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- 2017
- photosynthesis
- dry matter
- gas exchange
- chlorophyll content
- ozone layer.
- Agronomy
- University of Basilicata
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Do optical sensor readings change throughout the day? An evaluation of two sensor systems
摘要： Optical sensors are useful tools for rapid and periodic assessment of plant nutritional status. However, the utility and potential of these sensors may be reduced if their readings change throughout the day. Therefore, this study aimed to assess the effects of time of day on measurements of the SPAD-502 chlorophyll meter and the GreenSeeker throughout the bean crop cycle. The treatments consisted of time of day for sensor measurements (8:00, 12:00, and 16:00 h) throughout six dates over the crop cycle. The results showed that measurements from the SPAD-502 and the GreenSeeker significantly changed according to time of day. The SPAD index at 16:00 h showed the lowest coefficient of variation (CV, 2.5%) and was on average, 3.05 ± 0.43, and 1.12 ± 0.25 SPAD units higher when compared to readings obtained at 8:00 and 12:00 h. Differently, the NDVI from the GreenSeeker showed the lowest CV (4.34%) at 8:00 h and was, on average, 0.06 ± 0.028 and 0.03 ± 0.01 units higher than measurements taken at 16:00 h and 12:00 h, respectively. Furthermore, the different times of sensor measurements present variations in air temperature and solar radiation, which directly influence the leaf water content and paraheliotropic movements. Thus, the indices from both sensors tend to show a high variability during different times of the day. Therefore, it is essential to create a consistent sampling protocol to reduce the variability of sensor measurements during the crop cycle.
关键词： Phaseolus vulgaris L,solar radiation,chlorophyll meter,precision agriculture,canopy reflectance sensor
更新于2025-09-19 17:13:59
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The sensitization effect of anthocyanin and chlorophyll dyes on optical and photovoltaic properties of zinc oxide based dye-sensitized solar cells
摘要： In this work, natural dyes based on anthocyanin and chlorophyll pigments were extracted from the powder of P. rubra flowers and S. androgynous leave respectively and used as sensitizers to fabricate zinc oxide (ZnO) based dye-sensitized solar cell (DSSC). It was observed in optical properties analysis that anthocyanin molecules formed a better bond with ZnO surface compared to chlorophyll. Moreover, anthocyanin sensitized ZnO also exhibits higher increment in nanoparticles diameter compared to that of chlorophyll sensitized ZnO due to the chemical absorption occurant. The anthocyanin sensitized DSSC also shows better photovoltaic performance with power conversion efficiency (PCE) of 0.038% compared to chlorophyll sensitized DSSC which exhibited PCE value of 0.014% due to better charges transfer at the interface between the dye molecule and ZnO nanoparticle.
关键词： photovoltaic performances,optical properties,chlorophyll,anthocyanin
更新于2025-09-16 10:30:52
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Effect of Electrical Resistance of TiO<sub>2</sub> Layer Characteristics of Dye Sensitized Solar Cell Using Chlorophyll as a Sensitizer
摘要： The third generation of solar cells found by Gratzel in 1991 was called Dye-sensitized Solar Sell (DSSC). DSSC is composed of five parts, namely transparent conductive glass as a substrat; titanium dioxide as a semiconductor materials; chlorophyll as a dye sensitizer, carbon as a catalyst which can convert energy of light into electrical energy. Characterization of DSSC will be carried out in this research covering electrical characterization using RLC meter & I-V meter, optical characterization using Spectrophotometer. TiO2 nanoparticle in anatase phase having size of 13 nm used in this experiment was synthesized by co-precipitation method. Photoanode with thickness of 10 μm has the lowest resistance compared to the other thickness of 30 μm and 50 μm. The device applying photoanode of 10 μm shows the highest efficiency up to 0.1141 %, while those with other thicknesses respectively gives 0.0378%, and 0,0283%, revealing the efficiency becomes lower with the increasing thickness of TiO2.
关键词： Titanium Dioxide,Chlorophyll,dye,Resistance
更新于2025-09-16 10:30:52
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Temperature dependence of the parameters of laser-induced fluorescence and species composition of phytoplankton: The theory and the experiments
摘要： The article discusses the opportunity to determine the species composition of a mixture of microalgae by using the temperature dependence of their laser-induced fluorescence (LIF). Experimental temperature dependences of fluorescence were obtained for the following microalgae: Picochlorum maculatum, Dunaliella salina, Chlorella minutissima, Tetraselmis viridis, Porphyridium purpureum, and Rhodomonas salina. It has been shown that the temperature dependence of fluorescence intensity of chlorophyll a in microalgae is reflective of the specific processes in cells of different microalgae species. A mathematical model for the temperature dependence of microalgae fluorescence and its relationship with the processes occurring in microalgae cells when heated has been formulated. The model allows determining the composition of mixtures with sufficient accuracy, as was shown experimentally on test mixtures of microalgae cultures.
