando-se o sistema de graduação da mucosite bucal da Organização Mundial de Saúde e a Escala de Dor de Faces Revisada associada à escala analógica visual. A análise estatística foi realizada utilizando-se o teste não paramétrico de Kruskal-Wallis e analise de variância do modelo linear geral com nível de significância de 5% (p = 0...

Assessment of the effectiveness of light-emitting diode and diode laser hybrid light sources to intensify dental bleaching treatment

Gomes Torres, Carlos Rocha; Barcellos, Daphne Camara; Batista, Graziela Ribeiro; Borges, Alessandra Buhler; Cassiano, Karla Viana; Pucci, Cesar Rogerio
Fonte: Informa Healthcare Publicador: Informa Healthcare
Tipo: Artigo de Revista Científica Formato: 176-181
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Objective. To evaluate the effectiveness of the color change of hybrid light-emitting diode (LED) and low-intensity infrared diode laser devices for activating dental bleaching and to verify the occurrence of a color regression with time. Material and methods. A total of 180 specimens obtained from human premolars were immersed in a coffee solution for 15 days for darkening and then divided into eight experimental groups (n = 20 in each) as follows: G1, bleaching without light; G2, bleaching with halogen light; G3, bleaching with a blue LED (1000 mW/470 nm) and a laser device (120 mW/795 nm) simultaneously; G4, bleaching with an LED emitting blue light (1000 mW/470 nm); G5, bleaching with a blue LED (800 mW/470 nm) and a laser device (500 mW/830 nm) simultaneously; G6, bleaching with a blue LED device (800 mW); G7, bleaching with a green LED (600 mW/530 nm) and a laser device (120 mW/795 nm) simultaneously; and G8, bleaching with a green LED (600 mW). Three measurements were performed (at baseline and 14 days and 12 months after bleaching) using a Vita Easyshade spectrophotometer. The data were submitted to two-way ANOVA and a Tukey test. Results. All groups showed significantly higher Delta E values than Group G1, with the exception of Group G8. Variations in the Delta E values at 14 days were significant when compared with those obtained at baseline and after 12 months. Conclusions. Light activation of the bleaching gel provided faster and more intense bleaching than use of the bleaching gel without light activation. Combinations of low-intensity diode lasers are ineffective as a bleaching gel activator. Color regression was observed after 12 months of storage.

Confocal scanning raman spectroscopy (CSRS) of an operating organic light-emitting diode

Paez-Sierra, B. A.; Gomes, Henrique L.
Fonte: AIP American Institute of Physics Publicador: AIP American Institute of Physics
Tipo: Conferência ou Objeto de Conferência
Publicado em //2010 ENG
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Organic molecules with semiconducting properties are becoming nowadays core of the organic-based electronic era. Although organic light emitting diodes (OLEDs) have already matured for commercial applications, they still require longer device lifetimes. Some of the long-standing challenges in OLED technology relay on degradation and failure mechanisms. Several authors observed that degradation and subsequent damage of OLEDs is accompanied by formation of dark non-emissive spots [1-2]. Implementation of the confocal scanning Raman spectroscopy (CSRS) measurements helps to understand the chemistry, physics of OLEDs and moreover to have better confidence on their quality assurance.

The use of light-emitting diodes to stimulate mitochondrial function and liver regeneration of partially hepatectomized rats

