Melo, Thor Bernt

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  • Melo, Thor Bernt (3)
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Author's Bibliography

Using optical fibers to measure absorption in intact conifer leaves, relative numbers of chloroplasts, and pigment content

Radotić, Ksenija; Melo, Thor Bernt

(Springer, Dordrecht, 2020)

TY  - JOUR
AU  - Radotić, Ksenija
AU  - Melo, Thor Bernt
PY  - 2020
UR  - http://rimsi.imsi.bg.ac.rs/handle/123456789/1298
AB  - For investigations of ongoing processes in plants, such as photosynthesis in conifer leaves, nondestructive and noninvasive measuring techniques are needed. In this paper, a novel approach has been developed for the measurement of chloroplasts' numbers and pigment contents in conifer leaves based on the measurements of leaf absorption spectra using optical fibers and an array spectrophotometer. To eliminate the effect of scattering on the measured absorption spectra, a strategy has been applied taking advantage of the combined use of thin optical fibers normal to the needle's longitudinal axis and the phenomenon that scattering is largest in the forward direction. The optical path in the leaf is nearly the distance between the fiber tips; thus, we were able to obtain the absorption spectrum of the pigments in situ. A effect of the measured absorption spectra, occurring due to the organization of pigments in the leaf and interaction between light and leaf interior, can be accounted for by using the so-called Duysens transformation. Using this transformation, pigment contents and the relative number of chloroplasts can be obtained from the measured absorption spectra. We applied the method to observe pigment concentrations in different stages of the greening process in the leaves of two conifer species, Taxus baccata and Picea abies. The presented method may be used to estimate changes in chloroplast number and pigment content during various phases of greening of a species and to observe differences among various species.
PB  - Springer, Dordrecht
T2  - Journal of Biological Physics
T1  - Using optical fibers to measure absorption in intact conifer leaves, relative numbers of chloroplasts, and pigment content
EP  - 43
IS  - 1
SP  - 33
VL  - 46
DO  - 10.1007/s10867-020-09539-4
ER  - 
@article{
author = "Radotić, Ksenija and Melo, Thor Bernt",
year = "2020",
abstract = "For investigations of ongoing processes in plants, such as photosynthesis in conifer leaves, nondestructive and noninvasive measuring techniques are needed. In this paper, a novel approach has been developed for the measurement of chloroplasts' numbers and pigment contents in conifer leaves based on the measurements of leaf absorption spectra using optical fibers and an array spectrophotometer. To eliminate the effect of scattering on the measured absorption spectra, a strategy has been applied taking advantage of the combined use of thin optical fibers normal to the needle's longitudinal axis and the phenomenon that scattering is largest in the forward direction. The optical path in the leaf is nearly the distance between the fiber tips; thus, we were able to obtain the absorption spectrum of the pigments in situ. A effect of the measured absorption spectra, occurring due to the organization of pigments in the leaf and interaction between light and leaf interior, can be accounted for by using the so-called Duysens transformation. Using this transformation, pigment contents and the relative number of chloroplasts can be obtained from the measured absorption spectra. We applied the method to observe pigment concentrations in different stages of the greening process in the leaves of two conifer species, Taxus baccata and Picea abies. The presented method may be used to estimate changes in chloroplast number and pigment content during various phases of greening of a species and to observe differences among various species.",
publisher = "Springer, Dordrecht",
journal = "Journal of Biological Physics",
title = "Using optical fibers to measure absorption in intact conifer leaves, relative numbers of chloroplasts, and pigment content",
pages = "43-33",
number = "1",
volume = "46",
doi = "10.1007/s10867-020-09539-4"
}
Radotić, K.,& Melo, T. B.. (2020). Using optical fibers to measure absorption in intact conifer leaves, relative numbers of chloroplasts, and pigment content. in Journal of Biological Physics
Springer, Dordrecht., 46(1), 33-43.
https://doi.org/10.1007/s10867-020-09539-4
Radotić K, Melo TB. Using optical fibers to measure absorption in intact conifer leaves, relative numbers of chloroplasts, and pigment content. in Journal of Biological Physics. 2020;46(1):33-43.
doi:10.1007/s10867-020-09539-4 .
Radotić, Ksenija, Melo, Thor Bernt, "Using optical fibers to measure absorption in intact conifer leaves, relative numbers of chloroplasts, and pigment content" in Journal of Biological Physics, 46, no. 1 (2020):33-43,
https://doi.org/10.1007/s10867-020-09539-4 . .
1
1
1

