Applicability of Exposure Reciprocity Law for Fast Polymerization of Restorative Composites Containing Various Photoinitiating Systems

2021 ◽  
Author(s):  
A Tichy ◽  
P Bradna
Keyword(s):  
High Power ◽  
Irradiation Time ◽  
Spectral Characteristics ◽  
Degree Of Polymerization ◽  
High Irradiance ◽  
Bottom Surface ◽  
Surface Microhardness ◽  
Radiant Exposure ◽  
Reciprocity Law ◽  
Restorative Composites

SUMMARY Objectives: The exposure reciprocity law (ERL) has been used to calculate the optimal irradiation time of dental composites. This study examined the applicability of ERL for fast polymerization of restorative composites containing various photoinitiating systems using a high-power multi-peak light-emitting diode (LED) lamp. Methods: Three commercial composites differing in photoinitiating systems were tested: Filtek Ultimate Universal Restorative (FU) with a camphorquinone-amine (CQ-A) photoinitiating system, Tetric EvoCeram (TEC) with CQ-A and (2,4,6-trimethylbenzoyl)phosphine oxide (TPO), and Estelite Σ Quick (ESQ) with CQ and a radical amplified photopolymerization (RAP) initiator. Specimens 2-mm thick were polymerized using a high-power multipeak LED lamp (Valo) at 3 pairs of radiant exposures (referred to as low, moderate, and high) ranging from 15.8–26.7 J/cm2. They were achieved by different combinations of irradiation time (5–20 seconds) and irradiance (1300–2980 mW/cm2) as determined with a calibrated spectrometer. Knoop microhardness was measured 1, 24, and 168 hours after polymerization on specimen top (irradiated) and bottom surfaces to characterize the degree of polymerization. The results were statistically analyzed using a three-way analysis of variance and Tukey’s post hoc tests, α = 0.05. Results: Microhardness increased with radiant exposure and except for ESQ, top-surface microhardness was significantly higher than that on bottom surfaces. Combinations of high irradiance and short irradiation time significantly increased the top-surface microhardness of TEC at low and moderate radiant exposures, and the bottom-surface microhardness of FU at a low radiant exposure. In contrast, the microhardness of ESQ on both surfaces at high radiant exposure increased significantly when low irradiance and long irradiation time were used. With all tested composites, bottom-surface microhardness obtained at low radiant exposure was below 80% of the maximum top-surface microhardness, indicating insufficient polymerization. Conclusion: Combinations of irradiance and irradiation time had a significant effect on microhardness, which was affected by photoinitiators and the optical properties of composites as well as spectral characteristics of the polymerization lamp. Therefore, ERL cannot be universally applied for the calculation of optimal composite irradiation time. Despite high irradiance, fast polymerization led to insufficient bottom-surface microhardness, suggesting the necessity to also characterize the degree of polymerization on the bottom surfaces of composite increments when assessing the validity of ERL.

Spectral Characteristics of Narrow-Linewidth High-Power 1180 nm DBR Laser With Surface Gratings

2017 ◽  
Vol 29 (1) ◽  
pp. 114-117 ◽  
Author(s):  
Heikki Virtanen ◽  
Antti T. Aho ◽  
Jukka Viheriala ◽  
Ville-Markus Korpijarvi ◽  
Topi Uusitalo ◽  
...  
Keyword(s):  
High Power ◽  
Spectral Characteristics ◽  
Narrow Linewidth

Weld width prediction of weldment bottom surface in high-power disk laser welding

2017 ◽  
Vol 25 (9) ◽  
pp. 2524-2531
Author(s):  
陈子琴 CHEN Zi-qin ◽  
高向东 GAO Xiang-dong ◽  
王 琳 WANG Lin
Keyword(s):  
Laser Welding ◽  
High Power ◽  
Bottom Surface ◽  
Disk Laser ◽  
Weld Width

Heterodyne meter of spectral characteristics of high-power nanosecond X-band microwave pulses

