The Experts below are selected from a list of 114 Experts worldwide ranked by ideXlab platform
J L Lean - One of the best experts on this subject based on the ideXlab platform.
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a new lower Value of total solar Irradiance evidence and climate significance
Geophysical Research Letters, 2011Co-Authors: Greg Kopp, J L LeanAbstract:[1] The most accurate Value of total solar Irradiance during the 2008 solar minimum period is 1360.8 ± 0.5 W m−2 according to measurements from the Total Irradiance Monitor (TIM) on NASA's Solar Radiation and Climate Experiment (SORCE) and a series of new radiometric laboratory tests. This Value is significantly lower than the canonical Value of 1365.4 ± 1.3 W m−2 established in the 1990s, which energy balance calculations and climate models currently use. Scattered light is a primary cause of the higher Irradiance Values measured by the earlier generation of solar radiometers in which the precision aperture defining the measured solar beam is located behind a larger, view-limiting aperture. In the TIM, the opposite order of these apertures precludes this spurious signal by limiting the light entering the instrument. We assess the accuracy and stability of Irradiance measurements made since 1978 and the implications of instrument uncertainties and instabilities for climate research in comparison with the new TIM data. TIM's lower solar Irradiance Value is not a change in the Sun's output, whose variations it detects with stability comparable or superior to prior measurements; instead, its significance is in advancing the capability of monitoring solar Irradiance variations on climate-relevant time scales and in improving estimates of Earth energy balance, which the Sun initiates.
Maan M Alshaafi - One of the best experts on this subject based on the ideXlab platform.
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Effects of different infection control methods on the intensity output of {LED} Light-Curing Units
King Saud University Journal of Dental Sciences, 2013Co-Authors: Maan M AlshaafiAbstract:Objective To evaluate the effect of two different infection control techniques on the Irradiance Value output of {LED} curing units. Methods Two different infection control techniques were involved in this investigation: (1) autoclaving and (2) disinfectant with a clear barrier. A high-power {LED} (Elipar S10, 3 M, Neuss, Germany) was used as the curing unit. Light Irradiance Values (mW/cm2) of each light tip were measured by a calibrated spectral device (PS-MARC [Patient Simulator-Managing Accurate Resin Curing] BlueLight Analytic Inc., Halifax, Nova Scotia, Canada). For each group, 5 new curing tips were involved and a total of 25 cycles were performed. For the autoclave group, each of the 5 curing tips was sterilized with an autoclave cycle (15 min). In the second group, the 5 tested tips were wiped with a disinfectant solution (MinutenSpray, {APMD} GmbH, Munich, Germany) and then covered with a clear commercial disposable barrier (Disposa-Shield, Dentsply, USA). The statistical analysis involved using the t-test and the Tukey test. Results Analysis of the data showed reductions of Irradiance Values in both groups compared with the baseline Values. The group with autoclaved curing tips had a lower Value compared with the disinfectant/barrier tips group. There were statistically significant differences between the tested groups (P < 0.05). Conclusion The quality of the tested {LCU} was reduced when either of the above infection control techniques was used. Clinicians are recommended to monitor their {LCU} by applying the same infection control methods on light tips when testing its Irradiance Value.
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Effects of different infection control methods on the intensity output of LED Light-Curing Units ☆
King Saud University Journal of Dental Sciences, 2013Co-Authors: Maan M AlshaafiAbstract:Abstract Objective To evaluate the effect of two different infection control techniques on the Irradiance Value output of LED curing units. Methods Two different infection control techniques were involved in this investigation: (1) autoclaving and (2) disinfectant with a clear barrier. A high-power LED (Elipar S10, 3 M, Neuss, Germany) was used as the curing unit. Light Irradiance Values (mW/cm 2 ) of each light tip were measured by a calibrated spectral device (PS-MARC [Patient Simulator-Managing Accurate Resin Curing] BlueLight Analytic Inc., Halifax, Nova Scotia, Canada). For each group, 5 new curing tips were involved and a total of 25 cycles were performed. For the autoclave group, each of the 5 curing tips was sterilized with an autoclave cycle (15 min). In the second group, the 5 tested tips were wiped with a disinfectant solution (MinutenSpray, APMD GmbH, Munich, Germany) and then covered with a clear commercial disposable barrier (Disposa-Shield, Dentsply, USA). The statistical analysis involved using the t -test and the Tukey test. Results Analysis of the data showed reductions of Irradiance Values in both groups compared with the baseline Values. The group with autoclaved curing tips had a lower Value compared with the disinfectant/barrier tips group. There were statistically significant differences between the tested groups ( P Conclusion The quality of the tested LCU was reduced when either of the above infection control techniques was used. Clinicians are recommended to monitor their LCU by applying the same infection control methods on light tips when testing its Irradiance Value.
Greg Kopp - One of the best experts on this subject based on the ideXlab platform.
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a new lower Value of total solar Irradiance evidence and climate significance
Geophysical Research Letters, 2011Co-Authors: Greg Kopp, J L LeanAbstract:[1] The most accurate Value of total solar Irradiance during the 2008 solar minimum period is 1360.8 ± 0.5 W m−2 according to measurements from the Total Irradiance Monitor (TIM) on NASA's Solar Radiation and Climate Experiment (SORCE) and a series of new radiometric laboratory tests. This Value is significantly lower than the canonical Value of 1365.4 ± 1.3 W m−2 established in the 1990s, which energy balance calculations and climate models currently use. Scattered light is a primary cause of the higher Irradiance Values measured by the earlier generation of solar radiometers in which the precision aperture defining the measured solar beam is located behind a larger, view-limiting aperture. In the TIM, the opposite order of these apertures precludes this spurious signal by limiting the light entering the instrument. We assess the accuracy and stability of Irradiance measurements made since 1978 and the implications of instrument uncertainties and instabilities for climate research in comparison with the new TIM data. TIM's lower solar Irradiance Value is not a change in the Sun's output, whose variations it detects with stability comparable or superior to prior measurements; instead, its significance is in advancing the capability of monitoring solar Irradiance variations on climate-relevant time scales and in improving estimates of Earth energy balance, which the Sun initiates.
