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Sample records for led light curing

  1. Curing depth of composite resin light cured by LED and halogen light-curing units

    Science.gov (United States)

    Calixto, L. R.; Lima, D. M.; Queiroz, R. S.; Rastelli, A. N. S.; Bagnato, V. S.; Andrade, M. F.

    2008-11-01

    The purpose of this study was to evaluate the polymerization effectiveness of a composite resin (Z-250) utilizing microhardness testing. In total, 80 samples with thicknesses of 2 and 4 mm were made, which were photoactivated by a conventional halogen light-curing unit, and light-curing units based on LED. The samples were stored in water distilled for 24 h at 37°C. The Vickers microhardness was performed by the MMT-3 microhardness tester. The microhardness means obtained were as follows: G1, 72.88; G2, 69.35; G3, 67.66; G4, 69.71; G5, 70.95; G6, 75.19; G7, 72.96; and G8, 71.62. The data were submitted to an analysis of variance (ANOVA’s test), adopting a significance level of 5%. The results showed that, in general, there were no statistical differences between the halogen and LED light-curing units used with the same parameters.

  2. Shortest exposure time possible with LED curing lights

    NARCIS (Netherlands)

    Busemann, I.; Lipke, C.; Schattenberg, A.V.M.B.; Willershausen, B.; Ernst, C.P.

    2011-01-01

    PURPOSE: To investigate the shortest exposure time of different light emitting diode (LED)-curing devices for different resin composites in a clinically relevant laboratory model. METHODS: Nine LED curing devices (Bluephase, Bluephase 16i, Bluephase G2, Bluephase 20i/Ivoclar Vivadent, DEMI/sds Kerr,

  3. LED Curing Lights and Temperature Changes in Different Tooth Sites

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    E. Armellin

    2016-01-01

    Full Text Available Objectives. The aim of this in vitro study was to assess thermal changes on tooth tissues during light exposure using two different LED curing units. The hypothesis was that no temperature increase could be detected within the dental pulp during polymerization irrespective of the use of a composite resin or a light-curing unit. Methods. Caries-free human first molars were selected, pulp residues were removed after root resection, and four calibrated type-J thermocouples were positioned. Two LED lamps were tested; temperature measurements were made on intact teeth and on the same tooth during curing of composite restorations. The data was analyzed by one-way analysis of variance (ANOVA, Wilcoxon test, Kruskal-Wallis test, and Pearson’s χ2. After ANOVA, the Bonferroni multiple comparison test was performed. Results. Polymerization data analysis showed that in the pulp chamber temperature increase was higher than that without resin. Starlight PRO, in the same condition of Valo lamp, showed a lower temperature increase in pre- and intrapolymerization. A control group (without composite resin was evaluated. Significance. Temperature increase during resin curing is a function of the rate of polymerization, due to the exothermic polymerization reaction, the energy from the light unit, and time of exposure.

  4. LED vs halogen light-curing of adhesive-precoated brackets.

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    Mirabella, Davide; Spena, Raffaele; Scognamiglio, Giovanni; Luca, Lombardo; Gracco, Antonio; Siciliani, Giuseppe

    2008-09-01

    To test the hypothesis that bonding with a blue light-emitting diode (LED) curing unit produces no more failures in adhesive-precoated (APC) orthodontic brackets than bonding carried out by a conventional halogen lamp. Sixty-five patients were selected for this randomized clinical trial, in which a total of 1152 stainless steel APC brackets were employed. In order to carry out a valid comparison of the bracket failure rate following use of each type of curing unit, each patient's mouth was divided into four quadrants. In 34 of the randomly selected patients, designated group A, the APC brackets of the right maxillary and left mandibular quadrants were bonded using a halogen light, while the remaining quadrants were treated with an LED curing unit. In the other 31 patients, designated group B, halogen light was used to cure the left maxillary and right mandibular quadrants, whereas the APC brackets in the remaining quadrants were bonded using an LED dental curing light. The bonding date, the type of light used for curing, and the date of any bracket failures over a mean period of 8.9 months were recorded for each bracket and, subsequently, the chi-square test, the Yates-corrected chi-square test, the Fisher exact test, Kaplan-Meier survival estimates, and the log-rank test were employed in statistical analyses of the results. No statistically significant difference in bond failure rate was found between APC brackets bonded with the halogen light-curing unit and those cured with LED light. However, significantly fewer bonding failures were noted in the maxillary arch (1.67%) than in the mandibular arch (4.35%) after each light-curing technique. The hypothesis cannot be rejected since use of an LED curing unit produces similar APC bracket failure rates to use of conventional halogen light, with the advantage of a far shorter curing time (10 seconds).

  5. Comparative Evaluation of Shear Bond Strength and Debonding Characteristics using Conventional Halogen Light Curing Unit and LED Light Curing Unit: An in vitro Study

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    Amit Bhardwaj

    2013-01-01

    Conclusion: The result of this study showed promise for the orthodontic application of LED as light curing units and 20 seconds of exposure time is adequate for both LED and Halogen light, since increasing the curing time to 40 seconds showed no significant difference.

  6. Guidelines for the selection, use, and maintenance of LED light-curing units - Part 1.

    Science.gov (United States)

    Shortall, A C; Price, R B; MacKenzie, L; Burke, F J T

    2016-10-21

    Light curing is a critical step in the restorative process when using light-activated resin-based composites, but it is frequently not given the attention it deserves. The selection of a reliable light curing unit (LCU) that meets the practitioner's needs is an important equipment purchase. Using an inappropriate LCU may seriously compromise the quality of care without the practitioner realising their mistake until years later. The importance of the subject is reflected by the rapidly increasing use of light-cured composites and the decline in the use of amalgam. Many changes have occurred in the equipment and materials available for making light-cured restorations in the last twenty years. This article is part of a two-part series that will describe those changes and recommend guidelines for the selection, use, and maintenance of light emitting diode light-curing units (LED LCUs). This paper (Part 1) discusses terminology, clinical studies, the development of LCUs in dentistry, the aims of light-curing, and the need to deliver an adequate amount of energy. The interaction between light source and material is briefly described to demonstrate the complex nature of the resin photopolymerisation process.

  7. Evaluation of light intensity output of QTH and LED curing devices in various governmental health institutions.

    Science.gov (United States)

    Al Shaafi, Mm; Maawadh, Am; Al Qahtani, Mq

    2011-01-01

    The purpose of this study was to evaluate the light intensity output of quartz-tungsten-halogen (QTH) and light emitting diode (LED) curing devices located at governmental health institutions in Riyadh, Saudi Arabia.Eight governmental institutions were involved in the study. The total number of evaluated curing devices was 210 (120 were QTH and 90 were LED). The reading of the light intensity output for each curing unit was achieved using a digital spectrometer; (Model USB4000 Spectrometer, Ocean Optics Inc, Dunedin, FL, USA). The reading procedure was performed by a single investigator; any recording of light intensity below 300 mW/cm2 was considered unsatisfactory.The result found that the recorded mean values of light intensity output for QTH and LED devices were 260 mW/cm2 and 598 mW/cm2, respectively. The percentage of QTH devices and LED devices considered unsatisfactory was 67.5% and 15.6%, respectively. Overall, the regular assessment of light curing devices using light meters is recommended to assure adequate output for clinical use.

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

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    Bandéca, M. C.; El-Mowafy, O.; Saade, E. G.; Rastelli, A. N. S.; Bagnato, V. S.; Porto-Neto, S. T.

    2009-05-01

    The indirect adhesive procedures constitute recently a substantial portion of contemporary esthetic restorative treatments. The resin cements have been used to bond tooth substrate and restorative materials. Due to recently introduction of the self-bonding resin luting cement based on a new monomer, filler and initiation technology has become important to study the degree of conversion of these new materials. In the present work the polymerization reaction and the filler content of dual-cured dental resin cements were studied by means of infra-red spectroscopy (FT-IR) and thermogravimetry (TG). Twenty specimens were made in a metallic mold (8 mm diameter × 1 mm thick) from each of 2 cements, Panavia® F2.0 (Kuraray) and RelyX™ Unicem Applicap (3M/ESPE). Each specimen was cured with blue LED with power density of 500 mW/cm2 for 30 s. Immediately after curing, 24 and 48 h, and 7 days DC was determined. For each time interval 5 specimens were pulverized, pressed with KBr and analyzed with FT-IR. The TG measurements were performed in Netzsch TG 209 under oxygen atmosphere and heating rate of 10°C/min from 25 to 700°C. A two-way ANOVA showed DC (%) mean values statistically significance differences between two cements ( p cements ( p > 0.05). The Relx-Y™ Unicem mean values were significantly higher than Panavia® F 2.0. The degree of conversion means values increasing with the storage time and the filler content showed similar for both resin cements.

  9. Evaluation of wear rate of dental composites polymerized by halogen or LED light curing units

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    Alaghehmand H.

    2006-08-01

    Full Text Available Background and Aim: Sufficient polymerization is a critical factor to obtain optimum physical properties and clinical efficacy of resin restorations. The aim of this study was to evaluate wear rates of composite resins polymerized by two different systems Light Emitting Diodes (LED to and Halogen lamps. Materials and Methods: In this laboratory study, 20 specimens of A3 Tetric Ceram composite were placed in brass molds of 2*10*10 mm dimensions and cured for 40 seconds with 1 mm distance from surface. 10 specimens were cured with LED and the other 10 were cured with Halogen unit. A device with the ability to apply force was developed in order to test the wear of composites. After storage in distilled water for 10 days, the specimens were placed in the wear testing machine. A chrome cobalt stylus with 1.12 mm diameter was applied against the specimens surfaces with a load of 2 kg. The weight of each samples before and after 5000, 10000, 20000, 40000, 80000 and 120000 cycles was measured using an electronic balance with precision of 10-4 grams. Data were analyzed using t test and paired t test. P0.05. Conclusion: Based on the results of this study, LED and halogen light curing units resulted in a similar wear rate in composite resin restorations.

  10. Evaluation of microleakage of class II dental composite resin restorations cured with LED or QTH dental curing light; Blind, Cluster Randomized, In vitro cross sectional study.

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    Zakavi, Faramarz; Golpasand Hagh, Leila; Sadeghian, Soheila; Freckelton, Virginia; Daraeighadikolaei, Arash; Ghanatir, Elham; Zarnaghash, Najmeh

    2014-07-03

    The aim of this study is to compare the microleakage of Class II dental composite resin restorations which have been cured by three different LED (light emitting diode) light curing modes compared to control samples cured by QTH (quartz tungsten halogen) light curing units (LCUs), to determine the most effective light curing unit and mode of curing. In this experimental study, class II cavities were prepared on 100 sound human premolars which have been extracted for orthodontic treatment. The teeth were randomly divided into four groups; three experimental and one control group of 25 teeth each. Experimental groups were cured by either conventional, pulse-delay, or ramped curing modes of LED. The control group was cured for 20 seconds by QTH. The restorations were thermocycled (1000 times, between 5 and 55°C, for 5 seconds dwell time), dyed, sectioned mesio-distally and viewed under stereo-microscope (40×) magnification. Teeth were then scored on a 0 to 4 scale based on the amount of microleakage. The data were analyzed by Chi-square test.No significant difference was demonstrated between the different LCUs (light curing units), or modes of curing, at the enamel side (p > 0.05). At the dentin side, all modes of LED curing could significantly reduce microleakage (p curing improves marginal integrity and seal. High intense curing endangers those aims. Comparison between the three LED mode cured composite resin restorations and QTH curing showed LED curing in all modes is more effective than QTH for reducing microleakage. Both LED and QTH almost completely eliminate the microleakage on the enamel side, however none of them absolutely eliminated microleakage on the dentin side.

  11. Effect of LED light-curing time for the adhesive resin on the modulus of elasticity.

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    Senawongse, Pisol; Harnirattisai, Choltacha; Otsuki, Masayuki; Tagami, Junji

    2007-06-01

    To evaluate the elastic modulus of successive layers where an adhesive resin was cured by different light-curing times. Eighty dentin discs which were 2 mm thick were prepared from 40 sound third molars. The dentin discs were further divided into four groups and bonded with 3M Single Bond 2 and cured with an LED for 5, 10, 15 and 20s. Bonded specimens were restored with a microhybrid resin composite. Specimens were cut perpendicular to the resin dentin interface, embedded in epoxy resin, and polished. Polished specimens were evaluated for the elastic modulus at the layer of dentin, hybrid layer, adhesive resin, and resin composite at 24 hours after preparation. Light-curing times influenced the elastic modulus of hybrid layer and adhesive resin. The significant differences of elastic modulus among successive layers were found. The results suggested that extension of light-curing times of adhesive resin from 5 to 20 seconds increased the mechanical properties of the resin dentin interface.

  12. Effectiveness of composite resin polymerization using light-emitting diodes (LEDs) or halogen-based light-curing units

    OpenAIRE

    Micali,Bianca; Basting,Roberta Tarkany

    2004-01-01

    The clinical performance of composite resins is greatly influenced by the quality of the light-curing unit used. The aim of this study was to compare the efficiency of a commercial light-emitting diode (LED) with that of a halogen-based light-curing unit by means of dye penetration of a micro hybrid composite resin. The composite resin evaluated was Filtek Z250 (3M Dental). The composite was filled into acrylic moulds that were randomly polymerized for 40 seconds by each of the light-emitting...

  13. Evaluation of shear bond strength of orthodontic brackets using trans-illumination technique with different curing profiles of LED light-curing unit in posterior teeth

    OpenAIRE

    Heravi, Farzin; Moazzami, Saied Mostafa; Ghaffari, Negin; Jalayer, Javad; Bozorgnia, Yasaman

    2013-01-01

    Background Although using light-cured composites for bonding orthodontic brackets has become increasingly popular, curing light cannot penetrate the metallic bulk of brackets and polymerization of composites is limited to the edges. Limited access and poor direct sight may be a problem in the posterior teeth. Meanwhile, effectiveness of the trans-illumination technique is questionable due to increased bucco-lingual thickness of the posterior teeth. Light-emitting diode (LED) light-curing unit...

  14. Effect of reduced exposure times on the microhardness of nanocomposites polymerized by QTH and second-generation LED curing lights.

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    Marchan, S M; White, D; Smith, W A; Raman, V; Coldero, L; Dhuru, V

    2011-01-01

    This study investigated the effectiveness of polymerization of various curing regimes on five nanocomposite restorative materials—Z350, Grandio, Clearfil Majesty Esthetic, Ice and Tetric EvoCeram—by utilizing microhardness measurements. Five (n=5) disc-shaped specimens of each material were subjected to one of three curing regimes: curing with a halogen light for 20 seconds, curing with an LED light for 20 seconds and curing with an LED light for 10 seconds. Immediately following curing, hardness measurements were made with a Vickers indenter at five different locations on both the top and bottom surfaces of each disc. The mean for each surface was calculated. Data were analyzed using a one-way ANOVA and post-hoc Tukey HSD (α=0.05). The results demonstrated that among the Z350 composite samples, top and bottom microhardness values showed no statistical differences when cured with the halogen 20 second or LED 20 second regimes (p>0.05). Comparison of the top and bottom values of discs cured with the LED 10 second regime demonstrated significant differences (pGrandio samples cured with the halogen 20 second regime showed no statistical differences between top and bottom microhardness values (p>0.05); however, the bottom values of Grandio discs cured with the LED 20 second and 10 second regimes were significantly lower when compared with top surface values (p=0.001 and pGrandio, while they were adequate for curing Clearfil Majesty Esthetic, Ice and Tetric EvoCeram.

  15. Effects of distance from tip of LED light-curing unit and curing time on surface hardness of nano-filled composite resin

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    Shafadilla, V. A.; Usman, M.; Margono, A.

    2017-08-01

    Polymerization process depends on several variables, including the hue, thickness, and translucency of the composite resin, the size of the filler particles, the duration of exposure to light (the curing time), the intensity of the light, and the distance from the light. This study aimed to analyze the effects of the distance from the tip of the light-emitting diode (LED) light-curing unit and of curing time on the surface hardness of nano-filled composite resin. 60 specimens were prepared in a mold and divided into 6 groups based on various curing distances and times: 2 mm, 5 mm, and 8 mm and 20 seconds and 40 seconds. The highest surface hardness was seen in the group both closest to the tip and having the longest curing time, while the lowest hardness was seen in the group both farthest from the tip and having the shortest curing time. Significant differences were seen among the various tip distances, except for in the two groups that had 8-mm tip distances, which had no significant differences due to curing time. Both decreased distance from the tip of the LED light-curing unit and increased curing time increase the surface hardness of nano-filled composite resin. However, curing time increases the surface hardness only if the tip distance is ≤ 5 mm.

  16. Light curing through glass ceramics with a second- and a third-generation LED curing unit: effect of curing mode on the degree of conversion of dual-curing resin cements.

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    Flury, Simon; Lussi, Adrian; Hickel, Reinhard; Ilie, Nicoleta

    2013-12-01

    The aim of this study was to measure the degree of conversion (DC) of five dual-curing resin cements after different curing modes with a second- and a third-generation light-emitting diode (LED) curing unit. Additionally, irradiance of both light curing units was measured at increasing distances and through discs of two glass ceramics for computer-aided design/manufacturing (CAD/CAM). Irradiance and spectra of the Elipar FreeLight 2 (Standard Mode (SM)) and of the VALO light curing unit (High Power Mode (HPM) and Xtra Power Mode (XPM)) were measured with a MARC radiometer. Irradiance was measured at increasing distances (control) and through discs (1.5 to 6 mm thickness) of IPS Empress CAD and IPS e.max CAD. DC of Panavia F2.0, RelyX Unicem 2 Automix, SpeedCEM, BisCem, and BeautiCem SA was measured with an attenuated total reflectance-Fourier transform infrared spectrometer when self-cured (negative control) or light cured in SM for 40 s, HPM for 32 s, or XPM for 18 s. Light curing was performed directly (positive control) or through discs of either 1.5- or 3-mm thickness of IPS Empress CAD or IPS e.max CAD. DC was analysed with Kruskal-Wallis tests followed by pairwise Wilcoxon rank sum tests (α = 0.05). Maximum irradiances were 1,545 mW/cm(2) (SM), 2,179 mW/cm(2) (HPM), and 4,156 mW/cm(2) (XPM), and all irradiances decreased by >80 % through discs of 1.5 mm, ≥95 % through 3 mm, and up to >99 % through 6 mm. Generally, self-curing resulted in the lowest DC. For some cements, direct light curing did not result in higher DC compared to when light cured through ceramic discs. For other cements, light curing through ceramic discs of 3 mm generally reduced DC. Light curing was favourable for dual-curing cements. Some cements were more susceptible to variations in curing mode than others. When light curing a given cement, the higher irradiances of the third-generation LED curing unit resulted in similar DC compared to the second-generation one, though at shorter

  17. Effects of light intensity and curing time of the newest LED Curing units on the diametral tensile strength of microhybrid composite resins

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    Ariani, D.; Herda, E.; Eriwati, Y. K.

    2017-08-01

    The aim of this study was to evaluate the influence of light intensity and curing time of the latest LED curing units on the diametral tensile strength of microhybrid composite resins. Sixty-three specimens from three brands (Polofil Supra, Filtek Z250, and Solare X) were divided into two test groups and one control group. The test groups were polymerized with a Flashmax P3 LED curing unit for one or three seconds. The control group was polymerized with a Ledmax 450 curing unit with the curing time based on the resin manufacturer’s instructions. A higher light intensity and shorter curing time did not influence the diametral tensile strength of microhybrid composite resins.

  18. Curing light burns.

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    Spranley, Thomas J; Winkler, Mark; Dagate, John; Oncale, David; Strother, Elizabeth

    2012-01-01

    This study sought to reveal the potential heat generated by a light-emitting diode (LED) curing light, which has generally been considered to be relatively cool. It is likely that similarly designed curing lights will produce a similar level of heat and have the potential to cause damage to soft tissue.

  19. Evaluation of shear bond strength of orthodontic brackets using trans-illumination technique with different curing profiles of LED light-curing unit in posterior teeth.

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    Heravi, Farzin; Moazzami, Saied Mostafa; Ghaffari, Negin; Jalayer, Javad; Bozorgnia, Yasaman

    2013-11-21

    Although using light-cured composites for bonding orthodontic brackets has become increasingly popular, curing light cannot penetrate the metallic bulk of brackets and polymerization of composites is limited to the edges. Limited access and poor direct sight may be a problem in the posterior teeth. Meanwhile, effectiveness of the trans-illumination technique is questionable due to increased bucco-lingual thickness of the posterior teeth. Light-emitting diode (LED) light-curing units cause less temperature rise and lower risk to the pulpal tissue. The purpose of this study was to evaluate the clinical effectiveness of trans-illumination technique in bonding metallic brackets to premolars, using different light intensities and curing times of an LED light-curing unit. Sixty premolars were randomly divided into six groups. Bonding of brackets was done with 40- and 80-s light curing from the buccal or lingual aspect with different intensities. Shear bond strengths of brackets were measured using a universal testing machine. Data were analyzed by one-way analysis of variance test and Duncan's post hoc test. The highest shear bond belonged to group 2 (high intensity, 40 s, buccal) and the lowest belonged to group 3 (low intensity, 40 s, lingual). Bond strength means in control groups were significantly higher than those in experimental groups. In all experimental groups except group 6 (80 s, high intensity, lingual), shear bond strength was below the clinically accepted values. In clinical limitations where light curing from the same side of the bracket is not possible, doubling the curing time and increasing the light intensity during trans-illumination are recommended for achieving acceptable bond strengths.

  20. Comparison of Bond Strength of Metal and Ceramic Brackets Bonded with Conventional and High-Power LED Light Curing Units

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    Javad Chalipa

    2017-01-01

    Full Text Available Objectives: The aim of this study was to evaluate the effect of conventional and high-power light emitting diode (LED light curing units on shear bond strength (SBS of metal and ceramic brackets to tooth surface.Materials and Methods: Forty sound bovine maxillary central incisors were used for the study. The teeth were divided into four groups (n=10. Teeth surfaces were etched with 37% phosphoric acid for 20 seconds. After applying a uniform layer of adhesive primer on the etched enamel, composite was placed on the base of brackets. The samples were light cured according to the manufacturer’s instructions and thermocycled. The SBS was measured. The failure mode was scored using the adhesive remnant index (ARI.Results: The mean SBS of samples in groups A (high-power LED, metal bracket, B (high-power LED, ceramic bracket, C (conventional LED, metal bracket and D (conventional LED, ceramic bracket was 23.1±3.69, 10.7±2.06, 24.92±6.37 and 10.74±3.18MPa, respectively. The interaction effect of type of LED unit (high-power/conventional and bracket type on SBS was not statistically significant (P=0.483. In general, type of LED unit did not affect SBS. Type of bracket significantly affected SBS (P<0.001. The ARI score was not significantly influenced by the interaction between the type of LED unit and bracket. Conclusions: The obtained SBS is the same for both bracket types by use of high-power and conventional LED light curing units. Regardless of the type of LED unit, SBS of ceramic brackets was significantly lower than that of metal brackets.Keywords: Orthodontic Brackets; Shear Strength; Light-Curing of Dental Adhesives

  1. Advances in light-curing units: four generations of LED lights and clinical implications for optimizing their use: Part 2. From present to future.

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    Shortall, Adrian C; Palin, Will M; Jacquot, Bruno; Pelissier, Bruno

    2012-01-01

    The first part of this series of two described the history of light curing in dentistry and developments in LED lights since their introduction over 20 years ago. Current second- and third-generation LED light units have progressively replaced their halogen lamp predecessors because of their inherent advantages. The background to this, together with the clinical issues relating to light curing and the possible solutions, are outlined in the second part of this article. Finally, the innovative features of what may be seen as the first of a new fourth-generation of LED lights are described and guidance is given for the practitioner on what factors to consider when seeking to purchase a new LED light activation unit. Adequate curing in depth is fundamental to clinical success with any light-activated restoration. To achieve this goal predictably, an appropriate light source needs to be combined with materials knowledge, requisite clinical skills and attention to detail throughout the entire restoration process. As dentists increasingly use light-cured direct composites to restore large posterior restorations they need to appreciate the issues central to effective and efficient light curing and to know what to look for when seeking to purchase a new light-curing unit.

  2. Compressive strength differences between hybrid composites using post curing light box with LED and dry heating, in vitro

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    Jenny Krisnawaty

    2011-11-01

    Full Text Available A hybrid type of composite resins is used as dental restorative materials in a wide cavity directly or indirectly. The mechanical properties of the composite resin would increase post-curing. The purpose of this study was to determine the differences between the compressive strength of hybrid type composite resin post-curing using LED light box and dry heating. This type of research was a quasi-experimental in vitro with the sample size of 30 samples which were divided into two groups. Each sample was tested using a Universal Testing Machine (Lloyd at a speed of 1 mm/minute to test the compressive strength. Compressive strength values were recorded when the sample broke. The average value of compressive strength of the two treatment groups was statistically calculated using t-test. The results, of this study, showed that a hybrid composite resin with post curing using a light box with LED was at 194.138 Mpa which was lower than using the dry heat of 227.339 Mpa. It showed the statistically significant difference. The conclusion of this study was that the compressive strength of post-cured hybrid composites using a light box with LED was significantly lower than the post-curing using dry heat.

  3. Comparison of Bond Strength of Metal and Ceramic Brackets Bonded with Conventional and High-Power LED Light Curing Units.

    Science.gov (United States)

    Chalipa, Javad; Jalali, Yasamin Farajzadeh; Gorjizadeh, Fatemeh; Baghaeian, Pedram; Hoseini, Mohammad Hashem; Mortezai, Omid

    2016-11-01

    The aim of this study was to evaluate the effect of conventional and high-power light emitting diode (LED) light curing units on shear bond strength (SBS) of metal and ceramic brackets to tooth surface. Forty sound bovine maxillary central incisors were used for the study. The teeth were divided into four groups (n=10). Teeth surfaces were etched with 37% phosphoric acid for 20 seconds. After applying a uniform layer of adhesive primer on the etched enamel, composite was placed on the base of brackets. The samples were light cured according to the manufacturer's instructions and thermocycled. The SBS was measured. The failure mode was scored using the adhesive remnant index (ARI). The mean SBS of samples in groups A (high-power LED, metal bracket), B (high-power LED, ceramic bracket), C (conventional LED, metal bracket) and D (conventional LED, ceramic bracket) was 23.1±3.69, 10.7±2.06, 24.92±6.37 and 10.74±3.18MPa, respectively. The interaction effect of type of LED unit (high-power/conventional) and bracket type on SBS was not statistically significant (P=0.483). In general, type of LED unit did not affect SBS. Type of bracket significantly affected SBS (Punit and bracket. The obtained SBS is the same for both bracket types by use of high-power and conventional LED light curing units. Regardless of the type of LED unit, SBS of ceramic brackets was significantly lower than that of metal brackets.

  4. Compressive strength measurements of hybrid dental composites treated with dry heat and light emitting diodes (LED post cure treatment

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    Jenny Krisnawaty

    2014-11-01

    Full Text Available Hybrid composites are mostly used on large cavities as restorative dental materials, whether it is used directly or indirectly. The mechanical properties of composite resin shall increase if it is treated with post cure treatment. The aim of this study is to evaluate compressive strength differences between dry heat and Light Emitting Diodes (LED treatment on the hybrid dental composite. A quasi-experimental was applied on this research with a total of 30 samples that were divided into two groups. Each sample was tested using LLOYD Universal Testing Machine with 1 mm/min speed to evaluate the compressive strength. The compressive strength results were marked when the sample was broken. The results of two groups were then analyzed using t-test statistical calculation. The results of this study show that post cure treatment on hybrid composite using LED light box (194.138 MPa was lower than dry heat treatment (227.339 MPa, which was also significantly different from statistical analysis. It can be concluded that compressive strength of LED light box was lower than dry heat post-cure treatment on the hybrid composite resin.

  5. Robust spectrometer-based methods for characterizing radiant exitance of dental LED light curing units.

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    Shortall, Adrian C; Felix, Christopher J; Watts, David C

    2015-04-01

    Firstly, to assess light output, from a representative range of dental light curing units (LCUs), using a new portable spectrometer based instrument (checkMARC™) compared with a "gold standard" method. Secondly, to assess possible inconsistency between light output measurements using three different laboratory-grade thermopile instruments. The output of four blue-dental LCUs and four polywave blue-and-violet-LCUs was measured with two spectrometer-based systems: a portable spectrometer instrument and a benchtop Integrating Sphere fiber-coupled spectrometer system. Power output was also recorded with three thermopiles according to ISO 10650-2. Beam profile images were recorded of LCU output to assess for spatial and spectral beam uniformity. Power recorded with the portable spectrometer instrument closely matched the 'gold standard' Integrating Sphere apparatus calibrated according to International Standards. Radiant exitance for the eight LCUs differed significantly between the three thermopiles. Light source to thermopile sensor distance influenced recorded power significantly (pSpectrometer-based methods are capable of overcoming the limitations inherent with thermopile-based measurement techniques. Spectrometer based measurements can fulfill the intention of ISO 10650. Copyright © 2015 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  6. Comparison of Surface Hardness of Various Shades of Twinky Star Colored Compomer Light-cured with QTH and LED Units

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    Khodadadi, Effat; Khafri, Soraya; Aziznezhad, Mahdiyeh

    2016-01-01

    Introduction Colored compomers are a group of restorative materials that were introduced in 2002 to repair primary teeth, and they provide attractive color and ease of use in pediatric dentistry. The aim of this study was to evaluate the effect of QTH and LED light-curing units on the surface hardness of different colors of Twinky Star compomers. Methods In this experimental study, a composite resin (Z250, 3M, and USA), an ionosit compomer (DMG, Germany) with A3 shade and 8 different Twinky Star colored compomer (Voco, Germany) samples were used. In all, 100 samples were prepared with 10 samples in each group, i.e., 10 Z250 composite resin, 10 ionosit compomers, and 10 Twinky Star compomer samples of each color. The samples were prepared in a 4×4-mm Teflon mold. Half of the samples were light-cured with QTH and the other half with LED units. Then, the surface microhardness was measured by Vickers hardness test. The data were analyzed with IBM-SPSS version 22, using the t-test and ANOVA. Results Two-way ANOVA showed that the mean surface hardness of the compomer samples cured with the QTH unit was significantly higher than that cured with the LED unit (p curing unit, surface hardness of some materials exhibited significant differences with the highest hardness being observed in the Z250 composite resin (650.35 ± 56.320) and the lowest hardness being detected in the ionosit compomers (461.10 ± 96.170). One-way ANOVA also showed that, among the different colors of the Twinky Star compomer, the lowest hardness with both units (QTH and LED) was observed in the gold color (214.32 ± 22.026 and 175.116 ± 15.918, respectively). Conclusion The colored compomer and the type of light-curing unit affected the microhardnesses of the surfaces. Different colors of Twinky Star compomers exhibited different surface microhardnesses. PMID:27382444

  7. Characterization and optimization of an inkjet-printed smart textile UV-sensor cured with UV-LED light

    Science.gov (United States)

    Seipel, S.; Yu, J.; Periyasamy, A. P.; Viková, M.; Vik, M.; Nierstrasz, V. A.

    2017-10-01

    For the development of niche products like smart textiles and other functional high-end products, resource-saving production processes are needed. Niche products only require small batches, which makes their production with traditional textile production techniques time-consuming and costly. To achieve a profitable production, as well as to further foster innovation, flexible and integrated production techniques are a requirement. Both digital inkjet printing and UV-light curing contribute to a flexible, resource-efficient, energy-saving and therewith economic production of smart textiles. In this article, a smart textile UV-sensor is printed using a piezoelectric drop-on-demand printhead and cured with a UV-LED lamp. The UVcurable ink system is based on free radical polymerization and the integrated UVsensing material is a photochromic dye, Reversacol Ruby Red. The combination of two photoactive compounds, for which UV-light is both the curer and the activator, challenges two processes: polymer crosslinking of the resin and color performance of the photochromic dye. Differential scanning calorimetry (DSC) is used to characterize the curing efficiency of the prints. Color measurements are made to determine the influence of degree of polymer crosslinking on the developed color intensities, as well as coloration and decoloration rates of the photochromic prints. Optimized functionality of the textile UV-sensor is found using different belt speeds and lamp intensities during the curing process.

  8. Comparative evaluation of the effect of Light Emitting Diode (LED and Quartz Tungsten Halogen (QTH light curing units on color stability of Filtek Z350 XT

    Directory of Open Access Journals (Sweden)

    Behnaz Esmaeili

    2014-03-01

    Full Text Available Introduction:Discoloration of the resin-based composites is a common problem in restorative dentistry. There are many factors associated with the discoloration of dental materials in the oral environment. The purpose of this study was to evaluate the color changes in a nano-composite cured with a quartz-tungsten-halogen (QTH and light emitting diode (LED unit. Methods:80 disk-shaped specimens were prepared using Filtek Z350 XT.The specimens were cured with two LED units (Valo and BluephaseC5 and QTH Astralis7 ( with two different energy density (400 & 750 mW/Cm². The color of the materials was measured before and after immersing in tea and artificial saliva. Color change value (ΔE were calculated and analyzed by 2-way ANOVA and Tukey’s test. Results: In artificial saliva group, the composites cured with Astralis7 and BluephaseC5 showed significantly more color stability. In tea group, the composites cured with BluephaseC5 significantly had the least color change. Conclusions: The type of light curing unit does not affect the color stability. Exposure time and interaction between light source and photo initiator content in composite may be the most important factors affecting color stability.

  9. Evaluation of temperature changes in the pulp chamber during polymerization of light-cured pulp-capping materials by using a VALO LED light curing unit at different curing distances.

    Science.gov (United States)

    Savas, Selcuk; Botsali, Murat S; Kucukyilmaz, Ebru; Sari, Tugrul

    2014-01-01

    The aim of this study was to evaluate temperature changes in the pulp chamber during polymerization of four different pulp-capping materials using a LED-light-curing-unit in the contact and noncontact positions. A pulpal circulation mechanism was simulated to measure increases in temperature in four pulp-capping materials that were applied to the occlusal dentin surface. Two different distances were used between the tip of the unit and the material surface during polymerization; 0 and 2 mm. The data were statistically analyzed using factorial-ANOVA, one-way-ANOVA, and Tukey's HSD test. There were statistically differences between contact and noncontact groups (plight curing units from restorations should not be overlooked as well as the types of the materials.

  10. Degree of conversion and temperature increase of a composite resin light cured with an argon laser and blue LED

    Science.gov (United States)

    Rastelli, A. N. S.; Jacomassi, D. P.; Bagnato, V. S.

    2008-12-01

    Different light sources and power densities used on the photoactivation process may provide changes in the degree of conversion (DC%) and temperature ( T) of the composite resins. Thus, the purpose of this study was to evaluate the DC (%) and T (°C) of the microhybrid composite resin (Filtek™ Z-250, 3M/ESPE) photoactivated with one argon laser and one LED (light-emitting diode) with different power densities. For the KBr pellet technique, the composite resin was placed into a metallic mould (2-mm thickness, 4-mm diameter) and photoactivated as follows: a continuous argon laser (CW) and LED LCUs with power density values of 100, 400, 700, and 1000 mW/cm2 for 20 s. The measurements for DC (%) were made in a FTIR spectrometer Bomen (model MB 102, Quebec, Canada). Spectroscopy (FTIR) spectra for both uncured and cured samples were analyzed using an accessory of the reflectance diffusion. The measurements were recorded in absorbance operating under the following conditions: 32 scans, 4 cm-1 resolution, 300 to 4000-cm-1 wavelength. The percentage of unreacted carbon double bonds (% C=C) was determined from the ratio of absorbance intensities of aliphatic C=C (peak at 1638 cm-1) against an internal standard before and after the curing of the specimen: aromatic C-C (peak at 1608 cm-1). For T (°C), the samples were created in a metallic mould (2-mm thickness, 4-mm diameter) and photoactivated for 20 s. The thermocouple was attached to the multimeter allowing temperature readings. The DC (%) and T (°C) were submitted to ANOVA and Tukey’s test ( p units.

  11. A comparative study of the effects of QTH and LED light curing units on the surface hardness of colored compomer and Hybrid composites

    Directory of Open Access Journals (Sweden)

    Effat khodadadi

    2015-03-01

    Full Text Available Introduction: One factor affecting the degree of polymerization is the type of light-curing device. The aim of this study was to compare the effects of LED and QTH light curing units on the surface hardness of composite and compomer. Materials & Methods: In this experimental study, 30 samples of composite and compomer were divided into 3 groups of 10 each. One-half of the subgroups in each group were cured with LED and the other half with Halogen light curing units (LCUs. 49 points on the surface were marked and then the hardness of these points was measured by using Vickers hardness test. Results : The mean hardness of composites cured by using LED was more than the Halogen group but in compomer it was reversed and this difference was statistically significant (p<0.001. Z 250 composite had the highest level of hardness and the lowest hardness was related to the Heliomolar composite and had significant difference. (p<0.001  Conclusion :In the present study, the results indicated that LED light curing unit had great effect on the hardness of composites but in compomer, the QTH showed a better result.

  12. Comparison of the Amount of Temperature Rise in the Pulp Chamber of Teeth Treated With QTH, Second and Third Generation LED Light Curing Units: An In Vitro Study.

    Science.gov (United States)

    Mahant, Rajesh Harivadanbhai; Chokshi, Shraddha; Vaidya, Rupal; Patel, Pruthvi; Vora, Asima; Mahant, Priyanka

    2016-01-01

    Introduction: This in vitro study was designed to measure and compare the amount of temperature rise in the pulp chamber of the teeth exposed to different light curing units (LCU), which are being used for curing composite restorations. Methods: The study was performed in two settings; first, an in vitro and second was mimicking an in vivo situation. In the first setup of the study, three groups were formed according to the respective three light curing sources. i.e. quartz-tungsten-halogen (QTH) unit and two light-emitting diode (LED) units (second and third generations). In the in vitro setting, direct thermal emission from three light sources at 3 mm and 6 mm distances, was measured with a k-type thermocouple, and connected to a digital thermometer. For a simulation of an in vivo situation, 30 premolar teeth were used. Class I Occlusal cavity of all the teeth were prepared and they were restored with incremental curing of composite, after bonding agent application. While curing the bonding agent and composite in layers, the intrapulpal temperature rise was simultaneously measured with a k-type thermocouple. Results: The first setting of the study showed that the heat produced by irradiation with LCU was significantly less at 6 mm distance when compared to 3 mm distance. The second setting of the study showed that the rise of intrapulpal temperature was significantly less with third generation LED light cure units than with second generation LED and QTH light cure units. Conclusion: As the distance from the light source increases, less irradiation heat is produced. Third generation LED lights cause the least temperature change in the pulp chamber of single rooted teeth.

  13. Analysis of temperature increase in swine gingiva after exposure to a Polywave®LED light curing unit.

    Science.gov (United States)

    Maucoski, Cristiane; Zarpellon, Driellen Christine; Dos Santos, Fabio Andre; Lipinski, Leandro Cavalcante; Campagnoli, Eduardo Bauml; Rueggeberg, Frederick Allen; Arrais, Cesar Augusto Galvão

    2017-11-01

    This study evaluated the temperature increase in swine gingival temperature after exposure to light emitted by a Polywave ® LED light curing unit (LCU, Bluephase 20i, Ivoclar Vivadent). After local Ethics Committee approval (protocol 711/2015), 40 pigs were subjected to general anesthesia and the LCU tip was placed 5mm from the buccal gingival tissue (GT) close to lower lateral incisors. A thermocouple probe (Thermes WFI, Physitemp) was inserted into the gingival sulcus before and immediately after exposure to light. Real-time temperature (°C) was measured after the following exposure modes were applied: High Power (20s-H, 40s-H, and 60s-H) or Turbo mode (5s-T), either with or without the presence of rubber dam (RD) interposed between the LCU tip and GT (n=10). The presence of gingival lesions after the exposures was also evaluated. Peak temperature (°C) and the temperature increase during exposure over that of the pre-exposure baseline value (ΔT) data were analyzed using 2-way ANOVA followed by Bonferroni's post-hoc test (α=5%). A binary logistic regression analysis determined the risk of gingival lesion development. Without RD, no significant difference in ΔT was observed among 20s-H, 40s-H, and 60s-H groups, which showed the highest temperature values, while the 5s-T exposure showed the lowest ΔT, regardless of RD. RD reduced ΔT only for the 20s-H group (p=0.004). Gingival lesions were predominantly observed using 40s-H, with RD, and 60s-H, with and without RD. Exposure to a LCU light might be harmful to swine gingiva only when high radiant exposure values are delivered, regardless of the use of RD. Copyright © 2017 The Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  14. An in vitro evaluation of diametral tensile strength and flexural strength of nanocomposite vs hybrid and minifill composites cured with different light sources (QTH vs LED).

    Science.gov (United States)

    Garapati, Surendra Nath; Priyadarshini; Raturi, Piyush; Shetty, Dinesh; Srikanth, K Venkata

    2013-01-01

    Composites always remained the target of discussion due to lot of controversies around it. Mechanical properties are one of them. With the introduction of new technology and emergence of various composites which combine superior strength and polish retention, nanocomposites have led to a new spark in the dentistry. A recent curing unit LED with various curing modes claims to produce higher degree of conversion. The aim of this study was to evaluate the diametral tensile strength and flexural strength of nanocomposite, hybrid and minifill composites cured with different light sources (QTH vs LED). Seventy-two samples were prepared using different specially fabricated teflon molds, 24 samples of each composite were prepared for the diametral tensile strength (ADA specification no. 27) and the flexural strength (ISO 4049) of the 12 samples, six were cured with LED (Soft Start curing profile) and other six with QTH curing light and tested on a universal testing machine. The nanocomposite had highest diametral tensile strength and flexural strength which were equivalent to the hybrid composite and superior than the minifill composite. With the combination of superior esthetics and other optimized physical properties, this novel nanocomposite system would be useful for all posterior and anterior applications.

  15. In vivo temperature rise in anesthetized human pulp during exposure to a polywave LED light curing unit.

    Science.gov (United States)

    Runnacles, Patrício; Arrais, Cesar Augusto Galvão; Pochapski, Marcia Thais; Dos Santos, Fábio André; Coelho, Ulisses; Gomes, João Carlos; De Goes, Mário Fernando; Gomes, Osnara Maria Mongruel; Rueggeberg, Frederick Allen

    2015-05-01

    This in vivo study evaluated pulp temperature (PT) rise in human premolars during exposure to a light curing unit (LCU) using selected exposure modes (EMs). After local Ethics Committee approval, intact first upper premolars, requiring extraction for orthodontic reasons, from 8 volunteers, received infiltrative and intraligamental anesthesia. The teeth (n=15) were isolated using rubber dam and a minute pulp exposure was attained. A sterile probe from a wireless, NIST-traceable, temperature acquisition system was inserted directly into the coronal pulp chamber, and real time PT (°C) was continuously monitored while the buccal surface was exposed to polywave light from a LED LCU (Bluephase 20i, Ivoclar Vivadent) using selected EMs allowing a 7-min span between each exposure: 10-s either in low (10-s/L) or high (10-s/H); 5-s-turbo (5-s/T); and 60-s-high (60-s/H) intensities. Peak PT values and PT increases from baseline (ΔT) after exposure were subjected to one-way, repeated measures ANOVAs, and Bonferroni's post hoc tests (α=0.05). Linear regression analysis was performed to establish the relationship between applied radiant exposure and ΔT. All EMs produced higher peak PT than the baseline temperature (p<0.001). The 60-s/H mode generated the highest peak PT and ΔT (p<0.001), with some teeth exhibiting ΔT higher than 5.5°C. A significant, positive relationship between applied radiant exposure and ΔT (r(2)=0.916; p<0.001) was noted. Exposing intact, in vivo anesthetized human upper premolars to a polywave LED LCU increases PT, and depending on EM and the tooth, PT increase can be higher than the critical ΔT, thought to be associated with pulpal necrosis. Copyright © 2015 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  16. High Power UV LED Industrial Curing Systems

    Energy Technology Data Exchange (ETDEWEB)

    Karlicek, Robert, F., Jr; Sargent, Robert

    2012-05-14

    UV curing is a green technology that is largely underutilized because UV radiation sources like Hg Lamps are unreliable and difficult to use. High Power UV LEDs are now efficient enough to replace Hg Lamps, and offer significantly improved performance relative to Hg Lamps. In this study, a modular, scalable high power UV LED curing system was designed and tested, performing well in industrial coating evaluations. In order to achieve mechanical form factors similar to commercial Hg Lamp systems, a new patent pending design was employed enabling high irradiance at long working distances. While high power UV LEDs are currently only available at longer UVA wavelengths, rapid progress on UVC LEDs and the development of new formulations designed specifically for use with UV LED sources will converge to drive more rapid adoption of UV curing technology. An assessment of the environmental impact of replacing Hg Lamp systems with UV LED systems was performed. Since UV curing is used in only a small portion of the industrial printing, painting and coating markets, the ease of use of UV LED systems should increase the use of UV curing technology. Even a small penetration of the significant number of industrial applications still using oven curing and drying will lead to significant reductions in energy consumption and reductions in the emission of green house gases and solvent emissions.

  17. Clinical long-term success of contemporary nano-filled resin composites in class I and II restorations cured by LED or halogen light.

    Science.gov (United States)

    Pflaum, Torsten; Kranz, Stefan; Montag, Regina; Güntsch, Arndt; Völpel, Andrea; Mills, Robin; Jandt, Klaus; Sigusch, Bernd

    2017-10-28

    The use of LED light-curing units (LED LCUs) for polymerising resin-based composite restorations has become widespread throughout dentistry. Unfortunately, there is a paucity of clinical longitudinal studies that evaluate the comparative efficacy of LED-based polymerisation in direct posterior composite restorations. The aim of the present study was to investigate the performance of class I and II resin composite restorations for two successful composite restorative materials cured with LED versus halogen LCUs. One hundred restorations were placed using the nano-filled composites Grandio® or Filtek™ Supremé. The following test groups were established: LED-Grandio® n = 23 (LG), LED-Filtek™ Supremé n = 21 (LS). As controls were used: Halogen-Grandio® n = 28 (HG), Halogen-Filtek™ Supremé n = 28 (HS). All restorations were evaluated according to the clinical criteria of the CPM index (C-criteria) at baseline and after 6, 12 and 36 months. After 12 and 36 months, there were no significant differences between restorations polymerised with LED or halogen light. At the end of the study, 97% of the restorations showed sufficient results regardless of the employed LCU or composite. Globally, after 36 months, 56% of all restorations were assessed with code 0 (excellent) and 41% with code 1 (acceptable). In detail, excellent results (code 0) among the criteria surface quality; marginal integrity and marginal discoloration were assigned in 72, 70 and 69%. For the current limitations in the clinical trial design, the results showed that LED-polymerisation is appropriate to ensure clinical success of direct posterior resin composite restorations in a range of 3 years. The choice of LCU has no significant influence on the clinical performance of posterior direct resin composite restorations within 3 years of wear.

  18. A comparative evaluation of curing depth and compressive strength of dental composite cured with halogen light curing unit and blue light emitting diode: an in vitro study.

    Science.gov (United States)

    Kumar, C N Vijaya; Gururaj, M; Paul, Joseph

    2012-11-01

    To evaluate the curing depth and compressive strength of dental composite using halogen light curing unit and light emitting diode light curing unit. Eighty cylindrical composite specimens were prepared using posterior composite P60(3M). Forty specimens, out of which 20 samples (group A) cured with halogen light and 20 samples (group B) cured using light emitting diode (LED) light were checked for curing depth according to ISO 4049. Remaining 40 samples out of which 20 samples (group I) cured using halogen light and 20 samples (group II) cured using LED light were checked for compressive strength using Instron universal testing machine. Twenty samples (group A) cured with halogen light showed better curing depth than 20 samples (group B) cured with LED light. Twenty samples (group I) cured with halogen light showed almost similar results as 20 samples (group II) cured with LED light for compressive strength. Halogen light commonly used to cure composite resin have greater depth of cure, when compared to LED light, while both the lights produced compressive strength which is almost similar. Lower depth of cure with the LED unit, compared to the QTH unit, is associated with different light scattering due to differences in spectral emission. LED technology differs from QTH by the spectral emission that favorably matches the absorption spectrum of camphorquinone.

  19. Degree of conversion of micro-hybrid, nano-hybrid and Ormocer composites using LED and QTH light-curing units

    Directory of Open Access Journals (Sweden)

    Seied Mostafa Fatemi

    2012-01-01

    Full Text Available Background and Aims: The aim of this study was to measure the degree of conversion (DC of three types of composite resins (micro-hybrid, nano-hybrid and Ormocer with different light curing units (LED LCU and QTH LCU in two depths.Materials and Methods: Three commercially available dental resin composites were used in this study: (Tetric Ceram, Ivoclar Vivadent, Liechtenstein-A2 shade, (Tetric Evoceram, Ivoclar Vivadent, Liechtenstein-A2 shade, (Ceram X, Dentsply, Germany-M2 shade. Specimens were divided into two groups, 5 specimens were photo-activated by QTH unit (Coltolux 75-Colten and the other five specimens were cured by LED (Demi-Kerr. Then each specimen was sectioned at the top surface and at 2-mm depth. The DC was measured by FT-IR(Bruker-tensor 27. The data were analyzed by 3-way ANOVA test.Results: There was significant difference between tested composite resins (P<0.001. The results of top surfaces were significantly different from those observed at 2-mm depth (P<0.001. The type of curing unit affected the polymerization of Ceram X resin composite.Conclusion: This study showed a significant difference in the degree of conversion in different thicknesses within three groups of resin composites.

  20. Light Emitting Diode (LED)

    Science.gov (United States)

    1997-01-01

    A special lighting technology was developed for space-based commercial plant growth research on NASA's Space Shuttle. Surgeons have used this technology to treat brain cancer on Earth, in two successful operations. The treatment technique called photodynamic therapy, requires the surgeon to use tiny pinhead-size Light Emitting Diodes (LEDs) (a source releasing long wavelengths of light) to activate light-sensitive, tumor-treating drugs. Laser light has been used for this type of surgery in the past, but the LED light illuminates through all nearby tissues, reaching parts of a tumor that shorter wavelengths of laser light carnot. The new probe is safer because the longer wavelengths of light are cooler than the shorter wavelengths of laser light, making the LED less likely to injure normal brain tissue near the tumor. It can also be used for hours at a time while still remaining cool to the touch. The LED probe consists of 144 tiny pinhead-size diodes, is 9-inches long, and about one-half-inch in diameter. The small balloon aids in even distribution of the light source. The LED light source is compact, about the size of a briefcase, and can be purchased for a fraction of the cost of a laser. The probe was developed for photodynamic cancer therapy by the Marshall Space Flight Center under a NASA Small Business Innovative Research program grant.

  1. Light Emitting Diodes (LEDs)

    Science.gov (United States)

    1997-01-01

    A special lighting technology was developed for space-based commercial plant growth research on NASA's Space Shuttle. Surgeons have used this technology to treat brain cancer on Earth, in two successful operations. The treatment technique, called Photodynamic Therapy, requires the surgeon to use tiny, pinhead-size Light Emitting Diodes (LEDs) (a source that releases long wavelengths of light ) to activate light-sensitive, tumor-treating drugs. 'A young woman operated on in May 1999 has fully recovered with no complications and no evidence of the tumor coming back,' said Dr. Harry Whelan, a pediatric neurologist at the Medical Hospital of Wisconsin in Milwaukee. Laser light has been used for this type of surgery in the past, but the LED light illuminates through all nearby tissues, reaching parts of a tumor that shorter wavelengths of laser light carnot. The new probe is safer because the longer wavelengths of light are cooler than the shorter wavelengths of laser light, making the LED less likely to injure normal brain tissue near the tumor. It can be used for hours at a time while still remaining cool to the touch. The LED light source is compact, about the size of a briefcase, and can be purchased for a fraction of the cost of a laser. The LEDs, developed and managed by NASA's Marshall Space Flight Center, have been used on seven Space Shuttle flights inside the Microgravity Astroculture Facility. This technology has also been successfully used to further commercial research in crop growth.

  2. CURING EFFICIENCY OF DUAL-CURE RESIN CEMENT UNDER ZIRCONIA WITH TWO DIFFERENT LIGHT CURING UNITS

    Directory of Open Access Journals (Sweden)

    Pınar GÜLTEKİN

    2015-04-01

    Full Text Available Purpose: Adequate polymerization is a crucial factor in obtaining optimal physical properties and a satisfying clinical performance from composite resin materials. The aim of this study was to evaluate the polymerization efficiency of dual-cure resin cement cured with two different light curing units under zirconia structures having differing thicknesses. Materials and Methods: 4 zirconia discs framework in 4 mm diameter and in 0.5 mm, 1 mm and 1.5 mm thickness were prepared using computer-aided design system. One of the 0.5 mm-thick substructures was left as mono-layered whereas others were layered with feldspathic porcelain of same thickness and ceramic samples with 4 different thicknesses (0.5, 1, 1.5 and 2.0 mm were prepared. For each group (n=12 resin cement was light cured in polytetrafluoroethylene molds using Light Emitting Diode (LED or Quartz-Tungsten Halogen (QHT light curing units under each of 4 zirconia based discs (n=96. The values of depth of cure (in mm and the Vickers Hardness Number values (VHN were evaluated for each specimen. Results: The use of LED curing unit produced a greater depth of cure compared to QTH under ceramic discs with 0.5 and 1 mm thickness (p<0.05.At 100μm and 300 μm depth, the LED unit produced significantly greater VHN values compared to the QTH unit (p<0.05. At 500 μm depth, the difference between the VHN values of LED and QTH groups were not statistically significant. Conclusion: Light curing may not result in adequate resin cement polymerization under thick zirconia structures. LED light sources should be preferred over QTH for curing dual-cure resin cements, especially for those under thicker zirconia restorations.

  3. Effect of a broad-spectrum LED curing light on the Knoop microhardness of four posterior resin based composites at 2, 4 and 6-mm depths.

    Science.gov (United States)

    ALShaafi, Maan M; Haenel, Thomas; Sullivan, Braden; Labrie, Daniel; Alqahtani, Mohammed Q; Price, Richard B

    2016-02-01

    To measure the Knoop microhardness at the bottom of four posterior resin-based composites (RBCs): Tetric EvoCeram Bulk Fill (Ivoclar Vivadent), SureFil SDR flow (DENTSPLY), SonicFill (Kerr), and x-tra fil (Voco). The RBCs were expressed into metal rings that were 2, 4, or 6-mm thick with a 4-mm internal diameter at 30°C. The uncured specimens were covered by a Mylar strip and a Bluephase 20i (Ivoclar Vivadent) polywave(®) LED light-curing unit was used in high power setting for 20s. The specimens were then removed and placed immediately on a Knoop microhardness-testing device and the microhardness was measured at 9 points across top and bottom surfaces of each specimen. Five specimens were made for each condition. As expected, for each RBC there was no significant difference in the microhardness values at the top of the 2, 4 and 6-mm thick specimens. SureFil SDR Flow was the softest resin, but was the only resin that had no significant difference between the KHN values at the bottom of the 2 and 4-mm (Mixed Model ANOVA pcure was evaluated when determining the depth of cure. SureFil SDR Flow was the softest material and, in accordance with manufacturer's instructions, this RBC should be overlaid with a conventional resin. Copyright © 2015 Elsevier Ltd. All rights reserved.

  4. UV-LED Curing Efficiency of Wood Coatings

    OpenAIRE

    Landry, Véronic; Blanchet, Pierre; Boivin, Gabrielle; Bouffard, Jean-François; Vlad, Mirela

    2015-01-01

    Ultraviolet light emitting diodes (UV-LEDs) have attracted great interest in recent years. They can be used to polymerize coatings, such as those used for prefinished wood flooring. In this project, two lamps were compared for their suitability to be used on a wood flooring finishing line: a UV-microwave and a UV-LED lamp. Low heat emission was found for the UV-LED lamp compared to the UV-microwave one. This study also reveals that the 4 W/cm2 UV-LED lamp used is not powerful enough to cure ...

  5. Curing efficiency of dual-cure resin cement under zirconia with two different light curing units.

    Science.gov (United States)

    Gultekin, Pınar; Pak Tunc, Elif; Ongul, Deger; Turp, Volkan; Bultan, Ozgur; Karataslı, Burcin

    2015-01-01

    Adequate polymerization is a crucial factor in obtaining optimal physical properties and a satisfying clinical performance from composite resin materials. The aim of this study was to evaluate the polymerization efficiency of dual-cure resin cement cured with two different light curing units under zirconia structures having differing thicknesses. 4 zirconia discs framework in 4 mm diameter and in 0.5 mm, 1 mm and 1.5 mm thickness were prepared using computer-aided design system. One of the 0.5 mm-thick substructures was left as mono-layered whereas others were layered with feldspathic porcelain of same thickness and ceramic samples with 4 different thicknesses (0.5, 1, 1.5 and 2.0 mm) were prepared. For each group (n=12) resin cement was light cured in polytetrafluoroethylene molds using Light Emitting Diode (LED) or Quartz-Tungsten Halogen (QHT) light curing units under each of 4 zirconia based discs (n=96). The values of depth of cure (in mm) and the Vickers Hardness Number values (VHN) were evaluated for each specimen. The use of LED curing unit produced a greater depth of cure compared to QTH under ceramic discs with 0.5 and 1 mm thickness (punit produced significantly greater VHN values compared to the QTH unit (pLight curing may not result in adequate resin cement polymerization under thick zirconia structures. LED light sources should be preferred over QTH for curing dual-cure resin cements, especially for those under thicker zirconia restorations.

  6. Hardness Evaluation of Composite Resins Cured with QTH and LED

    Directory of Open Access Journals (Sweden)

    Behnaz Esmaeili

    2014-03-01

    Full Text Available Background and aims. Today light cured composites are widely used. Physical and mechanical properties of composites are related to the degree of conversion. Light curing unit (LCU is an important factor for composite polymerization. Aim of this study is evaluation of composite resins hardness using halogen and LED light curing units. Materials and methods. In this study, 30 samples of Filtek Z250 and C-Fill composite resins were provided. Samples were light cured with Ultralume2, Valo and Astralis7. Vickers hardness number (VHN was measured in 0, 1, 2 mm depth. Statistical analysis used: Data were analysed by SPSS software and compared with each other by T-test, one-way and twoway ANOVA and Post-hoc Tukey test. Results. In Filtek Z250, at top surface, VHN of Ultralume2 was higher than VHN of Valo (P = 0.02 and Astralis7 (P = 0.04, but in depth of 1, 2 mm, VHN of Ultralume2 and Astralis7 were almost the same and both LCUs were more than Valo which the difference between Ultralume2 and Valo was significant in depth of 1mm (0.05 and 2mm (0.02. In C-Fill composite, at top surface, Astralis7 showed higher VHN, but in depth of 2 mm, performance of all devices were rather similar. Conclusion. In Z250, which contains camphorquinone initiator, light cure LED Ultra-lume2 with narrow wavelength showed higher hardness number than Valo. In C-fill, in top surface, Astralis7 with more exposure time, resulted higher VHN. But In depth of 2 mm, various light curing devices had rather similar hardness number.

  7. [LED lights in dermatology].

    Science.gov (United States)

    Noé, C; Pelletier-Aouizerate, M; Cartier, H

    2017-04-01

    The use in dermatology of light-emitting diodes (LEDs) continues to be surrounded by controversy. This is due mainly to poor knowledge of the physicochemical phases of a wide range of devices that are difficult to compare to one another, and also to divergences between irrefutable published evidence either at the level of in vitro studies or at the cellular level, and discordant clinical results in a variety of different indications: rejuvenation, acne, wound healing, leg ulcers, and cutaneous inflammatory or autoimmune processes. Therapeutic LEDs can emit wavelengths ranging from the ultraviolet, through visible light, to the near infrared (247-1300 nm), but only certain bands have so far demonstrated any real value. We feel certain that if this article remains factual, then readers will have a different, or at least more nuanced, opinion concerning the use of such LED devices in dermatology. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

  8. Curing performance of a new-generation light-emitting diode dental curing unit.

    Science.gov (United States)

    Wiggins, Kim M; Hartung, Martin; Althoff, Olaf; Wastian, Christine; Mitra, Sumita B

    2004-10-01

    BACKGROUND; Recent technological advances have resulted in the marketing of high-powered, or HP, battery-operated light-emitting diode, or LED, dental curing lights. The authors examine the curing efficiency and peak polymerization temperature, or Tp, of a new HP LED curing light. The authors studied four visible light-curing, or VLC, units: HP LED (A), first-generation LED (B), conventional halogen (C) and high-intensity halogen (D). They determined the depth of cure, or DOC; adhesion; and Tp of three types of VLC resin-based composites after exposure to each light. The exposure times for units A and D were one-half those for units B and C. The power density of unit A was 1,000 milliwatts per square centimeter, which was comparable to that of unit D with turbo charge. The DOC and adhesion attained for all three resin-based composites after being light cured by unit A for a 10-second exposure time were equivalent to those after being light cured by unit D for a 10-second exposure time and to those after being light cured by units B and C for 20-second exposure times. The resin-based composites light cured by unit A attained significantly lower Tps than did those light cured by unit D at equivalent cure, or exposure, times and by unit C at twice the cure time. The authors found that Unit A effectively cured the resin-based composites at one-half the cure time of units B and C and at the same time as unit D, while maintaining low Tp. The battery-operated HP LED curing light might be an effective, time-saving alternative for clinicians to use in light curing resin-based composites.

  9. Polymerization of a dual-cured cement through ceramic: LED curing light vs halogen lamp Polimerização de um cimento resinoso dual através de uma porcelana: LED vs lâmpada halógena

    Directory of Open Access Journals (Sweden)

    Lawrence Gonzaga Lopes

    2004-12-01

    Full Text Available The aim of this study was to investigate the influence of light source, LED unit and halogen lamp (HL, on the effectiveness of Enforce dual-cured cement cured under a ceramic disc. Three exposure times (60, 80 and 120 s were also evaluated. Two experimental groups, in which the polymerization of the dual-cured cement was performed through a ceramic disc, and two control groups, in which the polymerization of the dual-cured cement was performed directly without presence of ceramic disc were subdivided into three subgroups (three different exposure times, with five specimens each: G1A- HL 60s; G1B- HL 80s; G1C- HL 120s; G2A- LED 60s; G2B- LED 80s; G2C- LED 120s; and control groups: G3A- HL 60s; G3B- HL 80s; G3C- HL 120s; G4A- LED 60s; G4B- LED 80s and G4C- LED 120s. Cement was applied in a steel matrix (4mm diameter, 1.2mm thickness. In the experimental groups, a ceramic disc was placed on top. The cement was light-cured through the ceramic by a HL and LED, however, the control groups were cured without the ceramic disc. The specimens were stored in a light-proof container at 37ºC for 24 hours, then Vickers hardness was determined. A four-way ANOVA and Tukey test (p£ 0.05 were performed. All specimens cured by LED for 60s showed inferior values compared with the halogen groups. In general, light-curing by LED for 80s and 120s was comparable to halogen groups (60s and 80s and their control groups. LED technology can be viable for light-curing through conventional ceramic indirect restorations, when curing time is increased in relation to HL curing time.O objetivo deste estudo foi estudar a influência da fonte de luz, LED e lâmpada halógena (LH, na efetividade de polimerização do cimento resinoso dual Enforce fotoativado sob um disco de porcelana. Três tempos de exposição (60, 80 e 120 segundos foram também avaliados. Dois grupos experimentais, na qual a polimerização do cimento resinoso foi feita através de um disco cerâmico, e dois

  10. Hardening of a dual-cure resin cement using QTH and LED curing units

    Science.gov (United States)

    SANTOS, Maria Jacinta Moraes Coelho; PASSOS, Sheila Pestana; da ENCARNAÇÃO, Monalisa Olga Lessa; SANTOS, Gildo Coelho; BOTTINO, Marco Antonio

    2010-01-01

    Objective This study evaluated the surface hardness of a resin cement (RelyX ARC) photoactivated through indirect composite resin (Cristobal) disks of different thicknesses using either a light-emitting diode (LED) or quartz tungsten halogen (QTH) light source. Material and Methods Eighteen resin cement specimens were prepared and divided into 6 groups according to the type of curing unit and the thickness of resin disks interposed between the cement surface and light source. Three indentations (50 g for 15 s) were performed on the top and bottom surface of each specimen and a mean Vickers hardness number (VHN) was calculated for each specimen. The data were analyzed using two-way ANOVA and Tukey-Kramer test was used for post-hoc pairwise comparisons. Results Increased indirect resin disk thickness resulted in decreased mean VHN values. Mean VHN values for the top surfaces of the resin cement specimens ranged from 23.2 to 46.1 (QTH) and 32.3 to 41.7 (LED). The LED curing light source produced higher hardness values compared to the QTH light source for 2- and 3-mm-thick indirect resin disks. The differences were clinically, but not statistically significant. Increased indirect resin disk thickness also resulted in decreased mean VHN values for the bottom surfaces of the resin cement: 5.8 to 19.1 (QTH) and 7.5 to 32.0 (LED). For the bottom surfaces, a statistically significant interaction was also found between the type of curing light source and the indirect resin disk thickness. Conclusions Mean surface hardness values of resin cement specimens decreased with the increase of indirect resin disk thickness. The LED curing light source generally produced higher surface hardness values. PMID:20485920

  11. Hardening of a dual-cure resin cement using QTH and LED curing units

    Directory of Open Access Journals (Sweden)

    Maria Jacinta Moraes Coelho Santos

    2010-04-01

    Full Text Available OBJECTIVE: This study evaluated the surface hardness of a resin cement (RelyX ARC photoactivated through indirect composite resin (Cristobal disks of different thicknesses using either a light-emitting diode (LED or quartz tungsten halogen (QTH light source. MATERIAL AND METHODS: Eighteen resin cement specimens were prepared and divided into 6 groups according to the type of curing unit and the thickness of resin disks interposed between the cement surface and light source. Three indentations (50 g for 15 s were performed on the top and bottom surface of each specimen and a mean Vickers hardness number (VHN was calculated for each specimen. The data were analyzed using two-way ANOVA and Tukey-Kramer test was used for post-hoc pairwise comparisons. RESULTS: Increased indirect resin disk thickness resulted in decreased mean VHN values. Mean VHN values for the top surfaces of the resin cement specimens ranged from 23.2 to 46.1 (QTH and 32.3 to 41.7 (LED. The LED curing light source produced higher hardness values compared to the QTH light source for 2- and 3-mm-thick indirect resin disks. The differences were clinically, but not statistically significant. Increased indirect resin disk thickness also resulted in decreased mean VHN values for the bottom surfaces of the resin cement: 5.8 to 19.1 (QTH and 7.5 to 32.0 (LED. For the bottom surfaces, a statistically significant interaction was also found between the type of curing light source and the indirect resin disk thickness. CONCLUSION: Mean surface hardness values of resin cement specimens decreased with the increase of indirect resin disk thickness. The LED curing light source generally produced higher surface hardness values.

  12. Light curing through glass ceramics: effect of curing mode on micromechanical properties of dual-curing resin cements.

    Science.gov (United States)

    Flury, Simon; Lussi, Adrian; Hickel, Reinhard; Ilie, Nicoleta

    2014-04-01

    The aim of this study was to investigate micromechanical properties of five dual-curing resin cements after different curing modes including light curing through glass ceramic materials. Vickers hardness (VH) and indentation modulus (Y HU) of Panavia F2.0, RelyX Unicem 2 Automix, SpeedCEM, BisCem, and BeautiCem SA were measured after 1 week of storage (37 °C, 100 % humidity). The resin cements were tested following self-curing or light curing with the second-generation light-emitting diode (LED) curing unit Elipar FreeLight 2 in Standard Mode (1,545 mW/cm(2)) or with the third-generation LED curing unit VALO in High Power Mode (1,869 mW/cm(2)) or in XtraPower Mode (3,505 mW/cm(2)). Light curing was performed directly or through glass ceramic discs of 1.5 or 3 mm thickness of IPS Empress CAD or IPS e.max CAD. VH and Y HU were analysed with Kruskal-Wallis tests followed by pairwise Wilcoxon rank sum tests (α = 0.05). RelyX Unicem 2 Automix resulted in the highest VH and Y HU followed by BeautiCem SA, BisCem, SpeedCEM, and finally Panavia F2.0. Self-curing of RelyX Unicem 2 Automix and SpeedCEM lowered VH and Y HU compared to light curing whereas self-curing of Panavia F2.0, BisCem, and BeautiCem SA led to similar or significantly higher VH and Y HU compared to light curing. Generally, direct light curing resulted in similar or lower VH and Y HU compared to light curing through 1.5-mm-thick ceramic discs. Light curing through 3-mm-thick discs of IPS e.max CAD generally reduced VH and Y HU for all resin cements except SpeedCEM, which was the least affected by light curing through ceramic discs. The resin cements responded heterogeneously to changes in curing mode. The applied irradiances and light curing times adequately cured the resin cements even through 1.5-mm-thick ceramic discs. When light curing resin cements through thick glass ceramic restorations, clinicians should consider to prolong the light curing times even with LED curing units providing high

  13. Comparison of hardness of three temporary filling materials cured by two light-curing devices.

    Science.gov (United States)

    Bodrumlu, E; Koçak, M M; Hazar Bodrumlu, E; Ozcan, S; Koçak, S

    2014-01-01

    Polymerization ability of light-curing devices can affect the light-cured material hardness. The purpose of the present study was to evaluate and compare the hardness of three temporary filling materials that had been light-cured by either a light emitting diode (LED) or a halogen light-curing unit. The temporary filling materials, First Fill, Voco Clip and Bioplic, were placed in wells in a Teflon plate. The 24 specimens of each material were divided into two groups (N.=12/group) for photo-activation by either of the two light-curing units. The LED or halogen device was applied for 40s to the top surface of each specimen. A Knoop hardness test was performed on the top and bottom surface of each specimen, with five measurements per specimen. The highest hardness values for both the LED and halogen treated groups were observed for First Fill and the lowest values were for Voco Clip in top and bottom surfaces. The hardness obtained for the three materials with the halogen unit were significantly higher than the values obtained with the LED unit in both surfaces (Plight-cured temporary material exhibited the highest hardness values on the top and bottom surfaces than Voco Clip and Bioplic temporary materials. The hardness of light-cured temporary filling materials can be affected by the type of light-curing unit.

