Articles de revues : « Light harvesting methods »

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Chen, Ming, Kenneth P. Ghiggino, Albert W. H. Mau, Ezio Rizzardo, San H. Thang et Gerard J. Wilson. « Synthesis of light harvesting polymers by RAFT methods ». Chemical Communications, n^o 19 (11 septembre 2002) : 2276–77. http://dx.doi.org/10.1039/b206166j.

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Parveen, Farhana, Basavaraja Sannakki, Mohanrao V. Mandke et Habib M. Pathan. « Copper nanoparticles : Synthesis methods and its light harvesting performance ». Solar Energy Materials and Solar Cells 144 (janvier 2016) : 371–82. http://dx.doi.org/10.1016/j.solmat.2015.08.033.

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Park, Nam-Gyu. « Methods to Improve Light Harvesting Efficiency in Dye-Sensitized Solar Cells ». Journal of Electrochemical Science and Technology 1, n^o 2 (30 décembre 2010) : 69–74. http://dx.doi.org/10.5229/jecst.2010.1.2.069.

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Wang, S., et G. C. Bazan. « Optically Amplified RNA–Protein Detection Methods Using Light-Harvesting Conjugated Polymers ». Advanced Materials 15, n^o 17 (3 septembre 2003) : 1425–28. http://dx.doi.org/10.1002/adma.200305099.

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Jurinovich, Sandro, Lucas Viani, Carles Curutchet et Benedetta Mennucci. « Limits and potentials of quantum chemical methods in modelling photosynthetic antennae ». Physical Chemistry Chemical Physics 17, n^o 46 (2015) : 30783–92. http://dx.doi.org/10.1039/c5cp00986c.

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A critical overview of quantum chemical approaches to simulate the light-harvesting process in photosynthetic antennae is presented together with a perspective on the developments that need to be introduced to reach a quantitative predictive power.

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Kluender, Richard A., et Bryce J. Stokes. « Productivity and Costs of Three Harvesting Methods ». Southern Journal of Applied Forestry 18, n^o 4 (1 novembre 1994) : 168–74. http://dx.doi.org/10.1093/sjaf/18.4.168.

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Abstract Three stands were harvested by either clearcut, shelterwood, or single-tree selection methods. The single-tree selection method consisted of a light thinning in an even-aged stand as the initial basal area reduction cut required to convert the stand to uneven-aged structure. The contractor used two skidders (one grapple, one choker) and production chain saws to harvest all three tracts. Harvested sites were all similar in slope (10-15%), average dbh (12-14 in.), and preharvest number of stems by dbh. In the felling study, fell, walk, and limb-top time were all greater for the single-tree selection method. Time to process a tree was lowest for the clearcut, intermediate for shelterwood, and highest for single-tree selection method. For skidding, bunch building time was highest for the single-tree selection and lowest for the clearcut method. Average volume per cycle was consistently higher for the grapple skidder than the choker skidder; volume per cycle was lowest for the single-tree selection and highest for the clearcut method for both skidders. Time per cycle was consistently lower for the grapple skidder than the cable skidder. Time per cycle was lowest for the clearcut and highest for the single-tree selection method. Factors that affected felling productivity (in decreasing order) were: dbh of harvested stems, intertree distance, and method of harvest. Factors that affected skidding productivity (in decreasing order) were: skidder type, pull distance, average volume per cycle, and the method of harvest. Costs of felling and skidding were highest on the single-selection stand and lowest on the clearcut stand. Total percentage of stand area trafficked was lowest for the single tree stand. However, the total area disturbed to meet a wood procurement budget was lowest for the clearcut and highest for the single-tree method. South. J. Appl. For. 18(4): 168-174.

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Mustardy, Laszlo, Francis X. Cunningham et Elisabeth Gantt. « Localization and Quantitation of Chloroplast Enzymes and Light-Harvesting Components Using Immunocytochemical Methods ». Plant Physiology 94, n^o 1 (1 septembre 1990) : 334–40. http://dx.doi.org/10.1104/pp.94.1.334.

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Zhou, Dekai, Rencheng Zhuang, Xiaocong Chang et Longqiu Li. « Enhanced Light-Harvesting Efficiency and Adaptation : A Review on Visible-Light-Driven Micro/Nanomotors ». Research 2020 (25 août 2020) : 1–25. http://dx.doi.org/10.34133/2020/6821595.

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As visible light accounts for a larger proportion of solar energy and is harmless to living organisms, it has the potential to be the energy source of micro/nanomotors, which transform visible-light energy into mechanical motion, for different applications, especially in environmental remediation. However, how to precisely control the motion of visible-light-driven micro/nanomotors (VLD-MNMs) and efficiently utilize the weak visible-light photon energy to acquire rapid motion are significant challenges. This review summarizes the most critical aspects, involving photoactive materials, propulsion mechanisms, control methods, and applications of VLD-MNMs, and discusses strategies to systematically enhance the energy-harvesting efficiency and adaptation. At first, the photoactive materials have been divided into inorganic and organic photoactive materials and comprehensively discussed. Then, different propulsion mechanisms of the current VLD-MNMs are presented to explain the improvement in the actuation force, speed, and environmental adaptability. In addition, considering the characteristics of easy control of VLD-MNMs, we summarized the direction, speed, and cluster control methods of VLD-MNMs for different application requirements. Subsequently, the potential applications of VLD-MNMs, e.g., in environmental remediation, micropumps, cargo delivery, and sensing in microscale, are presented. Finally, discussions and suggestions for future directions to enhance the energy-harvesting efficiency and adaptation of VLD-MNMs are provided.

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Friedmans, Alan L., et Randall S. Alberte. « PHYLOGENETIC DISTRIBUTION OF THE MAJOR DIATOM LIGHT-HARVESTING PIGMENT-PROTEIN DETERMINED BY IMMUNOLOGICAL METHODS ». Journal of Phycology 23, n^o 3 (septembre 1987) : 427–33. http://dx.doi.org/10.1111/j.1529-8817.1987.tb02528.x.

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Wang, Xiaoqing, Gerhard Ritschel, Sebastian Wüster et Alexander Eisfeld. « Open quantum system parameters for light harvesting complexes from molecular dynamics ». Physical Chemistry Chemical Physics 17, n^o 38 (2015) : 25629–41. http://dx.doi.org/10.1039/c5cp03891j.

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Smyth, Cathal, Francesca Fassioli et Gregory D. Scholes. « Measures and implications of electronic coherence in photosynthetic light-harvesting ». Philosophical Transactions of the Royal Society A : Mathematical, Physical and Engineering Sciences 370, n^o 1972 (13 août 2012) : 3728–49. http://dx.doi.org/10.1098/rsta.2011.0420.

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We review various methods for measuring delocalization in light-harvesting complexes. Direct relations between inverse participation ratios (IPRs) and entanglement measures are derived. The B850 ring from the LH2 complex in Rhodopseudomonas acidophila is studied. By analysing electronic energy transfer dynamics in the B850 ring using different metrics for quantifying excitonic delocalization, we conclude that measures of entanglement are far more robust (in terms of time scale, temperature and level of decoherence) than IPRs, and are therefore more appropriate for the purpose of studying the time evolution of coherence in a system.