关键词： Temperature dependence of fluorescence intensity,Phytoplankton,Chlorophyll a,Laser-induced fluorescence
更新于2025-09-16 10:30:52
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High throughput procedure utilising chlorophyll fluorescence imaging to phenotype dynamic photosynthesis and photoprotection in leaves under controlled gaseous conditions
摘要： Background: As yields of major crops such as wheat (T. aestivum) have begun to plateau in recent years, there is growing pressure to efficiently phenotype large populations for traits associated with genetic advancement in yield. Photosynthesis encompasses a range of steady state and dynamic traits that are key targets for raising Radiation Use Efficiency (RUE), biomass production and grain yield in crops. Traditional methodologies to assess the full range of responses of photosynthesis, such a leaf gas exchange, are slow and limited to one leaf (or part of a leaf ) per instrument. Due to constraints imposed by time, equipment and plant size, photosynthetic data is often collected at one or two phenological stages and in response to limited environmental conditions. Results: Here we describe a high throughput procedure utilising chlorophyll fluorescence imaging to phenotype dynamic photosynthesis and photoprotection in excised leaves under controlled gaseous conditions. When measured throughout the day, no significant differences (P > 0.081) were observed between the responses of excised and intact leaves. Using excised leaves, the response of three cultivars of T. aestivum to a user—defined dynamic lighting regime was examined. Cultivar specific differences were observed for maximum PSII efficiency (Fv′/Fm′—P < 0.01) and PSII operating efficiency (Fq′/Fm′—P < 0.04) under both low and high light. In addition, the rate of induction and relaxation of non-photochemical quenching (NPQ) was also cultivar specific. A specialised imaging chamber was designed and built in-house to maintain gaseous conditions around excised leaf sections. The purpose of this is to manipulate electron sinks such as photorespiration. The stability of carbon dioxide (CO2) and oxygen (O2) was monitored inside the chambers and found to be within ± 4.5% and ± 1% of the mean respectively. To test the chamber, T. aestivum ‘Pavon76’ leaf sections were measured under at 20 and 200 mmol mol?1 O2 and ambient [CO2] during a light response curve. The Fv′/Fm′was significantly higher (P < 0.05) under low [O2] for the majority of light intensities while values of NPQ and the proportion of open PSII reaction centers (qP) were significantly lower under > 130 μmol m?2 s?1 PPFD. Conclusions: Here we demonstrate the development of a high-throughput (> 500 samples day?1) method for phenotyping photosynthetic and photo-protective parameters in a dynamic light environment. The technique exploits chlorophyll fluorescence imaging in a specifically designed chamber, enabling controlled gaseous environment around leaf sections. In addition, we have demonstrated that leaf sections do not different from intact plant material even > 3 h after sampling, thus enabling transportation of material of interest from the field to this laboratory based platform. The methodologies described here allow rapid, custom screening of field material for variation in photosynthetic processes.
关键词： Dynamic,Imaging,Phenotyping,Wheat,Photo-protection,Photosynthesis,Chlorophyll fluorescence
更新于2025-09-16 10:30:52
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ZnO and TiO2 Nanostructured Dye sensitized Solar Photovoltaic Cell
摘要： The performance of nanostructured metal oxides (ZnO and TiO2) based dye sensitized solar cells (DSSC) were investigated. Natural dye, chlorophyll extracted from fresh spinach leaves, was used as sensitizer for fabrication of the cells. ZnO was synthesized by chemical bath deposition technique.The Field emission scanning electron microscopic (FESEM) images show hexagonal patterned ZnO nano-towers of 5 μm length and ~ 1 μm diameter. TiO2 was synthesized by sol-gel method.The FESEM images show that the TiO2 nano-rods of 2 μm length and ~ 300 nm diameter.TiO2 based DSSC was possessed better efficiency of 0.27% as compare to ZnO based DSSC of 0.13%.
关键词： Diffused Reflectance Spectra,Chlorophyll dye,Dye sensitized solar cells,Chemical and sol-gel synthesis
更新于2025-09-16 10:30:52
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[IEEE IECON 2019 - 45th Annual Conference of the IEEE Industrial Electronics Society - Lisbon, Portugal (2019.10.14-2019.10.17)] IECON 2019 - 45th Annual Conference of the IEEE Industrial Electronics Society - Analysis and Characterization of Factors Influencing the Energy Performance of Photovoltaic Systems
摘要： Satellite remote-sensing data and glider data are used to study the Kuroshio meander and surface properties, east of Taiwan. The Kuroshio meandered eastward 13 times between 1993 and 2013 because of cold eddies propagating from the western Pacific. The maximum duration of the meanders was 80 days. The farthest eastward shift of the Kuroshio axis was approximately 270 km from its original position, depending on the size of the cold eddy. Cold eddies reduce the current speed at the Kuroshio axis to 84% of its seasonal average, which is approximately 0.75 m/s. According to glider data, isopycnal uplifting is produced when cold eddies impinge on the Kuroshio, and satellite observations show that the sea surface temperature (SST) drops 1?3 ?C and that the chlorophyll-a (chl-a) concentration increases up to 0.54 mg/m3.