  14. Influence of Curing-light Unit and Exposure Conditions on the Properties of Lightcured Resin Composite on Curing-light Units

    OpenAIRE

    岡田, 英俊; 石田, 喜紀; 野口, 博志; 長山, 克也; オカダ, ヒデトシ; イシダ, ヨシキ; ノグチ, ヒロシ; ナガヤマ, カツヤ; Hidetoshi, OKADA; Yoshiki, ISHIDA; Hiroshi, NOGUCHI; Katsuya, NAGAYAMA

    2003-01-01

    The purpose of this study was to examine the influence of curing light units and exposure conditions on the prperties of the polymerization of a lightcured resin composite. Lightfil was used as a resin composite. The curing light units used were a JETLITE, as a halogen lamp curing light source (HAL), a MICROWAVE, as a xenon lamp curing light source (XEN), and a AQUABLUE, as a light-emitting diode curing light source (LED). Each curing light unit was used to cure the resin composite with the i...

  15. Efficiency of dual-cured resin cement polymerization induced by high-intensity LED curing units through ceramic material.

    Science.gov (United States)

    Watanabe, H; Kazama, Re; Asai, T; Kanaya, F; Ishizaki, H; Fukushima, M; Okiji, T

    2015-01-01

    This study aimed to evaluate the ability of high-intensity light-emitting diode (LED) and other curing units to cure dual-cured resin cement through ceramic material. A halogen curing unit (Jetlite 3000, Morita), a second-generation LED curing unit (Demi, Kerr), and two high-intensity LED curing units (PenCure 2000, Morita; Valo, Ultradent) were tested. Feldspathic ceramic plates (VITABLOCS Mark II, A3; Vita Zahnfabrik) with thicknesses of 1.0, 2.0, and 3.0 mm were prepared. Dual-cured resin cement samples (Clearfil Esthetic Cement, Kuraray Noritake Dental) were irradiated directly or through one of the ceramic plates for different periods (5, 10, 15, or 20 seconds for the high-intensity LED units and 20, 40, 60, or 80 seconds for the others). The Knoop hardness test was used to determine the level of photopolymerization that had been induced in the resin cement. Data were analyzed by one-way analysis of variance and Dunnett's post-hoc test to identify test-control (maximum irradiation without a ceramic plate) differences for each curing unit (presin cement through a ceramic plate resulted in decreased KHN values compared with direct irradiation. When the irradiation period was extended, only the LED units were able to achieve similar KHN values to those observed under direct irradiation in the presence of plates ≥2.0-mm thick. High-intensity LED units require a shorter irradiation period than halogen and second-generation LED curing units to obtain KHN values similar to those observed during direct irradiation.

  16. Comparação da influência entre tempos de polimerização em resinas compostas polimerizadas com LED e Luz Incandescente Comparison of the influence of curing times applied to composite resins cured with LED and Incandescent Light

    Directory of Open Access Journals (Sweden)

    Michele P. M. Ulhoa

    2007-09-01

    Full Text Available O propósito deste trabalho é fazer uma comparação entre resinas poliméricas dentárias, polimerizadas por aparelhos baseados em lâmpada halógena e diodo emissor de Luz (LED, utilizando-se o método do disco retificado aperfeiçoado para odontologia e os respectivos valores de microdureza. Foram realizados testes em amostras de resinas compostas de 5 diferentes marcas, polimerizadas a tempos de 10, 20 e 40 s, pelos dois aparelhos. A análise estatística dos valores de microdureza e agressividade permitiu concluir que estatisticamente não há correlação entre essas propriedades. Na análise de microdureza, a heterogeneidade característica do material implicou em resultados com valores de desvio padrão relativamente altos, de forma que não foi encontrada diferença estatística entre as amostras avaliadas. Na análise estatística dos ensaios baseados no método do disco retificado, a resina que apresentou maior desgaste nos ensaios, foi a Tetric Ceram, polimerizada pelo aparelho de LED por 10 s, cujo valor médio de agressividade obtido foi 0,170 mm³/N.m. A resina que sofreu menor desgaste foi a Charisma, polimerizada por Lâmpada Incandescente, por um tempo de 20 s, cuja média dos valores de agressividade foi 0,057 mm³/N.m.The purpose of this work was to compare polymeric dental resins cured with halogen lamp and with light emission diode (LED devices, using the grinding disk method customized for dentistry and the corresponding microhardness values. Tests were carried out on resin samples of five brands, which were cured for 10, 20 and 40 s with the two devices. The analysis of microhardness and aggressiveness has allowed us to conclude that there is no correlation between these properties. In Microhardness tests, the material heterogeneity has produced relative high standard deviation values and has not shown statistical differences between the analyzed samples. In the statistical analysis for the results with the grinding disk

  17. Vickers Hardness of Composite Resins Cured with LED and QTH Units

    Directory of Open Access Journals (Sweden)

    Alaghemand H

    2016-03-01

    Full Text Available Statement of Problem: One of the factors affecting the degree of polymerization of light-cured composites is the type of light-curing unit used. In addition, physicomechanical properties of the composite resins depend on the degree of conversion and polymerization. Objectives: Since the type of initiator in new composite resins is not explained by manufacturers, this study is an attempt to compare the depth of hardening, with two LED and QTH light-curing units. Materials and Methods: Fifteen samples prepared from Gradia Direct and Filtek Z250, both of which being universal, were cured with QTH (Astralis 7 and LED (Bluephase C8 light-curing units. All the samples were molded in polyester resin and cut from the middle by a disk. The hardness of the cut area was evaluated at 0, 0.5, 1, 1.5, 2, 2.5, 3, 3.5 and 4-mm depth intervals and also at the same interval as the width of the sample, with Vickers hardness machine, while the samples were placed in a darkroom. Data were statistically analyzed using one-way ANOVA, two-way ANOVA, t-test and post Hoc Tukey’s tests in SPSS, version 16. Results: Filtek Z250 was harder than Gradia Direct at all the depth with both light-curing units. The hardness of Filtek Z250 sample cured with Astralis 7 was higher than that cured with LED, but with Gradia Direct the LED unit resulted in higher hardness. Curing depth was not significantly different between the groups (p = 0.109. Conclusions: Vickers hardness number for both composites used in this study is in an acceptable range for clinical implications. The composites’ composition is important to be considered for selection of light unit. Based on the findings of the present study, LED did not present more curing depth compared with QTH.

  18. Effectiveness of composite resin polymerization using light-emitting diodes (LEDs or halogen-based light-curing units Efetividade de polimerização de uma resina composta fotopolimerizada por diodos emissores de luz (LEDs ou luz halógena

    Directory of Open Access Journals (Sweden)

    Bianca Micali

    2004-09-01

    Full Text Available The clinical performance of composite resins is greatly influenced by the quality of the light-curing unit used. The aim of this study was to compare the efficiency of a commercial light-emitting diode (LED with that of a halogen-based light-curing unit by means of dye penetration of a micro hybrid composite resin. The composite resin evaluated was Filtek Z250 (3M Dental. The composite was filled into acrylic moulds that were randomly polymerized for 40 seconds by each of the light-emitting systems: light-emitting diode Ultraled (Dabi Atlante or halogen light Degulux (Degussa Hüls curing units. Immediately after polymerization, each specimen was individually immersed in 1 ml of 2% methylene blue solution at 37°C ± 2°C. After 24 hours, the specimens were rinsed under running distilled water for 1 minute and stored at 37°C ± 2°C at relative humidity for 24 hours. The composite resins were removed from the moulds and individually triturated before being immersed in new test tubes containing 1 ml of absolute alcohol for 24 hours. The solutions were filtered and centrifuged for 3 minutes at 4,000 rpm and the supernatant was used to determine absorbance in a spectrophotometer at 590 nm. To verify the differences between groups polymerized by LED or halogen light t-test was applied. No significant differences were found between composite resins light-cured by LED or halogen light-curing unit (p > 0.05. The commercially LED-based light-curing unit is as effective to polymerize hybrid composite resins as the halogen-based unit.A longevidade clínica das resinas compostas é grandemente influenciada pela qualidade do aparelho fotopolimerizador utilizado. O objetivo deste trabalho foi comparar a eficácia de um aparelho fotopolimerizador de diodos emissores de luz e a de um de luz halógena através do grau de penetração de um corante em uma resina composta micro-híbrida. A resina composta utilizada (Filtek Z250/3M Dental foi inserida em matrizes

  19. Light output from six battery operated dental curing lights.

    Science.gov (United States)

    Shimokawa, Carlos Alberto Kenji; Turbino, Míriam Lacalle; Harlow, Jessie Eudora; Price, Hannah Louise; Price, Richard Bengt

    2016-12-01

    Light Curing Units (LCUs) are used daily in almost every dental office to photocure resins, but because the light is so bright, the user is unable to tell visually if there are any differences between different LCUs. This study evaluated the light output from six dental LCUs: Elipar Deep Cure-S (3M ESPE), Bluephase G2 (Ivoclar Vivadent), Translux 2Wave (Heraeus Kulzer), Optilight Prime (Gnatus), Slim Blast (First Medica) and Led.B (Guilin Woodpecker) with a fully charged battery, after 50, and again after 100, 20second light exposures. For each situation, the radiant power was measured 10 times with a laboratory-grade power meter. Then, the emission spectrum was measured using a fiber-optic spectrometer followed by an analysis of the light beam profile. It was found there were significant differences in the LCU power and the irradiance values between the LCUs (p<0.01). The Optilight Prime and Slim Blast LCUs showed a significant reduction in light output after a 50 and 100 exposures, while Bluephase G2 exhibited a significant reduction only after 100 exposures (p<0.01). The Bluephase G2 and Translux 2Wave delivered an emission spectrum that had two distinct wavelength emission peaks. Only the Elipar Deep Cure-S and Bluephase G2 LCUs displayed homogeneous light beam profiles, the other LCUs exhibited highly non-homogeneous light beam profiles. It was concluded that contemporary LCUs could have very different light output characteristics. Both manufacturers and researchers should provide more information about the light output from LCUs. Copyright © 2016 Elsevier B.V. All rights reserved.

  20. Comparison of the heat generation of light curing units.

    Science.gov (United States)

    Bagis, Bora; Bagis, Yildirim; Ertas, Ertan; Ustaomer, Seda

    2008-02-01

    The aim of this study was to evaluate the heat generation of three different types of light curing units. Temperature increases were recorded from a distance of 1 mm from a thermocouple to the tip of three different types of light curing units including one quartz-tungsten halogen (QTH), one plasma arc (PAC), and one light emitting diode (LED) unit. An experimental model was designed to fix the 1 mm distance between the tip of the light curing units and the thermocouple wire. Temperature changes were recorded in 10 second intervals up to 40 seconds. (10, 20, 30, and 40 seconds). Temperature measurements were repeated three times for every light curing unit after a one hour standby period. Statistical analysis of the results was performed using the analysis of variance (ANOVA) and the Bonferroni Test. The highest temperature rises (54.4+/-1.65 degrees C) occurred during activation of a PAC light curing unit for every test period (p<.05). The least temperature increase (11.8+/-1.3 degrees C) occurred with a LED curing unit for each tested period except for the measurement of the temperature rise using the QTH curing unit at the tenth second interval (p<.05). These results indicate the choice of light activation unit and curing time is important when polymerizing light activated resin based restorations to avoid any thermal damage to the pulp.

  1. Light pipes for LED measurements

    Science.gov (United States)

    Floyd, S. R.; Thomas, E. F., Jr.

    1976-01-01

    Light pipe directly couples LED optical output to single detector. Small area detector measures total optical output of diode. Technique eliminates thermal measurement problems and channels optical output to remote detector.

  2. Practical lighting design with LEDs

    CERN Document Server

    Lenk, Ron

    2016-01-01

    The second edition of Practical Lighting Design with LEDs has been revised and updated to provide the most current information for developing light-emitting diodes products. The authors, noted authorities in the field, offer a review of the most relevant topics including optical performance, materials, thermal design, and modeling and measurement. Comprehensive in scope, the text covers all the information needed to design LEDs into end products.

  3. Light output from six battery operated dental curing lights

    International Nuclear Information System (INIS)

    Shimokawa, Carlos Alberto Kenji; Turbino, Míriam Lacalle; Harlow, Jessie Eudora; Price, Hannah Louise; Price, Richard Bengt

    2016-01-01

    Light Curing Units (LCUs) are used daily in almost every dental office to photocure resins, but because the light is so bright, the user is unable to tell visually if there are any differences between different LCUs. This study evaluated the light output from six dental LCUs: Elipar Deep Cure-S (3M ESPE), Bluephase G2 (Ivoclar Vivadent), Translux 2Wave (Heraeus Kulzer), Optilight Prime (Gnatus), Slim Blast (First Medica) and Led.B (Guilin Woodpecker) with a fully charged battery, after 50, and again after 100, 20 second light exposures. For each situation, the radiant power was measured 10 times with a laboratory-grade power meter. Then, the emission spectrum was measured using a fiber-optic spectrometer followed by an analysis of the light beam profile. It was found there were significant differences in the LCU power and the irradiance values between the LCUs (p < 0.01). The Optilight Prime and Slim Blast LCUs showed a significant reduction in light output after a 50 and 100 exposures, while Bluephase G2 exhibited a significant reduction only after 100 exposures (p < 0.01). The Bluephase G2 and Translux 2 Wave delivered an emission spectrum that had two distinct wavelength emission peaks. Only the Elipar Deep Cure-S and Bluephase G2 LCUs displayed homogeneous light beam profiles, the other LCUs exhibited highly non-homogeneous light beam profiles. It was concluded that contemporary LCUs could have very different light output characteristics. Both manufacturers and researchers should provide more information about the light output from LCUs. - Highlights: • The six LCUs delivered significantly different light output characteristics. • The use of a single irradiance value does not adequately describe the light output from a curing light. • Small differences in the tip area, or how it is defined, will have a large effect on the calculated irradiance. • In some cases there were large portions of the light tip that emitted less than 400 mW/cm². • The radiant

  4. Effect of LED curing on the marginal leakage of a pit and fissure sealant

    OpenAIRE

    Pineda Mejia, Martha Elena; Magister en Estomatología. Profesor Principal. UNMSM. Dpto. Estomatología Rehabilitadora. Facultad Odontología. UNMSM.; Gloria Zevallos, Waldo; Dpto. Estomatología Rehabilitadora. Facultad Odontología. UNMSM.; Abuhadba Hoyos, Tulio; Dpto. Estomatología Rehabilitadora. Facultad Odontología. UNMSM.

    2014-01-01

    The purpose of this study was to evaluate in vitro the curing effect of a light-emitting diode LED unit and conventional halogen light on the marginal leakage of a pit and fissure sealant. We used 40 caries-free permanent premolars recently extracted, which were randomly divided into two groups (n = 20), sealed with a resin based fissure sealant, Helioseal F (Ivoclar Vivadent), according to the manufacturer patterns, then photopolymerized using either L.E.D. light or conventional halogen ligh...

  5. The cytotoxicity of resin composites cured with three light curing units at different curing distances

    OpenAIRE

    Ergün, Gülfem; Egilmez, Ferhan; Cekic Nagas, Isil

    2011-01-01

    Objective: The purpose of this study was to compare the effect of light curing distance on the cytotoxicity of five resin composites cured with three high-power light curing units. Study design: Seven cylindrical discs of each material (Grandio ®, Voco; Filtek ? Z250, 3M ESPE; Clearfil ? AP-X, Kuraray Co. Ltd.; Aelite ? LS, Bisco Inc. and Simile ®, Pentron) were cured. For curing, soft-up mode of quartz-tungsten-halogen, exponential mode of light emitting diode for 20 s, and ramp-curing m...

  6. Automotive LED lamp lighted appearance

    Science.gov (United States)

    Conn, Lawrence G.; Bennett, Larry R.

    2001-05-01

    The automotive optical engineer has an entirely new set of rules to follow for a 'smooth lighted appearance' with the introduction of LEDs into the automotive signal lighting market. To move away from the 'polka-dot' appearance long associated with the usage of LEDs as the light source for automotive lighting, and give the consumer a smooth lighted appearance to his lamp, there are several optical parameters that must be observed. The number and type of LEDs used, the size of the optical elements used, the spacing of the optical elements, plus many other factors all play a critical role and must be considered in the solution to the 'smooth lighted appearance' in an automotive signal lamp. The 'smooth lighted appearance' in an automotive signal lamp has long been a difficult problem to which there is more than one solution. The most visually pleasing and effective solution is not always the most easily obtainable solution since photometry requirements and smooth lighted appearance can be diametric goals. Subsequently the most cost effective and the easily 'doable' solution may not give the ultimate in aesthetically pleasing results for the consumer. Therefore, it is the purpose and intent of this paper to outline the parameters that need to be considered to obtain a 'smooth lighted appearance' for an automotive signal lamp, and to clarify the methods and 'tools' that are required to meet this goal.

  7. The difference nanocomposite hardness level using LED photoactivation based on curing period variations

    Directory of Open Access Journals (Sweden)

    Hasiana Tatian

    2011-03-01

    Full Text Available Polimerizatian is the critical stage to determine the quality of composites resin, this involves isolated monomer carbon double bonds being converted to an extended network of single bonds. Physical and mechanical properties of composites are influenced by the level of conversion attained during polymerization. An adequate light intensity and light curing time are important to obtain the degree of polymerization. The objective of this study is to evaluate the difference of the hardness nanocomposites which activated by LED LCU based on the variation of curing times. This study is a true experimental research. The samples were made from nanocomposites material with cylinder form of 4 mm in depth, 6 mm in diameter. This samples divided into 3 groups of curing times. Group, I was cured for 20's curing time as a control due to manufactory recommended; Group II was cured for 30's, and Group III was cured for 40's and the hardness (Rebound hardness tester was determined using Rebound scale (RS and converted by Mohs scale (MS. There was a very significant level of hardness rate from each group using ANOVA test. The result of the study concludes that there were the differences on the nanocomposites hardness level cured under different curing times 20, 30 and 40 sec. The longer of curing times, the higher level of hardness.

  8. How visible light curing came into dentistry.

    Science.gov (United States)

    Wilson, N H F

    2016-01-01

    The present paper details the history of the introduction of visible light curing into dentistry. This history provides an excellent example of 'out of the box', lateral thinking translation of innovative scientific technology into dentistry. Visible light curing is an important UK contribution to the recent history and current practice of dentistry, with several million visible light curing procedures being carried out globally on a daily basis.

  9. Light curing in orthodontics; should we be concerned?

    Science.gov (United States)

    McCusker, Neil; Lee, Siu Man; Robinson, Stephen; Patel, Naresh; Sandy, Jonathan R; Ireland, Anthony J

    2013-06-01

    Light cured materials are increasingly used in orthodontic clinical practice and concurrent with developments in materials have been developments in light curing unit technology. In recent years the irradiances of these units have increased. The aim of this study was to determine the safe exposure times to both direct and reflected light. The weighted irradiance and safe exposure times of 11 dental curing lights (1 plasma arc, 2 halogen and 8 LED lights) were determined at 6 distances (2-60 cm) from the light guide tip using a spectroradiometer. In addition, using the single most powerful light, the same two parameters were determined for reflected light. This was done at a distance of 10 cm from the reflected light, but during simulated bonding of 8 different orthodontic brackets of three material types, namely stainless steel, ceramic and composite. The results indicate that the LED Fusion lamp had the highest weighted irradiance and the shortest safe exposure time. With this light the maximum safe exposure time without additional eye protection for the patient (at 10 cm), the operator (at 30 cm) and the assistant (at 60 cm) ranged from 2.5 min, 22.1 min and 88.8 min respectively. This indicates a relatively low short term risk during normal operation of dental curing lights. For reflected light at a distance of 10 cm the risk was even lower, but was affected by the material and shape of the orthodontic bracket under test. The short term risks associated with the use of dental curing lights, halogen, LED or plasma, appear to be low, particularly if as is the case adequate safety precautions are employed. The same is true for reflected light from orthodontic brackets during bonding. What is still unclear is the potential long term ocular effects of prolonged exposure to the blue light generated from dental curing lights. Copyright © 2013 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  10. The effect of light curing units, curing time, and veneering materials on resin cement microhardness

    Directory of Open Access Journals (Sweden)

    Nurcan Ozakar Ilday

    2013-06-01

    Conclusion: Light-curing units, curing time, and veneering materials are important factors for achieving adequate dual cure resin composite microhardness. High-intensity light and longer curing times resulted in the highest microhardness values.

  11. An Optimal Cure Process to Minimize Residual Void and Optical Birefringence for a LED Silicone Encapsulant

    Directory of Open Access Journals (Sweden)

    Min-Jae Song

    2014-05-01

    Full Text Available Silicone resin has recently attracted great attention as a high-power Light Emitting Diode (LED encapsulant material due to its good thermal stability and optical properties. In general, the abrupt curing reaction of the silicone resin for the LED encapsulant during the curing process induces reduction in the mechanical and optical properties of the LED product due to the generation of residual void and moisture, birefringence, and residual stress in the final formation. In order to prevent such an abrupt curing reaction, the reduction of residual void and birefringence of the silicone resin was observed through experimentation by introducing the multi-step cure processes, while the residual stress was calculated by conducting finite element analysis that coupled the heat of cure reaction and cure shrinkage. The results of experiment and analysis showed that it was during the three-step curing process that the residual void, birefringence, and residual stress reduced the most in similar tendency. Through such experimentation and finite element analysis, the study was able to confirm that the optimization of the LED encapsulant packaging process was possible.

  12. The cytotoxicity of resin composites cured with three light curing units at different curing distances.

    Science.gov (United States)

    Ergun, Gulfem; Egilmez, Ferhan; Cekic-Nagas, Isil

    2011-03-01

    The purpose of this study was to compare the effect of light curing distance on the cytotoxicity of five resin composites cured with three high-power light curing units. Seven cylindrical discs of each material (Grandio®, Voco; Filtek™ Z250, 3M ESPE; Clearfil™ AP-X, Kuraray Co. Ltd.; Aelite™ LS, Bisco Inc. and Simile®, Pentron) were cured. For curing, soft-up mode of quartz-tungsten-halogen, exponential mode of light emitting diode for 20 s, and ramp-curing mode of plasma arc light curing units for 6 s were used. The curing tip distances were determined as 2 and 9 mm and controlled via the use of metal rings. After ageing the samples for 24 and 72 hours in Dulbecco's Modified Eagle Medium/Ham's F12 (DMEM/F12), cytotoxicity of the extracts to cultured fibroblasts (L 929) was measured by using MTT (tetrazolium salt 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide) assay. The degree of cytotoxicity for each sample was determined according to the reference value represented by the cells in a pure culture medium. Statistical significance was determined using multifactorial analysis of variance. The type of resin composite (p light curing unit (p curing tip distance (p light emitting diode and plasma arc light curing units were used (p=0.184, F=1.448). The results of this study suggest that the light curing units and resin composites should be harmonized to one another and the curing distance between the tip of the light curing unit and the restoration surface should be as close as possible in order to achieve maximal biocompatibility.

  13. Extracting light out of LEDs

    Science.gov (United States)

    Muschaweck, Julius; Wiesmann, Christopher

    2013-08-01

    `External quantum efficiency', that is, the number of photons generated per electron passing through the p-n junction of an LED is probably the most important number to quantify the performance of an LED chip. Although advances in epitaxy have increased the fraction of radiative recombination to extremely high values, the extraction of the precious photons that are trapped in a high refractive index crystal is still tricky. In this brief tutorial, we look at the physics of light extraction both from a geometrical optics/thermodynamic and a wave optics point of view, discussing both random and deterministic surface structures.

  14. Effect of three types of light-curing units on 5-year colour changes of light-cured composite.

    Science.gov (United States)

    Tak, Onjen; Altintas, Subutay Han; Ozturk, Nilgun; Usumez, Aslihan

    2009-03-01

    The purpose of this study was to determine colour changes in a composite cured with tungsten-halogen, light-emitting diode (LED) or a plasma arc after 5 years. Five specimens 10 mm in diameter and 2 mm in height were prepared using Hybrid (Clearfil AP-X) composite for each test group. The corresponding specimens were cured with a tungsten-halogen curing light, a LED unit or with a plasma arc. Specimens were stored in light-proof boxes for 5 years after the curing procedure to avoid further exposure to light and stored in 37 degrees C in 100% humidity. Colorimetric values of the specimens immediately after curing and after 5 years were measured using colorimeter. The DeltaE*( ab ) values varied significantly depending on the curing unit used (p Curing time did not affect the colour changes of the specimens (p = 0.4). The results of this study suggest that composite materials undergo measurable changes due to the curing unit exposure.

  15. LEDs light up the world

    Energy Technology Data Exchange (ETDEWEB)

    Mather, N.

    2004-06-30

    A lighting system using light-emitting diodes, and privately financed by a Canadian engineering professor at the University of Calgary, has been set up in a village in Nepal in 2000. Since then, through the efforts of the 'Light Up The World' Foundation, established by Dr. Irvine-Halliday, projects have lit up thousands of homes in the Philippines, India, Afghanistan, the Galapagos Islands, Mexico, Sri Lanka, and Angola. Although the goal of the project is primarily to provide lighting for reading and writing for school-children, the project has been the source of many other advantages; creation of enterprise, increased employment, enhanced income, gender equality, and improvements in health and safety among them. Since LED lamps in most cases replace kerosene lamps, the system also has significant environmental benefits. The system as originally envisioned creates electricity by pedal-powered generator, or by solar panels connected to a battery, depending on what is available at each home. Each home is connected to the power supply and supplied with low-energy diode lamps. The lights are extremely efficient and many homes can be equipped with them using less energy than it takes to power a single 100-watt light bulb. 5 photos.

  16. Studying Light Color using White LED Lighting

    Science.gov (United States)

    Yamagishi, Misako; Yamaba, Kazuo; Nagata, Manori; Kubo, Chiho; Nokura, Kunihiro

    Recently, white Light Emitting Diodes (LEDs) are receiving attention worldwide as new lighting devices. This study examined effects of a lighting application on performance using white LEDs. The light color—the correlated color temperature (CCT) —was assessed. It affected to psychological states and physiological conditions. Three CCT conditions were respectively set for the experiment: 2500 K, 5000 K, and 8200 K. In all, 20 younger subjects (20-30 years old), 15 middle-aged to elderly subjects (45-60 years old) and 12 elderly subjects (over 65 years-old) participated. They were presented a Numerical Verification (NV) task for performance measurement. The psychological states on performance were evaluated using the lighting assessment questionnaire. The physiological conditions were recorded using an electrocardiograph. Results show that the effects of CCT differ among age groups. Especially, the performance of younger subjects might differ from CCT conditions; elderly subjects are affected by CCT condition because of their visual acuity or response to contrast of objects.

  17. Changes in the temperature of a dental light-cured composite resin by different light-curing units

    Science.gov (United States)

    Rastelli, A. N. S.; Jacomassi, D. P.; Bagnato, V. S.

    2008-08-01

    The purpose of this study was to evaluate the temperature increase during the polymerization process through the use of three different light-curing units with different irradiation times. One argon laser (Innova, Coherent), one halogen (Optilight 501, Demetron), and one blue LED (LEC 1000, MM Optics) LCU with 500 mW/cm2 during 5, 10, 20, 30, 40, 50, and 60 s of irradiation times were used in this study. The composite resin used was a microhybrid Filtek Z-250 (3M/ESPE) at color A2. The samples were made in a metallic mold 2 mm in thickness and 4 mm in diameter and previously light-cured during 40 s. A thermocouple (Model 120 202 EAJ, Fenwal Electronic, Milford, MA, USA) was introduced in the composite resin to measure the temperature increase during the curing process. The highest temperature increase was recorded with a Curing Light 2500 halogen LCU (5 and 31°C after 5 and 60 s, respectively), while the lowest temperature increase was recorded for the Innova LCU based on an argon laser (2 and 11°C after 5 and 60 s, respectively). The temperature recorded for LCU based on a blue LED was 3 and 22°C after 5 and 60 s, respectively. There was a quantifiable amount of heat generated during the visible light curing of a composite resin. The amount of heat generated was influenced by the characteristics of the light-curing units used and the irradiation times.

  18. Effect of light-curing units on the thermal expansion of resin nanocomposites.

    Science.gov (United States)

    Park, Jeong-Kil; Hur, Bock; Ko, Ching-Chang; García-Godoy, Franklin; Kim, Hyung-Il; Kwon, Yong Hoon

    2010-12-01

    To examine the thermal expansion of resin nanocomposites after light-curing using different light-curing units. Four different resin nanocomposites and four different light-curing units [quartz-tungsten-halogen (QTH), light emitting diode (LED), laser, and plasma arc] were chosen. Metal dies were filled with resin to make specimens and light-cured. The light intensity and light-curing time of the QTH and LED light-curing units were 1000 mW/cm2 and 40 seconds, 700 mW/cm2 and 40 seconds for the laser, and 1600 mW/cm2 and 3 seconds for the plasma arc. The coefficient of thermal expansion (CTE) was evaluated using a thermomechanical analyzer (TMA) at temperatures ranging from 30-80 degrees C. The CTE of the resin nanocomposites tested ranged from 28.5 to 65.8 (x 10(-6)/ degrees C), depending on the product and type of light-curing unit used. Among the specimens, Grandio showed the lowest CTE. The specimens cured using the plasma arc unit (Apollo 95E) showed the highest CTE. There was a linear correlation between the CTE and filler content (vol%) (R: -0.94-0.99 depending on the light-curing unit). The results may suggest a careful selection of the light-curing unit because there was more expansion in the specimens cured using the plasma arc unit than those cured by the other units.

  19. Effect of Light Curing Unit Characteristics on Light Intensity Output ...

    African Journals Online (AJOL)

    Background: Modern dental composite restorations are wholly dependent on the use of Visible Light Curing devices. The characteristics of these devices may influence the quality of composite resin restorations. Objective: To determine the characteristics of light curing units (LCUs) in dental clinics in Nairobi and their effect ...

  20. LEDs for general and horticultural lighting

    OpenAIRE

    Girón González, Emilio

    2012-01-01

    The work begins with an introductory part about Light Emitting Diode (or LEDs) and how these devices work. This report also shows an overview of different artificial light sources such as incandescent lamps, fluorescents tube and high-intensity discharge (HID) lamps. The LED lighting is more energy-efficient than other artificial lighting, since they require less energy to operate. The following part of the work reports LEDs for General Lighting that describes some basic concepts such as spec...

  1. Battery Charge Affects the Stability of Light Intensity from Light-emitting Diode Light-curing Units.

    Science.gov (United States)

    Tongtaksin, A; Leevailoj, C

    This study investigated the influence of battery charge levels on the stability of light-emitting diode (LED) curing-light intensity by measuring the intensity from fully charged through fully discharged batteries. The microhardness of resin composites polymerized by the light-curing units at various battery charge levels was measured. The light intensities of seven fully charged battery LED light-curing units-1) LY-A180, 2) Bluephase, 3) Woodpecker, 4) Demi Plus, 5) Saab II, 6) Elipar S10, and 7) MiniLED-were measured with a radiometer (Kerr) after every 10 uses (20 seconds per use) until the battery was discharged. Ten 2-mm-thick cylindrical specimens of A3 shade nanofilled resin composite (PREMISE, Kerr) were prepared per LED light-curing unit group. Each specimen was irradiated by the fully charged light-curing unit for 20 seconds. The LED light-curing units were then used until the battery charge fell to 50%. Specimens were prepared again as described above. This was repeated again when the light-curing units' battery charge fell to 25% and when the light intensity had decreased to 400 mW/cm 2 . The top/bottom surface Knoop hardness ratios of the specimens were determined. The microhardness data were analyzed by one-way analysis of variance with Tukey test at a significance level of 0.05. The Pearson correlation coefficient was used to determine significant correlations between surface hardness and light intensity. We found that the light intensities of the Bluephase, Demi Plus, and Elipar S10 units were stable. The intensity of the MiniLED unit decreased slightly; however, it remained above 400 mW/cm 2 . In contrast, the intensities of the LY-A180, Woodpecker, and Saab II units decreased below 400 mW/cm 2 . There was also a significant decrease in the surface microhardnesses of the resin composite specimens treated with MiniLED, LY-A180, Woodpecker, and Saab II. In conclusion, the light intensity of several LED light-curing units decreased as the battery was

  2. The effects of halogen and light-emitting diode light curing on the depth of cure and surface microhardness of composite resins

    Science.gov (United States)

    Yaman, Batu Can; Efes, Begüm Güray; Dörter, Can; Gömeç, Yavuz; Erdilek, Dina; Büyükgökçesu, Sami

    2011-01-01

    Aim: Light-emitting diode light curing units (LED LCUs) have become more popular than halogen LCUs in routine dental restorative treatment. The aim of the study was to compare the effects of two conventional halogen (Hilux Plus and VIP) and two LED (Elipar FreeLight 2 and Smart Lite) light curing units on the depth of cure and the microhardness of various esthetic restorative materials. Materials and Methods: The curing depth and microhardness of a compomer (Dyract Extra), a resin-modified glass ionomer (Vitremer), a packable composite (Sculpt It), an ormocer (Admira), a hybrid composite (Tetric Ceram), two microhybrid composites (Miris and Clearfil Photo Posterior) and, a nanofil composite (Filtek Supreme) were determined using a scraping method and a hardness tester. A total of 320 samples were prepared using the eight different materials (n = 10 samples for each subgroup). The scraping test was based on ISO 4049:2000. Vicker's microhardness testing was carried out using hardness tester (Zwick 3212). Data were analyzed using one-way analysis of variance (ANOVA), Bonferroni and the Kolmogorov–Smirnov tests. Results: Best microhardness results were obtained with the LED light curing units and Tetric EvoCeram and Filtek Supreme achieved the highest hardness values. The nanofil composite, Filtek Supreme, showed the best curing depth results in all the tested light curing systems. Conclusions: The LEDs were found to be more successful than the halogen units with respect to both curing depth and microhardness properties. PMID:21814353

  3. LED Street Lights in Alaska

    Science.gov (United States)

    2010-09-01

    During winter nights in Alaska, streetlights often remain lit more than half the day, using energy all the while. Around the nation, communities are exploring the use of : light-emitting diode technology for lighting streets and reducing energy use. ...

  4. Plant growth with Led lighting systems

    International Nuclear Information System (INIS)

    Campiotti, C.A.; Bernardini, A.; Di Carlo, F.; Scoccianti, M.; Alonzo, G.; Carlino, M.; Dondi, F.; Bibbiani, C.

    2009-01-01

    Leds lighting is highly relevant for the horticultural industry. Compared to other light sources used for plant production, leds have several properties which are potentially useful in relation to horticulture. However, although LEDs technology has raised strong interest in research for extraterrestrial agriculture, current LEDs panel costs are still too high for commercial adoption in greenhouse sector, and their electrical efficacies do not compete with those of high-pressure sodium lamps, but several manufactures are working to address these issues. When LEDs become practical, their ability to based light sources specifically suitable for photosynthesis and other horticulturally relevant plant properties (i.e. low radiated heat; lighting from within the canopy) will render the narrow band spectrum of LEDs of particular interest for providing light to greenhouse horticulture. A general description of LEDs application and their technical characteristics is briefly reported. [it

  5. Goniometric characterization of LED based greenhouse lighting

    DEFF Research Database (Denmark)

    Thorseth, Anders; Lindén, Johannes; Corell, Dennis Dan

    2015-01-01

    This paper describes a demonstration of goniospectroradiometry for characterizations of new light emitting diode (LED) based luminaries for enhanced photosynthesis in greenhouses. It highlights the differences between measurement of the traditional high pressure sodium (HPS) luminaries and the LED...

  6. An Inexpensive LED Light Sensor

    Science.gov (United States)

    Kutzner, Mickey; Wright, Richard; Kutzner, Emily

    2010-01-01

    Light irradiance measurements are important for students grappling with abstract optical phenomena such as the inverse square law, polarization, diffraction, interference, and spectroscopy. A variety of commercial light sensors are available from scientific vendors such as the CI-6504A from PASCO scientific and the LS-BTA from Vernier Software and…

  7. In vitro evaluation of microleakage under ceramic and metal brackets bonded with LED and plasma arc curing.

    Science.gov (United States)

    Davari, Abdolrahim; Yassaei, Soghra; Karandish, Mariam; Zarghami, Fateme

    2012-09-01

    The aim of the present study was to evaluate these two high intensity light curing units regarding microleakage beneath metal and ceramic brackets. A total of 60 freshly extracted human premolar teeth were randomly divided into four groups of 15 samples; group I: Metal bracket + LED cured, group II: Ceramic bracket + LED cured, group III: Metal bracket + plasma arc cured, group IV: Ceramic bracket + plasma arc cured. After photopolymerization, the teeth were immersed in water and thermocycled (500 cycles between 5 and 55). Specimens were further sealed with nail varnish and stained with 5% basic fuchsin for 24 hours. All of the teeth were sectioned with two parallel longitudinal occlusogingival cuts and examined under a stereomicroscope. The microleakage was measured with a digital caliper and scored from 0 to 3 for marginal microleakage at the bracket-adhesive and adhesive-enamel interfaces from both the occlusal and gingival margins. Microleakage was detected in all groups. The plasma arc cured group showed less microleakage than light emitting diode (LED) cured in all samples at the enamel-adhesive interface at the gingival margin (ceramic brackets, p = 0.009 and metal brackets, p = 0.005). The plasma arc cured samples showed less microleakage than LED cured in metal brackets at the adhesive-brackets interface at the occlusal margin (p = 0.033). While curing with an LED unit, ceramic brackets displayed significantly less microleakage than metal ones at the gingival margin of adhesive-enamel interface (p = 0.013). The gingival margin in all groups exhibited higher microleakage compared with those observed in occlusal sides in all sample groups (p white spot lesions beneath the bracket base.

  8. Pulp chamber temperature increase from curing light units: an in vitro study.

    Science.gov (United States)

    Cantekin, Kenan; Buyuk, Suleyman Kutalmis; Delikan, Ebru; Pedük, Kübra; Demirbuga, Sezer

    2014-01-01

    The purpose of this study was to compare temperature rises in the pulp chamber induced by halogen, plasma arc, and conventional light-emitting diode (LED) curing units with that induced via a new generation LED-curing unit (VALO) in extra power mode. A Class I cavity was prepared on the occlusal surface of 80 extracted caries- free mandibular third molars, which were filled with a microhybrid composite. A thermocouple wire was inserted into the pulp chamber of each tooth to measure temperature changes. The greatest temperature increases were observed during polymerization of composite resin with a halogen curing unit (3.2 degrees Celsius), followed by plasma arc curing (2.07 degrees Celsius) and VALO curing (1.44 degrees Celsius); the lowest temperature rise was with conventional LED curing (1.01 degrees Celsius). There were no statistically significant differences between conventional LED and VALO curing in extra power mode regarding pulp chamber temperature increases when polymerizing composite resin.

  9. Characterization of heat emission of light-curing units.

    Science.gov (United States)

    Wahbi, Mohammed A; Aalam, F A; Fatiny, F I; Radwan, S A; Eshan, I Y; Al-Samadani, K H

    2012-04-01

    This study was designed to analyze the heat emissions produced by light-curing units (LCUs) of different intensities during their operation. The null hypothesis was that the tested LCUs would show no differences in their temperature rises. FIVE COMMERCIALLY AVAILABLE LCUS WERE TESTED: a "Flipo" plasma arc, "Cromalux 100" quartz-tungsten-halogen, "L.E. Demetron 1" second-generation light-emitting diode (LED), and "Blue Phase C5" and "UltraLume 5" third-generation LED LCUs. The intensity of each LCU was measured with two radiometers. The temperature rise due to illumination was registered with a type-K thermocouple, which was connected to a computer-based data acquisition system. Temperature changes were recorded in continues 10 and 20 s intervals up to 300 s. The Flipo (ARC) light source revealed the highest mean heat emission while the L.E. Demetron 1 LED showing the lowest mean value at 10 and 20 s exposure times. Moreover, Cromalux (QTH) recorded the second highest value for all intervals (12.71, 14.63, 14.60) of heat emission than Blue Phase C5 (LED) (12.25, 13.87, 13.69), interestingly at 20 s illumination for all intervals the highest results (18.15, 19.27, 20.31) were also recorded with Flipo (PAC) LCU, and the lowest (6.71, 5.97, 5.55) with L.E. Demetron 1 LED, while Blue Phase C5 (LED) recorded the second highest value at the 1st and 2nd 20 s intervals (14.12, 11.84, 10.18) of heat emission than Cromalux (QTH) (12.26, 11.43, 10.26). The speed of temperature or heat rise during the 10 and 20 s depends on light intensity of emitted light. However, the QTH LCU was investigated resulted in a higher temperature rise than LED curing units of the same power density. The PAC curing unit induced a significantly higher heat emission and temperature increase in all periods, and data were statistically different than the other tested groups (p < .05). LED (Blue Phase C5) was not statistically significant (p < .05) (at 10 s) than QTH units, also LED (Blue

  10. Effects of Different Light Curing Units/Modes on the Microleakage of Flowable Composite Resins

    Science.gov (United States)

    Yazici, A. Ruya; Celik, Cigdem; Dayangac, Berrin; Ozgunaltay, Gul

    2008-01-01

    Objectives The aim of this in vitro study was to evaluate the influence of different light curing units and modes on microleakage of flowable composite resins. Methods Eighty Class V cavities were prepared in buccal and lingual surfaces of 40 extracted human premolars with cervical wall located in dentin and the occlusal wall in enamel. These teeth were randomly assigned into two groups (n=20) and restored with different flowable composites; Group I: Esthet-X Flow, Group II: Grandio Flow. Each group was randomly divided into four subgroups; while the samples of the first subgroup were polymerized with conventional Halogen light, the rest of them were polymerized with different curing modes of Light Emitting Diode (LED). The second subgroup was polymerized with fast-curing; the third subgroup with pulse-curing and those of the fourth subgroup with step-curing modes of LED. After the samples were thermocycled and immersed in dye, they were longitudinally sectioned. Dye penetration was assessed under a stereomicroscope. Data were analyzed by Kruskal-Wallis and Mann-Whitney U tests. Results None of the restorations showed leakage on enamel margins. On dentin margins no significant differences were observed between flowable composite resins polymerized with halogen light (P>.05). While step curing mode of LED presented significant differences between the resins, the difference was insignificant when fast-curing and pulse-curing mode of LED were used. No statistically significant differences were observed between curing units for Esthet-X Flow samples. For Grandio Flow samples, only step-curing mode of LED caused statistically higher leakage scores than halogen and other curing modes of LED (P<.05). Conclusions The effect of curing units’ type and curing mode on flowable composite resin leakage might be material-dependent. PMID:19212529

  11. Localised irradiance distribution found in dental light curing units.

    Science.gov (United States)

    Michaud, Pierre-Luc; Price, Richard B T; Labrie, Daniel; Rueggeberg, Frederick A; Sullivan, Braden

    2014-02-01

    To measure the localised irradiance and wavelength distributions from dental light curing units (LCUs) and establish a method to characterise their output. Using a laboratory grade integrating sphere spectrometer system (Labsphere and Ocean Optics) the power, irradiance, and spectral emission were measured at the light tips of four LCUs: one plasma-arc (PAC) unit, one single peak blue light-emitting diode (blue-LED) unit, and two polywave LED (poly-LED) units. A beam profiler camera (Ophir Spiricon) was used to record the localised irradiance across the face of the light tips. The irradiance-calibrated beam profile images were then divided into 45 squares, each 1mm(2). Each square contained the irradiance information received from approximately 3200 pixels. The mean irradiance value within each square was calculated, and the distribution of irradiance values among these 45 squares across the tip-ends was examined. Additionally, the spectral emission was recorded at various regions across each light tip using the integrating sphere with a 4-mm diameter entrance aperture. The localised irradiance distribution was inhomogeneous in all four lights. The irradiance distribution was most uniformly distributed across the PAC tip. Both the irradiance and spectral emission from the poly-LED units were very unevenly distributed. Reporting a single irradiance value or a single spectral range to describe the output from a curing light is both imprecise and inappropriate. Instead, an image of both the irradiance distribution and the distribution of the spectral emission across the light tip should be provided. The localised beam irradiance profile at the tip of dental LCUs is not uniform. Poly-LED units may deliver spectrally inhomogeneous irradiance profiles. Depending on the photoinitiator used in the RBC and the orientation of the LCU over the tooth, this non-uniformity may cause inadequate and inhomogeneous resin polymerisation, leading to poor physical properties, and

  12. Practical lighting design with LEDs

    CERN Document Server

    Lenk, Ron

    2011-01-01

    "This book covers all of the information needed to design LEDs into end-products. It is a practical guide, primarily explaning how things are done by practicing engineers. Equations are used only for practical calculations, and are kept to the level of high-school algebra. There are numerous drawings and schematics showing how things such as measurements are actually made, and showing curcuits that actually work. There are practical notes and examples embedded in the text that give pointers and how-to guides on many of the book's topics. After reading each chapter of the book, readers will have the knowledge to implement practical designs. This book will be kept as a reference tool for years to come"--

  13. Effect of power density of curing unit, exposure duration, and light guide distance on composite depth of cure.

    Science.gov (United States)

    Lindberg, Anders; Peutzfeldt, Anne; van Dijken, Jan W V

    2005-06-01

    This in vitro study compared the depth of cure obtained with six quartz tungsten halogen and light-emitting diode curing units at different exposure times and light tip-resin composite distances. Resin composite specimens (Tetric Ceram, A3; diameter 4 mm, height 6 mm) were exposed from 0-, 3-, and 6-mm distance. The curing units (200-700 mW/cm2) were used for standard (20 and 40 s), pulse-delay mode (initial exposure of 3 s at 200 mW/cm2, followed by a resting period of 3 min and a final exposure of 10 or 30 s at 600 mW/cm2), or soft-start curing (40 s; exponential ramping). Curing depth was determined by measurement of Wallace hardness for each half millimeter starting at 0.5 mm from the top surface. For each specimen, a mean H(W) value was calculated from the H(W) values determined at the depths of 2.0 mm and less (0.5, 1.0, 1.5, and 2.0 mm, respectively). The depth of cure for each specimen was found by determining the greatest depth before an H(W) value exceeding the minimal H(W) value by 25% occurred. For all curing units, an increase in exposure time led to significantly higher depth of cure. Increasing the light tip-resin composite distance significantly reduced the depth of cure. With a light tip-resin composite distance of 6 mm, median values of depth of cure varied between 2.0 and 3.5 mm following a 20-s (or 3+10 s) exposure and between 3.0 and 4.5 mm following a 40-s (or 3+30 s) exposure. The composite situated above the depth of cure value cured equally well with all curing units. At both exposure times, Luxomax resulted in the significantly lowest depth of cure, and Astralis 7 yielded significantly higher depth. At both exposure times, a significant linear correlation was found between the determined power densities of the curing units and the pooled depth of cure values obtained. It seems that for the resin composite tested, the recommended exposure time of 40 s per 2-mm increment may be reduced to 20 s, or that increments may be increased from 2 to 3

  14. Goniometric characterization of LED based greenhouse lighting

    DEFF Research Database (Denmark)

    Thorseth, Anders; Lindén, Johannes; Corell, Dennis Dan

    2015-01-01

    This paper describes a demonstration of goniospectroradiometry for characterizations of new light emitting diode (LED) based luminaries for enhanced photosynthesis in greenhouses. It highlights the differences between measurement of the traditional high pressure sodium (HPS) luminaries and the LED...... based luminaries. The LED based luminaries are compared to traditional HPS luminaries; in terms of energy efficiency with regard to the photosynthetic photon flux, and the LED luminaries were found to be more effective than the HPS luminaries...

  15. LED Shipboard Lighting: A Comparative Analysis

    Science.gov (United States)

    2009-12-01

    viability of retrofitting the Navy fleet with newer lighting technology . C. RESEARCH QUESTION The research project provided to NPS by Dr. Larry Schuette...LED is a key component in today’s lighting technology . Modern households use LEDs in such components as digital video disc, (DVD) readers...manufactures that the Navy is serious in implementing lighting technology with a multi- year demonstration seeing the benefits provided by the manufactures

  16. Effect of light-curing units on the thermal expansion of resin nanocomposites

    Science.gov (United States)

    Park, Jeong-Kil; Hur, Bock; Ko, Ching-Chang; García-Godoy, Franklin; Kim, Hyung-Il; Kwon, Yong Hoon

    2011-01-01

    Purpose To examine the thermal expansion of resin nanocomposites after light-curing using different light-curing units. Methods Four different resin nanocomposites and four different light-curing units [quartz-tungsten-halogen (QTH), light emitting diode (LED), laser, and plasma arc] were chosen. Metal dies were filled with resin to make specimens and light-cured. The light intensity and light-curing time of the QTH and LED light-curing units were 1000 mW/cm2 and 40 seconds, 700 mW/cm2 and 40 seconds for the laser, and 1600 mW/cm2 and 3 seconds for the plasma arc. The coefficient of thermal expansion (CTE) was evaluated using a thermomechanical analyzer (TMA) at temperatures ranging from 30–80°C. Results The CTE of the resin nanocomposites tested ranged from 28.5 to 65.8 (×10−6/°C), depending on the product and type of light-curing unit used. Among the specimens Grandio showed the lowest CTE. The specimens cured using the plasma arc unit (Apollo 95E) showed the highest CTE. There was a linear correlation between the CTE and filler content (vol%) (R: −0.94~−0.99 depending on the light-curing unit). The results may suggest a careful selection of the light-curing unit because there was more expansion in the specimens cured using the plasma arc unit than those cured by the other units. (Am J Dent 2010;23:331–334). PMID:21344832

  17. LED Lighting in a Performing Arts Building

    Energy Technology Data Exchange (ETDEWEB)

    Miller, N. J.; Kaye, S. M. [Univ. of Florida, Gainesville, FL (United States); Coleman, P. M. [Univ. of Florida, Gainesville, FL (United States); Wilkerson, A. M.; Perrin, T. E.; Sullivan, G. P. [Efficiency Solutions, Inc., Richland, WA (United States)

    2014-07-31

    At the University of Florida in Gainesville, the DOE Solid-State Lighting GATEWAY program evaluated LED architectural and theatrical lighting in four academic/performance-related spaces within the Nadine McGuire Theatre + Dance Pavilion. Due to a wise choice of products and luminaire light distributions, the change brought significant quality improvements including improved controllability and color.

  18. Influence of the Light Source and Curing Parameters on Microhardness of a Silorane-Based Dental Composite Material

    OpenAIRE

    Malara P.; Czech Z.; Świderski W.

    2016-01-01

    The aim of the study was to determine the influence of the light source and the light-curing parameters (the distance of the material from the light source and time of light-curing) on microhardness of Flitek Silorane dental composite material. Standardized samples of Filtek Silorane material were cured using two types of Light Curing Units (LCUs) – halogen and LED. The distance of the light source and time of curing differed between samples. The Knoop’s microhardness was tested using microha...

  19. Light-Curing Adhesive Repair Tapes

    Science.gov (United States)

    Allred, Ronald; Haight, Andrea Hoyt

    2009-01-01

    Adhesive tapes, the adhesive resins of which can be cured (and thereby rigidized) by exposure to ultraviolet and/or visible light, are being developed as repair patch materials. The tapes, including their resin components, consist entirely of solid, low-outgassing, nonhazardous or minimally hazardous materials. They can be used in air or in vacuum and can be cured rapidly, even at temperatures as low as -20 C. Although these tapes were originally intended for use in repairing structures in outer space, they can also be used on Earth for quickly repairing a wide variety of structures. They can be expected to be especially useful in situations in which it is necessary to rigidize tapes after wrapping them around or pressing them onto the parts to be repaired.

  20. Curing efficiency of three light emitting diode units at different curing profiles

    Directory of Open Access Journals (Sweden)

    Priyanka Verma

    2016-01-01

    Conclusions: Reduction of exposure time to 6 s with high-intensity curing light seemed to be clinically acceptable and should be recommended. Curing of metal brackets with single exposure from buccal side showed lower shear bond strength values.

  1. Pengaruh Penggunaan Light-Emitting Diode Light Curing Unit Dan Halogen Light Curing Unit Terhadap Microleakage Dengan Jarak Penyinaran 0 MM Dan 5 MM Pada Restorasi Klas V (Penelitian In Vitro)

    OpenAIRE

    Yumira

    2010-01-01

    Kelemahan utama dari resin komposit adalah terjadinya kontraksi polimerisasi selama pengerasan sehingga timbul kebocoran mikro. Kebocoran mikro sering menimbulkan masalah pada kavitas klas V resin komposit seperti hipersensitivitas, karies rekuren, penyakit pulpa, dan diskolorissasi marginal. Penelitian ini bertujuan untuk mengamati dan mengetahui perbedaan kebocoran mikro pada restorasi resin komposit yang dipolimerisasi dengan LED light curing unit dan halogen light curing unit dengan jarak...

  2. Temperature rise produced by different light-curing units through dentin.

    Science.gov (United States)

    Yazici, A Rüya; Müftü, Ali; Kugel, Gerard

    2007-11-01

    This study investigated the temperature rise caused by different light curing units and the temperature increase in dentin of different thicknesses. Dentin discs of 1.0 and 2.0 mm thicknesses were prepared from extracted human mandibular molars. Temperatures were recorded directly at the surface of the light guide tip, under dentin discs with different thicknesses, and through a sandwich composed of 2 mm thick cured composite and dentin using a K-type thermocouple. The curing units used were two quartz-tungsten-halogen lights (Spectrum and Elipar Trilight-ET) and a light-emitting diode (LED). The highest temperature rise was observed under a Mylar strip using ET standard mode. Under 1 and 2 mm thick dentin barriers, the lowest temperature rise was measured for the LED curing light. Significant differences in temperature rise existed among all curing units except between the Spectrum and ET exponential modes under a 1 mm thick dentin barrier with cured composite. Temperature rises were insignificant between the Spectrum and ET exponential modes and between two modes of Trilight when the same experimental setup was used under a 2 mm thick dentin barrier. For all curing units, temperature elevation through 2 mm of dentin was less than for 1 mm of dentin thickness. The ET standard mode produced the highest and the LED produced the lowest temperature rise for all tested conditions. The thickness of dentin and light-curing unit might affect temperature transmission.

  3. Biaxial flexural strength of high-viscosity glass-ionomer cements heat-cured with an LED lamp during setting

    NARCIS (Netherlands)

    Molina, G. Fabian; Cabral, R.J.; Mazzola, I.; Lascano, L. Brain; Frencken, J.E.F.M.

    2013-01-01

    Adding heat to glass ionomers during setting might improve mechanical properties. The aim was to compare the biaxial flexural strength (BFS) between and within four glass ionomers, by time of exposure to a high-intensity LED light-curing unit. Materials and methods. Samples of Fuji 9 Gold Label,

  4. Temperature rise induced by some light emitting diode and quartz-tungsten-halogen curing units.

    Science.gov (United States)

    Asmussen, Erik; Peutzfeldt, Anne

    2005-02-01

    Because of the risk of thermal damage to the pulp, the temperature rise induced by light-curing units should not be too high. LED (light emitting diode) curing units have the main part of their irradiation in the blue range and have been reported to generate less heat than QTH (quartz-tungsten-halogen) curing units. This study had two aims: first, to measure the temperature rise induced by ten LED and three QTH curing units; and, second, to relate the measured temperature rise to the power density of the curing units. The light-induced temperature rise was measured by means of a thermocouple embedded in a small cylinder of resin composite. The power density was measured by using a dental radiometer. For LED units, the temperature rise increased with increasing power density, in a statistically significant manner. Two of the three QTH curing units investigated resulted in a higher temperature rise than LED curing units of the same power density. Previous findings, that LED curing units induce less temperature rise than QTH units, does not hold true in general.

  5. Hardness of composite resin polymerized with different light-curing units

    Directory of Open Access Journals (Sweden)

    Hengameh Safarcherati

    2012-09-01

    Full Text Available Introduction: The degree of polymerization depends on the type of light-curing unit. The aim of this study was to compare the hardness of composite resin cured by LED and Halogen light curing units. Methods: In this experimental study, 20 cylindrical samples of Tetric Ceram composite were prepared. Half of them were cured with Ultralume 2 LED and the other half with Astralis 7 Halogen light curing unit. In the depths of 0,1,2 and 3 mm from surface, one point in peripheral and one point in central portion were marked ,then the hardness of these points was measured by Vickers test . The data was analyzed by a pvalue less than 0.05 considered as significant. Results: The mean hardness of samples cured by LED was more than halogen group in different depths and this difference was statistically significant in peripheral points (p=.048 but this was not significant in central points (p=0.644. The mean hardness in both groups had a decreasing trend from surface to the deep parts in central and peripheral parts and this was more in the central parts. Conclusions: Composites cured by LED light curing unit showed more hardness in similar depths, besides the hardness of composites in central parts is more than the peripheral ones in both groups.

  6. Halogen light versus LED for bracket bonding: shear bond strength

    Directory of Open Access Journals (Sweden)

    Paulo Eduardo Guedes Carvalho

    2013-02-01

    Full Text Available INTRODUCTION: LED light-curing devices seek to provide a cold light activator which allows protocols of material polymerization with shorter duration. OBJECTIVE: The present study aimed to evaluate the shear bond strength of bracket bonding using three types of light-curing devices: One with halogen light (Optilight Plus - Gnatus and two with LEDs (Optilight CL - Gnatus and Elipar Freelight - 3M/ESPE. RESULTS: Comparing the results by analysis of variance, the Gnatus LED device showed an inferior statistical behavior in relation to other light sources, when activated by a short time. But, when it was used for 40 seconds, the polymerization results were consistent with the other evaluated sources. The device with the best average performance was the halogen light, followed by the 3M/ESPE LED. CONCLUSION: It was concluded that the LEDs may be indicated in orthodontic practice, as long as a protocol is used for the application of light with the activation time of 40 seconds.INTRODUÇÃO: os aparelhos de fotopolimerização por LED buscam proporcionar uma luz ativadora fria, que possibilite protocolos de polimerização do material com menor tempo de duração. OBJETIVO: avaliar a resistência à tração da colagem de braquetes, utilizando três tipos de aparelhos fotoativadores: um de luz halógena (Optilight Plus - Gnatus e outros dois de LED (Optilight CL - Gnatus; e Elipar Freelight - 3M/Espe. RESULTADOS: comparando os resultados por meio da análise de variância, o aparelho de LED Gnatus apresentou comportamento estatístico inferior em relação às outras fontes de luz, quando ativado por tempo reduzido. Já quando foi utilizado o tempo de 40 segundos, os resultados de polimerização foram compatíveis com as demais fontes avaliadas. O aparelho que apresentou melhor desempenho médio foi o de luz halógena, seguido pelo LED 3M/Espe. CONCLUSÃO: concluiu-se que os LEDs podem ser indicados na prática ortodôntica, uma vez que seja utilizado

  7. Bulk-Fill Composites: Effectiveness of Cure With Poly- and Monowave Curing Lights and Modes.

    Science.gov (United States)

    Gan, J K; Yap, A U; Cheong, J W; Arista, N; Tan, Cbk

    This study compared the effectiveness of cure of bulk-fill composites using polywave light-emitting diode (LED; with various curing modes), monowave LED, and conventional halogen curing lights. The bulk-fill composites evaluated were Tetric N-Ceram bulk-fill (TNC), which contained a novel germanium photoinitiator (Ivocerin), and Smart Dentin Replacement (SDR). The composites were placed into black polyvinyl molds with cylindrical recesses of 4-mm height and 3-mm diameter and photopolymerized as follows: Bluephase N Polywave High (NH), 1200 mW/cm 2 (10 seconds); Bluephase N Polywave Low (NL), 650 mW/cm 2 (18.5 seconds); Bluephase N Polywave soft-start (NS), 0-650 mW/cm 2 (5 seconds) → 1200 mW/cm 2 (10 seconds); Bluephase N Monowave (NM), 800 mW/cm 2 (15 seconds); QHL75 (QH), 550 mW/cm 2 (21.8 seconds). Total energy output was fixed at 12,000 mJ/cm 2 for all lights/modes, with the exception of NS. The cured specimens were stored in a light-proof container at 37°C for 24 hours, and hardness (Knoop Hardness Number) of the top and bottom surfaces of the specimens was determined using a Knoop microhardness tester (n=6). Hardness data and bottom-to-top hardness ratios were subjected to statistical analysis using one-way analysis of variance/Scheffe's post hoc test at a significance level of 0.05. Hardness ratios ranged from 38.43% ± 5.19% to 49.25% ± 6.38% for TNC and 50.67% ± 1.54% to 67.62% ± 6.96% for SDR. For both bulk-fill composites, the highest hardness ratios were obtained with NM and lowest hardness ratios with NL. While no significant difference in hardness ratios was observed between curing lights/modes for TNC, the hardness ratio obtained with NM was significantly higher than the hardness ratio obtained for NL for SDR.

  8. Photobiocatalytic alcohol oxidation using LED light sources

    NARCIS (Netherlands)

    Rauch, M.C.R.; Schmidt, S.; Arends, I.W.C.E.; oppelt, K.; Kara, S; Hollmann, F.

    2016-01-01

    The photocatalytic oxidation of NADH using a flavin photocatalyst and a simple blue LED light source is reported. This in situ NAD+ regeneration system can be used to promote biocatalytic, enantioselective oxidation reactions. Compared to the traditional use of white light bulbs this method enables

  9. Effect of light curing methods on microleakage and microhardness of different resin sealants.

    Science.gov (United States)

    Duangthip, Duangporn; Ballungpattama, Suda; Sitthisettapong, Thanya

    2011-07-01

    This study's purpose was to evaluate the effect of light curing methods on the microleakage and microhardness of sealants. The Elipar Free Light 2 light emitting diode (LED) with 10- and 20-second curing times, and the Elipar 2500 halogen light with a 20-second curing time were compared. Four different sealants were used: (1) Delton Clear; (2) Delton Opaque; (3) UltraSeal XT Clear; and (4) UltraSeal XT Opaque. Specimens were fabricated in a silicone mold (2-mm thick) and cured. Knoop hardness was measured at the bottom and top surfaces. For the microleakage evaluation, 120 human molars were divided into 12 groups and sealed with the sealants and curing methods, as stated previously. The teeth were thermocycled and immersed in 2% methylene blue for 24 hours. Each tooth was sectioned and examined for dye penetration. There were no statistically significant differences in the microleakage of sealants polymerized by either the halogen or LED curing methods. The microhardness of sealants varied according to the type of material and curing method. A 10-second polymerization time with light emitting diodes was not sufficient to cure the 2-mm-thick opaque or high filler loaded sealants. Decreasing the curing time, however, had no effect on the microleakage of the sealants.

  10. Distributed dimming control for LED lighting.

    Science.gov (United States)

    Lee, Sang Hyun; Kwon, Jae Kyun

    2013-11-04

    This paper presents a distributed energy-saving lighting strategy for the arrangements of a lighting network consisting of a group of light-emitting diode (LED) lamps and users. LED lamps have a dimming support feature to meet the illuminance requirements imposed by individual users. Both groups interact with each other via visible light communication (VLC) or other wireless communication features. This work aims to identify a configuration of lamps leading to the maximal energy saving in adaptive and distributed ways. To this end, a distributed assignment strategy is developed based on a message-passing framework where only local interactions among lamps and users are allowed for calculations and exchanges of the information on their status. The simulation results show that the proposed algorithm outperforms other distributed algorithms in a range of indoor lighting configurations.

  11. Effect of light energy density on conversion degree and hardness of dual-cured resin cement.

    Science.gov (United States)

    Komori, Paula Carolina de Paiva; de Paula, Andréia Bolzan; Martin, Airton Abrāo; Tango, Rubens Nisie; Sinhoreti, Mario Alexandre Coelho; Correr-Sobrinho, Lourenço

    2010-01-01

    This study evaluated the effect of different light energy densities on conversion degree (CD) and Knoop hardness number (KHN) of RelyX ARC (RLX) resin cement. After manipulation according to the manufacturer's instructions, RLX was inserted into a rubber mold (0.8 mm x 5 mm) and covered with a Mylar strip. The tip of the light-curing unit (LCU) was positioned in contact with the Mylar surface. Quartz-tungsten-halogen (QTH) and light-emitting diode (LED) LCUs with light densities of 10, 20 and 30 J/cm2 were used to light-cure the specimens. After light curing, the specimens were stored dry in lightproof containers at 37 degrees C. After 24 hours, the CD was analyzed by FT-Raman and, after an additional 24-hours, samples were submitted to Knoop hardness testing. The data of the CD (%) and KHN were submitted to two-way ANOVA and the Tukey's test (alpha = 0.05). QTH and LED were effective light curing units. For QTH, there were no differences among the light energy densities for CD or KHN. For LED, there was a significant reduction in CD with the light energy density set at 10 J/cm2. KHN was not influenced by the light-curing unit and by its light energy density.

  12. Wheat Under LED's (Light Emitting Diodes)

    Science.gov (United States)

    2004-01-01

    Astroculture is a suite of technologies used to produce and maintain a closed controlled environment for plant growth. The two most recent missions supported growth of potato, dwarf wheat, and mustard plants, and provided scientists with the first opportunity to conduct true plant research in space. Light emitting diodes have particular usefulness for plant growth lighting because they emit a much smaller amount of radiant heat than do conventional lighting sources and because they have potential of directing a higher percentage of the emitted light onto plants surfaces. Furthermore, the high output LED's have emissions in the 600-700 nm waveband, which is of highest efficiency for photosynthesis by plants.

  13. LED light recycling using double prisms

    Science.gov (United States)

    Ouyang, George; Li, Kenneth

    2013-09-01

    A novel LED recycling scheme using double prisms is presented. Two identical triangular prisms with square bases, one cross-stacked on top of the other, are tight-fit into a mirrored light tunnel. The whole prism/light tunnel assembly is then mounted on top of a square LED source, whose emitting area is the same as that of the base plane of the said prism/light tunnel assembly. Each prism acts as a tapered-down light guide in one dimension, which selectively retro-reflects high angle light along that direction. The outer light tunnel serves as a mirrored wall that folds back any light that escapes outside the two prisms. For a given collection cone angle, the height of the two prisms is optimized using ASAP, a commercial ray-tracing software. Simulation and experimental results show promise in significantly increasing the brightness of the LED sources within the collection cone. Specifically for a 4x recycling ratio a 70% recycling gain in center illuminance has been achieved (i.e., illuminance measured in the forward direction). This scheme has advantages over previous recycling configurations due to its compactness and ease of mounting. For example, compared to Wavien's spherical reflector approach that has been previously published, the current recycling configuration is much smaller in size because instead of fitting a much larger mirrored reflector on top of the LED source, this time we're using a structure that has the same lateral dimensions as those of the LED source itself. Further improvement is also possible if optimization of various system parameters is carried out.

  14. Effect of light intensity on the cure characteristics of photo ...

    African Journals Online (AJOL)

    Objective: To determine the light intensity emitted by light curing units (LCUs) and its effect on the cure characteristics of composites polymerised with it. Design: A laboratory based cross sectional study. Setting: Public and private dental clinics in Nairobi, Kenya. Results: Thirty five (42.17%) LCUs produced light of intensity ...