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Meutchieye, F., K. E. C. Tsafo et S. Niassy. « Inventory of edible insects and their harvesting methods in the Cameroon centre region ». Journal of Insects as Food and Feed 2, n^o 3 (15 juin 2016) : 145–52. http://dx.doi.org/10.3920/jiff2015.0082.

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This paper assesses the diversity and the exploitation of edible insects in the Cameroon centre region. To achieve this, 136 regular insects’ harvesters were randomly surveyed in all regional administrative divisions. Eighteen species, mainly caterpillars, are harvested as food. Harvesting and consumption of edible insects are happening throughout the year. The harvesters use 4 methods to collect the insects: (1) semi-domestication; (2) hand picking; (3) light trapping; and (4) net trapping. The harvesting predominantly is a household subsistence activity, although some edible insects are sold. Women and teenagers are the categories involved in edible insect collection. The study is preliminary and further identification of the insect species is needed. However, it constitutes a start for further research work which should focus on nutritional values, marketing chains analysis and pre domestication of identified important species.

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Coppola, Federico, Paola Cimino, Umberto Raucci, Maria Gabriella Chiariello, Alessio Petrone et Nadia Rega. « Exploring the Franck–Condon region of a photoexcited charge transfer complex in solution to interpret femtosecond stimulated Raman spectroscopy : excited state electronic structure methods to unveil non-radiative pathways ». Chemical Science 12, n^o 23 (2021) : 8058–72. http://dx.doi.org/10.1039/d1sc01238j.

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Ermilov, Eugeny A., Martin Schlak, Ronald Steffen, Xiao-Qiong Liu, Jian-Yong Liu et Beate Röder. « Energy transfer properties of a novel boron dipyrromethene–perylenediimide donor–acceptor dyad ». RSC Advances 5, n^o 82 (2015) : 67141–48. http://dx.doi.org/10.1039/c5ra10077a.

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Politi, Bastien, Alain Foucaran et Nicolas Camara. « Low-Cost Sensors for Indoor PV Energy Harvesting Estimation Based on Machine Learning ». Energies 15, n^o 3 (3 février 2022) : 1144. http://dx.doi.org/10.3390/en15031144.

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With the number of communicating sensors linked to the Internet of Things (IoT) ecosystem increasing dramatically, well-designed indoor light energy harvesting solutions are needed. A first step in this direction would be to be able to accurately estimate the harvestable energy in a specific light environment. However, inside, this energy varies in spectral composition and intensity, depending on the emission source as well as the time of day. These challenging conditions mean that it has become necessary to obtain accurate information about these variations and determine their impact on energy recovery performance. In this context, this manuscript presented a method to apply an innovative energy harvesting estimation method to obtain practical and accurate insight for the design of energy harvesting systems in indoor environments. It used a very low-cost device to obtain spectral information and fed it to supervised machine learning classification methods to recognize light sources. From the recognized light source, a model developed for flexible GaAs solar cells was able to estimate the harvestable energy. To validate this method in real indoor conditions, the estimates were compared to the energy harvested by an energy harvesting prototype. The mean absolute error percentage between estimates and the experimental measurements was less than 5% after more than 2 weeks of observation. This demonstrated the potential of this low-cost estimation system to obtain reliable information to design energetically autonomous devices.

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Wang, Shu-Ping, Yan-Feng Shen, Ben-Yue Zhu, Jing Wu et Shijun Li. « Recent advances in the template-directed synthesis of porphyrin nanorings ». Chemical Communications 52, n^o 67 (2016) : 10205–16. http://dx.doi.org/10.1039/c6cc04556a.

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This Feature Article reviews recent advances in the template-directed synthesis of porphyrin nanorings, including new templating methods, novel structures, and their applications in host–guest chemistry and artificial light-harvesting.

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de Bianchi, Silvia, Matteo Ballottari, Luca Dall’Osto et Roberto Bassi. « Regulation of plant light harvesting by thermal dissipation of excess energy ». Biochemical Society Transactions 38, n^o 2 (22 mars 2010) : 651–60. http://dx.doi.org/10.1042/bst0380651.

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Elucidating the molecular details of qE (energy quenching) induction in higher plants has proven to be a major challenge. Identification of qE mutants has provided initial information on functional elements involved in the qE mechanism; furthermore, investigations on isolated pigment–protein complexes and analysis in vivo and in vitro by sophisticated spectroscopic methods have been used for the elucidation of mechanisms involved. The aim of the present review is to summarize the current knowledge of the phenotype of npq (non-photochemical quenching)-knockout mutants, the role of gene products involved in the qE process and compare the molecular models proposed for this process.

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Zolotarev, V. N. « The influence of the timing and methods of harvesting the seed grass of the eastern goat’s rue (Galega orientales Lam.) on the yield and sowing quality of seeds ». IOP Conference Series : Earth and Environmental Science 901, n^o 1 (1 novembre 2021) : 012042. http://dx.doi.org/10.1088/1755-1315/901/1/012042.

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Abstract Eastern goat’s rue (Galega orientales Lam.) possesses high fodder productivity and accumulates a large amount of vegetative mass with high humidity for harvesting for seeds. This greatly complicates the harvesting of grass stand for seeds. One of the ways to solve this problem is to carry out desiccation of the grass stand. A complicating factor in choosing the optimal harvesting period is the extended flowering and ripening period of goat’s rue beans, the duration of which reaches 25-35 days. The use of the drug Reglon Super based on diquat is a highly effective agrotechnical method that allows increasing the collection of seeds by 24%. The desiccation of the herbage contributes to the production of seeds with high sowing qualities. The seeds with the best sowing qualities are found in beans with yellow, brown, brown or dark brown color of the beans. In light green beans, the seeds are fully formed, but have a high moisture content. Goat’s rue beans do not crack or crumble at the onset of the full ripeness phase. This allows the seed to be harvested when most of the beans are ripe. A comparative assessment of the timing and method of harvesting the seed herbage of the goat’s rue showed that with a ripening of 39% and the presence of 47% of light green and yellow beans, the yield losses ranged from 26 to 56%. The highest seed yield in one confidence interval of 422-453 kg / ha and 444 kg / ha was obtained, respectively, by direct threshing with preliminary desiccation of the grass stand in the ripening phase of 74-97% of beans or by separate harvesting when mowing into swaths during ripening 74 % beans.

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Obanawa, Hiroyuki, Rena Yoshitoshi, Nariyasu Watanabe et Seiichi Sakanoue. « Portable LiDAR-Based Method for Improvement of Grass Height Measurement Accuracy : Comparison with SfM Methods ». Sensors 20, n^o 17 (26 août 2020) : 4809. http://dx.doi.org/10.3390/s20174809.

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Plant height is a key indicator of grass growth. However, its accurate measurement at high spatial density with a conventional ruler is time-consuming and costly. We estimated grass height with high accuracy and speed using the structure from motion (SfM) and portable light detection and ranging (LiDAR) systems. The shapes of leaf tip surface and ground in grassland were determined by unmanned aerial vehicle (UAV)-SfM, pole camera-SfM, and hand-held LiDAR, before and after grass harvesting. Grass height was most accurately estimated using the difference between the maximum value of the point cloud before harvesting, and the minimum value of the point cloud after harvesting, when converting from the point cloud to digital surface model (DSM). We confirmed that the grass height estimation accuracy was the highest in DSM, with a resolution of 50–100 mm for SfM and 20 mm for LiDAR, when the grass width was 10 mm. We also found that the error of the estimated value by LiDAR was about half of that by SfM. As a result, we evaluated the influence of the data conversion method (from point cloud to DSM), and the measurement method on the accuracy of grass height measurement, using SfM and LiDAR.