关键词： cold eddy,sea surface temperature (SST),Chlorophyll-a (chl-a),kuroshio meander
更新于2025-09-16 10:30:52
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Investigation of Cell Growth and Chlorophyll a Content of the Coccolithophorid Alga Emiliania huxleyi by Using Simple Bench-Top Flow Cytometry
摘要： The coccolithophorid alga Emiliania huxleyi produces micro-structured calcite particles, which are called coccoliths. Due to their unique and sophisticated structure, coccoliths are highly promising for different industrial applications, such as paper manufacturing, color and lacquer preparation. The mass production of coccoliths requires the evaluation of optimum cultivation conditions. This study investigates the impact of varying irradiance (10-1500 μmol m-2 s-1) on growth and chlorophyll a content of two calcifying strains CCMP371 and RCC1216 as well as on the non-calcifying strain RCC1217 (haploid form of RCC1217). The light kinetics contradicts the popular opinion, that E. huxleyi is an extraordinarily light tolerating alga in general. Photoinhibition was already observed at irradiance >500 μmol m-2 s-1 in the case of the calcifying strains. Furthermore, light requirements to grow at maximum growth rate, as well as thresholds towards photoinhibition were considerably different between calcifying and non-calcifying strains. The haplont required significantly higher irradiance to reach maximum μspec (>200 μmol m-2 s-1), while being much more tolerant to towards photoinhibition, which occurred not until 800 μmol m-2 s-1. Furthermore, a novel method was proposed to allow for the estimation of chlorophyll a content from flow cytometry data. By comprising an Advanced Fluorescence Ratio (AFLR), which considers culture heterogeneity, this method enables for simple chlorophyll a estimation also in older cultures of calcifying Emiliania huxleyi, which tend to build agglomerates.
关键词： Autofluorescence,characterization,Photosynthetic pigments,Flow cytometry,Chlorophyll,Microalgae
更新于2025-09-16 10:30:52
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AIP Conference Proceedings [AIP Publishing INTERNATIONAL CONFERENCE ON SCIENCE AND APPLIED SCIENCE (ICSAS) 2019 - Surakarta, Indonesia (20 July 2019)] INTERNATIONAL CONFERENCE ON SCIENCE AND APPLIED SCIENCE (ICSAS) 2019 - Effect concentration of dye solution binahong leaves to the efficiency of dye-sensitized solar cell (DSSC)
摘要： Variations concentration dye solution to the performance of Dye-Sensitized Solar Cell (DSSC) has been conducted. The natural dyes used in this research was extracted from binahong leaves chlorophyll. The structure of DSSC consists of TiO2 as a working electrode, chlorophyll as a photosensitizer, I/I3- as an electrolyte, and platinum as the counter electrode. The fabrication of working electrode used spin coating methods. Dye with four variations concentrations were carried out, namely 1gr/100mL, 3gr/100mL, 5gr/100mL, and 7gr/100mL. The optical characterization to investigation the absorbance of pure dye and dye immersed on to TiO2 using UV-Vis spectrophotometer. Then, current-voltage (I-V) characteristic DSSC were measured using Keithley I-V Meter. The absorbance peak of dye increases with increasing dye concentration. Maximum absorbance of layer TiO2 and highest efficiency value contained at concentration dye solution of 5gr/100mL is 0.0662%.
关键词： binahong leaves,TiO2,chlorophyll,Dye-Sensitized Solar Cell,efficiency
更新于2025-09-12 10:27:22
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Theoretical study on the effect of solvents in chlorophyll solution for Dye-Sensitized Solar Cell
摘要： Using the density functional theory (DFT) and time-dependent DFT (TD-DFT), we have theoretically studied the electron excitation and absorption spectra of chlorophyll solution with several solvents for Dye-Sensitized Solar Cell (DSSC) application. The solvents were aceton, acetonitrile, DMSO, ethanol, hexane, methanol, THF and water. Also, energy level, oscilator strength, light harvesting efficiency and electron injection have been investigated. The studied dye in the presence of the solvents showed a smaller gap of the highest occupied molecular orbital (HOMO) - the lowest unoccupied molecular orbital (LUMO) and a higher light harvesting, oscillator strength and red shift in the absorption spectra. These changes facilitate the charge transfer phenomena in the nano structure of the chlorophyll as dye and improve the solar cell efficiency.
关键词： chlorophyll,DFT,TD-DFT,solvents,Dye-Sensitized Solar Cell
更新于2025-09-12 10:27:22