ABSTRACT
Abstract The aim of this study is to investigate the effect of a continuous stream of pulses of monochromatic blue pulsed (BP) and a combination of blue and green pulsed (BGP) light-emitting diode (LED) light conditions on physiological responses. This study is an approach to clarify the most suitable LED combination and flickering frequency to evoke alertness when a continuous stream of pulsed LED light is delivered and may suggest applications of continuous pulsed light as support for task illumination for shift workers, hospital nurses, school students or office employees. Combinations were delivered by exposures of BPLED and BGPLED pulses at 100, 200, and 400 Hertz over two background light colors (BLC). Participants were exposed to 12 different light conditions in a counterbalanced procedure. By integrating measures of electroencephalogram (EEG) and pupil constriction; results suggested significant changes in responses during the interaction of BLC, LED, and EEG. Beta waves exhibited a statistically significance (p < 0.05) in arousal levels when exposed to BG light, although no active task was involved during exposure. Furthermore, pupil reacted with larger constriction towards BGPLED exposure than towards monochromatic BPLED exposure, thus demonstrating that a continuous stream of pulses can deliver the same irradiance as if delivered in a continuous flow and without affecting perception as no flickering was perceived in any of the conditions by a qualitative evaluation.
Resumen Este estudio tiene por objetivo determinar cuál es la combinación de luz LED más adecuada y la frecuencia de parpadeo que esta deba tener, para evocar un estado de alerta cuando se emite un flujo continuo de la misma al combinarla con una iluminación de ambiente; y poder sugerir aplicaciones como soporte para la iluminación de tareas para trabajadores por turnos, enfermeras, médicos, estudiantes; o en oficinas y hospitales. Es de original importancia resaltar que en el mercado no existe un producto comercial que se pueda ajustar para apoyar en el trabajo al estado de alerta, se tiene la limitante que estas son pruebas a nivel laboratorio y que posteriores pruebas serán necesarias para validar el producto final. El método usado se basó en las combinaciones que se administraron mediante exposiciones de luz azul pulsada (BPLED) y luz azul y verde combinadas (BGPLED) a frecuencias de 100, 200 y 400 Hz adicionadas a la iluminación ambiental (BLC). Los participantes fueron expuestos a 12 condiciones de luz diferentes en un experimento balanceado y contrapesado. Mediante la integración de medidas electroencefalográficas (EEG) y de constricción pupilar; los resultados sugirieron cambios significativos en las respuestas durante la interacción de BLC, LED y EEG. Las ondas beta mostraron una significancia estadística (p <0.05) en los niveles de activación cuando se expusieron a la luz BGPLED, además, la pupila reaccionó con una mayor constricción hacia la exposición a BGPLED que hacia la exposición BPLED monocromática, adicionalmente se demostró que un flujo continuo de pulsos puede proporcionar una irradiación igual a la que se emite en flujo continuo; se concluyó e identificó además la frecuencia (100 Hz) que mejor evoca estado de alerta encefalográfíca y sin afectar la percepción de los usuarios en cuanto a su percepción del ambiente de acuerdo a la evaluación cualitativa.
ABSTRACT
Introduction: The success of dental composites in restorative dentistry stems from their good aesthetic properties andadequate durability. The clinical performance of composite resins is directly related to the degree of monomer conversion afterphoto polymerization. Placing composites at an elevated temperature reduce their viscosity and increase the efficiency ofpolymerization. Heating the composite prior to placement in the cavity increases monomer conversion rate and therefore theduration of the irradiation period may be reduced.Purpose of Study: Evaluate and compare effect of pre-heating on surface roughness and microhardness of nanohybrid compositeresin subjected to two different temperatures and two different durations using light emitting diode curing unit (LED LCU).Methods: Nanohybrid composite resin was tested at two temperatures (37°C and 55°C) and pre-heating of composite wasdone using incubator at two durations (10 and 20 minutes) respectively. Samples were injected into cylindrical Teflon molds andthe top surface of the specimens were polymerized using LED LCU for 40 s. After preservation for 24 h, specimens checkedfor surface roughness and Vickers hardness measurements. Statistical analysis were performed using one-way analysis ofvariance and Tukey post hoc test at a level of significance of P < 0.05 for both surface roughness and microhardness.Results: Pre-heating of composite affect on microhardness and did not influence on surface roughness.Conclusion: Pre-heating of resin composite increases microhardness and no significant effect on roughness.