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Kómar, Ladislav, et Miroslav Kocifaj. « An Accurate Prediction of Daylight Pipe Harvesting of Interior Space ». Applied Sciences 9, n^o 17 (29 août 2019) : 3552. http://dx.doi.org/10.3390/app9173552.

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The performance of a light guide under arbitrary meteorological conditions is difficult to predict numerically because none of the present methods can account for the random configuration of clouds. Although, partly cloudy skies typically occur very frequently in many regions over the globe, the effects of cloud sizes, distributions, or altitudes on the luminous effectiveness of a light guide remain virtually unknown. The physical installation of light guides does not allow for a controlled experiment in which a single parameter can be varied within a defined range, while holding all other parameters constant. Numerical modeling is the only practical way to provide deep insights on the role of a specific property, such as cloud coverage, and its importance relative to all others (e.g., atmospheric turbidity). We have developed a unique solution through linking the UniSky simulator and HOLIGILM (hollow light guide interior illumination method) tool, while providing for the first time a powerful method that can provide accurate predictions and understanding of the fundamental differences of light guide behaviors under homogeneous and inhomogeneous sky states. The use of homogeneous skies in low-accuracy empirical models often results in overestimated/underestimated effectiveness of some light-guide systems. The model we have developed can predict complex optical signatures that are normally impossible to reproduce using up-to date empirical models (e.g., the illuminance patterns due to isolated clouds or clouds traversing across the sky). The optical efficiency, average cosine and working-place illuminance are analyzed and compared in order to demonstrate the model capabilities.

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González-Soria, B., et F. Delgado. « Quantum Entanglement in Fenna—Matthews—Olson Photosynthetic Light—Harvesting complexes : A Short Review of Analysis Methods ». Journal of Physics : Conference Series 1540 (avril 2020) : 012026. http://dx.doi.org/10.1088/1742-6596/1540/1/012026.

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Tullus, Tea, Reimo Lutter, Tiina Randlane, Andres Saag, Arvo Tullus, Elle Roosaluste, Priit Kõresaar, Meelis Pärtel et Hardi Tullus. « Seventy-year history of management using low-intensity harvesting methods : weak impact on biodiversity of hemiboreal Scots pine forests ». Canadian Journal of Forest Research 50, n^o 12 (décembre 2020) : 1268–80. http://dx.doi.org/10.1139/cjfr-2020-0102.

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Less intensive harvesting methods (e.g., selection cutting, shelterwood cuttings) are recommended as alternatives to clearcutting for maintaining mature forest biodiversity in the process of forest regeneration. However, the long-term impact of low-intensity harvesting methods has rarely been studied. Our aim was to clarify the long-term effects of repeated selective cutting, thinning, and shelterwood cutting on the richness, abundance, and species composition of vascular plants, bryophytes, and lichens in Scots pine forests (Pinus sylvestris L.). Data were collected from 25 mature stands located in dry Podzols in southwestern Estonia with a known management history for the last 70 years. Altogether, 35 vascular plant, 41 bryophyte, and 78 lichen species were recorded, including five species with conservational value. Generally, the management history was not related to species richness, except a negative correlation with the species number of epiphytic lichens on conifer trees. In addition, the abundance of two lichen species from the genus Chaenotheca was lower in more frequently managed stands. Species richness and composition were most strongly affected by soil pH and light conditions. We conclude that long-term, low-intensity harvesting of Scots pine forests on nutrient-poor Podzols maintains suitable habitats for vascular plants, bryophytes, and lichens, confirming its suitability for sustainable forest regeneration.

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Kopacki, Marek, Joanna Pawłat, Barbara Skwaryło-Bednarz, Agnieszka Jamiołkowska, Patrycja Maria Stępniak, Piotr Kiczorowski et Katarzyna Golan. « Physical Crop Postharvest Storage and Protection Methods ». Agronomy 11, n^o 1 (6 janvier 2021) : 93. http://dx.doi.org/10.3390/agronomy11010093.

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Sustainable and organic plant production uses natural products and natural self-regulation processes occurring in the ecosystem. The awareness is growing and the demands of consumers are higher and higher. One solution is to use various methods, as an alternative to pesticides. It is also very important to care for the stored crops after harvesting especially using non-chemical methods. The physical method of plant protection consists in treating the harmful organism with physical factors such as temperature, its same light and radiation, controlled atmosphere, special packaging, pressure, various sounds, ozone, and low-temperature plasma. The availability of effective application techniques opens up new possibilities for the storage of crops in order to maintain their health and quality for a long time. This review focuses on the analysis of physical methods of postharvest protection, especially the latest methods using ozone and low-temperature plasma. As a result, consumers of agricultural crops will be able to consume food free of insects, mycotoxins and pesticide residues.

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Kang, Hanwen, Hongyu Zhou, Xing Wang et Chao Chen. « Real-Time Fruit Recognition and Grasping Estimation for Robotic Apple Harvesting ». Sensors 20, n^o 19 (4 octobre 2020) : 5670. http://dx.doi.org/10.3390/s20195670.

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Robotic harvesting shows a promising aspect in future development of agricultural industry. However, there are many challenges which are still presented in the development of a fully functional robotic harvesting system. Vision is one of the most important keys among these challenges. Traditional vision methods always suffer from defects in accuracy, robustness, and efficiency in real implementation environments. In this work, a fully deep learning-based vision method for autonomous apple harvesting is developed and evaluated. The developed method includes a light-weight one-stage detection and segmentation network for fruit recognition and a PointNet to process the point clouds and estimate a proper approach pose for each fruit before grasping. Fruit recognition network takes raw inputs from RGB-D camera and performs fruit detection and instance segmentation on RGB images. The PointNet grasping network combines depth information and results from the fruit recognition as input and outputs the approach pose of each fruit for robotic arm execution. The developed vision method is evaluated on RGB-D image data which are collected from both laboratory and orchard environments. Robotic harvesting experiments in both indoor and outdoor conditions are also included to validate the performance of the developed harvesting system. Experimental results show that the developed vision method can perform highly efficient and accurate to guide robotic harvesting. Overall, the developed robotic harvesting system achieves 0.8 on harvesting success rate and cycle time is 6.5 s.

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Irfan, Madiha, Aamer Saeed, Sabahat Akram et Sadia bin Yameen. « Dendrimers Chemistry and Applications : A Short Review ». FRONTIERS IN CHEMICAL SCIENCES 1, n^o 1 (30 juin 2020) : 31–41. http://dx.doi.org/10.52700/fcs.v1i1.6.

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Dendrimers, also known as cascade molecules, arborols, cauliflower or starburst polymers. They are monodisperse, symmetrical, macromolecules with tree like 3D-architecture consists of end-groups, central core and branching units associated to periphery and possess extremely constraint size, topography and surface characteristics like density, backfolding, intrinsic viscosity, light harvesting property, photophysical properties that are fairly distinct from linear polymers. Different types of dendrimers, on the basis of their different properties and associated functional groups, has been studied yet in which one of the unique group of dendrimers is dendrtic co-polymer possess two types, first are layer block dendrimers and second are segment block dendrimers. Some new types of dendrimers like IrC3, IrCl and IrF2 have been also synthesized by divergent or convergent methods of synthesis. Dendrimers have a lot of applications in different fields like nanotechnology, medical chemistry, light harvesting materials, as sensors, antibacterial and anti-microbial activity.