  15. Experiencing LED: Lighting: New Form and Experiential Qualities Emerging in Lighting Systems using LED

    DEFF Research Database (Denmark)

    Petersen, Kjell Yngve; Kristensen, Ole; Søndergaard, Karin

    2012-01-01

    The project investigates what new forms and qualities of light emerge from technologies such as LED, with a particular focus on basic form qualities and parameters. Existing linear functional understandings of the relation between light source, light flow, reflection and visibility is challenged ...... by relational understandings, where the materiality and visibility of the light emerge through mutual influences between several adaptive and transformative elements....

  16. effect of light intensity on the cure characteristics of photo

    African Journals Online (AJOL)

    2012-05-05

    May 5, 2012 ... of material factors on the variables being measured. Light curing units in the sampled clinics were used to cure the composite specimens, which were all cylindrical. The one for micro-hardness evaluation measured eight millimetres in diameter and three millimetres in height while the other for depth of cure.

  17. Sustainable LED Fluorescent Light Replacement Technology

    Energy Technology Data Exchange (ETDEWEB)

    None, None

    2011-09-30

    Ilumisys and the National Center for Manufacturing Sciences (NCMS) partnered on a three-year project awarded by the United States (U.S.) Department of Energy (DOE), to quantify the impacts of LED lamps, incandescent lamps and fluorescent benchmark lamps over a product lifecycle – i.e. to develop a sustainable design and manufacturing strategy that addresses product manufacturing, use, recycling and disposal scenarios for LED-based lighting. Based on the knowledge gained from extensive product tear-down studies of fluorescent and screw-in lighting products, lifecycle assessment tools, and accelerated lifecycle testing protocols, an interactive Sustainable LED Design Guide has been developed to aid architectural and lighting designers and engineers in making design decisions that consider three important environmental impacts (greenhouse gas emissions, energy use and mercury emission) across all phases of the life of an LED lighting product. Critical information developed for the lifecycle analysis and product feature comparisons is the useful life of the lighting product as well as its performance. The Design Guide is available at www.ncms.org, and was developed based on operational and durability testing of a variety of lighting products including power consumption, light output, and useful life of a lamp in order to allow a more realistic comparison of lamp designs. This report describes the main project tasks, results and innovative features of the lifecycle assessment (LCA)-based design tools, and the key considerations driving the sustainable design of LED lighting systems. The Design Guide incorporates the following three novel features for efficiently evaluating LED lighting features in value-chains: Bill-of-Materials (BOM) Builder – Designers may import process data for each component and supply functional data for the product, including power, consumption, lumen output and expected useful life: Environmental Impact Review – Designs are comparable

  18. Characterizing the output settings of dental curing lights.

    Science.gov (United States)

    Harlow, J E; Sullivan, B; Shortall, A C; Labrie, D; Price, R B

    2016-01-01

    For improved inter-study reproducibility and ultimately improved patient care, researchers and dentists need to know what electromagnetic radiation (light) is emitted from the light-curing unit (LCU) they are using and what is received by the resin. This information cannot be obtained from a dental radiometer, even though many studies have used a dental radiometer. The light outputs from six LCUs (two QTH and four broad-spectrum LED units) were collected in real-time using an integrating sphere connected to a fiberoptic spectrometer during different light exposures. It was found that the spectral emissions were unique to each LCU, and there was no standardization in what was emitted on the various ramp (soft-start) settings. Relative to the normal use setting, using the ramp setting reduced the radiant energy (J) delivered from each LCU. For one of the four broad-spectrum LED LCUs, the spectral emissions in the violet range did not increase when the overall radiant power output was increased. In addition, this broad-spectrum LED LCU emitted no light from the violet LED chip for the first 5s and only emitted violet light when the ramp phase finished. A single irradiance value derived from a dental radiometer or from a laboratory grade power meter cannot adequately describe the output from the LCU. Manufacturers should provide more information about the light output from their LCUs. Ideally, future assessments and research publications that include resin photopolymerization should report the spectral radiant power delivered from the LCU throughout the entire exposure cycle. Copyright © 2015 Elsevier Ltd. All rights reserved.

  19. effect of light curing unit characteristics on light intensity output

    African Journals Online (AJOL)

    2013-09-09

    Sep 9, 2013 ... LEDs produced light of low intensity (2) which resulted in composites of inferior properties than. QTH lamps (9, 11). Newer generations of LEDs try to address these deficits through higher intensities and being of dual spectrum. This allows them to be used with non-CQ composites (7). However, the high.

  20. Comparison of temperature rise in the pulp chamber with different light curing units: An in-vitro study.

    Science.gov (United States)

    Rajesh Ebenezar, A V; Anilkumar, R; Indira, R; Ramachandran, S; Srinivasan, M R

    2010-07-01

    This in vitro study was designed to measure and compare the temperature rise in the pulp chamber with different light curing units. The study was done in two settings-in-vitro and in-vivo simulation. In in-vitro setting, 3mm and 6mm acrylic spacers with 4mm tip diameter thermocouple was used and six groups were formed according to the light curing source- 3 Quartz-Tungsten-Halogen (QTH) units and 3 Light-Emitting-Diode (LED) units. For the LED units, three modes of curing like pulse-cure mode, fast mode and ramp mode were used. For in-vivo simulation, 12 caries free human third molar tooth with fused root were used. K-type thermocouple with 1 mm tip diameter was used. Occlusal cavity was prepared, etched, rinsed with water and blot dried; bonding agent was applied and incremental curing of composite was done. Thermal emission for each light curing agent was noted. Temperature rise was very minimal in LED light cure units than in QTH light cure units in both the settings. Temperature rise was minimal at 6mm distance when compared to 3 mm distance. Among the various modes, fast mode produces the less temperature rise. Temperature rise in all the light curing units was well within the normal range of pulpal physiology. Temperature rise caused due to light curing units does not result in irreversible pulpal damage.

  1. Comparação da influência entre tempos de polimerização em resinas compostas polimerizadas com LED e Luz Incandescente Comparison of the influence of curing times applied to composite resins cured with LED and Incandescent Light

    OpenAIRE

    Michele P. M. Ulhoa; Lúcio R. S. Santana; Eduardo C. Bianchi; Carlos E. D. Cruz; Paulo R. Aguiar; César A. de Freitas; Márcia F. A. de Freitas

    2007-01-01

    O propósito deste trabalho é fazer uma comparação entre resinas poliméricas dentárias, polimerizadas por aparelhos baseados em lâmpada halógena e diodo emissor de Luz (LED), utilizando-se o método do disco retificado aperfeiçoado para odontologia e os respectivos valores de microdureza. Foram realizados testes em amostras de resinas compostas de 5 diferentes marcas, polimerizadas a tempos de 10, 20 e 40 s, pelos dois aparelhos. A análise estatística dos valores de microdureza e agressividade ...

  2. UV LED lighting for automated crystal centring

    International Nuclear Information System (INIS)

    Chavas, Leonard M. G.; Yamada, Yusuke; Hiraki, Masahiko; Igarashi, Noriyuki; Matsugaki, Naohiro; Wakatsuki, Soichi

    2011-01-01

    A low-cost light-emitting diode (LED) UV source has been developed for facilitating macromolecular sample centring in the X-ray beam. A direct outcome of the exponential growth of macromolecular crystallography is the continuously increasing demand for synchrotron beam time, both from academic and industrial users. As more and more projects entail screening a profusion of sample crystals, fully automated procedures at every level of the experiments are being implemented at all synchrotron facilities. One of the major obstacles to achieving such automation lies in the sample recognition and centring in the X-ray beam. The capacity of UV light to specifically react with aromatic residues present in proteins or with DNA base pairs is at the basis of UV-assisted crystal centring. Although very efficient, a well known side effect of illuminating biological samples with strong UV sources is the damage induced on the irradiated samples. In the present study the effectiveness of a softer UV light for crystal centring by taking advantage of low-power light-emitting diode (LED) sources has been investigated. The use of UV LEDs represents a low-cost solution for crystal centring with high specificity

  3. A comparative study to evaluate the effect of fluoride releasing sealant cured by visible light, argon laers, and light emitting diode curing units: An in vitro study

    Directory of Open Access Journals (Sweden)

    Das U

    2009-09-01

    Full Text Available In Pediatric Dentistry, the use of pit and fissure sealant is one of the essential forms of prevention. Pit and fissure caries may be substantially decreased by obliteration of these developmental defects in occlusal, buccal and lingual surfaces with resin based dental sealants. Visible light-curing units, or LCUs, are an integral part of modern adhesive dentistry" They are used to cure resin based composite restoration materials, resin modified glass-ionomer and pit and fissure sealants, as well as to bond orthodontic teeth. Most recently, the argon laser has been approved for initiating the setting reaction with visible light cured-resins. Argon curing of resin materials has been show to enhance the physical properties and degree of polymerization of the resin, while reducing the polymerization time by 75 percent. The study is undertaken considering the inadequate research reports of regarding the comparison of curing ability using argon laser. LEDs and visible light as well as the resistant towards caries activity of the preventive fluoride releasing pit and fissure sealant cured by above mentioned curing units.

  4. Effects of cement-curing mode and light-curing unit on the bond durability of ceramic cemented to dentin

    Directory of Open Access Journals (Sweden)

    Sheila Pestana Passos

    2013-04-01

    Full Text Available The aim of this study was to evaluate the effects of different light-curing units and resin cement curing types on the bond durability of a feldspathic ceramic bonded to dentin. The crowns of 40 human molars were sectioned, exposing the dentin. Forty ceramic blocks of VITA VM7 were produced according to the manufacturer's recommendations. The ceramic surface was etched with 10% hydrofluoric acid / 60s and silanized. The dentin was treated with 37% phosphoric acid / 15s, and the adhesive was applied. The ceramic blocks were divided and cemented to dentin according to resin cement / RC curing type (dual- and photo-cured, light-curing unit (halogen light / QTH and LED, and storage conditions (dry and storage / 150 days + 12,000 cycles / thermocycling. All blocks were stored in distilled water (37°C / 24h and sectioned (n = 10: G1 - QTH + RC Photo, G2 - QTH + RC Dual, G3 - LED + RC Photo, G4 - LED + RC Dual. Groups G5, G6, G7, and G8 were obtained exactly as G1 through G4, respectively, and then stored and thermocycled. Microtensile bond strength tests were performed (EMIC, and data were statistically analyzed by ANOVA and Tukey's test (5%. The bond strength values (MPa were: G1 - 12.95 (6.40ab; G2 - 12.02 (4.59ab; G3 - 13.09 (5.62ab; G4 - 15.96 (6.32a; G5 - 6.22 (5.90c; G6 - 9.48 (5.99bc; G7 - 12.78 (11.30ab; and G8 - 8.34 (5.98bc. The same superscript letters indicate no significant differences. Different light-curing units affected the bond strength between ceramic cemented to dentin when the photo-cured cement was used, and only after aging (LED > QTH. There was no difference between the effects of dual- and photo-cured resin-luting agents on the microtensile bond strength of the cement used in this study.

  5. Effects of cement-curing mode and light-curing unit on the bond durability of ceramic cemented to dentin.

    Science.gov (United States)

    Passos, Sheila Pestana; Souza, Rodrigo Othávio Assunção; Michida, Silvia Masae Araújo; Zamboni, Sandra Costa; Oliveira, Simone Helena Gonçalves de

    2013-01-01

    The aim of this study was to evaluate the effects of different light-curing units and resin cement curing types on the bond durability of a feldspathic ceramic bonded to dentin. The crowns of 40 human molars were sectioned, exposing the dentin. Forty ceramic blocks of VITA VM7 were produced according to the manufacturer's recommendations. The ceramic surface was etched with 10% hydrofluoric acid / 60s and silanized. The dentin was treated with 37% phosphoric acid / 15s, and the adhesive was applied. The ceramic blocks were divided and cemented to dentin according to resin cement / RC curing type (dual- and photo-cured), light-curing unit (halogen light / QTH and LED), and storage conditions (dry and storage / 150 days + 12,000 cycles / thermocycling). All blocks were stored in distilled water (37°C / 24h) and sectioned (n = 10): G1 - QTH + RC Photo, G2 - QTH + RC Dual, G3 - LED + RC Photo, G4 - LED + RC Dual. Groups G5, G6, G7, and G8 were obtained exactly as G1 through G4, respectively, and then stored and thermocycled. Microtensile bond strength tests were performed (EMIC), and data were statistically analyzed by ANOVA and Tukey's test (5%). The bond strength values (MPa) were: G1 - 12.95 (6.40)ab; G2 - 12.02 (4.59)ab; G3 - 13.09 (5.62)ab; G4 - 15.96 (6.32)a; G5 - 6.22 (5.90)c; G6 - 9.48 (5.99)bc; G7 - 12.78 (11.30)ab; and G8 - 8.34 (5.98)bc. The same superscript letters indicate no significant differences. Different light-curing units affected the bond strength between ceramic cemented to dentin when the photo-cured cement was used, and only after aging (LED > QTH). There was no difference between the effects of dual- and photo-cured resin-luting agents on the microtensile bond strength of the cement used in this study.

  6. Influence of physical assessment of different light-curing units on irradiance and composite microhardness top/bottom ratio.

    Science.gov (United States)

    Morimoto, Susana; Zanini, Renata Aló Maluza; Meira, Josete Barbosa Cruz; Agra, Carlos Martins; Calheiros, Fernanda Calabró; Nagase, Denis Yudi

    2016-09-01

    The aim of this study was to evaluate the influence of the physical assessment of different light-curing units from 55 dental offices on the irradiance and composite microhardness top/bottom ratio, and the influence of the radiometers for LED or QTH light sources on irradiance measurement. The irradiance of each light-curing unit was evaluated with two radiometers, either for LED or QTH light. A questionnaire regarding the type of source (LED or QTH), time of use, date of last maintenance and light-curing performance assessment applied. The physical assessments were evaluated regarding damage or debris on the light tip. For each light-curing unit, three composite specimens were made (diameter = 7 mm; thickness = 2 mm) with polymerizing time of 20 s, in order to perform the microhardness (Knoop) test. Data were analyzed by Kruskal-Wallis and Dunn test (α = 0.01). There was wide variation in irradiance (0-1000 mW/cm(2)). Approximately 50 % of the light-curing units presented radiation lower than 300 mW/cm(2); 10 % of light-curing units, especially those with LED source, presented values higher than 800 mW/cm(2), and 43 % of light-curing units worked with adequate irradiance between 301 and 800 mW/cm(2). In almost 60 % of cases, no maintenance of light-curing units was performed in a period of 3 to 10 years. The age of the light-curing units and the use of inadequate tips interfered negatively in irradiance. The data emphasize the importance of periodic maintenance of light-polymerizing, light-curing units.

  7. Simulation-Based Optimization of Cure Cycle of Large Area Compression Molding for LED Silicone Lens

    Directory of Open Access Journals (Sweden)

    Min-Jae Song

    2015-01-01

    Full Text Available Three-dimensional heat transfer-curing simulation was performed for the curing process by introducing a large area compression molding for simultaneous forming and mass production for the lens and encapsulants in the LED molding process. A dynamic cure kinetics model for the silicone resin was adopted and cure model and analysis result were validated and compared through a temperature measurement experiment for cylinder geometry with cure model. The temperature deviation between each lens cavity could be reduced by implementing a simulation model on the large area compression mold and by optimizing the location of heat source. A two-step cure cycle was constructed to reduce excessive reaction peak at the initial stage and cycle time. An optimum cure cycle that could reduce cycle time by more than 29% compared to a one-step cure cycle by adjusting dwell temperature, heating rate, and dwell time was proposed. It was thus confirmed that an optimization of large area LED lens molding process was possible by using the present experiment and the finite element method.

  8. Effect of new light curing units on microleakage and microhardness of resin sealants.

    Science.gov (United States)

    Bani, Mehmet; Tirali, Resmiye Ebru

    2016-01-01

    To determine new developed light curing units with shorter curing times effects on microleakage and microhardness values for resin fissure sealants. Resin filled sealant (UltraSeal-XT), resin unfilled sealant (Delton Type-II) and ormocer-based sealant (Admira-Seal) were light cured with a quartz-tungsten-halogen (QTH), two LED light and a high power LED. Two hundred and forty extracted human molars were randomly allocated into four groups according to used light-curing unit and three subgroups were formed for three different fissure sealant materials. Specimens were immersed in 0.5% basic fuchsin for 24 h, sectioned and examined under a stereomicroscope, and scored for marginal microleakage. Knoop hardness number (KHN) readings were measured after 48 h. Statistical analyses of test were found in significant difference both microleakage and microhardness values between the various light curing units. The time saving approaches in the curing light were determined higher microhardness, although it was found in higher microleakage.

  9. Dental light curing and its effects on color perception.

    Science.gov (United States)

    McCusker, Neil; Bailey, Clare; Robinson, Stephen; Patel, Naresh; Sandy, Jonathan R; Ireland, Anthony J

    2012-09-01

    Light curing has become increasingly popular for orthodontic bonding, partly as a result of improvements in light-curing unit technology and higher light intensities. The aim of this study was to determine orthodontists' knowledge of dental light-curing units, their safety aspects, and the possible effects on color perception. Questionnaires were administered to 120 specialists or trainees to assess their knowledge of light curing and safety issues. In addition, 15 orthodontists and 15 nonorthodontists were asked to complete the Farnsworth Munsell 100 hue test to assess color perception. One hundred four questionnaires were returned, giving a response rate of 86.6%. Light-emitting diode lights were the most popular (73.4%), followed by quartz-halogen (9.2%) and plasma lights (5.5%); 11.9% were unsure of the type of light used, 84% did not know the intensity, and 67% did not know the wavelength of the lights. Although most used safety equipment-eg, paddles-7% used no safety measures. Seventy-six percent were either unsure or took no precautions during light curing for staff or patients who had previous cataract surgery, and up to 99% were either unsure or took no precautions during light curing for staff or patients taking photosensitizing medications. With the Farnsworth Munsell test, 28 participants had average color discrimination, with 2 demonstrating superior discrimination. There were no differences between the orthodontists and the controls, or between men and women. Orthodontists' knowledge of dental light-curing units and hazards is poor. Although potential risks are associated with the long-term use of these light-curing units, no effect on color discrimination was detected. Copyright © 2012 American Association of Orthodontists. Published by Mosby, Inc. All rights reserved.

  10. UV LED lighting for automated crystal centring.

    Science.gov (United States)

    Chavas, Leonard M G; Yamada, Yusuke; Hiraki, Masahiko; Igarashi, Noriyuki; Matsugaki, Naohiro; Wakatsuki, Soichi

    2011-01-01

    A direct outcome of the exponential growth of macromolecular crystallography is the continuously increasing demand for synchrotron beam time, both from academic and industrial users. As more and more projects entail screening a profusion of sample crystals, fully automated procedures at every level of the experiments are being implemented at all synchrotron facilities. One of the major obstacles to achieving such automation lies in the sample recognition and centring in the X-ray beam. The capacity of UV light to specifically react with aromatic residues present in proteins or with DNA base pairs is at the basis of UV-assisted crystal centring. Although very efficient, a well known side effect of illuminating biological samples with strong UV sources is the damage induced on the irradiated samples. In the present study the effectiveness of a softer UV light for crystal centring by taking advantage of low-power light-emitting diode (LED) sources has been investigated. The use of UV LEDs represents a low-cost solution for crystal centring with high specificity.

  11. [A survey of power density of clinical curing-light units used in Changchun].

    Science.gov (United States)

    Hao, Xin-qing; Luo, Meng; Leng, Xin; Zhu, Song

    2011-09-01

    To investigate the power density and other relevant data of clinical curing-light units used in Changchun, and to provide practice recommendations to clinical dentists about maintaining of cuing-light units. Stomatology hospitals, departments of stomatology in general hospitals, and private dental offices in Changchun were randomly selected to participate in the Survey. The investigation analyzed 270 curing-light units. The following data of curing-light units were gathered: brand, type, operation ages, numbers and types of light guide, resin build-ups on light guides, damages of light guides, use frequency, monitor and maintenance of curing lights, and unit numbers/chair numbers. There were 174 QTH and 96 LED units. The distribution of power density was from 0 to 1702 mW/cm(2). The mean power density was 413.2 mW/cm(2). The power densities of 73 lights were less than 200 mW/cm(2) and could not polymerize resin composites adequately. The mean number of operation age of the light units was 4.74 years. Most of clinical dentists didn't monitor the light-curing units and the situation of build-up from composite resin or damages on light guides was very severe. Most of the light-curing units used in Changchun were QTH. Some QTH units degenerate severely and need to be replaced with the new ones. Most of the clinical doctors lack the knowledge of how to properly monitor and maintain the light-curing units.

  12. The effect of light curing units, curing time, and veneering materials on resin cement microhardness

    OpenAIRE

    Nurcan Ozakar Ilday; Yusuf Ziya Bayindir; Funda Bayindir; Aysel Gurpinar

    2013-01-01

    Background/purpose: Several factors may affects microhardness of resin cement under veneering materials. The aim of this study was to evaluate the effect of different veneering materials, light-curing units and curing times (20/3, 40/6) on the microhardness of dual-cured resin cement. Materials and methods: We pressed dual-cured resin cement specimens (Clearfil SA cement, 5 mm diameter, 1 mm thick) between two microscopic glass slides covered with transparent polystyrene matrix strips to r...

  13. Comparison of curing depth of a colored polyacid-modified composite resin with different light-curing units.

    Science.gov (United States)

    Vandenbulcke, Jeroen D E; Marks, Luc A M; Martens, Luc C; Verbeeck, Ronald M H

    2010-10-01

    To compare the depth of cure (DoC) of a colored polyacid-modified composite resin (PAM-C) with a traditional PAM-C and a fine hybrid composite resin using different light-curing units and different radiant energies. The DoC of the PAM-C Twinky Star (Voco, all shades), the PAM-C Glasiosite (Voco), and the composite resin Z100 (3M ESPE) shades A2 and A4 was determined using a penetrometer test method. The materials were cured in bulk using a halogen-based unit (Elipar Trilight, E = 18 J/cm2 and E = 32 J/cm2; 3M ESPE) and an LED curing unit (Elipar Freelight 2, E = 20 J/cm2; 3M ESPE) in split stainless steel molds. Immediately after curing, the height (mm) of the cured material was measured and taken as the DoC. Ranking of means was performed by Student-Newman-Keuls multiple comparison test, and statistically significant differences among mean values were detected with ANOVA. Mean DoC for all materials and shades varied as follows: 4.705 to 8.870 mm (E = 32 J/cm2); 3.672 to 8.050 mm (E = 20 J/cm2); and 4.090 to 7.357 mm (E = 18 J/cm2). Two-way ANOVA revealed that the DoC depended significantly (P curing device. Moreover, there was a significant interaction (P curing device with the highest energy density exhibited the highest curing depths.

  14. Effect of pre-heating resin composite and light-curing units on monomer conversion

    Science.gov (United States)

    Saade, E. G.; Bandéca, M. C.; Saade, J. L.; Rossato, D. M.; Rastelli, A. N. S.; Bagnato, V. S.; Porto-Neto, S. T.

    2010-01-01

    The purpose of this study was to evaluate the effect of pre-heating resin composite photo-cured with light-curing units (LCU) by FT-IR. Twenty specimens were made in a metallic mold (4 mm diameter × 2 mm thick) from composite resin—Tetric Ceram® (Ivoclar/Vivadent) at room temperature (25°C) and pre-heated to 37, 54, and 60°C. The specimens were cured with halogen curing light (QTH) and light emitted by diodes (LED) during 40 s. Then, the specimens were pulverized, pressed with KBr and analyzed with FT-IR. The data were submitted to statistical analysis of variance and Kruskal-Wallis test. Study data showed no statistically significant difference to the degree of conversion for the different light curing units (QTH and LED) ( p > 0.05). With the increase of temperature there was significant increase in the degree of conversion ( p light curing unit and temperature influenced the degree of conversion.

  15. Comparison of light transmittance in different thicknesses of zirconia under various light curing units.

    Science.gov (United States)

    Cekic-Nagas, Isil; Egilmez, Ferhan; Ergun, Gulfem

    2012-05-01

    The objective of this study was to compare the light transmittance of zirconia in different thicknesses using various light curing units. A total of 21 disc-shaped zirconia specimens (5 mm in diameter) in different thicknesses (0.3, 0.5 and 0.8 mm) were prepared. The light transmittance of the specimens under three different light-curing units (quartz tungsten halogen, light-emitting diodes and plasma arc) was compared by using a hand-held radiometer. Statistical significance was determined using two-way ANOVA (α=.05). ANOVA revealed that thickness of zirconia and light curing unit had significant effects on light transmittance (Plight transmittance. Light-emitting diodes light-curing units might be considered as effective as Plasma arc light-curing units or more effective than Quartz-tungsten-halogen light-curing units for polymerization of the resin-based materials.

  16. Effect of light curing unit on resin-modified glass-ionomer cements: a microhardness assessment

    Directory of Open Access Journals (Sweden)

    Daniela Francisca Gigo Cefaly

    2009-06-01

    Full Text Available OBJECTIVE: To evaluate the microhardness of resin-modified glass-ionomer cements (RMGICs photoactivated with a blue light-emitting diode (LED curing light. MATERIAL AND METHODS: Thirty specimens were distributed in 3 groups: Fuji II LC Improved/GC (RM1, Vitremer/3M ESPE (RM2 and Filtek Z250/ 3M ESPE (RM3. Two commercial light-curing units were used to polymerize the materials: LED/Ultrablue IS and a halogen light/XL3000 (QTH. After 24 h, Knoop microhardness test was performed. Data were submitted to three-way ANOVA and Tukey's test at a pre-set alpha of 0.05. RESULTS: At the top surface, no statistically significant difference (p>0.05 in the microhardness was seen when the LED and QTH lights were used for all materials. At the bottom surface, microhardness mean value of RM2 was significantly higher when the QTH light was used (p0.05 was seen at the bottom surface for RM3, irrespective of the light used. Top-to-bottom surface comparison showed no statistically significant difference (p>0.05 for both RMGICs, regardless of the light used. For RM3, microhardness mean value at the top was significantly higher (p<0.05 than bottom microhardness when both curing units were used. CONCLUSION: The microhardness values seen when a LED light was used varied depending on the restorative material tested.

  17. Influence of the Light Source and Curing Parameters on Microhardness of a Silorane-Based Dental Composite Material

    Directory of Open Access Journals (Sweden)

    Malara P.

    2016-09-01

    Full Text Available The aim of the study was to determine the influence of the light source and the light-curing parameters (the distance of the material from the light source and time of light-curing on microhardness of Flitek Silorane dental composite material. Standardized samples of Filtek Silorane material were cured using two types of Light Curing Units (LCUs – halogen and LED. The distance of the light source and time of curing differed between samples. The Knoop’s microhardness was tested using microhardness tester Micromet 5103. Using LED light curing unit allowed to achieve significantly higher microhardness of silorane-based dental material Filtek Silorane than using halogen light curing unit. Decreasing the distance from the light source to the surface of silorane-based material Filtek Silorane improved its microhardness. A prolonged curing time could compensate the drop in microhardness of Filtek Silorane material resulting from an increased distance from the light source to the surface of the material only in a limited range of intervals.

  18. Influence of light-curing units and restorative materials on the micro hardness of resin cements

    Directory of Open Access Journals (Sweden)

    Kuguimiya Rosiane

    2010-01-01

    Full Text Available Aim: The aim of this study was to evaluate the effect of indirect restorative materials (IRMs and light-curing units (LCUs on the micro hardness of dual-cured resin cement. Materials and Methods: A total of 36 cylindrical samples (2 mm thick were prepared with dual-cured resin cement (Relyx ARC photo-activated with either a QTH (Optilight Plus for 40s or a LED (Radii light-curing unit for 65s. Photo-activation was performed through the 2-mm- thick IRMs and the samples were divided into six groups (n=6 according to the combination of veneering materials (without, ceramic and indirect resin and LCUs (QTH and LED. In the control group, the samples were light-cured with a QTH unit without the interposition of any restorative material. Vickers micro hardness test was performed on the top and bottom surfaces of each sample (load of 50 g for 15 secs. The data were statistically analyzed using a three-way ANOVA followed by Tukey x s post-hoc test ( P < 0.05. Results: There were no statistically significant differences on the top surface between the light curing-units ( P > 0.05; however, the LED provided greater hardness on the bottom surface when a ceramic material was used ( P < 0.05. The mean hardness in photo-activated samples, in which there was no interposition of indirect materials, was significantly greater ( P < 0.01. Conclusions: It may be concluded that the interposition of the restorative material decreased the micro hardness in the deeper cement layer. Such decrease, however, was lower when the ceramic was interposed and the cement light-cured with LED.

  19. Influence of Curing Light Attenuation Caused by Aesthetic Indirect Restorative Materials on Resin Cement Polymerization

    Science.gov (United States)

    Pick, Bárbara; Gonzaga, Carla Castiglia; Junior, Washington Steagall; Kawano, Yoshio; Braga, Roberto Ruggiero; Cardoso, Paulo Eduardo Capel

    2010-01-01

    Objectives: To verify the effect of interposing different indirect restorative materials on degree of conversion (DC), hardness, and flexural strength of a dual-cure resin cement. Methods: Discs (2 mm-thick, n=5) of four indirect restorative materials were manufactured: a layered glass-ceramic (GC); a heat-pressed lithium disilicate-based glass-ceramic veneered with the layered glass-ceramic (LD); a micro-hybrid (MH); and a micro-filled (MF) indirect composite resin. The light transmittance of these materials was determined using a double-beam spectrophotometer with an integrating sphere. Bar-shaped specimens of a dual-cure resin cement (Nexus 2/SDS Kerr), with (dual-cure mode) and without the catalyst paste (light-cure mode), were photoactivated through the discs using either a quartz-tungsten-halogen (QTH) or a light-emitting diode (LED) unit. As a control, specimens were photoactivated without the interposed discs. Specimens were stored at 37ºC for 24h before being submitted to FT-Raman spectrometry (n=3), Knoop microhardness (n=6) and three-point bending (n=6) tests. Data were analyzed by ANOVA/Tukey’s test (α=0.05). Results: MH presented the highest transmittance. The DC was lower in light-cure mode than in dual-cure mode. All restorative materials reduced the cement microhardness in light-cure mode. GC and LD with QTH and GC with LED decreased the strength of the cement for both activation modes compared to the controls. Curing units did not affect DC or microhardness, except when the dual-cure cement was photoactivated through LD (LED>QTH). Flexural strength was higher with QTH compared to LED. Conclusions: Differences in transmittance among the restorative materials significantly influenced cement DC and flexural strength, regardless of the activation mode, as well as the microhardness of the resin cement tested in light-cure mode. Microhardness was not impaired by the interposed materials when the resin cement was used in dual-cure mode. PMID:20613921

  20. Efficiency of light curing units in a government dental school.

    Science.gov (United States)

    Nassar, Hani M; Ajaj, Reem; Hasanain, Fatin

    2018-01-01

    The light intensity of a light-curing unit is a crucial factor that affects the clinical longevity of resin composites. This study aimed to investigate the efficiency of light-curing units in use at a local governmental dental school for curing conventional and bulk-fill resin materials. A total of 166 light-curing units at three locations were examined, and the brand, type, clinic location, diameter of curing tip, tip cleanliness (using a visual score), and the output (in mW/cm 2 using a digital radiometer) were recorded. Only 23.5% of the units examined had clean tips, with the graduate student clinical area containing the highest percentage of clean tips. Further, tips with poor cleanliness score values were associated with significantly lower output intensities. A small percentage (9.4%) of units was capable of producing intensities higher than 1,200 mW/cm 2 and lower than 600 mW/cm 2 (7.6%). The majority of the low intensity units were located in the undergraduate student area, which also contained the highest number of units with intensities between 900 and 1,200 mW/cm 2 . The output of all the units in service was satisfactory for curing conventional resin composites, and most units were capable of curing bulk-fill resin materials.

  1. Effect of light curing protocol on degree of conversion of composites.

    Science.gov (United States)

    Catelan, Anderson; Mainardi, Maria do Carmo Aguiar Jordão; Soares, Giulliana Panfiglio; de Lima, Adriano Fonseca; Ambrosano, Gláucia Maria Bovi; Lima, Débora Alves Nunes Leite; Marchi, Giselle Maria; Aguiar, Flávio Henrique Baggio

    2014-11-01

    To evaluate the degree of conversion (DC) of two light-cured composites with different protocols of light curing. One hundred and ninety two specimens (n = 8) were prepared (5 mm × 2 mm) according to experimental groups: two composite resins (Filtek Supreme and four seasons); three light curing protocols [20 s with the tip of the light curing unit (LCU) device touching composite surface (C); 20 s with the tip of the LCU at 8 mm distant from composite surface (D); and tip of the LCU at 8 mm distant from composite surface and polymerization time required to obtain a radiant exposure of 16 J/cm(2) (DS)]. Four LCUs (Bluephase 16i, Ultralume LED 5, XL 3000 and Optilux 501C) were used. DC of the bottom and top surface of specimens were measured using a FTIR spectrometer. Data were statistically analyzed by 3-way split splot ANOVA and Tukey's test (alpha = 0.05). The results showed that DC of the top surface was higher than the bottom at all experimental conditions (p curing at 8 mm of distance did not affect conversion rate on the top surface (p > 0.05), but bottom surfaces showed DC reduction (p curing units with higher light power and/or extended exposure time.

  2. Curing kinetics of visible light curing dental resin composites investigated by dielectric analysis (DEA).

    Science.gov (United States)

    Steinhaus, Johannes; Hausnerova, Berenika; Haenel, Thomas; Großgarten, Mandy; Möginger, Bernhard

    2014-03-01

    During the curing process of light curing dental composites the mobility of molecules and molecule segments is reduced leading to a significant increase of the viscosity as well as the ion viscosity. Thus, the kinetics of the curing behavior of 6 different composites was derived from dielectric analysis (DEA) using especially redesigned flat sensors with interdigit comb electrodes allowing for irradiation at the top side and measuring the ion viscosity at the bottom side. As the ion viscosities of dental composites change 1-3 orders of magnitude during the curing process, DEA provides a sensitive approach to evaluate their curing behavior, especially in the phase of undisturbed chain growth. In order to determine quantitative kinetic parameters a kinetic model is presented and examined for the evaluation of the ion viscosity curves. From the obtained results it is seen that DEA might be employed in the investigation of the primary curing process, the quality assurance of ingredients as well as the control of processing stability of the light curing dental composites. Copyright © 2014 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  3. Current status of visible light activation units and the curing of light-activated resin-based composite materials.

    Science.gov (United States)

    Santini, Ario

    2010-05-01

    Light activation units are standard items of equipment in dental practice. It is essential to understand the many factors which affect the polymerization of light-activated resin composite materials and the choice of a light curing unit. In this respect, the development of high-intensity halogen and light-emitting diode (LED) light curing units (LCUs), many with multiple curing modes, has revolutionized light curing techniques. This article reviews visible light activation unit design and development. Factors influencing the effective use of LCUs and polymerization of resin-based composite materials are discussed, as are the steps which should be taken to maintain the efficiency of units in clinical use. Many LCUs produce lower output intensities than stated by the manufacturer. Newer high power LEDs may present as much of a heat problem as high power quartz tungsten halogen lamps (QTHs).The manufacturer's data should be followed to ensure that the emission spectra of the unit is compatible with the photo-initiator in the resin-based composite material.

  4. Effect of Dental Chair Light on Enamel Bonding of Orthodontic Brackets Using Light Cure Based Adhesive System: An In-Vitro Study.

    Science.gov (United States)

    Tiwari, Anil; Shyagali, Tarulatha; Kohli, Sarvraj; Joshi, Rishi; Gupta, Abhishek; Tiwari, Rana

    2016-10-01

    The aim of this in vitro study was to evaluate the influence of the Dental chair light on the bond strength of light cured composite resin. Sixty therapeutically extracted human premolar teeth were randomly allocated to two groups of 30 specimens each. In both groups light cured composite resin (Transbond XT) and MBT premolar metal brackets (3M Unitek) was used to bond brackets. In group I and II light curing was done using Light-emitting diode light curing units without and with the dental chair light respectively. After bonding, all samples were stored in distilled water at room temperature for 24 hours and subsequently tested for shear bond strength and Adhesive Remnant Index (ARI) scores. Data was subjected to Mann Whitney U statistical test. Results indicated that there was significantly higher shear bond strength (7.71 ± 1.90) for the Group II (composite cured with LED and dental chair light) compared with Group I (composite cured with LED LCU only) (5.74 ± 1.13).the obtained difference was statistically significant. There was no statistical significant difference between ARI scores in between the groups. light cure bonding with dental chair light switched on will produce greater bond strength than the conventional bonding. However, the ARI score were similar to both the groups. It is advised that the inexperienced orthodontist should always switch off the dental chair light while bonding for enough working time during the bracket placement.

  5. Use of light-curing units in orthodontics.

    Science.gov (United States)

    Goyal, Amit; Hurkadle, Jyothikiran; Magegowda, Shivalinga; Bhatia, Pankaj

    2013-08-01

    Because of their wide field of applications, light-curing units are now indispensable for orthodontists and general dentists; thus, it is important to be familiar with the various types of light-curing units, their history, specifications, advantages, and disadvantages. For this review, a search of the PubMed database (from 1966 to March 2010) was conducted using the search term "curing lights orthodontics". Eligibility of the selected studies was determined by reading the abstracts of articles identified by the search. All the articles that met the inclusion criteria were selected, and the articles collected. The reference lists of the retrieved articles were also hand searched for any applicable studies that might have been missed in the database searches. When selecting curing lights for an office, many variables need to be considered. Armed with knowledge about each curing-light category, orthodontists can evaluate their unique practice style and select the appropriate light/lights. © 2013 Wiley Publishing Asia Pty Ltd.

  6. Effect of High-Irradiance Light-Curing on Micromechanical Properties of Resin Cements.

    Science.gov (United States)

    Peutzfeldt, Anne; Lussi, Adrian; Flury, Simon

    2016-01-01

    This study investigated the influence of light-curing at high irradiances on micromechanical properties of resin cements. Three dual-curing resin cements and a light-curing flowable resin composite were light-cured with an LED curing unit in Standard mode (SM), High Power mode (HPM), or Xtra Power mode (XPM). Maximum irradiances were determined using a MARC PS radiometer, and exposure duration was varied to obtain two or three levels of radiant exposure (SM: 13.2 and 27.2 J/cm 2 ; HPM: 15.0 and 30.4 J/cm 2 ; XPM: 9.5, 19.3, and 29.7 J/cm 2 ) ( n = 17). Vickers hardness ( H V ) and indentation modulus ( E IT ) were measured at 15 min and 1 week. Data were analyzed with nonparametric ANOVA, Wilcoxon-Mann-Whitney tests, and Spearman correlation analyses ( α = 0.05). Irradiation protocol, resin-based material, and storage time and all interactions influenced H V and E IT significantly ( p ≤ 0.0001). Statistically significant correlations between radiant exposure and H V or E IT were found, indicating that high-irradiance light-curing has no detrimental effect on the polymerization of resin-based materials ( p ≤ 0.0021). However, one resin cement was sensitive to the combination of irradiance and exposure duration, with high-irradiance light-curing resulting in a 20% drop in micromechanical properties. The results highlight the importance of manufacturers issuing specific recommendations for the light-curing procedure of each resin cement.

  7. Effect of High-Irradiance Light-Curing on Micromechanical Properties of Resin Cements

    Directory of Open Access Journals (Sweden)

    Anne Peutzfeldt

    2016-01-01

    Full Text Available This study investigated the influence of light-curing at high irradiances on micromechanical properties of resin cements. Three dual-curing resin cements and a light-curing flowable resin composite were light-cured with an LED curing unit in Standard mode (SM, High Power mode (HPM, or Xtra Power mode (XPM. Maximum irradiances were determined using a MARC PS radiometer, and exposure duration was varied to obtain two or three levels of radiant exposure (SM: 13.2 and 27.2 J/cm2; HPM: 15.0 and 30.4 J/cm2; XPM: 9.5, 19.3, and 29.7 J/cm2 (n=17. Vickers hardness (HV and indentation modulus (EIT were measured at 15 min and 1 week. Data were analyzed with nonparametric ANOVA, Wilcoxon-Mann-Whitney tests, and Spearman correlation analyses (α=0.05. Irradiation protocol, resin-based material, and storage time and all interactions influenced HV and EIT significantly (p≤0.0001. Statistically significant correlations between radiant exposure and HV or EIT were found, indicating that high-irradiance light-curing has no detrimental effect on the polymerization of resin-based materials (p≤0.0021. However, one resin cement was sensitive to the combination of irradiance and exposure duration, with high-irradiance light-curing resulting in a 20% drop in micromechanical properties. The results highlight the importance of manufacturers issuing specific recommendations for the light-curing procedure of each resin cement.

  8. EFFECT OF LIGHT CURING UNIT CHARACTERISTICS ON LIGHT INTENSITY OUTPUT, DEPTH OF CURE AND SURFACE MICRO-HARDNESS OF DENTAL RESIN COMPOSITE.

    Science.gov (United States)

    Kassim, B A; Kisumbi, B K; Lesan, W R; Gathece, L W

    2013-09-01

    Modern dental composite restorations are wholly dependent on the use of Visible Light Curing devices. The characteristics of these devices may influence the quality of composite resin restorations. To determine the characteristics of light curing units (LCUs) in dental clinics in Nairobi and their effect on light intensity output, depth of cure (DOC) and surface micro-hardness (SMH) of dental resin composite. Laboratory based, cross-sectional analytical study. Public and private dental clinics in Nairobi, Kenya. Eighty three LCUs which were in use in private and public dental health facilities in Nairobi, Kenya and resin composite specimens. Of the 83 LCUs studied, 43 (51.8%) were Light Emitting Diodes (LEDs) and 39(47.0%) were Quartz-Tungsten-Halogen (QTH) and 1 (1.2%) was Plasma Arc Curing (PAC) light. Mean light intensity for QTH and LED lights was 526.59 mW/cm2 and 493.67 mW/cm2 respectively (p=0.574), while the mean DOC for QTH lights was 1.71 mm and LED was 1.67 mm (p=0.690). Mean Vickers Hardness Number (VHN) for LED was 57.44 and for QTH was 44.14 (p=0.713). Mean light intensity for LCUs units > 5 years old (p=0.024). The mean DOC for the two age groups was 1.74 mm and 1.57 mm respectively (p=0.073). For SMH, the 5 years age groups gave a mean VHN of 58.81 and 51.46 respectively (p=0.1). On maintenance history, the frequency of routine inspection, duration since the last repair/replacement of a part or other maintenance activity and the nature of the last maintenance activity were determined and were not found to have influenced the light intensity, DOC and SMH. The LCU age has a statistically significant influence on its light intensity (p=0.024) while the type and maintenance history have no significant influence on its light intensity and composite DOC and SMH (p=0.574, p=0.690, p=0.713 respectively).

  9. Effect of light curing unit on resin-modified glass-ionomer cements: a microhardness assessment.

    Science.gov (United States)

    Cefaly, Daniela Francisca Gigo; de Mello, Liliam Lucia Carrara Paes; Wang, Linda; Lauris, José Roberto Pereira; D'Alpino, Paulo Henrique Perlatti

    2009-01-01

    To evaluate the microhardness of resin-modified glass-ionomer cements (RMGICs) photoactivated with a blue light-emitting diode (LED) curing light. Thirty specimens were distributed in 3 groups: Fuji II LC Improved/GC (RM1), Vitremer/3M ESPE (RM2) and Filtek Z250/3M ESPE (RM3). Two commercial light-curing units were used to polymerize the materials: LED/Ultrablue IS and a halogen light/XL3000 (QTH). After 24 h, Knoop microhardness test was performed. Data were submitted to three-way ANOVA and Tukey's test at a pre-set alpha of 0.05. At the top surface, no statistically significant difference (p>0.05) in the microhardness was seen when the LED and QTH lights were used for all materials. At the bottom surface, microhardness mean value of RM2 was significantly higher when the QTH light was used (plight was used. No statistically significant difference (p>0.05) was seen at the bottom surface for RM3, irrespective of the light used. Top-to-bottom surface comparison showed no statistically significant difference (p>0.05) for both RMGICs, regardless of the light used. For RM3, microhardness mean value at the top was significantly higher (pcuring units were used. The microhardness values seen when a LED light was used varied depending on the restorative material tested.

  10. The effects of Exposure Times and Light Curing Sources on Surface Micro-Hardness of a Resin Modified Glass Ionomer

    Directory of Open Access Journals (Sweden)

    Iman Parisay

    2014-06-01

    Full Text Available Introduction: The aim of this study was to evaluate the influenceof different light curing systems and curing times on the micro-hardness of aresin modified glass ionomer. Methods: Forty two samples of ResinModified Glass Ionomer (RMGI were prepared using stainless steel cylindrical mold(8 × 2 mm and randomly divided into six groups of seven. Three groups werecured with a Quartz Tungsten Halogen (QTH light cure unit and the other threegroups were polymerized with LED unit for 20, 30 and 40 seconds. All sampleswere stored in distilled water for 24 hours. The micro-hardness was measured onthe top and bottom surfaces of the samples by Vickers hardness tester. Datawere analyzed by two–way ANOVA and Tukey’s post-hoc tests. Results: Two-wayANOVA showed that QTH light-cure unit had higher percentage in depth of curethan LED light-curing unit in both surfaces; whereas, the application time hasno significant effect on it. There was no interaction between two variables. Inboth light-curing groups, the values of top and bottom surfaces micro-hardnesswere increased as the application time increased, but there was not anystatistically significant difference among these groups except for 40-second groupof LED light-curing unit which was significantly higher than 20-second and30-second groups (P

  11. A novel amblyopia treatment system based on LED light source

    Science.gov (United States)

    Zhang, Xiaoqing; Chen, Qingshan; Wang, Xiaoling

    2011-05-01

    A novel LED (light emitting diode) light source of five different colors (white, red, green, blue and yellow) is adopted instead of conventional incandescent lamps for an amblyopia treatment system and seven training methods for rectifying amblyopia are incorporated so as for achieving an integrated therapy. The LED light source is designed to provide uniform illumination, adjustable light intensity and alterable colors. Experimental tests indicate that the LED light source operates steadily and fulfills the technical demand of amblyopia treatment.

  12. Temperature rise induced by various light curing units through human dentin.

    Science.gov (United States)

    Dogan, Arife; Hubbezoglu, Ihsan; Dogan, Orhan Murat; Bolayir, Giray; Demir, Hakan

    2009-05-01

    This study investigated temperature rises caused by different light curing units (LCUs) in dentin of different thicknesses. The different LCUs tested in this study were namely: quartz-tungsten-halogen (QTH) (Heliolux DLX) LCU, plasma arc (PAC) (Apollo 95E Elite) LCU, and light emitting diode (LED) (Mini LED) in standard curing mode as well as pulse and soft-start modes. One hundred and forty dentin disks of 0.5, 1, 1.5, and 2 mm thickness were prepared from mandibular molars (n=7). Temperatures were recorded using a L-type thermocouple in direct contact with the light guide tip. For all curing units/modes, dentin thickness was inversely proportional to temperature rise and that QTH light gave significantly higher values compared to PAC and LED in all the test conditions. The highest temperature rise was observed under 0.5-mm-thick dentin disk with QTH, whereas the lowest temperature rise was registered with LED light in pulse mode under 2-mm-thick dentin.

  13. Surface energy and wettability of polymers light-cured by two different systems.

    Science.gov (United States)

    Namen, Fatima Maria; Ferrandini, Eduardo; Galan Junior, João

    2011-10-01

    This study evaluated the surface energy and wettability of composite resins polymerized by different light-curing units to ascertain the good wetting of tooth surfaces to achieve adhesion. Filtek Z350 (3M ESPE), Admira (VOCO) and Grandio (VOCO) resins were selected for the testing procedures. The resins were light cured using LED and Halogen devices. Contact angles were measured goniometrically (Ramé-Hart F100) using water and glycerol as test liquids. Surface energy values were calculated with a software program (DROPimage Standard) that uses the harmonic mean method applied to the acid-base theory. The data were analyzed statistically by ANOVA and Tukey's test with a significance of 0.05. No statistically significant differences were found between the values of surface energy. The measured wettability differed statistically in most combinations as a function of the type of composite resin, type of light-curing unit, and the test liquid.

  14. Thermal analysis of bulk filled composite resin polymerization using various light curing modes according to the curing depth and approximation to the cavity wall

    Directory of Open Access Journals (Sweden)

    Hoon-Sang Chang

    2013-07-01

    Full Text Available OBJECTIVE: The purpose of this study was to investigate the polymerization temperature of a bulk filled composite resin light-activated with various light curing modes using infrared thermography according to the curing depth and approximation to the cavity wall. MATERIAL AND METHODS: Composite resin (AeliteFlo, Bisco, Schaumburg, IL, USA was inserted into a Class II cavity prepared in the Teflon blocks and was cured with a LED light curing unit (Dr's Light, GoodDoctors Co., Seoul, Korea using various light curing modes for 20 s. Polymerization temperature was measured with an infrared thermographic camera (Thermovision 900 SW/TE, Agema Infra-red Systems AB, Danderyd, Sweden for 40 s at measurement spots adjacent to the cavity wall and in the middle of the cavity from the surface to a 4 mm depth. Data were analyzed according to the light curing modes with one-way ANOVA, and according to curing depth and approximation to the cavity wall with two-way ANOVA. RESULTS: The peak polymerization temperature of the composite resin was not affected by the light curing modes. According to the curing depth, the peak polymerization temperature at the depth of 1 mm to 3 mm was significantly higher than that at the depth of 4 mm, and on the surface. The peak polymerization temperature of the spots in the middle of the cavity was higher than that measured in spots adjacent to the cavity wall. CONCLUSION: In the photopolymerization of the composite resin, the temperature was higher in the middle of the cavity compared to the outer surface or at the internal walls of the prepared cavity.

  15. Thermal analysis of bulk filled composite resin polymerization using various light curing modes according to the curing depth and approximation to the cavity wall.

    Science.gov (United States)

    Chang, Hoon-Sang; Cho, Kyu-Jeong; Park, Su-Jung; Lee, Bin-Na; Hwang, Yun-Chan; Oh, Won-Mann; Hwang, In-Nam

    2013-01-01

    The purpose of this study was to investigate the polymerization temperature of a bulk filled composite resin light-activated with various light curing modes using infrared thermography according to the curing depth and approximation to the cavity wall. Composite resin (AeliteFlo, Bisco, Schaumburg, IL, USA) was inserted into a Class II cavity prepared in the Teflon blocks and was cured with a LED light curing unit (Dr's Light, GoodDoctors Co., Seoul, Korea) using various light curing modes for 20 s. Polymerization temperature was measured with an infrared thermographic camera (Thermovision 900 SW/TE, Agema Infra-red Systems AB, Danderyd, Sweden) for 40 s at measurement spots adjacent to the cavity wall and in the middle of the cavity from the surface to a 4 mm depth. Data were analyzed according to the light curing modes with one-way ANOVA, and according to curing depth and approximation to the cavity wall with two-way ANOVA. The peak polymerization temperature of the composite resin was not affected by the light curing modes. According to the curing depth, the peak polymerization temperature at the depth of 1 mm to 3 mm was significantly higher than that at the depth of 4 mm, and on the surface. The peak polymerization temperature of the spots in the middle of the cavity was higher than that measured in spots adjacent to the cavity wall. In the photopolymerization of the composite resin, the temperature was higher in the middle of the cavity compared to the outer surface or at the internal walls of the prepared cavity.

  16. The Effect of Irradiation Distance on Microhardness of Resin Composites Cured with Different Light Curing Units

    Science.gov (United States)

    Cekic-Nagas, Isil; Egilmez, Ferhan; Ergun, Gulfem

    2010-01-01

    Objectives: The aim of this study was to compare the microhardness of five different resin composites at different irradiation distances (2 mm and 9 mm) by using three light curing units (quartz tungsten halogen, light emitting diodes and plasma arc). Methods: A total of 210 disc-shaped samples (2 mm height and 6 mm diameter) were prepared from different resin composites (Simile, Aelite Aesthetic Enamel, Clearfil AP-X, Grandio caps and Filtek Z250). Photoactivation was performed by using quartz tungsten halogen, light emitting diode and plasma arc curing units at two irradiation distances (2 mm and 9 mm). Then the samples (n=7/per group) were stored dry in dark at 37°C for 24 h. The Vickers hardness test was performed on the resin composite layer with a microhardness tester (Shimadzu HMV). Data were statistically analyzed using nonparametric Kruskal Wallis and Mann-Whitney U tests. Results: Statistical analysis revealed that the resin composite groups, the type of the light curing units and the irradiation distances have significant effects on the microhardness values (P<.05). Conclusions: Light curing unit and irradiation distance are important factors to be considered for obtaining adequate microhardness of different resin composite groups. PMID:20922164

  17. Solid State Lighting LED Manufacturing Roundtable Summary

    Energy Technology Data Exchange (ETDEWEB)

    none,

    2010-03-31

    Summary of a meeting of LED experts to develop proposed priority tasks for the Manufacturing R&D initiative, including task descriptions, discussion points, recommendations, and presentation highlights.

  18. Comparison of the bonding strengths of second- and third-generation light-emitting diode light-curing units.

    Science.gov (United States)

    Lee, Hee-Min; Kim, Sang-Cheol; Kang, Kyung-Hwa; Chang, Na-Young

    2016-11-01

    With the introduction of third-generation light-emitting diodes (LEDs) in dental practice, it is necessary to compare their bracket-bonding effects, safety, and efficacy with those of the second-generation units. In this study, 80 extracted human premolars were randomly divided into eight groups of 10 samples each. Metal or polycrystalline ceramic brackets were bonded on the teeth using second- or third-generation LED light-curing units (LCUs), according to the manufacturers' instructions. The shear bond strengths were measured using the universal testing machine, and the adhesive remnant index (ARI) was scored by assessing the residual resin on the surfaces of debonded teeth using a scanning electron microscope. In addition, curing times were also measured. The shear bond strengths in all experimental groups were higher than the acceptable clinical shear bond strengths, regardless of the curing unit used. In both LED LCU groups, all ceramic bracket groups showed significantly higher shear bond strengths than did the metal bracket groups except the plasma emulation group which showed no significant difference. When comparing units within the same bracket type, no differences in shear bond strength were observed between the second- and third-generation unit groups. Additionally, no significant differences were observed among the groups for the ARI. The bracket-bonding effects and ARIs of second- and third-generation LED LCUs showed few differences, and most were without statistical significance; however, the curing time was shorter for the second-generation unit.

  19. Integrated LED-based luminaire for general lighting

    Science.gov (United States)

    Dowling, Kevin J.; Lys, Ihor A.; Williamson, Ryan C.; Roberge, Brian; Roberts, Ron; Morgan, Frederick; Datta, Michael Jay; Mollnow, Tomas Jonathan

    2016-08-30

    Lighting apparatus and methods employing LED light sources are described. The LED light sources are integrated with other components in the form of a luminaire or other general purpose lighting structure. Some of the lighting structures are formed as Parabolic Aluminum Reflector (PAR) luminaires, allowing them to be inserted into conventional sockets. The lighting structures display beneficial operating characteristics, such as efficient operation, high thermal dissipation, high output, and good color mixing.

  20. Integrated LED-based luminare for general lighting

    Science.gov (United States)

    Dowling, Kevin J.; Lys, Ihor A.; Roberge, Brian; Williamson, Ryan C.; Roberts, Ron; Datta, Michael; Mollnow, Tomas; Morgan, Frederick M.

    2013-03-05

    Lighting apparatus and methods employing LED light sources are described. The LED light sources are integrated with other components in the form of a luminaire or other general purpose lighting structure. Some of the lighting structures are formed as Parabolic Aluminum Reflector (PAR) luminaires, allowing them to be inserted into conventional sockets. The lighting structures display beneficial operating characteristics, such as efficient operation, high thermal dissipation, high output, and good color mixing.

  1. Photothermal radiometry monitoring of light curing in resins

    Science.gov (United States)

    Zambrano-Arjona, M. A.; Medina-Esquivel, R.; Alvarado-Gil, J. J.

    2007-10-01

    Real time measurement of thermal diffusivity during the evolution of the light curing process in dental resins is reported using photothermal radiometry. The curing is induced by a non-modulated blue light beam, and at the same time, a modulated red laser beam is sent onto the sample, generating a train of thermal waves that produce modulated infrared radiation. The monitoring of this radiation permits to follow the time evolution of the process. The methodology is applied to two different commercially available light curing resin-based composites. In all cases thermal diffusivity follows a first order kinetics with similar stabilization characteristic times. Analysis of this kinetics permits to exhibit the close relationship of increase in thermal diffusivity with the decrease in monomer concentration and extension of the polymerization in the resin, induced by the curing light. It is also shown that the configuration in which the resin is illuminated by the modulated laser can be the basis for the development of an in situ technique for the determination of the degree of curing.

  2. Kansas highway LED illumination manual : a guide for the use of LED lighting systems.

    Science.gov (United States)

    2015-12-01

    The research project was aimed to assist the Kansas Department of Transportation (KDOT) in the development of a Highway LED Illumination Manual for guiding the upcoming implementation of successful LED roadway lighting systems in Kansas to replace th...

  3. Kansas highway LED illumination manual : a guide for the use of LED lighting systems : [technical summary].

    Science.gov (United States)

    2015-12-01

    The research project was aimed to assist the Kansas Department of Transportation (KDOT) in the development of a Highway LED Illumination Manual for guiding the upcoming implementation of successful LED roadway lighting systems in Kansas to replace th...

  4. Mechanical properties and polymerization shrinkage of composite resins light-cured using two different lasers.

    Science.gov (United States)

    Kim, Tae-Wan; Lee, Jang-Hoon; Jeong, Seung-Hwa; Ko, Ching-Chang; Kim, Hyung-Il; Kwon, Yong Hoon

    2015-04-01

    The purpose of the present study was to investigate the usefulness of 457 and 473 nm lasers for the curing of composite resins during the restoration of damaged tooth cavity. Monochromaticity and coherence are attractive features of laser compared with most other light sources. Better polymerization of composite resins can be expected. Eight composite resins were light cured using these two lasers and a light-emitting diode (LED) light-curing unit (LCU). To evaluate the degrees of polymerization achieved, polymerization shrinkage and flexural and compressive properties were measured and compared. Polymerization shrinkage values by 457 and 473 nm laser, and LED ranged from 10.9 to 26.8, from 13.2 to 26.1, and from 11.5 to 26.3 μm, respectively. The values by 457 nm laser was significantly different from those by 473 and LED LCU (p0.05). For the tested LCUs, no specific LCU could consistently achieve highest strength and modulus from the specimens tested. Two lasers (457 and 473 nm) can polymerize composite resins to the level that LED LCU can achieve despite inconsistent trends of polymerization shrinkage and flexural and compressive properties of the tested specimens.

  5. Effect of reduced exposure times on the cytotoxicity of resin luting cements cured by high-power led

    Directory of Open Access Journals (Sweden)

    Gulfem Ergun

    2011-06-01

    Full Text Available OBJECTIVE: Applications of resin luting agents and high-power light-emitting diodes (LED light-curing units (LCUs have increased considerably over the last few years. However, it is not clear whether the effect of reduced exposure time on cytotoxicity of such products have adequate biocompatibility to meet clinical success. This study aimed at assessing the effect of reduced curing time of five resin luting cements (RLCs polymerized by high-power LED curing unit on the viability of a cell of L-929 fibroblast cells. MATERIAL AND METHODS: Disc-shaped samples were prepared in polytetrafluoroethylene moulds with cylindrical cavities. The samples were irradiated from the top through the ceramic discs and acetate strips using LED LCU for 20 s (50% of the manufacturer's recommended exposure time and 40 s (100% exposure time. After curing, the samples were transferred into a culture medium for 24 h. The eluates were obtained and pipetted onto L-929 fibroblast cultures (3x10(4 per well and incubated for evaluating after 24 h. Measurements were performed by dimethylthiazol diphenyltetrazolium assay. Statistical significance was determined by two-way ANOVA and two independent samples were compared by t-test. RESULTS: Results showed that eluates of most of the materials polymerized for 20 s (except Rely X Unicem and Illusion reduced to a higher extent cell viability compared to samples of the same materials polymerized for 40 s. Illusion exhibited the least cytotoxicity for 20 s exposure time compared to the control (culture without samples followed by Rely X Unicem and Rely X ARC (90.81%, 88.90%, and 83.11%, respectively. For Rely X ARC, Duolink and Lute-It 40 s exposure time was better (t=-1.262 p=0,276; t=-9.399 p=0.001; and t=-20.418 p<0.001, respectively. CONCLUSION: The results of this study suggest that reduction of curing time significantly enhances the cytotoxicity of the studied resin cement materials, therefore compromising their clinical

  6. Development of Wireless Dimming Control System for LED Stage Light

    OpenAIRE

    Wang Hui Qin; Bai Shi Lei

    2016-01-01

    Compared with the existing wire dimming system of LED stage light which uses the heavy light operating console to adjust the brightness of stage light, a portable wireless dimming control system for LED stage lighting is proposed, fabricated and tested in this paper. The scheme with the core of ATmega16L microcontroller is composed of wireless transmission and reception units, constant current driving circuit of LED, and the control circuit between this two modules. Through the system present...

  7. Influence of curing protocol on selected properties of light-curing polymers

    DEFF Research Database (Denmark)

    Dewaele, Magali; Asmussen, Erik; Peutzfeldt, Anne

    2009-01-01

    The purpose of this study was to investigate the effect of light-curing protocol on degree of conversion (DC), volume contraction (C), elastic modulus (E), and glass transition temperature (T(g)) as measured on a model polymer. It was a further aim to correlate the measured values with each other....

  8. The dental curing light: A potential health risk.

    Science.gov (United States)

    Price, Richard B T; Labrie, Daniel; Bruzell, Ellen M; Sliney, David H; Strassler, Howard E

    2016-08-01

    Powerful blue-light emitting dental curing lights are used in dental offices to photocure resins in the mouth. In addition, many dental personnel use magnification loupes. This study measured the effect of magnification loupes on the "blue light hazard" when the light from a dental curing light was reflected off a human tooth. Loupes with 3.5x magnification (Design for Vision, Carl Zeiss, and Quality Aspirator) and 2.5x magnification (Design for Vision and Quality Aspirator) were placed at the entrance of an integrating sphere connected to a spectrometer (USB 4000, Ocean Optics). A model with human teeth was placed 40 cm away and in line with this sphere. The light guide tip of a broad-spectrum Sapphire Plus (Den-Mat) curing light was positioned at a 45° angle from the facial surface of the central incisor. The spectral radiant power reflected from the teeth was recorded five times with the loupes over the entrance into the sphere. The maximum permissible cumulative exposure times in an 8-hr day were calculated using guidelines set by the ACGIH. It was concluded that at a 40 cm distance, the maximum permissible cumulative daily exposure time to light reflected from the tooth was approximately 11 min without loupes. The weighted blue irradiance values were significantly different for each brand of loupe (Fisher's PLSD p effective blue light hazard was reduced compared to without the loupes. Thus, although using magnification loupes increased the irradiance received at the pupil, the maximum cumulative daily exposure time to reflected light was increased up to 28 min. Further studies are required to determine the ocular hazards of a focused stare when using magnification loupes and the effects of other curing lights used in the dental office.

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

    International Nuclear Information System (INIS)

    Trosic, I.; Pavicic, I.; Jukic, S.

    2008-01-01

    Full text: Halogen curing lights are the most frequently used polymerization source in dental offices. Light-cured bonding systems have become increasingly popular among clinicians because they offer a number of advantages over self-cured adhesives. The effort to increase polymerization quality releases the commercially available high power light density dental curing units. Emitted visible blue light belongs to the range of nonionizing radiation. Common concern in both, patients and dentist grows with regard to the unfavorable effects on the pulp tissue. The aim of study was to evaluate the time and dose dependence effect of halogen light curing unit (Elipar TriLight, ESPE Dental AG, Germany) at the disposed condition modes in vitro. A quartz-tungsten-halogen light source emits radiation of the wavelengths between 400 and 515 nm. This halogen blue light source operates in the three illumination modes, medium (M), exponential (E) and standard (S), and five illumination times. The total irradiance or the light intensity was measured by the light intensity control area on the control panel of device and mean light intensity given by manufacturer was 800 m W/cm 2 . Continuous culture of V79 cells was illuminated in triplicate. The influence of medium mode (M), exponential (E) and standard (S) illumination during 20, 40 and 80 sec on the cell viability, colony forming ability and proliferation of V79 cell culture was investigated. Trypan blue exclusion test was used to determine cell viability, both, in the treated and control cell samples. Colony forming ability was assessed for each exposure time and mode by colony count on post-exposure day 7. Cell proliferation was determined by cell counts for each time and mode of exposure during five post-exposure days. Statistical difference were determined at p<0.05 (Statistica 7.0, StatSoft Inc., USA). Viability of cells was not affected by blue light in view of exposure time and modes. Regardless to exposure or illumination

  10. Degree of conversion and microhardness of TPO-containing resin-based composites cured by polywave and monowave LED units.

    Science.gov (United States)

    Santini, Ario; Miletic, Vesna; Swift, Michael D; Bradley, Mark

    2012-07-01

    To determine the degree of conversion (DC) and Knoop microhardness (KHN) of resin-based composites (RBCs) containing trimethylbenzoyl-diphenylphosphine oxide (TPO) cured by polywave or monowave LED light-curing units (LCUs). Three groups (each n = 5) of Tetric EvoCeram (Ivoclar Vivadent), Vit-l-escence (Ultradent) and Herculite XRV Ultra (Kerr) were prepared in Teflon moulds (5mm in diameter and 2mm thick) and cured with polywave Bluephase(®) G2 (Ivoclar Vivadent), polywave Valo (Ultradent) or monowave Bluephase(®) (Ivoclar Vivadent; control) resulting in 9 groups. DC and KHN were determined using micro-Raman spectroscopy and Knoop microhardness, respectively. High-performance liquid chromatography and nuclear magnetic resonance spectroscopy were used to confirm the presence or absence of TPO in the three uncured materials. Data were statistically analysed using two-way and one-way ANOVA and DC and KHN were correlated using Pearson's correlation (α = 0.05). TPO was confirmed in Tetric EvoCeram and Vit-l-escence but not in Herculite XRV Ultra. All three LCUs produced comparable KHN for Tetric EvoCeram and Herculite XRV Ultra (p > 0.05). Both polywave LCUs resulted in significantly higher KHN for Vit-l-escence and higher DC in Tetric EvoCeram and Vit-l-escence than the monowave Bluephase(®) (p TPO-containing RBCs, but not in Herculite XRV Ultra. DC and KHN were linearly correlated in all three RBCs. Vit-l-escence showed the highest DC and KHN of the three materials tested. The use of polywave LEDs significantly improves both the DC and KHN of materials which contain TPO. This should be taken into account when curing bleached shades of RBCs even if the manufacturers do not indicate the presence of TPO in their materials. Copyright © 2012 Elsevier Ltd. All rights reserved.

  11. Glass transition and degree of conversion of a light-cured orthodontic composite

    Directory of Open Access Journals (Sweden)

    Michela M. D. S. Sostena

    2009-12-01

    Full Text Available OBJECTIVE: This study evaluated the glass transition temperature (Tg and degree of conversion (DC of a light-cured (Fill Magic versus a chemically cured (Concise orthodontic composite. MATERIAL AND METHODS: Anelastic relaxation spectroscopy was used for the first time to determine the Tg of a dental composite, while the DC was evaluated by infrared spectroscopy. The light-cured composite specimens were irradiated with a commercial LED light-curing unit using different exposure times (40, 90 and 120 s. RESULTS: Fill Magic presented lower Tg than Concise (35-84ºC versus 135ºC, but reached a higher DC. CONCLUSIONS: The results of this study suggest that Fill Magic has lower Tg than Concise due to its higher organic phase content, and that when this light-cured composite is used to bond orthodontic brackets, a minimum energy density of 7.8 J/cm² is necessary to reach adequate conversion level and obtain satisfactory adhesion.

  12. Influence of pre-heat treatment and different light-curing units on Vickers hardness of a microhybrid composite resin

    Science.gov (United States)

    Saade, E. G.; Bandeca, M. C.; Rastelli, A. N. S.; Bagnato, V. S.; Porto-Neto, S. T.

