Study on the Thermal Stress Distribution of Crystalline Silicon Solar Cells in BIPV

AbstractThe working temperature of BIPV modules is high than ground-mounted PV. Based on the theory of material mechanics and thermal stress analysis, the stress distribution of metallization interconnects system for crystalline silicon solar module in BIPV was studied for the first time. The shear stress and normal stress distribution of soldered structure for crystalline silicon solar cell under the thermal field were discussed. And the results show the stress distribution is not simply linear relationship as some results found. But there is a stress concentration at the edge, which was considered as the true reason that caused V-notch at the edge of soldered solar cell. The conclusions we got in this paper provide a theoretical basis for reliability of c-Si BIPV modules

Large Ecosystem Service Benefits of Assisted Natural Regeneration

China manages the largest monoculture plantations in the world, with 24% being Chinese fir plantations. Maximizing the ecosystem services of Chinese fir plantations has important implications in global carbon cycle and biodiversity protection. Assisted natural regeneration (ANR) is a practice to convert degraded lands into more productive forests with great ecosystems services. However, the quantitative understanding of ANR ecosystem service benefits is very limited. We conducted a comprehensive field manipulation experiment to evaluate the ANR potentials. We quantified and compared key ecosystem services including surface runoff, sediment yield, dissolved organic carbon export, plant diversity, and aboveground carbon accumulation of ANR of secondary forests dominated by Castanopsis carlesii to that of Chinese fir and C. carlesii plantations. Our results showed that ANR of C. carlesii forest reduced surface runoff and sediment yield up to 50% compared with other young plantations in the first 3 years and substantially increased plant diversity. ANR also reduced the export of dissolved organic carbon by 60–90% in the first 2 years. Aboveground biomass of the young ANR forest was approximately 3–4 times of that of other young plantations, while aboveground biomass of mature ANR forests was approximately 1.4 times of that of mature Chinese fir plantations of the same age. If all Chinese fir plantations in China were replaced by ANR forests, potentially 0.7 Pg more carbon will be stored in aboveground in one rotation (25 years). The results indicate that ANR triggers positive feedbacks among soil and water conservation, biodiversity protection, and biomass accumulation and thereby enhances ecosystem services

Interface-engineered ferroelectricity of epitaxial Hf\u3csub\u3e0.5\u3c/sub\u3eZr\u3csub\u3e0.5\u3c/sub\u3eO\u3csub\u3e2\u3c/sub\u3e thin films

Ferroelectric hafnia-based thin films have attracted intense attention due to their compatibility with complementary metal-oxide-semiconductor technology. However, the ferroelectric orthorhombic phase is thermodynamically metastable. Various efforts have been made to stabilize the ferroelectric orthorhombic phase of hafnia-based films such as controlling the growth kinetics and mechanical confinement. Here, we demonstrate a key interface engineering strategy to stabilize and enhance the ferroelectric orthorhombic phase of the Hf0.5Zr0.5O2 thin film by deliberately controlling the termination of the bottom La0.67Sr0.33MnO3 layer. We find that the Hf0.5Zr0.5O2 films on the MnO2-terminated La0.67Sr0.33MnO3 have more ferroelectric orthorhombic phase than those on the LaSrO-terminated La0.67Sr0.33MnO3, while with no wake-up effect. Even though the Hf0.5Zr0.5O2 thickness is as thin as 1.5nm, the clear ferroelectric orthorhombic (111) orientation is observed on the MnO2 termination. Our transmission electron microscopy characterization and theoretical modelling reveal that reconstruction at the Hf0.5Zr0.5O2/ La0.67Sr0.33MnO3 interface and hole doping of the Hf0.5Zr0.5O2 layer resulting from theMnO2 interface termination are responsible for the stabilization of the metastable ferroelectric phase of Hf0.5Zr0.5O2. We anticipate that these results will inspire further studies of interface-engineered hafnia-based systems

The Mechanism of Antifungal Action of Essential Oil from Dill (Anethum graveolens L.) on Aspergillus flavus