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Shrestha, Sika, Sun-Kuk Noh et Dong-You Choi. « Comparative Study of Antenna Designs for RF Energy Harvesting ». International Journal of Antennas and Propagation 2013 (2013) : 1–10. http://dx.doi.org/10.1155/2013/385260.

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In the last few years, several antenna designs of rectenna that meet various objectives have been proposed for use in RF energy harvesting. Among various antennas, microstrip patch antennas are widely used because of their low profile, light weight, and planar structure. Conventional patch antennas are rectangular or circular in shape, but variations in their basic design are made for different purposes. This paper begins with an explanation and discussion of different designs, put forward with an aim of miniaturization, harmonic rejection, and reconfigurability. Finally, microstrip patch structured rectennas are evaluated and compared with an emphasis on the various methods adopted to obtain a compact rectenna, harmonic rejection functionality, and frequency and polarization selectivity.

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Alazaiza, Motasem Y. D., Ahmed Albahnasawi, Tahra Al Maskari, Mohammed Shadi S. Abujazar, Mohammed J. K. Bashir, Dia Eddin Nassani et Salem S. Abu Amr. « Biofuel Production using Cultivated Algae : Technologies, Economics, and Its Environmental Impacts ». Energies 16, n^o 3 (26 janvier 2023) : 1316. http://dx.doi.org/10.3390/en16031316.

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The process of looking for alternative energy sources is driven by the increasing demand for energy and environmental contamination caused by using fossil fuels. Recent investigations reported the efficiency of microalgae for biofuel production due to its low cost of production, high speed of growth, and ability to grow in harsh environments. In addition, many microalgae are photosynthetic, consuming CO2 and solar light to grow in biomass and providing a promising bioenergy source. This review presents the recent advances in the application of microalgae for biofuel production. In addition, cultivation and harvesting systems and environmental factors that affect microalgae cultivation for biofuel production have also been discussed. Moreover, lipid extraction and conversion technologies to biofuel are presented. The mixotrophic cultivation strategy is promising as it combines the advantages of heterotrophy and autotrophy. Green harvesting methods such as using bio-coagulants and flocculants are promising technologies to reduce the cost of microalgal biomass production. In the future, more investigations into co-cultivation systems, new green harvesting methods, high lipids extraction methods, and the optimization of lipid extraction and converting processes should be implemented to increase the sustainability of microalgae application for biofuel production.

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Alkhabbas, Manal, Fadwa Odeh, Khitam Alzughoul, Razan Afaneh et Waed Alahmad. « Jordanian Kaolinite with TiO2 for Improving Solar Light Harvesting Used in Dye Removal ». Molecules 28, n^o 3 (18 janvier 2023) : 989. http://dx.doi.org/10.3390/molecules28030989.

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TiO2–Kaolinite nanocomposite photocatalysts were synthesized using the sol–gel method, with titanium isopropoxide/HCl as reactants and Jordanian kaolinite clay as a support material. The samples’ TiO2 content ranged from 10% to 70% (m/m). TiO2–Kaolinite composites were characterized using FTIR, SEM, XRF, and XRD. According to XRD measurements of the nano-composite samples, the intensity of the anatase peaks increased as the TiO2 percentage of the composition increased. As the percentage of TiO2 increased, so did the peaks of Ti–O–Si in FTIR. The extent of photocatalytic degradation of Congo-red dye was used to evaluate the photocatalytic activity of the prepared nanocomposites. After four hours under the sun, the percentage of Congo-red degradation ranged from 27 to 99 percent depending on the TiO2 content of the used nanocomposite. Meanwhile, the concentration drop in the dark did not exceed 10%. Photodegradation outperforms traditional treatment methods in terms of target degradation. Using naturally abundant materials such as clay in conjunction with metal oxides is widely regarded as an effective method of modifying the photoresponse properties of TiO2 particles, thereby improving solar light harvesting for target degradation.

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McLuskey, Karen, Stephen M. Prince, Richard J. Cogdell et Neil W. Isaacs. « Crystallization and preliminary X-ray crystallographic analysis of the B800–820 light-harvesting complex from Rhodopseudomonas acidophila strain 7050 ». Acta Crystallographica Section D Biological Crystallography 55, n^o 4 (1 avril 1999) : 885–87. http://dx.doi.org/10.1107/s0907444998016059.

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The B800–820 peripheral light-harvesting complex, an integral membrane protein from Rhodopseudomonas acidophila strain 7050, has been crystallized in a form suitable for X-ray diffraction analysis. The crystals belong to space group R32 with hexagonal cell dimensions a = 117.20, c = 295.14 Å (at 100 K). A complete 2.8 Å resolution data set has been collected and a structure solution obtained using molecular-replacement methods.

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Feighan, Oliver, Frederick R. Manby et Susannah Bourne-Worster. « An efficient protocol for excited states of large biochromophores ». Journal of Chemical Physics 158, n^o 2 (14 janvier 2023) : 024107. http://dx.doi.org/10.1063/5.0132417.

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Efficient energy transport in photosynthetic antenna is a long-standing source of inspiration for artificial light harvesting materials. However, characterizing the excited states of the constituent chromophores poses a considerable challenge to mainstream quantum chemical and semiempirical excited state methods due to their size and complexity and the accuracy required to describe small but functionally important changes in their properties. In this paper, we explore an alternative approach to calculating the excited states of large biochromophores, exemplified by a specific method for calculating the Q y transition of bacteriochlorophyll a, which we name Chl-xTB. Using a diagonally dominant approximation to the Casida equation and a bespoke parameterization scheme, Chl-xTB can match time-dependent density functional theory’s accuracy and semiempirical speed for calculating the potential energy surfaces and absorption spectra of chlorophylls. We demonstrate that Chl-xTB (and other prospective realizations of our protocol) can be integrated into multiscale models, including concurrent excitonic and point-charge embedding frameworks, enabling the analysis of biochromophore networks in a native environment. We exploit this capability to probe the low-frequency spectral densities of excitonic energies and interchromophore interactions in the light harvesting antenna protein LH2 (light harvesting complex 2). The impact of low-frequency protein motion on interchromophore coupling and exciton transport has routinely been ignored due to the prohibitive costs of including it in simulations. Our results provide a more rigorous basis for continued use of this approximation by demonstrating that exciton transition energies are unaffected by low-frequency vibrational coupling to exciton interaction energies.

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Belov, A. S., D. V. Khokhlov et V. V. Poddubnyi. « Comparison of the accuracy of approximate methods TrESP and TrCAMM for evaluation of pigment coupling in light-harvesting complexes ». Doklady Physical Chemistry 468, n^o 1 (mai 2016) : 63–66. http://dx.doi.org/10.1134/s0012501616050018.