    2009-06-01

    The aim of this study was to evaluate the hardness of a dental composite resin submitted to temperature changes before photo-activation with two light-curing unite (LCUs). Five samples (4 mm in diameter and 2 mm in thickness) for each group were made with pre-cure temperatures of 37, 54, and 60°C. The samples were photo-activated with a conventional quartz-tungsten-halogen (QTH) and blue LED LCUs during 40 s. The hardness Vickers test (VHN) was performed on the top and bottom surfaces of the samples. According to the interaction between light-curing unit and different pre-heating temperatures of composite resin, only the light-curing unit provided influences on the mean values of initial Vickers hardness. The light-curing unit based on blue LED showed hardness mean values more homogeneous between the top and bottom surfaces. The hardness mean values were not statistically significant difference for the pre-cure temperature used. According to these results, the pre-heating of the composite resin provide no influence on Vickers hardness mean values, however the blue LED showed a cure more homogeneous than QTH LCU.

  13. Effect of light curing sources on microhardness of different composite resins

    Science.gov (United States)

    Valentino, T. A.; Calabrez-Filho, S.; de Menezes, F. C. H.; Cavalcante, L. M. A.; Pimenta, L. A. F.; de Andrade, M. F.; Dantas, A. A. R.; Rastelli, A. N. S.

    2011-06-01

    This study evaluated the influence of light-curing units (LCUs) on Knoop microhardness (KHN) of different composite resins formulations. Four LCUs, one Quartz-Tungsten-Halogen (QTH) for 20 s, one Argon-Ion-Laser (AL) for 10 s, one Plasma-Arc-Curing (PAC) for 9 s, and one Light-Emitting-Diode (LED) for 20 s, and three composite resins, nanofill and easy cure (Filtek™ Supreme), microhybrid and medium cure (Herculite XRV), and microfill and difficult cure (Heliomolar) were used. Discs (4 × 2 mm2) of each composite resin were divided in 12 Groups and KHN was measured at the top (T) and bottom (B) surfaces. Data were analyzed using two-way ANOVA and Tukey's test ( p < 0.05). Top presented significantly higher KHN than bottom surface for all composite resins and LCUs tested. Statistical significant differences were observed among the LCUs. At the bottom surface QTH and LED presented higher KHN than PAC and LA. However, at the top surface PAC and LA presented similar results than QTH for nanofill and microhybrid composite resins. Different LCUs play an important effect on Knoop microhardness and the composite resin formulations were significant factor on the photosensitivity.

  14. Transport of Light Through White-LED Phosphor Plates

    NARCIS (Netherlands)

    Meretska, Maryna; Thyrrestrup Nielsen, Henri; Lagendijk, Aart; Tukker, Teus; Mosk, Allard; IJzerman, Wilbert; Vos, Willem L.; Di Bartolo, Baldassare; Collins, John; Silvestri, Luciano

    2017-01-01

    Energy efficient generation of white light has become an important societal issue in recent years. The technology of white-light emitting diodes (LEDs) is one of the main directions (Akasaki I, Amano H, Nakamura S, Blue LEDs – filling the world with new light, http://www.nobelprize.org/, 2014;

  15. Transport of light through white-LED phosphor plates

    NARCIS (Netherlands)

    Meretska, Maryna; Thyrrestrup, H.; Lagendijk, Ad; Tukker, T. W.; Mosk, A. P.; IJzerman, W. L.; Vos, Willem L.

    2017-01-01

    Energy efficient generation of white light has become an important societal issue in recent years. The technology of white-light emitting diodes (LEDs) is one of the main directions (Akasaki I, Amano H, Nakamura S, Blue LEDs – filling the world with new light, http://www.nobelprize.org/, 2014;

  16. LED roadway lighting, volume 2 : field evaluations and software comparisons.

    Science.gov (United States)

    2012-10-01

    The use of light-emitting diodes (LEDs) for roadway lighting can potentially save energy costs and reduce the frequency of maintenance. The objective of this study is to explore the current state of the art in LED roadway lighting technology. Three s...

  17. Biaxial Flexural Strength of High-Viscosity Glass-Ionomer Cements Heat-Cured with an LED Lamp during Setting

    Directory of Open Access Journals (Sweden)

    Gustavo Fabián Molina

    2013-01-01

    Full Text Available Adding heat to glass ionomers during setting might improve mechanical properties. The aim was to compare the biaxial flexural strength (BFS between and within four glass ionomers, by time of exposure to a high-intensity LED light-curing unit. Materials and methods. Samples of Fuji 9 Gold Label, Ketac Molar Easymix, ChemFil Rock, and the EQUIA system were divided into three treatment groups (n=30: without heating (Group 1, heated with LED lamp of 1400 mW/cm2 for 30 s while setting (Group 2, and heated with LED lamp of 1400 mW/cm2 for 60 s while setting (Group 3. Samples were stored for 48 hours in distilled water at 37°C until tested. BFS was tested, using a universal testing machine at a crosshead speed of 1 mm/min. Data were analyzed, using ANOVA test with the Bonferroni correction (α=0.05. Heating the glass-ionomer cements with an LED curing light of 1400 mW/cm2 during setting for 30 s increased the BFS value of all GICs. No statistically significant difference in mean BFS scores was found between the EQUIA system and ChemFil Rock at 30 s and 60 s. The mean BFS value was statistically significantly higher for the EQUIA system and ChemFil Rock than for Fuji 9 Gold Label and Ketac Molar Easymix at all exposure times.

  18. Comparison of temperature rise in the pulp chamber with different light curing units: An in-vitro study

    OpenAIRE

    Rajesh Ebenezar A; Anilkumar R; Indira R; Ramachandran S; Srinivasan M

    2010-01-01

    Aims/Objectives : This in vitro study was designed to measure and compare the temperature rise in the pulp chamber with different light curing units. Materials and Methods : The study was done in two settings-in-vitro and in-vivo simulation. In in-vitro setting, 3mm and 6mm acrylic spacers with 4mm tip diameter thermocouple was used and six groups were formed according to the light curing source- 3 Quartz-Tungsten-Halogen (QTH) units and 3 Light-Emitting-Diode (LED) units. For the LED units...

  19. Comparison of temperature rise in the pulp chamber with different light curing units: An in-vitro study

    OpenAIRE

    Rajesh Ebenezar, A V; Anilkumar, R; Indira, R; Ramachandran, S; Srinivasan, M R

    2010-01-01

    Aims/Objectives: This in vitro study was designed to measure and compare the temperature rise in the pulp chamber with different light curing units. Materials and Methods: The study was done in two settings-in-vitro and in-vivo simulation. In in-vitro setting, 3mm and 6mm acrylic spacers with 4mm tip diameter thermocouple was used and six groups were formed according to the light curing source- 3 Quartz-Tungsten-Halogen (QTH) units and 3 Light-Emitting-Diode (LED) units. For the LED units, th...

  20. POWERED LED LIGHTING SUPPLIED FROM PV CELLS

    Directory of Open Access Journals (Sweden)

    Tirshu M.

    2011-12-01

    Full Text Available The paper deals with practical realization of efficient lighting system based on LED’s of 80W total power mounted on corridor ceiling total length of which is 120m and substitutes existing traditional lighting system consisting of 29 lighting blocks with 4 fluorescent lamps each of them and summary power 2088W. Realized lighting system is supplied from two photovoltaic panels of power 170W. Generated energy by PV cells is accumulated in two accumulators of 75Ah capacity and from battery by means of specialized convertor is applied to lighting system. Additionally, paper present data measured by digital weather station (solar radiation and UV index, which is mounted near of PV cells and comparative analyze of solar energy with real energy generated by PV cells is done. Measured parameters by digital weather station are stored by computer in on-line mode.

  1. Effect of LED-LCU light irradiance distribution on mechanical properties of resin based materials

    Energy Technology Data Exchange (ETDEWEB)

    Magalhães Filho, T.R.; Weig, K.M. [Faculdade de Odontologia, Universidade Federal Fluminense, Rua São Paulo 28, CEP 24020-150 Niterói (Brazil); Engenharia Metalúrgica e de Materiais (COPPE), Universidade Federal do Rio de Janeiro, CP 68505, CEP: 21941-972 Rio de Janeiro (Brazil); Costa, M.F. [Engenharia Metalúrgica e de Materiais (COPPE), Universidade Federal do Rio de Janeiro, CP 68505, CEP: 21941-972 Rio de Janeiro (Brazil); Werneck, M.M. [Engenharia Elétrica (COPPE), Universidade Federal do Rio de Janeiro, CP 68504, CEP: 21941-972 Rio de Janeiro (Brazil); Barthem, R.B. [Instituto de Física, Universidade Federal do Rio de Janeiro, CP 68528, CEP: 21941-972 Rio de Janeiro (Brazil); Costa Neto, C.A., E-mail: celio@metalmat.ufrj.br [Engenharia Metalúrgica e de Materiais (COPPE), Universidade Federal do Rio de Janeiro, CP 68505, CEP: 21941-972 Rio de Janeiro (Brazil)

    2016-06-01

    The objective of this study is to analyze the light power distribution along the tip end of the light guide of three LED-LCUs (Light Curing Units) and to evaluate its effect on the mechanical properties of a polymer based dental composite. Firstly, the light power distribution over the whole area of LED-LCU light guide surface was analyzed by three methods: visual projection observation, spectral measurement and optical spectral analysis (OSA). The light power distribution and the total irradiance were different for the three LEDs used, but the wavelength was within the camphorquinone absorption spectrum. The use of a blank sheet was quite on hand to make a qualitative analysis of a beam, and it is costless. Secondly, specimens of a hybrid composite with approximately 8 mm diameter and 2 mm thickness were produced and polymerized by 20 s exposition time to each LED-LCU. Thirdly, the elastic modulus (E) and hardness (HV) were measured throughout the irradiated area by instrumented micro-indentation test (IIT), allowing to correlate localized power and mechanical properties. Both E and HV showed to be very sensitive to local power and wavelength dependent, but they followed the beam power profile. It was also shown that the mechanical properties could be directly correlated to the curing process. Very steep differences in mechanical properties over very short distances may impair the material performance, since residual stresses can easily be built over it. - Highlights: • A resin based composite (RBC) was polymerized by three different Light Emitting Diodes. • Each LED had its beam profile visually, wavelength and power analyzed. • The effective polymerization power (EPP) varied from 28% to 52% of the total beam power. • Wavelength seems to be as relevant as power in the light curing process. • Mechanical properties depend on the simultaneous effect of wavelength and power.

  2. Future Solid State Lighting using LEDs and Diode Lasers

    DEFF Research Database (Denmark)

    Petersen, Paul Michael

    2014-01-01

    significant savings. Solid state lighting (SSL) based on LEDs is today the most efficient light source for generation of high quality white light. Diode lasers, however, have the potential of being more efficient than LEDs for the generation of white light. A major advantage using diode lasers for solid state......Lighting accounts for 20% of all electrical energy usage. Household lighting and commercial lighting such as public and street lighting are responsible for significant greenhouse gas emissions. Therefore, currently many research initiatives focus on the development of new light sources which shows...... lighting is that the high efficiency can be obtained at high light lumen levels in a single element emitter and thus less light sources are required to achieve a desired light level. Furthermore, the high directionality of the generated light from laser diodes increases the energy savings in many...

  3. Knoop hardness of ten resin composites irradiated with high-power LED and quartz-tungsten-halogen lights.

    Science.gov (United States)

    Price, Richard B T; Felix, Corey A; Andreou, Pantelis

    2005-05-01

    This study compared a high-power light-emitting-diode (LED) curing light (FreeLight 2, 3M ESPE) with a quartz-tungsten-halogen (QTH) light (TriLight, 3M ESPE) to determine which was the better at photo-polymerising 10 resin composites. Class I preparations were prepared 4-mm deep into human teeth and filled with 10 different composites. The composites were irradiated for 50% or 100% of their recommended times using the LED light, and for 100% of their recommended times with the QTH light on either the high or medium power setting. Fifteen minutes later, the Knoop hardness of the composites was measured to a depth of 3.5 mm from the surface. When irradiated by the LED light for their recommended curing times, the Knoop hardness of all 10 composites stayed above 80% of the maximum hardness of the composite to a depth of at least 1.5 mm; three composites maintained a Knoop hardness that was more than 80% of their maximum hardness to a depth of 3.5 mm. Repeated measurements analysis of variance indicated that all the two-way and three-way interactions between the curing light, depth, and composite were significant (p hardness values. The LED light, used for the composite manufacturer's recommended time, was ranked the best at curing the composites to a depth of 3mm (p power setting.

  4. Influence of light curing and sample thickness on microhardness of a composite resin

    Directory of Open Access Journals (Sweden)

    Flávio HB Aguiar

    2009-05-01

    Full Text Available Flávio HB Aguiar1, Kelly RM Andrade1, Débora AN Leite Lima1, Gláucia MB Ambrosano2, José R Lovadino11Department of Restorative Dentistry; 2Department of Social Dentistry/Statistics, Piracicaba Dental School, State University of Campinas, SP, BrazilAbstract: The aim of this in vitro study was to evaluate the influence of light-curing units and different sample thicknesses on the microhardness of a composite resin. Composite resin specimens were randomly prepared and assigned to nine experimental groups (n = 5: considering three light-curing units (conventional quartz tungsten halogen [QTH]: 550 mW/cm2 – 20 s; high irradiance QTH: 1160 mW/cm2 – 10 s; and light-emitting diode [LED]: 360 mW/cm2 – 40 s and three sample thicknesses (0.5 mm, 1 mm, and 2 mm. All samples were polymerized with the light tip 8 mm away from the specimen. Knoop microhardness was then measured on the top and bottom surfaces of each sample. The top surfaces, with some exceptions, were almost similar; however, in relation to the bottom surfaces, statistical differences were found between curing units and thicknesses. In all experimental groups, the 0.5-mm-thick increments showed microhardness values statistically higher than those observed for 1- and -2-mm increments. The conventional and LED units showed higher hardness mean values and were statistically different from the high irradiance unit. In all experimental groups, microhardness mean values obtained for the top surface were higher than those observed for the bottom surface. In conclusion, higher levels of irradiance or thinner increments would help improve hybrid composite resin polymerization.Keywords: photo-polymerization, light-curing distance, light-curing units, composite resin, composite thickness, microhardness

  5. Exterior LED Lighting Projects at Princeton University

    Energy Technology Data Exchange (ETDEWEB)

    Davis, Robert G. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Evans, William [Princeton Univ., NJ (United States); Murphy, Arthur T. [Princeton Univ., NJ (United States); Perrin, Tess E. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2015-10-01

    For this report, PNNL / the U.S. Department of Energy (DOE) studied a series of past exterior lighting projects at Princeton, in order to document Princeton’s experiences with solid-state lighting (SSL) and the lessons learned along the way, and to show how their approach to SSL projects evolved as their own learning expanded and as the products available improved in performance and sophistication.

  6. Effect of LED-LCU light irradiance distribution on mechanical properties of resin based materials.

    Science.gov (United States)

    Magalhães Filho, T R; Weig, K M; Costa, M F; Werneck, M M; Barthem, R B; Costa Neto, C A

    2016-06-01

    The objective of this study is to analyze the light power distribution along the tip end of the light guide of three LED-LCUs (Light Curing Units) and to evaluate its effect on the mechanical properties of a polymer based dental composite. Firstly, the light power distribution over the whole area of LED-LCU light guide surface was analyzed by three methods: visual projection observation, spectral measurement and optical spectral analysis (OSA). The light power distribution and the total irradiance were different for the three LEDs used, but the wavelength was within the camphorquinone absorption spectrum. The use of a blank sheet was quite on hand to make a qualitative analysis of a beam, and it is costless. Secondly, specimens of a hybrid composite with approximately 8mm diameter and 2mm thickness were produced and polymerized by 20s exposition time to each LED-LCU. Thirdly, the elastic modulus (E) and hardness (HV) were measured throughout the irradiated area by instrumented micro-indentation test (IIT), allowing to correlate localized power and mechanical properties. Both E and HV showed to be very sensitive to local power and wavelength dependent, but they followed the beam power profile. It was also shown that the mechanical properties could be directly correlated to the curing process. Very steep differences in mechanical properties over very short distances may impair the material performance, since residual stresses can easily be built over it. Copyright © 2016 Elsevier B.V. All rights reserved.

  7. A Comparison of the Shear Bond Strength of Orthodontic Brackets Bonded With Light-Emitting Diode and Halogen Light-Curing Units

    Directory of Open Access Journals (Sweden)

    SM. Abtahi

    2006-09-01

    Full Text Available Statement of the problem: Various methods such as light emitting diode (LED have been used to enhance the polymerization of resin-based orthodontic adhesives. There is a lack of information on the advantages and disadvantages of different light curing systems.Purpose: The aim of this study was to compare the effect of LED and halogen light curing systems on the shear bond strength of orthodontic brackets.Materials and Methods: Forty extracted human premolars were etched with 37% phosphoric acid and cleansed with water spray and air dried. The sealant was applied on the tooth surface and the brackets were bonded using Transbond adhesive (3M Unitek,Monrovia, Calif. Adhesives were cured for 40 and 20 seconds with halogen (Blue Light, APOZA, Taiwan and LED (Blue dent, Smart, Yugoslavia light-curing systems,respectively. Specimens were thermocycled 2500 times (from 5 to 55 °C and the shear bond strength of the adhesive system was evaluated with an Universal testing machine (Zwick GmbH, Ulm, Germany at a crosshead speed of 1 mm/min until the bracketswere detached from the tooth. Adhesive remnant index (ARI scores were determined after bracket failure. The data were submitted to statistical analysis, using Mann-Whitney analysis and t-test.Results: No significant difference was found in bond strength between the LED and halogen groups (P=0.12. A significant difference was not observed in the adhesive remnant index scores between the two groups (P=0.97.Conclusion: Within the limitations of this in vitro study, the shear bond strength of resin-based orthodontic adhesives cured with a LED was statistically equivalent to those cured with a conventional halogen-based unit. LED light-curing units can be suggested for the polymerization of orthodontic bonding adhesives.

  8. LED light requirements ... for greenhouses and growth rooms

    NARCIS (Netherlands)

    Nederhoff, E.M.

    2011-01-01

    LEDs have potential for use as grow lights in greenhouses to supplement low natural light levels, and also for use in growth rooms and 'plant factories' as the main light source. The light spectrum is critical. Unfortunately, it seems that there is not a simple recipe freely available for growing

  9. Standardization of distance and angulation of light curing unit tip using distometer

    OpenAIRE

    Radzi, Z.; Abu Kasim, N.H.; Yahya, N. A.; Abu Osman, N.A.; Kassim, N.L.

    2017-01-01

    The purpose of this study was to investigate the light intensity of selected light curing unit with varying distance and angulation of the light curing tip and lightmeter. Four types of light units; Spectrum 800 (Dentsply), Coltulux 3 (Coltene), Elipar FreeLight 2 (3M Espe) and Starlight Pro (Mectron) were evaluated for light intensity at various distance between the light curing tip and the lightometer Cure Rite Denstply (0, 1, 3, 5, 10 and 15 mm). The light curing units were angulated ...

  10. LED light engine concept with ultra-high scalable luminance

    Science.gov (United States)

    Hoelen, Christoph; de Boer, Dick; Bruls, Dominique; van der Eyden, Joost; Koole, Rolf; Li, Yun; Mirsadeghi, Mo; Vanbroekhoven, Vincent; Van den Bergh, John-John; Van de Voorde, Patrick

    2016-03-01

    Although LEDs have been introduced successfully in many general lighting applications during the past decade, high brightness light source applications are still suffering from the limited luminance of LEDs. High power LEDs are generally limited in luminance to ca 100 Mnit (108 lm/m2sr) or less, while dedicated devices for projection may achieve luminance values up to ca 300 Mnit with phosphor converted green. In particular for high luminous flux applications with limited étendue, like in front projection systems, only very modest luminous flux values in the beam can be achieved with LEDs compared to systems based on discharge lamps. In this paper we introduce a light engine concept based on a light converter rod pumped with blue LEDs that breaks through the étendue and brightness limits of LEDs, enabling LED light source luminance values that are more than 4 times higher than what can be achieved with LEDs so far. In LED front projection systems, green LEDs are the main limiting factor. With our green light emitting modules, peak luminance values well above 1.2 Gnit have been achieved, enabling doubling of the screen brightness of LED based DLP projection systems, and even more when this technology is applied to other colors as well. This light source concept, introduced as the ColorSpark High Lumen Density (HLD) LED technology, enables a breakthrough in the performance of LED-based light engines not only for projection, where >2700 ANSI lm was demonstrated, but for a wide variety of high brightness applications.

  11. Effect of preheating and light-curing unit on physicochemical properties of a bulk fill composite.

    Science.gov (United States)

    Theobaldo, Jéssica Dias; Aguiar, Flávio Henrique Baggio; Pini, Núbia Inocencya Pavesi; Lima, Débora Alves Nunes Leite; Liporoni, Priscila Christiane Suzy; Catelan, Anderson

    2017-01-01

    The aim of this study is to evaluate the effect of composite preheating and polymerization mode on degree of conversion (DC), microhardness (KHN), plasticization (P), and depth of polymerization (DP) of a bulk fill composite. Forty disc-shaped samples (n = 5) of a bulk fill composite were prepared (5 × 4 mm thick) and randomly divided into 4 groups according to light-curing unit (quartz-tungsten-halogen [QTH] or light-emitting diode [LED]) and preheating temperature (23 or 54 °C). A control group was prepared with a flowable composite at room temperature. DC was determined using a Fourier transform infrared spectrometer, KHN was measured with a Knoop indenter, P was evaluated by percentage reduction of hardness after 24 h of ethanol storage, and DP was obtained by bottom/top ratio. Data were statistically analyzed by analysis of variance and Tukey's test (α = 0.05). Regardless of light-curing, the highest preheating temperature increased DC compared to room temperature on bottom surface. LED showed a higher DC compared to QTH. Overall, DC was higher on top surface than bottom. KHN, P, and DP were not affected by curing mode and temperature, and flowable composite showed similar KHN, and lower DC and P, compared to bulk fill. Composite preheating increased the polymerization degree of 4-mm-increment bulk fill, but it led to a higher plasticization compared to the conventional flowable composite evaluated.

  12. Final report LED solutions for public lighting; Eindrapportage LED oplossingen voor openbare verlichting

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2010-04-15

    This report examines if and how LED can be used for public lighting on a large scale. Pilot projects in 29 municipalities were assessed to test the usefulness of LED lighting. This final report provides answers to the questions that relate to the feasibility of the deployment of LED in public lighting and provides some practical pointers. [Dutch] Er is onderzocht of, en zo ja op welke wijze, LED grootschalig toegepast kan worden in de openbare verlichting (OVL). In 29 gemeenten in Nederland zijn proefprojecten geevalueerd om LED verlichting te toetsen op bruikbaarheid. Deze eindrapportage geeft antwoord op vragen die betrekking hebben op de haalbaarheid van de toepassing van LED binnen de OVL en geeft wat praktische aandachtspunten.

  13. Warm white LEDs lighting over Ra=95 and its applications

    Science.gov (United States)

    Kobashi, Katsuya; Taguchi, Tsunemasa

    2007-02-01

    We have for the first time developed warm white LEDs lighting using a combination of near ultraviolet LED and three-band (red, green and blue) white phosphors. This LED has the average color-rendering index Ra=96. Moreover, special color-rendering index R9 (red) and R15 (face color of Japanese) are estimated to be 95 and 97, respectively. We will describe the results of evaluation on the medical lighting applications such as operation, treatment and endoscope experiments, application to the LED fashions and application to the Japanese antique art (ink painting) lighting.

  14. Effect of light-curing method and indirect veneering materials on the Knoop hardness of a resin cement

    Directory of Open Access Journals (Sweden)

    Nelson Tetsu Iriyama

    2009-06-01

    Full Text Available This study evaluated the Knoop hardness of a dual-cured resin cement (Rely-X ARC activated solely by chemical reaction (control group or by chemical / physical mode, light-cured through a 1.5 mm thick ceramic (HeraCeram or composite (Artglass disc. Light curing was carried out using conventional halogen light (XL2500 for 40 s (QTH; light emitting diodes (Ultrablue Is for 40 s (LED; and Xenon plasma arc (Apollo 95E for 3 s (PAC. Bovine incisors had their buccal face flattened and hybridized. On this surface a rubber mold (5 mm in diameter and 1 mm in height was bulk filled with the resin cement. A polyester strip was seated for direct light curing or through the discs of veneering materials. After dry storage in the dark (24 h 37°C, the samples (n = 5 were sectioned for hardness (KHN measurements, taken in a microhardness tester (50 gF load 15 s. The data were statistically analyzed by ANOVA and Tukey's test (α = 0.05. The cement presented higher Knoop hardness values with Artglass for QTH and LED, compared to HeraCeram. The control group and the PAC/Artglass group showed lower hardness values compared to the groups light-cured with QTH and LED. PAC/HeraCeram resulted in the worst combination for cement hardness values.

  15. Comparative life cycle assessment of LED lighting products

    OpenAIRE

    Casamayor, JL; Su, D; Ren, Z

    2017-01-01

    LED lighting products used in lighting applications and their subsequent environmental impact are growing rapidly. However, there are no in-depth updated studies that show how to assess and compare them for eco-design purposes. This research aims to add insights in this area to inform eco-design by assessing and comparing the environmental impact of a new LED eco-lighting product with an existing LED lighting product. A cradle to grave Life Cycle assessment (LCA) was conducted using ReCiPe Mi...

  16. High Output LED-Based Profile Lighting Fixture

    DEFF Research Database (Denmark)

    Török, Lajos; Beczkowski, Szymon; Munk-Nielsen, Stig

    2011-01-01

    Recent developments in power light emitting diode (LED) industry have made LEDs suitable for being efficiently used in high intensity lighting fixtures instead of the commonly used high intensity discharge (HID) lamps. A high output LEDbased profile-light fixture is presented in this paper...... the grid and delivers the required voltage to the LEDdriver which is a dual interleaved buck converter. Twelve highpower CBT-90 LEDs have been connected in a 4xRGBconfiguration to deliver high output of saturated colors without the need for subtractive color filters. More than 6000 lm of fixture light...

  17. Effect of different light-curing devices and aging procedures on composite knoop microhardness.

    Science.gov (United States)

    Voltarelli, Fernanda Regina; dos Santos-Daroz, Claudia Batitucci; Alves, Marcelo Corrêa; Peris, Alessandra Rezende; Marchi, Giselle Maria

    2009-01-01

    The aim of this study was to evaluate the effect of light-curing devices (Halogen/HAL, Light Emitting Diodes/LED, Argon Laser/LAS and Plasma Arc/PAC) and aging procedures (Mechanical Cycling/MC, Thermal Cycling/TC, Storage/S, MC+TC and MC+TC+S) on the micro-hardness of bottom/B and top/T surfaces of 2-mm-high composite resin cylinders. The Knoop microhardness test (25 g, 20 s) on both B and T was performed before and after each aging procedure. For B and T, before aging procedures, PAC showed reduced polymerization effectiveness when compared with HAL. In the T, after TC, PAC and LAS had also showed reduced polymerization effectiveness when compared to HAL and LED. For all light-curing devices, MC+TC+S and S affected the Knoop microhardness values. In the B, no difference could be observed among the aging procedures for PAC. From all light-curing units, PAC may have rendered composites of reduced quality and the storage aging procedures were the most harmful to the polymer hardness.

  18. Effect of different light-curing devices and aging procedures on composite knoop microhardness

    Directory of Open Access Journals (Sweden)

    Fernanda Regina Voltarelli

    2009-12-01

    Full Text Available The aim of this study was to evaluate the effect of light-curing devices (Halogen/HAL, Light Emitting Diodes/LED, Argon Laser/LAS and Plasma Arc/PAC and aging procedures (Mechanical Cycling/MC, Thermal Cycling/TC, Storage/S, MC+TC and MC+TC+S on the micro-hardness of bottom/B and top/T surfaces of 2-mm-high composite resin cylinders. The Knoop microhardness test (25 g, 20 s on both B and T was performed before and after each aging procedure. For B and T, before aging procedures, PAC showed reduced polymerization effectiveness when compared with HAL. In the T, after TC, PAC and LAS had also showed reduced polymerization effectiveness when compared to HAL and LED. For all light-curing devices, MC+TC+S and S affected the Knoop microhardness values. In the B, no difference could be observed among the aging procedures for PAC. From all light-curing units, PAC may have rendered composites of reduced quality and the storage aging procedures were the most harmful to the polymer hardness.

  19. LED and Halogen Light Transmission through a CAD/CAM Lithium Disilicate Glass-Ceramic.

    Science.gov (United States)

    Pereira, Carolina Nemesio de Barros; De Magalhães, Cláudia Silami; Daleprane, Bruno; Peixoto, Rogéli Tibúrcio Ribeiro da Cunha; Ferreira, Raquel da Conceição; Cury, Luiz Alberto; Moreira, Allyson Nogueira

    2015-01-01

    The effect of thickness, shade and translucency of CAD/CAM lithium disilicate glass-ceramic on light transmission of light-emitting diode (LED) and quartz-tungsten-halogen units (QTH) were evaluated. Ceramic IPS e.max CAD shades A1, A2, A3, A3.5, high (HT) and low (LT) translucency were cut (1, 2, 3, 4 and 5 mm). Light sources emission spectra were determined. Light intensity incident and transmitted through each ceramic sample was measured to determine light transmission percentage (TP). Statistical analysis used a linear regression model. There was significant interaction between light source and ceramic translucency (p=0.008) and strong negative correlation (R=-0.845, pceramic thickness and TP. Increasing one unit in thickness led to 3.17 reduction in TP. There was no significant difference in TP (p=0.124) between shades A1 (ß1=0) and A2 (ß1=-0.45) but significant reduction occurred for A3 (ß1=-0.83) and A3.5 (ß1=-2.18). The interaction QTH/HT provided higher TP (ß1=0) than LED/HT (ß1=-2.92), QTH/LT (ß1=-3.75) and LED/LT (ß1=-5.58). Light transmission was more effective using halogen source and high-translucency ceramics, decreased as the ceramic thickness increased and was higher for the lighter shades, A1 and A2. From the regression model (R2=0.85), an equation was obtained to estimate TP value using each variable ß1 found. A maximum TP of 25% for QTH and 20% for LED was found, suggesting that ceramic light attenuation could compromise light cured and dual cure resin cements polymerization.

  20. LED lighting combined with solar panels in developing countries

    OpenAIRE

    Amogpai, Ater

    2011-01-01

    The aim of the work was to find out the functionality of LED lighting combined with solar panels in developing countries and to find out the availability of solar energy in different geographical locations. Another aim of the work was to understand the advantages and disadvantages of photovoltaic systems and the optimum combination of PV systems for lighting. Measurements of photovoltaic systems combined with LEDs and fluorescent lighting were conducted in an office building in Finland. ...

  1. Temperature Rise Induced by Light Curing Unit Can Shorten Enamel Acid-Etching Time

    Directory of Open Access Journals (Sweden)

    Ahmad Najafi Abrandabadi

    2016-08-01

    Full Text Available Objectives: The aim of this in-vitro study was to assess the thermal effect of light emitting diode (LED light curing unit on the enamel etching time.Materials and Methods: Three treatment groups with 15 enamel specimens each were used in this study: G1: Fifteen seconds of etching, G2: Five seconds of etching, G3: Five seconds of etching plus LED light irradiation (simultaneously. The micro shear bond strength (µSBS of composite resin to enamel was measured.Results: The mean µSBS values ± standard deviation were 51.28±2.35, 40.47±2.75 and 50.00±2.59 MPa in groups 1, 2 and 3, respectively. There was a significant difference between groups 1 and 2 (P=0.013 and between groups 2 and 3 (P=0.032 in this respect, while there was no difference between groups 1 and 3 (P=0.932.Conclusion: Simultaneous application of phosphoric acid gel over enamel surface and light irradiation using a LED light curing unit decreased enamel etching time to five seconds without compromising the µSBS.

  2. Temperature Rise Induced by Light Curing Unit Can Shorten Enamel Acid-Etching Time.

    Science.gov (United States)

    Najafi Abrandabadi, Ahmad; Sheikh-Al-Eslamian, Seyedeh Mahsa; Panahandeh, Narges

    2015-12-01

    The aim of this in-vitro study was to assess the thermal effect of light emitting diode (LED) light curing unit on the enamel etching time. Three treatment groups with 15 enamel specimens each were used in this study: G1: Fifteen seconds of etching, G2: Five seconds of etching, G3: Five seconds of etching plus LED light irradiation (simultaneously). The micro shear bond strength (μSBS) of composite resin to enamel was measured. The mean μSBS values ± standard deviation were 51.28±2.35, 40.47±2.75 and 50.00±2.59 MPa in groups 1, 2 and 3, respectively. There was a significant difference between groups 1 and 2 (P=0.013) and between groups 2 and 3 (P=0.032) in this respect, while there was no difference between groups 1 and 3 (P=0.932). Simultaneous application of phosphoric acid gel over enamel surface and light irradiation using a LED light curing unit decreased enamel etching time to five seconds without compromising the μSBS.

  3. Intelligent control of dynamic LED lighting; Intelligent styring af dynamisk LED belysning. Slutrapport

    Energy Technology Data Exchange (ETDEWEB)

    Thorseth, A.; Corell, D.; Hansen, Soeren S.; Dam-Hansen, C.; Petersen, Paul Michael

    2013-01-15

    The project has resulted in a prototype of a new intelligent lighting control system. The control system enables the end user to control his or her own local lighting environment (lighting zone) according to individual preferences and needs. The report provides a description of how the developed intelligent lighting system is composed and functions. The system is designed as a work lamp that enables dynamic change of the light color scheme according to a number of light control algorithms. It is specifically designed in relation to user tests of the intelligent lighting system, which is carried out in the final part of the project. An intelligent and advanced control of LED lighting was developed, which enables optimization of the user's light conditions in a given situation. Based on a number of known parameters, the system can control lighting so that at any time optimal light conditions are created, using a minimum of electric power. (LN)

  4. Comparison of light transmittance in different thicknesses of zirconia under various light curing units

    OpenAIRE

    Cekic-Nagas, Isil; Egilmez, Ferhan; Ergun, Gulfem

    2012-01-01

    PURPOSE The objective of this study was to compare the light transmittance of zirconia in different thicknesses using various light curing units. MATERIALS AND METHODS A total of 21 disc-shaped zirconia specimens (5 mm in diameter) in different thicknesses (0.3, 0.5 and 0.8 mm) were prepared. The light transmittance of the specimens under three different light-curing units (quartz tungsten halogen, light-emitting diodes and plasma arc) was compared by using a hand-held radiometer. Statistical...

  5. Development of high-performance solar LED lighting system

    KAUST Repository

    Huang, B.J.

    2010-08-01

    The present study developed a high-performance charge/discharge controller for stand-alone solar LED lighting system by incorporating an nMPPO system design, a PWM battery charge control, and a PWM battery discharge control to directly drive the LED. The MPPT controller can then be removed from the stand-alone solar system and the charged capacity of the battery increases 9.7%. For LED driven by PWM current directly from battery, a reliability test for the light decay of LED lamps was performed continuously for 13,200 h. It has shown that the light decay of PWM-driven LED is the same as that of constant-current driven LED. The switching energy loss of the MOSFET in the PWM battery discharge control is less than 1%. Three solar-powered LED lighting systems (18 W, 100 W and 150 W LED) were designed and built. The long-term outdoor field test results have shown that the system performance is satisfactory with the control system developed in the present study. The loss of load probability for the 18 W solar LED system is 14.1% in winter and zero in summer. For the 100 W solar LED system, the loss of load probability is 3.6% in spring. © 2009 Elsevier Ltd. All rights reserved.

  6. Effect of light-activation with different light-curing units and time intervals on resin cement bond strength to intraradicular dentin.

    Science.gov (United States)

    Miguel-Almeida, Maria Eleonora; Azevedo, Mario Lucio da Costa; Rached-Júnior, Fuad Abi; Oliveira, Camila Favero; Silva, Ricardo Gariba; Messias, Danielle Cristine

    2012-01-01

    The aim of this study was to assess the bond strength of a resin cement to intraradicular dentin varying the light-curing unit and the moment at which the light was applied. Post spaces of endodontically treated canines were prepared. The roots were distributed into 6 groups (n=10) according to the light-curing unit and the moment of light exposure: I) Quartz tungsten halogen-600 mW/cm² (QTH) + immediate light activation (t0); II) QTH + light activation after 10 min (t10); III) Light-emitting diodes (LED)-800 mW/cm² (LED-800)+ t0; IV) LED-800 + t10; V) LED-1,500 mW/cm² (LED-1500)+ t0; VI) LED-1500 + t10. After post cementation, slices from coronal, middle and apical post/root regions were submitted to the push-out test and failure evaluation. It was verified that LED-800 (4.40 ± 3.00 MPa) and LED-1500 (4.67 ± 3.04 MPa) provided bond strength statistically superior to QTH (3.13 ± 1.76 MPa) (p0.05). There was no significant difference between t0 and t10 (p>0.05). Coronal post/root region (4.75 ± 3.10 MPa) presented significantly higher bond strength than the apical (3.32 ± 2.30 MPa) (plight-activation, regardless of the moment of light exposure.

  7. Visual color matching system based on RGB LED light source

    Science.gov (United States)

    Sun, Lei; Huang, Qingmei; Feng, Chen; Li, Wei; Wang, Chaofeng

    2018-01-01

    In order to study the property and performance of LED as RGB primary color light sources on color mixture in visual psychophysical experiments, and to find out the difference between LED light source and traditional light source, a visual color matching experiment system based on LED light sources as RGB primary colors has been built. By simulating traditional experiment of metameric color matching in CIE 1931 RGB color system, it can be used for visual color matching experiments to obtain a set of the spectral tristimulus values which we often call color-matching functions (CMFs). This system consists of three parts: a monochromatic light part using blazed grating, a light mixing part where the summation of 3 LED illuminations are to be visually matched with a monochromatic illumination, and a visual observation part. The three narrow band LEDs used have dominant wavelengths of 640 nm (red), 522 nm (green) and 458 nm (blue) respectively and their intensities can be controlled independently. After the calibration of wavelength and luminance of LED sources with a spectrophotometer, a series of visual color matching experiments have been carried out by 5 observers. The results are compared with those from CIE 1931 RGB color system, and have been used to compute an average locus for the spectral colors in the color triangle, with white at the center. It has been shown that the use of LED is feasible and has the advantages of easy control, good stability and low cost.

  8. Lifetime prediction of LED lighting systems considering thermal coupling between LED sources and drivers

    DEFF Research Database (Denmark)

    Alfarog, Azzarn Orner; Qu, Xiaohui; Wang, Huai

    2017-01-01

    The lifetime prediction of LED lighting system is important to guide the designers to fulfill the design specifications and to benchmark the cost-competitiveness of different lighting technologies. Currently, the lifetime of LED system is usually predicted from the source part and the driver part...... separately, and then the thermal design is also optimized independently. In practice, the LED source and driver are usually compacted in a single fixture. The heat dissipated from LED source and driver will be coupled together and affect the heat transfer performance, which may degrade the whole system...... and accelerate the failure. In this paper, a new thermal model concerning the thermal coupling is proposed with Finite Element Method (FEM) simulation for parameter acquirement. The proposed model has a better estimation of the thermal stresses of key components in the LED lamps and therefore an improved...

  9. A comparative evaluation of the shear bond strength of five different orthodontic bonding agents polymerized using halogen and light-emitting diode curing lights: an in vitro investigation.

    Science.gov (United States)

    Banerjee, Sujoy; Banerjee, Rajlakshmi

    2011-01-01

    With the introduction of photosensitive (light-activated) restorative materials in orthodontics, various methods have been suggested to enhance the polymerization of the materials used, including use of more powerful light curing devices. Bond strength is an important property and determines the amount of force delivered and the treatment duration. Many light-cured bonding materials have become popular but it is the need of the hour to determine the bonding agent that is the most efficient and has the desired bond strength. To evaluate and compare the shear bond strengths of five different orthodontic light cure bonding materials cured with traditional halogen light and low-intensity light-emitting diode (LED) light curing unit. 100 human maxillary premolar teeth, extracted for orthodontic purpose, were used to prepare the samples. 100 maxillary stainless steel bicuspid brackets of 0.018 slot of Roth prescription, manufactured by D-tech Company, were bonded to the prepared tooth surfaces of the mounted samples using five different orthodontic bracket bonding light-cured materials, namely, Enlight, Fuji Ortho LC (resin-modified glass ionomer cement), Orthobond LC, Relybond, and Transbond XT. The bond strength was tested on an Instron Universal testing machine (model no. 5582). In Group 1 (halogen group), Enlight showed the highest shear bond strength (16.4 MPa) and Fuji Ortho LC showed the least bond strength (6.59 MPa) (P value 0.000). In Group 2 (LED group), Transbond showed the highest mean shear bond strength (14.6 MPa) and Orthobond LC showed the least mean shear bond strength (6.27 MPa) (P value 0.000). There was no statistically significant difference in the shear bond strength values of all samples cured using either halogen (mean 11.49 MPa) or LED (mean 11.20 MPa), as the P value was 0.713. Polymerization with both halogen and LED resulted in shear bond strength values which were above the clinically acceptable range given by Reynolds. The LED light curing

  10. A comparative evaluation of the shear bond strength of five different orthodontic bonding agents polymerized using halogen and light-emitting diode curing lights: An in vitro investigation

    Directory of Open Access Journals (Sweden)

    Sujoy Banerjee

    2011-01-01

    Full Text Available Purpose: With the introduction of photosensitive (light-activated restorative materials in orthodontics, various methods have been suggested to enhance the polymerization of the materials used, including use of more powerful light curing devices. Bond strength is an important property and determines the amount of force delivered and the treatment duration. Many light-cured bonding materials have become popular but it is the need of the hour to determine the bonding agent that is the most efficient and has the desired bond strength. Aim: To evaluate and compare the shear bond strengths of five different orthodontic light cure bonding materials cured with traditional halogen light and low-intensity light-emitting diode (LED light curing unit. Materials and Methods: 100 human maxillary premolar teeth, extracted for orthodontic purpose, were used to prepare the samples. 100 maxillary stainless steel bicuspid brackets of 0.018 slot of Roth prescription, manufactured by D-tech Company, were bonded to the prepared tooth surfaces of the mounted samples using five different orthodontic bracket bonding light-cured materials, namely, Enlight, Fuji Ortho LC (resin-modified glass ionomer cement, Orthobond LC, Relybond, and Transbond XT. The bond strength was tested on an Instron Universal testing machine (model no. 5582. Results: In Group 1 (halogen group, Enlight showed the highest shear bond strength (16.4 MPa and Fuji Ortho LC showed the least bond strength (6.59 MPa (P value 0.000. In Group 2 (LED group, Transbond showed the highest mean shear bond strength (14.6 MPa and Orthobond LC showed the least mean shear bond strength (6.27 MPa (P value 0.000. There was no statistically significant difference in the shear bond strength values of all samples cured using either halogen (mean 11.49 MPa or LED (mean 11.20 MPa, as the P value was 0.713. Conclusion: Polymerization with both halogen and LED resulted in shear bond strength values which were above the

  11. LED lamps in shipboard lighting systems: Aspects of electromagnetic compatibility

    Directory of Open Access Journals (Sweden)

    Beley V. F.

    2016-12-01

    Full Text Available Trends in the development of different types of light sources and their energy characteristics have been described in the paper. Analysis of regulatory documents has been given. The results of experimental studies of a number of modern LED lamps have been described. Investigation has been made for a number of LED lamps produced by Philips, Xavax and Melitec. The experimental data have been obtained with the complex of devices: the dual-channel oscilloscope (GDS-71042, the power quality analyzer (Fluke-434 and the multi-function device EcoLight-01 (light-, pulse- and luminance meter. It has been shown that operation of LED lamps is characterized by emission of higher current harmonics and reactive power consumption, which depends on the type and design of the lamp driver. It has been found that the value of luminance created by LED lamps in case of acceptable (for ships prolonged deviation of voltage (–10 % is reduced by 3 %; in case of permissible short-term voltage deviation (–20 % luminance is reduced by 7 %. For incandescent lamps this indicator is characterized by a decrease in luminance by 40 % and 60 %, respectively. Despite the low sensitivity to voltage changes (in comparison with other types of lamps, the operation of LED lamps is also associated with the appearance of flicker. Absence of limitations for fluctuations of the light flux in shipboard lighting systems and imperfection of methods for determining the flicker make it difficult to ensure electromagnetic compatibility of LED lamps. Therefore due to reliability, environmental friendliness, energy efficiency and lumen maintenance LED lamps have prospects for introduction into shipboard lighting systems. However, to ensure electromagnetic compatibility of LED lighting systems it is necessary to conduct a detailed study of energy characteristics of LED lamps and to develop appropriate regulatory requirements and technical solutions.

  12. A new LED light source for display cases

    DEFF Research Database (Denmark)

    Dam-Hansen, Carsten; Petersen, Paul Michael

    Abstract: We report a new LED light source suitable for illumination of gold objects. It has a variable correlated color temperature from 2760 K to 2200 K with a high color rendering index up to 97.......Abstract: We report a new LED light source suitable for illumination of gold objects. It has a variable correlated color temperature from 2760 K to 2200 K with a high color rendering index up to 97....

  13. Interior LED Lighting Technology. Navy Energy Technology Validation (Techval) Program

    Science.gov (United States)

    2015-09-01

    evaluated using the Illumination Engineering Societies’ (IES) TM-21 manual. The TM- 21 manual provides a standardized method for evaluating when an LED...the equipment. The Cree luminaires installed in this study are rated for 75,000 hours of service, based on calculation methods that extrapolated...should be replaced with LED lamps. • Replace MR-16 lamps with LED lamps since this type of fixture is used to provide accent lighting and is

  14. [Study on the safety of blue light leak of LED].

    Science.gov (United States)

    Shen, Chong-Yu; Xu, Zheng; Zhao, Su-Ling; Huang, Qing-Yu

    2014-02-01

    In this paper, the blue light properties of LED illumination devices have been investigated. Against the status quo of China's LED lighting, we measured the spectrum component of LED lamps and analyzed the photobiological safety under the current domestic and international standards GB/T 20145-2006/CIE S009/E: 2002 and IEC62471: 2006 standards as well as CTL-0744_2009-laser resolution, which provides the reference to the manufacture of LED lighting lamps as well as related safety standards and laws. If the radiance intensity of blue light in LED is lower than 100 W x m(-2) x Sr(-1), there is no harm to human eyes. LEDs will not cause harm to human eyes under normal use, but we should pay attention to the protection of special populations (children), and make sure that they avoid looking at a light source for a long time. The research has found that the blue-rich lamps can affect the human rule of work and rest, and therefore, the LED lamps with color temperature below 4 000 K and color rendering index of 80 are suitable for indoor use. At the same time, the lamps with different parameters should be selected according to the different distances.

  15. The applicability of DPSS laser for light curing of composite resins.

    Science.gov (United States)

    Kwon, Yong Hoon; Jang, Chang-Min; Shin, Dong-Hee; Seol, Hyo-Joung; Kim, Hyung-Il

    2008-10-01

    The applicability of diode-pumped solid state (DPSS) laser for light curing the composite resins was tested with a quartz-tungsten-halogen lamp-based unit and a light emitting diode unit. The emission spectra of the light-curing systems used match with the absorption spectrum of camphorquinone. Among the light-curing systems, DPSS laser showed the narrowest emission bandwidth. The light intensity of DPSS laser was approximately 64% of the other two light-curing units. In most specimens, DPSS laser showed the least attenuation of the number of incident photons. On the top surface, specimens cured with DPSS laser showed similar microhardness values compared to the specimens cured with the other two light-curing units. During the light curing, DPSS laser induced the lowest temperature rise (25.5-35.5 degrees C) in the specimens compared to the other two light-curing units (34.2-41.7 degrees C). In conclusion, DPSS laser has high potential to be an alternative to the other light-curing units or a new light-curing unit.

  16. Temperature rise during adhesive and composite polymerization with different light-curing sources.

    Science.gov (United States)

    Pereira Da Silva, A; Alves Da Cunha, L; Pagani, C; De Mello Rode, S

    2010-05-01

    This study evaluated the temperature rise of the adhesive system Single Bond (SB) and the composite resins Filtek Z350 flow (Z) and Filtek Supreme (S), when polymerized by light-emitting diode (LED XL 3000) and quartz-tungsten halogen (QTH Biolux). Class V cavities (3 yen2 mm) were prepared in 80 bovine incisors under standardized conditions. The patients were divided as follows: G1: Control; G2: SB; G3: SB + Z; G4: SB + S. The groups were subdivided into two groups for polymerization (A: QTH, B: LED). Light curing was performed for 40 s and measurement of temperature changes during polymerization was performed with a thermocouple positioned inside the pulp chamber. Data were statistically analyzed using ANOVA and Tukey tests. The factors material (P<0.00001) and curing unit (P<0.00001) had significant influence on temperature rise. The lowest temperature increase (0.15 degrees C) was recorded in G2 B and the highest was induced in G1 A (0.75 degrees C, P<0.05). In all groups, lower pulp chamber temperature measurements were obtained when using LED compared to QTH (P<0.05). QTH caused greater increases in tooth temperature than LED. However, both sources did not increase pulpal temperature above the critical value that may cause pulpal damage.

  17. Optimized Phosphors for Warm White LED Light Engines

    Energy Technology Data Exchange (ETDEWEB)

    Setlur, Anant; Brewster, Megan; Garcia, Florencio; Hill, M. Christine; Lyons, Robert; Murphy, James; Stecher, Tom; Stoklosa, Stan; Weaver, Stan; Happek, Uwe; Aesram, Danny; Deshpande, Anirudha

    2012-07-30

    The objective of this program is to develop phosphor systems and LED light engines that have steady-state LED efficacies (using LEDs with a 60% wall-plug efficiency) of 105–120 lm/W with correlated color temperatures (CCT) ~3000 K, color rendering indices (CRI) >85, <0.003 distance from the blackbody curve (dbb), and <2% loss in phosphor efficiency under high temperature, high humidity conditions. In order to reach these goals, this involves the composition and processing optimization of phosphors previously developed by GE in combination with light engine package modification.

  18. Reliable LED Lighting Technologies: Key Factors and Procurement Guidance

    Energy Technology Data Exchange (ETDEWEB)

    Davis, Lynn; Arquit Niederberger, Anne

    2015-10-08

    Abstract— Lighting systems have the ability to transform the economic and educational infrastructure of disadvantaged communities, and eradicating “light poverty” has become one of the primary goals of the International Year of Light 2015. Solid-state lighting (SSL) technology, based on light-emitting diode (LED) light sources, has emerged as the next generation of lighting technology, with a current global market penetration of roughly 5%. This paper will report on recent research on understanding SSL lighting system reliability (failure modes, environmental stressors, electrical power quality); discuss the implications of SSL technology reliability for providing lighting services; and suggest practical approaches to ensure SSL reliability to benefit humanity. Among the key findings from this work is that LED sources can be extremely reliable, withstanding a broad range of environmental stresses without failure. Nonetheless, SSL lighting systems can have a negative impact on electrical power reliability, as well as on the affordability of lighting services, without attention to the quality of the accompanying power infrastructure. It is therefore critical to ensure that the performance of the power supply electronics used in lighting systems is matched to the quality of the power source, when evaluating energy efficient lighting choices.

  19. Marginal seal of composite resin restorations photo activated by L.E.D. and halogen-based light

    OpenAIRE

    Pineda Mejía, Martha Elena; Dpto. Acad. Estomatología Rehabilitadora. Fac. Odontologia. Universidad Nacional Mayor de San Marcos.; Terán Casafranca, Liliana Ángela; Dpto. Acad. Estomatología Rehabilitadora. Fac. Odontologia. Universidad Nacional Mayor de San Marcos.; Gloria Zevallos, Waldo Ernesto; Dpto. Acad. Estomatología Rehabilitadora. Fac. Odontologia. Universidad Nacional Mayor de San Marcos.; Cuadrao Zavaleta, Luis Alberto; Dpto. Acad. Ciencias Básicas. Fac. Odontologia. Universidad Nacional Mayor de San Marcos.

    2014-01-01

    Objective: to compare in vitro the marginal seal degree of composite resin restorations photopolomerized with L.E.D light and conventional halogen light, was the objective of this research.It was used 20 healthy molars recently extracted, in each of them, standardized dimensions class V cavities were prepared in the buccal and palatal aspects. Both cavities were filled with nanoparticles composite resin, Filteck Z350 and Single Bond adhesive (3M). Vestibular restaurations were light cured usi...

  20. Effect of shade, opacity and layer thickness on light transmission through a nano-hybrid dental composite during curing.

    Science.gov (United States)

    Hyun, Hong-Keun; Christoferson, Carly K; Pfeifer, Carmem S; Felix, Chris; Ferracane, Jack L

    2017-09-01

    The aim of this study was to investigate the effect of shade and opacity on the change in light transmission through different thicknesses of a nano-hybrid composite during curing. Twelve different shades of Venus Diamond (Heraeus Kulzer) were placed in disk shaped molds with thickness of 1, 2, and 3 mm (n = 3 per group) and cured with an LED light-curing unit. Initial, final and average irradiance, and the total amount of energy passing through the specimen were measured using the MARC Resin Calibrator at every 10s for a total of 40s. The translucency parameter and the contrast ratio were obtained using a chromameter. Results were analyzed with ANOVA/Tukey's test (α = 0.05). All shades and all thicknesses (up to 3 mm) experienced an increase in light transmittance during curing. The majority of the increase occurred during the initial 10s exposure, with significant increase occurring from subsequent exposures only in thicker specimens (i.e., 3 mm). The increase in irradiance at the bottom during curing was dependent on shade, with darker shades and greater depths of material showing less increase. For one specific resin composite formulation, an increase in translucency occurs as cure progresses, and the increase is enhanced for composites with greater lightness and lower contrast ratio. Composites demonstrate increased light transmittance as curing progress, which may improve depth of cure. The thicker composite showed the least increase in light transmission within the same shade. The increase in translucency is enhanced for composites with great lightness and lower contrast ratio. © 2017 Wiley Periodicals, Inc.

  1. LED Light to improve Strawberry Flavour, Quality and Production

    NARCIS (Netherlands)

    Hanenberg, M.A.A.; Janse, J.; Verkerke, W.

    2016-01-01

    A current demonstration in the greenhouses of Wageningen UR in Bleiswijk (the Netherlands) shows positive results of LED light on the quality and production of strawberries (Fragaria x ananassa). In this demonstration two strawberry cultivars, Elsanta and Sonata, are exposed to three different light

  2. Current-voltage model of LED light sources

    DEFF Research Database (Denmark)

    Beczkowski, Szymon; Munk-Nielsen, Stig

    2012-01-01

    Amplitude modulation is rarely used for dimming light-emitting diodes in polychromatic luminaires due to big color shifts caused by varying magnitude of LED driving current and nonlinear relationship between intensity of a diode and driving current. Current-voltage empirical model of light...

  3. Effect of Led Lighting Colors for Laying Japanese Quails

    Directory of Open Access Journals (Sweden)

    KC Nunes

    Full Text Available ABSTRACT Time of exposure and light intensity rearing house may affect the performance and egg quality of laying quails. This research aimed at evaluating the live performance, egg quality, biometry of the reproductive system, and the gastrointestinal tract of Japanese quails (Coturnix coturnix japonica exposed to artificial light-emitting diodes (LED of different colors in comparison with fluorescent lamps. A total of 240 Japanese quails were distributed in completely randomized experimental design with four treatments (fluorescent lamp, and green, red, or blue LED lamps with six replicates of 10 birds each. Average egg weight and eggshell thickness were different (p0.05. The oviduct of 64-d-old hens exposed to green LED lighting was shorter (p<0.05 than those exposed to the fluorescent lamp. Red LED can be used to replace the fluorescent lamps, as they promote the same live performance, egg quality, and morphological development of the reproductive tract of laying Japanese quails.

  4. Materials and Designs for High-Efficacy LED Light Engines

    Energy Technology Data Exchange (ETDEWEB)

    Ibbetson, James [Cree, Inc., Durham, NC (United States); Gresback, Ryan [Cree, Inc., Durham, NC (United States)

    2017-09-28

    Cree, Inc. conducted a narrow-band downconverter (NBD) materials development and implementation program which will lead to warm-white LED light engines with enhanced efficacy via improved spectral efficiency with respect to the human eye response. New red (600-630nm) NBD materials could result in as much as a 20% improvement in warm-white efficacy at high color quality relative to conventional phosphor-based light sources. Key program innovations included: high quantum yield; narrow peak width; minimized component-level losses due to “cross-talk” and light scattering among red and yellow-green downconverters; and improved reliability to reach parity with conventional phosphors. NBD-enabled downconversion efficiency gains relative to conventional phosphors yielded an end-of-project LED light engine efficacy of >160 lm/W at room temperature and 35 A/cm2, with a correlated color temperature (CCT) of ~3500K and >90 CRI (Color Rending Index). NBD-LED light engines exhibited equivalent luminous flux and color point maintenance at >1,000 hrs. of highly accelerated reliability testing as conventional phosphor LEDs. A demonstration luminaire utilizing an NBD-based LED light engine had a steady-state system efficacy of >150 lm/W at ~3500K and >90 CRI, which exceeded the 2014 DOE R&D Plan luminaire milestone for FY17 of >150 lm/W at just 80 CRI.

  5. Injecting Light of High-Power LEDs into Thin Light Guides

    NARCIS (Netherlands)

    Cornelissen, H.J.; Krijn, M.P.C.; Ma, H.; Van Sprang, H.A.

    2010-01-01

    A new method using a thin-film multilayer filter is described to couple light from high-power LEDs into a thin light guide such as an LCD backlight. Light emitted below the critical angle is reflected back to the LED and recycled. Large-angle emitted light passes the filter and is transported by

  6. [The development of light-curing soft denture liner].

    Science.gov (United States)

    Zhao, X; Shi, C

    1997-07-01

    In this study, a visible light-curing soft denture liner was developed, and 6 methacrylate polyurethane elastomer and a diluent were synthesised, their effect on tensile strength, compression set, Shore A hardness, absorption and solubility were also investigated. The results showed that the elastomer made of polyethylene adipate or polybutylene ether glycol possessed the highest tensile strength and hardness, the elastomer made of polypropylene ether glycol showed low tensile strength and low shore A hardness, the elastomer made of hydroxyl-terminated liquid polybutadiene rubber had a moderate tensile strength and hardness.

  7. Control and Driving Methods for LED Based Intelligent Light Sources

    DEFF Research Database (Denmark)

    Beczkowski, Szymon

    High power light-emitting diodes allow the creation of luminaires capable of generating saturated colour light at very high efficacies. Contrary to traditional light sources like incandescent and high-intensity discharge lamps, where colour is generated using filters, LEDs use additive light mixing......, where the intensity of each primary colour diode has to be adjusted to the needed intensity to generate specified colour. The function of LED driver is to supply the diode with power needed to achieve the desired intensity. Typically, the drivers operate as a current source and the intensity...... of the diode is controlled either by varying the magnitude of the current or by driving the LED with a pulsed current and regulate the width of the pulse. It has been shown previously, that these two methods yield different effects on diode's efficacy and colour point. A hybrid dimming strategy has been...

  8. Effect of light sources and curing mode techniques on sorption, solubility and biaxial flexural strength of a composite resin.

    Science.gov (United States)

    Carvalho, Andreia Assis; Moreira, Francine do Couto Lima; Fonseca, Rodrigo Borges; Soares, Carlos José; Franco, Eduardo Batista; Souza, João Batista de; Lopes, Lawrence Gonzaga

    2012-01-01

    Adequate polymerization plays an important role on the longevity of the composite resin restorations. The aim of this study was to evaluate the effect of light-curing units, curing mode techniques and storage media on sorption, solubility and biaxial flexural strength (BFS) of a composite resin. Two hundred and forty specimens were made of one composite resin (Esthet-X) in a stainless steel mold (2 mm x 8 mm Ø), and divided into 24 groups (n=10) established according to the 4 study factors: light-curing units: quartz tungsten halogen (QTH) lamp and light-emitting diodes (LED); energy densities: 16 J/cm² and 20 J/cm²; curing modes: conventional (CM) and pulse-delay (PD); and permeants: deionized water and 75% ethanol for 28 days. Sorption and solubility tests were performed according to ISO 4049:2000 specifications. All specimens were then tested for BFS according to ASTM F394-78 specification. Data were analyzed by three-way ANOVA followed by Tukey, Kruskal-Wallis and Mann-Whitney tests (α=0.05). In general, no significant differences were found regarding sorption, solubility or BFS means for the light-curing units and curing modes (p>0.05). Only LED unit using 16 J/cm² and PD using 10 s produced higher sorption and solubility values than QTH. Otherwise, using CM (16 J/cm²), LED produced lower values of BFS than QTH (pcuring units using 16 and 20 J/cm² by CM and PD curing modes produced no influence on the sorption, solubility or BFS of the tested resin.

  9. Application of high-brightness LEDs in aircraft position lights

    Science.gov (United States)

    Machi, Nicolo; Mangum, Scott; Singer, Jeffrey M.

    2004-10-01

    Solid state lighting devices have made their way into a number of niche markets and continue to make inroads into other markets as their price / performance ratios improve. One of these markets is aviation lighting. Although this paper will focus on the use of LEDs for aircraft position lights, much of the discussion is applicable to other installations on the interior and exterior of the aircraft. The color, light distribution and intensity levels for a position light are all closely regulated through Code of Federal Regulation (CFR; formerly Federal Aviation Regulation (FAR)) documents. These lighting requirements, along with harsh thermal and environmental requirements, drive the design. In this paper, we will look at these requirements and discuss what is required in order to use LEDs for this type of application. We will explore the optical, thermal and electrical issues associated with the use of LEDs for position lights and examine the specific case study of the Astreon forward position lights. Finally, we will discuss some of the challenges that we see with solid state lighting in current and future aircraft applications.

  10. Light-curing efficiency of dental adhesives by gallium nitride violet-laser diode determined in terms of ultimate micro-tensile strength.

    Science.gov (United States)

    Kameyama, Atsushi; Kato, Junji; De Munck, Jan; Hatayama, Hitoshi; Haruyama, Akiko; Yoshinari, Masao; Takase, Yasuaki; Van Meerbeek, Bart; Tsunoda, Masatake

    2011-01-01

    The purpose of this study was to evaluate whether violet-laser diode (VLD) can be used as light-curing source. The ultimate (micro-)tensile strength (μTS) of three adhesives was determined when cured by VLD in comparison with curing by two different types of commercial LED light-curing units. One VLD (VLM 500) and two LED units (Curenos and G-Light Prima) were used to cure the adhesive resin of the two-step self-etch adhesives Clearfil SE Bond, Tokuso Mac Bond II, and FL-Bond II. A 0.6-mm thick acrylic mould was filled with adhesive resin and cured for 60 s. After 24-h water storage, specimens were trimmed into an hourglass shape with a width of 1.2 mm at the narrowest part, after which the μTS was determined (n=10). In addition, the light transmittance of each adhesive was characterized using a UV-vis-NIR spectrometer. No significant difference in curing efficiency between VLD and LED were observed for both Tokuso Mac Bond II and FL-Bond II (p>0.05). For Clearfil SE Bond, the μTS of VLD-cured specimens was higher than that of the specimens cured by the LED Curenos unit (plight transmittance of Clearfil SE Bond for visible blue light versus for the lower area of UV and visible violet light. In conclusion, A GaN-based violet laser diode can be used as light-curing source to initiate polymerization of dental resins.

  11. Light out-coupling from LEDs by means of metal nanoparticles; Lichtauskopplung aus LEDs mittels Metallnanoteilchen

    Energy Technology Data Exchange (ETDEWEB)

    Goehler, Tino

    2010-12-17

    The external quantum efficiency of light-emitting diodes (LEDs) based on Al- GaAs/InGaAlP is limited by total internal reflection because of the high refractive index (typically between 3 and 4) of the semiconductor. Metal nanoparticles (MNP) deposited on the surface of the LED can be used as dipole scatterers in order to enhance the emission of the LED. In this thesis, first, single gold nanoparticles of various sizes deposited on such an LED were investigated. A clear enhancement is detected as long as the dipole plasmon resonance of the particle is at a shorter wavelength than the LED emission. If the plasmon resonance coincides with the LED emission or is at a larger wavelength, the enhancement turns into suppression. Numerical simulations indicate that this latter effect is mainly caused by the particle quadrupole resonance producing extra absorption. Arrays of MNPs can be produced by a special mask technique called ''Fischer pattern nanolithography'' and manipulated in shape and size by additional steps. Originally, the MNPs produced by this technique are triangular in shape and turn out to suppress the LED emission. After transformation of the particles to spheres, a clear enhancement was detected. Light that would otherwise remain trapped inside the substrate is coupled out by resonant plasmonic scattering. Investigations on analogous structures on a transparent high-index material (GaP) indicate a stronger coupling between the particles than expected on the basis of literature data. (orig.)

  12. Light-curing considerations for resin-based composite materials: a review. Part II.

    Science.gov (United States)

    Malhotra, Neeraj; Mala, Kundabala

    2010-10-01

    As discussed in Part I, the type of curing light and curing mode impact the polymerization kinetics of resin-based composite (RBC) materials. Major changes in light-curing units and curing modes have occurred. The type of curing light and mode employed affects the polymerization shrinkage and associated stresses, microhardness, depth of cure, degree of conversion, and color change of RBCs. These factors also may influence the microleakage in an RBC restoration. Apart from the type of unit and mode used, the polymerization of RBCs is also affected by how a light-curing unit is used and handled, as well as the aspects associated with RBCs and the environment. Part II discusses the various clinical issues that should be considered while curing RBC restorations in order to achieve the best possible outcome.

  13. A summary of LED lighting impacts on health

    Directory of Open Access Journals (Sweden)

    Cosmin Ticleanu

    2017-06-01

    Full Text Available Lighting can affect the health of people in buildings. This goes beyond the safety aspects of providing enough illumination to see by; lighting affects mood and human circadian rhythms, while poor lighting can cause glare, headaches, eyestrain, aches and pains associated with poor body posture or, in extreme cases, skin conditions and various types of sight loss. These aspects ought to be considered by designers and building owners and occupiers in order to improve the lit environment and use adequate lighting and lighting controls that meet the recommendations of codes and standards. Various types of lighting can have different impacts depending on their spectral, optical and electrical characteristics. This paper discusses potential impacts of LED lighting on human health, and is based on a recent BRE review of research investigating the most typical effects of lighting on human health.

  14. LED Street Lighting Solutions: Flagstaff, Arizona as a Case Study

    Science.gov (United States)

    Hall, Jeffrey C.

    2018-01-01

    Dark-sky protection in Flagstaff, Arizona extends back to 1958, with the first ordinance in the City banning advertising floodlights. The current ordinance, adopted in 1989, is comprehensive and has played a critical role in maintaining the quality of the night sky for astronomy, tourism, public enjoyment, and other purposes. Flagstaff, like many communities around the world, is now working on a transition from legacy bulb-based technology to LED for its outdoor lighting. The City, Lowell Observatory, the U. S. Naval Observatory, and the Flagstaff Dark Skies Coalition have been working intensively for two years to identify an LED-based street lighting solution that will preserve the City's dark skies while meeting municipal needs. We will soon be installing test fixtures for an innovative solution incorporating narrow-band amber LED and modest amounts of low-CCT white LED. In this talk, I will review the types of LEDs available for outdoor lighting and discuss the plans for Flagstaff's street lighting in the LED era, which we hope will be a model for communities worldwide.

  15. An Integrated Solid-State LED Luminaire for General Lighting

    Energy Technology Data Exchange (ETDEWEB)

    Kevin Dowling; Fritz Morgan Ihor Lys; Mike Datta; Bernd Keller; Thomas Yuan

    2009-03-31

    A strong systems approach to designing and building practical LED-based replacement lamps is lacking. The general method of taking high-performance LEDs and marrying them to standard printed circuit boards, drivers and a heat sink has fallen short of the promise of LED lighting. In this program, a top-down assessment of requirements and a bottom-up reinvention of LED sources, electronics, optics and mechanics have resulted in the highest performance lamp possible. The team, comprised of Color Kinetics, the leaders in LED lighting and Cree, the leaders in LED devices took an approach to reinvent the package, the driver and the overall form and aesthetic of a replacement source. The challenge was to create a new benchmark in LED lighting - the resultant lamp, a PAR38 equivalent, met the light output, color, color quality and efficacy marks set out in the program as well as being dimmable, which is important for market acceptance. The approach combined the use of multiple source die, a chip-on-board approach, a very efficient driver topology, the use of both direct emission and phosphor conversion, and a unique faceted optic to avoid the losses, artifacts and hotspots of lensed approaches. The integral heat sink provided a mechanical base and airflow using a chimney-effect for use in a wide variety of locations and orientations. These research results led to a much better understanding of the system effects of component level technologies. It was clear that best-of-breed sub-system results do not necessarily result in the best end result for the complete system. In doing this work, we did not neglect the practical aspects of these systems. These were not rarified results and commercially impractical but lent themselves to eventual commercial products in the marketplace. The end result - a high performance replacement lamp - will save significant energy while providing a high-quality light source.