Castro-e-Silva,T.; Castro-e-Silva,O.; Kurachi,C.; Ferreira,J.; Zucoloto,S.; Bagnato,V.S.
Fonte: Associação Brasileira de Divulgação Científica Publicador: Associação Brasileira de Divulgação Científica
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/08/2007 EN
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The biostimulating effect of laser radiation has been observed in many areas of Medicine. However, there are still several questions to be answered, among them the importance of light coherence in the stimulatory process. In the present study, we used light-emitting diodes (LED) to promote the stimulation of liver regeneration after partial hepatectomy in rats. Fourteen male Wistar rats weighing 200-250 g were submitted to partial hepatectomy (70%) followed by LED light irradiation (630 nm) of the remaining part of the liver at two doses, i.e., 10 (N = 7) and 140 (N = 7) J/cm². A group irradiated with laser, 590 nm (N = 7, 15 J/cm²) was performed for the study of proliferating cell nuclear antigen-labeling index. Data are reported as mean ± SEM. Statistical comparisons of the groups were performed by analysis of variance for parametric measurements followed by the Bonferroni post-test, with the level of significance set at P < 0.05. Respiratory mitochondrial activity was increased in the irradiated groups (states 3 and 4; P < 0.05), with better results for the group exposed to the lower LED dose (10 J/cm²). The proliferating cell nuclear antigen-labeling index, by immunohistochemical staining, was similar for both LED-exposed groups (P > 0.05) and higher than for the control group (P < 0.05). The cell proliferation index obtained with LED and laser were similar (P > 0.05). In conclusion...

Analysis of the microtensile bond strength to enamel of two adhesive systems polymerized by halogen light or LED

Carvalho,Ana Paula Morales Cobra; Turbino,Míriam Lacalle
Fonte: Sociedade Brasileira de Pesquisa Odontológica - SBPqO Publicador: Sociedade Brasileira de Pesquisa Odontológica - SBPqO
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/12/2005 EN
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With the development of composite resin polymerization techniques, LEDs were introduced to the market place. Based on the studied literature, the aim of this study was to evaluate, through microtensile testing, the bond strength to enamel of a composite resin associated to a conventional (multi-bottle) adhesive system or to a self etching primer adhesive system, polymerized by halogen light or LED (light emitting diode). Bovine teeth were divided into 4 groups with 10 teeth each (n = 10). Then the adhesives Scotchbond Multipurpose Plus (3M-ESPE) and Clearfil SE Bond (Kuraray) were applied following the manufacturers’ instructions. Both systems were polymerized for 10 s by halogen light (Degulux Soft Start - Degussa Hulls) set at 550 mW/cm² or by LED (Kerr Demetron) set at 600 mW/cm². The composite resin Filtek Z-250 was applied in four 1 mm increments with the aid of a square, condensation silicon, 5 mm x 5 mm matrix, and polymerized by either of light sources for 40 s. Scotchbond Multipurpose Plus polymerized by halogen light presented the highest bond strength values (39.69 ± 7.07 MPa), and the other groups did not present statistically significant differences: Scotchbond Multipurpose Plus polymerized by LED (22.28 ± 2.63 MPa)...

Measurement of Extraction and Absorption Parameters in GaN-based Photonic-crystal Light-emitting Diodes

Matioli, Elison; Fleury, Blaise; Rangel, Elizabeth; Hu, Evelyn; Speck, James; Weisbuch, Claude
Fonte: American Institute of Physics Publicador: American Institute of Physics
Tipo: Artigo de Revista Científica
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The light extraction efficiency of photonic-crystal (PhC) light-emitting diodes (LEDs) relies on the competition between the PhC extraction and dissipation mechanisms of the guided light within the LED. This work presents the experimental determination of the PhC extraction length of each guided mode and the absorption coefficient of the active region (AR) and quantum wells (QWs) from the observation of the LED far-field emission using a high-resolution angle-spectrum-resolved measurement. The angular and spectral linewidths of the extracted guided modes reveal, depending on the spectral range, the modal extraction length of the PhCs, the AR absorption length, or a combination of both. Modes with a high confinement with the QWs presented a shorter absorption length compared with their extraction length by a shallow surface PhC (95-nm-deep), meaning that the AR absorption was a more efficient mechanism than the PhC extraction. The measured modal extraction length of the shallow surface PhC varied in the range of 55–120 μm, which determines the minimum dimensions of the device and the maximum acceptable dissipation length for an efficient extraction of the guided light by the PhCs. This paper presents also a discussion on the PhC designs that yield PhC extraction lengths shorter than other dissipation lengths...

