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

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.

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Kinetic energy and spatial distribution of ions in high irradiance laser ionization source

Journal of Analytical Atomic Spectrometry ◽

10.1039/c1ja00002k ◽

2011 ◽

Vol 26 (6) ◽

pp. 1183 ◽

Cited By ~ 6

Author(s):

Yiming Lin ◽

Ruibin Xu ◽

Lingfeng Li ◽

Wei Hang ◽

Jian He ◽

...

Keyword(s):

Spatial Distribution ◽

Kinetic Energy ◽

High Irradiance ◽

Laser Ionization ◽

Ionization Source

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High-Irradiance Degradation Studies of Metamorphic 1eV GaInAs Solar Cells

MRS Proceedings ◽

10.1557/opl.2012.1028 ◽

2012 ◽

Vol 1432 ◽

Cited By ~ 2

Author(s):

Ryan M. France ◽

Myles A. Steiner

Keyword(s):

Solar Cells ◽

Active Region ◽

Dislocation Density ◽

Dark Current ◽

Degradation Mechanism ◽

Control Cell ◽

High Irradiance ◽

Threading Dislocation ◽

Threading Dislocation Density ◽

Degradation Studies

ABSTRACTInitial tests are performed regarding the degradation of lattice-mismatched GaInAs solar cells. 1eV metamorphic GaInAs solar cells with 1-2×106 cm-2 threading dislocation density in the active region are irradiated with an 808 nm laser for 2 weeks time under a variety of temperature and illumination conditions. All devices show a small degradation in Voc that is logarithmic with time. The absolute loss in performance after 2 weeks illuminated at 1300 suns equivalent and 125°C is 7 mV Voc and 0.2% efficiency, showing these devices to be relatively stable. The dark current increases with time and is analyzed with a two-diode model. A GaAs control cell degrades at the same rate, suggesting that the observed degradation mechanism is not related to the additional dislocations in the GaInAs devices.

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Recent Progress in the Study of Peroxiredoxin in the Harmful Algal Bloom Species Chattonella marina

Antioxidants ◽

10.3390/antiox10020162 ◽

2021 ◽

Vol 10 (2) ◽

pp. 162

Author(s):

Yohei Shimasaki ◽

Koki Mukai ◽

Yuki Takai ◽

Xuchun Qiu ◽

Yuji Oshima

Keyword(s):

Oxidative Stress ◽

Growth Phase ◽

Critical Role ◽

High Irradiance ◽

Growth Potential ◽

Exponential Growth Phase ◽

Wild Type ◽

Chattonella Marina ◽

Strong Light ◽

Expression Strain

Peroxiredoxin (Prx) is a relatively recently discovered antioxidant enzyme family that scavenges peroxides and is known to be present in organisms from biological taxa ranging from bacteria to multicellular eukaryotes, including photosynthetic organisms. Although there have been many studies of the Prx family in higher plants, green algae, and cyanobacteria, few studies have concerned raphidophytes and dinoflagellates, which are among the eukaryotic algae that cause harmful algal blooms (HABs). In our proteomic study using 2-D electrophoresis, we found a highly expressed 2-Cys peroxiredoxin (2-CysPrx) in the raphidophyte Chattonella marina var. antiqua, a species that induces mass mortality of aquacultured fish. The abundance of the C. marina 2-CysPrx enzyme was highest in the exponential growth phase, during which photosynthetic activity was high, and it then decreased by about a factor of two during the late stationary growth phase. This pattern suggested that 2-CysPrx is a key enzyme involved in the maintenance of high photosynthesis activity. In addition, the fact that the depression of photosynthesis by excessively high irradiance was more severe in the 2-CysPrx low-expression strain (wild type) than in the normal-expression strain (wild type) of C. marina suggested that 2-CysPrx played a critical role in protecting the cell from oxidative stress caused by exposure to excessively high irradiance. In the field of HAB research, estimates of growth potential have been desired to predict the population dynamics of HABs for mitigating damage to fisheries. Therefore, omics approaches have recently begun to be applied to elucidate the physiology of the growth of HAB species. In this review, we describe the progress we have made using a molecular physiological approach to identify the roles of 2-CysPrx and other antioxidant enzymes in mitigating environmental stress associated with strong light and high temperatures and resultant oxidative stress. We also describe results of a survey of expressed Prx genes and their growth-phase-dependent behavior in C. marina using RNA-seq analysis. Finally, we speculate about the function of these genes and the ecological significance of 2-CysPrx, such as its involvement in circadian rhythms and the toxicity of C. marina to fish.