The essential oil extracted from the seeds of dill (Anethum graveolens L.) was demonstrated in this study as a potential source of an eco-friendly antifungal agent. To elucidate the mechanism of the antifungal action further, the effect of the essential oil on the plasma membrane and mitochondria of Aspergillus flavus was investigated. The lesion in the plasma membrane was detected through flow cytometry and further verified through the inhibition of ergosterol synthesis. The essential oil caused morphological changes in the cells of A. flavus and a reduction in the ergosterol quantity. Moreover, mitochondrial membrane potential (MMP), acidification of external medium, and mitochondrial ATPase and dehydrogenase activities were detected. The reactive oxygen species (ROS) accumulation was also examined through fluorometric assay. Exposure to dill oil resulted in an elevation of MMP, and in the suppression of the glucose-induced decrease in external pH at 4 µl/ml. Decreased ATPase and dehydrogenase activities in A. flavus cells were also observed in a dose-dependent manner. The above dysfunctions of the mitochondria caused ROS accumulation in A. flavus. A reduction in cell viability was prevented through the addition of L-cysteine, which indicates that ROS is an important mediator of the antifungal action of dill oil. In summary, the antifungal activity of dill oil results from its ability to disrupt the permeability barrier of the plasma membrane and from the mitochondrial dysfunction-induced ROS accumulation in A. flavus

Effect of dodecyl dimethyl benzyl ammonium chloride on CH4 hydrate growth and agglomeration in oil-water systems

Low dosage hydrate inhibitor (LDHI) is an effective choice to prevent hydrate formation and blockage in petroleum and natural gas processing industry. This study investigated the effect of dodecyl dimethyl benzyl ammonium chloride (DDBAC) on CH4 hydrate growth and agglomeration in oil-water systems. Hydrate formation kinetics and torque changes were determined with the isothermal-isochoric method. The kinetic experimental results revealed that 0.35 wt% DDBAC exerted a strong and stable inhibition effect on CH4 hydrate growth, represented by long induction time and low gas uptake amount. The chemical affinity modeling calculation results showed that DDBAC decreased normalized hydrate formation rate and increased the kinetic equilibrium time. The torque changes demonstrated that anti agglomeration effect strengthened with the increase of DDBAC mass fraction. In addition, the mechanism of CH4 hydrate formation in studied system was proposed combining the experimental results, hydrate morphology and DDBAC's properties. It showed that DDBAC could hinder gas dissolution in oil phase, separate hydrate particles from each other and make hydrate surface soft. These results are of fundamental value in developing LDHI and understanding the mechanism of hydrate formation, which are essential in preventing hydrate blockage and ensuring safety production of oil and gas. (c) 2020 Elsevier Ltd. All rights reserved

Stability Conditions for Semiclathrate Hydrates Formed with Tetrabutylammonium Chloride plus Tetrabutylphosphonium Chloride + CH4

Semiclathrate hydrate is a promising method to ease the thermodynamic conditions of gas hydrate formation for hydrate-based gas storage and transportation on the industrial scale. The phase equilibrium conditions of mixed semiclathrate hydrate formed with tetrabutylammonium chloride (TBAC) + tetrabutylphosphonium chloride (TBPC) + CH4 were measured systematically by employing the isochoric pressure-search method. The data revealed that mixed TBAC + TBPC exerted relatively higher stabilization effect on CH4 hydrate than pure TBAC or TBPC, and the strongest stabilization effect showed up in system with 0.0300 total salt mole fraction (x(salt)) and 0.75 TBAC salt ratio (x(TBAC)/x(salt)). In addition, the dissociation enthalpies of mixed (TBAC + TBPC + CH4) hydrate were calculated with the obtained experimental data by using the simplified Clausius-Clapeyron equation and the Peng-Robinson equation of state. It was found that the mean dissociation enthalpies for mixed (TBAC + TBPC + CH4) hydrate with different salt concentration relied on a (153.04 to 203.92 kJ/molCH(4)) scale, which was significantly higher than that of the pure CH4 hydrate. The data generated in this work showed that mixed TBAC + TBPC could enhance CH4 hydrate stability and the stored energy effectively

Investigation on Potential-Induced Degradation in a 50 MWp Crystalline Silicon Photovoltaic Power Plant

The regular performance deterioration of P-type crystalline silicon solar modules and module strings caused by potential-induced degradation in a photovoltaic power plant was found in the field. The PID-affected solar modules dismounted from the photovoltaic power plant were further investigated systematically in the laboratory. For the first time, we found that the neutral point of voltage in a module string moved forward to the positive pole for a PID-affected module string as time goes on. Even if low positive voltage is applied to a PID-prone module, it could cause PID. The thermographic and electroluminescence (EL) images of a PID-affected module string also exhibit a regular degradation pattern. This is in good agreement with the measured power loss of the dismounted solar modules under standard test conditions. The results obtained in this paper show that the maximum power degradation rate of solar modules was as high as 53.26% after only one year of operation because of PID in the field. Due to the vast amount of solar modules and incomplete recovery, this is a terrible catastrophe for the owner of a power plant and module producer