Analyzing the Distribution of Decay Constants in Pulse Fluorimetry Using the Maximum Entropy Method

Brochon, J. C.; Livesey, A. K.

doi:10.1007/978-1-4684-5619-6_23

Cited by 3 publications

(4 citation statements)

References 17 publications

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“…A quadruple exponential model reduces the 2 value significantly (Table I). Analysis of the decay by MEM (Brochon & Livesey, 1988;Livesey & Brochon, 1987), using the above-described stopping criterion, seems to credit the existence of four classes of lifetimes centered around 0.2, 1, 3, and 5 ns for the total fluorescence intensity decays culminating at 500000 counts (Figure 5C). As in the simulations involving four discrete exponentials, not enough information is contained in the less cumulated curves (Figure 5A).…”

Section: Resultsmentioning

confidence: 91%

“…The total intensity decay data were analyzed by nonlinear least-squares regression and by the maximum en-1 Abbreviations: MEM, maximum entropy method; Apo c, horse heart apocytochrome c; NMR, nuclear magnetic resonance. tropy method developed recently for fluorescence spectroscopy (Brochón & Livesey, 1988;. The analysis of the total fluorescence intensity decays suggests the existence of discrete interconvertible environments for the Trp-59.…”

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confidence: 99%

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Nanosecond dynamics of horse heart apocytochrome c in aqueous solution as studied by time-resolved fluorescence of the single tryptophan residue (Trp-59)

Vincent

Brochon²,

Mérola³

et al. 1988

Biochemistry

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The time-resolved fluorescence emission characteristics of the single tryptophan residue (Trp-59) of horse heart apocytochrome c--the precursor of the intramitochondrial cytochrome c--were studied in aqueous solution. The total fluorescence intensity decay measured over the whole emission spectrum was analyzed as a sum of three or four exponentials by the nonlinear least-squares method, the last model always providing a slight but significant decrease in the chi 2 values. Maximum entropy analysis, recently developed for time-resolved fluorometry (Livesey et al., 1987; Livesey & Brochon, 1987), strongly suggests the existence of a distribution including at least four separate classes of lifetimes. The center values were around 0.1-0.2, 1, 3, and 5 ns, in agreement with the lifetime values obtained by nonlinear least-squares regression analysis. As a function of the emission wavelength, these values remained constant within the experimental error, whereas a redistribution of the fractional amplitudes was observed: the contributions of the short components increased in the blue edge region of the emission spectrum. Temperature increase led essentially to a redistribution of the fractional amplitudes, affecting mostly that of the 5-ns component, which almost totally disappeared at high temperature (35-40 degrees C). The lifetime values were not significantly affected except for the 3-ns component, which decreased by about 15% in the temperature range studied. Such observations strongly suggest that the protein exists under different conformational substates in thermal equilibrium. Time-resolved fluorescence anisotropy measurements evidenced the existence of fast internal rotation of the Trp residue. An average maximum restricted angle of rotation of around 55 degrees was calculated. A second internal motion, slower by 1 order of magnitude, corresponding likely to a local motion of the peptide chain involving the Trp-59 residue, was detected on the anisotropy decay curve. Finally, the longest correlation time (5 ns) should correspond to the average rotation of the overall protein. Its value doubled as a function of the protein concentration, revealing an association process leading most likely to a dimer in the concentration range studied (2-139 microM). The flexibility of the peptide chain was more restrained in the associated than in the monomeric form, but the fast internal rotation of the Trp residue was not.

