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Red/blue light ratio strongly affects steady-state photosynthesis, but hardly affects photosynthetic induction, in tomato ( <i>Solanum lycopersicum</i> )
摘要： Plants are often subjected to rapidly alternating light intensity and quality. While both short- and long-term changes in red and blue light affect leaf photosynthesis, their impact on dynamic photosynthesis is not well documented. It was tested how dynamic and steady-state photosynthetic traits were affected by red/blue ratios, either during growth or during measurements, in tomato leaves. Four red/blue ratios were used: monochromatic red (R100), monochromatic blue (B100), a red/blue light ratio of 9:1 (R90B10) and a red/blue light ratio of 7:3 (R70B30). R100 grown leaves showed decreased photosynthetic capacity (maximum rates of light-saturated photosynthesis, carboxylation, electron transport and triose phosphate use), leaf thickness and nitrogen concentrations. Acclimation to various red/blue ratios had limited effects on photosynthetic induction in dark-adapted leaves. B100 grown leaves had a ~15% larger initial NPQ transient than the other treatments, which may be beneficial for photoprotection under fluctuating light. B100 grown leaves also showed faster stomatal closure when exposed to low light intensity, which likely resulted from smaller stomata and higher stomatal density. When measured under different red/blue ratios, stomatal opening rate and photosynthetic induction rate were hardly accelerated by increased fractions of blue light in both growth chamber-grown leaves and greenhouse-grown leaves. However, steady-state photosynthesis rate 30 min after photosynthetic induction was strongly reduced in leaves exposed to B100 during the measurement. We conclude that varying red/blue light ratios during growth and measurement strongly affects steady-state photosynthesis, but has limited effects on photosynthetic induction rate.
关键词： Solanum lycopersicum,red/blue light ratio,photosynthesis,photosynthetic induction,steady-state photosynthesis,tomato
更新于2025-09-10 09:29:36
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Design and performance study on a large-scale hybrid CPV/T system based on unsteady-state thermal model
摘要： A hybrid CPV/T unit designed in this work concentrates solar radiation by a compound parabolic concentrator (CPC) and converts solar energy into electrical and thermal energy by a PV/T module. The CPC eliminating multiple reflections of solar radiation is defined as the ‘EMR-CPC’ in our previous work, which improves photoelectric and thermal conversion efficiencies. Two similar CPV/T units were tested with two-axis tracking device and south-north single-axis tracking device respectively, and the average photoelectric conversion efficiencies were 13% and 12%. A large-scale south-north tracking hybrid CPV/T system with sunlight collecting area of 810 m2 was built to explore practical application of this CPV/T unit. The whole-day thermal efficiency and total thermal output of the large-scale hybrid CPV/T system were 55% and 1,730,039 kJ respectively on April 14, 2017. The steady-state and unsteady-state thermal models of the hybrid CPV/T system were established and the energy loss was analyzed. The calculated whole-day comprehensive thermal efficiencies of the unsteady-state thermal model and the steady-state thermal model were 55.3% and 55.0% respectively, which were close to the measurement 55.8%. However, the steady-state thermal model failed to accurately predict the whole-day thermal efficiency variation of the system. In comparison, the unsteady-state thermal model accurately predicts instantaneous thermal efficiency of the system varying with meteorological conditions and its total daily heat output.
关键词： South-north tracking,Large-scale CPV/T system,Steady-state thermal model,Unsteady-state thermal model
更新于2025-09-09 09:28:46
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Angular dependence of SiO2 etching in plasmas containing heptafluoropropyl methyl ether
摘要： SiO2 was etched in heptafluoropropyl methyl ether (HFE-347mcc3)/Ar and C4F8/Ar plasmas, separately, to evaluate the feasibility of the use of fluorinated ether plasmas as an alternative to perfluoro carbon plasmas. The etch rates of SiO2 in HFE-347mcc3/Ar plasma were higher than those in C4F8/Ar plasma because the O atoms in HFE-347mcc3 produced O radicals that reacted with fluorocarbons to produce volatile products, thus consuming more fluorocarbon films. In HFE-347mcc3/Ar plasmas, the changes in the normalized etch yield (NEY) with ion-incident angle followed nearly the same patterns at bias voltages higher than ?600 V, while the NEY at ?400 V was lower than those at other bias voltages. On the other hand, the NEYs of C4F8/Ar plasmas increased with bias voltage, indicating a strong dependence on the bias voltage. The characteristic changes in the NEY in HFE-347mcc3/Ar plasmas were correlated with the thickness and the fluorine-to-carbon ratio of the steady-state film formed on the surface of the substrate.
关键词： Steady-state fluorocarbon film,Etch rate,Angular dependence,Fluorinated ether plasma,Perfluoro carbon plasma
更新于2025-09-09 09:28:46
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Infrared Investigations of the Neutral-Ionic Phase Transition in TTF-CA and Its Dynamics
摘要： The neutral-ionic phase transition in TTF-CA was investigated by steady-state and time-resolved infrared spectroscopy. We describe the growth of high-quality single crystals and their characterization. Extended theoretical calculations were performed in order to obtain the band structure, the molecular vibrational modes and the optical spectra along all crystallographic axes. The theoretical results are compared to polarization-dependent infrared reflection experiments. The temperature-dependent optical conductivity is discussed in detail. We study the photo-induced phase transition in the vicinity of thermally-induced neutral-ionic transition. The observed temporal dynamics of the photo-induced states is attributed to the random-walk of neutral-ionic domain walls. We simulate the random-walk annihilation process of domain walls on a one-dimensional chain.