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

    International Nuclear Information System (INIS)

    Bergh, Arpad A.

    2004-01-01

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

  17. Surface energy and wettability of polymers light-cured by two different systems

    Directory of Open Access Journals (Sweden)

    Fatima Maria Namen

    2011-10-01

    Full Text Available OBJECTIVE: This study evaluated the surface energy and wettability of composite resins polymerized by different light-curing units to ascertain the good wetting of tooth surfaces to achieve adhesion. MATERIAL AND METHOD: Filtek Z350 (3M ESPE, Admira (VOCO and Grandio (VOCO resins were selected for the testing procedures. The resins were light cured using LED and Halogen devices. Contact angles were measured goniometrically (Ramé-Hart F100 using water and glycerol as test liquids. Surface energy values were calculated with a software program (DROPimage Standard that uses the harmonic mean method applied to the acid-base theory. The data were analyzed statistically by ANOVA and Tukey's test with a significance of 0.05. RESULTS AND CONCLUSIONS: No statistically significant differences were found between the values of surface energy. The measured wettability differed statistically in most combinations as a function of the type of composite resin, type of light-curing unit, and the test liquid.

  18. Effect of curing light emission spectrum on the nanohardness and elastic modulus of two bulk-fill resin composites.

    Science.gov (United States)

    Issa, Yaser; Watts, David C; Boyd, Daniel; Price, Richard B

    2016-04-01

    To determine the nanohardness and elastic moduli of two bulk-fill resin based composites (RBCs) at increasing depths from the surface and increasing distances laterally from the center after light curing. Two bulk-fill dental RBCs: Tetric EvoCeram Bulk Fill (TECBF) and Filtek Bulk Fill Flowable (FBFF) were light cured in a metal mold with a 6mm diameter and a 10mm long semi-circular notch. The RBCs were photo-polymerized for 10s using a light emitting diode (LED) Bluephase Style curing light, with the original light probe that lacked the homogenizer. This light has two blue light and one violet light LED emitters. By changing the probe orientation over the mold, the light output from only two LEDs reached the RBC. Measurements were made using: (i) the light from one violet and one blue LED, and (ii) the light from the two blue LEDs. Five specimens of each RBC were made using each LED orientation (total 20 specimens). Specimens were then stored in the dark at 37°C for 24h. Fifty indents were made using an Agilent G200 nanoindentor down to 4mm from the surface and 2.5mm right and left of the centerline. The results were analyzed (alpha=0.05) using multiple paired-sample t-tests, ANOVA, Bonferroni post-hoc tests, and Pearson correlations. The elastic modulus and nanohardness varied according to the depth and the distance from the centerline. For TECBF, no significant difference was found between the spatial variations in the elastic modulus or hardness values when violet-blue or blue-blue LEDs were used. For FBFF, the elastic modulus and nanohardness on the side exposed to the violet emitter were significantly less than the side exposed to the blue emitter. A strong correlation between nanohardness and elastic modulus was found in all groups (r(2)=0.9512-0.9712). Resin polymerization was not uniform throughout the RBC. The nanohardness and elastic modulus across two RBC materials were found to decline differently according to the orientation of the violet and blue

  19. Progress in extremely high brightness LED-based light sources

    Science.gov (United States)

    Hoelen, Christoph; Antonis, Piet; de Boer, Dick; Koole, Rolf; Kadijk, Simon; Li, Yun; Vanbroekhoven, Vincent; Van De Voorde, Patrick

    2017-09-01

    Although the maximum brightness of LEDs has been increasing continuously during the past decade, their luminance is still far from what is required for multiple applications that still rely on the high brightness of discharge lamps. In particular for high brightness applications with limited étendue, e.g. front projection, only very modest luminance values in the beam can be achieved with LEDs compared to systems based on discharge lamps or lasers. With dedicated architectures, phosphor-converted green LEDs for projection may achieve luminance values up to 200-300 Mnit. In this paper we report on the progress made in the development of light engines based on an elongated luminescent concentrator pumped by blue LEDs. This concept has recently been introduced to the market as ColorSpark High Lumen Density LED technology. These sources outperform the maximum brightness of LEDs by multiple factors. In LED front projection, green LEDs are the main limiting factor. With our green modules, we now have achieved peak luminance values of 2 Gnit, enabling LED-based projection systems with over 4000 ANSI lm. Extension of this concept to yellow and red light sources is presented. The light source efficiency has been increased considerably, reaching 45-60 lm/W for green under practical application conditions. The module architecture, beam shaping, and performance characteristics are reviewed, as well as system aspects. The performance increase, spectral range extensions, beam-shaping flexibility, and cost reductions realized with the new module architecture enable a breakthrough in LED-based projection systems and in a wide variety of other high brightness applications.

  20. County of Hawaii - A Unique LED Street Light Conversion

    Science.gov (United States)

    Thiel, Ronald LeRoy

    2015-08-01

    In 2010 the County of Hawaii was paying $0.40/kW-Hr for electricity, $1.5 mil annual bill for 8,500 street lights. Over the past 20 years costs have increased on an average of 7% per year. Inventory maintenance frequency for the 8,500 lights was 35%, which meant 3,000 visits per year. The current LPS street lights were nearing 20 years of service and a complete replacement was imminent, a significant cost for the County of Hawaii and its 185,000 citizens.The astronomy community impact was identified early on and discussions conducted for an acceptable conversion path. Key concerns centered on the blue light content of the LED and reflected light.A demo project with Federal ARRA funds installed 1,000 LED full cut off fixtures achieving an energy savings of $200K annually. The results were extremely successful and were loudly applauded by both the general public and the Astronomy Institute. Hence, the Traffic Division recommended to the County administration changing the remaining lights, now numbering 9,000, to new LED lights. The County administration approved the change to the LED lights and an upgrade to the outdoor lighting ordinance.The remainder of the conversion, amounting to $6 million for materials and labor, is expected to yield an energy savings of approximately $800K annually with a 5 year recovery of costs that includes both energy savings and maintenance reduction.Additional benefits achieved from using full cutoff fixtures include reduction in glare for drivers, pedestrians, and elimination of trespass light onto neighboring residences.Benefits achieved by using a filtered LED includes reducing blue light to <1 %, diffusing the harshness of the direct LED light and the ability to use the most energy efficient lumen producing fixture to achieve in excess of 63% reduction in energy costs.Additional aspects of this conversion presentation will include steps to gather quantitative data showing reduction in light pollution, aerial and satellite surveys for

  1. Effect of preheating and light-curing unit on physicochemical properties of a bulk fill composite

    Directory of Open Access Journals (Sweden)

    Theobaldo JD

    2017-05-01

    Full Text Available Jéssica Dias Theobaldo,1 Flávio Henrique Baggio Aguiar,1 Núbia Inocencya Pavesi Pini,2 Débora Alves Nunes Leite Lima,1 Priscila Christiane Suzy Liporoni,3 Anderson Catelan3 1Department of Restorative Dentistry, Piracicaba Dental School, University of Campinas, Piracicaba, 2Ingá University Center, Maringá, 3Departament of Dentistry, University of Taubaté, Taubaté, Brazil Objective: The aim of this study is to evaluate the effect of composite preheating and polymerization mode on degree of conversion (DC, microhardness (KHN, plasticization (P, and depth of polymerization (DP of a bulk fill composite.Methods: Forty disc-shaped samples (n = 5 of a bulk fill composite were prepared (5 × 4 mm thick and randomly divided into 4 groups according to light-curing unit (quartz–tungsten–halogen [QTH] or light-emitting diode [LED] and preheating temperature (23 or 54 °C. A control group was prepared with a flowable composite at room temperature. DC was determined using a Fourier transform infrared spectrometer, KHN was measured with a Knoop indenter, P was evaluated by percentage reduction of hardness after 24 h of ethanol storage, and DP was obtained by bottom/top ratio. Data were statistically analyzed by analysis of variance and Tukey’s test (α = 0.05.Results: Regardless of light-curing, the highest preheating temperature increased DC compared to room temperature on bottom surface. LED showed a higher DC compared to QTH. Overall, DC was higher on top surface than bottom. KHN, P, and DP were not affected by curing mode and temperature, and flowable composite showed similar KHN, and lower DC and P, compared to bulk fill.Conclusion: Composite preheating increased the polymerization degree of 4-mm-increment bulk fill, but it led to a higher plasticization compared to the conventional flowable composite evaluated. Keywords: composite resins, physicochemical phenomena, polymerization, hardness, heating

  2. LED street lighting evaluation -- phase II : LED specification and life-cycle cost analysis.

    Science.gov (United States)

    2015-01-01

    Phase II of this study focused on developing a draft specification for LED luminaires to be used by IDOT : and a life-cycle cost analysis (LCCA) tool for solid state lighting technologies. The team also researched the : latest developments related to...

  3. Effect of light-curing units in shear bond strength of metallic brackets: an in vitro study

    Directory of Open Access Journals (Sweden)

    Luciana Borges Retamoso

    2010-02-01

    Full Text Available OBJECTIVES: To determine the influence of the light curing units on the shear bond strength of orthodontic brackets. MATERIAL AND METHODS: Seventy-two premolars were divided into six groups (n=12: Group I: brackets bonded with Transbond and polymerization with halogen light; Group II: Transbond and LED; Group III: Fuji Ortho and halogen light; Group IV: Fuji Ortho and LED; Group V: Fuji Ortho, without acid and halogen light; Group VI: Fuji Ortho, without acid and LED. The groups were tested to shear strength in a universal testing machine at a crosshead speed of 0.5 mm/min. Data were analyzed statistically by ANOVA and Tukey's test. RESULTS: The composite resin presented higher shear bond strength than the resin-modified glass ionomer cement (p0.05. CONCLUSION: The shear bond strength was influenced by the material but not by the light-curing unit. The use of LED reduced the experimental time by approximately 60%, with the same curing efficiency.

  4. Monte carlo analysis of multicolour LED light engine

    DEFF Research Database (Denmark)

    Chakrabarti, Maumita; Thorseth, Anders; Jepsen, Jørgen

    2015-01-01

    A new Monte Carlo simulation as a tool for analysing colour feedback systems is presented here to analyse the colour uncertainties and achievable stability in a multicolour dynamic LED system. The Monte Carlo analysis presented here is based on an experimental investigation of a multicolour LED...... light engine designed for white tuneable studio lighting. The measured sensitivities to the various factors influencing the colour uncertainty for similar system are incorporated. The method aims to provide uncertainties in the achievable chromaticity coordinates as output over the tuneable range, e...

  5. High quality Danish design with intelligent LED light. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Petersen, Paul Michael; Dam-Hansen, C.; Thestrup, B.; Pedersen, Henrik (Technical Univ. of Denmark, DTU Fotonik, Roskilde (Denmark)); Olsen, Jesper (JesperOlsen ApS, Frederiksberg (Denmark)); Falleboe, H.; Andersen, Jakob (MORFOSO, Copenhagen (Denmark))

    2010-02-15

    Based on the results achieved in a previous project, which enabled a number of designers to be trained in the potential of LED lighting technology, this project developed intelligent LED fixtures for work purposes and for private homes. The two types of fixtures both meet the original project objective of good colour rendition with Ra indices above 90 and colour temperatures variable within the interval 3,300 to 4,400 K. Furthermore, with luminous efficacies of 60 lumen/W, both fixtures have energy efficiencies exceeding that of an average energy-friendly light source. (ln)

  6. Effect of different blue light-curing systems on the polymerization of nanocomposite resins.

    Science.gov (United States)

    Jang, Chang-Min; Seol, Hyo-Joung; Kim, Hyung-Ii; Kwon, Yong Hoon

    2009-12-01

    To examine the degree of polymerization of nanocomposite resins to test the possibility of using a diode-pumped solid state (DPSS) laser as a light-curing source on behalf of the argon laser. DPSS lasers emitting light at 473 nm have many advantages over argon lasers on account of their compactness, efficiency, and price. A 473-nm DPSS laser (LAS) was used with three other light-curing units (a quartz-tungsten-halogen lamp-based unit, a light emitting diode-based unit, and a xenon lamp-based plasma arc unit) to polymerize dental nanocomposite resins. The degree of polymerization was determined by measuring the microhardness, maximum polymerization shrinkage, and increase in temperature during and after light curing. The results were analyzed statistically. The specimens light cured with LAS showed a microhardness that was similar or superior to the values obtained from the specimens cured with the other light-curing units and maximum polymerization shrinkage values. The maximum increase in temperature by LAS was much lower than that induced by the other light-curing units. LAS effectively polymerizes dental nanocomposite resins to an extent similar to that of recently available light-curing units. The results suggest that LAS has good potential as a light source for light curing of dental nanocomposite resins.

  7. Microhardness of composite resin cured through different primary tooth thicknesses with different light intensities and curing times: In vitro study.

    Science.gov (United States)

    Mazhari, Fatemeh; Ajami, Behjatolmolok; Moazzami, Saied Mostafa; Baghaee, Bahareh; Hafez, Bahareh

    2016-01-01

    The aim of this study was to evaluate the effect of increased exposure time and light intensity on microhardness of cured composite through different thicknesses of tooth structure in primary teeth. One hundred and seventy cylindrical resin composite specimens were prepared. All specimens were divided into 17 experimental and control groups. "Light-emitting diode" light curing unit (LCU) applied directly or through 1, 2, and 3 mm thicknesses tooth slices for experimental groups. The irradiation protocols were 25 and 50 s at 650 mW/cm(2) and 15 and 30 s at 1100 mW/cm(2). The "quartz-tungsten-halogen" LCU (400 mW/cm(2)) for 40 s was used in control group. Microhardness was measured by the Vickers hardness test. Indirectly cured specimens and those cured through a 1 mm thick tooth structure, an increase in intensity caused hardness drop. In the specimens cured through 2 and 3 mm thick tooth structures, increased intensity and/or exposure time did not show any appropriate changes on microhardness. Irradiation through a 1.0 mm thick tooth slice resulted in reduced microhardness although it was still within the clinically acceptable level. The hardness values of the specimens cured through 2 or 3 mm thick tooth slices fell below the clinically acceptable level even after doubling the exposure time and/or light intensity.

  8. Universal fixture design for body mounted LED lights

    Science.gov (United States)

    Hajra, Debdyut

    2017-09-01

    Today LED headlamps, armbands and ankle-bands, shoe-lights etc. have become very popular. These find extensive use in search and rescue operations, mining, carving, etc. and are also used by individuals during hiking, trekking, running, etc. during dark hours. They serve two main purposes: they provide sufficient illumination in low light conditions and they are used to indicate the presence of a person after dark. These have the same basic requirements. They must produce sufficient light, have high durability, long battery life, must be light weight and energy efficient. This paper discusses possibilities of designing a universal LED fixture can be designed so that it meets the respective needs of everyone irrespective of their background and industry. It discusses the materials to be used for its different body parts, innovative clip design for attachment with support structures like head and armbands, helmets, shoes, etc.

  9. Micro-leakage of a Fissure Sealant Cured Using Quartz-tungsten-halogen and Plasma Arc Light Curing Units.

    Science.gov (United States)

    Bahrololoomi, Zahra; Soleimani, Ali Asghar; Jafari, Najmeh; Varkesh, Bentolhoda

    2014-01-01

    Background and aims. Newer curing units such as plasma arc can polymerize the sealants in much shorter curing times. The aim of this study was to compare the effect of two different curing units on the micro-leakage of a fissure sealant material. Materials and methods. Sixty two extracted premolars without caries were randomly divided into two groups of 31 samples. Occlusal surfaces of all teeth were cleansed. Then, teeth surfaces were etched by 37% phosphoric acid. After rinsing and drying, occlusal surfaces of teeth were sealed by a fissure sealant. The sealant was then cured using either a halogen light curing unit or a plasma arc curing light. After sealing, the teeth were thermocycled for 500 cycles. The teeth were then sectioned and examined for micro-leakage. Statistical analyses were performed with Mann-Whitney test. Results. There was no significant difference between two groups regarding micro-leakage (P = 0.42). Conclusion. Results showed that there was no significant difference between two different curing units. Therefore, plasma arc unit might be a useful alternative for sealant polymerization.

  10. Micro-leakage of a Fissure Sealant Cured Using Quartz-tungsten-halogen and Plasma Arc Light Curing Units

    Directory of Open Access Journals (Sweden)

    Zahra Bahrololoomi

    2014-12-01

    Full Text Available Background and aims. Newer curing units such as plasma arc can polymerize the sealants in much shorter curing times. The aim of this study was to compare the effect of two different curing units on the micro-leakage of a fissure sealant material. Materials and methods. Sixty two extracted premolars without caries were randomly divided into two groups of 31 samples. Occlusal surfaces of all teeth were cleansed. Then, teeth surfaces were etched by 37% phosphoric acid. After rinsing and drying, occlusal surfaces of teeth were sealed by a fissure sealant. The sealant was then cured using either a halogen light curing unit or a plasma arc curing light. After sealing, the teeth were thermocycled for 500 cycles. The teeth were then sectioned and examined for micro-leakage. Statistical analyses were performed with Mann-Whitney test. Results. There was no significant difference between two groups regarding micro-leakage (P = 0.42. Conclusion. Results showed that there was no significant difference between two different curing units. Therefore, plasma arc unit might be a useful alternative for sealant polymerization.

  11. A color management system for multi-colored LED lighting

    DEFF Research Database (Denmark)

    Chakrabarti, Maumita; Thorseth, Anders; Jepsen, Jørgen

    2015-01-01

    A new color control system is described and implemented for a five–color LED light engine, covering a wide white gamut. The system combines a new way of using pre-calibrated look-up tables and a rule-based optimization of chromaticity distance from the Planckian locus with a calibrated color sensor...

  12. Interaction of LED light with coinitiator-containing composite resins: effect of dual peaks.

    Science.gov (United States)

    Sim, Jae-Seong; Seol, Hyo-Joung; Park, Jeong-Kil; Garcia-Godoy, Franklin; Kim, Hyung-Il; Kwon, Yong Hoon

    2012-10-01

    Recently the colour stability of composite resins has been an issue due to the emphasis on the aesthetics of restored teeth. The purpose of the present study was to investigate how dual-peak LED units affect the polymerization of coinitiator-containing composite resins. Five composite resins [coinitiator-containing: Aelite LS Posterior (AL), Tetric EvoCeram (TE), and Vit-l-escence (VI); only CQ-containing: Grandio (GD) and Filtek Z350 (Z3)] were light cured using four different light-curing units (LCUs). Among them, Bluephase G2 (BP) and G-light (GL) were dual-peak LED LCUs. Microhardness, polymerization shrinkage, flexural, and compressive properties were measured. BP and GL had no consistent effect on the microhardness of AL, TE, and VI on the top and bottom surfaces of resin specimens. Among the specimens, AL and VI showed the least (9.86-10.41 μm) and greatest (17.58-19.21 μm) polymerization shrinkage, respectively. However, the effect of BP and GL on the shrinkage of specimens was not consistent. Among the specimens, GD showed the greatest flexural properties [strength (FS) and modulus (FM)] and TE showed the lowest flexural and compressive properties [strength (CS) and modulus (CM)]. In same resin product, maximum FS and CS differences due to the different LCUs were 10.3-21.0% and 3.6-9.2%, respectively. Furthermore, the influences of BP and GL on FS and CS were not consistent. The tested dual-peak LED LCUs had no consistent synergic effect on the polymerization of coinitiator-containing composite resins as compared with QTH and single-peak LED LCUs. The dual-peak LED LCUs achieve a similar degree of polymerization in coinitiator-composite resins as QTH and single-peak LED LCUs did. Choice of LCU does not appear to be a determinant of the light curing of coinitiator-composite resins. Copyright © 2012 Elsevier Ltd. All rights reserved.

  13. Odontological light-emitting diode light-curing unit beam quality

    Science.gov (United States)

    de Magalhães Filho, Thales Ribeiro; Weig, Karin de Mello; Werneck, Marcelo Martins; da Costa Neto, Célio Albano; da Costa, Marysilvia Ferreira

    2015-05-01

    The distribution of light intensity of three light-curing units (LCUs) to cure the resin-based composite for dental fillings was analyzed, and a homogeneity index [flat-top factor (FTF)] was calculated. The index is based on the M2 index, which is used for laser beams. An optical spectrum analyzer was used with an optical fiber to produce an x-y power profile of each LCU light guide. The FTF-calculated values were 0.51 for LCU1 and 0.55 for LCU2, which was the best FTF, although it still differed greatly from the perfect FTF=1, and 0.27 for LCU3, which was the poorest value and even lower than the Gaussian FTF=0.5. All LCUs presented notably heterogeneous light distribution, which can lead professionals and researchers to produce samples with irregular polymerization and poor mechanical properties.

  14. Effect of light-curing units on microleakage under dental composite resins

    Science.gov (United States)

    Queiroz, R. S.; Bandéca, M. C.; Calixto, L. R.; Saade, E. G.; Nadalin, M. R.; Andrade, M. F.; Porto-Neto, S. T.

    2009-09-01

    The aim of this study was to determine the effect of two light-curing units (QTH and LED) on microleakage of Class II composite resin restorations with dentin cavosurface margins. Twenty extracted mandibular first premolars, free of caries and fractures were prepared two vertical “slot” cavities in the occluso-mesial and -destal surfaces (2 mm buccal-lingually, 2 mm proximal-axially and cervical limit in enamel) and divided into 4 equal groups ( n = 8): GI and GII: packable posterior composite light-activated with LED and QTH, respectively; GIII and GIV: micro-hybrid composite resin light-activated with LED and QTH, respectively. The composite resins were applied following the manufacturer’s instructions. After 24 h of water storage specimens were subjected to thermocycling for a total of 500 cycles at 5 and 55°C and the teeth were then sealed with impermeable material. Teeth were immersed in 0.5% Basic fuchsin during 24 h at room temperature, and zero to three levels of penetration score were attributed. The Mann-Whitney and Kruskal-Wallis tests showed significant statistically similar ( P > 0.05) from GI to GII and GIII to GIV, which the GII (2.750) had the highest mean scores and the GIII and GIV (0.875) had lowest mean scores. The use of different light-curing units has no influence on marginal integrity of Class II composite resin restorations and the proprieties of composite resins are important to reduce the microleakage.

  15. Investigation of Light-Emitting Diode (LED) Point Light Source Color Visibility against Complex Multicolored Backgrounds

    Science.gov (United States)

    2017-11-01

    ARL-TR-8214 ● NOV 2017 US Army Research Laboratory Investigation of Light-Emitting Diode (LED) Point Light Source Color...ARL-TR-8214 ● NOV 2017 US Army Research Laboratory Investigation of Light-Emitting Diode (LED) Point Light Source Color Visibility against...instructions, searching existing data sources , gathering and maintaining the data needed, and completing and reviewing the collection information. Send

  16. A PREP Panel, Practice-Based, Evaluation of the Handling of the Kerr Demi-Ultra Light Curing Unit.

    Science.gov (United States)

    Burke, F J Trevor; Crisp, Russell J

    2015-09-01

    This paper describes the handling evaluation (by a group of practice-based researchers, the PREP Panel) of a recently introduced Light Curing Unit (LCU), the Kerr Demi-Ultra, which possesses a number of novel features such as its ultracapacitor power source, and the Light Emitting Diodes (LEDs) which provide the light output being placed close to the tip of the light guide. CPD/CLINICAL RELEVANCE: Testing of new devices and materials with respect to their handling is of importance, given that an easy to handle device should produce better clinical results than one which is difficult to use.

  17. 78 FR 5207 - Certain Led Photographic Lighting Devices and Components Thereof; Commission's Final...

    Science.gov (United States)

    2013-01-24

    ... COMMISSION Certain Led Photographic Lighting Devices and Components Thereof; Commission's Final Determination... general exclusion order prohibiting importation of infringing LED photographic lighting devices and... importation of certain LED photographic lighting devices and components thereof that infringe certain claims...

  18. High-Voltage LED Light Engine with Integrated Driver

    Energy Technology Data Exchange (ETDEWEB)

    Soer, Wouter [Lumileds LLC, San Jose, CA (United States)

    2016-02-29

    LED luminaires have seen dramatic changes in cost breakdown over the past few years. The LED component cost, which until recently was the dominant portion of luminaire cost, has fallen to a level of the same order as the other luminaire components, such as the driver, housing, optics etc. With the current state of the technology, further luminaire performance improvement and cost reduction is realized most effectively by optimization of the whole system, rather than a single component. This project focuses on improving the integration between LEDs and drivers. Lumileds has developed a light engine platform based on low-cost high-power LEDs and driver topologies optimized for integration with these LEDs on a single substrate. The integration of driver and LEDs enables an estimated luminaire cost reduction of about 25% for targeted applications, mostly due to significant reductions in driver and housing cost. The high-power LEDs are based on Lumileds’ patterned sapphire substrate flip-chip (PSS-FC) technology, affording reduced die fabrication and packaging cost compared to existing technology. Two general versions of PSS-FC die were developed in order to create the desired voltage and flux increments for driver integration: (i) small single-junction die (0.5 mm2), optimal for distributed lighting applications, and (ii) larger multi-junction die (2 mm2 and 4 mm2) for high-power directional applications. Two driver topologies were developed: a tapped linear driver topology and a single-stage switch-mode topology, taking advantage of the flexible voltage configurations of the new PSS-FC die and the simplification opportunities enabled by integration of LEDs and driver on the same board. A prototype light engine was developed for an outdoor “core module” application based on the multi-junction PSS-FC die and the single-stage switch-mode driver. The light engine meets the project efficacy target of 128 lm/W at a luminous flux

  19. LED lighting increases the ecological impact of light pollution irrespective of color temperature.

    Science.gov (United States)

    Pawson, S M; Bader, M K-F

    Recognition of the extent and magnitude of night-time light pollution impacts on natural ecosystems is increasing, with pervasive effects observed in both nocturnal and diurnal species. Municipal and industrial lighting is on the cusp of a step change where energy-efficient lighting technology is driving a shift from “yellow” high-pressure sodium vapor lamps (HPS) to new “white” light-emitting diodes (LEDs). We hypothesized that white LEDs would be more attractive and thus have greater ecological impacts than HPS due to the peak UV-green-blue visual sensitivity of nocturnal invertebrates. Our results support this hypothesis; on average LED light traps captured 48% more insects than were captured with light traps fitted with HPS lamps, and this effect was dependent on air temperature (significant light × air temperature interaction). We found no evidence that manipulating the color temperature of white LEDs would minimize the ecological impacts of the adoption of white LED lights. As such, large-scale adoption of energy-efficient white LED lighting for municipal and industrial use may exacerbate ecological impacts and potentially amplify phytosanitary pest infestations. Our findings highlight the urgent need for collaborative research between ecologists and electrical engineers to ensure that future developments in LED technology minimize their potential ecological effects.

  20. Design for The Indoor Visible Light Communication Application System Based on LED Visible Light

    Directory of Open Access Journals (Sweden)

    Lian Wenyu

    2017-01-01

    Full Text Available This paper designs an indoor visible light communication application system based on LED. The system can modulate the original signal one or more times, move to a specific frequency band, transmit on the power line, in the LED terminal use this module to decode, restore the Ethernet signals. This design is applicable to the simplicity of the LED visible light communication applications, which provide the premise and guarantee for the construction of smart home network.

  1. ANALYSIS OF GAP FORMATION AT TOOTH-COMPOSITE RESIN INTERFACE: EFFECT OF C-FACTOR AND LIGHT-CURING PROTOCOL

    Science.gov (United States)

    dos Santos, Gustavo Oliveira; da Silva, Antônio Henrique Monteiro da Fonseca Thomé; Guimarães, José Guilherme Antunes; Barcellos, Alexandre de Araújo Lima; Sampaio, Eduardo Martins; da Silva, Eduardo Moreira

    2007-01-01

    Objective: The aim of this study was to evaluate the effect of C-factor and light-curing protocol on gap formation in composite resin restorations. Material and Methods: Cylindrical cavities with 5.0 mm diameter and three different depths (A=1.0, B=2.0 and C=3.0 mm) were prepared on the occlusal surface of 30 human molars and restored in a single increment with P 60. The composite resin was light-cured according to two protocols: standard - 850 mW/cm2 / 20 s and gradual - 100 up to 1000 mW/cm2/ 10 s + 1000 mW/cm2 / 10 s. After storage in distilled water (37°C/7 days), the restorations were cut into three slices in a buccolingual direction and the gap widths were analyzed using a 3D-scanning system. The data were submitted to ANOVA and Student-Newman-Keuls test (α=0.05). Results: ANOVA detected a significant influence for the C-factor and light-curing protocol as independent factors, and for the double interaction C-factor vs. light-curing protocol. Cavities with higher C-factor presented the highest gap formation. The gradual light-curing protocol led to smaller gap formation at cavity interfaces. Conclusions: The findings of this study suggest that the C-factor played an essential role in gap formation. The gradual light-curing protocol may allow relaxation of composite resin restoration during polymerization reaction. PMID:19089143

  2. Analysis of gap formation at tooth-composite resin interface: effect of C-factor and light-curing protocol

    Directory of Open Access Journals (Sweden)

    Gustavo Oliveira dos Santos

    2007-08-01

    Full Text Available OBJECTIVE: The aim of this study was to evaluate the effect of C-factor and light-curing protocol on gap formation in composite resin restorations. Material and METHODS: Cylindrical cavities with 5.0 mm diameter and three different depths (A=1.0, B=2.0 and C=3.0 mm were prepared on the occlusal surface of 30 human molars and restored in a single increment with P 60. The composite resin was light-cured according to two protocols: standard - 850 mW/cm² / 20 s and gradual - 100 up to 1000 mW/cm² / 10 s + 1000 mW/cm² / 10 s. After storage in distilled water (37°C/7 days, the restorations were cut into three slices in a buccolingual direction and the gap widths were analyzed using a 3D-scanning system. The data were submitted to ANOVA and Student-Newman-Keuls test (alpha=0.05. RESULTS: ANOVA detected a significant influence for the C-factor and light-curing protocol as independent factors, and for the double interaction C-factor vs. light-curing protocol. Cavities with higher C-factor presented the highest gap formation. The gradual light-curing protocol led to smaller gap formation at cavity interfaces. CONCLUSIONS: The findings of this study suggest that the C-factor played an essential role in gap formation. The gradual light-curing protocol may allow relaxation of composite resin restoration during polymerization reaction.

  3. Demonstration of LED Street Lighting in Kansas City, MO

    Energy Technology Data Exchange (ETDEWEB)

    Kinzey, Bruce R.; Royer, Michael P.; Hadjian, M.; Kauffman, Rick

    2013-06-10

    Nine different streetlighting products were installed on various streets in Kansas City, Missouri during February, 2011, to evaluate their performance relative to the incumbent high-pressure sodium (HPS) lighting. The applications investigated included 100 W, 150 W, 250 W, and 400 W HPS installations. Initial measurements and comparisons included power, illuminance, and luminance; sample illuminance readings have continued at each of the nine locations at roughly 1,000-hour operating intervals since then. All of the LED products consumed less power than their HPS counterparts—with a mean difference of 39% and a range of 31% to 51%—but they also emitted 31% fewer lumens, on average. The net result is just a 15% increase in mean efficacy. Applying the city’s stringent light loss factors to the initial measured data meant that five of the LED products (and two of the HPS luminaires) were predicted to eventually fail to meet the specified mean illuminance over their lifetimes; however, the specified light loss levels are not expected to be reached by the LED products until some distant future date (between 12 and 30 years after installation according to manufacturer specification sheet estimates). The practical value of designing streetlighting systems to meet illumination requirements more than 15 years in the future is questioned. Numerous sources of variation in field measurements are noted throughout the report, particularly seasonal influences such as ambient temperature and foliage that are evident in the time-series illuminance data.

  4. Influence of curing time, overlay material and thickness on three light-curing composites used for luting indirect composite restorations.

    Science.gov (United States)

    D'Arcangelo, Camillo; De Angelis, Francesco; Vadini, Mirco; Carluccio, Fabio; Vitalone, Laura Merla; D'Amario, Maurizio

    2012-08-01

    To assess the microhardness of three resin composites employed in the adhesive luting of indirect composite restorations and examine the influence of the overlay material and thickness as well as the curing time on polymerization rate. Three commercially available resin composites were selected: Enamel Plus HRI (Micerium) (ENA), Saremco ELS (Saremco Dental) (SAR), Esthet-X HD (Dentsply/DeTrey) (EST-X). Post-polymerized cylinders of 6 different thicknesses were produced and used as overlays: 2 mm, 3 mm, 3.5 mm, 4 mm, 5 mm, and 6 mm. Two-mm-thick disks were produced and employed as underlays. A standardized amount of composite paste was placed between the underlay and the overlay surfaces which were maintained at a fixed distance of 0.5 mm. Light curing of the luting composite layer was performed through the overlays for 40, 80, or 120 s. For each specimen, the composite to be cured, the cured overlay, and the underlay were made out of the same batch of resin composite. All specimens were assigned to three experimental groups on the basis of the resin composite used, and to subgroups on the basis of the overlay thickness and the curing time, resulting in 54 experimental subgroups (n = 5). Forty-five additional specimens, 15 for each material under investigation, were produced and subjected to 40, 80, or 120 s of light curing using a microscope glass as an overlay; they were assigned to 9 control subgroups (n = 5). Three Vicker's hardness (VH) indentations were performed on each specimen. Means and standard deviations were calculated. Data were statistically analyzed using 3-way ANOVA. Within the same material, VH values lower than 55% of control were not considered acceptable. The used material, the overlay thickness, and the curing time significantly influenced VH values. In the ENA group, acceptable hardness values were achieved with 3.5-mm or thinner overlays after 120 or 80 s curing time (VH 41.75 and 39.32, respectively), and with 2-mm overlays after 40 s (VH 54

  5. Evaluation of Vickers hardness of bulk-fill composites cured by different light sources

    Science.gov (United States)

    Bakhsh, Turki A.; Yagmoor, Mohammed A.; Alsadi, Fahad M.; Jamleh, Ahmad

    2016-02-01

    [Objective] The current in vitro study was performed to evaluate Vickers hardness (VHN) of two different composite resins that were cured by using two different light curing units. [Materials and Methods] Porcelain tube samplers were used to fabricate composite cylinders from either Tetric Evoceram BulkFill (BF; Ivoclar/Vivadent, USA) or SonicFill composite (SF; Kerr, USA). Each composite type had 12 cylindrical specimens, and each specimen was cured with either Blue-phase N light-cure (Bp; Polywave, Ivoclar/Vivadent, USA) or Elipar S10 (El; Monowave, 3M ESPE, Germany). The VHN data were analyzed and tested by using Mann-Whitney U test at a significance level of 5%. [Results] Statistical analyses demonstrated an interaction between the type of composite and the type of light curing source. Significant differences (Plight-cure. This research was supported by King Abdulaziz University.

  6. Environmental SEM and dye penetration observation on resin-tooth interface using different light curing method.

    Science.gov (United States)

    Yoshikawa, Takako; Morigami, Makoto; Sadr, Alireza; Tagami, Junji

    2016-01-01

    The aim of this study was the effects of different light curing methods on marginal sealing and resin composite adaptation to the cavity wall using the dye penetration test and environmental scanning electron microscope (SEM) observations. Cylindrical cavities were prepared on cervical regions. The teeth were restored with Clearfil Liner Bond 2 V adhesive and filled with Clearfil Photo Bright or Palfique Estelite resin composites. These resins were cured with a conventional light-curing method or a slow-start curing method. After thermal cycling, the specimens were subjected to the dye penetration test to evaluate marginal sealing and adaptation of the resin composites to the cavity walls. These resin-tooth interfaces were then observed using environmental SEM. The light-cured resin composite, which exhibited increased contrast ratios during polymerization, suggests high compensation for polymerization stress using the slow-start curing method. There was a high correlation between dye penetration test and environmental SEM observation.

  7. THE EFFECT OF DIFFERENT LIGHT-CURING UNITS ON TENSILE STRENGTH AND MICROHARDNESS OF A COMPOSITE RESIN

    Science.gov (United States)

    Franco, Eduardo Batista; dos Santos, Patrícia Aleixo; Mondelli, Rafael Francisco Lia

    2007-01-01

    The aim of this study was to evaluate the influence of different light-curing units on the tensile bond strength and microhardness of a composite resin (Filtek Z250 – 3M/ESPE). Conventional halogen (Curing Light 2500 – 3M/ESPE; CL) and two blue light emitting diode curing units (Ultraled – Dabi/Atlante; UL; Ultrablue IS – DMC; UB3 and UB6) were selected for this study. Different light intensities (670, 130, 300, and 600 mW/cm2, respectively) and different curing times (20s, 40s and 60s) were evaluated. Knoop microhardness test was performed in the area corresponding to the fractured region of the specimen. A total of 12 groups (n=10) were established and the specimens were prepared using a stainless steel mold composed by two similar parts that contained a cone-shaped hole with two diameters (8.0 mm and 5.0 mm) and thickness of 1.0 mm. Next, the specimens were loaded in tensile strength until fracture in a universal testing machine at a crosshead speed of 0.5 mm/min and a 50 kg load cell. For the microhardness test, the same matrix was used to fabricate the specimens (12 groups; n=5). Microhardness was determined on the surfaces that were not exposed to the light source, using a Shimadzu HMV-2 Microhardness Tester at a static load of 50 g for 30 seconds. Data were analyzed statistically by two-way ANOVA and Tukey's test (p<0.05). Regarding the individual performance of the light-curing units, there was similarity in tensile strength with 20-s and 40-s exposure times and higher tensile strength when a 60-s light-activation time was used. Regarding microhardness, the halogen lamp had higher results when compared to the LED units. For all light-curing units, the variation of light-exposure time did not affect composite microhardness. However, lower irradiances needed longer light-activation times to produce similar effect as that obtained with high-irradiance light-curing sources. PMID:19089182

  8. Residual HEMA and TEGDMA Release and Cytotoxicity Evaluation of Resin-Modified Glass Ionomer Cement and Compomers Cured with Different Light Sources

    Directory of Open Access Journals (Sweden)

    Murat Selim Botsali

    2014-01-01

    Full Text Available The purpose of this study was first to evaluate the elution of 2-hydroxyethyl methacrylate (HEMA and triethylene glycol dimethacrylate (TEGDMA monomers from resin-modified glass ionomer cement (RMGIC and compomers cured with halogen and light-emitting diode (LED light-curing units (LCUs. The effect of cured materials on the viability of L929 fibroblast cells was also evaluated. One RMGIC (Ketac N100 and two compomers (Dyract Extra and Twinkystar were tested. Materials were prepared in teflon disks and light-cured with LED or halogen LCUs. The residual monomers of resin materials in solution were identified using high-performance liquid chromatography. The fibroblast cells’ viability was analyzed using MTT assay. The type of LCU did not have a significant effect on the elution of HEMA and TEGDMA. A greater amount of HEMA than TEGMDA was eluted. The amount of TEGDMA eluted from Twinkystar was greater than Dyract Extra (P0.05. Curing with the LED LCU decreased the cells’ viability more than curing with the halogen LCU for compomers. For Ketac N100, the halogen LCU decreased the cells’ viability more than the LED LCU.

  9. Energy savings by implementation of light quality LED lighting. Final report; Implementering af energibesparelser ved benyttelse af hoejkvalitets LED belysning. Slutrapport

    Energy Technology Data Exchange (ETDEWEB)

    Dam-Hansen, C.; Thorseth, A.; Poulsen, Peter

    2010-03-15

    The project developed two new LED light sources and systems, emphasising the potential of LED technology for energy savings and lighting quality. A LED light source for display case lighting, replacing incandescent lamps, was successfully installed in the Treasury at Rosenborg Castle in Copenhagen, Denmark, and it was decided to extend the solution in 2010. Electricity savings of 74% were achieved. LED light sources replacing halogen bulbs in cooker hoods reduce electricity consumption by 69% and ensure even lighting of the entire working surface with about 500 lux at all cooking areas. Furthermore, a new LED optics system was patented. (ln)

  10. Influence of prolonged light-curing time on the shear bonding strength of resin to bleached enamel.

    Science.gov (United States)

    Hussain, Manal; Wang, Yining

    2010-01-01

    This study evaluated the effect of prolonged light-curing time using a light-emitting diode unit (LED) on the shear bond strength of a resin composite to enamel immediately after bleaching. The enamel surfaces of human molars were divided into four groups: one control and three bleaching groups. One bleaching group (CP) was exposed to a 10% carbamide peroxide bleaching agent and bonded after 24 hours. The other two bleaching groups (HP) were bleached with a 38% hydrogen peroxide bleaching agent, then bonded either within one hour (HPA) or after 24 hours (HPB). All groups were subdivided into two subgroups and cured for two different times (20 or 40 seconds) with an LED unit. Shear bond strength (SBS) was tested with a universal-testing machine and the data were analyzed by ANOVA and post-hoc tests. Scanning electron micrographs of representative specimens were taken. A significant difference was seen between the control and HPA groups for both curing times (p = 0.000). However, neither the CP nor HPB groups showed any significant differences compared with the control groups (p > 0.05). Two-way ANOVA showed that a significant effect of the curing time factor was recorded for all groups (p = 0.000). Prolonged curing time, using an LED unit with a light intensity of 500 mW/cm2, increased resin-enamel bonding strengths for the control and bleached groups when bonding was performed after 24 hours of immersion in deionized water. However, the SBS was still compromised when bonding was performed immediately to enamel bleached with 38% HP.

  11. LED lighting for greenhouses. Final report; LED belysning til vaeksthuse. Slutrapport

    Energy Technology Data Exchange (ETDEWEB)

    OEstergaard, J.E. (Syddansk Univ. (SDU). Erhvervsinnovation og Teknologi, Odense (Denmark))

    2011-01-15

    The project had 3 main objectives: 1) To develop a prototype of a LED-based luminaire that can replace the existing glasshouse horticultural lighting. The project have developed a working prototype and experimentally replaced the traditional HPS luminaires in a controlled growing area. The project succeeded in producing plants of comparable quality. However, the project shows that the prototype can be improved by: x) being further integrated into the existing horticultural production technology (eg climate computers and purchase of electricity) x) adapting configuration of luminaires specifically to each plant variety x) adapting different cooling technologies to match specific customer needs x) In some cases being combined with heat input to optimize the overall economy. 2) To achieve an effective electricity savings of 50-80% - equivalent to a value of approx. DKK 5 million for a medium sized nursery. The verified electricity savings was 40%. In test setups and in well defined and controllable production areas the prototypes achieved electricity savings of > 50%. It is expected that a new generation of LEDs (Q3 2010) will allow for greater power savings. 3) To continue prototype development and initiate commercialization of the project through the company Fionia Lighting A/S. The shareholders of the company have allocated capital to the company to allow us to address the main challenges in commercializing the technology. It is expected that the company will enter a strategic alliance with a major industrial player in the beginning of 2011. (Author)

  12. In-vitro bond strengths and clinical failure rates of metal brackets bonded with different light-emitting diode units and curing times.

    Science.gov (United States)

    Oz, Abdullah Alper; Oz, Aslıhan Zeynep; Arici, Selim

    2016-02-01

    The purpose of this study was to compare the clinical failure rates and the in-vitro bond strengths of metal brackets bonded with different light-emitting diode (LED) devices and curing times. Forty patients were included in the clinical part of this study. A split-mouth design was used, with the adhesive in group 1 cured for 10 seconds with an LED unit (Elipar S10; 3M Unitek, Monrovia, Calif), and the adhesive in group 2 cured for 3 seconds with another LED unit (VALO Ortho; Ultradent Products, South Jordan, Utah). Bond failures during 12 months of orthodontic treatment were recorded. In-vitro performance of the brackets was also compared by bonding brackets to extracted premolars and using the same light units and curing times (n = 20 for each group). The adhesive remnant index was used to determine the bond failure interface. Clinical bond failure rates were 2.90% for the Elipar and 3.16% for the VALO curing units. The difference in bracket failure rates between the 2 LED devices was not statistically significant. No statistically significant difference was found between the in-vitro bond strengths of the groups. Our findings regarding long-term clinical survival rates and in-vitro bond strengths indicate that bracket bonding can be safely accomplished in 10 seconds of light-curing with an Elipar LED and 3 seconds of light-curing with a VALO LED. Copyright © 2016 American Association of Orthodontists. Published by Elsevier Inc. All rights reserved.

  13. [Improvement of light-cured indirect inlays durability by means of electromagnetic field].

    Science.gov (United States)

    Nidzel'skiĭ, M Ia; Korotetskaia-Zinkevich, V L

    2014-01-01

    The main strength characteristics of light-cured resins used for replacement of dental hard tissues defects are destructive stress by compression, microhardness, resistance to abrasion, impact and water absorption. The study focuses on some strength features of composite materials for inlays processed by electromagnetic field. Four sample series of light cured resin (Charisma, Heraus Kulzer, Germany) were used to assess strength features changes in various curing methods: 10 control samples were polymerized by conventional light-curing device, while 30 were additionally processed by electromagnetic field of various intensity (60, 80 and 100 Oe, 10 samples for each group). The obtained results confirm the positive effects of electromagnetic field on strength features of light-cured resins which improves the quality of inlays.

  14. Effect of light-emitting diode and halogen light curing on the micro-hardness of dental composite and resin-modified glass ionomer cement: an in vitro study.

    Science.gov (United States)

    Bhalla, M; Patel, D; Shashikiran, N D; Mallikarjuna, R M; Nalawade, T M; Reddy, H K

    2012-01-01

    This in vitro study was conducted to evaluate and compare the micro-hardness of composite resin and resin-modified glass ionomer cement using light-emitting diode (LED) and halogen curing and also to inter-compare the effect of LED and halogen curing. The study sample comprised of 4 stainless steel plates with a thickness of 2 mm. For these stainless steel plates, holes were made to a diameter of 3 mm. The samples were divided into 4 groups of 8 each and labeled as group I, group II, group III, group IV, thus making provision for the two different modes of light exposure. In each group, the hole was restored with its respective restorative material and cured with light-curing unit according to manufacturer instructions. The results were statistically analyzed using Mann-Whitney test. It was concluded that the curing efficacy of the LED lamp was comparable to that of conventional halogen lamp, even with a 50% reduction in cure time, and resin composite (Filtek Z-250) presented the highest hardness values, whereas complete hardening of resin-modified glass ionomer cement (RMGIC) (Vitremer) was observed because of its self-curing system even after the removal of light source.

  15. Effect of light-emitting diode and halogen light curing on the micro-hardness of dental composite and resin-modified glass ionomer cement: An in vitro study

    Directory of Open Access Journals (Sweden)

    M Bhalla

    2012-01-01

    Full Text Available Aims : This in vitro study was conducted to evaluate and compare the micro-hardness of composite resin and resin-modified glass ionomer cement using light-emitting diode (LED and halogen curing and also to inter-compare the effect of LED and halogen curing. Materials and Methods : The study sample comprised of 4 stainless steel plates with a thickness of 2 mm. For these stainless steel plates, holes were made to a diameter of 3 mm. The samples were divided into 4 groups of 8 each and labeled as group I, group II, group III, group IV, thus making provision for the two different modes of light exposure. In each group, the hole was restored with its respective restorative material and cured with light-curing unit according to manufacturer instructions. The results were statistically analyzed using Mann-Whitney test. Results and conclusion: It was concluded that the curing efficacy of the LED lamp was comparable to that of conventional halogen lamp, even with a 50% reduction in cure time, and resin composite (Filtek Z-250 presented the highest hardness values, whereas complete hardening of resin-modified glass ionomer cement (RMGIC (Vitremer was observed because of its self-curing system even after the removal of light source.

  16. Quantification of the amount of light passing through zirconia: the effect of material shade, thickness, and curing conditions.

    Science.gov (United States)

    Ilie, Nicoleta; Stawarczyk, Bogna

    2014-06-01

    This study aimed to evaluate the amount of light (360-540 nm) passing through shaded zirconia with respect to material thickness, exposure distance, and different curing modes. The specimens were divided into groups according to thickness as follows: 0.5, 1, 1.5, 2, 2.5, and 3 mm. Thirty-five zirconia and seven glass-ceramic (control group) specimens were fabricated for each group (N=252). Zirconia was divided into five subgroups (n=7) and stained to the following shades: CL1, CL2, CL3, and CL4. One zirconia group remained unstained (CL0). Irradiance passing through the different specimens was measured using a violet-blue LED curing unit in three curing modes (Xtra-power, high-power, and standard-power mode) with a fibre-optic USB4000 spectrometer. Irradiance was measured at varying exposure distances, ranging from direct contact of the curing unit with the surface to a distance of 7 mm from the surface, increasing in 1 mm steps. Data were analyzed using a multivariate analysis and linear mixed models (plight passing through ceramics is an important aspect for an adhesive cementation, since many dual-cured luting materials reveal a high sensitivity to additional occurrence of blue light. For restorations thicker than 1.5 mm in light-shaded zirconia and 0.5 mm in darker-shaded zirconia the use of less-light-sensitive dual-cured cements are recommended. Copyright © 2014 Elsevier Ltd. All rights reserved.

  17. Light-Emitting Diode (LED) Traps Improve the Light-Trapping of Anopheline Mosquitoes.

    Science.gov (United States)

    Costa-Neta, B M; da Silva, A A; Brito, J M; Moraes, J L P; Rebêlo, J M M; Silva, F S

    2017-11-07

    Numerous advantages over the standard incandescent lamp favor the use of light-emitting diodes (LEDs) as an alternative and inexpensive light source for sampling medically important insects in surveillance studies. Previously published studies examined the response of mosquitoes to different wavelengths, but data on anopheline mosquito LED attraction are limited. Center for Disease Control and Prevention-type light traps were modified by replacing the standard incandescent lamp with 5-mm LEDs, one emitting at 520 nm (green) and the other at 470 nm (blue). To test the influence of moon luminosity on LED catches, the experiments were conducted during the four lunar phases during each month of the study period. A total of 1,845 specimens representing eight anopheline species were collected. Anopheles (Nyssorhynchus) evansae (35.2%) was the most frequently collected, followed by An. (Nys.) triannulatus (21.9%), An. (Nys.) goeldii (12.9%), and An. (Nys.) argyritarsis (11.5%). The green LED was the most attractive light source, accounting for 43.3% of the individuals collected, followed by the blue (31.8%) and control (24.9%) lights. The LED traps were significantly more attractive than the control, independent of the lunar phase. Light trapping of anopheline mosquitoes was more efficient when the standard incandescent lamp was replaced with LEDs, regardless of the moon phase. The efficiency of LEDs improves light trapping results, and it is suggested that the use of LEDs as an attractant for anopheline mosquitoes should be taken into consideration when sampling anopheline mosquitoes. © The Authors 2017. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  18. Light emitting diode (LED) use in artificial lighting for broiler chicken production

    OpenAIRE

    Santana,Mayara R. de; Garcia,Rodrigo G.; Naas,Irenilza de A.; Paz,Ibiara C. de L. A.; Caldara,Fabiana R.; Barreto,Bruna

    2014-01-01

    Light emitting diode (LED) has been used in commercial poultry industry by presenting superior energy savings and providing feasibility on production process. The objective of this research was to evaluate performance and carcass yield of broiler chickens exposed to different LED colors compared with fluorescent lamps. For that, two experiments (E1 and E2) were performed and 2,646 Cobb® chickens were used. In experiment E1, male birds were exposed to 20 lux artificial lighting with red, yello...

  19. Effect of light-curing units on push-out fiber post bond strength in root canal dentin

    Science.gov (United States)

    Calixto, L. R.; Bandéca, M. C.; Silva, F. B.; Rastelli, A. N. S.; Porto-Neto, S. T.; Andrade, M. F.

    2009-08-01

    The purpose of this study was to evaluate the effectiveness of different light-curing units on the bond strength (push-out) of glass fiber posts in the different thirds of the root (cervical, middle and apical) with different adhesive luting resin systems (dual-cure total-etch; dual-cured and self-etch bonding system; and dual-cure self-adhesive cements), Disks of the samples ( n = 144) were used, with approximately 1 mm of thickness of 48 bovine roots restored with glass fiber posts, that were luted with resin cements photo-activated by halogen LCU (QTH, Optilux 501) and blue LED (Ultraled), with power densities of 600 and 550 mW/cm2, respectively. A universal testing machine (MTS 810 Material Test System) was used with a 1 mm diameter steel rod at cross-head speed of 0.5 mm/min until post extrusion, with load cell of 50 kg, for evaluation of the push-out strength in the different thirds of each sample. The push-out strength values in kgf were converted to MPa and analyzed through Analysis of Variance and Tukey’s test, at significance level of 5%. The results showed that there were no statistical differences between the QTH and LED LCUs. The self-adhesive resin cement had lower values of retention. The total-etch and self-adhesive system resin cements seem to be a possible alternative for glass fiber posts cementation into the radicular canal and the LED LCU can be applied as an alternative to halogen light on photo-activation of dual-cured resin cements.

  20. Surface and pulpal temperature comparison of tooth whitening using lasers and curing lights

    Science.gov (United States)

    White, Joel M.; Pelino, Jose; Rodrigues, Rively; Zwhalen, Brian J.; Nguyen, Max H.; Wu, Emily

    2000-03-01

    Chemical action of bleaching agents applied to tooth surface is accelerated by increase in temperature. This in vitro study measured the temperature rises on the surface and in the pulp of teeth during whitening using a diode laser, a plasma arc curing (PAC) light and conventional curing lights. Extracted, non-carious single-rooted teeth were exposed to PAC light and laser at times ranging from 10 to 60 seconds and energy ranges of 2 W, 4 W, and 6 W, and to low-intensity curing lights from 1 to 4 minutes. Maximum temperature rises were analyzed for both pulpal and surface temperature. Diode laser exposures at 2 W for all times and at 4 watts for 10 seconds and PAC light exposures at 10 seconds all produced acceptably safe pulpal rises equivalent to conventional light-curing exposures. Exposures at these settings also attained surface temperature rises that were significantly higher than those using conventional light-curing. The diode laser demonstrated bleaching results equivalent to the PAC light, and both were achieved in significantly less times than conventional light- curing.

  1. The influence of light exposure on polymerization of dual-cure resin cements.

    Science.gov (United States)

    Rueggeberg, F A; Caughman, W F

    1993-01-01

    This study investigated the degree of monomer conversion of four commercial dual-cure resin cements. The products were subjected to various postmix treatments: no light exposure, a 60-second exposure through Mylar only, and either a 20-second or 60-second exposure through an overlying cured wafer of composite 1.5 mm thick. The infrared spectrum of the treated specimens was recorded at specified times postmix for each cure treatment: 2, 5, 10, 30, and 60 minutes as well as after 24 hours. The degree of cure was then determined from the infrared spectra. The results demonstrate a wide range of potential cures among the various brands. Regardless of brand, the chemical component of cure was always lower than when the specimens were exposed to any lighting condition. For most resin systems tested, the cure observed 10 minutes postmix was almost equivalent to the cure after 24 hours. Despite manufacturers' claims, there is no evidence for a substantial chemically induced polymerization of dual-cure resins that occurs after light exposure is completed.

  2. Cost and energy-efficient (LED, induction and plasma) roadway lighting.

    Science.gov (United States)

    2013-11-01

    There is an increasing interest in using new lighting technologies such as light emitting diode (LED), Induction, and Plasma light sources : in roadway lighting. The most commonly claimed benefits of the new lighting systems include increased reliabi...

  3. Correlation between the beam profile from a curing light and the microhardness of four resins.

    Science.gov (United States)

    Price, Richard B T; Labrie, Daniel; Rueggeberg, Frederick A; Sullivan, Braden; Kostylev, Ivan; Fahey, John

    2014-12-01

    To demonstrate the effect of localized irradiance and spectral distribution inhomogeneities of one LED-based dental light-curing unit (LCU) on the corresponding microhardness values at the top, and bottom surfaces of four dental resin-based composites (RBCs), which contained either camphorquinone (CQ) alone or a combination of CQ and monoacylphosphine oxide (TPO) as photoinitiators. Localized irradiance beam profiles from a polywave LED-based LCU were recorded five times using a laser beam analyzer, without and with either a 400 nm or 460 nm narrow bandpass filter placed in front of the camera lens. Five specimens of each of the four RBCs (two containing CQ/TPO and two containing CQ-only) were exposed for 5-, 10-, or 30-s with the light guide directly on the top surface of the RBC. After 24 h, Knoop microhardness values were measured at 45 locations across the top and bottom surfaces of each specimen. Microhardness readings for each RBC surface and exposure time were correlated with localized patterns of the LCU beam profile, measured using the 400 nm and 460 nm bandpass filters. Spearman rank correlation was used to avoid relying on an assumption of a bivariate normal distribution for the KHN and irradiance. The local irradiance and spectral emission values were not uniformly distributed across the light tip. There was a strong significant positive correlation with the irradiance beam profile values from the LCU taken through bandpass filters and the microhardness maps of the RBC surfaces exposed for 5 and 10 s. The strength of this correlation decreased with increasing exposure time for the RBCs containing CQ only, and increased for the RBCs containing both CQ and TPO. Localized beam and spectral distributions across the tip end of the light guide strongly correlated with corresponding areas of microhardness in both the top and bottom surfaces among four RBCs with different photoinitiator contents. Significance: A light-curing unit with a highly inhomogeneous

  4. Heat-cured Acrylic Resin versus Light-activated Resin: A Patient ...

    African Journals Online (AJOL)

    Context: Although light-activated resins (Eclipse) have been reported to possess superior physical and mechanical properties compared with the heat-cured acrylic resins (Lucitone-199), a few studies have compared overdentures with a locator attachment constructed from heat-cured acrylic resins with those constructed ...

  5. Risks of age related macular degeneration and led lighting

    Directory of Open Access Journals (Sweden)

    V.A. Kaptsov

    2017-12-01

    Full Text Available Spectral structure of environmental light can have significant influence on risks of various eye diseases which can evolve quite early. The paper dwells on how age-related macular degeneration evolves and on a part which eye age pigment plays in the process. We discuss predictive models for age pigment accumulation and methodology of their creation. We created a predictive mathematical model for accumulated A2E age pigment quantity allowing for LED lighting peculiarities and its age-related perception. The model encompasses active oxygen forms generation evolving due to decrease in antioxidant cellular protection efficiency in a lighting environment with a higher blue light dose. It is shown that superoxide dismutase, catalase and glutathione peroxidase 1 (GRX 1 efficiency within 445 (plus minus 10 nanometers range drops substantially in blue light; it increases risks of lower cellular resistance to effects exerted by non-compensated active oxygen forms. These processes which are rather long-term can lead to early age-related macular degeneration. Mathematical calculations prove that in the nearest future a share of patients aged 30–40 who suffer from age-related macular degeneration will grow drastically; it will eventually lead to an increased number of disabled people aged 50–60 whose disability is caused by eyesight disorders. It is shown that if we fail to discover any mechanisms aimed at lowering risks of early age-related macular degeneration evolvement in the nearest future, total costs required for solving eyesight disorders issue will grow substantially. Thus, in 2012 about 140 billion dollars were spent on the eyesight disorders issue all over the world; the sum is likely to reach 377 billion dollars in 2050.

  6. Stolephorus sp Behavior in Different LED (Light Emitting Diode) Color and Light Intensities

    Science.gov (United States)

    Fitri Aristi, D. P.; Ramadanita, I. A.; Hapsari, T. D.; Susanto, A.

    2018-02-01

    This research aims to observe anchovy (Stolephorus sp) behavior under different LED light intensities that affect eye physiology (cell cone structure). The materials used were Stolephorus sp taken from the waters off Jepara and 13 and 10 watt light emitting diode (LED). The research method was an experiment conducted from March through August 2015 in the waters off Jepara. Data analysis of visual histology and fish respond was carried out at the fishing gear material laboratory, anatomy and cultivate. Cone cell structure (mosaic cone) of Stolephorus sp forms a connected regular square pattern with every single cone surrounded by four double cones, which indicate that anchovies are sensitive to light. The 13 watt LED (628 lux) has faster response than the 10 watt LED (531 lux) as it has wider and higher emitting intensity, which also attracts fish to gather quicker.

  7. Patterns of Light Chasing the Spectrum from Aristotle to LEDs

    CERN Document Server

    Beeson, Steven

    2008-01-01

    Light is all around us – even when we do not see it. Our eyes do not detect the higher energy and shorter-than-visible-wavelength ultraviolet radiation, yet we know it is there from the sunburn we receive in Arizona. We know that window glass can block ultraviolet rays so we do not get a burn while driving with the windows rolled up. Our eyes do not detect the low-energy, long-wavelength infrared (IR) radiation but we know it exists from discussions of war applications and televised images of guided weapons targets. We also know about radio waves from the little boxes that talk to us and x-rays from the dentist's office. Patterns of Light, Chasing the Spectrum from Aristotle to LEDs, written by Steve Beeson and Jim Mayer starts with the visible – the straight path of light. It continues with chapters detailing reflection (mirrors, storefront windows) and refraction (eyeglasses, binoculars). Color is then introduced with the query "Why is the sky blue?" After answering that and other similar questions ("Wh...

  8. Retinal endoilluminator toxicity of xenon and light-emitting diode (LED) light source: rabbit model.

    Science.gov (United States)

    Aydin, Bahri; Dinç, Erdem; Yilmaz, S Necat; Altiparmak, U Emrah; Yülek, Fatma; Ertekin, Sevda; Yilmaz, Mustafa; Yakın, Mehmet

    2014-09-01

    This study evaluates retinal toxicity due to endoillumination with the light-emitting diode (LED) light source in comparison to endoillumination with xenon light source. Twenty-five eyes of 14 New Zealand pigmented rabbits were used in the study. The LED light (Omesis Medical Systems, Turkey) group was composed of 7 right eyes, while the other 7 right eyes constituted the xenon group (420 nm filter, 357mW/cm(2)) (Bright Star; DORC, Zuidland, Netherlands). Eleven untreated left eyes composed the control group. Twenty gauge pars plana incision 1.5 mm behind the limbus was performed in the right eyes. Twenty gauge bullet type fiberoptic endoilluminator was inserted into the eye from the incision without any pars plana vitrectomy. Fiberoptic endoilluminator was placed in such a way that it was directed toward visual streak of the rabbit retina with a 5 mm distance to retinal surface. Endoillumination was then applied for 20 min with a maximum light intensity for LED and xenon light. In left control eyes, no surgical procedure and no endoillumination were performed. One week after the endoillumination procedure, both eyes of the rabbits were enucleated following electroretinography. Sections stained with hematoxylin and eosin to evaluate morphologic changes. Retina tissues were assessed by active caspase-3 staining. There was no difference in the shape of the waveforms recorded in the eyes endoilluminated with LED light and xenon light sources compared to control eyes both before and after endoillumination application (p > 0.05). Microscopic evaluation of the retinas with hematoxylin and eosin staining demonstrated that all study groups have normal histologic properties similar to control group. No apoptosis positive cells were found within all sections in all groups. When the LED light source is used with maximum power and limited duration for endoillumination in rabbit eyes it does not produce phototoxic effects that may be detectable by electrophysiology

  9. Temperature changes caused by light curing of fiber-reinforced composite resins

    Science.gov (United States)

    Ilday, Nurcan Ozakar; Sagsoz, Omer; Karatas, Ozcan; Bayindir, Yusuf Ziya; Çelik, Neslihan

    2015-01-01

    Objective: The aim of the study is to evaluate temperature change in fiber-reinforced composite (FRC) resin photopolymerized with a light-emitting diode (LED) light-curing unit (LCU). Materials and Methods: Forty dentine disks (1 mm thick and 8 mm diameter) were prepared from human molars. The FRC specimens (2 mm thickness and 8 mm diameter) consisted of polyethylene fiber (Construct (CT)) products or glass fiber (ever Stick (ES)) and one hybrid composite bonded to the dentin disks and polymerized with an LED LCU. Control groups were prepared using the hybrid composite. Temperature rise in dentine samples under the FRC bonded disks was measured using a K-type thermocouple, and data were recorded. Temperature change data were subjected to analysis of variance (ANOVA) and Duncan's test. Results: The results show that addition of fiber (one or two layers) did not change temperature rise values at any of the exposure times (P > 0.05). The CT fiber/two layer/40 s group exhibited the greatest temperature rise (5.49 ± 0.62) and the ES/one layer/10 s group the lowest rise (1.75 ± 0.32). A significant difference was observed in temperature rise measured during 10 and 20 s exposures (P < 0.05). Conclusion: Maximal temperature rise determined in all groups was not critical for pulpal health, although clinicians need to note temperature rises during polymerization. PMID:26069409

  10. Novel thin-GaN LED structure adopted micro abraded surface to compare with conventional vertical LEDs in ultraviolet light

    Science.gov (United States)

    Chiang, Yen Chih; Lin, Chien Chung; Kuo, Hao Chung

    2015-04-01

    In this study, novel thin-GaN-based ultraviolet light-emitting diodes (NTG-LEDs) were fabricated using wafer bonding, laser lift-off, dry etching, textured surface, and interconnection techniques. Placing PN electrodes on the same side minimized the absorption caused by electrodes in conventional vertical injection light-emitting diodes (V-LEDs) and the current spreading was improved. The light output power (700 mA) of the NTG-LEDs was enhanced by 18.3% compared with that of the V-LEDs, and the external quantum efficiency (EQE) of the NTG-LEDs was also relatively enhanced by 20.0% compared with that of a reference device. When the current operations were 1,500 mA, the enhancements of the light output power and EQE were 27.4% and 27.2%, respectively. Additionally, the efficiency droop was improved by more than 15% at the same current level.

  11. Effect of different photo-initiators and light curing units on degree of conversion of composites

    Directory of Open Access Journals (Sweden)

    William Cunha Brandt

    2010-09-01

    Full Text Available The aim of this study was to evaluate: (i the absorption of photo-initiators and emission spectra of light curing units (LCUs; and (ii the degree of conversion (DC of experimental composites formulated with different photo-initiators when activated by different LCUs. Blends of BisGMA, UDMA, BisEMA and TEGDMA with camphorquinone (CQ and/ or 1-phenyl-1,2-propanedione (PPD were prepared. Dimethylaminoethyl methacrylate (DMAEMA was used as co-initiator. Each mixture was loaded with 65 wt% of silanated filler particles. One quartz-tungsten-halogen - QTH (XL 2500, 3M/ESPE and two lightemitting diode (LED LCUs (UltraBlue IS, DMC and UltraLume LED 5, Ultradent were used for activation procedures. Irradiance (mW/cm² was calculated by the ratio of the output power by the area of the tip, and spectral distribution with a spectrometer (USB 2000. The absorption curve of each photo-initiator was determined using a spectrophotometer (Varian Cary 5G. DC was assessed by Fourier transformed infrared spectroscopy. Data were submitted to two-way ANOVA and Tukey's test (5%. No significant difference was found for DC values when using LED LCUs regardless of the photo-initiator type. However, PPD showed significantly lower DC values than composites with CQ when irradiated with QTH. PPD produced DC values similar to those of CQ, but it was dependent on the LCU type.

  12. Fiber Optic Systems for Light Curing Rigidization of Inflatable Structures, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — Light (UV and visible) curing composite matrix resins are being explored as an attractive means for rigidizing inflatable spacecraft for large space-deployed...

  13. Integrated Automotive High-Power LED-Lighting Systems in 3D-MID Technology

    NARCIS (Netherlands)

    Thomas, W.

    2014-01-01

    The growing energy consumption of lighting as well as rising luminous efficacies and -fluxes of high-power Light Emitting Diodes (LEDs) have contributed to the widespread use of LEDs in modern lighting systems. One of the most prominent users of the LED-technology is automotive (exterior) lighting.

  14. Visible light communication based vehicle positioning using LED street light and rolling shutter CMOS sensors

    Science.gov (United States)

    Do, Trong Hop; Yoo, Myungsik

    2018-01-01

    This paper proposes a vehicle positioning system using LED street lights and two rolling shutter CMOS sensor cameras. In this system, identification codes for the LED street lights are transmitted to camera-equipped vehicles through a visible light communication (VLC) channel. Given that the camera parameters are known, the positions of the vehicles are determined based on the geometric relationship between the coordinates of the LEDs in the images and their real world coordinates, which are obtained through the LED identification codes. The main contributions of the paper are twofold. First, the collinear arrangement of the LED street lights makes traditional camera-based positioning algorithms fail to determine the position of the vehicles. In this paper, an algorithm is proposed to fuse data received from the two cameras attached to the vehicles in order to solve the collinearity problem of the LEDs. Second, the rolling shutter mechanism of the CMOS sensors combined with the movement of the vehicles creates image artifacts that may severely degrade the positioning accuracy. This paper also proposes a method to compensate for the rolling shutter artifact, and a high positioning accuracy can be achieved even when the vehicle is moving at high speeds. The performance of the proposed positioning system corresponding to different system parameters is examined by conducting Matlab simulations. Small-scale experiments are also conducted to study the performance of the proposed algorithm in real applications.