ABSTRACT
Bleaching of vital teeth is a very common practice nowadays prompted by high esthetic demands of patients. But bleaching agents are known to cause some transient damage to enamel microstructure, so the need arises to determine the effect of bleaching agents on the mineral content of enamel. Aim: To evaluate mineral loss from enamel using in-office bleaching agent Hydrogen Peroxide and the effect of LED and Laser activated bleaching agent on mineral loss from enamel. Methods: Forty human premolar crowns were divided into buccal and lingual specimens and 80 blocks of 4x4x3mm each were obtained. Samples were randomly divided into four groups of twenty each depending upon the beaching treatment and activation method. Group I – Hydrogen Peroxide without additional activation, Group II – Hydrogen Peroxide with additional activation by Diode Laser, Group III – Hydrogen Peroxide with additional activation by LED Light and Group IV – Control group. Amount of calcium and Phosphate loss was calculated using atomic absorption spectrophotometry. Results: Results showed that bleaching with hydrogen peroxide leads to calcium and phosphate loss from enamel with additional activation resulting in higher amounts of mineral loss especially with Laser activation. Conclusion: Bleaching agents result in calcium and phosphate loss from enamel with significantly high loss of minerals due to additional activation by Laser and LED Light. Therefore bleaching procedures must be followed by remineralization treatments to prevent damage to enamel.
ABSTRACT
Under different red (R):blue (B) photon flux ratios, the growth performance of rapeseed (Brassica napus L.) is significantly different. Rapeseed under high R ratios shows shade response, while under high B ratios it shows sun-type morphology. Rapeseed under monochromatic red or blue light is seriously stressed. Transcriptomic and proteomic methods were used to analyze the metabolic pathway change of rapeseed (cv. "Zhongshuang 11") leaves under different R:B photon flux ratios (including 100R:0B%, 75R:25B%, 25R:75B%, and 0R:100B%), based on digital gene expression (DGE) and two-dimensional gel electrophoresis (2-DE). For DGE analysis, 2054 differentially expressed transcripts (|log2(fold change)|≥1, q<0.005) were detected among the treatments. High R ratios (100R:0B% and 75R:25B%) enhanced the expression of cellular structural components, mainly the cell wall and cell membrane. These components participated in plant epidermis development and anatomical structure morphogenesis. This might be related to the shade response induced by red light. High B ratios (25R:75B% and 0R:100B%) promoted the expression of chloroplast-related components, which might be involved in the formation of sun-type chloroplast induced by blue light. For 2-DE analysis, 37 protein spots showed more than a 2-fold difference in expression among the treatments. Monochromatic light (ML; 100R:0B% and 0R:100B%) stimulated accumulation of proteins associated with antioxidation, photosystem II (PSII), DNA and ribosome repairs, while compound light (CL; 75R:25B% and 25R:75B%) accelerated accumulation of proteins associated with carbohydrate, nucleic acid, amino acid, vitamin, and xanthophyll metabolisms. These findings can be useful in understanding the response mechanisms of rapeseed leaves to different R:B photon flux ratios.
