scholarly journals Interdependence between oscillations and transients of delayed fluorescence induction processes in the thylakoid membrane of the intact maize leaf: Responses to effects of increased temperatures and drought

2010 ◽  
pp. 7-26
Author(s):  
Cedomir Radenovic ◽  
Ksenija Markovic ◽  
Aleksandar Radojcic ◽  
Violeta Andjelkovic ◽  
Aleksandar Kalauzi
Keyword(s):  
White Light ◽  
Thylakoid Membrane ◽  
Delayed Fluorescence ◽  
Fluorescence Induction ◽  
Leaf Segment ◽  
Critical Temperatures ◽  
Intact Leaf ◽  
Maize Inbreds ◽  
Chemical Character ◽  
Generation Mechanisms

Standard induction processes of delayed fluorescence (DF) of chlorophyll (induction signals) occur when an intact leaf segment of maize inbreds and hybrids is kept in the phosphoroscope darkroom for more than 15 minutes (t > 15 min), and at the same time the leaf is illuminated with the intermittent white light. Resolved induction processes of DF chlorophyll into transients: A, B, C, D and E occur when the intact leaf segment of maize inbreds and hybrids is kept in the phosphoroscope darkroom for a significantly shorter period (500 s > t > 30 s), with the time rate t of 30 s, prior to its illumination with the intermittent white light. Induction transients: A, B, C, D and E are characterized with the time of their generation: tA = 31?6 ms (A), tB = 5 ? 0,5 s (B), tC = 15?5 s (C), tD = 360?20 s (D) and tE = 670?35 s (E), dynamics of changes in transients intensities (IA, IB, IC, ID and IE) and mechanisms of their generation. The induction processes of chlorophyll DF of the intact leaf of maize inbreds and hybrids resolved into transients: A, B, C, D and E are accompanied by the occurrence and different levels of activation energy (Ea, kJ mol-1) that correspond to critical temperatures ranging from 28 to 33?C. The generation mechanisms of induction transients A, B, C, D and E classify them into two groups. Transients A and B are of a physical character, while the transients: C, D, and E are of a chemical character. It is shown that the generation of the induction transients: B, C, D and E simultaneously follows establishing of the oscillations of induction processes of the DF chlorophyll. Oscillating of induction processes of DF chlorophyll is explained by the ion (K+, Na+, H+, Cl-) transport mechanism across the thylakoid membrane of the intact leaf of maize inbreds and hybrids grown under conditions of air drought, increased temperatures and water deficiency in the medium.

scholarly journals Dynamics of generating transients of delayed fluorescence induction signal and photosynthetic antennas: A possible relationship: Mathematical modeling approach

2007 ◽  
pp. 5-26 ◽  
Author(s):  
Cedomir Radenovic ◽  
Aleksandar Kalauzi ◽  
Kosana Konstantinov ◽  
Goran Drinic
Keyword(s):  
Photosynthetic Apparatus ◽  
Delayed Fluorescence ◽  
Fluorescence Induction ◽  
Photon Absorption ◽  
Leaf Segment ◽  
Model Parameters ◽  
Time Model ◽  
Intermittent Light ◽  
Induction Signal ◽  
Photosynthetic Antennas

A mathematical model was developed for resolved temporal transients of experimentally recorded delayed fluorescence (DF) induction signal. During an intermittent light regime, antennas of the photosynthetic apparatus were treated as targets, repeatedly hit by potentially absorbable photons within a series of consecutive light flashes. Formulas were derived for the number of antennas, cumulatively hit by a specific number of photons, as function of the flash serial number (time). Model parameters included: number of absorbable photons in one flash, antenna sizes and numbers. A series of induction curves were analyzed, obtained from a ZeamaysL. leaf segment and differing in the previous dark period (td). Each curve, consisting of the two most prominent DF transients (C and D), was fitted with several model types, differing in the number of absorbed photons. For both transients, the best fitting result was achieved when DF induction was linked to the second absorbed photon. As expected, model parameters related to antenna sizes showed weaker dependence on td than those referring to antenna numbers. With restrictions applied in this model, the two DF induction transients may be related to two classes of photosynthetic antennas. Their different sizes may have a predominant influence on the efficiency of photon absorption, and possibly time-dependent appearance of DF transients.

scholarly journals White light emitting diode based on purely organic fluorescent to modern thermally activated delayed fluorescence (TADF) and perovskite materials