  15. Emission Characteristics and Effect of Battery Drain in "Budget" Curing Lights.

    Science.gov (United States)

    AlShaafi, M M; Harlow, J E; Price, H L; Rueggeberg, F A; Labrie, D; AlQahtani, M Q; Price, R B

    2016-01-01

    Recently, "budget" dental light-emitting diode (LED)-based light-curing units (LCUs) have become available over the Internet. These LCUs claim equal features and performance compared to LCUs from major manufacturers, but at a lower cost. This study examined radiant power, spectral emission, beam irradiance profiles, effective emission ratios, and the ability of LCUs to provide sustained output values during the lifetime of a single, fully charged battery. Three examples of each budget LCU were purchased over the Internet (KY-L029A and KY-L036A, Foshan Keyuan Medical Equipment Co, and the Woodpecker LED.B, Guilin Woodpecker Medical Instrument Co). Major dental manufacturers provided three models: Elipar S10 and Paradigm (3M ESPE) and the Bluephase G2 (Ivoclar Vivadent). Radiant power emissions were measured using a laboratory-grade thermopile system, and the spectral emission was captured using a spectroradiometer system. Irradiance profiles at the tip end were measured using a modified laser beam profiler, and the proportion of optical tip area that delivered in excess of 400 mW/cm(2) (termed the effective emission ratio) was displayed using calibrated beam profile images. Emitted power was monitored over sequential exposures from each LCU starting at a fully charged battery state. The results indicated that there was less than a 100-mW/cm(2) difference between manufacturer-stated average tip end irradiance and the measured output. All the budget lights had smaller optical tip areas, and two demonstrated lower effective emission ratios than did the units from the major manufacturers. The budget lights showed discontinuous values of irradiance over their tip ends. One unit delivered extremely high output levels near the center of the light tip. Two of the budget lights were unable to maintain sustained and stable light output as the battery charge decreased with use, whereas those lights from the major manufacturers all provided a sustained light output for at least

  16. Light source comprising a common substrate, a first led device and a second led device

    Science.gov (United States)

    Choong, Vi-En

    2010-02-23

    At least one stacked organic or polymeric light emitting diode (PLEDs) devices to comprise a light source is disclosed. At least one of the PLEDs includes a patterned cathode which has regions which transmit light. The patterned cathodes enable light emission from the PLEDs to combine together. The light source may be top or bottom emitting or both.

  17. Do light cured ART conventional high-viscosity glass-ionomer sealants perform better than resin-composite sealants: a 4-year randomized clinical trial

    NARCIS (Netherlands)

    Zhang, W.; Chen, X.; Fan, M.W.; Mulder, J.; Huysmans, M.C.D.N.J.M.; Frencken, J.E.F.M.

    2014-01-01

    OBJECTIVE: The hypotheses tested were: the cumulative survival rates of dentin caries lesion-free pits and fissures of ART conventional high-viscosity glass-ionomer sealants with light-curing (high-intensity LED) and glass-carbomer sealants are higher than those of conventional ART sealants and

  18. Shear bond strength of metallic brackets photo-activated with light-emitting diode (LED at different exposure times

    Directory of Open Access Journals (Sweden)

    Emanuel Braga Rêgo

    2007-10-01

    Full Text Available The purpose of this study was to compare the shear bond strength of orthodontic metallic brackets photo-activated with two different light-curing sources at different exposure times: halogen light (XL 1500, 3M ESPE and LED light (Ortholux, 3M Unitek. Sixty bovine permanent lower incisors were inserted into PVC tubes containing plaster. The buccal surfaces were cleaned with pumice and water, and then etched with 37% phosphoric acid gel. The XT Primer bonding agent (3M Unitek was applied to the enamel surfaces and the metallic pre-coated brackets (Transbond APC II system, 3M Unitek were attached to upper central incisors. The teeth were randomly divided into four groups (n=15. In Group I (Control, halogen light was used for 40 seconds, while in Groups II, III, and IV were light-cured with LED light unit for 40, 10, and 5 seconds, respectively. The teeth were stored in distilled water at 37°C for 24 hours. The brackets were submitted to shear bond strength test in universal testing machine (Instron at a crosshead speed of 0.5 mm/minute. Shear bond strength means (MPa were 4.87 for Group I; 5.89 for Group II; 4.83 for Group III, and 4.39 for Group IV. Tukey's test detected no statistically significant differences among the groups regarding the shear bond strength (p>0.05. Neither of the types of light-curing sources or exposure times influenced the shear bond strength of metallic brackets.

  19. Influence of Emission Spectrum and Irradiance on Light Curing of Resin-Based Composites.

    Science.gov (United States)

    Shimokawa, Cak; Sullivan, B; Turbino, M L; Soares, C J; Price, R B

    This study examined the influence of different emission spectra (single-peak and broad-spectrum) light-curing units (LCUs) delivering the same radiant exposures at irradiance values of 1200 or 3600 mW/cm 2 on the polymerization and light transmission of four resin-based composites (RBCs). Two prototype LCUs that used the same light tip, but were either a single-peak blue or a broad-spectrum LED, were used to deliver the same radiant exposures to the top surfaces of the RBCs using either standard (1200 mW/cm 2 ) or high irradiance (3600 mW/cm 2 ) settings. The emission spectrum and radiant power from the LCUs were measured with a laboratory-grade integrating sphere coupled to a spectrometer, and the light beam was assessed with a beam profiler camera. Four RBCs (Filtek Supreme Ultra A2, Tetric EvoCeram A2, Tetric EvoCeram T, and TPH Spectra High Viscosity A2) were photoactivated using four different light conditions: single-peak blue/standard irradiance, single-peak blue/high irradiance, broad-spectrum/standard irradiance, and broad-spectrum/high irradiance. The degree of conversion (N=5) and microhardness at the top and bottom of 2.3-mm-diameter by 2.5-mm-thick specimens (N=5) were analyzed with analysis of variance and Tukey tests. The real-time light transmission through the RBCs was also measured. For all light conditions, the 2.3-mm-diameter specimens received a homogeneous irradiance and spectral distribution. Although similar radiant exposures were delivered to the top surfaces of the RBCs, the amount of light energy emitted from the bottom surfaces was different among the four RBCs, and was also greater for the single-peak lights. Very little violet light (wavelengths below 420 nm) reached the bottom of the 2.5-mm-thick specimens. The degree of conversion and microhardness results varied according to the RBC (pspectrum lights, while at the bottom, where little violet light was observed, the results were equal or higher when they were photoactivated with

  20. Effect of Shade and Light Curing Mode on the Degree of Conversion of Silorane-Based and Methacrylate-Based Resin Composites.

    Science.gov (United States)

    Sm, Mousavinasab; M, Atai; N, Salehi; A, Salehi

    2016-12-01

    The degree of conversion depends on the material composition, light source properties, distance from light source, light intensity, curing time, and other factors such as shade and translucency. In the present study, we evaluated the effects of different light-curing modes and shades of methacrylate and silorane-based resin composites on the degree of conversion of resin composites (DC). The methacrylate-based (Filtek Z250, 3M, ESPE) and low-shrinkage silorane-based (Filtek P90, 3M, ESPE) resin composites were used in three groups as follows: group 1-Filtek Z250 (shade A3), group 2-Filtek Z250 (shade B2), and group 3-Filtek P90 (shade A3). We used a light-emitting diode (LED) curing unit for photopolymerization. 10 samples were prepared in each group to evaluate the degree of conversion; 5 samples were cured using soft-start curing mode, and the other 5 were cured using standard curing mode. The DC of the resin composites was measured using Fourier Transform Infrared Spectroscopy (FTIR). The data were analyzed using Kruskal Wallis and one-way ANOVA statistical tests. The degree of conversion of silorane-based resin composite was 70 - 75.8% and that of methacrylate-based resin composites was 60.2 - 68.2% (p = 0.009). The degree of conversion of the composite with brighter colour (B2) was statistically more than the darker composite (A3). Higher degree of conversion was achieved applying the standard curing mode. The results of the study showed that the colour and type of the resin composite and also the curing mode influence the degree of conversion of resin composites.

  1. Comparative evaluation of sealing ability of light cure glass ionomer cement and light cure composite as coronal sealing material: An in vitro study

    Directory of Open Access Journals (Sweden)

    Pragya Jaiswal

    2017-01-01

    Full Text Available Aim: To compare and evaluate the sealing ability of light cure composite and light cure GIC as coronal sealing materials. Materials and Methods: 30 extracted human teeth were divided into three experimental groups of 10 teeth each. The teeth in group I are obturated without coronal seal, teeth in group II are obturated with light cure GIC (3M ESPE VITREMER as coronal seal and teeth in group III are obturated with light cure composite(3M ESPE filtek z250 as coronal seal, after removing 2mm of coronal gutta percha. These teeth (crown portion are then suspended in methylene blue, sealed and kept for 72 hours, to observe the amount of dye penetration. After 72 hours teeth were removed, washed under running water, dried and sectioned longitudinally, separating buccal and lingual halves. The linear extent of dye penetration was measured from cavosurface margin of the access cavity to the most apical extent of dye penetration point. The length from the cavosurface margin to the apex of the tooth was also measured and percentage linear micro leakage was estimated. Statistical Analysis: Data was statistically analyzed using one-way ANOVA followed by Post-Hoc Multiple comparison (Bonferroni. Results: In the present study specimens in group I showed the maximum percentage of linear microleakage of 31.51 percent. The specimens in group II showed the minimal amount of linear micro leakage of 6.49 percent. Conclusion: It can be concluded coronal seal reduces the micro leakage, and light cure GIC has better coronal sealing ability.

  2. Demonstration Assessment of Light-Emitting Diode (LED) Roadway Lighting, I-35W Bridge, Minneapolis, Minnesota, Phase II Report

    Energy Technology Data Exchange (ETDEWEB)

    Kinzey, B. R. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Davis, R. G. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2014-09-30

    On the I-35W Bridge in Minneapolis, Minnesota, the GATEWAY program conducted a two-phase demonstration of LED roadway lighting on the main span, which is one of the country's oldest continuously operated exterior LED lighting installations. The Phase II report documents longer-term performance of the LED lighting system that was installed in 2008, and is the first report on the longer-term performance of LED lighting in the field.

  3. Comparison between two methods to evaluate temperature changes produced by composite light curing units and polymerization techniques.

    Science.gov (United States)

    Loureiro, F H F; Consani, S; Guiraldo, R D; Consani, R L X; Berger, S B; Carvalho, R V; Correr-Sobrinho, L; Sinhoreti, M A C

    2011-10-01

    This study evaluated the temperature change into the pulp chamber during the light curing of composite resin by direct (bovine tooth) and indirect (matrix) methods. Direct method: fifty standardized cavities (2x2x2 mm) were prepared in bovine incisors, which were randomly assigned to evaluation of the temperature changes in the pulp chamber. Indirect method: temperature changes were evaluated through a dentine slice of 1.0 mm thickness in a elastomer cubic mold (2x2x2 mm). Filtek Z250 composite resin (3M/ESPE) was photo-activated using three light curing units: quartz-tungsten-halogen (QTH) by continuous, soft-start or intermittent light modulations; light emitting diode (LED); and plasma arc-curing (PAC). Ten groups (N.=10) were established according to technique evaluation and photo-activation methods. All experiments were carried out in a controlled environment (37 °C and 50 ± 10% relative humidity). The temperature changes were recorded using a digital thermometer attached to a type-K thermocouple in contact with the dentin slice (indirect method) or in contact with the axial wall (dentin) of pulp chamber (direct method). The results were submitted to ANOVA and Tukey's test (α=0.05). Temperature changes were statistically higher for the matrix indirect method (2.56 ºC) than bovine teeth direct method (1.17ºC). The change temperature was statistically higher for the PAC (1.77 ºC) when compared to other photo-activation modes in bovine teeth direct method. The two methods of temperature evaluation were different, however indirect method detected the higher temperature increase. Higher energy density arising from the light curing units and polymerization techniques promoted higher temperature increase.

  4. High power light emitting diode (LED) arrays versus halogen light polymerization of oral biomaterials: Barcol hardness, compressive strength and radiometric properties.

    Science.gov (United States)

    Mills, Robin W; Uhl, Alexander; Blackwell, Gordon B; Jandt, Klaus D

    2002-07-01

    The clinical performance of light polymerized dental composites is greatly influenced by the quality of the light curing unit (LCU) used. Commonly used halogen LCUs have some specific drawbacks such as decreasing light output with time. This may result in a low degree of monomer conversion of the composites with negative clinical implications. Previous studies have shown that blue light emitting diode (LED) LCUs have the potential to polymerize dental composites without having the drawbacks of halogen LCUs. Since these studies were carried out LED technology has advanced significantly and commercial LED LCUs are now becoming available. This study investigates the Barcol hardness as a function of depth, and the compressive strength of dental composites that had been polymerized for 40 or 20s with two high power LED LCU prototypes, a commercial LED LCU, and a commercial halogen LCU. In addition the radiometric properties of the LCUs were characterized. The two high power prototype LED LCUs and the halogen LCU showed a satisfactory and similar hardness-depth performance whereas the hardness of the materials polymerized with the commercial LED LCU rapidly decreased with sample depth and reduced polymerization time (20 s). There were statistically significant differences in the overall compressive strengths of composites polymerized with different LCUs at the 95% significance level (p = 0.0016) with the two high power LED LCU prototypes and the halogen LCU forming a statistically homogenous group. In conclusion, LED LCU polymerization technology can reach the performance level of halogen LCUs. One of the first commercial LED LCUs however lacked the power reserves of the high power LED LCU prototypes.

  5. Effect of light-curing unit and adhesive system on marginal adaptation of class v composite restorations.

    Science.gov (United States)

    Maia-Casseli, Denise S; Faria-e-Silva, André L; Cavalcanti, Andréa N; Romani, Eliene A O N; Martins, Luis R M

    2012-01-01

    The aim of this study was to evaluate the effect of light-curing units (LED or halogen) on the marginal adaptation of composite restorations performed with etch-and-rinse and self-etching adhesive. Class V cavities were prepared on bovine teeth with the gingival margin on dentin and the incisal margin on enamel. The cavities were restored with a micro-hybrid resin composite using an etch-and-rinse (Single Bond 2--SB) or a self-etching adhesive (Clearfil SE Bond--CL). The light-activations were performed using halogen lamp (Optilux 501--QTH) or second-generation light-emitting diode (Radii-Cal--LED) (n = 10). After finishing and polishing the restorations, epoxy replicas were prepared. The marginal adaptation was analyzed under scanning electronic microscopy with 500x of magnification. The greatest gap width at each margin was recorded. Data were submitted to Mann-Whitney and Wilcoxon tests (a = 0.05). SB and CL showed similar behavior of enamel margins when the light-activations were performed with QTH. The same was observed for dentin margins with LED. When the LED was used, higher gap measurements at enamel margins were observed with CL, while higher gap values in dentin were observed for SB within QTH. No significant difference between substrates was found when CL was used. However, SB had significantly higher gap measurements in dentin. The light-curing unit seems to affect the marginal adaptation of resin composite restorations. However this effect was dependent on the adhesive and the location of the margin.

  6. Light-Emitting Diodes (LED) for Primary Animal Habitat Lighting in Highly Controlled Environments

    Science.gov (United States)

    Winget, C. M.; Syrkin, N.; Heeke, D.; Mele, G.; Holley, D. C.; Dalton, Bonnie P. (Technical Monitor)

    1996-01-01

    Significant alterations in Biological Clock responses have been reported following sidereal time changes (e.g., Jet-lag), and exposure to microgravity (e.g., daytime sleepiness). Additionally, light reduces circulating melatonin (spectral specificity greatest between 450-500 nm). It was hypothesized that LEDs can replace the current light sources used in zero gravity and terrestrial research laboratories because of their small size, low mass, low energy consumption and long functional life. This report evaluates the capacity of LEDs to entrain the circadian system of rats as judged by measurement of overt behavioral circadian rhythms (activity, feeding, drinking). These data were collected in highly controlled environments similar to the shuttle Animal Enclosure Modules. Two groups were compared: control - animals exposed to standard cool-white fluorescent lights, and test - animals exposed to LEDs with a spectral power distribution matching the fluorescent lights. Gross locomotor activity, feeding and drinking frequencies were continuously monitored and stored at 10 minute intervals. Animals were exposed to the following photoperiods: 28 days of 12L:12D, 19 days of 24L:0D and 16 days of 12L:12D. Light intensities tested varied between 0.1 to 100 lux. Rats received food and water ad libitum, and temperature and humidity were controlled throughout the study. The general health status of all rats was acceptable for each day of this study. No incidents of aggressive behavior were observed. Growth, locomotor activity, food and water consumption were comparable for all groups of animals, i.e, the circadian characteristics of the animals under these conditions were comparable. These results indicate that LED arrays are as effective in maintaining circadian rhythm stability as the commonly used cool-white fluorescent light sources. LEDs with their flexible spectrum, low energy requirements and minimal heat production have advantages for some chronopharmacology studies and

  7. 3D printed UV light cured polydimethylsiloxane devices for drug delivery.

    Science.gov (United States)

    Holländer, Jenny; Hakala, Risto; Suominen, Jaakko; Moritz, Niko; Yliruusi, Jouko; Sandler, Niklas

    2017-11-09

    The goal of this work was to study the printability of PDMS with a semi-solid extrusion printer in combination with the UV-assisted crosslinking technology using UV-LED light to manufacture drug containing structures. Structures with different pore sizes and different drug loadings were prepared containing prednisolone as a model drug. The work showed that it was possible to print drug-free and drug-loaded drug delivery devices of PDMS with the 3D printing technique used in this study. The required UV-curing time to get sufficient crosslinking yield and mechanical strength was minimum three minutes. The microgram drug release from the printed structures was highest for the most drug loaded structures regardless of the porosity of the devices. By altering the surface area/volume ratio it was possible to print structures with differences in the release rate. This study shows that room-temperature semi-solid extrusion printing 3D printing technique in combination with UV-LED crosslinking is an applicable method in the production of prednisolone containing PDMS devices. Both the extrusion 3D printing and the UV-crosslinking was done at room temperature, which make this manufacturing method an interesting alternative for manufacturing controlled release devices containing temperature susceptible drugs. Copyright © 2017 Elsevier B.V. All rights reserved.

  8. Stability of the Light Output, Oral Cavity Tip Accessibility in Posterior Region and Emission Spectrum of Light-Curing Units.

    Science.gov (United States)

    André, C B; Nima, G; Sebold, M; Giannini, M; Price, R B

    2018-04-09

    This study evaluated the light output from six light-emitting diode dental curing lights after 25 consecutive light exposures without recharging the battery, tip accessibility in the posterior region, and light beam spread from light-curing units. Irradiance, spectral peak, and radiant exposure were measured with the battery fully charged (Bluephase Style, ESPE Cordless, Elipar S10, Demi Ultra, Valo Cordless, and Radii-Cal) and monitored for 25 light exposures (each lasting 10 seconds). The tip diameter was measured to identify the beam size and the ability of the six light-curing units to irradiate all areas of the lower second molar in the standard output setting. Four curing lights delivered a single peak wavelength from 454 to 462 nm, and two (Bluephase Style and Valo Cordless) delivered multiple emission peaks (at 410 and 458 nm and 400, 450, and 460 nm, respectively). The irradiance and radiant exposure always decreased after 25 exposures by 2% to 8%, depending on the light unit; however, only ESPE Cordless, Valo Cordless, and Radii-Cal presented a statistical difference between the first and the last exposure. The tip diameter ranged from 6.77 mm to 9.40 mm. The Radii-Cal delivered the lowest radiant exposure and irradiance. This light was also unable to access all the teeth with the tip parallel to the occlusal surface of the tooth. Not all of the blue-emitting lights deliver the same emission spectra, and some curing lights delivered a lower irradiance (as much as 8% lower) after the 25th exposure.

  9. Scale up sediment microbial fuel cell for powering Led lighting

    Directory of Open Access Journals (Sweden)

    Jeetendra Prasad

    2018-02-01

    Full Text Available Sediment microbial fuel cells (SMFCs are expected to be utilized as a sustainable power source for remote environmental observing 30 day’s investigations of experiment to understand the long-term performance of SMFCs. The point of this investigation is to increase power generation, 8 individual sediment microbial fuel cells is stacked together either in series or in hybrid connection. Two combinations, of the hybrid connection, are proving to be the more effective one, step-up both the voltage and current of the framework, mutually. Polarization curve tests are done for series and hybrid connected sediment microbial fuel cell. The maximum study state voltage and current are obtained 8.150V and 435.25µA from series and 4.078V and 870.75µA hybrid connected SMFC. This study suggests that power of SMFC scale-up by connecting series and hybrid for practical use of the device. Article History: Received : September 26th 2017; Received: December 24th 2017; Accepted: January 4th 2018; Available online How to Cite This Article: Prasad, J and Tripathi, R.K. (2018 Scale Up Sediment Microbial Fuel Cell For Powering Led Lighting. International Journal of Renewable Energy Development, 7(1, 53-58. https://doi.org/10.14710/ijred.7.1.53-58

  10. Influence of the light-curing unit, storage time and shade of a dental composite resin on the fluorescence

    Science.gov (United States)

    Queiroz, R. S.; Bandéca, M. C.; Calixto, L. R.; Gaiao, U.; Cuin, A.; Porto-Neto, S. T.

    2010-07-01

    The aim of this study was to determine the influence of three light-curing units, storage times and colors of the dental composite resin on the fluorescence. The specimens (diameter 10.0 ± 0.1 mm, thickness 1.0 ± 0.1 mm) were made using a stainless steel mold. The mold was filled with the microhybrid composite resin and a polyethylene film covered each side of the mold. After this, a glass slide was placed on the top of the mold. To standardize the top surface of the specimens a circular weight (1 kg) with an orifice to pass the light tip of the LCU was placed on the top surface and photo-activated during 40 s. Five specimens were made for each group. The groups were divided into 9 groups following the LCUs (one QTH and two LEDs), storage times (immediately after curing, 24 hours, 7 and 30 days) and colors (shades: A2E, A2D, and TC) of the composite resin. After photo-activation, the specimens were storage in artificial saliva during the storage times proposed to each group at 37°C and 100% humidity. The analysis of variance (ANOVA) and Tukey’s posthoc tests showed no significant difference between storage times (immediately, 24 hours and 30 days) ( P > 0.05). The means of fluorescence had difference significant to color and light-curing unit used to all period of storage ( P 0.05).

  11. Cytotoxicity of Light-Cured Dental Materials according to Different Sample Preparation Methods

    Directory of Open Access Journals (Sweden)

    Myung-Jin Lee

    2017-03-01

    Full Text Available Dental light-cured resins can undergo different degrees of polymerization when applied in vivo. When polymerization is incomplete, toxic monomers may be released into the oral cavity. The present study assessed the cytotoxicity of different materials, using sample preparation methods that mirror clinical conditions. Composite and bonding resins were used and divided into four groups according to sample preparation method: uncured; directly cured samples, which were cured after being placed on solidified agar; post-cured samples were polymerized before being placed on agar; and “removed unreacted layer” samples had their oxygen-inhibition layer removed after polymerization. Cytotoxicity was evaluated using an agar diffusion test, MTT assay, and confocal microscopy. Uncured samples were the most cytotoxic, while removed unreacted layer samples were the least cytotoxic (p < 0.05. In the MTT assay, cell viability increased significantly in every group as the concentration of the extracts decreased (p < 0.05. Extracts from post-cured and removed unreacted layer samples of bonding resin were less toxic than post-cured and removed unreacted layer samples of composite resin. Removal of the oxygen-inhibition layer resulted in the lowest cytotoxicity. Clinicians should remove unreacted monomers on the resin surface immediately after restoring teeth with light-curing resin to improve the restoration biocompatibility.

  12. Demonstration Assessment of Light-Emitting Diode (LED) Parking Lot Lighting in Leavenworth, KS

    Energy Technology Data Exchange (ETDEWEB)

    Myer, Michael; Kinzey, Bruce R.; Curry, Ku' uipo

    2011-05-06

    This report describes the process and results of a demonstration of solid-state lighting (SSL) technology in a commercial parking lot lighting application, under the U.S. Department of Energy (DOE) Solid-State Lighting Technology GATEWAY Demonstration Program. The parking lot is for customers and employees of a Walmart Supercenter in Leavenworth, Kansas and this installation represents the first use of the LED Parking Lot Performance Specification developed by the DOE’s Commercial Building Energy Alliance. The application is a parking lot covering more than a half million square feet, lighted primarily by light-emitting diodes (LEDs). Metal halide wall packs were installed along the building facade. This site is new construction, so the installed baseline(s) were hypothetical designs. It was acknowledged early on that deviating from Walmart’s typical design would reduce the illuminance on the site. Walmart primarily uses 1000W pulse-start metal halide (PMH) lamps. In order to provide a comparison between both typical design and a design using conventional luminaires providing a lower illuminance, a 400W PMH design was also considered. As mentioned already, the illuminance would be reduced by shifting from the PMH system to the LED system. The Illuminating Engineering Society of North America (IES) provides recommended minimum illuminance values for parking lots. All designs exceeded the recommended illuminance values in IES RP-20, some by a wider margin than others. Energy savings from installing the LED system compared to the different PMH systems varied. Compared to the 1000W PMH system, the LED system would save 63 percent of the energy. However, this corresponds to a 68 percent reduction in illuminance as well. In comparison to the 400W PMH system, the LED system would save 44 percent of the energy and provide similar minimum illuminance values at the time of relamping. The LED system cost more than either of the PMH systems when comparing initial costs

  13. Effect of different light curing units on Knoop hardness and temperature of resin composite

    OpenAIRE

    Guiraldo Ricardo; Consani Simonides; Xediek Consani Rafael; Mendes Wilson; Lympius Thais; Coelho Sinhoreti Mario

    2009-01-01

    Aim: To evaluate the influence of quartz tungsten halogen and plasma arc curing (PAC) lights on Knoop hardness and change in polymerization temperature of resin composite. Materials and Methods: Filtek Z250 and Esthet X composites were used in the shade A3. The temperature increase was registered with Type-k thermocouple connected to a digital thermometer (Iopetherm 46). A self-cured polymerized acrylic resin base was built in order to guide the thermocouple and to support the dentin disk ...

  14. Savings in Cooling Energy with a Thermal Management System for LED Lighting in Office Buildings

    Directory of Open Access Journals (Sweden)

    Byung-Lip Ahn

    2015-06-01

    Full Text Available Light-emitting diode (LED lighting should be considered for lighting efficiency enhancement, however, waste heat from light-emitting diode (LED lighting increases the internal cooling load during the summer season. In order to solve this problem we propose a thermal management system for light-emitting diode (LED lighting with a heat exchanger module integrated with the building’s heating, ventilation, and air conditioning (HVAC system to move the lighting’s waste heat outdoors. An experiment was carried out to investigate the thermal effects in a test chamber and the heat exchange rate between the heat sink and the duct air. The heat generated by the light-emitting diode (LED lighting was calculated as 78.1% of light-emitting diode (LED input power and the heat exchange rate of the lighting heat exchange module was estimated to be between 86.5% and 98.1% according to the light-emitting diode (LED input power and the flow rate of air passing the heat sink. As a result, the average light-emitting diode (LED lighting heat contribution rate for internal heat gain was determined as 0.05; this value was used to calculate the heating and cooling energy demand of the office building through an energy simulation program. In the simulation results, the cooling energy demand was reduced by 19.2% compared with the case of conventionally installed light-emitting diode (LED lighting.

  15. 77 FR 69499 - Certain LED Photographic Lighting Devices and Components Thereof; Notice of the Commission's...

    Science.gov (United States)

    2012-11-19

    ... COMMISSION Certain LED Photographic Lighting Devices and Components Thereof; Notice of the Commission's... certain LED photographic lighting devices and components thereof that infringe certain claims of U.S..., LLC d/b/a Cool Lights, USA of Reno, Nevada; Elation Lighting, Inc. of Los Angeles, California...

  16. Effect of LED light quality on in vitro shoot proliferation and growth of ...

    African Journals Online (AJOL)

    As an alternative to conventional lighting systems, light emitting diode (LED) has been demonstrated to be an artificial flexible lighting source for commercial micropropagation. The objective of this study was to determine the effects of different LED light quality on in vitro shoot proliferation and growth of Vanilla planifolia.

  17. Effect of cement shade and light-curing unit on bond strength of a ceramic cemented to dentin.

    Science.gov (United States)

    de Castro, Humberto Lago; Passos, Sheila Pestana; Zogheib, Lucas Villaça; Bona, Alvaro Della

    2012-04-01

    To evaluate the effect of cement shade, light-curing unit, and water storage on tensile bond strength (σ) of a feldspathic ceramic resin bonded to dentin. The dentin surface of 40 molars was exposed and etched with 37% phosphoric acid, then an adhesive system was applied. Forty blocks of feldspathic ceramic (Vita VM7) were produced. The ceramic surface was etched with 10% hydrofluoric acid for 60 s, followed by the application of a silane agent and a dual-curing resin cement (Variolink II). Ceramic blocks were cemented to the treated dentin using either A3 or transparent (Tr) shade cement that was activated using either halogen or LED light for 40 s. All blocks were stored in 37°C distilled water for 24 h before cutting to obtain non-trimmed bar-shaped specimens (adhesive area = 1 mm2 ± 0.1) for the microtensile bond strength test. The specimens were randomly grouped according to the storage time: no storage or stored for 150 days in 37°C distilled water. Eight experimental groups were obtained (n = 30). The specimens were submitted to the tensile bond strength test using a universal testing machine at a crosshead speed of 1 mm/min. The data were statistically analyzed using ANOVA and Tukey's posthoc tests (a = 0.05). The mean bond strength values were significantly lower for the corresponding water stored groups, except for the specimens using A3 resin cement activated by halogen light. There was no significance difference in mean bond strength values among all groups after water storage. Water storage had a detrimental effect under most experimental conditions. For both cement shades investigated (Tr and A3) under the same storage condition, the light-curing units (QTH and LED) did not affect the mean microtensile bond strengths of resin-cemented ceramic to dentin.

  18. Fundamentals of solid-state lighting LEDs, OLEDs, and their applications in illumination and displays

    CERN Document Server

    Khanna, Vinod Kumar

    2014-01-01

    History and Basics of LightingChronological History of LightingLearning Objectives How Early Man Looked at the ""Sun"" The Need for Artificial Light Sources First Steps in the Evolution of Artificial Lighting The First Solid-State Lighting Device The First Practical Electrical Lighting Device The Incandescent Filament Lamp Mercury and Sodium Vapor Lamps The Fluorescent Lamp The Compact Fluorescent Lamp Revolution in the World of Lighting: Advent of Light-Emitting Diodes Birth of the First LED and the Initial Stages of LED Development The Father of the LED: Holonyak Jr. The Post-1962 Developmen

  19. Demonstration Assessment of Light-Emitting Diode (LED) Roadway Lighting on Lija Loop in Portland, OR

    International Nuclear Information System (INIS)

    Kinzey, Bruce R.; Myer, Michael

    2009-01-01

    This report describes the process and results of a demonstration of solid-state lighting (SSL) technology in a residential street lighting application, under the U.S. Department of Energy GATEWAY Solid-State Lighting Technology Demonstration Program. In this project, eight 100W (nominal) high-pressure sodium cobra head fixtures were replaced with a like number of LED street light luminaires manufactured by Leotek, Inc. The Leotek product achieved an estimated payback in the Lija Loop installation of about 20 years for replacement scenarios and a much shorter 7.6 years for new installations. Much of the associated energy savings (55%) supporting these payback periods, however, were achieved by reducing average horizontal photopic illuminance a similar amount (53%). Examined from a different perspective, the measured performance suggests that the Leotek product is at approximate parity with the HPS cobra head in terms of average delivered photopic illumination for a given power consumption. HPS comprises the second most efficacious street lighting technology available, exceeded only by low pressure sodium (LPS). LPS technology is not considered suitable for most street lighting applications due to its monochromatic spectral output and poor color rendering ability; therefore, this LED product is performing at an efficiency level comparable to its primary competition in this application.

  20. Development of Key Technologies for White Lighting Based on Light-Emitting Diodes (LEDs)

    Energy Technology Data Exchange (ETDEWEB)

    Werner Goetz; Bill Imler; James Kim; Junko Kobayashi; Andrew Kim; Mike Krames; Rick Mann; Gerd Mueller-Mach; Anneli Munkholm; Jonathan Wierer

    2004-03-31

    This program was organized to focus on materials development issues critical to the acceleration of solid-state lighting, and was split into three major thrust areas: (1) study of dislocation density reduction for GaN grown on sapphire using 'cantilever epitaxy', and the impact of dislocation density on the performance of state-of-the-art high-power LEDs; (2) the evaluation of in situ techniques for monitoring gas phase chemistry and the properties of GaN-based layers during metal-organic vapor phase epitaxy (MOCVD), and (3) feasibility for using semiconductor nanoparticles ('quantum dots') for the down-conversion of blue or ultraviolet light to generate white light. The program included a partnership between Lumileds Lighting (epitaxy and device fabrication for high power LEDs) and Sandia National Laboratories (cantilever epitaxy, gas phase chemistry, and quantum dot synthesis). Key findings included: (1) cantilever epitaxy can provide dislocation density reduction comparable to that of more complicated approaches, but all in one epitaxial growth step; however, further improvements are required to realize significant gains in LED performance at high drive currents, (2) in situ tools can provide detailed knowledge about gas phase chemistry, and can be used to monitor and control epitaxial layer composition and temperature to provide improved yields (e.g., a fivefold increase in color targeting is demonstrated for 540nm LEDs), and (3) quantum efficiency for quantum dots is improved and maintained up to 70% in epoxy thin films, but further work is necessary to increase densification (absorption) and robustness before practical application to LEDs.

  1. Light-induced retinal damage using different light sources, protocols and rat strains reveals LED phototoxicity.

    Science.gov (United States)

    Krigel, A; Berdugo, M; Picard, E; Levy-Boukris, R; Jaadane, I; Jonet, L; Dernigoghossian, M; Andrieu-Soler, C; Torriglia, A; Behar-Cohen, F

    2016-12-17

    To save energy, the European directives from the Eco-design of Energy Using Products (2005/32/CE) have recommended the replacement of incandescent lamps by more economic devices such as Light Emitting Diodes (LEDs). However, the emission spectrum of these devices is enriched in blue radiations, known to be potentially dangerous to the retina. Recent studies showed that light exposure contributes to the onset of early stages of age-related macular degeneration (AMD). Here, we investigate, in albinos and pigmented rats, the effects of different exposure protocols. Twenty-four hours exposure at high luminance was compared to a cyclic (dark/light) exposure at domestic levels for 1week and 1month, using different LEDs (Cold-white, blue and green), as well as fluorocompact bulbs and fluorescent tubes. The data suggest that the blue component of the white-LED may cause retinal toxicity at occupational domestic illuminance and not only in extreme experimental conditions, as previously reported. It is important to note that the current regulations and standards have been established on the basis of acute light exposure and do not take into account the effects of repeated exposure. Copyright © 2016 IBRO. Published by Elsevier Ltd. All rights reserved.

  2. Monte carlo analysis of multicolour LED light engine

    DEFF Research Database (Denmark)

    Chakrabarti, Maumita; Thorseth, Anders; Jepsen, Jørgen

    2015-01-01

    A new Monte Carlo simulation as a tool for analysing colour feedback systems is presented here to analyse the colour uncertainties and achievable stability in a multicolour dynamic LED system. The Monte Carlo analysis presented here is based on an experimental investigation of a multicolour LED...

  3. Light emitting diodes (LED): applications in forest and native plant nurseries

    Science.gov (United States)

    Thomas D. Landis; Jeremiah R. Pinto; R. Kasten Dumroese

    2013-01-01

    It was quotes like this that made us want to learn more about light emitting diodes (LED). Other than knowing that LEDs were the latest innovation in artificial lighting, we knew that we had a lot to learn. So we started by reviewing some of the basics. The following review is a brief synopsis of how light affects plants and some discussion about LED lighting. If you...

  4. Energy Efficient LED Spectrally Matched Smart Lighting, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — Innovative Imaging and Research has teamed with the University of Southern Mississippi to develop a novel energy efficient smart light system. Smart lighting adds an...

  5. Newly patented process enables low-cost solution for increasing white light spectrum of LEDs

    Science.gov (United States)

    Spanard, Jan-Marie

    2017-10-01

    A newly patented process for completing the spectral light array emitted by LED bulbs provides a low-cost method for producing better human centered lighting (HCL). This process uses non-luminescent colorant filters, filling out the jagged LED spectral emission into a full, white light array. While LED bulbs have the distinct economic advantages of using less energy, producing less heat and lasting years longer than traditional incandescent bulbs, the persistent metameric failure of LED bulbs has resulted in slower, and sometimes reluctant, adoption of LED lighting by the residential, retail and architectural markets. Adding missing wavelengths to LED generated bulbs via colorant filters increases the aesthetic appeal of the light by decreasing current levels of metameric failure, reducing the `flatness', `harshness', and `dullness' of LED generated light reported by consumers. LED phosphor-converted light can be successfully tuned to "whiter" white light with selective color filtering using permanent, durable transparent pigments. These transparent pigments are selectively applied in combination with existing manufacturing technologies and utilized as a final color-tuning step in bulb design. The quantity of emitted light chosen for color filtering can be adjusted from 1% to 100% of emitted light, creating a custom balance of light quantity with light quality. This invention recognizes that "better light" is frequently chosen over "more light" in the consumer marketplace.

  6. Power density of various light curing units through resin inlays with modified layer thickness

    Science.gov (United States)

    Hong, Sung-Ok; Oh, Yonghui; Min, Jeong-Bum; Kim, Jin-Woo; Lee, Bin-Na; Hwang, Yun-Chan; Hwang, In-Nam; Oh, Won-Mann

    2012-01-01

    Objectives The purpose of this study was to enhance curing light penetration through resin inlays by modifying the thicknesses of the dentin, enamel, and translucent layers. Materials and Methods To investigate the layer dominantly affecting the power density of light curing units, resin wafers of each layer with 0.5 mm thickness were prepared and power density through resin wafers was measured with a dental radiometer (Cure Rite, Kerr). The dentin layer, which had the dominant effect on power density reduction, was decreased in thickness from 0.5 to 0.1 mm while thickness of the enamel layer was kept unchanged at 0.5 mm and thickness of the translucent layer was increased from 0.5 to 0.9 mm and vice versa, in order to maintain the total thickness of 1.5 mm of the resin inlay. Power density of various light curing units through resin inlays was measured. Results Power density measured through 0.5 mm resin wafers decreased more significantly with the dentin layer than with the enamel and translucent layers (p inlays increased when the dentin layer thickness was reduced and the enamel or translucent layer thickness was increased. The highest power density was recorded with dentin layer thickness of 0.1 mm and increased translucent layer thickness in all light curing units. Conclusions To enhance the power density through resin inlays, reducing the dentin layer thickness and increasing the translucent layer thickness would be recommendable when fabricating resin inlays. PMID:23431061

  7. LED Light Characteristics for Surgical Shadowless Lamps and Surgical Loupes

    OpenAIRE

    Ide, Takeshi; Kinugawa, Yoshitaka; Nobae, Yuichi; Suzuki, Toshihiro; Tanaka, Yoshiyuki; Toda, Ikuko; Tsubota, Kazuo

    2015-01-01

    Background: Blue light has more energy than longer wavelength light and can penetrate the eye to reach the retina. When surgeons use magnifying loupes under intensive surgical shadowless lamps for better view of the surgical field, the total luminance is about 200 times brighter than that of typical office lighting. In this study, the effects of 2 types of shadowless lamps were compared. Moreover, the effect of various eyeglasses, which support magnifying loupes, on both the light energy and ...

  8. Fluorescent light induces neurodegeneration in the rodent nigrostriatal system but near infrared LED light does not.

    Science.gov (United States)

    Romeo, Stefania; Vitale, Flora; Viaggi, Cristina; di Marco, Stefano; Aloisi, Gabriella; Fasciani, Irene; Pardini, Carla; Pietrantoni, Ilaria; Di Paolo, Mattia; Riccitelli, Serena; Maccarone, Rita; Mattei, Claudia; Capannolo, Marta; Rossi, Mario; Capozzo, Annamaria; Corsini, Giovanni U; Scarnati, Eugenio; Lozzi, Luca; Vaglini, Francesca; Maggio, Roberto

    2017-05-01

    We investigated the effects of continuous artificial light exposure on the mouse substantia nigra (SN). A three month exposure of C57Bl/6J mice to white fluorescent light induced a 30% reduction in dopamine (DA) neurons in SN compared to controls, accompanied by a decrease of DA and its metabolites in the striatum. After six months of exposure, neurodegeneration progressed slightly, but the level of DA returned to the basal level, while the metabolites increased with respect to the control. Three month exposure to near infrared LED light (∼710nm) did not alter DA neurons in SN, nor did it decrease DA and its metabolites in the striatum. Furthermore mesencephalic cell viability, as tested by [ 3 H]DA uptake, did not change. Finally, we observed that 710nm LED light, locally conveyed in the rat SN, could modulate the firing activity of extracellular-recorded DA neurons. These data suggest that light can be detrimental or beneficial to DA neurons in SN, depending on the source and wavelength. Copyright © 2017 Elsevier B.V. All rights reserved.

  9. Physical properties of self-, dual-, and light-cured direct core materials.

    Science.gov (United States)

    Rüttermann, Stefan; Alberts, Ian; Raab, Wolfgang H M; Janda, Ralf R

    2011-08-01

    The objective of this study is to evaluate flexural strength, flexural modulus, compressive strength, curing temperature, curing depth, volumetric shrinkage, water sorption, and hygroscopic expansion of two self-, three dual-, and three light-curing resin-based core materials. Flexural strength and water sorption were measured according to ISO 4049, flexural modulus, compressive strength, curing temperature, and curing depth according to well-proven, literature-known methods, and the volumetric behavior was determined by the Archimedes' principle. ANOVA was calculated to find differences between the materials' properties, and correlation of water sorption and hygroscopic expansion was analysed according to Pearson (p hygroscopic expansion (0.0 ± 0.2 vol.%). Clearfil Photo Core and Encore SuperCure Contrast demonstrated the lowest shrinkage (≈2.1 ± 0.1 vol.%). Water sorption and hygroscopic expansion had a very strong positive correlation. The investigated core materials significantly differed in the tested properties. The performance of the materials depended on their formulation, as well as on the respective curing process.

  10. LED intense headband light source for fingerprint analysis

    Science.gov (United States)

    Villa-Aleman, Eliel

    2005-03-08

    A portable, lightweight and high-intensity light source for detecting and analyzing fingerprints during field investigation. On-site field analysis requires long hours of mobile analysis. In one embodiment, the present invention comprises a plurality of light emitting diodes; a power source; and a personal attachment means; wherein the light emitting diodes are powered by the power source, and wherein the power source and the light emitting diodes are attached to the personal attachment means to produce a personal light source for on-site analysis of latent fingerprints. The present invention is available for other applications as well.

  11. Large area flexible lighting foils using distributed bare LED dies on polyester substrates

    NARCIS (Netherlands)

    Ende, D.A. van den; Kusters, R.H.L.; Cauwe, M.; Waal, A. van der; Brand, J. van den

    2013-01-01

    Integration of LEDs on flexible foil substrates is of interest for flexible lighting applications and for backlights for flexible displays. Such a large area lighting device can be made by integrating a matrix of closely spaced LEDs on a flexible foil substrate. Preferably, these LEDs are integrated

  12. Bonding bare die LEDs on PET foils for lighting applications: Thermal design modeling and bonding experiments

    NARCIS (Netherlands)

    Ende, D.A. van den; Kusters, R.H.L.; Cauwe, M.; Waal, A. van der; Brand, J. van den

    2012-01-01

    Integration of LEDs on flexible foil substrates is of interest for flexible lighting applications and flexible photonic devices. A matrix of LEDs on a foil combined with a diffuser can be a potential alternative for flexible OLED lighting devices. Preferably, these LEDs are integrated in an

  13. Preparation of low viscosity epoxy acrylic acid photopolymer prepolymer in light curing system

    Science.gov (United States)

    Li, P.; Huang, J. Y.; Liu, G. Z.

    2018-01-01

    With the integration and development of materials engineering, applied mechanics, automatic control and bionics, light cured composite has become one of the most favourite research topics in the field of materials and engineering at home and abroad. In the UV curing system, the prepolymer and the reactive diluent form the backbone of the cured material together. And they account for more than 90% of the total mass. The basic properties of the cured product are mainly determined by the prepolymer. A low viscosity epoxy acrylate photosensitive prepolymer with a viscosity of 6800 mPa • s (25 °C ) was obtained by esterification of 5 hours with bisphenol A epoxy resin with high epoxy value and low viscosity.

  14. LED Retrofit Kits, TLEDs, and Lighting Controls: An Application Guide

    Energy Technology Data Exchange (ETDEWEB)

    None

    2017-03-01

    This document provides guidance for retrofitting existing fluorescent troffers including the LED and associated control options available, the pro/cons and costs/benefits of each option, and agency specific requirements (where applicable).

  15. Light Emitting Diode (LED) circular traffic signal lifetime management system.

    Science.gov (United States)

    2011-02-01

    The objective of this research is to build lifetime curves for red, yellow, and green LED circular traffic signals through 20,000-hr. accelerated stress testing of samples operating under Louisianas environmental conditions.

  16. Influence of energy density of different light sources on knoop hardness of a dual-cured resin cement

    Directory of Open Access Journals (Sweden)

    Evandro Piva

    2008-06-01

    Full Text Available The purpose of this study was to evaluate the Knoop hardness of a dual-cured resin-based luting cement irradiated with different light sources as well energy density through a ceramic sample. Three light-curing unit (LCUs were tested: tungsten halogen light (HAL, light-emitting diode (LED and xenon plasma-arc (PAC lamp. Disc-shaped specimens were fabricated from a resin-based cement (Enforce. Three energy doses were used by modifying the irradiance (I of each LCU and the irradiation time (T: 24 Jcm-2 (I/2x2T, 24 Jcm-2 (IxT and 48 Jcm-2 (Ix2T. Energy doses were applied through a 2.0-mm-thick ceramic sample (Duceram Plus. Three groups underwent direct irradiation over the resin cement with the different LCUs and a chemically-activated group served as a control. Thirteen groups were tested (n=10. Knoop hardness number (KHN means were obtained from cross-sectional areas. Two-way ANOVA and the Holm-Sidak method were used for statistical comparisons of activation mode and energy doses (a=5%. Application of 48 J.cm-2 energy dose through the ceramic using LED (50.5±2.8 and HAL (50.9±3.7 produced significantly higher KHN means (p<0.05 than the control (44.7±3.8. LED showed statistically similar performance to HAL. Only HAL showed a relationship between the increase of LCU energy dose and hardness increase.

  17. Spectra Analysis in Sunset Color Demonstrations with a White-Color LED as a Light Source

    OpenAIRE

    Makoto Hasegawa; Seika Tokumitsu

    2016-01-01

    Spectra of light beams emitted from white-color LED torches are different from those of conventional electric torches. In order to confirm if white-color LED torches can be used as light sources for popular sunset color demonstrations in spite of such differences, spectra of travelled light beams and scattered light beams with each of a white-color LED torch (composed of a blue LED and yellow-color fluorescent material) and a conventional electric torch as a light source were measured and com...

  18. Biological Research in Canisters (BRIC) - Light Emitting Diode (LED)

    Science.gov (United States)

    Levine, Howard G.; Caron, Allison

    2016-01-01

    The Biological Research in Canisters - LED (BRIC-LED) is a biological research system that is being designed to complement the capabilities of the existing BRIC-Petri Dish Fixation Unit (PDFU) for the Space Life and Physical Sciences (SLPS) Program. A diverse range of organisms can be supported, including plant seedlings, callus cultures, Caenorhabditis elegans, microbes, and others. In the event of a launch scrub, the entire assembly can be replaced with an identical back-up unit containing freshly loaded specimens.

  19. The Involvement of the Oxidative Stress in Murine Blue LED Light-Induced Retinal Damage Model.

    Science.gov (United States)

    Nakamura, Maho; Kuse, Yoshiki; Tsuruma, Kazuhiro; Shimazawa, Masamitsu; Hara, Hideaki

    2017-01-01

    The aim of study was to establish a mouse model of blue light emitting diode (LED) light-induced retinal damage and to evaluate the effects of the antioxidant N-acetylcysteine (NAC). Mice were exposed to 400 or 800 lx blue LED light for 2 h, and were evaluated for retinal damage 5 d later by electroretinogram amplitude and outer nuclear layer (ONL) thickness. Additionally, we investigated the effect of blue LED light exposure on shorts-wave-sensitive opsin (S-opsin), and rhodopsin expression by immunohistochemistry. Blue LED light induced light intensity dependent retinal damage and led to collapse of S-opsin and altered rhodopsin localization from inner and outer segments to ONL. Conversely, NAC administered at 100 or 250 mg/kg intraperitoneally twice a day, before dark adaptation and before light exposure. NAC protected the blue LED light-induced retinal damage in a dose-dependent manner. Further, blue LED light-induced decreasing of S-opsin levels and altered rhodopsin localization, which were suppressed by NAC. We established a mouse model of blue LED light-induced retinal damage and these findings indicated that oxidative stress was partially involved in blue LED light-induced retinal damage.

  20. The Use of Light-Emitting Diodes (LEDs) as Green and Red/Far-Red Light Sources in Plant Physiology.

    Science.gov (United States)

    Jackson, David L.; And Others

    1985-01-01

    The use of green, red, and far-red light-emitting diodes (LEDs) as light sources for plant physiological studies is outlined and evaluated. Indicates that LED lamps have the advantage over conventional light sources in that they are lightweight, low-cost, portable, easily constructed, and do not require color filters. (Author/DH)

  1. Demonstration Assessment of Light-Emitting Diode (LED) Roadway Lighting, I-35W Bridge, Minneapolis, Minnesota, Phase I Report

    Energy Technology Data Exchange (ETDEWEB)

    Kinzey, B. R. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Myer, M. A. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2009-08-01

    On the I-35W Bridge in Minneapolis, Minnesota, the GATEWAY program conducted a two-phase demonstration of LED roadway lighting on the main span, which is one of the country's oldest continuously operated exterior LED lighting installations. The Phase I report provides an overview of initial project results including lighting performance, economic performance, and potential energy savings.

  2. Influence of light curing unit and ceramic thickness on temperature rise during resin cement photo-activation.

    Science.gov (United States)

    Guiraldo, Ricardo Danil; Consani, Simonides; Mastrofrancisco, Sarina; Consani, Rafael Leonardo Xediek; Sinhoreti, Mario Alexandre Coelho; Correr-Sobrinho, Lourenço

    2008-11-01

    The aim of this study was to determine the effect of different ceramic thickness on heat generation during resin cement photo-activation by QTH (quartz-tungsten-halogen), LED (light emitting diode), and PAC (plasma arc-curing) LCUs (light curing units). The resin cement used was Rely X ARC (3M-ESPE), and the ceramic was IPS Empress Esthetic (Ivoclar-Vivadent), of which 0.7-, 1.4- and 2.0-mm thick disks, 0.8 mm in diameter were made. Temperature increase was recorded with a type-K thermocouple connected to a digital thermometer (Iopetherm 46). An acrylic resin base was built to guide the thermocouple and support the 1.0-mm thick dentin disk. A 0.1-mm thick black adhesive paper matrix with a perforation 6 mm in diameter was placed on the dentin to contain the resin cement and support the ceramic disks of different thicknesses. Three LCUs were used: QTH, LED and PAC. Nine groups were formed (n=10) according to the interaction: 3 ceramic thicknesses, 1 resin cement and 3 photo-activation methods. Temperature increase data were submitted to Tukey's test (5%). For all ceramic thicknesses, a statistically significant difference in temperature increase was observed among the LCUs, with the highest mean value for the QTH LCU (p0.05). The interaction of higher energy density with smaller ceramic thickness showed higher temperature increase values.

  3. [Effect of different light of LED light quality on growth and antioxidant enzyme activities of Ganoderma lucidum].

    Science.gov (United States)

    Wang, Lihua; Chen, Xiangdong; Wang, Qiuyin; Hao, Junjiang; Lan, Jin

    2011-09-01

    To study the effect of light quality on growth, antioxidant enzyme activities of Ganoderma lucidum mycelium. G. lucidum mycelium was cultured under different light qualities by light emitting diodes (LED). The growth G. lucidum mycelium was observed and antioxidant enzyme activities was determined in different growth periods. Under the red LED, the blue LED and dark condition (CK), the mycelium grew faster than that under other light qualities. The white LED resulted in a largest increase in the amount of the mycelium and always kept the activities of CAT high level. Major fluctuations of POD activities emerged under the green LED, while enhanced severely in the late phase. Under the yellow LED, the activities of SOD appeared high level. However, SOD activities on dark (CK) raised obviously in late period. At the late stage, the content of mycelium polysaccharides was significant higher than that under the blue LED. The light quality could influence the growth and metabolism of G. lucidum mycelium.

  4. Effect of Different Thicknesses of Pressable Ceramic Veneers on Polymerization of Light-cured and Dual-cured Resin Cements

    Science.gov (United States)

    Cho, Seok-Hwan; Lopez, Arnaldo; Berzins, David W.; Prasad, Soni; Ahn, Kwang Woo

    2015-01-01

    Aim This study evaluated the effects of ceramic veneer thicknesses on the polymerization of two different resin cements. Materials and Methods A total of 80 ceramic veneer discs were fabricated by using a pressable ceramic material (e.max Press; Ivoclar Vivadent) from a Low Translucency (LT) ingot (A1 shade). These discs were divided into light-cured (LC; NX3 Nexus LC; Kerr) and dual-cured (DC; NX3 Nexus DC; Kerr) and each group was further divided into 4 subgroups, based on ceramic disc thickness (0.3 mm, 0.6 mm, 0.9 mm, and 1.2 mm). The values of Vickers microhardness (MH) and degree of conversion (DOC) were obtained for each specimen after a 24-hour storage period. Association between ceramic thickness, resin cement type, and light intensity readings (mW/cm2) with respect to microhardness and degree of conversion was statistically evaluated by using ANOVA. Results For the DOC values, there was no significant difference observed among the LC resin cement subgroups, except in the 1.2 mm subgroup; only the DOC value (14.0 ± 7.4%) of 1.2 mm DC resin cement had significantly difference from that value (28.9 ± 7.5%) of 1.2 mm LC resin cement (Presin cement groups, there was statistically significant difference (Presin cement groups demonstrated higher values than DC resin cement groups. On the other hands, among the DC resin cement subgroups, the MH values of 1.2 mm DC subgroup was significantly lower than the 0.3 mm and 0.6 mm subgroups (P.05). Conclusion The degree of conversion and hardness of the resin cement was unaffected with veneering thicknesses between 0.3 and 0.9 mm. However, the DC resin cement group resulted in a significantly lower DOC and MH values for the 1.2 mm subgroup. Clinical Significance While clinically adequate polymerization of LC resin cement can be achieved with a maximum 1.2 mm of porcelain veneer restoration, the increase of curing time or light intensity is clinically needed for DC resin cements at the thickness of more than 0.9 mm

  5. Histological Study of Open Wound Healing with a Light Cure Instrument

    Directory of Open Access Journals (Sweden)

    Vahid Changizi

    2010-09-01

    Full Text Available Introduction: In the present study, the effects of light cure on wound healing of mice’s skin with complete thickness were studied. Materials and Methods: Forty male mice of NMRI race were placed randomly into two groups of examination and control. Under aseptic and unconscious conditions, a circular wound of 6 mm width with complete thickness of skin was made on the back of each mice. The surgery day was established as day zero. Blue light of wavelength 420-500 nm from a light cure instrument was shined onto all the mice from the first day. Over the 3rd, 7th, 10th, 15th and 21st days after curing, four kinds of wound and healthy skins were taken from each mice. The practical procedures of general histology were applied on the samples, then slices of 5 micron thickness were taken from them and finally, they were colored with Hematoxline Eosin. The cell population of wound bed including fibroblast cells, macrophages, neutrophils and endothelia of vessels were studied. Results: The examination group showed significantly increased fibrosis and decreased inflammation (p≤0.05. Conclusion: Halogen blue light (light cure causes significant early open wound healing of skin with complete thickness.

  6. Conduction-driven cooling of LED-based automotive LED lighting systems for abating local hot spots

    Science.gov (United States)

    Saati, Ferina; Arik, Mehmet

    2018-02-01

    Light-emitting diode (LED)-based automotive lighting systems pose unique challenges, such as dual-side packaging (front side for LEDs and back side for driver electronics circuit), size, harsh ambient, and cooling. Packaging for automotive lighting applications combining the advanced printed circuit board (PCB) technology with a multifunctional LED-based board is investigated with a focus on the effect of thermal conduction-based cooling for hot spot abatement. A baseline study with a flame retardant 4 technology, commonly known as FR4 PCB, is first compared with a metal-core PCB technology, both experimentally and computationally. The double-sided advanced PCB that houses both electronics and LEDs is then investigated computationally and experimentally compared with the baseline FR4 PCB. Computational models are first developed with a commercial computational fluid dynamics software and are followed by an advanced PCB technology based on embedded heat pipes, which is computationally and experimentally studied. Then, attention is turned to studying different heat pipe orientations and heat pipe placements on the board. Results show that conventional FR4-based light engines experience local hot spots (ΔT>50°C) while advanced PCB technology based on heat pipes and thermal spreaders eliminates these local hot spots (ΔT<10°C), leading to a higher lumen extraction with improved reliability. Finally, possible design options are presented with embedded heat pipe structures that further improve the PCB performance.

  7. White light-emitting diodes (LEDs) at domestic lighting levels and retinal injury in a rat model.

    Science.gov (United States)

    Shang, Yu-Man; Wang, Gen-Shuh; Sliney, David; Yang, Chang-Hao; Lee, Li-Ling

    2014-03-01

    Light-emitting diodes (LEDs) deliver higher levels of blue light to the retina than do conventional domestic light sources. Chronic exposure to high-intensity light (2,000-10,000 lux) has previously been found to result in light-induced retinal injury, but chronic exposure to relatively low-intensity (750 lux) light has not been previously assessed with LEDs in a rodent model. We examined LED-induced retinal neuronal cell damage in the Sprague-Dawley rat using functional, histological, and biochemical measurements. We used blue LEDs (460 nm) and full-spectrum white LEDs, coupled with matching compact fluorescent lights, for exposures. Pathological examinations included electroretinogram, hematoxylin and eosin (H&E) staining, immunohistochemistry (IHC), and transmission electron microscopy (TEM). We also measured free radical production in the retina to determine the oxidative stress level. H&E staining and TEM revealed apoptosis and necrosis of photoreceptors, which indicated blue-light induced photochemical injury of the retina. Free radical production in the retina was increased in LED-exposed groups. IHC staining demonstrated that oxidative stress was associated with retinal injury. Although we found serious retinal light injury in LED groups, the compact fluorescent lamp (CFL) groups showed moderate to mild injury. Our results raise questions about adverse effects on the retina from chronic exposure to LED light compared with other light sources that have less blue light. Thus, we suggest a precautionary approach with regard to the use of blue-rich "white" LEDs for general lighting. Shang YM, Wang GS, Sliney D, Yang CH, Lee LL. 2014. White light-emitting diodes (LEDs) at domestic lighting levels and retinal injury in a rat model. Environ Health Perspect 122:269-276; http://dx.doi.org/10.1289/ehp.1307294.

  8. The effect of light-cured nanofilled composite resin shades on their under-surface temperature

    Science.gov (United States)

    Hanum, U. A.; Herda, E.; Indrani, D. J.

    2017-08-01

    The objective of this study was to observe the effect of shades of light-cured nanofilled composite resins on their under-surface temperature. Resin composites specimens of shades bright, medium, and dark shade were obtained from a cylindrical mold. While polymerizing using a curing unit, the under-surface temperature was determined at the bottom of the specimens using a thermocouple wire 20 sec after the start. Results showed that the under-surface temperature of the darker shade specimens were relatively higher that those of the brighter shades with significant diffferences between the resin composites of different shades. To conlude, the under-surface temperature of the light-cured nanofilled resin composites raised from the brighter to the darker shades.

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

    Science.gov (United States)

    Groves, Ethan; Palenik, Christopher S

    2016-03-01

    This study discusses the results of an evaluation of a one-part blue light-curing acrylic resin for embedding trace evidence prior to the preparation of thin sections with a microtome. Through a comparison to several epoxy resins, the physical properties relevant to both trace evidence examination and analytical microscopy in general, including as viscosity, clarity, color, hardness, and cure speed, were explored. Finally, thin sections from paint samples embedded in this acrylic resin were evaluated to determine if, through smearing or impregnation, the resin contributed to the infrared spectra. The results of this study show that blue light-curing acrylic resins provide the desired properties of an embedding medium, generate high-quality thin sections, and can significantly simplify the preparation of paint chips, fibers and a multitude of other types of microscopic samples in the forensic trace evidence laboratory. © 2015 American Academy of Forensic Sciences.

  10. Liquid cooling applications on automotive exterior LED lighting

    Science.gov (United States)

    Aktaş, Mehmet; Şenyüz, Tunç; Şenyıldız, Teoman; Kılıç, Muhsin

    2018-02-01

    In this study cooling of a LED unit with heatsink and liquid cooling block which is used in automotive head lamp applications has been investigated numerically and experimentally. Junction temperature of a LED which is cooled with heatsink and liquid cooling block obtained in the experiment. 23°C is used both in the simulation and the experiment phase. Liquid cooling block material is choosed aluminium (Al) and polyamide. All tests and simulation are performed with three different flow rate. Temperature distribution of the designed product is investigated by doing the numerical simulations with a commercially software. In the simulations, fluid flow is assumed to be steady, incompressible and laminar and 3 dimensional (3D) Navier-Stokes equations are used. According to the calculations it is obtained that junction temperature is higher in the heatsink design compared to block cooled one. By changing the block material, it is desired to investigate the variation on the LED junction temperature. It is found that more efficient cooling can be obtained in block cooling by using less volume and weight. With block cooling lifetime of LED can be increased and flux loss can be decreased with the result of decreased junction temperature.

  11. Energy Efficient LED Spectrally Matched Smart Lighting, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — Innovative Imaging and Research and the University of Houston Clear Lake have teamed to develop a widely extensible, affordable, energy efficient, smart lighting...

  12. GATEWAY Demonstrations: Exterior LED Lighting Projects at Princeton University

    Energy Technology Data Exchange (ETDEWEB)

    Davis, Robert G. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Evans, WIlliam E. [Princeton Univ., NJ (United States); Murphy, Arthur [Princeton Univ., NJ (United States); Perrin, Tess [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2015-10-30

    This report focuses on four exterior solid-state lighting projects that have been completed at Princeton since 2008, when the University adopted a comprehensive sustainability plan. Through these initial projects – which include a parking garage, a pedestrian path, and two parking lot installations – the school’s facilities engineering staff learned important lessons about SSL technology and gained experience in dealing with the rapidly changing landscape of lighting manufacturers and their suppliers.

  13. Microhardness of resin composite materials light-cured through fiber reinforced composite.

    NARCIS (Netherlands)

    Fennis, W.M.M.; Ray, N.J.; Creugers, N.H.J.; Kreulen, C.M.

    2009-01-01

    OBJECTIVES: To compare polymerization efficiency of resin composite basing materials when light-cured through resin composite and fiber reinforced composite (FRC) by testing microhardness. METHODS: Simulated indirect restorations were prepared by application of resin composite (Clearfil AP-X) or FRC

  14. Influence of light-curing unit systems on shear bond strength and marginal microleakage of composite resin restorations

    Directory of Open Access Journals (Sweden)

    Juliano Fernandes Sassi

    2008-03-01

    Full Text Available The aim of the present study was to evaluate the influence of different photopolymerization (halogen, halogen soft-start and LED systems on shear bond strength (SBS and marginal microleakage of composite resin restorations. Forty Class V cavities (enamel and dentin margins were prepared for microleakage assessment, and 160 enamel and dentin fragments were prepared for the SBS test, and divided into 4 groups. Kruskal-Wallis and Wilcoxon tests showed statistically significant difference in microleakage between the margins (p 0.05 neither between substrates nor among groups. It was concluded that Soft-Start technique with high intensity end-light influenced negatively the cervical marginal sealing, but the light-curing systems did not influence adhesion.

  15. Smart street lighting : The advantages of LED street lighting and a smart control system in Uppsala municipality

    OpenAIRE

    Sjöberg, Inga; Gidén Hember, Amanda; Wallerström, Carolina

    2017-01-01

    The purpose of this bachelor thesis is to examine how LED street lights and a smart street light control system can reduce the energy consumption, costs and in extension the CO2 equivalents in a geographically delimited area. In 2015 the municipality of Sala installed LED armatures connected to a smart control system in the whole municipality. The smart control system enables for instance adjustment of the light intensity at specific times during the day and a supervision of the street light ...

  16. Life-Cycle Assessment of Energy and Environmental Impacts of LED Lighting Products, Part 3: LED Environmental Testing

    Energy Technology Data Exchange (ETDEWEB)

    Tuenge, Jason R.; Hollomon, Brad; Dillon, Heather E.; Snowden-Swan, Lesley J.

    2013-03-01

    This report covers the third part of a larger U.S. Department of Energy (DOE) project to assess the life-cycle environmental and resource impacts in the manufacturing, transport, use, and disposal of light-emitting diode (LED) lighting products in relation to incumbent lighting technologies. All three reports are available on the DOE website (www.ssl.energy.gov/tech_reports.html). • Part 1: Review of the Life-Cycle Energy Consumption of Incandescent, Compact Fluorescent and LED Lamps; • Part 2: LED Manufacturing and Performance; • Part 3: LED Environmental Testing. Parts 1 and 2 were published in February and June 2012, respectively. The Part 1 report included a summary of the life-cycle assessment (LCA) process and methodology, provided a literature review of more than 25 existing LCA studies of various lamp types, and performed a meta-analysis comparing LED lamps with incandescent and compact fluorescent lamps (CFLs). Drawing from the Part 1 findings, Part 2 performed a more detailed assessment of the LED manufacturing process and used these findings to provide a comparative LCA taking into consideration a wider range of environmental impacts. Both reports concluded that the life-cycle environmental impact of a given lamp is dominated by the energy used during lamp operation—the upstream generation of electricity drives the total environmental footprint of the product. However, a more detailed understanding of end-of-life disposal considerations for LED products has become increasingly important as their installation base has grown. The Part 3 study (reported herein) was undertaken to augment the LCA findings with chemical analysis of a variety of LED, CFL, and incandescent lamps using standard testing procedures. A total of 22 samples, representing 11 different models, were tested to determine whether any of 17 elements were present at levels exceeding California or Federal regulatory thresholds for hazardous waste. Key findings include: • The selected

  17. Demonstration Assessment of LED Roadway Lighting: Philadelphia, PA

    Energy Technology Data Exchange (ETDEWEB)

    Royer, Michael P.; Tuenge, Jason R.; Poplawski, Michael E.

    2012-09-01

    For this demonstration assessment, 10 different groups of LED luminaires were installed at three sites in Philadelphia, PA. Each of the three sites represented a different set of conditions, most importantly with regard to the incumbent HPS luminaires, which were nominally 100 W, 150 W, and 250 W. The performance of each product was evaluated based on manufacturer data, illuminance calculations, field measurements of illuminance, and the subjective impressions of both regular and expert observers.

  18. Efficient and versatile light. LEDs save energy and open up manifold possibilities of design; Effizientes und vielseitiges Licht. LEDs sparen Energie und eroeffnen zahlreiche Designmoeglichkeiten

    Energy Technology Data Exchange (ETDEWEB)

    Fiebig, Michael [OSRAM Opto Semicondutors GmbH, Muenchen (Germany). Bereich Marketing und Business Development

    2010-07-01

    Light bulbs leave the European market step by step. These conventional light sources are too inefficient in the private and conventional sector. There are a lot of alternatives to light bulbs. But no technology will be able to save as much energy as light emitting diodes (LED) in the future. Today, these LEDs meet us in most different applications. Continuously new areas of application are opened up in order to reduce the power requirement clearly for the production of artificial light. Apart from energy conservation diodes also enable untold possibilities. In the future, light can be still more flexibly used owing to LED. LEDs are ideal light sources for planners and designers.

  19. Analysis and Design of Phase Change Thermal Control for Light Emitting Diode (LED) Spacesuit Helmet Lights

    Science.gov (United States)

    Bue, Grant C.; Nguyen, Hiep X.; Keller, John R.