White light emitting diode as liquid crystal display backlight; High brightness light emitting diode as liquid crystal display backlight

Soon, Chian Myau
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 33 leaves
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The discovery of high brightness (white) light emitting diode (LED) is considered as a real threat to the current lighting industry in various applications. One of the most promising sectors would be using white LED to replace the current Cold Cathode Fluorescent Light (CCFL) technology as the backlight of the large screen Liquid Crystal Display (LCD) screen due to the fact that LCD is a rapidly booming market.; by Chian Myau Soon.; Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 2007.; Includes bibliographical references.

Degree of conversion and hardness of an orthodontic resin cured with a light-emitting-diode and a quartz-tungsten-halogen light

Cerveira, Guilherme Pessôa; Berthold, Telmo Bandeira; Souto, André A.; Spohr, Ana Maria; Marchioro, Ernani Menezes
Fonte: Oxford; Porto Alegre Publicador: Oxford; Porto Alegre
Tipo: Artigo de Revista Científica
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The purpose of this study was to assess the influence of two light units, a quartz-tungsten-halogen (QTH) and a light-emitting-diode (LED) on the hardness and degree of conversion of an orthodontic composite resin.Sixty specimen disk were prepared from Transbond XT composite resin (3M-Unitek) and light-cured for 10, 20 and 30 seconds with a QTH light-curing unit (Curing Light XL 3000, 3M-Unitek) or with a LED light-curing unit (Ortholux, 3M-Unitek) for 5, 10 and 15 seconds. The composite resin polymerization was evaluated by infrared spectrophotometry (FTIR) and Knoop hardness number (KHN). The results were statistically analyzed using analysis of variance and Tukey multiple comparisons test (alpha=0.05). The highest KHN were obtained with the QTH at 30 (25.19 KHN) and 20 (24.01) seconds, which did not differ statistically, and with the LED 15 second (21.86) group. The QTH 10 second group (20.53) did not differ statistically from the QTH 20 second or LED 5, 15 (19.96) or 10 second (18.95) groups. According to FTIR, there was no statistical difference for the degree of conversion among the groups, QTH 10 (43.42%), QTH 20 (46.12%), QTH 30 (45.30%), LED 10 (47.02%) or LED 15 (47.24%) seconds. The lowest degree of conversion was obtained for the LED 5 second group (38.97%)...

Point defect engineered Si sub-bandgap light-emitting diode

Bao, Jiming; Tabbal, Malek; Kim, Taegon; Charnvanichborikarn, Supakit; Williams, James S; Aziz, Michael; Capasso, Federico
Fonte: Universidade Nacional da Austrália Publicador: Universidade Nacional da Austrália
Tipo: Journal article; Published Version Formato: 7 pages
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We present a novel approach to enhance light emission in Si and demonstrate a sub-bandgap light emitting diode based on the introduction of point defects that enhance the radiative recombination rate. Ion implantation, pulsed laser melting and rapid thermal annealing were used to create a diode containing a self-interstitial-rich optically active region from which the zero-phonon emission line at 1218 nm originates.

High power factor light-emitting diode driver on digital signal processor without electrolytic capacitor for high-power lighting

Chen, Y.; Zhou, J.; Hu, E.
Fonte: Taylor and Francis Publicador: Taylor and Francis
Tipo: Artigo de Revista Científica
Publicado em //2015 EN
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Electrolytic capacitor is a key factor that limits the life-time of the driver in a high-power light-emitting diode (LED) lighting. This article presents a high-power LED lighting driver on a digital signal processor without an electrolytic capacitor. The driver is composed of three stage circuits. The first stage is the boost power factor correction converter to achieve a high power factor. As it does not use an electrolytic capacitor, the output voltage ripple is larger, which directly affects the overall performance of the LED driver. Consequently, it must be optimized through the second and third stages. The second stage is the two-output LLC (Double inductance and capacitance) resonant converter, which is driven by a digital signal processor. This stage provides galvanic isolation and reduces voltage. The third stage is the two-input buck converter based on digital signal processor control that reduces the low-frequency ripple generated from the first two stages. Moreover, the regulation of each LED string current is achieved at this stage. The simulation and experimental results show that this LED lighting driver can achieve a high power factor and good constant current characteristics.; Yong Chen, Jun Zhou and Eric Hu; Published online: 20 Nov 2014