Fluorescence and phosphorescence of tryptophan in peptides of different length and sequence

Radotić, Ksenija; Melo, Thor Bernt; Leblanc, Roger M.; Yousef, Yaser A.; Naqvi, K. Razi

(Elsevier Science Sa, Lausanne, 2016)

TY  - JOUR
AU  - Radotić, Ksenija
AU  - Melo, Thor Bernt
AU  - Leblanc, Roger M.
AU  - Yousef, Yaser A.
AU  - Naqvi, K. Razi
PY  - 2016
UR  - http://rimsi.imsi.bg.ac.rs/handle/123456789/988
AB  - To interpret accurately protein fluorescence and phosphorescence, it is essential to achieve a better understanding of the luminescence properties of tryptophan (Trp, or W) in peptides. In published literature data on luminescence of peptides of varied length are scarce. This article describes studies of fluorescence and phosphorescence properties of the eight Trp-containing synthetic peptides: WAK, AWK, SWA, KYLWE, AVSWK, WVSWAK, WAKLAWE, and AVSWAKLARE. The aim was to investigate which factors influence the fluorescence yield and phosphorescence-spectra and lifetimes. Absorption spectra, room temperature fluorescence emission and corresponding excitation spectra and time-resolved phosphorescence spectra (77 K) have been recorded; the dependence of the fluorescence quantum yield on the specific peptide and its variation with the wavelength of excitation has been studied. The changes in fluorescence yield and shape of phosphorescence spectra are explained in terms of intemal electron and proton transfer. The structured phosphorescence spectrum originates from proton transfer occurring upon excitation of Trp, while electron transfer gives rise to a non-structured luminescence spectrum. There is also electron transfer from higher vibronic S-1 states. In the peptides there is higher probability of electron transfer than in Trp alone. The obtained data are interpreted in light of the peptides' sequence, length and conformation.
PB  - Elsevier Science Sa, Lausanne
T2  - Journal of Photochemistry and Photobiology B-Biology
T1  - Fluorescence and phosphorescence of tryptophan in peptides of different length and sequence
EP  - 128
SP  - 120
VL  - 157
DO  - 10.1016/j.jphotobiol.2016.02.011
ER  - 
@article{
author = "Radotić, Ksenija and Melo, Thor Bernt and Leblanc, Roger M. and Yousef, Yaser A. and Naqvi, K. Razi",
year = "2016",
abstract = "To interpret accurately protein fluorescence and phosphorescence, it is essential to achieve a better understanding of the luminescence properties of tryptophan (Trp, or W) in peptides. In published literature data on luminescence of peptides of varied length are scarce. This article describes studies of fluorescence and phosphorescence properties of the eight Trp-containing synthetic peptides: WAK, AWK, SWA, KYLWE, AVSWK, WVSWAK, WAKLAWE, and AVSWAKLARE. The aim was to investigate which factors influence the fluorescence yield and phosphorescence-spectra and lifetimes. Absorption spectra, room temperature fluorescence emission and corresponding excitation spectra and time-resolved phosphorescence spectra (77 K) have been recorded; the dependence of the fluorescence quantum yield on the specific peptide and its variation with the wavelength of excitation has been studied. The changes in fluorescence yield and shape of phosphorescence spectra are explained in terms of intemal electron and proton transfer. The structured phosphorescence spectrum originates from proton transfer occurring upon excitation of Trp, while electron transfer gives rise to a non-structured luminescence spectrum. There is also electron transfer from higher vibronic S-1 states. In the peptides there is higher probability of electron transfer than in Trp alone. The obtained data are interpreted in light of the peptides' sequence, length and conformation.",
publisher = "Elsevier Science Sa, Lausanne",
journal = "Journal of Photochemistry and Photobiology B-Biology",
title = "Fluorescence and phosphorescence of tryptophan in peptides of different length and sequence",
pages = "128-120",
volume = "157",
doi = "10.1016/j.jphotobiol.2016.02.011"
}
Radotić, K., Melo, T. B., Leblanc, R. M., Yousef, Y. A.,& Naqvi, K. R.. (2016). Fluorescence and phosphorescence of tryptophan in peptides of different length and sequence. in Journal of Photochemistry and Photobiology B-Biology
Elsevier Science Sa, Lausanne., 157, 120-128.
https://doi.org/10.1016/j.jphotobiol.2016.02.011
Radotić K, Melo TB, Leblanc RM, Yousef YA, Naqvi KR. Fluorescence and phosphorescence of tryptophan in peptides of different length and sequence. in Journal of Photochemistry and Photobiology B-Biology. 2016;157:120-128.
doi:10.1016/j.jphotobiol.2016.02.011 .
Radotić, Ksenija, Melo, Thor Bernt, Leblanc, Roger M., Yousef, Yaser A., Naqvi, K. Razi, "Fluorescence and phosphorescence of tryptophan in peptides of different length and sequence" in Journal of Photochemistry and Photobiology B-Biology, 157 (2016):120-128,
https://doi.org/10.1016/j.jphotobiol.2016.02.011 . .
11
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9