    2010-01-01

    LED Helmet Extravehicular Activity Helmet Interchangeable Portable (LEHIP) lights for the Extravehicular Mobility Unit (EMU) have been built and tested and are currently being used on the International Space Station. A design is presented of the passive thermal control system consisting of a chamber filled with aluminum foam and wax. A thermal math model of LEHIP was built and correlated by test to show that the thermal design maintains electronic components within hot and cold limits for a 7 hour spacewalk in the most extreme EVA average environments, and do not pose a hazard to the crew or to components of the EMU.

  20. Design of asymmetric freeform lens for low glared LED street light with total internal reflection.

    Science.gov (United States)

    Lai, Min-Feng; Chen, Yi-Chian; Anh, Nguyen Doan Quoc; Chen, Tsai-Yu; Ma, Hsin-Yi; Lee, Hsiao-Yi

    2016-01-25

    The study is focused on the asymmetric secondary freeform lens (ASFL) design for creating a low glared light-emitting diode (LED) street light. The lens is mounted on a chip on board (COB) LED as the new LED street light module to perform a non-axial symmetric light intensity distribution. The experimental results show that the street light can work without inclining lamps and reach Chinese National Standards (CNS) and Illuminating Engineering Society of North America (IESNA) standards at the same time.

  1. Improving ?color rendering? of LED lighting for the growth of lettuce

    OpenAIRE

    Han, Tao; Vaganov, Vitaliy; Cao, Shixiu; Li, Qiang; Ling, Lili; Cheng, Xiaoyao; Peng, Lingling; Zhang, Congzhi; Yakovlev, Alexey N.; Zhong, Yang; Tu, Mingjing

    2017-01-01

    Light plays a vital role on the growth and development of plant. On the base of white light with high color rendering to the benefit of human survival and life, we proposed to improve ?color rendering? of LED lighting for accelerating the growth of lettuce. Seven spectral LED lights were adopted to irradiate the lettuces under 150 ?mol?m?2?s?1 for a 16 hd?1 photoperiod. The leaf area and number profiles, plant biomass, and photosynthetic rate under the as-prepared LED light treatments were in...

  2. Enhanced biomass production and lipid accumulation of Picochlorum atomus using light-emitting diodes (LEDs).

    Science.gov (United States)

    Ra, Chae Hun; Kang, Chang-Han; Jung, Jang-Hyun; Jeong, Gwi-Taek; Kim, Sung-Koo

    2016-10-01

    The effects of light-emitting diode (LED) wavelength, light intensity, nitrate concentration, and time of exposure to different LED wavelength stresses in a two-phase culture on lipid production were evaluated in the microalga, Picochlorum atomus. The biomass produced by red LED light was higher than that produced by purple, blue, green, or yellow LED and fluorescent lights from first phase of two-phase culture. The highest lipid production of P. atomus was 50.3% (w/w) with green LED light at 2days of second phase as light stress. Fatty acid analysis of the microalgae showed that palmitic acid (C16:0) and linolenic acid (C18:3) accounted for 84-88% (w/w) of total fatty acids from P. atomus. The two-phase culture of P. atomus is suitable for biofuel production due to higher lipid productivity and favorable fatty acid composition. Copyright © 2016 Elsevier Ltd. All rights reserved.

  3. Spatial layout optimization design of multi-type LEDs lighting source based on photoelectrothermal coupling theory

    Science.gov (United States)

    Xue, Lingyun; Li, Guang; Chen, Qingguang; Rao, Huanle; Xu, Ping

    2018-03-01

    Multiple LED-based spectral synthesis technology has been widely used in the fields of solar simulator, color mixing, and artificial lighting of plant factory and so on. Generally, amounts of LEDs are spatially arranged with compact layout to obtain the high power density output. Mutual thermal spreading among LEDs will produce the coupled thermal effect which will additionally increase the junction temperature of LED. Affected by the Photoelectric thermal coupling effect of LED, the spectrum of LED will shift and luminous efficiency will decrease. Correspondingly, the spectral synthesis result will mismatch. Therefore, thermal management of LED spatial layout plays an important role for multi-LEDs light source system. In the paper, the thermal dissipation network topology model considering the mutual thermal spreading effect among the LEDs is proposed for multi-LEDs system with various types of power. The junction temperature increment cased by the thermal coupling has the great relation with the spatial arrangement. To minimize the thermal coupling effect, an optimized method of LED spatial layout for the specific light source structure is presented and analyzed. The results showed that layout of LED with high-power are arranged in the corner and low-power in the center. Finally, according to this method, it is convenient to determine the spatial layout of LEDs in a system having any kind of light source structure, and has the advantages of being universally applicable to facilitate adjustment.

  4. Laser-light backscattering response to water content and proteolysis in dry-cured ham

    DEFF Research Database (Denmark)

    Fulladosa, E.; Rubio-Celorio, M.; Skytte, Jacob Lercke

    2017-01-01

    Laser backscattering imaging (LBI) is a low-cost technology proposed to determine non-invasively composition and microstructural characteristics of agro food and dairy products. The aim of this work was to define the effect of different acquisition conditions (wavelength, object distance and angle......-cured ham was also evaluated. Results showed that a red laser (635 nm) is more convenient than a green laser (532 nm) to analyse dry-cured ham but no preferable angle or object distance to evaluate dryness or proteolysis was found. Nevertheless, light scattering parameters were modified depending...

  5. Improving "color rendering" of LED lighting for the growth of lettuce.

    Science.gov (United States)

    Han, Tao; Vaganov, Vitaliy; Cao, Shixiu; Li, Qiang; Ling, Lili; Cheng, Xiaoyao; Peng, Lingling; Zhang, Congzhi; Yakovlev, Alexey N; Zhong, Yang; Tu, Mingjing

    2017-04-03

    Light plays a vital role on the growth and development of plant. On the base of white light with high color rendering to the benefit of human survival and life, we proposed to improve "color rendering" of LED lighting for accelerating the growth of lettuce. Seven spectral LED lights were adopted to irradiate the lettuces under 150 μmol·m -2 ·s -1 for a 16 hd -1 photoperiod. The leaf area and number profiles, plant biomass, and photosynthetic rate under the as-prepared LED light treatments were investigated. We let the absorption spectrum of fresh leaf be the emission spectrum of ideal light and then evaluate the "color rendering" of as-prepared LED lights by the Pearson product-moment correlation coefficient and CIE chromaticity coordinates. Under the irradiation of red-yellow-blue light with high correlation coefficient of 0.587, the dry weights and leaf growth rate are 2-3 times as high as the sharp red-blue light. The optimized LED light for lettuce growth can be presumed to be limited to the angle (about 75°) between the vectors passed through the ideal light in the CIE chromaticity coordinates. These findings open up a new idea to assess and find the optimized LED light for plant growth.

  6. Improving “color rendering” of LED lighting for the growth of lettuce

    Science.gov (United States)

    Han, Tao; Vaganov, Vitaliy; Cao, Shixiu; Li, Qiang; Ling, Lili; Cheng, Xiaoyao; Peng, Lingling; Zhang, Congzhi; Yakovlev, Alexey N.; Zhong, Yang; Tu, Mingjing

    2017-04-01

    Light plays a vital role on the growth and development of plant. On the base of white light with high color rendering to the benefit of human survival and life, we proposed to improve “color rendering” of LED lighting for accelerating the growth of lettuce. Seven spectral LED lights were adopted to irradiate the lettuces under 150 μmol·m-2·s-1 for a 16 hd-1 photoperiod. The leaf area and number profiles, plant biomass, and photosynthetic rate under the as-prepared LED light treatments were investigated. We let the absorption spectrum of fresh leaf be the emission spectrum of ideal light and then evaluate the “color rendering” of as-prepared LED lights by the Pearson product-moment correlation coefficient and CIE chromaticity coordinates. Under the irradiation of red-yellow-blue light with high correlation coefficient of 0.587, the dry weights and leaf growth rate are 2-3 times as high as the sharp red-blue light. The optimized LED light for lettuce growth can be presumed to be limited to the angle (about 75°) between the vectors passed through the ideal light in the CIE chromaticity coordinates. These findings open up a new idea to assess and find the optimized LED light for plant growth.

  7. Synergetic Effect between Lighting Efficiency Enhancement and Building Energy Reduction Using Alternative Thermal Operating System of Indoor LED Lighting

    Directory of Open Access Journals (Sweden)

    Byung-Lip Ahn

    2015-08-01

    Full Text Available We investigated the synergetic effect between light-emitting diode (LED lighting efficiency and building energy savings in heating and cooling using an alternative thermal operating system (ATOS of indoor LED lighting integrated with the ventilation system of a building as an active cooling device. The heat generated from LED lighting and the indoor lighting illuminance were experimentally determined. The indoor heat gains in cooling and heating periods were determined using measurement data; the annual energy savings of an office building in heating and cooling were calculated through simulation. The LED lighting illuminance increased by approximately 40% and the lighting contribution for indoor heat gain was 7.8% in summer, while 69.8% in winter with the ATOS. Consequently, the annual total energy use of the office building could be reduced by 5.9%; the energy use in cooling and heating was reduced by 18.4% and 3.3%, respectively.

  8. Electronic homogeneity of nanowire heterostructure Light Emitting Diodes (LEDs)

    Science.gov (United States)

    Selcu, Camelia; May, Brelon J.; Sarwar, A. T. M. Golam; Myers, Roberto C.

    In addition to low defect densities and great tunability bandgap within a single heterostructure, the possibility of growing (Al, In,_) GaN nanowire heterostructure LEDs on different substrates while maintaining their high electronic and optical properties makes them very attractive. We investigated the electronic homogeneity of the (Al, In,_) GaN nanowire ensemble by acquiring current maps at certain applied biases using conductive AFM. By taken IVs on individual nanowires, we found that different wires have different turn on voltages and that some of the nanowires degrade due to the applied bias.

  9. Development of LED light sources and lamps. Final report; Slutrapport for PSO 337-068. Udvikling af LED lyskilder og lamper

    Energy Technology Data Exchange (ETDEWEB)

    Dam-Hansen, C.; Petersen, Paul Michael; Thestrup, B.; Scharling Holm, J.; Munkgaard Andersen, J.; Falleboe, H.; Olsen, Jesper; Flindt, C.

    2007-04-15

    This report is the final and concluding report on the research and development project 'Development of LED light sources and lamps' PSO no. 337-068 supported by Dansk Energi - Net. The project was a collaboration between Risoe National laboratory, Louis Poulsen Lighting, Dong Energy, Laboratoriet Lys & Syn and RGB Lamps. The objective of this project was to pave the way for replacement of incandescent- and halogen lighting by LED lightning through development of prototypes for new types of LED products: light sources and lamps. The report summarizes and describes the main results of the project, which are: 1) a new LED light source with an efficacy of 51 lm/W and a CRI index of 92 that can replace an incandescent bulb. 2) two LED pendants/lamps, a LED table lamp and a chair with LED lighting developed by designers and researchers. 3) LED seminar and two exhibitions of the newly developed LED products and user test by questionnaires. 4) A new startup company 'Morfoso'. 5) Developed course on light and LED technology for designers. 6) A new LED light laboratory for test and characterization of LED components and LED light sources and lamps. (au)

  10. Power density of various light curing units through resin inlays with modified layer thickness

    Directory of Open Access Journals (Sweden)

    Sung-Ok Hong

    2012-08-01

    Full Text Available Objectives The purpose of this study was to enhance curing light penetration through resin inlays by modifying the thicknesses of the dentin, enamel, and translucent layers. Materials and Methods To investigate the layer dominantly affecting the power density of light curing units, resin wafers of each layer with 0.5 mm thickness were prepared and power density through resin wafers was measured with a dental radiometer (Cure Rite, Kerr. The dentin layer, which had the dominant effect on power density reduction, was decreased in thickness from 0.5 to 0.1 mm while thickness of the enamel layer was kept unchanged at 0.5 mm and thickness of the translucent layer was increased from 0.5 to 0.9 mm and vice versa, in order to maintain the total thickness of 1.5 mm of the resin inlay. Power density of various light curing units through resin inlays was measured. Results Power density measured through 0.5 mm resin wafers decreased more significantly with the dentin layer than with the enamel and translucent layers (p < 0.05. Power density through 1.5 mm resin inlays increased when the dentin layer thickness was reduced and the enamel or translucent layer thickness was increased. The highest power density was recorded with dentin layer thickness of 0.1 mm and increased translucent layer thickness in all light curing units. Conclusions To enhance the power density through resin inlays, reducing the dentin layer thickness and increasing the translucent layer thickness would be recommendable when fabricating resin inlays.

  11. Transmission of Curing Light through Moist, Air-Dried, and EDTA Treated Dentine and Enamel.

    Science.gov (United States)

    Uusitalo, E; Varrela, J; Lassila, L; Vallittu, P K

    2016-01-01

    Objective. This study measured light transmission through enamel and dentin and the effect of exposed dentinal tubules to light propagation. Methods. Light attenuation through enamel and dentin layers of various thicknesses (1 mm, 2 mm, 3 mm, and 4 mm) was measured using specimens that were (1) moist and (2) air-dried (n = 5). Measurements were repeated after the specimens were treated with EDTA. Specimens were transilluminated with a light curing unit (maximum power output 1869 mW/cm(2)), and the mean irradiance power of transmitting light was measured. The transmission of light through teeth was studied using 10 extracted intact human incisors and premolars. Results. Transmitted light irradiance through 1 mm thick moist discs was 500 mW/cm(2) for enamel and 398 mW/cm(2) for dentin (p Beer-Lambert's law.

  12. A white–cyan-red LED system for low correlated colour temperature lighting

    DEFF Research Database (Denmark)

    Chakrabarti, Maumita; Thorseth, Anders; Corell, Dennis Dan

    2015-01-01

    A white LED complemented by cyan and red LEDs is a good candidate for achieving high colour rendering at low correlated colour temperatures. This is usually very difficult with commercially available white LEDs. In addition, the system is able to replace incandescent lighting in many applications......; for example, the lighting for museum display cases. To investigate and optimize the colour and light distribution properties, both spectral and geometrical modelling are used. Mapping of the possible combinations of LEDs is used to locate the optimal solutions within the colour gamut, with emphasis...

  13. GATEWAY Demonstrations: Philadelphia International Airport Apron Lighting: LED System Performance in a Trial Installation

    Energy Technology Data Exchange (ETDEWEB)

    Davis, Robert G. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Wilkerson, Andrea M. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2015-10-30

    This report documents a trial installation of LED apron lighting that replaced the existing high-pressure sodium luminaires at Philadelphia International Airport. Such high-mast applications remain challenging for LED technology, and the lessons learned from this project may help facility managers and LED product manufacturers better meet those challenges.

  14. A high-performance stand-alone solar PV power system for LED lighting

    KAUST Repository

    Huang, B. J.

    2010-06-01

    The present study developed a high-performance solar PV power technology for the LED lighting of a solar home system. The nMPPO (near-Maximum-Power- Point- Operation) design is employed in system design to eliminate MPPT. A feedback control system using pulse width modulation (PWM) technique was developed for battery charging control which can increase the charging capacity by 78%. For high-efficiency lighting, the LED is directly driven by battery using a PWM discharge control to eliminate a DC/DC converter. Two solar-powered LED lighting systems (50W and 100W LED) were built. The long-term outdoor tests have shown that the loss of load probability for full-night lighting requirement is zero for 50W LED and 3.6% for 100W LED. © 2010 IEEE.

  15. Life-Cycle Assessment of Energy and Environmental Impacts of LED Lighting Products Part 2: LED Manufacturing and Performance

    Energy Technology Data Exchange (ETDEWEB)

    Scholand, Michael; Dillon, Heather E.

    2012-05-01

    Part 2 of the project (this report) uses the conclusions from Part 1 as a point of departure to focus on two objectives: producing a more detailed and conservative assessment of the manufacturing process and providing a comparative LCA with other lighting products based on the improved manufacturing analysis and taking into consideration a wider range of environmental impacts. In this study, we first analyzed the manufacturing process for a white-light LED (based on a sapphire-substrate, blue-light, gallium-nitride LED pumping a yellow phosphor), to understand the impacts of the manufacturing process. We then conducted a comparative LCA, looking at the impacts associated with the Philips Master LEDbulb and comparing those to a CFL and an incandescent lamp. The comparison took into account the Philips Master LEDbulb as it is now in 2012 and then projected forward what it might be in 2017, accounting for some of the anticipated improvements in LED manufacturing, performance and driver electronics.

  16. Blue light emitting diodes (LEDs) as an energy source in Chlorella fusca and Synechococcus nidulans cultures.

    Science.gov (United States)

    Duarte, Jessica Hartwig; Costa, Jorge Alberto Vieira

    2018-01-01

    LEDs have narrow wavelength bands, which can influence microalgae biomass. This study pioneers the evaluation of blue LEDs as an energy source in Chlorella fusca and Synechococcus nidulans cultures. Blue LEDs increased the specific growth rate in Synechococcus nidulans LEB 115 cultures by 80% compared to the standard light used in indoor cultivations. Moreover, blue LEDs also induced lipid accumulation in Chlorella fusca LEB 111 cells, yielding concentrations of this bioproduct of up to 23% (ww -1 ). The chlorophylls and carotenoids were photostimulated proportionally to the LED light intensity. When the intensity of the blue LEDs was increased from 50 to 150μmolm -2 s -1 , the biomass accumulated up to 4.5 and 2.4 times more chlorophylls and carotenoids, respectively. The potential of blue LEDs as an alternative environmentally friendly light source to stimulate biomass and metabolite production for different purposes was demonstrated. Copyright © 2017 Elsevier Ltd. All rights reserved.

  17. The use of light-emitting diodes (LED in commercial layer production

    Directory of Open Access Journals (Sweden)

    R Borille

    2013-06-01

    Full Text Available Artificial lighting is one of the most powerful management tools available to commercial layer producers. Artificial light allows anticipating or delaying the beginning of lay, improving egg production, and optimizing feed efficiency. This study aimed at comparing the performance of commercial layers submitted to lighting using different LED colors or conventional incandescent lamps. The study was carried out in a layer house divided in isolated environments in order to prevent any influenced from the neighboring treatments. In total, 360 Isa Brown layers, with an initial age of 56 weeks, were used. The following light sources were used: blue LED, yellow LED, green LED, red LED, white LED, and 40W incandescent light. Birds in all treatment were submitted to a 17-h continuous lighting program, and were fed a corn and soybean meal-based diet. A completely randomized experimental design with subplots was applied, with 24 treatments (six light sources and four periods of three replicates. Egg production (% was significantly different (p0.05 by light source. It was concluded that the replacement of incandescent light bulbs by white and red LEDs does not cause any negative effect on the egg production of commercial layers.

  18. Design and Analysis of an Underwater White LED Fish-Attracting Lamp and its Light Propagation

    Directory of Open Access Journals (Sweden)

    Sheng Chih Shen

    2013-03-01

    Full Text Available Light emitting diodes (LED are a new source for replacing traditional light sources including under water illumination. As traditional underwater light sources operate under a radiative transfer model, the luminous intensity is dispersed evenly at each emission angle, with the scattering factors included in the attenuation coefficient. By contrast, LED light sources are characterized by being highly directional, causing underwater luminous energy to vary with different emission angles. Thus, the traditional theory of underwater optical transfer becomes inapplicable when an underwater LED lighting module is designed. Therefore, to construct an underwater transfer model for LED light sources, this study employed the average cosine of the underwater light field, the method for light scattering probability, the LED luminous intensity distribution curve (LIDC and axial luminous intensity. Afterwards, an underwater LED fish-attracting lamp was designed. Experimental results showed that, compared with the simulation values, the luminous intensity of the underwater LED lighting module at all emission angles had a percentage error of less than 10%.

  19. Prototype of a new tip developed to be coupled to dental light-curing units for optimizing bonding of orthodontic brackets and accessories.

    Science.gov (United States)

    Mota Júnior, Sergio Luiz; Campos, Márcio José da Silva; Gravina, Marco Abdo; Fraga, Marcelo Reis; Vitral, Robert Willer Farinazzo

    2013-01-01

    Development of a new device to be coupled to light-curing units for bonding orthodontic brackets and accessories, and test its efficacy in an in vitro mechanical trial. The inner surface of the device is mirrored and is based on physical concepts of light refraction and reflection. The main advantage of such device is the reduced clinical time needed for bonding and the low possibility of contamination during the process. One hundred and twenty specimens were used for testing the shear bond strength of brackets bonded with the device. The Adhesive Remnant Index (ARI) was also determined. The sample was divided into 2 groups. In group 1 a halogen light-curing unit was used while in group 2 a led light-curing unit was used. Each group was then subdivided. In subgroups H1 and L1, a conventional light guide rod was used while in subgroups H2 and L2 bonding was performed with the mirrored device coupled to the tip of the guide light rod. The values obtained for the shear bond strength and the ARI in the subgroups were compared. Results showed that there was no statistically significant difference for the shear strength (p > 0.05) and the ARI (p > 0.05) between the subgroups. The tests of mechanical trials and the ARI analysis showed that the new device fulfilled the requirements for bonding orthodontic accessories, and that the time for bonding was reduced to half, being necessary only one light exposure.

  20. Determining the dimensional stability, fracture toughness and flexural strength of light-cured acrylic resin custom tray material.

    Science.gov (United States)

    Khan, S B; Geerts, G

    2009-06-01

    Light-cured acrylic resin custom tray material is used in commercial dental laboratories but little evidence-based scientific information on its physical properties is available. This study investigates the dimensional stability of light-cured acrylic resin custom tray material and compares its fracture toughness and flexural strength to a chemically-cured acrylic material. For dimensional stability, 20 light-cured specimens were fabricated and measured 3 times at regular time intervals over 48 hours. Mean shrinkage was calculated for each time interval and the mean values were compared to the standard using the Wilcoxon Rank Sum test. A p-value of materials with a single-edge notch were subjected to a compressive load using the 3-point bending technique. For flexural strength, 1 group (n=20) of each material was subjected to a compressive load using 3-point bending. The highest load before failure was used to calculate the fracture toughness and flexural strength. Differences in fracture toughness and flexural strength values between the 2 groups were compared using ANOVA testing. A p-value of 0.05). The fracture toughness and flexural strength were significantly higher for the light-cured material. Trays made from light-cured acrylic resin can be used immediately following polymerization. The light-cured material is more resistant to bending and crack propagation than the chemically-cured type.

  1. Comparative effectiveness of light emitting diodes (LEDs) and Lasers in near infrared photoimmunotherapy

    Science.gov (United States)

    Sato, Kazuhide; Watanabe, Rira; Hanaoka, Hirofumi; Nakajima, Takahito; Choyke, Peter L.; Kobayashi, Hisataka

    2016-01-01

    Near infrared photoimmunotherapy (NIR-PIT) is a new cancer treatment that combines the specificity of antibodies for targeting tumors with the toxicity induced by photosensitizers after exposure to near infrared (NIR) light. Herein we compare two NIR-light sources; light emitting diodes (LEDs) and Lasers, for their effectiveness in NIR-PIT. A photosensitizer, IRDye-700DX, conjugated to panitumumab (pan-IR700), was incubated with EGFR-expressing A431 and MDA-MB-468-luc cells. NIR-light was provided by LEDs or Lasers at the same light dose. Laser-light produced more cytotoxicity and greater reductions in IR700-fluorescence intensity than LED-light. Laser-light also produced more cytotoxicity in vivo in both cell lines. Assessment of super-enhanced permeability and retention (SUPR) effects were stronger with Laser than LED. These results suggest that Laser-light produced significantly more cytotoxic effects compared to LEDs. Although LED is less expensive, Laser-light produces superior results in NIR-PIT. PMID:26885688

  2. Effect of LED light on seeds of Capsicum annuum L. var. serrano

    Directory of Open Access Journals (Sweden)

    Alejandra María Moreno-Jiménez

    2017-11-01

    Full Text Available Serrano pepper (Capsicum annuum L. is a crop of economic, nutritional and medicinal importance; so it is necessary to increase its production and improve its characteristics. The objective of this research was to evaluate the stimulatory effect of light emitting diodes (LEDs on serrano pepper seedlings. Germination percentage, stem length, leaf width, leaf length, number of leaves, total chlorophyll content and carotenoid content were analyzed. The seeds were exposed to white, blue and red LED light, using fluorescent light as a control and a photoperiod of 11/13 hours. Once germinated, the seedlings continued with exposure to light for 30 days. After the laboratory conditions, the seedlings were transferred to a greenhouse for 60 days. The results show that there were no significant differences between LED light treatments on seed germination. The variables stem length, leaf width and leaf length, were favored with red light. Blue and red LEDs highlighted by increasing the number of leaves. Seedlings treated with blue light showed the highest content of photosynthetic pigments (chlorophyll= 0.84 mg g-1, carotenoid= 0.12 mg g-1. In conclusion, the red LED light is effective for the growth of serrano pepper seedlings, while the production of photosynthetic pigments was favored by blue LED light.   Keywords: peppers, light-emitting diodes, germination, growth, photosynthetic pigments

  3. Comparative effectiveness of light emitting diodes (LEDs) and Lasers in near infrared photoimmunotherapy.

    Science.gov (United States)

    Sato, Kazuhide; Watanabe, Rira; Hanaoka, Hirofumi; Nakajima, Takahito; Choyke, Peter L; Kobayashi, Hisataka

    2016-03-22

    Near infrared photoimmunotherapy (NIR-PIT) is a new cancer treatment that combines the specificity of antibodies for targeting tumors with the toxicity induced by photosensitizers after exposure to near infrared (NIR) light. Herein we compare two NIR-light sources; light emitting diodes (LEDs) and Lasers, for their effectiveness in NIR-PIT. A photosensitizer, IRDye-700DX, conjugated to panitumumab (pan-IR700), was incubated with EGFR-expressing A431 and MDA-MB-468-luc cells. NIR-light was provided by LEDs or Lasers at the same light dose. Laser-light produced more cytotoxicity and greater reductions in IR700-fluorescence intensity than LED-light. Laser-light also produced more cytotoxicity in vivo in both cell lines. Assessment of super-enhanced permeability and retention (SUPR) effects were stronger with Laser than LED. These results suggest that Laser-light produced significantly more cytotoxic effects compared to LEDs. Although LED is less expensive, Laser-light produces superior results in NIR-PIT.

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

    Science.gov (United States)

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

    2001-01-01

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

  5. Influence of light source and extended time of curing on microhardness and degree of conversion of different regions of a nanofilled composite resin.

    Science.gov (United States)

    Lima, Adriano Fonseca; de Andrade, Kamila Menezes Guedes; da Cruz Alves, Louise Esther; Soares, Giulliana Panfiglio; Marchi, Giselle Maria; Aguiar, Flávio Henrique Baggio; Peris, Alessandra Rezende; Mitsui, Fábio Hiroyuki Ogata

    2012-04-01

    The aim of this study was to evaluate the effects of different light sources and curing time on the degree of conversion and microhardness of two surfaces within a nanofilled composite resin. Four experimental groups (n=10) were formed in accordance with the light source (quartz-tungsten halogen (QTH - 600mW/cm(2)), or light-emitting-diode (LED - 800mW/cm(2))) and the time of curing (20 s or 40 s). The specimens were prepared with a circular mould (5 mm ∅ and 2 mm thick), according to the respective protocol, and the Knoop microhardness and degree of conversion was measured at the top and the base of the specimens. The degree of conversion was evaluated by the Fourier transform infrared spectrometer (FTIR). The results were analyzed by ANOVA two-way repeated measures and Tukey's test (α=,05). Both the degree of conversion and microhardness were higher at the top than at the bottom of the specimens. The QTH light source presented better values on the degree of conversion evaluation, but this result was not observed in the microhardness evaluation. Although forty seconds of curing promotes an increased level of microhardness, it did not influence the degree of conversion. It could be concluded that increasing the time of curing to 40 s promotes an increase in microhardness, but it does not influence the degree of conversion of a nanofilled composite resin. QTH promote better monomeric conversion; however, the microhardness values are similar to LED curing. For all situations tested, the bottom of the specimens presented lower results than the top.

  6. A survey of power density of light-curing units used in private dental offices in Changchun City, China.

    Science.gov (United States)

    Hao, Xinqing; Luo, Meng; Wu, Jian; Zhu, Song

    2015-02-01

    This study investigated power density and relevant information related to light-curing units used in private dental offices in Changchun City, China. The power density of 196 light-curing units used in private dental offices in Changchun City was measured using a simple random sampling method. Relevant information included the brand, type, years of operation, frequency of use, model numbers and types of light guide, resin buildup on the light guides, damage caused by the light guides, required maintenance of the curing lights, and ratio of the unit and chair number. There were 132 quartz tungsten halogen (QTH) units and 64 light-emitting diode units. The power density range was defined as 0-1,730 mW/cm(2). The mean power density was 453.1 mW/cm(2). The mean years of operation of the light-curing units were 3.96. The majority of dentists never tested the power density of the light-curing units and a considerable number of light guide surfaces showed resin buildup and damage. In Changchun City, the majority of light-curing units were QTH. Some units needed to be replaced due to aging. The majority of dentists were not aware that the light-curing units require periodic testing and maintenance. The data herein indicate the importance of periodic testing of the power density of light-curing units and timely replacement of the components and then guarantee the quality of medical services and their benefits to patients.

  7. Light Transmission of Novel CAD/CAM Materials and Their Influence on the Degree of Conversion of a Dual-curing Resin Cement.

    Science.gov (United States)

    Egilmez, Ferhan; Ergun, Gulfem; Cekic-Nagas, Isil; Vallittu, Pekka K; Lassila, Lippo V J

    To evaluate the light transmission characteristics of different types, shades, and thicknesses of novel CAD/CAM materials and their effect on the degree of conversion (DC) of a dual-curing resin cement. Square specimens (12 × 12 mm2) of three CAD/CAM materials - GC Cerasmart, Lava Ultimate, Vita Enamic - of different thicknesses (1.00, 1.50, and 2.00 mm, n = 5 per thickness) were irradiated with an LED unit. The amount of transmitted light was quantified. Thereafter, the DC% of the dual-curing resin cement (RelyX Ultimate) was recorded after 15 min using Fourier transform infrared spectroscopy. Statistical analysis was performed using two-way ANOVA followed by the Tukey's HSD post-hoc test at a significance level of p light irradiation (p  0.05). Conversely, material thickness significantly affected light transmission (p light irradiation; p = 0.637 for DC). Linear regression analysis showed a correlation between delivered energy and DC% results of the Vita Enamic (R² = 0.4169, p light transmission in 2-mm-thick specimens of all CAD/CAM materials indicates that proper curing of the cement beneath CAD/CAM materials should be ensured.

  8. [Experimental study on the reinforced effect of light curing composite resins used for crowns and bridges].

    Science.gov (United States)

    Sun, J; Zhang, J Z

    2001-03-01

    To evaluate the reinforced effect of the light curing composite resins used for crowns and bridges. Three light curing composite resins which were used for crowns and bridges were chosen, and three polyester fiber sieves and three stainless steel sieves in different mesh were used as the additional reinforced materials. Compressive strength and three point flexural strength of test bars made of those materials were evaluated. The reinforced bridges with special fibers were used as control groups. (1)There was significant increase in the stainless steel sieves groups. Nevertheless, there was some decrease after use of the polyester fibers as the additional reinforced material. (2)The increase of the reinforced crowns was especially obvious. (3)Among the three resins, the property of Targis was better than that of Arglass and Solidex. The properties of the whole composite material were closely correlated with the additional reinforced materials, the resistance to compression of the sieves are better than its resistance to bend.

  9. MudGet: Reproduction of the desired lighting environment using a smart-LED

    Directory of Open Access Journals (Sweden)

    Yong Hwi Kim

    2017-07-01

    Full Text Available With the emergence of smart LEDs, lighting based interior design is becoming popular. However, most of the smart LED-based lighting systems rely on expert-human intervention to create a desired atmosphere. For convenience, commercial lighting systems offer a number of options but their usability is fairly restricted. Therefore, an intuitive interface is required for novice users to generate the desired lighting environment. In this paper, we have developed a software, named MudGet, which automatically extracts the light mood from a digital image and controls the LED lamps to reproduce a desired lighting effect according to the extracted light mood. In our method, the light mood is regarded as a set of the representative colors of the digital image. The representative colors are extracted by utilizing K-means clustering algorithm. The dimming parameters are set for which each of the LED lamps create the lighting environment with the mood extracted by the software. To evaluate the feasibility of mood reproduction qualitatively, the degree of similarity between the light mood in the digital image and the reproduced result using LEDs is evaluated by a user study under a miniaturized experimental set. We observe that users can easily produce a desired atmosphere through the proposed MudGet software.

  10. A new method to manipulate broiler chicken growth and metabolism: Response to mixed LED light system.

    Science.gov (United States)

    Yang, Yefeng; Yu, Yonghua; Pan, Jinming; Ying, Yibin; Zhou, Hong

    2016-05-12

    Present study introduced a new method to manipulate broiler chicken growth and metabolism by mixing the growth-advantage LED. We found that the green/blue LED mixed light system (G-B and G × B) have the similar stimulatory effect on chick body weight with single green light and single blue light (G and B), compared with normal artificial light (P = 0.028). Moreover, the percentage of carcass was significantly greater in the mixed light (G × B) when compared with the single light (P = 0.003). Synchronized with body weight, the mixed light (G-B and G × B) had a significant improved influence on the feed conversion of birds compared with normal light (P = 0.002). A significant improvement in feed conversion were found in mixed light (G × B) compared with single LED light (P = 0.037). G group resulted in a greater high-density lipoprotein cholesterol level than B group (P = 0.002), whereas B group resulted in a greater low-density lipoprotein cholesterol level than G group (P = 0.017). The mixed light significantly increased the birds' glucose level in comparison with the single light (P = 0.003). This study might establish an effective strategy for maximizing growth of chickens by mixed LED technology.

  11. Monolithically Integrated Light Feedback Control Circuit for Blue/UV LED Smart Package

    NARCIS (Netherlands)

    Koladouz Esfahani, Z.; Tohidian, M.; van Zeijl, H.W.; Kolahdouz, Mohammadreza; Zhang, G.Q.

    2017-01-01

    Given the performance decay of high-power light-emitting diode (LED) chips over time and package condition changes, having a reliable output light for sensitive applications is a point of concern. In this study, a light feedback control circuit, including blue-selective photodiodes, for

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

    Science.gov (United States)

    Ebbesen, Finn; Vandborg, Pernille K; Madsen, Poul H; Trydal, Torleif; Jakobsen, Lasse H; Vreman, Hendrik J

    2016-02-01

    Blue light with peak emission around 460 nm is the preferred treatment of neonatal hyperbilirubinemia. However, studies using fluorescent light tubes have suggested that turquoise light with peak emission at 490 nm may be more efficient. At present, the predominant light source for phototherapy is light emitting diodes (LEDs). Hence, the aim of this study was to compare the bilirubin-reducing effect in jaundiced neonates treated either with turquoise or with blue LED light with peak emission at 497 or 459 nm, respectively, with equal irradiance on the infants. Infants with gestational age ≥33 wk and uncomplicated hyperbilirubinemia were randomized to either turquoise or blue LED light and were treated for 24 h. The mean irradiance footprint at skin level was 5.2 × 10(15) and 5.1 × 10(15) photons/cm(2)/s, respectively. Forty-six infants received turquoise light and 45 received blue light. The median (95% confidence interval) decrease of total serum bilirubin was 35.3% (32.5; 37.3) and 33.1% (27.1; 36.8) for infants treated with turquoise and blue lights, respectively. The difference was nonsignificant (P = 0.53). The decrease was positively correlated to postnatal age and negatively to birth weight. Using LED light of equal irradiance, turquoise and blue lights had equal bilirubin-reducing effect on hyperbilirubinemia of neonates.

  13. Analysis of Shade Matching in Natural Dentitions Using Intraoral Digital Spectrophotometer in LED and Filtered LED Light Sources.

    Science.gov (United States)

    Chitrarsu, Vijai Krishnan; Chidambaranathan, Ahila Singaravel; Balasubramaniam, Muthukumar

    2017-10-31

    To evaluate the shade matching capabilities in natural dentitions using Vita Toothguide 3D-Master and an intraoral digital spectrophotometer (Vita Easyshade Advance 4.0) in various light sources. Participants between 20 and 40 years old with natural, unrestored right maxillary central incisors, no history of bleaching, orthodontic treatment, or malocclusion and no rotations were included. According to their shades, subjects were randomly selected and grouped into A1, A2, and A3. A total of 100 participants (50 male and 50 female) in each group were chosen for this study. Shade selection was made between 10 am and 2 pm for all light sources. The same examiner selected the shade of natural teeth with Vita Toothguide 3D-Master under natural light within 2 minutes. Once the Vita Toothguide 3D-Masterwas matched with the maxillary right central incisor, the L*, a*, and b* values, chroma, and hue were recorded with Vita Easyshade Advance 4.0 by placing it on the shade tab under the same light source. The values were statistically analyzed using one-way ANOVA and Tukey's HSD post hoc test with SPSS v22.0 software. The mean ∆E* ab values for shades A1, A2, and A3 for groups 1, 2, and 3 were statistically significantly different from each other (p spectrophotometer showed statistically significant differences in shade matching compared to Vita Toothguide 3D-Master. Incandescent light showed more accurate shade matching than the filtered LED, LED, and daylight. © 2017 by the American College of Prosthodontists.

  14. Effect of thickness of indirect restoration and distance from the light-curing unit tip on the hardness of a dual-cured resin cement.

    Science.gov (United States)

    de Paula, Andréia Bolzan; Tango, Rubens Nisie; Sinhoreti, Mário Alexandre Coelho; Alves, Marcelo Corrêa; Puppin-Rontani, Regina M

    2010-01-01

    This study evaluated the Knoop hardness and polymerization depth of a dual-cured resin cement, light-activated at different distances through different thicknesses of composite resin. One bovine incisor was embedded in resin and its buccal surface was flattened. Dentin was covered with PVC film where a mold (0.8-mm-thick and 5 mm diameter) was filled with cement and covered with another PVC film. Light curing (40 s) was carried out through resin discs (2, 3, 4 or 5 mm) with a halogen light positioned 0, 1, 2 or 3 mm from the resin surface. After storage, specimens were sectioned for hardness measurements (top, center, and bottom). Data were subjected to split-plot ANOVA and Tukey's test (alpha=0.05). The increase in resin disc thickness decreased cement hardness. The increase in the distance of the light-curing tip decreased hardness at the top region. Specimens showed the lowest hardness values at the bottom, and the highest at the center. Resin cement hardness was influenced by the thickness of the indirect restoration and by the distance between the light-curing unit tip and the resin cement surface.

  15. Light-Curing Units: A Review of What We Need to Know.

    Science.gov (United States)

    Price, R B; Ferracane, J L; Shortall, A C

    2015-09-01

    For improved interstudy reproducibility, reduced risk of premature failures, and ultimately better patient care, researchers and dentists need to know how to accurately characterize the electromagnetic radiation (light) they are delivering to the resins they are using. The output from a light-curing unit (LCU) is commonly characterized by its irradiance. If this value is measured at the light tip, it describes the radiant exitance from the surface of the light tip, and not the irradiance received by the specimen. The value quoted also reflects only an averaged value over the total measurement area and does not represent the irradiance that the resin specimen is receiving locally or at a different moment in time. Recent evidence has reported that the spectral emission and radiant exitance beam profiles from LCUs can be highly inhomogeneous. This can cause nonuniform temperature changes and uneven photopolymerization within the resin restoration. The spectral radiant power can be very different between different brands of LCUs, and the use of irradiance values derived from dental radiometers to describe the output from an LCU for research purposes is discouraged. Manufacturers should provide more information about the light output from the LCU and the absorption spectrum of their resin-based composite (RBC). Ideally, future assessments and research publications should include the following information about the curing light: 1) radiant power output throughout the exposure cycle and the spectral radiant power as a function of wavelength, 2) analysis of the light beam profile and spectral emission across the light beam, and 3) measurement and reporting of the light the RBC specimen received as well as the output measured at the light tip. © International & American Associations for Dental Research 2015.

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

    Science.gov (United States)

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

    2016-04-01

    Light-induced oxidation of milk has been well studied. Exposure of milk to UV light facilitates the oxidation of fats to aldehydes, and the degradation of sulfur-containing amino acids, both of which contribute to off-flavors. In addition, vitamin A and riboflavin are easily degraded by UV light. These reactions occur rapidly and are exacerbated by bright fluorescent lights in retail dairy cases. The invention of white light-emitting diodes (LED) may provide a solution to this oxidation problem. In this study, fresh milk containing 1% fat and fortified with vitamin A and riboflavin was exposed to LED at 4,000 lx, or fluorescent light at 2,200 lx for 24 h. Milk samples exposed to LED or fluorescent light, as well as milk protected from light, were analyzed by a consumer acceptance panel, and a trained flavor panel. In addition, vitamin A, riboflavin, and the production of volatile compounds were quantified. Exposure to light resulted in a reduction of cooked/sweet, milkfat, and sweet flavors and increased the intensity of butterscotch, cardboard, and astringency. In general, exposure to fluorescent light resulted in greater changes in the milk than exposure to LED even though the LED was at higher intensity. Consumers were able detect off-flavors in milk exposed to fluorescent light after 12 h and LED after 24 h of exposure. The riboflavin and vitamin A content was reduced by exposure to fluorescent light, whereas there was no significant reduction caused by LED compared with the non-light-exposed control. Production of hexanal, heptanal, 2-heptanal, octanal, 2-octanal nonanal, dimethyl sulfide, and caproic acid vinyl ester from the light-induced degradation of fats was significantly higher with fluorescent than LED. Production of these compounds was significantly higher with both light treatments than in the control milk. This study indicates that LED is less destructive to milk than fluorescent light. Copyright © 2016 American Dairy Science Association. Published

  17. Comparative Phenotypical and Molecular Analyses of Arabidopsis Grown under Fluorescent and LED Light.

    Science.gov (United States)

    Seiler, Franka; Soll, Jürgen; Bölter, Bettina

    2017-06-13

    Comparative analyses of phenotypic and molecular traits of Arabidopsis thaliana grown under standardised conditions is still a challenge using climatic devices supplied with common light sources. These are in most cases fluorescent lights, which have several disadvantages such as heat production at higher light intensities, an invariable spectral output, and relatively rapid "ageing". This results in non-desired variations of growth conditions and lowers the comparability of data acquired over extended time periods. In this study, we investigated the growth behaviour of Arabidopsis Col0 under different light conditions, applying fluorescent compared to LED lamps, and we conducted physiological as well as gene expression analyses. By changing the spectral composition and/or light intensity of LEDs we can clearly influence the growth behaviour of Arabidopsis and thereby study phenotypic attributes under very specific light conditions that are stable and reproducible, which is not necessarily given for fluorescent lamps. By using LED lights, we can also roughly mimic the sun light emission spectrum, enabling us to study plant growth in a more natural-like light set-up. We observed distinct growth behaviour under the different light regimes which was reflected by physiological properties of the plants. In conclusion, LEDs provide variable emission spectra for studying plant growth under defined, stable light conditions.

  18. Comparative Phenotypical and Molecular Analyses of Arabidopsis Grown under Fluorescent and LED Light

    Directory of Open Access Journals (Sweden)

    Franka Seiler

    2017-06-01

    Full Text Available Comparative analyses of phenotypic and molecular traits of Arabidopsis thaliana grown under standardised conditions is still a challenge using climatic devices supplied with common light sources. These are in most cases fluorescent lights, which have several disadvantages such as heat production at higher light intensities, an invariable spectral output, and relatively rapid “ageing”. This results in non-desired variations of growth conditions and lowers the comparability of data acquired over extended time periods. In this study, we investigated the growth behaviour of Arabidopsis Col0 under different light conditions, applying fluorescent compared to LED lamps, and we conducted physiological as well as gene expression analyses. By changing the spectral composition and/or light intensity of LEDs we can clearly influence the growth behaviour of Arabidopsis and thereby study phenotypic attributes under very specific light conditions that are stable and reproducible, which is not necessarily given for fluorescent lamps. By using LED lights, we can also roughly mimic the sun light emission spectrum, enabling us to study plant growth in a more natural-like light set-up. We observed distinct growth behaviour under the different light regimes which was reflected by physiological properties of the plants. In conclusion, LEDs provide variable emission spectra for studying plant growth under defined, stable light conditions.

  19. Image quality of a novel light-emitting diode (LED)-illuminated colonoscope.

    Science.gov (United States)

    Sasaki, Sho; Nishikawa, Jun; Yanai, Hideo; Nakamura, Munetaka; Nishimura, Junichi; Goto, Atsushi; Kiyotoki, Shu; Saito, Mari; Hamabe, Kouichi; Tanabe, Ryo; Nakamura, Yohei; Tokiyama, Hiroshi; Hashimoto, Shinichi; Okamoto, Takeshi; Higaki, Shingo; Kurai, Satoshi; Ogihara, Hiroyuki; Hamamoto, Yoshihiko; Sakaida, Isao

    2016-10-01

    Light-emitting diodes (LEDs) are used widely for their high luminous efficiency and durability. We developed a novel prototype high definition endoscope with white LEDs and evaluated the image quality it produced against a commercial endoscope with conventional light source. The specifications of both colonoscopes were identical, except for the LED light source at the tip of the prototype. We examined 20 patients with rectal or sigmoid colon lesions and the image quality was evaluated in 40 images (one image from the LED colonoscope and one from the conventional colonoscope for each lesion) by three endoscopists. We additionally evaluated the 17 videos recorded with the LED colonoscope that were available. Image quality, mucosal and vascular color, and luminous distribution and intensity were scored on a 5-point scale. The mean score for vascular color given by one evaluator was significantly higher using the LED colonoscope than using the conventional colonoscope. The mean scores for mucosal color and luminous intensity from another evaluator were significantly lower with the LED colonoscope than with the conventional colonoscope. There were no significant differences in the luminous distribution scores for any of the evaluators. The image quality of the videos was evaluated as being similar with both colonoscopes. Image quality from the LED and conventional colonoscopes were similar, although the luminous intensity of the LEDs is inferior to that of the conventional light source at the present time. © Georg Thieme Verlag KG Stuttgart · New York.

  20. Time reduction of light curing: Influence on conversion degree and microhardness of orthodontic composites.

    Science.gov (United States)

    Amato, Patrícia Alves Ferreira; Martins, Renato Parsekian; dos Santos Cruz, Carlos Alberto; Capella, Marisa Veiga; Martins, Lídia Parsekian

    2014-07-01

    The aim of this study was to assess the influence of curing time and power on the degree of conversion and surface microhardness of 3 orthodontic composites. One hundred eighty discs, 6 mm in diameter, were divided into 3 groups of 60 samples according to the composite used-Transbond XT (3M Unitek, Monrovia, Calif), Opal Bond MV (Ultradent, South Jordan, Utah), and Transbond Plus Color Change (3M Unitek)- and each group was further divided into 3 subgroups (n = 20). Five samples were used to measure conversion, and 15 were used to measure microhardness. A light-emitting diode curing unit with multiwavelength emission of broad light was used for curing at 3 power levels (530, 760, and 1520 mW) and 3 times (8.5, 6, and 3 seconds), always totaling 4.56 joules. Five specimens from each subgroup were ground and mixed with potassium bromide to produce 8-mm tablets to be compared with 5 others made similarly with the respective noncured composite. These were placed into a spectrometer, and software was used for analysis. A microhardness tester was used to take Knoop hardness (KHN) measurements in 15 discs of each subgroup. The data were analyzed with 2 analysis of variance tests at 2 levels. Differences were found in the conversion degree of the composites cured at different times and powers (P light cured at 8.5 seconds (80.7%) and 6 seconds (79.0%), but not at 3 seconds (75.0%). The conversion degrees of the composites were different, with group 3 (87.2%) higher than group 2 (83.5%), which was higher than group 1 (64.0%). Differences in microhardness were also found (P Curing time can be reduced up to 6 seconds by increasing the power, with a slight decrease in the degree of conversion at 3 seconds; the decrease has a positive effect on the surface microhardness. Copyright © 2014 American Association of Orthodontists. Published by Mosby, Inc. All rights reserved.

  1. High-output LED-based light engine for profile lighting fixtures with high color uniformity using freeform reflectors.

    Science.gov (United States)

    Gadegaard, Jesper; Jensen, Thøger Kari; Jørgensen, Dennis Thykjær; Kristensen, Peter Kjær; Søndergaard, Thomas; Pedersen, Thomas Garm; Pedersen, Kjeld

    2016-02-20

    In the stage lighting and entertainment market, light engines (LEs) for lighting fixtures are often based on high-intensity discharge (HID) bulbs. Switching to LED-based light engines gives possibilities for fast switching, additive color mixing, a longer lifetime, and potentially, more energy-efficient systems. The lumen output of a single LED is still not sufficient to replace an HID source in high-output profile fixtures, but combining multiple LEDs can create an LE with a similar output, but with added complexity. This paper presents the results of modeling and testing such a light engine. Custom ray-tracing software was used to design a high-output red, green and blue LED-based light engine with twelve CBT-90 LEDs using a dual-reflector principle. The simulated optical system efficiency was 0.626 with a perfect (R=1) reflector coating for light delivered on a target surface through the entire optical system. A profile lighting fixture prototype was created, and provided an output of 6744 lumen and an efficiency of 0.412. The lower efficiency was mainly due to a non-optimal reflector coating, and the optimized design is expected to reach a significantly higher efficiency.

  2. Time effectiveness of Ultraviolet C light (UVC) emitted by Light Emitting Diodes (LEDs) in reducing stethoscope contamination

    OpenAIRE

    Messina, Gabriele; Fattorini, Mattia; Nante, Nicola; Rosadini, Daniele; Serafini, Andrea; Tani, Marco; Cevenini, Gabriele

    2016-01-01

    Today it is well demonstrated that stethoscopes can be as contaminated as hands, which are a recognized source of Health-Care Associated Infections (HCAIs). Ultraviolet C (UVC) light has proven disinfection capacity and the innovative UVC technology of Light Emitting Diode (LED) shows several potential benefits. To verify whether the use of UVC LEDs is effective and reliable in stethoscope membrane disinfection after prolonged use, a pre-post intervention study was conducted. A total of 1668 ...

  3. Design and radiation tests on a LED based emergency evacuation directional lighting

    CERN Document Server

    Trikoupis, Nikolaos

    2017-01-01

    A LED (Light Emitting Diode) based directional lighting system has been designed to indicate the best evacuation direction for applications like the Large Hadron Collider (LHC) tunnel. The design includes constraints for redundancy required by safety systems and for components selection by radiation effects. Most of the literature for radiation effects on LEDs concern digital communications systems, although some recent reports do exist for visible spectrum power LEDs and the reduction in light output versus dose is coherent with the results presented in this paper. Prototype lighting units were irradiated in CERN’s CHARM facility up to a Total Integrated Dose (TID) of 870 Gy and no failures were observed. This paper describes the basic design, presents field tests and the effects of radiation on the LEDs luminance.

  4. Efficient light extraction from GaN LEDs using gold-coated ZnO nanoparticles

    KAUST Repository

    Alhadidi, A.

    2015-11-01

    We experimentally demonstrate the effect of depositing gold-coated ZnO nanoparticles on the surface of GaN multi-quantum well LED structures. We show that this method can significantly increase the amount of extracted light.

  5. Best practices : bus signage for persons with visual impairments : light-emitting diode (LED) signs

    Science.gov (United States)

    2004-01-01

    This best-practices report provides key information regarding the use of Light-Emitting Diode (LED) sign technologies to present destination and route information on transit vehicles. It will assist managers and engineers in the acquisition and use o...

  6. Influence of different light-curing units on the surface roughness of restorative materials: in situ study

    Directory of Open Access Journals (Sweden)

    Juliane Cristina Ciccone-Nogueira

    2007-09-01

    Full Text Available The aim of this study was to evaluate the influence of different light sources (LED and Halogen lamp on the roughness (superficial of composite resin (Filtek Z250, Filtek P60, Charisma and Durafill varying post-irradiation times, in an in situ experiment. For this purpose, 80 specimens were made in polyurethane moulds. Ten volunteers without medicament use and good oral condition were selected and from them study moulds were obtained. A palatal intra-oral acrylic resin appliance was made for each of the subjects of the experiment. In each appliance, two specimens of each material were fixed (LED/Halogen lamp - control group. Roughness tests were performed immediately and 30 days after initial light-curing. Statistical analysis was performed using ANOVA. Statistically significant difference was observed only between post-irradiation times, where the 30th day showed the highest roughness values. It be concluded that roughness was influenced only by post-irradiation times, presenting the 30- days period inferior behavior.

  7. Effect of different light curing units on Knoop hardness and temperature of resin composite

    Directory of Open Access Journals (Sweden)

    Guiraldo Ricardo

    2009-01-01

    Full Text Available Aim: To evaluate the influence of quartz tungsten halogen and plasma arc curing (PAC lights on Knoop hardness and change in polymerization temperature of resin composite. Materials and Methods: Filtek Z250 and Esthet X composites were used in the shade A3. The temperature increase was registered with Type-k thermocouple connected to a digital thermometer (Iopetherm 46. A self-cured polymerized acrylic resin base was built in order to guide the thermocouple and to support the dentin disk of 1.0 mm thickness obtained from bovine tooth. On the acrylic resin base, elastomer mold of 2.0 mm was adapted. The temperature increase was measured after composite light curing. After 24 h, the specimens were submitted to Knoop hardness test (HMV-2000, Shimadzu, Tokyo, Japan. Data were submitted to ANOVA and Tukey′s test (a = 0.05. Results: For both composites, there were no significant differences (P > 0.05 in the top surface hardness; however, PAC promoted statistically lower (P < 0.05 Knoop hardness number values in the bottom. The mean temperature increase showed no significant statistical differences (P > 0.05. Conclusion: The standardized radiant exposure showed no influence on the temperature increase of the composite, however, showed significant effect on hardness values.

  8. Effect of different light curing units on Knoop hardness and temperature of resin composite.

    Science.gov (United States)

    Guiraldo, Ricardo Danil; Consani, Simonides; Xediek Consani, Rafael Leonardo; Mendes, Wilson Batista; Lympius, Thais; Coelho Sinhoreti, Mario Alexandre

    2009-01-01

    To evaluate the influence of quartz tungsten halogen and plasma arc curing (PAC) lights on Knoop hardness and change in polymerization temperature of resin composite. Filtek Z250 and Esthet X composites were used in the shade A3. The temperature increase was registered with Type-k thermocouple connected to a digital thermometer (Iopetherm 46). A self-cured polymerized acrylic resin base was built in order to guide the thermocouple and to support the dentin disk of 1.0 mm thickness obtained from bovine tooth. On the acrylic resin base, elastomer mold of 2.0 mm was adapted. The temperature increase was measured after composite light curing. After 24 h, the specimens were submitted to Knoop hardness test (HMV-2000, Shimadzu, Tokyo, Japan). Data were submitted to ANOVA and Tukey's test (alpha = 0.05). For both composites, there were no significant differences (P > 0.05) in the top surface hardness; however, PAC promoted statistically lower (P 0.05). The standardized radiant exposure showed no influence on the temperature increase of the composite, however, showed significant effect on hardness values.

  9. Setup of a LED light-pulser system for the OLYMPUS experiment; Aufbau eines LED-Lichtpulsersystems fuer das OLYMPUS-Experiment

    Energy Technology Data Exchange (ETDEWEB)

    Rehman, Waqaas

    2011-12-15

    The aim of this thesis consists in the construction and test of an external light-calibration system based on light-emitting diodes (LED) for the application at the symmetric Moller/Bhabha (SYMB) luminosity monitor. In chapter 2 the theoretical foundations of the OLYMPUS experiment, especially of the SYMB luminosity monitor are explained. Thereafter in chapter 3 the details of the setup of the OLYMPUS experiment and the fundamental properties of the SYMB detectors are discussed. In chapter 4 the whole concept of the LED light-pulser system is treated. In chapter 5 then test measurements with the ready LED light-pulser system are described. Thereby the light source shall be optimized in the shape that thereafter light pulses with short signal width are producable. Also different measurements for the unique characterization of the systems are performed. In chapter 6 light-intensity measurements during the operation of the LED light-pulser system are described.

  10. Caenorhabditis elegans as a model to study the impact of exposure to light emitting diode (LED) domestic lighting.

    Science.gov (United States)

    Abdel-Rahman, Fawzia; Okeremgbo, Bethel; Alhamadah, Fatimah; Jamadar, Sakha; Anthony, Kevin; Saleh, Mahmoud A

    2017-04-16

    This study aimed to investigate the biological impact of exposure on domestic light emitting diodes (LED) lighting using the free-living nematode Caenorhabditis elegans as a model. Nematodes were separately exposed to white LED light covering the range of 380-750 nm, blue light at 450 nm and black light at 380-420 nm for one life cycle (egg to adult) with dark exposure as the control. Each light range induced stress to the nematode C. elegans such as reducing the number of the hatched eggs and/or delayed the maturation of the hatched eggs to the adult stage. In addition, it lowered or prevented the ability of adults to lay eggs and impaired the locomotion in the exposed worms. The observed type of biological stress was also associated with the production of reactive oxygen species (ROS) as compared to nematodes grown in the dark. It is concluded that the blue light component of white LED light may cause health problems, and further investigation is required to test commercial brands of white LEDs that emit different amounts of blue light.

  11. Influence of adhesion promoters and curing-light sources on the shear bond strength of orthodontic brackets

    Directory of Open Access Journals (Sweden)

    Claudia Tavares Machado

    2012-01-01

    Conclusions: The conventional orthodontic adhesive presented higher bond strength than the nanofilled composite, although both materials interacted similarly to the teeth. The curing-light devices tested did not influence on bond strength of orthodontic brackets.

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

    Science.gov (United States)

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

    2015-04-01

    In the present study, the effects of red and blue LED lights on the accumulation of ascorbic acid (AsA) were investigated in the juice sacs of three citrus varieties, Satsuma mandarin, Valencia orange, and Lisbon lemon. The results showed that the blue LED light treatment effectively increased the AsA content in the juice sacs of the three citrus varieties, whereas the red LED light treatment did not. By increasing the blue LED light intensity, the juice sacs of the three citrus varieties accumulated more AsA. Moreover, continuous irradiation with blue LED light was more effective than pulsed irradiation for increasing the AsA content in the juice sacs of the three citrus varieties. Gene expression results showed that the modulation of AsA accumulation by blue LED light was highly regulated at the transcription level. The up-regulation of AsA biosynthetic genes (CitVTC1, CitVTC2, CitVTC4, and CitGLDH), AsA regeneration genes (CitMDAR1, CitMDAR2, and CitDHAR) and two GSH-producing genes (CitGR and CitchGR) contributed to these increases in the AsA content in the three citrus varieties. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

  13. Hybrid sunlight/LED illumination and renewable solar energy saving concepts for indoor lighting.

    Science.gov (United States)

    Tsuei, Chih-Hsuan; Sun, Wen-Shing; Kuo, Chien-Cheng

    2010-11-08

    A hybrid method for using sunlight and light-emitting diode (LED) illumination powered by renewable solar energy for indoor lighting is simulated and presented in this study. We can illuminate an indoor space and collect the solar energy using an optical switching system. When the system is turned off, the full spectrum of the sunlight is concentrated by a concentrator, to be absorbed by solar photovoltaic devices that provide the electricity to power the LEDs. When the system is turned on, the sunlight collected by the concentrator is split into visible and non-visible rays by a beam splitter. The visible rays pass through the light guide into a light box where it is mixed with LED light to ultimately provide uniform illumination by a diffuser. The non-visible rays are absorbed by the solar photovoltaic devices to provide electrical power for the LEDs. Simulation results show that the efficiency of the hybrid sunlight/LED illumination with the renewable solar energy saving design is better than that of LED and traditional lighting systems.

  14. Comparison of Light Emitting Diodes (LED) and Fluorescent Light on Suppression of Pineal Melatonin in the Rat

    Science.gov (United States)

    Winget, Charles M.; Heeke, D. S.; Holley, D. C.; Mele, G.; Brainard, G. C.; Hanifin, J. P.; Rollag, M. D.; Savage, Paul D. (Technical Monitor)

    1997-01-01

    To validate a novel LED array for use in animal habitat lighting by comparing its effectiveness to cool-white fluorescent (CWF) lighting in suppressing pineal gland melatonin. Male Sprague-Dawley rats, 175-200 g, were maintained under control conditions for 2 weeks (food and water ad lib, 12L: 12D CWF, 18 uW/square cm). Dark adapted animals (animals before lights on) were exposed to 5 min of LED or CWF light of similar spectral power distribution. Two groups of rats (LED vs. CWF) were compared at 5 light intensities (100, 40, 1, 1.0, and 0. 1 lux). A control group was placed into the exposure apparatus but not exposed to light. After exposure, pineal glands were rapidly removed and assayed for melatonin by RIA. Results. The dark-exposed control groups matched with the 5 intensity groups (100, 40, 10, 1.0, and 0.1 lux) showed mean + SEM pineal melatonin values of 1167 +/- 136, 1569 +/- 126, 353 +/- 34, 650 +/- 124, and 464 +/- 85, pg/ml respectively. The corresponding CWF exposure data were 393 1 41, 365 +34, 257 +/- 13, 218 +/- 42, and 239 +/- 71 pg/ml, respectively. Corresponding LED exposure data were 439 +/- 25, 462 +/- 50, 231 +/- 6, 164 +/- 12, and 158 +/- 12 pg/ml, respectively. Rats exposed to both experimental light conditions at all illuminances studied showed significant melatonin suppression (p less than 0.01, ANOVA). In no case was the melatonin suppression induced by LED illuminance significantly different from the melatonin suppression elicited by the same intensity of CWF light. The results show that a novel LED light source can suppress pineal melatonin equal to that of a conventional CWF light source.

  15. Visible light cure characteristics of a cycloaliphatic polyester dimethacrylate alternative oligomer to bisGMA.

    Science.gov (United States)

    Vaidyanathan, Tritala K; Vaidyanathan, Jayalakshmi

    2015-12-01

    Objective : The goal of this study was to characterize the light curing characteristics of a new oligomer PEM-665 designed to be used as an alternative monomer to BisGMA. Materials and methods : PEM-665 (P) and BisGMA (B) solutions were prepared with triethylene glycol dimethacrylate (T) diluent in different weight proportions (70/30 and 50/50). Solutions containing 70% P and 30% T were designated as 70PT, 70%B and 30%T as 70BT, 50%P and 50%T as 50PT and 50%B and 50%T as 50BT. The initiators were CQ (EDMAB was used as amine accelerator for CQ) and DPO in 1% concentration. Eight solutions were prepared in a factorial design: 70PT/DPO; 70PT/CQ; 50PT/DPO; 50PT/CQ; 70BT/DPO; 70BT/CQ; 50BT/DPO; 50BT/CQ. BISCO VIP visible light was used to cure the monomer solutions using 30 s exposure time and 400 W power setting. TA Instruments Differential Scanning Calorimeter (DSC 2910) was used to determine the heat of cure (J/g) during polymerization at 37 °C, from which molar heat of cure (kJ/mole) and %Conversion values were estimated. Results : Range of mean values as a function monomer selections were: heat of cure (J/g): 161.7 for 70PT/DPO system to 198.6 for 50BT/CQ system; molar heat of cure (kJ/mole): 67.3 for 70BT/DPO to 78.86 for 50PT/CQ; % conversion: 59.9 for 70BT/DPO to 70.3 for 50PT/CQ. Analysis of variance and Tukey HSD pairwise contrast showed statistically significant differences between % conversion means of PEM and BisGMA mixtures, with PEM mixtures showing significantly higher mean values. Conclusions : The results suggest that PEM-665 is a promising candidate material for dental polymer applications.

  16. Sensitivity to Ethephon Degreening Treatment Is Altered by Blue LED Light Irradiation in Mandarin Fruit.

    Science.gov (United States)

    Deng, Lili; Yuan, Ziyi; Xie, Jiao; Yao, Shixiang; Zeng, Kaifang

    2017-08-02

    Although citrus fruits are not climacteric, exogenous ethylene is widely used in the degreening treatment of citrus fruits. Irradiation with blue light-emitting diode (LED) light (450 nm) for 10 h can promote the formation of good coloration of ethephon-degreened fruit. This study evaluated the effect of blue LED light irradiation on the pigments contents of ethephon-degreened fruit and evaluated whether the blue LED light irradiation could influence the sensitivity of mandarin fruit to ethylene. The results indicated that blue light can accelerate the color change of ethephon-degreened fruit, accompanied by changes in plastid ultrastructure and chlorophyll and carotenoid contents. Ethephon-induced expressions of CitACS1, CitACO, CitETR1, CitEIN2, CitEIL1, and CitERF2 were enhanced by blue LED light irradiation, which increased the sensitivity to ethylene in ethephon-degreened fruits. These results indicate that blue LED light-induced changes in sensitivity to ethylene in mandarin fruit may be responsible for the improved coloration of ethephon-degreened mandarin fruits.

  17. Transmission of Curing Light through Moist, Air-Dried, and EDTA Treated Dentine and Enamel

    Directory of Open Access Journals (Sweden)

    E. Uusitalo

    2016-01-01

    Full Text Available Objective. This study measured light transmission through enamel and dentin and the effect of exposed dentinal tubules to light propagation. Methods. Light attenuation through enamel and dentin layers of various thicknesses (1 mm, 2 mm, 3 mm, and 4 mm was measured using specimens that were (1 moist and (2 air-dried (n=5. Measurements were repeated after the specimens were treated with EDTA. Specimens were transilluminated with a light curing unit (maximum power output 1869 mW/cm2, and the mean irradiance power of transmitting light was measured. The transmission of light through teeth was studied using 10 extracted intact human incisors and premolars. Results. Transmitted light irradiance through 1 mm thick moist discs was 500 mW/cm2 for enamel and 398 mW/cm2 for dentin (p<0.05. The increase of the specimen thickness decreased light transmission in all groups (p<0.005, and moist specimens attenuated light less than air-dried specimens in all thicknesses (p<0.05. EDTA treatment increased light transmission from 398 mW/cm2 to 439 mW/cm2 (1 mm dentin specimen thickness (p<0.05. Light transmission through intact premolar was 6.2 mW/cm2 (average thickness 8.2 mm and through incisor was 37.6 mW/cm2 (average thickness 5.6 mm. Conclusion. Light transmission through enamel is greater than that through dentin, probably reflecting differences in refractive indices and extinction coefficients. Light transmission through enamel, dentin, and extracted teeth seemed to follow Beer-Lambert’s law.

  18. Assessment of filament led bulbs with respect to temporal light artefacts

    DEFF Research Database (Denmark)

    Lindén, Johannes; Thorseth, Anders; Corell, Dennis Dan

    2017-01-01

    Temporal light artefacts, abbreviated TLAs (including flicker, stroboscopic effect and phantom arrays), i.e. undesired time modulation in luminance from a light source, has shown to be a threat to wider SSL adoption especially related to dimming functions and low-quality LED products. This is due...

  19. Investing in Their Future: Portland’s Purchase and Conversion of an LED Street Lighting System

    Energy Technology Data Exchange (ETDEWEB)

    Kinzey, B. R. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Rosinbum, T. [Portland Bureau of Transportation, Portland, OR (United States)

    2015-08-28

    During the ongoing process of converting its streetlights from high-pressure sodium to LED, the city of Portland, Oregon, purchased a large portion of its street lighting system and encountered a range of issues among the stakeholders. This report identifies some of the challenges involved and discusses how they were addressed, in order to help inform and facilitate future lighting transitions elsewhere.

  20. Protective effect of monochromatic red light of LED against the oxidative effects of microwave radiation

    International Nuclear Information System (INIS)

    Tsibulyin, O.S.; Yakimenko, Yi.L.; Sidorik, Je.P.

    2016-01-01

    Oxidative mechanisms of hazard effects of radiofrequency radiation (RFR) were elucidated recently, and this opens new approaches for the protection of living organisms against harmful effects of RFR. We demonstrate the significant protective effect and the antioxidant potential of monochromatic red light of light-emitting diodes (LED, λ = 630- 650 nm) in microwave GSM 900 MHz exposed embryos of Japanese quails

  1. General dental practitioners' knowledge of polymerisation of resin-based composite restorations and light curing unit technology.