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On some automorphic properties of Galois traces of class invariants from generalized Weber functions of level 5

Open Mathematics ◽

10.1515/math-2019-0115 ◽

2019 ◽

Vol 17 (1) ◽

pp. 1631-1651

Author(s):

Ick Sun Eum ◽

Ho Yun Jung

Keyword(s):

Modular Forms ◽

Fourier Coefficients ◽

Singular Values ◽

Congruence Subgroups ◽

Maass Form ◽

Weakly Holomorphic Modular Forms ◽

Reciprocity Law ◽

Class Invariants ◽

Higher Genus ◽

Holomorphic Modular Forms

Abstract After the significant work of Zagier on the traces of singular moduli, Jeon, Kang and Kim showed that the Galois traces of real-valued class invariants given in terms of the singular values of the classical Weber functions can be identified with the Fourier coefficients of weakly holomorphic modular forms of weight 3/2 on the congruence subgroups of higher genus by using the Bruinier-Funke modular traces. Extending their work, we construct real-valued class invariants by using the singular values of the generalized Weber functions of level 5 and prove that their Galois traces are Fourier coefficients of a harmonic weak Maass form of weight 3/2 by using Shimura’s reciprocity law.

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Analysis of the holographic reciprocity law for dichromated gelatin

Applied Optics ◽

10.1364/ao.31.003200 ◽

1992 ◽

Vol 31 (17) ◽

pp. 3200 ◽

Cited By ~ 1

Author(s):

I. Pascual ◽

A. Beléndez ◽

A. Fimia

Keyword(s):

Reciprocity Law ◽

Dichromated Gelatin

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Interactive effects of nitrogen and irradiance on growth and partitioning of dry mass and nitrogen in young tomato plants

Functional Plant Biology ◽

10.1071/fp02087 ◽

2002 ◽

Vol 29 (11) ◽

pp. 1319 ◽

Cited By ~ 31

Author(s):

Corine C. de Groot ◽

Leo F. M. Marcelis ◽

Riki van den Boogaard ◽

Hans Lambers

Keyword(s):

Leaf Area ◽

Dry Mass ◽

High Irradiance ◽

Interactive Effects ◽

Tomato Plants ◽

N Limitation ◽

N Supply ◽

N Concentration ◽

Growth Irradiance ◽

Dry Mass Partitioning

The interactive effects of irradiance and N on growth of young tomato plants (Lycopersicon esculentum Mill.) were studied. Plants were grown at 70 or 300 μmol photons m–2 s–1, hereafter referred to as 'low' and 'high' irradiance, and at a range of exponential N supply rates (70–370 mg g–1 d–1) or at a constant concentration in the nutrient solution of 12 mM NO3–. At both irradiance levels, leaf area ratio was more important than net assimilation rate (NAR) in explaining effects of N on growth at mild N limitation. However, at severe N limitation, NAR became the most important parameter, as indicated by calculated growth response coefficients. Furthermore, this study shows that N supply and growth irradiance interacted strongly. The decrease of specific leaf area with increasing N limitation and increasing growth irradiance correlated with increasing leaf dry mass percentage and starch concentration. Furthermore, at low irradiance, plants partitioned more dry mass to the stem. Dry mass partitioning to roots increased with decreasing plant N concentration, and this relation appeared to be independent of irradiance. Shading increased plant N concentration and decreased dry mass partitioning to roots. Also, the relationship between plant N concentration and N partitioning to different plant organs was largely independent of growth irradiance.

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