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Literatura académica sobre el tema "Fluorescence yield"

Autor: Grafiati

Publicado: 25 de mayo de 2024

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Artículos de revistas sobre el tema "Fluorescence yield"

1

OWENS, JOHN W. y MARSHA ROBINS. "Phthalocyanine photophysics and photosensitizer efficiency on human embryonic lung fibroblasts". Journal of Porphyrins and Phthalocyanines 05, n.º 05 (mayo de 2001): 460–64. http://dx.doi.org/10.1002/jpp.340.

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This study correlates the photophysical properties of aluminum phthalocyanine tetrasulfonate (AlPcTs), zinc phthalocyanine tetrasulfonate (ZnPcTs), and phthalocyanine tetrasulfonate (PcTs) with their ability to kill human embryonic lung (HEL) cells. Photofrin, a proven anti-cancer drug, was used for comparison. The photophysical properties include fluorescence emission spectra, fluorescence quantum yields, singlet state and radiative lifetimes, quantum yield for triplet formation, and fluorescence rate constants. Results indicate that photodynamic efficacy correlates inversely with fluorescence quantum yield and fluorescence lifetime and directly with quantum yield for triplet formation.

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2

MUKOYAMA, TAKESHI, HIROHIDE NAKAMATSU y HIROHIKO ADACHI. "CHEMICAL EFFECT ON X-RAY FLUORESCENCE YIELDS FOR CARBON". International Journal of PIXE 06, n.º 03n04 (enero de 1996): 447–52. http://dx.doi.org/10.1142/s012908359600048x.

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The chemical effect on K-shell fluorescence yields for carbon compounds has been estimated in a simple model based on the discrete-variational Xα molecular orbital calculations and the statistical scaling method. The calculated results show that there is a relation between the fluorescence yield and the effective number of 2p electrons in carbon, n2p. The behavior of the fluorescence yield as a function of n2p is in qualitatively agreement with the experimental data by proton impact. The present values for fluorescence yields of carbon oxides agree with other theoretical values.

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3

Kempe, Daryan, Antonie Schöne, Jörg Fitter y Matteo Gabba. "Accurate Fluorescence Quantum Yield Determination by Fluorescence Correlation Spectroscopy". Journal of Physical Chemistry B 119, n.º 13 (24 de marzo de 2015): 4668–72. http://dx.doi.org/10.1021/acs.jpcb.5b02170.

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Li, Tongtong, Baosheng Liu, Shaotong Duan y Mengmeng Cui. "Fluorescence spectra, fluorescence quantum yield and dissociation constant of sarafloxacin". Luminescence 32, n.º 4 (10 de octubre de 2016): 545–48. http://dx.doi.org/10.1002/bio.3211.

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5

Hott, J. L. y R. F. Borkman. "The non-fluorescence of 4-fluorotryptophan". Biochemical Journal 264, n.º 1 (15 de noviembre de 1989): 297–99. http://dx.doi.org/10.1042/bj2640297.

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The derivative 4-fluorotryptophan was confirmed to have negligible fluorescence at 25 degrees C and 285 nm (tryptophan/4-fluorotryptophan quantum-yield ratio greater than 100:1). However, photolysis experiments on tryptophan and 4-fluorotryptophan, in which loss of starting material was measured by reverse-phase h.p.l.c., demonstrated that 4-fluorotryptophan was significantly more photochemically active than the parent tryptophan, with the 4-fluorotryptophan photolysis quantum yield being 7 times larger than that of tryptophan at 25 degrees C and 285 nm. In addition, at 77 K and 275 nm 4-fluorotryptophan displayed strong fluorescence and phosphorescence, with emission quantum yields comparable with those of tryptophan at 77 K and 275 nm.

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6

Sen, Pinar, Nnamdi Nwahara y Tebello Nyokong. "Photodynamic antimicrobial activity of benzimidazole substituted phthalocyanine when conjugated to Nitrogen Doped Graphene Quantum Dots against Staphylococcus aureus". Main Group Chemistry 20, n.º 2 (22 de julio de 2021): 175–91. http://dx.doi.org/10.3233/mgc-210030.

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In this study, peripherally benzimidazole unit substituted ZnPc (1) and its conjugation to nitrogen doped graphene quantum dot (NGQD) as potential phthalocyanine support via π-π stacking have been presented and fully characterized. The bottom-up solution-based synthesized NGQDs was conjugated non-covalently to zinc phthalocyanine to form NGQDs-Pc nanoconjugates. The photophysical and photochemical properties of both such as absorption, fluorescence, fluorescence life time, singlet oxygen quantum yields, triplet state quantum yields and exited state lifetimes were investigated in solutions. We observed a decrease in the fluorescence quantum yields with a corresponding increase in the triplet quantum yield and singlet oxygen quantum yield of the nanoconjugates in comparison to the phthalocyanine complex alone. Photodynamic antimicrobial chemotherapy activities (PACT) of ZnPc alone and its nanoconjugate were determined towards Staphylococcus aureus.