关键词： domain-wall motion,neutral-ionic phase transition,steady-state and transient infrared spectroscopy,TTF-CA,charge-transfer salts,characterization,random-walk simulations,light-induced phase transition,vibrational spectroscopy,crystal growth
更新于2025-09-09 09:28:46
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Experimental and theoretical investigations of free radical photopolymerization: Inhibition and termination reactions
摘要： In this work, the inhibition and termination reactions occurring throughout a free radical photopolymerization initiated by a type-I photoinitiator are studied by kinetic modeling. The role of the macroradicals as the main oxygen trapping agents during the inhibition time is identified, and the absence of primary radical consumption by oxygen can be related to a high initiation efficiency at early times. The ratio of the termination reactions reveals that bimolecular termination remains the principal pathway for the cessation of macromolecule growth, even at high polymer conversion. Moreover, the evolution of the termination ratio during the polymerization can be correlated to both the diffusional control of the polymerization reactions as the polymer network grows and the photoinitiator consumption. Finally, the effect of the incident light intensity and the initial photoinitiator concentration on the termination reactions is assessed, and the validity of the steady-state assumption applied to the macroradical concentration discussed.
关键词： Oxygen inhibition,Kinetic modeling,Radical photopolymerization,Steady-state assumption,Type-I photoinitiator,Termination reactions
更新于2025-09-09 09:28:46
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Dual-phase whole-heart imaging using image navigation in congenital heart disease
摘要： Background: Dual-phase 3-dimensional whole-heart acquisition allows simultaneous imaging during systole and diastole. Respiratory navigator gating and tracking of the diaphragm is used with limited accuracy. Prolonged scan time is common, and navigation often fails in patients with erratic breathing. Image-navigation (iNAV) tracks movement of the heart itself and is feasible in single phase whole heart imaging. To evaluate its diagnostic ability in congenital heart disease, we sought to apply iNAV to dual-phase sequencing. Methods: Healthy volunteers and patients with congenital heart disease underwent dual-phase imaging using the conventional diaphragmatic-navigation (dNAV) and iNAV. Acquisition time was recorded and image quality assessed. Sharpness and length of the right coronary (RCA), left anterior descending (LAD), and circumflex (LCx) arteries were measured in both cardiac phases for both approaches. Qualitative and quantitative analyses were performed in a blinded and randomized fashion. Results: In volunteers, there was no significant difference in vessel sharpness between approaches (p > 0.05). In patients, analysis showed equal vessel sharpness for LAD and RCA (p > 0.05). LCx sharpness was greater with dNAV (p < 0.05). Visualized length with iNAV was 0.5 ± 0.4 cm greater than that with dNAV for LCx in diastole (p < 0.05), 1.0 ± 0.3 cm greater than dNAV for LAD in diastole (p < 0.05), and 0.8 ± 0.7 cm greater than dNAV for RCA in systole (p < 0.05). Qualitative scores were similar between modalities (p = 0.71). Mean iNAV scan time was 5:18 ± 2:12 min shorter than mean dNAV scan time in volunteers (p = 0.0001) and 3:16 ± 1:12 min shorter in patients (p = 0.0001). Conclusions: Image quality of iNAV and dNAV was similar with better distal vessel visualization with iNAV. iNAV acquisition time was significantly shorter. Complete cardiac diagnosis was achieved. Shortened acquisition time will improve clinical applicability and patient comfort.
关键词： Respiratory motion correction,Dual phase imaging,Congenital heart disease,Steady-state free precession MRI
更新于2025-09-04 15:30:14
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A New Dynamic Model to Predict Transient and Steady State PV Temperatures Taking into Account the Environmental Conditions
摘要： Photovoltaic (PV) cell and module temperature pro?les, Tc and Tpv, respectively, developed under solar irradiance were predicted and measured both at transient and steady state conditions. The predicted and measured Tc or Tpv covered both a bare c-Si PV cell, by SOLARTEC, at laboratory conditions using a solar light simulator, as well as various c-Si and pc-Si modules (SM55, Bioenergy 195W, Energy Solutions 125W) operating in ?eld conditions. The time constants, τ, of the Tc and Tpv pro?les were determined by the proposed model and calculated using the experimentally obtained pro?les for both the bare PV cell and PV modules. For model validation, the predicted steady state and transient temperature pro?les were compared with experimental ones and also with those generated from other models. The effect of the ambient temperature, Ta, wind speed, vw, and the solar irradiance, IT, on the model performance, as well as of the mounting geometries, was investigated and incorporated in the prediction model. The predicted temperatures had the best matching to the measured ones in comparison to those from six other models. The model developed is applicable to any geographical site and environmental conditions.
关键词： environmental effects,transient pro?les,steady state,time constant,PV cell temperature,wind velocity
更新于2025-09-04 15:30:14