Subject(s)
Brassica napus/radiation effects , Brassica rapa/radiation effects , Carbon/chemistry , Chloroplasts/radiation effects , Computational Biology , Electrophoresis, Gel, Two-Dimensional , Gene Expression Regulation, Plant/radiation effects , Image Processing, Computer-Assisted , Light , Mass Spectrometry , Metabolic Networks and Pathways , Nitrogen/chemistry , Photons , Photosystem II Protein Complex/genetics , Plant Leaves/radiation effects , Plant Proteins/genetics , Proteome , Ribosomes , Transcription, Genetic , TranscriptomeABSTRACT
Malaria is a parasitic disease of major health significance that arrests the development of the tropical countries.We assembled an innovated LED light box for diagnosis of malaria, and examined for availability of the LED light box in the clinics of malaria endemic area in Solomon islands in the previous study. In the present study, we tried to use the LED light box for the practical use in the clinics with diagnostic service of malaria in Vanuatu (next country of Solomon Islands) for 1 year, and verified the availability and problems of the continual use of the LED light box.We identified the advantage of the use of LED light box in the diagnosis of malaria using microscopy. On the other hand, additional training of basic electricity is needed for microscopists who have little experience for electronics in the course of training of mictroscopists for the practical use of the LED light box.
ABSTRACT
OBJECTIVES: The purpose of this study was to measure the power density of light curing units transmitted through resin inlays fabricated with direct composite (Filtek Z350, Filtek Supreme XT) and indirect composite (Sinfony). MATERIALS AND METHODS: A3 shade of Z350, A3B and A3E shades of Supreme XT, and A3, E3, and T1 shades of Sinfony were used to fabricate the resin inlays in 1.5 mm thickness. The power density of a halogen light curing unit (Optilux 360) and an LED light curing unit (Elipar S10) through the fabricated resin inlays was measured with a hand held dental radiometer (Cure Rite). To investigate the effect of each composite layer consisting the resin inlays on light transmission, resin specimens of each shade were fabricated in 0.5 mm thickness and power density was measured through the resin specimens. RESULTS: The power density through the resin inlays was lowest with the Z350 A3, followed by Supreme XT A3B and A3E. The power density was highest with Sinfony A3, E3, and T1 (p < 0.05). The power density through 0.5 mm thick resin specimens was lowest with dentin shades, Sinfony A3, Z350 A3, Supreme XT A3B, followed by enamel shades, Supreme XT A3E and Sinfony E3. The power density was highest with translucent shade, Sinfony T1 (p < 0.05). CONCLUSIONS: Using indirect lab composites with dentin, enamel, and translucent shades rather than direct composites with one or two shades could be advantageous in transmitting curing lights through resin inlays.
Subject(s)
Composite Resins , Dental Enamel , Dentin , Hand , Inlays , Light , Pyridines , ThiazolesABSTRACT
Malaria is a parasitic disease of major health significance that arrests the development of the tropical countries, and the developmental education on malaria for the local residents has crucial effects for the successful control of malaria. In the present study, we tried to innovate an effective education program for a community primary school in a malaria endemic area of Solomon islands. The integrated program was consisted mainly with practical exercises of the surveillance of mosquito larvae that transmit malaria parasites, identification of the species of mosquito larvae and the mapping of the breeding sites and the localization of the residence of village people under the cooperation of the local residents and teachers. We successfully established a risk map showing the approximate localization of <i>Anopheles</i> larvae that transmits malaria. An impressive observation of mosquito larvae was performed with microscope equipped with LED light box in the dark classroom without electric power equipments. Though no students have ever observed the mosquito larvae and few students have some knowledge for malaria, all students replied that they learned about malaria with a deep interest by the educational program. Thus, this educational program is shown to be promising for the health education in the schools of malaria endemic area.