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Section: Resultsmentioning

confidence: 91%

mentioning

confidence: 99%

Nanosecond dynamics of horse heart apocytochrome c in aqueous solution as studied by time-resolved fluorescence of the single tryptophan residue (Trp-59)

Vincent

Brochon²,

Mérola³

et al. 1988

Biochemistry

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“…However, the relationship is just opposite for the cost index. Detailed discussions and procedures are available in the references (Livesey et al, 1987;Swaminathan and Periasamy, 1996;Sun et al, 2012b).…”

Section: Methodology 231 Entropy Methodsmentioning

confidence: 99%

Non-coordination in China’s urbanization: Assessment and affecting factors

et al. 2013

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Urbanization is a comprehensive concept, a trinity process that is based on the interactions and mutual influences among the population urbanization, economic urbanization and space urbanization, in which, people are the central and leading players in this process, while economic activities serve as the driving force and space is the carrier-the physical or material setting as well as the product. So the coordination among these processes is crucial for a country or region′s sustainable development. China is experiencing rapid growth of cities and a surge in urban population, with the basic national condition of many people and little land, which calls for a systematic study of the issue of coordinated urbanization from theoretical, methodological and practical perspectives. Based on the concept of urbanization and non-coordination of urbanization, this article built a quantitative method to identify and evaluate the urbanization and non-coordination of urbanization, and made an empirical analysis in China between 2000 and 2008. The results show that the non-coordination overall level of China′s urbanization declined during the study period, because population urbanization, economic urbanization, and space urbanization exhibited different trajectories of change. This study also reveals that performance assessment system, household registration system, and urban land expropriation system, etc., are the main affecting factors. At the end, we put forward some suggestions to achieve sustainable development of China′s urbanization from the aspects of improving the local government′s objective function, implementing the urban planning system, enforcing public participation aspects and so on.

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“…The emission from all maxima has been investigated in the time domain by means of TRPL. Then, recorded PL decays were analyzed employing the PTI FelixGX software by Photon Technology International that utilizes the maximal entropy method (MEM) 48,49 , which among many applications has proved effective in multi-exponential luminescence decay reconstruction 50,51 . It allows one to extract photoluminescence lifetimes without initial knowledge on the number of underlying processes, and thus decay components.…”

Section: Photoluminescence Dynamicsmentioning

confidence: 99%

Optical and electronic properties of low-density InAs/InP quantum dot-like structures devoted to single-photon emitters at telecom wavelengths

Holewa,

Gawełczyk,

Ciostek

et al. 2019

Preprint

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Due to their band-structure and optical properties, InAs/InP quantum dots (QDs) constitute a promising system for single-photon generation at third telecom window of silica fibers and for applications in quantum communication networks. However, obtaining the necessary low in-plane density of emitters remains a challenge. Such structures are also still less explored than their InAs/GaAs counterparts regarding optical properties of confined carriers. Here, we report on the growth via metal-organic vapor phase epitaxy and investigation of low-density InAs/InP QD-like structures, emitting in the range of 1.2-1.7 µm, which includes the S, C, and L bands of the third optical window. We observe multiple photoluminescence (PL) peaks originating from flat QDs with height of small integer numbers of material monolayers. Temperature-dependent PL reveals redistribution of carriers between families of QDs. Via time-resolved PL, we obtain radiative lifetimes nearly independent of emission energy in contrast to previous reports on InAs/InP QDs, which we attribute to strongly height-dependent electron-hole correlations. Additionally, we observe neutral and charged exciton emission from spatially isolated emitters. Using the 8-band k•p model and configuration-interaction method, we successfully reproduce energies of emission lines, the dispersion of exciton lifetimes, carrier activation energies, as well as the biexciton binding energy, which allows for a detailed and comprehensive analysis of the underlying physics.

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Analyzing the Distribution of Decay Constants in Pulse Fluorimetry Using the Maximum Entropy Method

Cited by 3 publications

References 17 publications

Nanosecond dynamics of horse heart apocytochrome c in aqueous solution as studied by time-resolved fluorescence of the single tryptophan residue (Trp-59)

Nanosecond dynamics of horse heart apocytochrome c in aqueous solution as studied by time-resolved fluorescence of the single tryptophan residue (Trp-59)

Non-coordination in China’s urbanization: Assessment and affecting factors

Optical and electronic properties of low-density InAs/InP quantum dot-like structures devoted to single-photon emitters at telecom wavelengths

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