Manuel Simões - One of the best experts on this subject based on the ideXlab platform.
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Effect of light supply on CO 2 capture from atmosphere by Chlorella vulgaris and Pseudokirchneriella subcapitata
Mitigation and Adaptation Strategies for Global Change, 2013Co-Authors: Jcm Pires, Ana L. Gonçalves, Fernando G. Martins, Maria C. M. Alvim-ferraz, Manuel SimõesAbstract:Carbon dioxide (CO 2 ) is one of the primary greenhouse gases that contribute to climate change. Consequently, emission reduction technologies will be needed to reduce CO 2 atmospheric concentration. Microalgae may have an important role in this context. They are photosynthetic microorganisms that are able to fix atmospheric CO 2 using solar energy with efficiency ten times higher than terrestrial plants. The objectives of this study were: (i) to analyse the effect of light supply on the growth of Chlorella vulgaris and Pseudokirchneriella subcapitata; (ii) to assess the atmospheric CO 2 capture by these microalgae; and (iii) to determine the parameters of the Monod model that describe the influence of Irradiance on the growth of the selected microalgae. Both microalgae presented higher growth rates with high Irradiance Values and discontinuous light supply. The continuous supply of light at the highest Irradiance Value was not beneficial for C. vulgaris due to photooxidation. Additionally, C. vulgaris achieved the highest CO 2 fixation rate with the Value of 0.305 g-CO 2 L −1 d −1 . The parameters of the Monod model demonstrated that C. vulgaris can achieve higher specific growth rates (and higher CO 2 fixation rates) if cultivated under higher Irradiances than the studied Values. The presented results showed that microalgal culture is a promising strategy for CO 2 capture from atmosphere. Copyright Springer Science+Business Media Dordrecht 2014
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Lipid production of Chlorella vulgaris and Pseudokirchneriella subcapitata
international journal of energy and environmental engineering, 2013Co-Authors: Ana L. Gonçalves, José Cm Pires, Manuel SimõesAbstract:Background: The depletion of fossil fuel reserves has stimulated the search for sustainable sources of energy that are carbon-neutral or renewable. In this context, microalgae are a promising energetic resource. They are photosynthetic microorganisms that use CO2 as carbon source, with high specific growth rates. Furthermore, some species present high lipid content that can be easily converted into biodiesel. Accordingly, this study aims to analyze the effect of light supply (one of the most important culture parameters) on lipid production of selected microalgae, Chlorella vulgaris and Pseudokirchneriella subcapitata. Methods: Both microalgal species were cultured under different light Irradiance Values (36, 72, 96, and 126 μ Em �2 s �1 ) and for each light Irradiance Value, three light/dark ratios (10:14, 14:10, and 24:0) were tested. Lipid contents of both microalgae were then determined using a recently developed colorimetric method.
Richard B. Price - One of the best experts on this subject based on the ideXlab platform.
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Ability of four dental radiometers to measure the light output from nine curing lights
Journal of Dentistry, 2016Co-Authors: Carlos Alberto Kenji Shimokawa, J. E. Harlow, Miriam Lacalle Turbino, Richard B. PriceAbstract:Abstract Objectives To evaluate the accuracy of four dental radiometers when measuring the output from nine light curing units (LCUs). Methods The light output from nine light-emitting diode LCUs was measured with a laboratory-grade power meter (PowerMax-Pro 150 HD) and four dental radiometers (Bluephase Meter II, SDI LED Radiometer, Kerr LED Radiometer, and LEDEX CM4000). Ten measurements were made of each LCU with each radiometer. Analysis of variance (ANOVA) followed by Tukey tests (α = 0.05) were used to determine if there was a difference between the calculated Irradiance Values from the power meter and those from the radiometers. Where applicable, the LCUs were ranked according to their power and Irradiance Values. The emission spectra from the LCUs was measured using an integrating sphere attached to a fiber-optic spectrometer (N = 10). The beam profile of the LCUs was measured with a beam profiler camera. Results Of the dental radiometers, only the Bluephase Meter II could measure power. ANOVA showed no significant difference between power Values measured with the laboratory-grade meter and the Bluephase Meter II (p = 0.527). The difference between the mean Irradiance reported by the various radiometers for the same LCU was up to 479 mW/cm 2 . The ranking of the power Values obtained using the laboratory-grade meter was the same for the Bluephase Meter II. Conclusion When compared to the calculated Irradiance Values from the laboratory-grade power meter, the Bluephase Meter II provided the most accurate data. Clinical significance Considering the great variation between the Irradiance Values provided by radiometers and their overall inaccuracy when compared to a laboratory-grade meter, dentists should not place too much faith in the absolute Irradiance Value. However, hand-held radiometers can be used to monitor changes in the light output of LCUs over time.
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Localised Irradiance distribution found in dental light curing units
Journal of Dentistry, 2013Co-Authors: Pierre Luc Michaud, Richard B. Price, Daniel Labrie, Frederick A. Rueggeberg, Braden SullivanAbstract:Abstract Objective To measure the localised Irradiance and wavelength distributions from dental light curing units (LCUs) and establish a method to characterise their output. Methods 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 1 mm2. 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. Results 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. Conclusions 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. Clinical significance 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 premature failure of the restoration.