2000 ◽  
Vol 43 (1) ◽  
pp. 88-90 ◽  
Author(s):  
A. A. El’chaninov ◽  
A. I. Klimov ◽  
K. I. Kurkan
Keyword(s):  
High Power ◽  
Spectral Characteristics ◽  
X Band ◽  
Microwave Pulses

scholarly journals Perspective Ground-based Method for Diagnostics of the Lower Ionosphere and the Neutral Atmosphere

2013 ◽  
Vol 22 (1) ◽  
Author(s):  
N. V. Bakhmetieva ◽  
G. I. Grigoriev ◽  
A. V. Tolmacheva
Keyword(s):  
Radio Wave ◽  
High Power ◽  
Relative Concentration ◽  
Spectral Characteristics ◽  
Lower Ionosphere ◽  
Internal Gravity Waves ◽  
Spatial Period ◽  
Neutral Atmosphere ◽  
Radio Waves ◽  
D Region

AbstractWe present a new perspective ground-based method for diagnostics of the ionosphere and atmosphere parameters. The method uses one of the numerous physical phenomena observed in the ionosphere illuminated by high-power radio waves. It is a generation of the artificial periodic irregularities (APIs) in the ionospheric plasma. The APIs were found while studying the effects of ionospheric high-power HF modification. It was established that the APIs are formed by a standing wave that occurs due to interference between the upwardly radiated radio wave and its reflection off the ionosphere. The API studies are based upon observation of the Bragg backscatter of the pulsed probe radio wave from the artificial periodic structure. Bragg backscatter occurs if the spatial period of the irregularities is equal to half a wavelength of the probe signal. The API techniques makes it possible to obtain the following information: the profiles of electron density from the lower D-region up to the maximum of the F-layer; the irregular structure of the ionosphere including split of the regular E-layer, the sporadic layers; the vertical velocities in the D- and E-regions of the ionosphere; the turbulent velocities, turbulent diffusion coefficients and the turbopause altitude; the neutral temperatures and densities at the E-region altitudes; the parameters of the internal gravity waves and their spectral characteristics; the relative concentration of negative oxygen ions in the D-region. Some new results obtained by the API technique are discussed.

Thermal-Enhanced and Cost-Effective 3D IC Integration With TSV (Through-Silicon Via) Interposers for High-Performance Applications

2010 ◽  
Author(s):  
John H. Lau ◽  
Y. S. Chan ◽  
S. W. Ricky Lee
Keyword(s):  
Low Power ◽  
High Power ◽  
Heat Sink ◽  
High Performance ◽  
Low Cost ◽  
Bottom Surface ◽  
Heat Spreader ◽  
Creep Theory ◽  
Integration System ◽  
3D Ic

A low-cost (with bare chips) and high (electrical, thermal, and mechanical) performance 3D IC integration system-in-package (SiP) is designed and described. This system consists of a silicon interposer with through-silicon vias (TSV) [1–24] and redistribution layers (RDL), which carries the high-power flip chips with microbumps on its top surface and the low-power chips at its bottom surface. TSVs in the high- and low-power chips are optional but should be avoided. The backside of the high-power chips is attached to a heat spreader with or w/o a heat sink. This 3D IC integration system is supported (packaged) by a simple conventional organic substrate. The heat spreader (with or w/o heat sink) and the substrate are connected by a ring stiffener, which provides adequate standoff for the 3D IC integration system. This novel structural design offers potential solutions for high-power, high-performance, high pin-count, ultra fine-pitch, small real-estate, and low-cost applications. Thermal management and reliability of the proposed systems are demonstrated by simulations based on heat-transfer theory and time and temperature dependent creep theory.

scholarly journals Apparent violation of the radiant exposure reciprocity law in interline CCDs

2006 ◽  
Vol 45 (17) ◽  
pp. 3991 ◽  
Author(s):  
Alejandro Ferrero ◽  
Joaquin Campos ◽  
Alicia Pons
Keyword(s):  
Radiant Exposure ◽  
Reciprocity Law ◽  
Apparent Violation

scholarly journals Structural Evolution of Burmese Amber during Petrifaction Based on a Comparison of the Spectral Characteristics of Amber, Copal, and Rosin