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Fathy, Wael, Khaled Elsayed, Ehab Essawy, Eman Tawfik, Ayman Zaki, Mohamed S. Abdelhameed et Ola Hammouda. « Biosynthesis of Silver Nanoparticles from Synechocystis sp to be Used as a Flocculant Agent with Different Microalgae Strains ». Current Nanomaterials 5, n^o 2 (26 octobre 2020) : 175–87. http://dx.doi.org/10.2174/2468187310999200605161200.

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Background: Biofuels produced from trans-esterification of high lipid content in microalgae represent a promising alternative renewable source of energy to the limited and depleted global fossil fuel reservoir. The most critical step in such a process is the harvesting of algal cells. Objective: We aimed to improve the current methodology for microalgae harvesting via utilizing biosynthesized silver nanoparticles (AgNPs) from Synechocystis sp. ElfSCS31 as an eco-friendly, stable, and affordable flocculant agent. Methods: AgNPs were prepared by the green synthesis method using the alcoholic extract of Synechocystis sp. ElfSCS31. The synthesized nanoparticles were characterized by Zeta sizer, X-ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FT-IR), and UV-Vis Spectroscopy. Biosynthesised AgNPs were applied for harvesting 20 microalgae strains, and then, harvesting efficiency was determined by UV Spectrophotometry. Results: Our results revealed an average size of polydispersed nanoparticles ranging from 10 to 100 nm for prepared AgNPs and the potential of 1.78 mV, with an average crystallite size of 22 nm. Biosynthesised AgNPs exhibited harvesting efficiency towards different strains of microalgae, which reached 97% in some strains as in Chlorella lobophora and Chlorococcum oleofaciens. Conclusion: The presented study introduces a feasible strategy using biosynthesized AgNPs as a flocculant agent to harvest different strains of microalgae at normal growth conditions of light and temperature. Our developed method could replace the classical high-cost step of harvesting that leads to unravelling the full potential of microalgae as a promising and fascinating source for biofuels production.

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Kouao, Dujearic-Stephane, Katarzyna Grochowska et Katarzyna Siuzdak. « The Anodization of Thin Titania Layers as a Facile Process towards Semitransparent and Ordered Electrode Material ». Nanomaterials 12, n^o 7 (29 mars 2022) : 1131. http://dx.doi.org/10.3390/nano12071131.

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Photoanodes consisting of titania nanotubes (TNTs) grown on transparent conductive oxides (TCO) by anodic oxidation are being widely investigated as a low-cost alternative to silicon-based materials, e.g., in solar light-harvesting applications. Intending to enhance the optical properties of those photoanodes, the modification of the surface chemistry or control of the geometrical characteristics of developed TNTs has been explored. In this review, the recent advancement in light-harvesting properties of transparent anodic TNTs formed onto TCO is summarized. The physical deposition methods such as magnetron sputtering, pulsed laser deposition and electron beam evaporation are the most reported for the deposition of Ti film onto TCO, which are subsequently anodized. A concise description of methods utilized to improve the adhesion of the deposited film and achieve TNT layers without cracks and delamination after the anodization is outlined. Then, the different models describing the formation mechanism of anodic TNTs are discussed with particular focus on the impact of the deposited Ti film thickness on the adhesion of TNTs. Finally, the effects of the modifications of both the surface chemistry and morphological features of materials on their photocatalyst and photovoltaic performances are discussed. For each section, experimental results obtained by different research groups are evoked.

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Song, Bing Cong, Lan Ching Sim, Yik Heng Chin, Ling Yong Wong, Pichiah Saravanan, Chaomeng Dai et Kah Hon Leong. « Amalgamation of g-C₃N₄ with KNbO₃ for enhanced removal of Bisphenol A under sunlight irradiation ». IOP Conference Series : Earth and Environmental Science 945, n^o 1 (1 décembre 2021) : 012052. http://dx.doi.org/10.1088/1755-1315/945/1/012052.

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Abstract Bisphenol A (BPA) is a pollutant exits in an enormous amount in wastewater effluent resulted from the rapid industrialization. Advanced oxidation technology (AOP) based on solar photocatalysis can be employed to solve this issue. This study will focus on adopting photocatalyst graphitic carbon nitride (g-C3N4) with potassium niobate (KNbO3) via a simple sol-gel synthesis method. The different weight percentages 0.5, 1.0 and 1.5 wt% g-C3N4, were adopted to formed KNbO3/g-C3N4composites. The physicochemical properties of the created KNbO3/g-C3N4composites were characterized with advanced analysis methods to unveil this composite’s ability to enhance the photodegradation of BPA under sunlight irradiation. It was found that 1.0 wt% KNbO3/g-C3N4composites exhibited the highest photocatalytic degradation of 69.39% in 5 h. This superior photodegradation of BPA was achieved resulted from the presence of g-C3N4that enhances light-harvesting, especially in the visible light spectrum. The increase of light-harvesting enables the composite to excite more electrons and holes leading to the massive formation of active radicals. These massive active radicals will then enhance the redox reaction and further improve the efficacy of the photodegradation of BPA. Hence, the outcome of this study path an alternative solution for eliminating complex organic pollutants in wastewater treatment.

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Baktemur, Gökhan, Hatıra Taşkın et Saadet Büyükalaca. « Comparison of Different Methods for Separation of Haploid Embryo Induced through Irradiated Pollen and Their Economic Analysis in Melon (Cucumis melovar.inodorus) ». Scientific World Journal 2013 (2013) : 1–7. http://dx.doi.org/10.1155/2013/529502.

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Irradiated pollen technique is the most successful haploidization technique withinCucurbitaceae. After harvesting of fruits pollinated with irradiated pollen, classical method called as “inspecting the seeds one by one” is used to find haploid embryos in the seeds. In this study, different methods were used to extract the embryos more easily, quickly, economically, and effectively. “Inspecting the seeds one by one” was used as control treatment. Other four methods tested were “sowing seeds direct nutrient media,” “inspecting seeds in the light source,” “floating seeds on liquid media,” and “floating seeds on liquid media after surface sterilization.” Y2 and Y3 melon genotypes selected from the third backcross population of Yuva were used as plant material. Results of this study show that there is no statistically significant difference among methods “inspecting the seeds one by one,” “sowing seeds direct CP nutrient media,” and “inspecting seeds in the light source,” although the average number of embryos per fruit is slightly different. No embryo production was obtained from liquid culture because of infection. When considered together with labor costs and time required for embryo rescue, the best methods were “sowing seeds directly in the CP nutrient media“ and ”inspecting seeds in the light source.”

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Odiyur Vathanam, Gnana Swathika, Karthikeyan Kalyanasundaram, Rajvikram Madurai Elavarasan, Shabir Hussain Khahro, Umashankar Subramaniam, Rishi Pugazhendhi, Mehana Ramesh et Rishi Murugesan Gopalakrishnan. « A Review on Effective Use of Daylight Harvesting Using Intelligent Lighting Control Systems for Sustainable Office Buildings in India ». Sustainability 13, n^o 9 (29 avril 2021) : 4973. http://dx.doi.org/10.3390/su13094973.

