When exposed to excess light illumination photosynthetic organisms switch into a photoprotective quenched state where the excess energy is safely dissipated as heat. When these processes are investigated by means of ultrafast spectroscopy, the experimentalist is faced with the unnatural process of singlet–singlet annihilation which often makes the interpretation of the results very complicated....

The light-harvesting antenna of photosystem II (PSII) has the ability to switch rapidly between a state of efficient light use and one in which excess excitation energy is harmlessly dissipated as heat, a process known as qE. We investigated the single-molecule fluorescence intermittency of the main component of the PSII antenna (LHCII) under conditions that mimic efficient use of light or qE, ...

Single-molecule spectroscopy was employed to elucidate the fluorescence spectral heterogeneity and dynamics of individual, immobilized trimeric complexes of the main light-harvesting complex of plants in solution near room temperature. Rapid reversible spectral shifts between various emitting states, each of which was quasi-stable for seconds to tens of seconds, were observed for a fraction of ...

The main purpose of this study is measuring and comparing of peanut harvesting loss in manual and mechanical methods in addition to economic analysis of them. Hence, a field was selected in Astaneh-Ashrafiyeh and divided to three different plots. Two plots were applied to measure mechanical harvesting loss and third one was applied for manual harvesting loss. According to test results, the lowe...

We study the problem on optimal harvesting from a population in a stochastic crowded environment with harvesting cost. In this problem, the size of the population satisfy the stochastic logistic differential equation, which serves as a model for population growth in a stochastic environment with finite carrying capacity when harvesting is exercised. We consider the following problem: What harve...

Photosynthetic organisms harvest sunlight with near unity quantum efficiency. The complexity of the electronic structure and energy transfer pathways within networks of photosynthetic pigment-protein complexes often obscures the mechanisms behind the efficient light-absorption-to-charge conversion process. Recent experiments, particularly using two-dimensional spectroscopy, have detected long-l...

The biosynthetic pathway of lutein, the most abundant carotenoid in leaves, has been extensively studied, while its degradation pathway during senescence is poorly understood. We found that a novel carotenoid derivative, lutein 3-acetate, accumulates in senescent leaves of rice (Oryza sativa L.). The change in contents of lutein and lutein 3-acetate suggests that lutein is converted to lutein 3...

Protection against strong-light-induced photodamage of the photosynthetic apparatus and entire organisms is a vital activity in plants and is also realized at the molecular level of the antenna complexes. Reported recently, the regulatory mechanisms which operate in the largest plant antenna complex, LHCII (light-harvesting complex II), based on light-driven processes, are briefly reviewed and ...

Electrostatic couplings between chromophores in photosynthetic pigment-protein complexes, and interactions of pigments with the surrounding protein environment, produce a complicated energy landscape of delocalized excited states. The resultant electronic structure absorbs light and gives rise to energy transfer steps that direct the excitation toward a site of charge separation with near unity...

We obtain solutions of M coupled nonlinear Schrodinger equations that describe multisoliton complexes (MCs) on a background. We present explicit multiparameter families of solutions and numerical simulations, demonstrating specific features of MCs and their collisions. It is shown, in particular, that a MC on a background can have a complicated intensity profile due to a nonlinear superposition...