2019 ◽  
Vol 2019 ◽  
pp. 1-11
Author(s):  
Feng Bai ◽  
Huifang Liang ◽  
Hongting Qu
Keyword(s):  
Structural Changes ◽  
Spectral Characteristics ◽  
Structural Evolution ◽  
Degree Of Polymerization ◽  
Organic Polymer ◽  
Polymer Mixture ◽  
Burmese Amber ◽  
Solubility Study ◽  
Visible Spectra ◽  
Peak Areas

This paper presents a spectroscopic analysis and solubility study of rosin, copal, and Burmese amber samples to reveal the structural changes that occur during amber formation. The infrared spectra indicate that during the long geological process of amber formation, small resin molecules first crosslinked and slowly oxidized, eventually forming a stable organic polymer mixture. An analysis of Raman peak areas demonstrated that among the tested samples, the degree of polymerization is highest in Burmese amber and lowest in rosin. Ultraviolet-visible spectra indicate the presence of unsaturated bonds (e.g., carbonyl groups) or conjugated systems in Burmese amber, copal, and rosin. The evaluation of amber, rosin, and copal solubility in six solvents (ethanol, acetone, 1,4-dioxane, ethylacetate, N,N-dimethylamide, and dichloromethane) demonstrated that solubility decreases in the following order: rosin > copal > Burmese amber. Together, the results suggest that the structure of Burmese amber includes large organic molecules containing six-membered rings along with CH2, CH3, C=O, C=C, C–O, and C–C groups.

Spatio-spectral characteristics of a high power, high brightness CW InGaAs/AlGaAs unstable resonator semiconductor laser

1993 ◽  
Vol 29 (18) ◽  
pp. 1597 ◽  
Author(s):  
Z. Bao ◽  
R.K. DeFreez ◽  
P.D. Carleson ◽  
C. Largent ◽  
C. Moeller ◽  
...  
Keyword(s):  
Semiconductor Laser ◽  
High Power ◽  
Spectral Characteristics ◽  
Unstable Resonator ◽  
High Brightness

High irradiance curing and anomalies of exposure reciprocity law in resin-based materials

2011 ◽  
Vol 39 (8) ◽  
pp. 549-557 ◽  
Author(s):  
M. Hadis ◽  
J.G. Leprince ◽  
A.C. Shortall ◽  
J. Devaux ◽  
G. Leloup ◽  
...  
Keyword(s):  
High Irradiance ◽  
Reciprocity Law

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

2017 ◽  
Vol 42 (5) ◽  
pp. 537-547 ◽  
Author(s):  
CAK Shimokawa ◽  
B Sullivan ◽  
ML Turbino ◽  
CJ Soares ◽  
RB Price
Keyword(s):  
Emission Spectrum ◽  
Broad Spectrum ◽  
Light Transmission ◽  
High Irradiance ◽  
Degree Of Conversion ◽  
Single Peak ◽  
Bottom Surface ◽  
Light Conditions ◽  
Violet Light ◽  
Light Curing

SUMMARY Purpose: 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/cm2 on the polymerization and light transmission of four resin-based composites (RBCs). Methods and Materials: 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/cm2) or high irradiance (3600 mW/cm2) 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. Results: 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 (p<0.05). The RBCs that included alternative photoinitiators had greater microhardness values at the top when cured with broad-spectrum lights, while at the bottom, where little violet light was observed, the results were equal or higher when they were photoactivated with single-peak blue lights. With the exception of the microhardness at the top of TPH, equivalent or higher microhardness and degree-of-conversion values were achieved at the bottom surface when the standard (1200 mW/cm2) irradiance levels were used compared to when high irradiance levels were used. Conclusions: Considering the different behaviors of the tested RBCs, the emission spectrum and irradiance level influenced the polymerization of some RBCs. The RBCs that included alternative photoinitiators produced greater values at the top when cured with broad-spectrum lights, while at the bottom, results were equal or higher for the RBCs photoactivated with single-peak blue lights.

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