Analyse théorique et expérimentale de la diffusion de la lumière générée par une diode électroluminescente dans des répliques tissulaires; Theoretical and experimental analysis of the diffusion of light generated by a light emitting diode inside tissue-like media

LE POMMELLEC, Jean-Yves; L'HUILLIER, Jean-Pierre
Fonte: ELSEVIER Publicador: ELSEVIER
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The knowledge of the spatial distribution of light within a biological tissue exited by a light source (LASER or LED) is fundamental to achieve optimal photodynamic treatment. In this paper, we develop an analytical model relative to the diffuse fluence rate within a tissue-like medium irradiated by a continuous-wave light emitting diode (LED). The model is based on the two dimensional Fourier transform and applied to a homogeneous tissue slab. The total fluence rate along the axis of the medium was computed by adding the collimated and the diffuse components. The analytical solution was also used to study the depth evolution of the photon fluence rate as functions of the finite source beam size and the tissue optical parameters. Measurement results were performed using a tank filled with a liquid-simulating turbid medium (milk) illuminated with a LED beam. The experimental behaviour results agree with the theoretical predictions.

Effect of curing time on the bond strength of a bracket-bonding system cured with a light-emitting diode or plasma arc light

Dall'igna, Carine Maccarini; Marchioro, Ernani Menezes; Spohr, Ana Maria; Mota, Eduardo Gonçalves
Fonte: European Orthodontic Society; Porto Alegre Publicador: European Orthodontic Society; Porto Alegre
Tipo: Artigo de Revista Científica
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The purpose of this study was to assess the influence of two light units, a light-emitting diode (LED) and a plasma arc light (PAC), on the shear bond strength (SBS) of brackets bonded to enamel. Ninety bovine teeth were divided into six groups, according to the light-curing unit and exposure times used. In the LED (Ortholux; 3M-Unitek) group, the specimens were light cured for 5, 10, and 15 seconds. In the PAC (Apollo 95E; DenMed Technologies) group, the specimens were light cured for 3, 6, and 9 seconds. The brackets were bonded with Transbond XT (3M-Unitek), stored in distilled water at 37°C for 24 hours and then submitted to SBS testing in a universal testing machine. The adhesive remnant index (ARI) was used to evaluate the amount of adhesive remaining on the teeth. According to analysis of variance and Tukey multiple comparisons test, the highest mean SBS was obtained with the LED at 15 seconds (16.68 MPa), which did not significantly differ from the LED 10 (14.76 MPa) or 5 (13.92 MPa) second groups (P > 0.05). The LED 10 and 5 second groups were not significantly different from the PAC 9 second group (12.66 MPa) or from the PAC 6 second group (9.96 MPa). The lowest mean SBS was obtained with the PAC 3 second group (8.29 MPa)...

Wearable red–green–blue quantum dot light-emitting diode array using high-resolution intaglio transfer printing