Fluorescence and phosphorescence of tryptophan in peptides of different length and sequence (vol 157, pg 120, 2016)

Radotić, Ksenija; Melo, Thor Bernt; Leblanc, Roger M.; Yousef, Yaser A.; Naqvi, K. Razi

(Elsevier Science Sa, Lausanne, 2016)

TY  - JOUR
AU  - Radotić, Ksenija
AU  - Melo, Thor Bernt
AU  - Leblanc, Roger M.
AU  - Yousef, Yaser A.
AU  - Naqvi, K. Razi
PY  - 2016
UR  - http://rimsi.imsi.bg.ac.rs/handle/123456789/979
PB  - Elsevier Science Sa, Lausanne
T2  - Journal of Photochemistry and Photobiology B-Biology
T1  - Fluorescence and phosphorescence of tryptophan in peptides of different length and sequence (vol 157, pg 120, 2016)
EP  - 281
SP  - 281
VL  - 158
DO  - 10.1016/j.jphotobiol.2016.03.034
ER  - 
@article{
author = "Radotić, Ksenija and Melo, Thor Bernt and Leblanc, Roger M. and Yousef, Yaser A. and Naqvi, K. Razi",
year = "2016",
publisher = "Elsevier Science Sa, Lausanne",
journal = "Journal of Photochemistry and Photobiology B-Biology",
title = "Fluorescence and phosphorescence of tryptophan in peptides of different length and sequence (vol 157, pg 120, 2016)",
pages = "281-281",
volume = "158",
doi = "10.1016/j.jphotobiol.2016.03.034"
}
Radotić, K., Melo, T. B., Leblanc, R. M., Yousef, Y. A.,& Naqvi, K. R.. (2016). Fluorescence and phosphorescence of tryptophan in peptides of different length and sequence (vol 157, pg 120, 2016). in Journal of Photochemistry and Photobiology B-Biology
Elsevier Science Sa, Lausanne., 158, 281-281.
https://doi.org/10.1016/j.jphotobiol.2016.03.034
Radotić K, Melo TB, Leblanc RM, Yousef YA, Naqvi KR. Fluorescence and phosphorescence of tryptophan in peptides of different length and sequence (vol 157, pg 120, 2016). in Journal of Photochemistry and Photobiology B-Biology. 2016;158:281-281.
doi:10.1016/j.jphotobiol.2016.03.034 .
Radotić, Ksenija, Melo, Thor Bernt, Leblanc, Roger M., Yousef, Yaser A., Naqvi, K. Razi, "Fluorescence and phosphorescence of tryptophan in peptides of different length and sequence (vol 157, pg 120, 2016)" in Journal of Photochemistry and Photobiology B-Biology, 158 (2016):281-281,
https://doi.org/10.1016/j.jphotobiol.2016.03.034 . .
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