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Published in Philip A. Laplante, Comprehensive Dictionary of Electrical Engineering, 2018
photorefractive crystal phosphoric acid fuel cell (PAFC) a fuel cell that uses hydrogen as fuel, and phosphoric acid as an electrolyte. It can generate 5 to 250kW of power, and hence can be used in automotive applications. See also akaline fuel cell, proton exchange membrane fuel cell, molten carbonate fuel cell, solid oxide fuel cell. photochemistry chemical reactions that occur as a result of electronically exciting at least one of the reactant molecules with light. photodetector device capable of producing or modifying an electrical signal in proportion to the amount of light falling on the active area of the device. photoelastic effect mechanical strain in a solid causes a change in the index of refraction that can affect the phase of a light wave traveling in the strain medium. photogalvanic effect photolithography See photovoltaic effect. See optical lithography. (2) complex output pulses that are generated when two intense input pulses interact with the same semiclassically described laser medium. photon lifetime See cavity lifetime.
Introduction to Fluorescence and Photophysics
Published in Mary-Ann Mycek, Brian W. Pogue, Handbook of Biomedical Fluorescence, 2003
In photochemistry or photophysics, the quantum yield of any given process is defined as the number of molecules that undergo the process divided by the total number of molecules excited. The quantum yield of fluorescence is therefore defined as follows: () Φf=numberoffluorescencephotonsemittednumberofphotonsabsorbed
Synthesis of LDH for Photocatalytic Removal of Toxic Dyes from Aqueous Solution
Published in Satya Bir Singh, Prabhat Ranjan, A. K. Haghi, Materials Modeling for Macro to Micro/Nano Scale Systems, 2022
Rasna Devi, Dipshikha Bharali, Ramesh Chandra Deka
Apart from natural existence, LDH can be prepared synthetically. Tuning different structural constituents such as M(II)/M(III) ratio, the interlayer gallery anions, activation temperature, and rehydration temperature, LDH can be synthesized with varied morphologies and surface area [25]. This leads to application in various fields such as catalysis, photochemistry, pharmaceuticals, adsorption, electrochemistry, etc. Besides, LDH can be used as host for proper incorporation of selective guest species such as metal oxides, photoactive metals, and enantioselective reagents inside the structure to carry out variety of reactions.
Characterization of macrophytes for Na+ removal in synthetic Na-salt solution batch under greenhouse conditions
Published in International Journal of Phytoremediation, 2021
Rujira Tisarum, Thapanee Samphumphuang, Kwankhao Cha-um, Methee Khamduang, Suriyan Cha-um
Chlorophyll fluorescence emission was measured from the adaxial surface of the second fully expanded leaf (average of four points per plant in each replication) using a fluorescence monitoring system (FMS 2; Hansatech Instruments Ltd., Norfolk, UK) in the pulse amplitude modulation mode (Loggini et al. 1999). A leaf kept in dark for 30 min was initially exposed to the modulated measuring beam of far-red light (LED source) with typical peak at wavelength of 735 nm. Original (F0) and maximum (Fm) fluorescence yields were measured under weak modulated red light (<85 µmol m−2 s−1) with 1.6 s pulses of saturating light (>1500 µmol m−2 s−1 PPFD) and calculated using FMS software for Windows®. The variable fluorescence yield (Fv) was calculated using the equation: Fv=Fm–F0. The ratio of variable to maximum fluorescence (Fv/Fm) was calculated as the maximum quantum yield of PSII photochemistry. The photon yield of PSII (ΦPSII) in the light was calculated as: ΦPSII=(Fm′−F)/Fm′ after 45 s of illumination, when steady state was achieved (Maxwell and Johnson 2000).
Cotyledonary leaves effectively shield the true leaves in Ricinus communis L. from copper toxicity
Published in International Journal of Phytoremediation, 2021
Similar results were also observed in the case of Fv/Fm and PIabs. The Fv/Fm ratio represents the capturing and conversion efficiency of harvested light energy and is used for the assessment of quantum yield of primary photochemistry of PSII, and PIabs indicates the performance index on an absorption basis which is an indicator of plant vitality (Strasser et al. 2004). The reduction of Fv/Fm and PIabs was negligible in true leaves in the presence of cotyledonary leaves, but at the same time, there was a drastic reduction of these parameters in the true leaves in the absence of cotyledonary leaves. The value of Fv/Fm was decreased to 0.715 (0.847 in control) at 200 μΜ CuSO4 in true leaves in the absence of cotyledonary leaves. But the value did not show any significant variation in true leaves from that of control in the presence of cotyledonary leaves. The decline in the Fv/Fm ratio in the cotyledonary leaves of R. communis seedlings (∼100%) suggests that Cu inhibited the quantum efficiency of PSII photochemistry by reducing the rate of primary charge separation and also by the release of some minor antenna complex from PSII (Mathur et al. 2016).
Growth and physiological responses of three poplar clones grown on soils artificially contaminated with heavy metals, diesel fuel, and herbicides
Published in International Journal of Phytoremediation, 2020
Andrej Pilipović, Ronald S. Zalesny, Saša Orlović, Milan Drekić, Saša Pekeč, Marina Katanić, Leopold Poljaković-Pajnik
During August of the first two growing seasons, physiological parameters were measured on fully developed leaves at the seventh Leaf Plastochron Index (i.e., LPI = 7) (Larson and Isebrands 1971) from five trees per clone × treatment interaction per block (i.e., 15 trees were sampled for each subplot). Gas exchange measurements were conducted using an ADC LCPro + Portable Photosynthesis System (ADC Bioscientific, Ltd., Hoddesdon, UK) under controlled, constant light conditions of 1000 μmol m−2 s−1, constant ambient air supply of 100 μmol s−1, and ambient levels of air humidity and temperature. Direct gas exchange parameters included photosynthetic rate (A) (μmol m−2 s−1 CO2), transpiration rate (E) (mmol m−2 s−2 H2O), substomatal CO2 concentration (Ci) (vpm), and stomatal conductance (gs) (mol m−2 s−1). Instantaneous WUE (μmol O2 mmol H2O−1) was computed as the ratio of A/E (Farquhar et al.1989). In addition to these gas exchange parameters, in the first growing season, the leaves were dark-adapted for 30 min and chlorophyll A fluorescence was measured on the middle section of leaf blades using an OS1-FL portable fluorometer (Opti Sciences OS1-FL, Hudson, NH) (Öquist and Wass 1988). During measurement, the maximum quantum efficiency of PSII photochemistry or maximum quantum yield of PSII (Fv/Fm) was recorded.