    Science.gov (United States)

    Santini, A; Turner, S

    2011-09-23

    Clinical successful use of resin-based composite restorations (RBCs) depends on knowledge of material and light curing unit (LCU) related factors. The purpose of this study was to evaluate general dental practitioners' knowledge of polymerisation of RBCs and LCU technology. Members of the Active Research Group of the Faculty of General Dental Practice (UK) in England, Scotland and Wales engaged in primary dental care were sent a letter introducing the study and asking for their cooperation, followed by an email containing a link to the online survey questionnaire, hosted on Surveymonkey.com. The questionnaire enquired about current LCUs, and asked a series of questions on material science. Sixty-six percent of the 274 members contacted responded. Fifty-seven percent used LED units, 25% quartz tungsten halogen (QTH), and 1% plasma arc (missing: 17%). Thirty percent reported having access to a radiometer. Appropriate responses regarding the degree of conversion of composite and adhesive materials were given by 32% and 23% respectively, and 22% agreed that LED and QTH LCUs had comparable efficiency in polymerising composites. Thirty-three percent were aware that RBCs eluted substances that may have adverse local or systemic consequences. Fifty-eight percent stated that if polymerisation of RBC is slowed down, polymerisation stress will be lower, and 43% said that polymerisation shrinkage will be reduced if the degree of conversion is reduced. Knowledge (measured by appropriate responses to these questions) was not related to years since qualification (r=-0.05, n=168, p=0.53). The study suggests that dentists' knowledge of curing RBC restorations and LCUs is poor. This indicates that there is a need for training and guidance in this aspect of primary dental care.

  2. Color temperature tunable white-light LED cluster with extrahigh color rendering index.

    Science.gov (United States)

    Zhang, Minhao; Chen, Yu; He, Guoxing

    2014-01-01

    The correlated color temperature (CCT) tunable white-light LED cluster with extrahigh color rendering property has been found by simulation and fabricated, which consists of three WW LEDs (CCT = 3183 K), one red LED (634.1 nm), one green LED (513.9 nm), and one blue LED (456.2 nm). The experimental results show that this cluster can realize the CCT tunable white-lights with a color rendering index (CRI) above 93, special CRI R9 for strong red above 90, average value of the special CRIs of R9 to R12 for the four saturated colors (red, yellow, green, and blue) above 83, and luminous efficacies above 70 lm/W at CCTs of 2719 K to 6497 K.

  3. Lighting and social practices - what role does lighting play for low energy house (LEH) households and LED frontrunners?

    DEFF Research Database (Denmark)

    Jensen, Charlotte Louise

    As lighting in Danish households consume approximately 1.3 TWh every year, reducing electricity consumption from lighting is important. Studies have shown that a mere substitution of inefficient lighting technologies towards more efficient ones may not be possible, as many social and cultural...... dimensions influence how people use and relate to lighting. Assessing how very distinctive contexts of households (that diverge from an exemplary kind of household), such as low energy houses and LED frontrunner households, use and understand lighting, may give some insight into what may trigger or hamper...

  4. LEDs in automotive lighting and signaling: a customer point of view

    Science.gov (United States)

    Berlitz, Stephan; Heider, Christian

    2007-09-01

    The development of brand specific front and tail lights in cooperation with the stylists is the assignment of automobile lighting. Highest car safety, attractive styling, differentiation in the traffic situation and environment friendliness are the project limits. LED technology has the potential to extend these limits. The LED technology will have to improve, but it is also enhanced by new sensor technologies that introduce new functionalities. The implementation of a possible roadmap depends on right technologies at the right time. For new styling ideas and functional innovations further steps in lighting technology are necessary. The document will show a car makers view on possible innovation ideas.

  5. LED surgical lighting system with multiple free-form surfaces for highly sterile operating theater application.

    Science.gov (United States)

    Liu, Peng; Zhang, Yaqin; Zheng, Zhenrong; Li, Haifeng; Liu, Xu

    2014-06-01

    Although the ventilation system is widely employed in the operating theater, a strictly sterile surgical environment still cannot be ensured because of laminar disturbance, which is mainly caused by the surgical lighting system. Abandoning traditional products, we propose an LED surgical lighting system, which can alleviate the laminar disturbance and provide an appropriate lighting condition for surgery. It contains a certain amount of LED lens units, which are embedded in the ceiling and arranged around the air supply smallpox. The LED lens unit integrated with an LED light source and a free-form lens is required to produce a uniform circular illumination with a large tolerance to the change of lighting distance. To achieve such a dedicated lens, two free-form refractive surfaces, which are converted into two ordinary differential equations by the design method presented in this paper, are used to deflect the rays. The results show that the LED surgical lighting system can provide an excellent illumination environment for surgery, and, apparently, the laminar disturbance also can be relieved.

  6. Study and Implementation of White Power-LED Based Indoor Lighting Application for the Healthcare Sector

    Science.gov (United States)

    Chakraborty, A.; Ganguly, R.

    With the current technological growth in the field of device fabrication, white power-LED's are available for solid state lighting applications. This is a paradigm shift from electrical lighting to electronic lighting. The implemented systems are showing some promise by saving a considerable amount of energy as well as providing a good and acceptable illumination level. However, the `useful life' of such devices is an important parameter. If the proper device is not chosen, the desired reliability and performance will not be obtained. In the present work, different parameters associated with reliability of such LED's are studied. Four different varieties of LED's are put to test the `useful life' as per IESNA LM 79 standard. From the results obtained, the proper LED is chosen for further application. Subsequently, lighting design is done for a hospital waiting room (indoor application) with 24 × 7 lighting requirements for replacement of existing CFLs there. The calculations show that although the initial cost is higher for LED based lighting, yet the savings on energy and replacement of the lamp results in a payback time of less than a year.

  7. Artificial Lighting Protection of Mauna Kea Observatories: An Experiment to Replace LPS Street Lighting With LEDs in Waikoloa Village, HI

    Science.gov (United States)

    Craine, Eric R.; Craine, Brian L.

    2016-06-01

    Segments of the astronomical community have long lobbied in support of the use of Low Pressure Sodium (LPS) street lights as a method of minimizing impacts of sky glow on neighboring observatories. There has been vociferous objection to the replacement of LPS by Light Emitting Diode (LED) street lights. Such replacement is being precipitated by advances in lighting technologies, high economic efficiencies of LEDs, and plummeting interest in manufacturing LPS fixtures. Waikoloa Village, HI, located on the western slopes of Mauna Kea, home to major northern hemisphere observatories, has for many years been almost exclusively illuminated by LPS lighting. During the winter of 2015-2016 the County of Hawai’i Department of Public Works, Traffic Division replaced the approximately 550 LPS street lights in the community with Filtered LED (FLED) fixtures on a one-for-one basis. About 100 other LPS lights on private properties in the community were similarly replaced by the lighting manufacturer. This retrofit offered an excellent opportunity to make measurements of lighting parameters in the community before and after the retrofit process. Measurements were made using satellite, airborne, and ground based observations, and included photometric, photographic, and spectroscopic measurements. Data analyzed included integrated brightness of the community, zenith angle function brightness distributions, and spectral energy distributions. We present the results of these observations and discuss their implications for future protection of astronomical observatory sites.

  8. [Effects of different LED light qualities on photosynthetic characteristics, fruit production and quality of strawberry].

    Science.gov (United States)

    Liu, Qing; Lian, Hai-feng; Liu, Shi-qi; Sun, Ya-li; Yu, Xin-hui; Guo, Hui-ping

    2015-06-01

    Taking 'Miaoxiang No.7' strawberry as material, full red light, full blue light, full yellow light, full white light, red/blue/yellow (7/2/1), red/blue (7/2) light generated by light emitting diode (LED) was applied to accurately modulate with white light generated as control. The indicators of photosynthetic and fluorescence parameters, pigment content, fruit production and quality, root activity were investigated. The effects of light quality under the light intensity (500 µmol · m(-2) · s(-1)) on the photosynthetic characteristic, fruit production and quality of strawberry were studied. The results showed that the red light could increase photosynthetic parameters (Pn, Tr), while blue light had inhibitory effect. Intercellular CO2 concentration (Ci) and conductance (g(s)) were the highest under blue light. The fluorescence parameters were significantly affected by light quality, Fo, Fm and Φ PS II the highest under red light, but values of the maximal photochemical of PS II (Fv/Fm), Fv/Fo and Fm/Fo highest under red/blue/yellow (7/2/1). In addition, the soluble solids content and vitamin C were highest under red light, the blue light could increase protein and titratable acid, sugar-acid ratio was the highest under red/blue/yellow (7/2/1). Comprehensive analysis indicated that red/blue/yellow (7/2/1) was more beneficial to the increase of pigment contents of leaves, fruit production and some qualities of strawberry.

  9. Neuroglobin - a potential biological marker of retinal damage induced by LED light.

    Science.gov (United States)

    Yu, Z-L; Qiu, S; Chen, X-C; Dai, Z-H; Huang, Y-C; Li, Y-N; Cai, R-H; Lei, H-T; Gu, H-Y

    2014-06-13

    Neuroglobin (NGB), a protein highly expressed in the retina, has been shown to be up-regulated to protect neurons from hypoxic and ischemic injuries. It exhibits neuroprotective functions and plays an important role in the survival of neurons. Recent studies show that light-emitting diode (LED) white light emitted significant amounts of blue light (short-wavelength), which may be harmful to retinal cells, but the studies about biomarkers for evaluating the damage from LED white light are still insufficient. In our study, we found that NGB levels in the retina showed a twofold increase and peaked at 1h after a 1-h exposure to blue light (453 nm) which did not cause damage to the retina. However, retinal damage was observed after 2h of blue-light irradiation, which induced an approximate sevenfold increase of NGB levels as confirmed by Western blot and RT-PCR analysis. Immunofluorescence study demonstrated that NGB was predominantly up-regulated in the ganglion cell layer (GCL), plexiform layer (PL) and photoreceptor layer (PRL). We also examined Ngb mRNA and protein expression in the damaged retina induced by light of other wavelengths given equal photon fluxes. The LED red light (625 nm), green light (527 nm) and blue light (453 nm) increased the expression of NGB and caused TdT-mediated dUTP nick-end labeling-positive cells, especially in the blue-light group. In addition, a negative correlation between NGB and rhodopsin was observed. These findings suggested that there was a correlation between NGB expression and the severity of the retinal damage, indicating NGB's potential function as a biological marker of retinal damage induced by LED light. Copyright © 2014 IBRO. Published by Elsevier Ltd. All rights reserved.

  10. Spectral Changes of Cucumber Leaf During Adaptation of the Photosynthetic Apparatus to Led Lighting

    Science.gov (United States)

    Viazau, Y. V.; Kozel, N. V.; Domanski, V. P.; Shalygo, N. V.

    2015-01-01

    A direct correlation between the change of fluorescence at 77 K in leaves of cucumber plants growing under LED lighting and the change of the quantitative composition of structural proteins of PS1 and PS2 was established. It was shown that light absorption and the utilization of its energy during the long-term action of narrow-band light on cucumber plants could affect considerably spectra of the leaves because of changes in the synthesis of photosystem structural proteins.

  11. PV LED ENGINE characterization lab for stand alone light-to-light systems

    DEFF Research Database (Denmark)

    Poulsen, Peter Behrensdorff; Thorsteinsson, Sune; Lindén, Johannes

    2015-01-01

    PV-powered lighting systems, light-to-light systems (L2L), offer outdoor lighting where it is elsewhere cumbersome to enable lighting. Application of these systems at high latitudes, where the difference in day length between summer and winter is large and the solar energy is low requires smart...... dimming functions for reliable lighting. A barrier for exploiting use of standalone solar lighting for the urban environment seem to be lack of knowledge and lack of available tools for proper dimensioning. In this work the development of powerful dimensioning tool is described and initial measurements...

  12. Application of ultraviolet light-emitting diodes (UV-LEDs) for water disinfection: A review.

    Science.gov (United States)

    Song, Kai; Mohseni, Madjid; Taghipour, Fariborz

    2016-05-01

    Ultraviolet (UV) disinfection is an effective technology for the inactivation of pathogens in water and is of growing interest for industrial application. A new UV source - ultraviolet light-emitting diode (UV-LED) - has emerged in the past decade with a number of advantages compared to traditional UV mercury lamps. This promising alternative raises great interest in the research on application of UV-LEDs for water treatment. Studies on UV-LED water disinfection have increased during the past few years. This article presents a comprehensive review of recent studies on UV-LEDs with various wavelengths for the inactivation of different microorganisms. Many inconsistent and incomparable data were found from published studies, which underscores the importance of establishing a standard protocol for studying UV-LED inactivation of microorganisms. Different UV sensitivities to UV-LEDs and traditional UV lamps were observed in the literature for some microorganisms, which requires further investigation for a better understanding of microorganism response to UV-LEDs. The unique aspects of UV-LEDs improve inactivation effectiveness by applying LED special features, such as multiple wavelengths and pulsed illumination; however, more studies are needed to investigate the influencing factors and mechanisms. The special features of UV-LEDs offer the flexibility of novel reactor designs for a broad application of UV-LED reactors. Copyright © 2016 Elsevier Ltd. All rights reserved.

  13. LEDWIRE: A Versatile Networking Platform for Smart LED Lighting Applications Using LIN-Bus and WSNs

    Directory of Open Access Journals (Sweden)

    Dimitrios D. Piromalis

    2016-05-01

    Full Text Available In this paper, the architecture of a versatile networking and control platform for Light-Emitting Diode (LED lighting applications is presented, based on embedded wireless and wired networking technologies. All the possible power and control signals distribution topologies of the lighting fixtures are examined with particular focus on dynamic lighting applications with design metrics as the cost, the required wiring installation expenses and maintenance complexity. The proposed platform is optimized for applications where the grouping of LED-based lighting fictures clusters is essential, as well as their synchronization. With such an approach, the distributed control and synchronization of LED lighting fixtures' clusters is performed through a versatile network that uses the single wire Local Interconnect Network (LIN bus. The proposed networking platform is presented in terms of its physical layer architecture, its data protocol configuration, and its functionality for smart control. As a proof of concept, the design of a LED lighting fixture together with a LIN-to-IEEE802.15.4/ZigBee data gateway is presented.

  14. Effect of short curing times with a high-intensity light-emitting diode or high-power halogen on shear bond strength of metal brackets before and after thermocycling.

    Science.gov (United States)

    Cerekja, Erion; Cakirer, Banu

    2011-05-01

    To test the hypothesis that short curing times using a high-intensity light-emitting diode (LED) or high-power halogen are not associated with compromised shear bond strength (SBS) of metal brackets before and after thermocycling. Two hundred forty extracted human premolar teeth were divided into six groups of 40 each. Metal brackets were bonded using a light-cured composite (Transbond XT). In group 1 a conventional halogen light (Hilux) was used for 40 seconds. In groups 2, 3, and 4 a high-power halogen light (Swiss Master) was used for 2, 3, and 6 seconds, respectively. In groups 5 and 6 a high-intensity LED (Bluephase) was used for 10 and 20 seconds, respectively. After bonding, half of the specimens in each group were thermocycled, and all specimens were tested for SBS. After debonding, the bracket bases and the enamel surfaces were scored according to the Adhesive Remnant Index. Two-way analysis of variance detected significant differences in SBS values with respect to curing method (type of light-curing unit and curing time) (P  =  .0001) and thermocycling (P  =  .01). Tukey post hoc analysis showed that with or without thermocycling the mean SBS values of groups 1, 4, 5, and 6 were not significantly different, whereas group 2 showed the lowest SBS values. The predominant failure site for groups 2 and 3 was between the bracket and the adhesive and for groups 4, 5, 6 it was at the tooth/adhesive interface. Curing time can be reduced to 6 seconds with high-power halogen light and to 10 seconds with high-intensity LED without compromising in vitro SBS of metal brackets.

  15. Physiological and genetic characterization of plant growth and gravitropism in LED light sources

    Science.gov (United States)

    Deitzer, Gerald F.

    1994-01-01

    Among the many problems of growing plants in completely controlled environments, such as those anticipated for the space station and the CELSS program, is the need to provide light that is both adequate for photosynthesis and of proper quality for normal growth and development. NASA scientists and engineers have recently become interested in the possibility of utilizing densely packed, solid state, light emitting diodes (LED's) as a source for this light. Unlike more conventional incandescent or electrical discharge lamps, these sources are highly monochromatic and lack energy in spectral regions thought to be important for normal plant development. In addition, a recent observation by NASA scientist has suggested that infra-red LED's, that are routinely used as photographic safelights for plants grown in darkness, may interact with the ability of plants to detect gravity. In order to establish how plants respond to light from these LED light sources we carried out a series of experiments with known pigment mutants of the model mustard plant, Arabidopsis thaliana, growing in either a gravity field or on a clinostat to simulate a micro-gravity environment. Results indicate that only red light from the 665 nm LED's disrupts the ability of normal wildtype seedlings to detect a gravity stimulus. There was no consistent effect found for the far-red (735 nm) LED's or either of the infrared (880 nm or 935 nm) LED sources but both showed some effect in one or more of the genotypes tested. Of these five members of the phytochrome multigene family in Arabidopsis, only the phytochrome B pigment mutant (hy3) lacked the ability to detect gravity under all conditions. There was no effect of either micro-gravity (clinostat) or the infra-red LED's on the light induced inhibition of hypocotyl elongation. Measurements of the pigment phytochrome in oats also showed no photoconversion by 15 min irradiations with the infra-red LED's. We conclude that phytochrome B is required for the

  16. The effect of exposure time on diametral tensile strength of light-cured resin composite

    Directory of Open Access Journals (Sweden)

    Marzia M Tetelepta

    2016-06-01

    Full Text Available Repetition or extend the exposure time in using light-cured resin composite are often done by practitioners in order to get a higher mechanical strength. Nevertheless, failure still can occur. Therefore, the aim of this study was to evaluate the effect of exposure time on Diametral Tensile Strength (DTS of two different resin composite used for provisional crown and bridge restoration and filling materials. A total of 60 cylindrical specimens (6mm diameter x 3mm thickness were divided into three groups (n=10. The first group was cured as recommended by the manufacturer, the second group were cured two times, and the third group were cured three times. Furthermore, specimens were immersed in distilled water for 24 hours at a temperature of 37 °C. DTS were tested by universal testing machine and the results were analyzed by one-way ANOVA continued with Post Hoc Tamhane to see the difference between the groups. The results showed DTS composite as filling materials was significantly higher compared with the resin composite  for provisional crown and bridge restoration. DTS of composite as filling materials in first group had a higher value than first  and third groups. The composite for the provisional crown and bridge restoration in second group had a lower DTS value than in first and third groups. In third group, DTS increased but not significantly. DTS also could be influenced by the composition of filler content and type of matrix. The conclusion of this study was to extend the exposure time can weaken the DTS resin composite.

  17. Effect of multi-wavelength irradiation on color characterization with light-emitting diodes (LEDs)

    Science.gov (United States)

    Park, Hyeong Ju; Song, Woosub; Lee, Byeong-Il; Kim, Hyejin; Kang, Hyun Wook

    2017-06-01

    In the current study, a multi-wavelength light-emitting diode (LED)-integrated CMOS imaging device was developed to investigate the effect of various wavelengths on multiple color characterization. Various color pigments (black, red, green, and blue) were applied on both white paper and skin phantom surfaces for quantitative analysis. The artificial skin phantoms were made of polydimethylsiloxane (PDMS) mixed with coffee and TiO2 powder to emulate the optical properties of the human dermis. The customized LED-integrated imaging device acquired images of the applied pigments by sequentially irradiating with the LED lights in the order of white, red, green, and blue. Each color pigment induced a lower contrast during illumination by the light with the equivalent color. However, the illumination by light with the complementary (opposite) color increased the signal-to-noise ratio by up to 11-fold due to the formation of a strong contrast ( i.e., red LED = 1.6 ± 0.3 vs. green LED = 19.0 ± 0.6 for red pigment). Detection of color pigments in conjunction with multi-wavelength LEDs can be a simple and reliable technique to estimate variations in the color pigments quantitatively.

  18. Effects of white light-emitting diode (LED) exposure on retinal pigment epithelium in vivo.

    Science.gov (United States)

    Jaadane, Imene; Villalpando Rodriguez, Gloria Elisa; Boulenguez, Pierre; Chahory, Sabine; Carré, Samuel; Savoldelli, Michèle; Jonet, Laurent; Behar-Cohen, Francine; Martinsons, Christophe; Torriglia, Alicia

    2017-12-01

    Ageing and alteration of the functions of the retinal pigment epithelium (RPE) are at the origin of lost of vision seen in age-related macular degeneration (AMD). The RPE is known to be vulnerable to high-energy blue light. The white light-emitting diodes (LED) commercially available have relatively high content of blue light, a feature that suggest that they could be deleterious for this retinal cell layer. The aim of our study was to investigate the effects of "white LED" exposure on RPE. For this, commercially available white LEDs were used for exposure experiments on Wistar rats. Immunohistochemical stain on RPE flat mount, transmission electron microscopy and Western blot were used to exam the RPE. LED-induced RPE damage was evaluated by studying oxidative stress, stress response pathways and cell death pathways as well as the integrity of the outer blood-retinal barrier (BRB). We show that white LED light caused structural alterations leading to the disruption of the outer blood-retinal barrier. We observed an increase in oxidized molecules, disturbance of basal autophagy and cell death by necrosis. We conclude that white LEDs induced strong damages in rat RPE characterized by the breakdown of the BRB and the induction of necrotic cell death. © 2017 The Authors. Journal of Cellular and Molecular Medicine published by John Wiley & Sons Ltd and Foundation for Cellular and Molecular Medicine.

  19. PV led engine characterization lab for standalone light to light systems

    DEFF Research Database (Denmark)

    Thorsteinsson, Sune; Poulsen, Peter Behrensdorff; Lindén, Johannes

    2014-01-01

    PV-powered lighting systems, light-to-light systems (L2L), offer outdoor lighting where it is else where cumbersome to enable lighting. Application of these systems at high latitudes, where the difference in day length between summer and winter is large and the solar energy is low requires smart...... dimming functions for reliable lighting. In this work we have built a laboratory to characterize these systems up to 200 Wp from “nose to tail” in great details to support improvement of the systems and to make accurate field performance predictions....

  20. Lumen Maintenance and Light Loss Factors: Consequences of Current Design Practices for LED's

    Energy Technology Data Exchange (ETDEWEB)

    Royer, Michael P.

    2013-09-17

    Synopsis: Light loss factors are used to help lighting systems meet quantitative design criteria throughout the life of the installation, but they also influence energy use. As the light sources currently being specified continue to evolve, it is necessary to reevaluate the methods used in calculating light loss factors, as well as carefully consider the consequences of different product performance attributes. Because of the unique operating characteristics of LEDs and lack of a comprehensive lifetime rating—as well as the problematic relationship between lifetime and lumen maintenance—determining an appropriate lamp lumen depreciation (LLD) factor for LED products is difficult. As a result, a unique solution has been advocated: when quantity of light is an important design consideration, the IES recommends using an LLD of not greater than 0.70. This method deviates from the typical practice for conventional sources of using the ratio of mean to initial lumen output, and can misrepresent actual performance, increase energy use, and inhibit comparisons between products. This paper discusses the complications related to LLD and LEDs, compares the performance of conventional and LED products, and examines alternatives to a maximum LLD of 0.70 for LEDs.

  1. "Light-box" accelerated growth of poinsettias: LED-only illumination

    Science.gov (United States)

    Weerasuriya, Charitha; Detez, Stewart; Hock Ng, Soon; Hughes, Andrew; Callaway, Michael; Harrison, Iain; Katkus, Tomas; Juodkazis, Saulius

    2018-01-01

    For the current commercialized agricultural industry which requires a reduced product lead time to customer and supply all year round, an artificial light emitting diodes (LEDs)-based illumination has high potential due to high efficiency of electrical-to-light conversion. The main advantage of the deployed Red Green Blue Amber LED lighting system is colour mixing capability, which means ability to generate all the colours in the spectrum by using three or four primary colours LEDs. The accelerated plant growth was carried out in a "light-box" which was made to generate an artificial day/night cycle by moving the colour mixing ratio along the colour temperature curve of the chromaticity diagram. The control group of plants form the same initial batch was grown on the same shelf in a greenhouse at the same conditions with addition of artificial illumination by incandescent lamps for few hours. Costs and efficiency projections of LED lamps for horticultural applications is discussed together with required capital investment. The total cost of the "light-box" including LED lamps and electronics was 850 AUD.

  2. Comparison of shear bond strength of stainless steel brackets bonded with three light- cured adhesives

    Directory of Open Access Journals (Sweden)

    Zahra Minaei Basharik

    2015-09-01

    Full Text Available Introduction: The bonding process of the brackets to enamel has been a critical issue in orthodontic research. The purpose of this study was to evaluate the shear bond strength of 3 light-cured adhesives (transbond XT, Z250, light bond. Materials &Methods: In this study sixty extracted human premolars were collected and randomly divided into 3 test groups. All teeth were etched by 37% phosphoric acid. In first group brackets were bonded by Transbond XT adhesive, in group two brackets were bonded by Light bond adhesive and in third group were bonded by filtek Z250 composite. All of them were cured with Ortholux xt for 40 seconds.24 hours after thermocycling, Shear Bond Strength (SBS values of these brackets were recorded using a Universal Testing Machine. Adhesive Remnant Index (ARI scores were determined after the failure of the brackets, using Stereo Microscope the data were analyzed using ANOVA and Chi-square tests. Results: Mean shear bond strength of Transbond XT, light bond and Z250 were 28.9±2.25 MPa, 25.06±1.98 MPa and 26.8±2.57 MPa, respectively. No significant difference was observed in the SBS among the groups and a clinically acceptable SBS was found for the three adhesives. ARI scores were not significantly different between the various groups (P>0.05. Conclusion: This study showed that the Z250 can be used as light bond and transbond xt to bond orthodontic brackets and ARI and SBS scores were not significantly different.

  3. Thermographic analysis of the effect of composite type, layering method, and curing light on the temperature rise of photo-cured composites in tooth cavities.

    Science.gov (United States)

    Kim, Min-Jung; Kim, Ryan Jin-Young; Ferracane, Jack; Lee, In-Bog

    2017-10-01

    The purpose of this study was to investigate temperature rise in the composite and dentin of a class I cavity in extracted human molars under different restoration conditions, including the use of different composite types, layering methods, and curing lights. Open occlusal cavities were prepared on 28 extracted human molars. A conventional (Filtek Z250) and a bulk-fill (Filtek Bulk Fill Posterior; BFP) composite were used to restore the preparations. BFP was incrementally layered or bulk-filled. Bulk-filled BFP was cured with two different lights, the Elipar S10 and the BeLite. Each layer was illuminated for 20s, while thermograms of the specimens were recorded for 100s using an infrared thermal camera. Temperature changes on the composite and dentin surfaces were obtained at points of interest (POI) pertaining to successive incremental distances of 0.75mm from the top of the cavity to the pulp. The polymerization kinetics of each composite was determined using photo-differential scanning calorimetry. The greatest temperature rise was observed 0.75mm apical from the top of the cavity. All groups showed over 6°C maximum temperature rise (ΔT max ) at the pulpal side of the dentin. Upon curing, Z250 reached ΔT=5°C faster than BFP; however, ΔT max of the two composites were comparable at any POI. Bulk filling showed greater ΔT max than incremental filling at 0.75mm apical from the top and in the middle of the cavity. The Elipar S10 light generated faster temperature changes in the curing composite at all recorded positions throughout the depth of the cavity and greater ΔT max in all POIs compared to BeLite. Real-time thermographic analysis demonstrated that the composite type and layering method did not influence the temperature rise at the pulpal side of dentin during composite restoration of an occlusal preparation in a tooth. The amount and initial rate of temperature increase was most affected by the radiant exposure of the light curing unit. Within the

  4. [Effects of different LED light qualities on growth, photosynthetic characteristics and nutritional quality of savoy].

    Science.gov (United States)

    Chen, Xiang-Wei; Liu, Shi-Qi; Wang, Yue; Liu, Jing-Kai; Feng, Lei

    2014-07-01

    LED lighting has several unique advantages over traditional lighting, including the ability to control spectral composition, the ability to produce very high light levels with low radiant heat output when cooled properly, and the ability to maintain useful light output for years without replacement. LED light sources have the capability of controlling true spectral composition, allowing wavelengths to match plant photoreceptors to provide more optimal production to regulate plant morphology and nutritional quality. In this paper, the effects of different light qualities on the growth, photosynthetic response and nutritional quality of savoy were studied. With 'Juhua-Xiaobaye' savoy as the test plant, full red light, full blue light, red/blue (3/1) light, red/blue (7/1) light and white/red/blue (3/2/1) light generated by light-emitting diodes were applied with white light generated by fluorescent lamps as control. The results showed that red light could increase biomass and stem diameter, but blue light showed the opposite effect. The chlorophyll (a+b) content was the highest in the red/blue (7/1) light treatment, and chlorophyll (a+b) content was correlated with the red/blue ratio positively. Blue light decreased chlorophyll (a + b) content of savoy, and increased chlorophyll a/b. The photosynthetic rate (Pn) and transpiration rate under red light were the highest, and increased by 43.8% and 55.1% compared with the control. Intercellular CO2 concentration and conductance were the highest under blue light. The fluorescence parameters of the plant were significantly affected by light quality. Values of the maximal photochemical efficiency of PS II (Fv/Fm), Fv/Fo and Phi(PS II) were the highest under white light. Soluble sugar, soluble protein and vitamin C contents were the highest under red, blue and white light, respectively. Comprehensive analysis indicated that red/blue (7/1) light was the best light combination to increase leaf chlorophyll (a+b) content and net

  5. Increase of energy efficiency in horticultural tissue culture with high-power-LED lighting systems; Energieeffizienzsteigerung pflanzlicher In-vitro-Kulturverfahren mit Hochleistungs-LED-Belichtungssystemen

    Energy Technology Data Exchange (ETDEWEB)

    Bornwasser, Thorsten

    2011-07-01

    The lighting of tissue cultures is one of the main cost factors in growing rooms due to the high energy need. A lighting system with high-power light-emitting diodes (HP-LEDs) was tested as an alternative to the conventionally used fluorescent tubes. Therefore the HP-LED-types royal-blue, red, and cool white were used to create different spectral outputs. The photon flux yield, level of efficiency, and spectral shift of the single HP-LEDs were measured beforehand at different operating conditions (i.e. increasing current and junction temperature). The energy efficiency of the HP-LED lighting system was determined at 0.83 {mu}mol W{sup -1}s{sup -1} with the same shelf board distance (300 mm) and average PPFD on the exposed surface as compared to the control lighting system. The energy efficiency of the fluorescent lighting system could reach a maximum value of 0.68 {mu}mol W{sup -1}s{sup -1}. In addition to the reduced energy needs, HP-LED lighting systems reduce the need for cooling energy in culture rooms to regulate the room temperature. HP-LED lighting systems allow the reduction of the shelf board distance due to the small mass volume of LEDs and diminished radiant heat output towards the plant. The lower shelf board distance led to an additional increase of the energy efficiency up to 1.16 {mu}mol W{sup -1}s{sup -1} at a distance of 210 mm. Simultaneously the PPFD distribution was more regular than under the exposure with a fluorescent tube. Beside the increase of energy efficiency, HP-LEDs facilitate the control of the spectral composition. The spectral output can be adjusted to the plants' needs and thereby permit a more optimal production and influence the plant morphology (Nhut und Na, 2010; Morrow, 2008). Various plant tissue cultures and their response to different spectral compositions were investigated with the developed HP-LED lighting system. For none of the tested cultures could a preference for one of the spectral compositions be determined

  6. How to distinguish scattered and absorbed light from re-emitted light for white LEDs?

    NARCIS (Netherlands)

    Meretska, Maryna; Lagendijk, Aart; Thyrrestrup Nielsen, Henri; Mosk, Allard; IJzerman, Wilbert; Vos, Willem L.

    2017-01-01

    We have studied the light transport through phosphor diffuser plates that are used in commercial solid-state lighting modules (Fortimo). These polymer plates contain YAG:Ce+3 phosphor particles that scatter, absorb and re-emit incident light in the visible wavelength range (400-700 nm). To

  7. Direct battery-driven solar LED lighting using constant-power control

    KAUST Repository

    Huang, Bin-Juine

    2012-11-01

    A direct battery-driven LED lighting technique using constant-power control is proposed in the present study. A system dynamics model of LED luminaire was derived and used in the design of the feedback constant-power control system. The test result has shown that the power of 18. W and 100. W LED luminaires can be controlled accurately with error at 2-5%. A solar LED street lighting system using constant-power and dimming control was designed and built for field test in a remote area. The long-term performance was satisfactory and no any failure since the installation. Since no high-power capacitor is used in the present constant-power control circuit, a longer lifetime is expected. © 2012 Elsevier Ltd.

  8. NASA sponsored Light Emitting Diode (LED) development helps in cancer treatment

    Science.gov (United States)

    1997-01-01

    What started out as an attempt to develop a light which would allow for the growth of plants in space led to a remarkable discovery: The Light Emitting Diode (LED). This device through extensive study and experimentation has developed into a tool used by surgeons in the fight against brain cancer in children. Pictured is a mock-up of brain surgery being performed. By encapsulating the end of the LED with a balloon, light is diffused over a larger area of the brain allowing the surgeon a better view. This is one of many programs that begin as research for the space program, and through extensive study end up benefitting all of mankind.

  9. Measurement of linear polymerization shrinkage in light cure Ideal Makoo composite resin

    Directory of Open Access Journals (Sweden)

    Ghavam M.

    2001-09-01

    Full Text Available "nAbstract: Polymerization shrinkage of light cure composite resins causes many complications in conservative and esthetic restorations. The objective of this in-vitro study was to evaluate the polymerization shrinkage, degree of conversion and the amount of filler in IDM and tetric ceram composites. Ten disk shaped, uncured specimens (8mm×1.547mm of each composite were placed on glass slide in the center of the metal attached to it. Then specimens were light cured for 60s from underneath. After 30 minutes, the thickness of specimens, using a micrometer and the percent of the polymerization shrinkage of each sample were measured. Statistical analysis was carried out by t-test (P<0.05. Also the degree of conversion of specimens was evaluated with FTIR and the mineral filler content was measured by burning in electric oven. Polymerization shrinkage in IDM and tetric ceram was not significantly different. Degree of conversion and mineral filler content in tetric ceram was greater than that of IDM. "nIt is assumed that the low degree of conversion in IDM is due to its chemical composition and filler content. Also, the similarity in linear polymerization shrinkage between IDM and tetric ceram may be caused by the low degree of conversion in IDM.

  10. Optimization of colour quality of LED lighting with reference to memory colours

    OpenAIRE

    Smet, Kevin; Ryckaert, Wouter; Pointer, Michael R.; Deconinck, Geert; Hanselaer, Peter

    2012-01-01

    Simulated and real tri- and tetrachromatic light-emitting-diode (LED) clusters were optimized for luminous efficacy of radiation (LER) and the memory colour quality metric developed by the authors. The simulated clusters showed no significant differences in achievable colour quality and LER between the different cluster types investigated. The real clusters (composed of commercially available LEDs) showed substantial differences in achievable colour quality and LER between the different clus...

  11. Innovations in LED lighting for reduced-ESM crop production in space

    Science.gov (United States)

    Massa, Gioia; Mitchell, Cary; Bourget, C. Michael; Morrow, Robert

    In controlled-environment crop production such as will be practiced at the lunar outpost and Mars base, the single most energy-demanding aspect is electric lighting for plant growth, including energy costs for energizing lamps as well as for removing excess heat. For a variety of reasons, sunlight may not be a viable option as the main source of crop lighting off-Earth and traditional electric lamps for crop lighting have numerous drawbacks for use in a space environment. A collaborative research venture between the Advanced Life Support Crops Group at Purdue University and the Orbital Technologies Corporation (ORBITEC) has led to the development of efficient, reconfigurable LED lighting technologies for crop growth in an ALSS. The light sources use printed-circuit red and blue LEDs, which are individually tunable for a range of photosynthetic photon fluxes and photomorphogenic plant responses. Initial lighting arrays have LEDs that can be energized from the bottom upward when deployed in a vertical, intracanopy configuration, allowing the illumination to be tailored for stand height throughout the cropping cycle. Preliminary testing with the planophile crop cowpea (Vigna unguiculata L. Walp, breeding line IT87D-941-1), resulted in optimizing internal reflectance of growth compartments by lining walls, floor, and a movable ceiling with white Poly film, as well as by determining optimal planting density and plant positioning. Additionally, these light strips, called "lightsicles", can be configured into an overhead plane of light engines. When intracanopy and overhead-LED-lit cowpea crop production was compared, cowpea plants grown with intracanopy lighting had much greater understory leaf retention and produced more dry biomass per kilowatt-hour of lighting energy than did overhead-lit plants. The efficiency of light capture is reduced in overhead-lit scenarios due to mutual shading of lower leaves by upper leaves in closed canopies leading to premature abscission

  12. Prototype of a new tip developed to be coupled to dental light-curing units for optimizing bonding of orthodontic brackets and accessories

    Directory of Open Access Journals (Sweden)

    Sergio Luiz Mota Júnior

    2013-12-01

    Full Text Available OBJECTIVE: development of a new device to be coupled to light-curing units for bonding orthodontic brackets and accessories, and test its efficacy in an in vitro mechanical trial. The inner surface of the device is mirrored and is based on physical concepts of light refraction and reflection. The main advantage of such device is the reduced clinical time needed for bonding and the low possibility of contamination during the process. METHODS: One hundred and twenty specimens were used for testing the shear bond strength of brackets bonded with the device. The Adhesive Remnant Index (ARI was also determined. The sample was divided into 2 groups. In group 1 a halogen light-curing unit was used while in group 2 a led light-curing unit was used. Each group was then subdivided. In subgroups H1 and L1, a conventional light guide rod was used while in subgroups H2 and L2 bonding was performed with the mirrored device coupled to the tip of the guide light rod. RESULTS: The values obtained for the shear bond strength and the ARI in the subgroups were compared. Results showed that there was no statistically significant difference for the shear strength (p > 0.05 and the ARI (p > 0.05 between the subgroups. CONCLUSION: The tests of mechanical trials and the ARI analysis showed that the new device fulfilled the requirements for bonding orthodontic accessories, and that the time for bonding was reduced to half, being necessary only one light exposure.

  13. Multi-channel LED light source for fluorescent agent aided minimally invasive surgery.

    Science.gov (United States)

    Ren, Jiacheng; Venugopalan, Janani; Xu, Jian; Kairdolf, Brad; Durfee, Robert; Wang, May D

    2014-01-01

    Cancer is one of the most common and deadly diseases around the world. Amongst all the different treatments of cancer such as surgery, chemotherapy and radiation therapy, surgical resection is the most effective. Successful surgeries greatly rely on the detection of the accurate tumor size and location, which can be enhanced by contrast agents. Commercial endoscope light sources, however, offer only white light illumination. In this paper, we present the development of a LED endoscope light source that provides 2 light channels plus white light to help surgeons to detect a clear tumor margin during minimally invasive surgeries. By exciting indocyanine green (ICG) and 5-Aminolaevulinic acid (ALA)-induced protoporphyrin IX (PPIX), the light source is intended to give the user a visible image of the tumor margin. This light source is also portable, easy to use and costs less than $300 to build.

  14. LED light attenuation through human dentin: a first step toward pulp photobiomodulation after cavity preparation.

    Science.gov (United States)

    Turrioni, Ana Paula S; Alonso, Juliana R L; Basso, Fernanda G; Moriyama, Lilian T; Hebling, Josimeri; Bagnato, Vanderlei S; De Souza, Costa Carlos A

    2013-12-01

    To evaluate the transdentinal light attenuation of LED at three wavelengths through different dentin thicknesses, simulating cavity preparations of different depths. Forty-two dentin discs of three thicknesses (0.2, 0.5 and 1 mm; n = 14) were prepared from the coronal dentin of extracted sound human molars. The discs were illuminated with a LED light at three wavelengths (450+/-10 nm, 630 +/-10 nm and 850 +/-10 nm) to determine light attenuation. Light transmittance was also measured by spectrophotometry. In terms of minimum (0.2 mm) and maximum (1.0 mm) dentin thicknesses, the percentage of light attenuation varied from 49.3% to 69.9% for blue light, 42.9% to 58.5% for red light and 39.3% to 46.8% for infrared. For transmittance values, an increase was observed for all thicknesses according to greater wavelengths, and the largest variation occurred for the 0.2 mm thickness. All three wavelengths were able to pass through the dentin barrier at different thicknesses. Furthermore, the LED power loss and transmittance showed wide variations, depending on dentin thickness and wavelength.

  15. A calibrated UV-LED based light source for water purification and characterisation of photocatalysis.

    Science.gov (United States)

    Sergejevs, A; Clarke, C T; Allsopp, D W E; Marugan, J; Jaroenworaluck, A; Singhapong, W; Manpetch, P; Timmers, R; Casado, C; Bowen, C R

    2017-11-08

    Photocatalysis has a potential to become a cost effective industrial process for water cleaning. One of the most studied photocatalysts is titanium dioxide which, as a wide band gap semiconductor, requires ultraviolet (UV) light for its photoactivation. This is at the wavelengths where the efficiency of present-day light emitting diodes (LEDs) decreases rapidly, which presents a challenge in the use of UV-LEDs for commercially viable photocatalysis. There is also a need for accurate photocatalysis measurement of remediation rates of water-borne contaminants for determining optimum exposure doses in industrial applications. In response to these challenges, this paper describes a UV-LED based photocatalytic test reactor that provides a calibrated adjustable light source and pre-defined test conditions to remove as many sources of uncertainty in photocatalytic analysis as possible and thereby improve data reliability. The test reactor provides a selectable intensity of up to 1.9 kW m -2 at the photocatalyst surface. The comparability of the results is achieved through the use of pre-calibration and control electronics that minimize the largest sources of uncertainty; most notably variations in the intensity and directionality of the UV light emission of LEDs and in LED device heating.

  16. Smart LED allocation scheme for efficient multiuser visible light communication networks.

    Science.gov (United States)

    Sewaiwar, Atul; Tiwari, Samrat Vikramaditya; Chung, Yeon Ho

    2015-05-18

    In a multiuser bidirectional visible light communication (VLC), a large number of LEDs or an LED array needs to be allocated in an efficient manner to ensure sustainable data rate and link quality. Moreover, in order to support an increasing or decreasing number of users in the network, the LED allocation is required to be performed dynamically. In this paper, a novel smart LED allocation scheme for efficient multiuser VLC networks is presented. The proposed scheme allocates RGB LEDs to multiple users in a dynamic and efficient fashion, while satisfying illumination requirements in an indoor environment. The smart LED array comprised of RGB LEDs is divided into sectors according to the location of the users. The allocated sectors then provide optical power concentration toward the users for efficient and reliable data transmission. An algorithm for the dynamic allocation of the LEDs is also presented. To verify its effective resource allocation feature of the proposed scheme, simulations were performed. It is found that the proposed smart LED allocation scheme provides the effect of optical beamforming toward individual users, thereby increasing the collective power concentration of the optical signals on the desirable users and resulting in significantly increased data rate, while ensuring sufficient illumination in a multiuser VLC environment.

  17. Tradeoff between laser diodes and light-emitting diodes (LEDs) for the common weapon control system

    Science.gov (United States)

    Greenwell, R. A.

    1982-07-01

    The use of laser diodes or light emitting diodes (LEDs) for the ground-launched cruise missile (GLCM) is comparatively evaluated. Source characteristics of interest, including radiated power output, spectral width and peak emission, modulation bandwidth, size coupling efficiency, lifetime, rise time, and price, are presented for noncoherent LED and the coherent laser diode. The advantages and disadvantages of laser diodes and LEDs are briefly discussed, and nuclear explosion effects on these instruments, including catastrophic damage, transient ionization effects, and permanent degradation, are summarized. A link analysis of the cable parameters required for the GLCM fiber optic data link is given, arriving at power levels consistent with a LED-PIN link. Two LEDs which meet these requirements are briefly discussed.

  18. Deep Ultraviolet Light Emitting Diode (LED)-Based Sensing of Sulfur Dioxide.

    Science.gov (United States)

    Michel, Anna P M; Kapit, Jason

    2017-05-01

    With the recent development of deep ultraviolet (DUV) light emitting diodes (LEDs) comes the possibility of targeting absorption bands of several gases, including sulfur dioxide (SO 2 ). SO 2 has strong absorption bands in the 300 nm spectral region. The low cost and small size of DUV LEDs, coupled with their spectral coverage, makes them viable sources for new gas sensors. Here, we demonstrate the capability to use absorption spectroscopy with a balanced detection scheme using a 300 nm DUV LED source for SO 2 detection at concentrations ranging from less than 1 ppm to 50 ppm.

  19. Influence of cavity preparation, light-curing units, and composite filling on intrapulpal temperature increase in an in vitro tooth model.

    Science.gov (United States)

    Choi, S H; Roulet, J F; Heintze, S D; Park, S H

    2014-01-01

    This study examined the effect of both the tooth substance and restorative filling materials on the increase in pulp chamber temperature when using light-curing units with different power densities. The tip of a temperature sensor was positioned on the pulpal dentinal wall of the buccal side of a maxillary premolar. Metal tubes were inserted in the palatal and buccal root of the tooth, one for water inflow and the other for water outflow. Polyethylene tubes were connected from the metal tubes to a pump to control the flow rate. For the unprepared tooth group (group 1), the tooth was light-cured from the buccal side using two light-curing units (three curing modes): the VIP Junior (QTH, BISCO, Schaumburg, IL, USA) and the Bluephase LED light-curing units (two modes: LEDlow and LEDhigh; Ivoclar Vivadent, Schaan, Liechtenstein). The power densities of each light-curing unit for the LEDlow, QTH, and LEDhigh modes were 785 mW/cm(2), 891 mW/cm(2), and 1447 mW/cm(2), respectively. All light-curing units were activated for 60 seconds. For the prepared tooth group (group 2), a Class V cavity, 4.0 mm in width by 4.0 mm in height by 1.8 mm in depth in size, was prepared on the buccal surface of the same tooth for the temperature measurement. The light-curing and temperature measurements were performed using the same methods used in group 1. The cavity prepared in group 2 was filled with a resin composite (Tetric N Ceram A3 shade, Ivoclar Vivadent) (group 3) or a flowable composite (Tetric N Flow with A3 shade, Ivoclar Vivadent) (group 4). The light-curing and temperature measurements were performed for these groups using the same methods used for the other groups. The highest intrapulpal temperature (TMAX) was measured, and a comparison was conducted between the groups using two-way analysis of variance with a post hoc Tukey test at the 95% confidence level. The TMAX values were as follows: 38.4°C (group 1), 39.0°C (group 2), 39.8°C (group 3), and 40.3°C (group 4) for the

  20. Study of system dynamics model and control of a high-power LED lighting luminaire

    International Nuclear Information System (INIS)

    Huang, B.-J.; Hsu, P.-C.; Wu, M.-S.; Tang, C.-W.

    2007-01-01

    The purpose of the present study is to design a current control system which is robust to the system dynamics uncertainty and the disturbance of ambient temperature to assure a stable optical output property of LED. The system dynamics model of the LED lighting system was first derived. A 96 W high-power LED luminaire was designed and built in the present study. The linearly perturbed system dynamics model for the LED luminaire is derived experimentally. The dynamics model of LED lighting system is of a multiple-input-multiple-output (MIMO) system with two inputs (applied voltage and ambient temperature) and two outputs (forward current and heat conducting body temperature). A step response test method was employed to the 96 W LED luminaire to identify the system dynamics model. It is found that the current model is just a constant gain (resistance) and the disturbance model is of first order, both changing with operating conditions (voltage and ambient temperature). A feedback control system using PI algorithm was designed using the results of the system dynamics model. The control system was implemented on a PIC microprocessor. Experimental results show that the control system can stably and accurately control the LED current to a constant value at the variation of ambient temperature up to 40 o C. The control system is shown to have a robust property with respect to the plant uncertainty and the ambient temperature disturbance

  1. GATEWAY Demonstrations: Tuning Hospital Lighting: Evaluating Tunable LED Lighting at the Swedish Hospital Behavioral Health Unit in Seattle

    Energy Technology Data Exchange (ETDEWEB)

    Wilkerson, Andrea [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Davis, Robert G. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Clark, Edward [ZGF Architects LLP, Seattle, WA (United States)

    2017-08-23

    The GATEWAY program evaluated a tunable LED lighting system installed in the new Swedish Medical Behavioral Health Unit in Seattle that incorporates color-tunable luminaires in common areas, and uses advanced controls for dimming and color tuning, with the goal of providing a better environment for staff and patients. The report reviews the design of the tunable lighting system, summarizes two sets of measurements, and discusses the circadian, energy, and commissioning implications as well as lessons learned from the project.

  2. Is light-emitting diode phototherapy (LED-LLLT) really effective?

    Science.gov (United States)

    Kim, Won-Serk; Calderhead, R Glen

    2011-01-01

    Low level light therapy (LLLT) has attracted attention in many clinical fields with a new generation of light-emitting diodes (LEDs) which can irradiate large targets. To pain control, the first main application of LLLT, have been added LED-LLLT in the accelerated healing of wounds, both traumatic and iatrogenic, inflammatory acne and the patient-driven application of skin rejuvenation. Rationale and Applications: The rationale behind LED-LLLT is underpinned by the reported efficacy of LED-LLLT at a cellular and subcellular level, particularly for the 633 nm and 830 nm wavelengths, and evidence for this is presented. Improved blood flow and neovascularization are associated with 830 nm. A large variety of cytokines, chemokines and macromolecules can be induced by LED phototherapy. Among the clinical applications, non-healing wounds can be healed through restoring the collagenesis/collagenase imbalance in such examples, and 'normal' wounds heal faster and better. Pain, including postoperative pain, postoperative edema and many types of inflammation can be significantly reduced. Experimental and clinical evidence: Some personal examples of evidence are offered by the first author, including controlled animal models demonstrating the systemic effect of 830 nm LED-LLLT on wound healing and on induced inflammation. Human patients are presented to illustrate the efficacy of LED phototherapy on treatment-resistant inflammatory disorders. Provided an LED phototherapy system has the correct wavelength for the target cells, delivers an appropriate power density and an adequate energy density, then it will be at least partly, if not significantly, effective. The use of LED-LLLT as an adjunct to conventional surgical or nonsurgical indications is an even more exciting prospect. LED-LLLT is here to stay.

  3. Study on Ultraviolet Light Cured Resin Bond Grind/Lap for Aluminum Oxide Ceramics

    Science.gov (United States)

    Huang, Qiuyun

    After the development of ultraviolet (UV) curing technology, a novel method to manufacture abrasive tools using UV light curing technique was proposed. After decades of research activities, the UV-cured resin bond tools have been studied and proven to have substantial advantages. However, very little research has been done to study the mechanism of such abrasive tools. In this study, the mechanism of UV-cured resin bond diamond tools was proposed as a Grind/Lap (G/L) process and an experimental method was used to verify the mechanism. Furthermore, the models of surface roughness (RA) and material removal rate (MRR) in the process of ceramics have been intensively investigated. The traditional way to fabricate abrasive tools is by utilizing the thermosetting method. The mixture of abrasives and bond material is sintered at high temperature under extremely high pressure, and it is a time consuming and costly procedure. However, for the UV-curing technique, after being exposed to UV light with a certain intensity, the abrasive-mixed resin can be solidified in a short time. The process is environmentally friendly and has strong productivity advantages but coupled with low energy consumption. The purpose of this research is to understand fundamental issues in UV-curable resin and face grinding of ceramic materials using UV-cured resin bond wheels, including to study the kinematics of face grinding (grinding with lapping kinematics) and the properties of UV-cured abrasive-mixed resin, verify the mechanism proposed for grind/lap process and investigate the effects of several factors on the performance of UV-cured resin bond wheel for aluminum oxide ceramics. The kinematic relation between the workpiece, workpiece holder and the wheel were investigated. The trajectories generated under different speed combinations were simulated. Based on the trace distribution, a combination of the speed of wheel and holder can be suggested and an explanation of interactional effect of

  4. Degree of conversion of a resin cement light-cured through ceramic veneers of different thicknesses and types.

    Science.gov (United States)

    Runnacles, Patrício; Correr, Gisele Maria; Baratto Filho, Flares; Gonzaga, Carla Castiglia; Furuse, Adilson Yoshio

    2014-01-01

    During the cementation of ceramic veneers the polymerization of resin cements may be jeopardized if the ceramics attenuate the irradiance of the light-curing device. The aim of this study was to evaluate the effect of different types and thicknesses of ceramic veneers on the degree of conversion of a light-cured resin-based cement (RelyX Veneer). The cement was light-cured after interposing ceramic veneers [IPS InLine, IPS Empress Esthetic, IPS e.max LT (low translucency) and IPS e.max HT (high translucency) - Ivoclar Vivadent] of four thicknesses (0.5 mm, 1.0 mm, 1.5 mm and 2.0 mm). As control, the cement was light-cured without interposition of ceramics. The degree of conversion was evaluated by FTIR spectroscopy (n=5). Data were analyzed with one-way ANOVA and Tukey's test (α=0.05). Significant differences were observed among groups (pceramics of 0.5 mm and 1.0 mm (p>0.05). Among 1.5-mm-thick veneers, IPS e.max LT was the only one that showed different results from the control (p0.05). The degree of conversion of the evaluated light-cured resin cement depends on the thickness and type of ceramics employed when veneers thicker than 1.5 mm are cemented.

  5. LED Light Source for in vitro Study of Photosensitizing Agents for Photodynamic Therapy

    OpenAIRE

    N.Y. Shilyagina; V.I. Plekhanov; I.V. Shkunov; P.А. Shilyagin; L.V. Dubasova; А.А. Brilkina; Е.А. Sokolova; I.V. Turchin; I.V. Balalaeva

    2014-01-01

    The aim of the investigation was to develop a LED light source providing a homogeneous light distribution in 96-well plates and allowing an independent irradiation of individual wells, as well as its experimental testing in in vitro study of photosensitizers for photodynamic therapy. Materials and Methods. The experiments were carried out on human cell lines of epidermoid carcinoma А-431 and human bladder carcinoma Т24. Two photosensitizers for fluorescence diagnostics and photodynamic th...

  6. Slim planar apparatus for converting LED light into collimated polarized light uniformly emitted from its top surface.

    Science.gov (United States)

    Teng, Tun-Chien; Tseng, Li-Wei

    2014-10-20

    This study proposes a slim planar apparatus for converting nonpolarized light from a light-emitting diode (LED) into an ultra-collimated linearly polarized beam uniformly emitted from its top surface. The apparatus was designed based on a folded-bilayer configuration comprising a light-mixing collimation element, polarization conversion element, and polarization-preserving light guide plate (PPLGP) with an overall thickness of 5 mm. Moreover, the apparatus can be extended transversally by connecting multiple light-mixing collimation elements and polarization conversion elements in a side-by-side configuration to share a considerably wider PPLGP, so the apparatus can have theoretically unlimited width. The simulation results indicate that the proposed apparatus is feasible for the maximal backlight modules in 39-inch liquid crystal panels. In the case of an apparatus with a 480 × 80 mm emission area and two 8-lumen LED light sources, the average head-on polarized luminance and spatial uniformity over the emission area was 5000 nit and 83%, respectively; the vertical and transverse angular distributions of the emitting light were only 5° and 10°, respectively. Moreover, the average degree of polarization and energy efficiency of the apparatus were 82% and 72%, respectively. As compared with the high-performance ultra-collimated nonpolarized backlight module proposed in our prior work, not only did the apparatus exhibit outstanding optical performance, but also the highly polarized light emissions actually increased the energy efficiency by 100%.

  7. Development of Advanced LED Phosphors by Spray-based Processes for Solid State Lighting

    Energy Technology Data Exchange (ETDEWEB)

    Cabot Corporation

    2007-09-30

    The overarching goal of the project was to develop luminescent materials using aerosol processes for making improved LED devices for solid state lighting. In essence this means improving white light emitting phosphor based LEDs by improvement of the phosphor and phosphor layer. The structure of these types of light sources, displayed in Figure 1, comprises of a blue or UV LED under a phosphor layer that converts the blue or UV light to a broad visible (white) light. Traditionally, this is done with a blue emitting diode combined with a blue absorbing, broadly yellow emitting phosphor such as Y{sub 3}Al{sub 5}O{sub 12}:Ce (YAG). A similar result may be achieved by combining a UV emitting diode and at least three different UV absorbing phosphors: red, green, and blue emitting. These emitted colors mix to make white light. The efficiency of these LEDs is based on the combined efficiency of the LED, phosphor, and the interaction between the two. The Cabot SSL project attempted to improve the over all efficiency of the LED light source be improving the efficiency of the phosphor and the interaction between the LED light and the phosphor. Cabot's spray based process for producing phosphor powders is able to improve the brightness of the powder itself by increasing the activator (the species that emits the light) concentration without adverse quenching effects compared to conventional synthesis. This will allow less phosphor powder to be used, and will decrease the cost of the light source; thus lowering the barrier of entry to the lighting market. Cabot's process also allows for chemical flexibility of the phosphor particles, which may result in tunable emission spectra and so light sources with improved color rendering. Another benefit of Cabot's process is the resulting spherical morphology of the particles. Less light scattering results when spherical particles are used in the phosphor layer (Figure 1) compared to when conventional, irregular shaped

  8. White LED compared with other light sources: age-dependent photobiological effects and parameters for evaluation.

    Science.gov (United States)

    Rebec, Katja Malovrh; Klanjšek-Gunde, Marta; Bizjak, Grega; Kobav, Matej B

    2015-01-01

    Ergonomic science at work and living places should appraise human factors concerning the photobiological effects of lighting. Thorough knowledge on this subject has been gained in the past; however, few attempts have been made to propose suitable evaluation parameters. The blue light hazard and its influence on melatonin secretion in age-dependent observers is considered in this paper and parameters for its evaluation are proposed. New parameters were applied to analyse the effects of white light-emitting diode (LED) light sources and to compare them with the currently applied light sources. The photobiological effects of light sources with the same illuminance but different spectral power distribution were determined for healthy 4-76-year-old observers. The suitability of new parameters is discussed. Correlated colour temperature, the only parameter currently used to assess photobiological effects, is evaluated and compared to new parameters.

  9. Effect of different light curing methods on mechanical and physical properties of resin-cements polymerized through ceramic discs.

    Science.gov (United States)

    Cekic-Nagas, Isil; Ergun, Gulfem

    2011-08-01

    The aim of this study was to compare the polimerization ability of three different light-curing units (quartz tungsten halogen, light-emitting diodes and plasma arc) and their exposure modes (high-intensity and soft-start) by determination of microhardness, water sorption and solubility, and diametral tensile strength of 5 dual-curing resin cements. A total of 720 disc-shaped samples (1 mm height and 5 mm diameter) were prepared from different dual-curing resin cements (Duolink, Nexus, Bifix-QM, Panavia F and RelyX Unicem). Photoactivation was performed by using quartz tungsten halogen (high-power and soft-up modes), light-emitting diode (standard and exponential modes) and plasma arc (normal and ramp-curing modes) curing units through ceramic discs. Then the samples (n=8/per group) were stored dry in the dark at 37°C for 24 h. The Vickers hardness test was performed on the resin cement layer with a microhardness tester (Shimadzu HMV). For sorption and solubility tests; the samples were stored in a desiccator at 37°C and weighed to a constant mass. The samples were weighed both before and after being immersed in deionized water for different periods of time (24 h and 7 days) and being desiccated. The diametral tensile strength of the samples was tested in a universal testing machine at a crosshead speed of 0.5 mm/min. Data were analyzed statistically by nonparametric Kruskal Wallis and Mann-Whitney U tests at 5% significance level. Resin cement and light-curing unit had significant effects (p0.05) were obtained with different modes of LCUs. The study indicates that polymerization of resin cements with different light-curing units may result in various polymer structures, and consequently different mechanical and physical properties.

  10. Effect of different light curing methods on mechanical and physical properties of resin-cements polymerized through ceramic discs

    Directory of Open Access Journals (Sweden)

    Isil Cekic-nagas

    2011-08-01

    Full Text Available OBJECTIVE: The aim of this study was to compare the polimerization ability of three different light-curing units (quartz tungsten halogen, light-emitting diodes and plasma arc and their exposure modes (high-intensity and soft-start by determination of microhardness, water sorption and solubility, and diametral tensile strength of 5 dual-curing resin cements. Material and methods: A total of 720 disc-shaped samples (1 mm height and 5 mm diameter were prepared from different dual-curing resin cements (Duolink, Nexus, Bifix-QM, Panavia F and RelyX Unicem. Photoactivation was performed by using quartz tungsten halogen (high-power and soft-up modes, light-emitting diode (standard and exponential modes and plasma arc (normal and ramp-curing modes curing units through ceramic discs. Then the samples (n=8/per group were stored dry in the dark at 37°C for 24 h. The Vickers hardness test was performed on the resin cement layer with a microhardness tester (Shimadzu HMV. For sorption and solubility tests; the samples were stored in a desiccator at 37°C and weighed to a constant mass. The samples were weighed both before and after being immersed in deionized water for different periods of time (24 h and 7 days and being desiccated. The diametral tensile strength of the samples was tested in a universal testing machine at a crosshead speed of 0.5 mm/min. Data were analyzed statistically by nonparametric Kruskal Wallis and Mann-Whitney U tests at 5% significance level. RESULTS: Resin cement and light-curing unit had significant effects (p0.05 were obtained with different modes of LCUs. Conclusion: The study indicates that polymerization of resin cements with different light-curing units may result in various polymer structures, and consequently different mechanical and physical properties.

  11. Effect of Fast Curing Lights, Argon Laser, and Plasma Arc on Bond Strengths of Orthodontic Brackets: An In Vitro Study

    Directory of Open Access Journals (Sweden)

    M. Hashem-Hoseini

    2008-12-01

    Full Text Available Objective: Nowadays light-cured composites are used widely by orthodontists to bond brackets. As these composites require 20-40 seconds time per tooth to be light cured, more chair-time in needed compared to self-cured composites. In recent years, the argon laser and plasma arc lights have been introduced in dentistry to reduce this curing time. The purpose of this study was to compare bond strength of brackets bonded with the argon la-ser and plasma arc light with those bonded with the conventional halogen light.Materials and Methods: Fifty-one intact human premolars were randomly divided into three groups of 17 teeth each. Stainless steel twin premolar brackets (018- in Dyna lock, 3M Unitek were bonded to the teeth using one of these curing devices in each group: the halogen unit (Coltolux 75, Switzerland, the argon laser unit (Bo-5, Iran , and the plasma arc unit (Remecure 15, Belgium. The orthodontic adhesive was the same in the three groups (Transbond XT, 3M Unitek. After thermal cycling, the diametral tensilebond strength of specimens was measured using a debonding plier in a Zwick Universal Testing machine (Z/100, Germany.Results: The mean bond strengths was 17.344 MPa (SD=4.567 for halogen 19.172 MPa(SD=6.328 for laser and 19.322 MPa (SD=4.036 for plasma arc groups. No statistically significant difference existed in the mean bond strengths among three groups.Conclusion: Argon laser lights, significantly reducing the curing time of orthodonticbrackets without affecting bond strength, have the potential to be considered as advanta-geous alternatives to conventional halogen light.

  12. Demonstration Assessment of Light-Emitting Diode (LED) Roadway Lighting at the I-35W Bridge, Minneapolis, MN

    Energy Technology Data Exchange (ETDEWEB)

    Kinzey, Bruce R.; Myer, Michael

    2009-08-31

    This report describes the process and results of a demonstration of solid-state lighting (SSL) technology conducted in 2009 at the recently reconstructed I-35W bridge in Minneapolis, MN. The project was supported under the U.S. Department of Energy (DOE) Solid-State Lighting GATEWAY Technology Demonstration Program. Other participants in the demonstration project included the Minnesota Department of Transportation (Mn/DOT), Federal Highways Administration (FHWA), and BetaLED™ (a division of Ruud Lighting). Pacific Northwest National Laboratory (PNNL) conducted the measurements and analysis of the results. DOE has implemented a three-year evaluation of the LED luminaires in this installation in order to develop new longitudinal field data on LED performance in a challenging, real-world environment. This document provides information through the initial phase of the I-35W bridge project, up to and including the opening of the bridge to the public and the initial feedback received on the LED lighting installation from bridge users. Initial findings of the evaluation are favorable, with minimum energy savings level of 13% for the LED installation relative to the simulated base case using 250W high-pressure sodium (HPS) fixtures. The LEDs had an average illuminance level of 0.91 foot candles compared to 1.29 fc for the HPS lamps. The LED luminaires cost $38,000 more than HPS lamps, yielding a lengthy payback period, however the bridge contractor had offered to include the LED luminaires as part of the construction package at no additional cost. One potentially significant benefit of the LEDs in this installation is avoiding rolling lane closures on the heavily-traveled interstate bridge for the purpose of relamping the HPS fixtures. Rolling lane closures involve multiple crew members and various maintenance and safety vehicles, diversion of traffic, as well as related administrative tasks (e.g., approvals, scheduling, etc.). Mn/DOT records show an average cost of

  13. High-Bandwidth White-Light System Combining a Micro-LED with Perovskite Quantum Dots for Visible Light Communication.

    Science.gov (United States)

    Mei, Shiliang; Liu, Xiaoyan; Zhang, Wanlu; Liu, Ran; Zheng, Lirong; Guo, Ruiqian; Tian, Pengfei

    2018-02-14

    This work proposes a high-bandwidth white-light system consisting of a blue gallium nitride (GaN) micro-LEDLED) exciting yellow-emitting CsPbBr 1.8 I 1.2 perovskite quantum dots (YQDs) for high-speed real-time visible light communication (VLC). The packaged 80 μm × 80 μm blue-emitting μLED has a modulation bandwidth of ∼160 MHz and a peak emission wavelength of ∼445 nm. The achievable bandwidth of the white-light system is up to 85 MHz in the absence of filters and equalization technology. Meanwhile, the bandwidth of the YQDs as a color converter is as high as 73 MHz with the blue GaN μLED as the pump source. A maximum data rate of 300 Mbps can be achieved by taking advantage of the high bandwidth of the white-light system using the non-return-to-zero on-off keying (NRZ-OOK) modulation scheme. The resultant bit-error rate is 2.0 × 10 -3 , well beneath the forward error correction criterion of 3.8 × 10 -3 required for error-free data transmission. In addition, the YQDs which we proposed as a color converter possess high stability for VLC. After half a year, the achievable bandwidths of the white-light system and the YQDs are still up to 83 and 70 MHz, respectively. This study provides the direction of developing high-bandwidth white-light system for both high-efficiency solid-state lighting and high-speed VLC.

  14. LED light stress induced biomass and fatty acid production in microalgal biosystem, Acutodesmus obliquus.

    Science.gov (United States)

    Choi, Yong-Keun; Kumaran, Rangarajulu Senthil; Jeon, Hyeon Jin; Song, Hak-Jin; Yang, Yung-Hun; Lee, Sang Hyun; Song, Kyung-Guen; Kim, Kwang Jin; Singh, Vijay; Kim, Hyung Joo

    2015-06-15

    Microbial algal system can serve as a potential source for the production of much high value bioproducts and biofuels. The quality and intensity of light are the key elements to optimize the production of algal biomass and fatty acid contents. This study presents the effect of differential LED flashing light conditions on the growth of microalgae, Acutodesmus obliquus. The induced light stress was optimized for its biomass and fatty acid content. The microalgae are exposed to various frequency of intermittent LED flashing light (blue and red lights) at three different phases in the 18 day cell growth (log, lag and stationary phase). The frequency of light flashing rate was adjusted to 120, 10, 5, 3.75, and 1 times per min. The effect of light stress on growth and fatty acids composition of A. obliquus induced an increase in algae growth and fatty acid production. Different optimal timing for light stress was subjected to elucidate the effect of light stress on algae growth and fatty acid production. The results showed an increase in the algae growth (1.2mg/L of chl a content) under light stress condition at FT10 (flashing time, 10 times per min) from the initial day (log phase) compared with the control experiment (0.4 mg/L of chl a content). However, the total fatty acids (71 mg/g) and volumetric FAME production (9.4 ml/l) level was found to be significant under FT5 (flashing time, 5 times per min), adopting flashing light from day 10 (stationary phase). TEM studies also revealed the deposition of lipid to be largest in the 18 day old cells under flashing light (FT5) condition, representing maximum accumulation of lipids bodies (up to 770 nm diameter in particle size) occupying approximately 42% of the total area of the cell. Copyright © 2015 Elsevier B.V. All rights reserved.

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

    Directory of Open Access Journals (Sweden)

    Kenitz J Dustin

    2005-08-01

    Full Text Available Abstract Background Although specific light attributes, such as color and fluence rate, influence plant growth and development, researchers generally cannot control the fine spectral conditions of artificial plant-growth environments. Plant growth chambers are typically outfitted with fluorescent and/or incandescent fixtures that provide a general spectrum that is accommodating to the human eye and not necessarily supportive to plant development. Many studies over the last several decades, primarily in Arabidopsis thaliana, have clearly shown that variation in light quantity, quality and photoperiod can be manipulated to affect growth and control develop