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Lighting is a fundamental requirement of our daily life. A lot of research and development is carried out in the field of daylight harvesting, which is the need of the hour. One of the most desirable attributes of daylight harvesting is that daylight is available universally and it is a very clean and cost-efficient form of energy. By using the various methods of daylight harvesting, it is possible to attain the global Sustainable Development Goals. Daylight harvesting in the most fundamental sense is the lighting strategy control of the artificial light in an interior space where daylight is also present so that the required illumination level is achieved. This way, a lot of energy can be saved. Recently, in addition to energy efficiency, other factors such as cost-efficiency, user requirements such as uniform illuminance, and different levels of illuminance at different points are being considered. To simulate the actual daylight contribution for an office building in urban Chennai, India before construction, ECO TECH software is used by providing the inputs such as building orientation, and reflectance’s values of the ceiling, wall, and floor to analyze the overall percentage of daylight penetration available versus the percentage prescribed in the Indian Green Building Council to obtain the credit points. Thus, the impact of architectural design on daylight harvesting and daylight predictive technology has experimented with office building in Chennai, India. This article will give an insight into the current trends in daylight harvesting technology and intends to provide a deeper understanding and spark a research interest in this widely potential field.

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El-Khouly, Mohamed E., Maged A. El-Kemary, Ahmed El-Refaey, Kwang-Yol Kay et Shunichi Fukuzumi. « Light harvesting subphthalocyanine–ferrocene dyads : Fast electron transfer process studied by femtosecond laser photolysis ». Journal of Porphyrins and Phthalocyanines 20, n^o 08n11 (août 2016) : 1148–55. http://dx.doi.org/10.1142/s1088424616500784.

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Ferrocene-subphthalocyanine dyads characterized, where ferrocene is axially linked with subphthalocyanine at its axial position with the B–O bond through the para and metapositions, namely Fc–[Formula: see text]PhO–SubPc (dyad 1) and Fc–[Formula: see text]PhO–SubPc (dyad 2). The geometric and electronic structures of 1 and 2 were probed by ab initio B3LYP/6-311G methods. The optimized structures showed that the Fc and SubPc entities are separated by 8.42 and 7.40 Å for dyads 1 and2, respectively. The distribution of the highest occupied frontier molecular orbital (HOMO) was found to be located on the Fc entity, while the lowest unoccupied molecular orbital (LUMO) was located on the SubPc entity, suggesting that the charge-separated states of the are Fc[Formula: see text]–SubPc[Formula: see text]. Upon photoexcitation at the subphthalocyanine unit, both dyads undergo photoinduced electron transfer to form the corresponding charge-separated species, Fc[Formula: see text]–SubPc[Formula: see text]. Based on their redox potentials determined by cyclic voltammetry technique, the direction of the charge separation and the energies of these states have been revealed. Femtosecond transient spectroscopic studies have revealed that a fast charge separation of 8.8 × 10[Formula: see text] and 1.2 × 10[Formula: see text] s[Formula: see text] for 1 and 2, respectively, indicating fast charge separation in these simple dyads.

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Nam, Myeong Hyeon, Hyun Sook Kim, InHa Lee, Jeong Hak Seo et Byung Joo Lee. « Suppression of Powdery Mildew and Two-Spotted Spider Mite by UV-B Radiation and Mulching Type of Strawberry Cultivation in the Greenhouse ». Research in Plant Disease 28, n^o 2 (30 juin 2022) : 61–68. http://dx.doi.org/10.5423/rpd.2022.28.2.61.

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Powdery mildew and two-spotted spider mite are detrimental to strawberry plants and are controlled with traditional pesticides. To accommodate consumer demand, eco-friendly methods of pest control are required. Strawberries were cultivated (in soil and in a hydroponic system) for two years, and ultraviolet B (UV-B) irradiation was used as an alternative pest control during the harvesting season. Three varieties were grown (Seolhyang, Kingsberry, and Durihyang), and four UV-B lamp/mulch (black, green, and light reflection sheet [LRS]) combinations were used during harvesting: UV-B+black or green mulch, UV-B+black or green+LRS, no UV-B+black or green, and no UV-B+black or green+LRS. In all varieties, powdery mildew was 65% more controlled when UV-B irradiation was used. The adult two-spotted spider mite density was lowest in the UV-B lamp+black or green+LRS treatments. Therefore, UV-B irradiation during the strawberry harvesting season could effectively control powdery mildew and two-spotted spider mite with little side effect on the plants.

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Lukyanenko, Petro. « Change of status of stems indicators in the process of healing of stock after hemp seeds harvesting with a grain harvester for different technologies ». Bast and Technical Crops, n^o 7(12) (1 décembre 2019) : 58–63. http://dx.doi.org/10.48096/btc.2019.7(12).58-63.

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The aim is to study the indicators of changes in the state of stems in the process of stocks retting after hemp seeds harvesting with a combine harvester using various technologies. A brief description of the work performed. With two methods of hemp seeds harvesting by a combine harvester by cutting the seed part and combing it with subsequent threshing, it was investigated that during the preparation of the stocks, the state of all constituent stems, namely, left standing, after the harvesting process is carried out, is in the wheel area and threshed in the thresher for option with a cut. It was established that during the preparation of hemp stocks after harvesting the seeds with a combine harvester, the color of the stems changes from yellow-green (corresponds to straw) to gray with slight brown shades, which corresponds to the stock for all components. The color change of the stems during the preparation of the stock can be controlled by the indicator of the intensity of the reflected light flux from the test surface, which decreases and for straw corresponds to 46-54 lux, the beginning of the formation of the stock, when on the first stems the fiber begins to separate from the wood - 30-32 lux and matted stock - 25-28 lux. Conclusions. Indicators of changes in the state of stems in the process of maturing stocks after hemp seeds harvesting with a combine harvester using different technologies are determined.

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González-Soria, Bruno, Francisco Delgado et Alan Anaya-Morales. « Parametric Mapping of Quantum Regime in Fenna–Matthews–Olson Light-Harvesting Complexes : A Synthetic Review of Models, Methods and Approaches ». Applied Sciences 10, n^o 18 (17 septembre 2020) : 6474. http://dx.doi.org/10.3390/app10186474.

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Developments in ultrafast-spectroscopy techniques have revealed notably long-lived quantum coherence between electronic states in Fenna–Matthews–Olson complex bacteriochlorophylls, a group of molecules setting a nanoscale structure responsible of the coherent energy transfer in the photosynthetic process of green sulfur bacteria. Despite the experimental advances, such a task should normally be complemented with physical computer simulations to understand its complexity. Several methods have been explored to model this quantum phenomenon, mainly using the quantum open systems theory as a first approach. The traditional methods used in this approach do not take into account the memory effects of the surroundings, which is commonly approximated as a phonon bath on thermal equilibrium. To surpass such an approximation, this article applies the Hierarchical Equations of Motion method, a non-markovian approach also used to analyze the dynamic of such a complex, for the modeling of the system evolution. We perform a parametric analysis about some physical features in the quantum regime involved during the quantum excitation process in order to get a comprehension about its non-trivial dependence on operation parameters. Thus, the analysis is conducted in terms of some relevant physical parameters in the system to track the complex global behavior in aspects as coherence, entanglement, decoherence times, transference times, and efficiency of the main process of energy capturing. As a complementary analysis from the derived outcomes, we compare those features for two different species as a suggestive possible roadmap to track genetic differences in the photosynthetic performance of the complex through its biological nature.