Choi, Moon Kee; Yang, Jiwoong; Kang, Kwanghun; Kim, Dong Chan; Choi, Changsoon; Park, Chaneui; Kim, Seok Joo; Chae, Sue In; Kim, Tae-Ho; Kim, Ji Hoon; Hyeon, Taeghwan; Kim, Dae-Hyeong
Fonte: Nature Pub. Group Publicador: Nature Pub. Group
Tipo: Artigo de Revista Científica
Publicado em 14/05/2015 EN
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Deformable full-colour light-emitting diodes with ultrafine pixels are essential for wearable electronics, which requires the conformal integration on curvilinear surface as well as retina-like high-definition displays. However, there are remaining challenges in terms of polychromatic configuration, electroluminescence efficiency and/or multidirectional deformability. Here we present ultra-thin, wearable colloidal quantum dot light-emitting diode arrays utilizing the intaglio transfer printing technique, which allows the alignment of red–green–blue pixels with high resolutions up to 2,460 pixels per inch. This technique is readily scalable and adaptable for low-voltage-driven pixelated white quantum dot light-emitting diodes and electronic tattoos, showing the best electroluminescence performance (14,000 cd m−2 at 7 V) among the wearable light-emitting diodes reported up to date. The device performance is stable on flat, curved and convoluted surfaces under mechanical deformations such as bending, crumpling and wrinkling. These deformable device arrays highlight new possibilities for integrating high-definition full-colour displays in wearable electronics.

Influence of composite restorative materials and light-curing units on diametrical tensile strength

Tolosa,Maria Cecília Caldas Giorgi; Paulillo,Luís Alexandre Maffei Sartini; Giannini,Marcelo; Santos,Alex José Souza dos; Dias,Carlos Tadeu dos Santos
Fonte: Sociedade Brasileira de Pesquisa Odontológica - SBPqO Publicador: Sociedade Brasileira de Pesquisa Odontológica - SBPqO
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/06/2005 EN
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The aim of this study was to evaluate the diametrical tensile strength (DTS) of three light-curing photo-activated composites with two different light curing units (LCU). Three types of dental restorative composites were used in this study: micro filled A110 (3M Espe); P60 (3M Espe) for posterior restorations, and micro-hybrid Charisma (Heraeus-Kulzer). The two LCUs were: halogen light (HAL) (Degulux, Degussa) and blue light emitting diode (LED) (Ultrablue, DMC). Resin composite specimens were inserted incrementally into a Teflon split mold meas-uring 3 mm in depth and 6 mm in internal diameter, and cured using either LCU (n = 10). Specimens were placed into a dark bottle containing distilled water at 37°C for 7 days. DTS tests were performed in a Universal Testing Machine (0.5 mm/min). Data were submitted to two-way ANOVA and Tukey's test. Results were (MPa): A110/HAL: 276.50 ± 62.94ª; A110/LED: 306.01 ± 65.16ª; P60/HAL: 568.29 ± 60.77b and P60/LED: 543.01 ± 83.65b; Charisma/HAL: 430.94 ± 67.28c; Charisma/LED: 435.52 ± 105.12c. Results suggested that no significant difference in DTS was obtained with LCUs for the same composite. However, resin composite restorative materials presented different DTS.

Color stability of composites subjected to accelerated aging after curing using either a halogen or a light emitting diode source

Pires-de-Souza,Fernanda de Carvalho Panzeri; Garcia,Lucas da Fonseca Roberti; Hamida,Hisham Mohamad; Casemiro,Luciana Assirati
Fonte: Fundação Odontológica de Ribeirão Preto Publicador: Fundação Odontológica de Ribeirão Preto
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2007 EN
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The purpose of this study was to evaluate, in vitro, the color stability of three composite resins of two different shades (A3 and C3) cured with either a quartz tungsten halogen (QTH) or a light emitting diode (LED) source. Forty specimens (20 x 2 mm) were prepared for each composite (Tetric Ceram®, Heliomolar® and Esthet-X®), being 20 for each shade. In each group, 10 specimens were light-cured using the QTH unit and 10 with the LED source. The shade of the materials was evaluated before and after submitting the specimens to artificial accelerated aging (4 h UV-B/4 h condensing vapor), using a reflection spectrophotometer. deltaE means were calculated and analyzed statistically by 2-way ANOVA and Tukey's test at 5% significance level. Both A3 and C3 shades of Esthet-X composite resin showed the lowest color change when cured with the QTH light, while Tetric C3 cured with the QTH light showed the highest color change.