ABSTRACT
BACKGROUND: Phototherapy has been studied as an alternative option for the treatment of acne. Propionibacterium (P.) acnes produces endogenous porphyrins as a by-product of metabolism. Light of particular wavelengths activates the porphyrins and induces a photodynamic reaction which subsequently kills the P. acnes. OBJECTIVE: The purpose of this study was to evaluate and analyze the photoinactivation efficacy of different wavelengths against P. acnes in vitro. METHODS: Using an LED lamps to emit light of variable wavelengths (370 nm, 385 nm, 395 nm, 405 nm, 470 nm, 505 nm, 590 nm, 630 nm and 880 nm), we examined the change of P. acnes colonies on agar plates after irradiation for 1, 3, 6 and 12 hours. Further investigations were also performed by irradiation on liquid medium, once, twice or three times consecutively, with an interval of 24 hours. RESULTS: Light irradiation of wavelengths 385 nm, 395 nm, 405 nm and 470 nm, was found to decrease the number of P. acnes colonies on agar plates by about 50%. In liquid medium, we observed the photoinactivation effect of light irradiation on P. acnes with the wavelengths 370 nm, 385 nm, 395 nm, 405 nm and 470 nm. However, we observed no photoinactivation effect on P. acnes with the wavelengths 505 nm, 590 nm, 630 nm or 880 nm. CONCLUSION: By in vitro testing, we have demonstrated that light irradiation of wavelengths up to a maximum of 470 nm are effective in decreasing P. acnes and therefore may be a good alternative treatment modality for acne.
Subject(s)
Acne Vulgaris , Agar , Metabolism , Phototherapy , Porphyrins , Propionibacterium acnes , PropionibacteriumABSTRACT
OBJECTIVES: The purpose of this study was to observe the reaction kinetics and the degree of polymerization of composite resins when cured by different light sources and to evaluate the effectiveness of the blue Light Emitting Diode Light Curing Units (LED LCUs) compared with conventional halogen LCUs. MATERIALS AND METHODS: First, thermal analysis was performed by a differential scanning calorimeter (DSC). The LED LCU (Elipar Freelight, 320 mW/cm2) and the conventional halogen LCU (XL3000, 400 mW/cm2) were used in this study for curing three composite resins (SureFil, Z-250 and AEliteFLO). Second, the degree of conversion was obtained in the composite resins cured according to the above curing mode with a FTIR. Third, the measurements of depth of cure were carried out in accordance with ISO 4049 standards. Statistical analysis was performed by two-way ANOVA test at 95% levels of confidence and Duncan's procedure for multiple comparisons. RESULTS: The heat of cure was not statistically different among the LCUs (p > 0.05). The composites cured by the LED (Exp) LCUs were statistically more slowly polymerized than by the halogen LCU and the LED (Std) LCU (p < 0.05). The composite resin groups cured by the LED (Exp) LCUs had significantly greater degree of conversion value than by the halogen LCU and the LED (Std) LCU (p = 0.0002). The composite resin groups cured by the LED (Std) LCUs showed significantly greater depth of cure value than by the halogen LCU and the LED (Exp) LCU (p < 0.05).
Subject(s)
Composite Resins , Hot Temperature , Kinetics , Polymerization , Polymers , Spectroscopy, Fourier Transform InfraredABSTRACT
Purpose of this research is estimating polymerization depth of different source of light. XL 3000 for halogen light, Apollo 95E for plasma arc light and Easy cure for LED light source were used in this study. Different shade (B1 & A3) resin composites (Esthet-X, Dentsply, U.S.A.) were used to measure depth of cure. 1, 2, and 3 mm thick samples were light cured for three seconds, six seconds or 10 seconds with Apollo 95E and they were light cured with XL-3000 and Easy cure for 10 seconds, 20 seconds, or 40 seconds. Vicker's hardness test carried out after store samples for 24 hours in distilled water. Results were as following. 1. Curing time increases from all source of lights, curing depth increased(p0.05). 4. Groups that do polymerization using Plasma arc and LED source of light did not show Vicker's hardness difference according to color at surface and 1mm depth(p>0.05), but showed difference according to color at 2mm and 3mm depth(p<0.05). The results showed that Apollo 95E need more polymerization times than manufacturer's recommendation (3 seconds), and Easy cure need polymerization time of XL-3000 at least.