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D Stevens, Joseph, David Murray, Dean Diepeveen et Danny Toohey. « Adaptalight : An Inexpensive PAR Sensor System for Daylight Harvesting in a Micro Indoor Smart Hydroponic System ». Horticulturae 8, n^o 2 (25 janvier 2022) : 105. http://dx.doi.org/10.3390/horticulturae8020105.

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Environmental changes and the reduction in arable land have led to food security concerns around the world, particularly in urban settings. Hydroponic soilless growing methods deliver plant nutrients using water, conserving resources and can be constructed nearly anywhere. Hydroponic systems have several complex attributes that need to be managed, and this can be daunting for the layperson. Micro Indoor Smart Hydroponics (MISH) leverage Internet of Things (IoT) technology to manage the complexities of hydroponic techniques, for growing food at home for everyday citizens. Two prohibitive costs in the advancement of MISH systems are power consumption and equipment expense. Reducing cost through harvesting ambient light can potentially reduce power consumption but must be done accurately to sustain sufficient plant yields. Photosynthetic Active Radiation (PAR) meters are commercially used to measure only the light spectrum that plants use, but are expensive. This study presents Adaptalight, a MISH system that harvests ambient light using an inexpensive AS7265x IoT sensor to measure PAR. The system is built on commonly found IoT technology and a well-established architecture for MISH systems. Adpatalight was deployed in a real-world application in the living space of an apartment and experiments were carried out accordingly. A two-phase experiment was conducted over three months, each phase lasting 21 days. Phase one measured the IoT sensor’s capability to accurately measure PAR. Phase two measured the ability of the system to harvest ambient PAR light and produce sufficient yields, using the calibrated IoT sensor from phase one. The results showed that the Adaptalight system was successful in saving a significant amount of power, harvesting ambient PAR light and producing yields with no significant differences from the control. The amount of power savings would be potentially greater in a location with more ambient light. Additionally, the findings show that, when calibrated, the AS7265x sensor is well suited to accurately measure PAR light in MISH systems.

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Qin, Kezhen, Alisdair R. Fernie et Youjun Zhang. « The Assembly of Super-Complexes in the Plant Chloroplast ». Biomolecules 11, n^o 12 (7 décembre 2021) : 1839. http://dx.doi.org/10.3390/biom11121839.

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Increasing evidence has revealed that the enzymes of several biological pathways assemble into larger supramolecular structures called super-complexes. Indeed, those such as association of the mitochondrial respiratory chain complexes play an essential role in respiratory activity and promote metabolic fitness. Dynamically assembled super-complexes are able to alternate between participating in large complexes and existing in a free state. However, the functional significance of the super-complexes is not entirely clear. It has been proposed that the organization of respiratory enzymes into super-complexes could reduce oxidative damage and increase metabolism efficiency. There are several protein complexes that have been revealed in the plant chloroplast, yet little research has been focused on the formation of super-complexes in this organelle. The photosystem I and light-harvesting complex I super-complex’s structure suggests that energy absorbed by light-harvesting complex I could be efficiently transferred to the PSI core by avoiding concentration quenching. Here, we will discuss in detail core complexes of photosystem I and II, the chloroplast ATPase the chloroplast electron transport chain, the Calvin–Benson cycle and a plastid localized purinosome. In addition, we will also describe the methods to identify these complexes.

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Al-Attafi, Kadhim, Andrew Nattestad, Shi Dou et Jung Kim. « A Comparative Study of TiO2 Paste Preparation Methods Using Solvothermally Synthesised Anatase Nanoparticles in Dye-Sensitised Solar Cells ». Applied Sciences 9, n^o 5 (8 mars 2019) : 979. http://dx.doi.org/10.3390/app9050979.

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Dye-sensitised solar cells continue to be a promising photovoltaic technology for indoor and outdoor applications, with increased interest in power window applications integrated into buildings. This results from properties not seen in other, more established solar technologies, such as the range of available colours, partial transparency and good performance under low light intensities or in partial shade. In spite of the attractiveness of this application and the commercial availability of suitable non-scattering TiO2 materials, the vast majority of new TiO2 materials being developed and reported in the literature are dried prior to being made into a paste and subsequently into photoanode films. Here, we make a detailed side-by-side comparison of different paste-forming techniques, with one yielding scattering films, and the other yielding non-scattering films. Devices utilising the organic dye D149 showed comparable performance using both approaches (6.9% photovoltaic conversion efficiency (PCE) with drying versus 6.4% PCE without drying), while the difference was slightly more marked with the dye N719 (7.7% PCE versus 6.8% PCE), suggesting that the trade-off in light harvesting required for power windows may be acceptably small. We also discuss ways by which these differences may be further decreased.

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Kang, Soon Hyung. « (Invited) Photoelectrochemical Energy Materials and Device ». ECS Meeting Abstracts MA2022-01, n^o 36 (7 juillet 2022) : 1596. http://dx.doi.org/10.1149/ma2022-01361596mtgabs.

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Nowadays, the exploration of new photoelectrode architectures to improve the light-harvesting and charge-collection properties of photoelectrochemical cells and related devices have been regarded as a challenging work. The efficient, stable, visible light absorption and cost effective photoelectrode materials are certainly important in developing highly efficient PEC system. Here, we synthesized the various metal oxide and nitrides for photoelectrochemical water splitting. Based on their synthesis methods and intrinsic properties, we tested the possibility(large-scale and stability) toward their PEC applications. Related deep insight would be discussed in terms of the fundamental analyses and reasonable results based on the theoretical background to give an meaningful potential for the future PEC world.

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ŞAHİN, Mustafa, Elçin KILIÇ et Etem OSMA. « The Effects of Light Produced in Different Ways on Triticum aestivum L. (Wheat) and Hordeum vulgare L. (Barley) ». Erzincan Üniversitesi Fen Bilimleri Enstitüsü Dergisi 15, n^o 3 (30 décembre 2022) : 916–30. http://dx.doi.org/10.18185/erzifbed.1093191.

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The ways of producing light with lighting equipment used in agricultural practice are different from each other. Therefore, each method of production generates light with different physical properties. This creates different effects on plants and living creatures. In this study, the effect of light produced by commonly used methods such as incandescence, electric discharge and electroluminescence on T. aestivum L. (wheat) and H. vulgare L. (barley) were analysed. For this purpose, different lighting environments where sources of light with LED, incandescence, sodium vapour, mercury vapour and metal halide discharge were used were created, and all variables except for the sources of light were kept the same. Wheat and barley were grown in these environments, and after the growth and harvesting processes had been completed, wet weight values, linear measurements, amounts of electrolyte leakage, chlorophyll, carotene, SOD (superoxide dismutase) and (CAT) Catalase enzyme activities were determined. Differences between the plants grown under the light parameters were determined by evaluating the data with SPSS. There were statistically significant differences between the data obtained from wheat and barley grown under different lamps.

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Cooke, Daniel L., Hua Su, Zhengda Sun, Yi Guo, Diana Guo, Maythem M. Saeed, Steven W. Hetts et al. « Endovascular Biopsy : Evaluating the Feasibility of Harvesting Endothelial Cells Using Detachable Coils ». Interventional Neuroradiology 19, n^o 4 (décembre 2013) : 399–408. http://dx.doi.org/10.1177/159101991301900401.