Phototoxic action of light emitting diode in the in vitro viability of Trichophyton rubrum

Amorim,José Cláudio Faria; Soares,Betania Maria; Alves,Orley Araújo; Ferreira,Marcus Vinícius Lucas; Sousa,Gerdal Roberto; Silveira,Lívio de Barros; Piancastelli,André Costa Cruz; Pinotti,Marcos
Fonte: Sociedade Brasileira de Dermatologia Publicador: Sociedade Brasileira de Dermatologia
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/04/2012 EN
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BACKGROUND: Trichophyton rubrum is the most common agent of superficial mycosis of the skin and nails causing long lasting infections and high recurrence rates. Current treatment drawbacks involve topical medications not being able to reach the nail bed at therapeutic concentrations, systemic antifungal drugs failing to eradicate the fungus before the nails are renewed, severe side effects and selection of resistant fungal isolates. Photodynamic therapy (PDT) has been a promising alternative to conventional treatments. OBJECTIVES: This study evaluated the in vitro effectiveness of toluidine blue O (TBO) irradiated by Light emitting diode (LED) in the reduction of T. rubrum viability. METHODS: The fungal inoculums' was prepared and exposed to different TBO concentrations and energy densities of Light emitting diode for evaluate the T. rubrum sensibility to PDT and production effect fungicidal after photodynamic treatment. In addition, the profiles of the area and volume of the irradiated fungal suspensions were also investigated. RESULTS: A small reduction, in vitro, of fungal cells was observed after exposition to 100 µM toluidine blue O irradiated by 18 J/cm² Light emitting diode. Fungicidal effect occurred after 25 µM toluidine blue O irradiation by Light emitting diode with energy density of 72 J/cm². The analysis showed that the area and volume irradiated by the Light emitting diode were 52.2 mm² and 413.70 mm³...

Point Defect Engineered Si Sub-Bandgap Light-emitting Diodes

Bao, Jiming; Charnvanichborikarn, Supakit; Yang, Yu; Tabbal, Malek; Shin, Byungha; Wong-Leung, Yin-Yin (Jennifer); Williams, James; Aziz, Michael; Capasso, Federico
Fonte: SPIE - The International Society for Optical Engineering Publicador: SPIE - The International Society for Optical Engineering
Tipo: Conference paper
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We present a novel approach to enhance light emission in Si and demonstrate sub-bandgap light-emitting diodes (LED) based on the introduction of point defects. Ion implantation, pulsed laser melting and rapid thermal annealing were used to create LEDs con

Efficient Light-Emitting Diodes Based on Nanocrystalline Perovskite in a Dielectric Polymer Matrix

Li, Guangru; Tan, Zhi-Kuang; Di, Dawei; Lai, May Ling; Jiang, Lang; Lim, Jonathan Hua-Wei; Friend, Richard H.; Greenham, Neil C.
Fonte: ACS Publicador: ACS
Tipo: Article; published version
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This is the final version of the article. It first appeared from ACS via http://dx.doi.org/10.1021/acs.nanolett.5b00235; Electroluminescence in light-emitting devices relies on the encounter and radiative recombination of electrons and holes in the emissive layer. In organometal halide perovskite light-emitting diodes, poor film formation creates electrical shunting paths, where injected charge carriers bypass the perovskite emitter, leading to a loss in electroluminescence yield. Here, we report a solution-processing method to block electrical shunts and thereby enhance electroluminescence quantum efficiency in perovskite devices. In this method, a blend of perovskite and a polyimide precursor dielectric (PIP) is solution-deposited to form perovskite nanocrystals in a thin-film matrix of PIP. The PIP forms a pinhole-free charge-blocking layer, while still allowing the embedded perovskite crystals to form electrical contact with the electron- and hole-injection layers. This modified structure reduces nonradiative current losses and improves quantum efficiency by 2 orders of magnitude, giving an external quantum efficiency of 1.2%. This simple technique provides an alternative route to circumvent film formation problems in perovskite optoelectronics and offers the possibility of flexible and high-performance light-emitting displays.; The authors acknowledge funding from the Gates Cambridge Trust...