2019 ◽  
Vol 6 (1) ◽  
Author(s):  
Dipjyoti Das ◽  
Peddaboodi Gopikrishna ◽  
Debasish Barman ◽  
Ramesh Babu Yathirajula ◽  
Parameswar Krishnan Iyer
Keyword(s):  
White Light ◽  
Light Emitting Diode ◽  
Solution Process ◽  
Delayed Fluorescence ◽  
Organic Polymer ◽  
Modern Concept ◽  
Thermally Activated Delayed Fluorescence ◽  
Light Emitting ◽  
Thermally Activated ◽  
Synthesis Strategy

Abstract White organic/polymer light emitting diode (WOLED/WPLED) processed from solution has attracted significant research interest in recent years due to their low device production cost, device flexibility, easy fabrication over large area including roll to roll and ability to print in various designs and shapes providing enormous design possibilities. Although WOLEDs fabricated using solution process lack their thermally evaporated counterparts in terms of device efficiency, remarkable progress has been made in this regard in recent years by utilizing new materials and device structures. In the present review, we have summarized and extrapolated an excellent association of old and modern concept of cost-effective materials and device structure for realization of white light. In particular, this article demonstrated and focused on design, and development of novel synthesis strategy, mechanistic insights and device engineering for solution process low cost WOLEDs device. Herein, an overview of the prevailing routes towards white light emitting devices (WLEDs) and corresponding materials used, including polymer based WLED, small molecules emitters based thermally activated delayed fluorescence (TADF), perovskite light-emitting diodes (PeLEDs) and hybrid materials based LEDs, color down-converting coatings with corresponding best efficiencies ever realized. We presume that this exhaustive review on WLEDs will offer a broad overview of the latest developments on white SSL and stonework the approach en route for innovations in the immediate future.

The Inhibition of Photosynthetic Electron Transport by DBMIB and its Restoration by p-Phenylenediamines; Studied by Means of Prompt and Delayed Chlorophyll Fluorescence of Green Algae

1974 ◽  
Vol 29 (11-12) ◽  
pp. 725-732 ◽  
Author(s):  
Robert Bauer ◽  
Mathijs J. G. Wijnands
Keyword(s):  
Chlorophyll Fluorescence ◽  
Electron Transport ◽  
Photosystem Ii ◽  
Photosynthetic Electron Transport ◽  
Primary Electron ◽  
Delayed Fluorescence ◽  
Fluorescence Induction ◽  
Chlorophyll Fluorescence Induction ◽  
Exchange Reactions ◽  
Redox Systems

Abstract The effect of the plastohydroquinone antagonist dibromothym oquinone (DBMIB) on photosynthetic electron transport reactions was studied in the presence and absence of p-phenylene-diamines by means of measurements of prompt and delayed chlorophyll fluorescence induction of the green alga Scenedesm us obliquus. Prompt and delayed chlorophyll fluorescence induction phenomena are valid indicators for the native presence of and cooperation between the two photosynthetic light reactions. Their kinetics reflect the balancing of electron exchange reactions in the chain of coupled redox-systems between the two photosystems upon sudden illumination. From distinct alterations of the short-term (sec) light induced changes in the yield of prom pt and delayed chlorophyll fluorescence it is concluded that DBMIB inhibits the photosynthetic electron transport in the chain of redox-systems between the two light reactions. There is evidence to show that upon illumination of DBMIB treated cells only the reduction of primary electron ac­ceptor pools of photosystem II (i. e. Q and PQ) is still possible. After their reduction the further electron transport through photosystem II is blocked. The addition of p-phenylenediamines to DBM IB-treated cells abolishes the typical DBMIB-affected prom pt and delayed fluorescence inhibition curves and the normal induction curves re­ appear qualitatively in all their important features. From these measurements it is suggested that the redox properties of p-phenylenediamines allow an electron transport bypass of the DBMIB inhibition site which results in a fully restored photosynthetic electron transport from water to NADP.

White Light Afterglow in Carbon Dots Achieved via Synergy between the Room‐Temperature Phosphorescence and the Delayed Fluorescence

Small ◽  
2021 ◽  
pp. 2105415
Author(s):  
Jinyang Zhu ◽  
Junhua Hu ◽  
Qiang Hu ◽  
Xiaoyu Zhang ◽  
Elena V. Ushakova ◽  
...  
Keyword(s):  
White Light ◽  
Carbon Dots ◽  
Room Temperature ◽  
Delayed Fluorescence ◽  
Room Temperature Phosphorescence
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