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The absence of safe and reliable methods to harvest vascular tissue in situ limits the discovery of the underlying genetic and pathophysiological mechanisms of many vascular disorders such as aneurysms. We investigated the feasibility and comparable efficacy of endothelial cell collection using a spectrum of endovascular coils. Nine detachable coils ranging in k coefficient (0.15–0.24), diameter (4.0 mm–16.0 mm), and length (8.0 cm–47.0 cm) were tested in pigs. All coils were deployed and retrieved within the iliac artery of pigs (three coils/pig). Collected coils were evaluated under light microscopy. The total and endothelial cells collected by each coil were quantified. The nucleated cells were identified by Wright-Giemsa and DAPI stains. Endothelial and smooth muscle cells were identified by CD31 and α-smooth muscle actin antibody staining. Coils were deployed and retrieved without technical difficulty. Light microscopy demonstrated sheets of cellular material concentrated within the coil winds. All coils collected cellular material while five of nine (55.6%) coils retrieved endothelial cells. Coils collected mean endothelial cell counts of 89.0±101.6. Regression analysis demonstrated a positive correlation between increasing coil diameter and endothelial cell counts (R2 = 0.52, p = 0.029). Conventional detachable coils can be used to harvest endothelial cells. The number of endothelial cells collected by a coil positively correlated with its diameter. Given the widespread use of coils and their well-described safety profile their potential as an endovascular biopsy device would expand the availability of tissue for cellular and molecular analysis.

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Osella, Silvio. « Artificial Photosynthesis : Is Computation Ready for the Challenge Ahead ? » Nanomaterials 11, n^o 2 (24 janvier 2021) : 299. http://dx.doi.org/10.3390/nano11020299.

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A tremendous effort is currently devoted to the generation of novel hybrid materials with enhanced electronic properties for the creation of artificial photosynthetic systems. This compelling and challenging problem is well-defined from an experimental point of view, as the design of such materials relies on combining organic materials or metals with biological systems like light harvesting and redox-active proteins. Such hybrid systems can be used, e.g., as bio-sensors, bio-fuel cells, biohybrid photoelectrochemical cells, and nanostructured photoelectronic devices. Despite these efforts, the main bottleneck is the formation of efficient interfaces between the biological and the organic/metal counterparts for efficient electron transfer (ET). It is within this aspect that computation can make the difference and improve the current understanding of the mechanisms underneath the interface formation and the charge transfer efficiency. Yet, the systems considered (i.e., light harvesting protein, self-assembly monolayer and surface assembly) are more and more complex, reaching (and often passing) the limit of current computation power. In this review, recent developments in computational methods for studying complex interfaces for artificial photosynthesis will be provided and selected cases discussed, to assess the inherent ability of computation to leave a mark in this field of research.

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Manrique, Pedro D., Ferney Rodríguez, Luis Quiroga et Neil F. Johnson. « Nonequilibrium Quantum Systems : Divergence between Global and Local Descriptions ». Advances in Condensed Matter Physics 2015 (2015) : 1–7. http://dx.doi.org/10.1155/2015/615727.

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Even photosynthesis—the most basic natural phenomenon underlying life on Earth—involves the nontrivial processing of excitations at the pico- and femtosecond scales during light-harvesting. The desire to understand such natural phenomena, as well as interpret the output from ultrafast experimental probes, creates an urgent need for accurate quantitative theories of open quantum systems. However it is unclear how best to generalize the well-established assumptions of an isolated system, particularly under nonequilibrium conditions. Here we compare two popular approaches: a description in terms of a direct product of the states of each individual system (i.e., alocalapproach) versus the use of new states resulting from diagonalizing the whole Hamiltonian (i.e., aglobalapproach). The main difference lies in finding suitable operators to derive the Lindbladian and hence the master equation. We show that their equivalence fails when the system is open, in particular under the experimentally ubiquitous condition of a temperature gradient. By solving for the steady state populations and calculating the heat flux as a test observable, we uncover stark differences between the formulations. This divergence highlights the need to establish rigorous ranges of applicability for such methods in modeling nanoscale transfer phenomena—including during the light-harvesting process in photosynthesis.

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Silva, Pedro J., Maria Osswald-Claro et Rosário Castro Mendonça. « How to tune the absorption spectrum of chlorophylls to enable better use of the available solar spectrum ». PeerJ Physical Chemistry 4 (19 décembre 2022) : e26. http://dx.doi.org/10.7717/peerj-pchem.26.

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Photon capture by chlorophylls and other chromophores in light-harvesting complexes and photosystems is the driving force behind the light reactions of photosynthesis. Excitation of photosystem II allows it to receive electrons from the water-oxidizing oxygen-evolution complex and to transfer them to an electron-transport chain that generates a transmembrane electrochemical gradient and ultimately reduces plastocyanin, which donates its electron to photosystem I. Subsequently, excitation of photosystem I leads to electron transfer to a ferredoxin which can either reduce plastocyanin again (in so-called “cyclical electron-flow”) and release energy for the maintenance of the electrochemical gradient, or reduce NADP+ to NADPH. Although photons in the far-red (700–750 nm) portion of the solar spectrum carry enough energy to enable the functioning of the photosynthetic electron-transfer chain, most extant photosystems cannot usually take advantage of them due to only absorbing light with shorter wavelengths. In this work, we used computational methods to characterize the spectral and redox properties of 49 chlorophyll derivatives, with the aim of finding suitable candidates for incorporation into synthetic organisms with increased ability to use far-red photons. The data offer a simple and elegant explanation for the evolutionary selection of chlorophylls a, b, c, and d among all easily-synthesized singly-substituted chlorophylls, and identified one novel candidate (2,12-diformyl chlorophyll a) with an absorption peak shifted 79 nm into the far-red (relative to chlorophyll a) with redox characteristics fully suitable to its possible incorporation into photosystem I (though not photosystem II). chlorophyll d is shown by our data to be the most suitable candidate for incorporation into far-red utilizing photosystem II, and several candidates were found with red-shifted Soret bands that allow the capture of larger amounts of blue and green light by light harvesting complexes.

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Lee, Sher Ling, et Chi-Jung Chang. « Recent Progress on Metal Sulfide Composite Nanomaterials for Photocatalytic Hydrogen Production ». Catalysts 9, n^o 5 (17 mai 2019) : 457. http://dx.doi.org/10.3390/catal9050457.

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Metal sulfide-based photocatalysts have gained much attention due to their outstanding photocatalytic properties. This review paper discusses recent developments on metal sulfide-based nanomaterials for H2 production, acting as either photocatalysts or cocatalysts, especially in the last decade. Recent progress on key experimental parameters, in-situ characterization methods, and the performance of the metal sulfide photocatalysts are systematically discussed, including the forms of heterogeneous composite photocatalysts, immobilized photocatalysts, and magnetically separable photocatalysts. Some methods have been studied to solve the problem of rapid recombination of photoinduced carriers. The electronic density of photocatalysts can be investigated by in-situ C K-edge near edge X-ray absorption fine structure (NEXAFS) spectra to study the mechanism of the photocatalytic process. The effects of crystal properties, nanostructure, cocatalyst, sacrificial agent, electrically conductive materials, doping, calcination, crystal size, and pH on the performance of composite photocatalysts are presented. Moreover, the facet effect and light trapping (or light harvesting) effect, which can improve the photocatalytic activity, are also discussed.

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