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7

Silva, Gustavo T. M., Cassio P. Silva, Karen M. Silva, Renan M. Pioli, Tássia S. Costa, Vinícius V. Marto, Adilson A. Freitas et al. "Fluorescence and Phosphorescence of Flavylium Cation Analogues of Anthocyanins". Photochem 2, n.º 2 (8 de junio de 2022): 423–34. http://dx.doi.org/10.3390/photochem2020029.

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Fluorescence spectra and lifetimes were determined for 16 synthetic flavylium cation analogues of anthocyanin plant pigments in dry acetonitrile acidified with trifluoroacetic acid (TFA). Phosphorescence was also observed from the lowest excited triplet state for all of the flavylium cations at 77 K in a rigid TFA-acidified isopropanol glass. The fluorescence quantum yields and lifetimes depend in a systematic manner on the nature and position of the substituents on the flavylium chromophore and three specific substitution patterns associated with significant decreases in the fluorescence quantum yield were identified. A 4′-bromo or 4′-iodo substituent in the B-ring of the flavylium cation produced a small but normal heavy-atom effect, reducing the fluorescence quantum yield and the phosphorescence lifetime relative to analogues without the halogen atom. In contrast, three flavylium cations with a 3′-bromo substituent exhibited an “inverse” heavy atom effect, i.e., an increase in the fluorescence quantum yield rather than a decrease, which was rationalized on the basis of the nodal properties of the natural transition orbitals (NTOs) involved in the S0→S1 radiative transition.

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8

Falkowski, Paul G., Hanzhi Lin y Maxim Y. Gorbunov. "What limits photosynthetic energy conversion efficiency in nature? Lessons from the oceans". Philosophical Transactions of the Royal Society B: Biological Sciences 372, n.º 1730 (14 de agosto de 2017): 20160376. http://dx.doi.org/10.1098/rstb.2016.0376.

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Constraining photosynthetic energy conversion efficiency in nature is challenging. In principle, two yield measurements must be made simultaneously: photochemistry, fluorescence and/or thermal dissipation. We constructed two different, extremely sensitive and precise active fluorometers: one measures the quantum yield of photochemistry from changes in variable fluorescence, the other measures fluorescence lifetimes in the picosecond time domain. By deploying the pair of instruments on eight transoceanic cruises over six years, we obtained over 200 000 measurements of fluorescence yields and lifetimes from surface waters in five ocean basins. Our results revealed that the average quantum yield of photochemistry was approximately 0.35 while the average quantum yield of fluorescence was approximately 0.07. Thus, closure on the energy budget suggests that, on average, approximately 58% of the photons absorbed by phytoplankton in the world oceans are dissipated as heat. This extraordinary inefficiency is associated with the paucity of nutrients in the upper ocean, especially dissolved inorganic nitrogen and iron. Our results strongly suggest that, in nature, most of the time, most of the phytoplankton community operates at approximately half of its maximal photosynthetic energy conversion efficiency because nutrients limit the synthesis or function of essential components in the photosynthetic apparatus. This article is part of the themed issue ‘Enhancing photosynthesis in crop plants: targets for improvement’.

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9

Ma, Lihua. "The Investigation of Fluorescence Spectra and Fluorescence Quantum Yield of Enrofloxacin". Journal of Chemical, Environmental and Biological Engineering 2, n.º 1 (2018): 11. http://dx.doi.org/10.11648/j.jcebe.20180201.13.

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10

Hurtubise, R. J. y S. M. Ramasamy. "Comparison of Fluorescence-to-Phosphorescence Quantum Yield Ratios in Solid-Matrix Luminescence as a Function of Temperature". Applied Spectroscopy 47, n.º 3 (marzo de 1993): 283–86. http://dx.doi.org/10.1366/0003702934066587.

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An equation that relates the ratio of fluorescence to phosphorescence quantum yields as function of temperature to basic photophysical parameters is considered. The quantum yields were obtained from three compounds on three different solid matrices. Fluorescence quantum yields did not change much with temperature, while phosphorescence quantum yields changed more substantially with temperature. For some of the systems considered, it was possible to show that, as the temperature was lowered, the quantum yield ratio was only a function of the phosphorescence lifetime of the phosphor. However, with other systems, the quantum yield ratio was dependent on both the rate constant of intersystem crossing from the singlet state to the triplet state and the phosphorescence lifetime. The equation discussed is important in defining the fundamental parameters that cause the luminescence quantum yield ratio to change as temperature is lowered.

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Tesis sobre el tema "Fluorescence yield"

1

Biesen, Petrus Roverius van den. "Yield of fluorescence from various tissue layers during fluorescence angiography of the ocular fundus". Maastricht : Maastricht : Rijksuniversiteit Limburg ; University Library, Maastricht University [Host], 1995. http://arno.unimaas.nl/show.cgi?fid=5787.

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2

Waldenmaier, Tilo. "Spectral resolved measurement of the nitrogen fluorescence yield in air induced by electrons". Karlsruhe FZKA, 2006. http://nbn-resolving.de/urn:nbn:de:0005-072092.

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3

Obermeier, Andreas. "The fluorescence yield of air excited by electrons measured with the AIRFLY experiment". Karlsruhe Forschungszentrum Karlsruhe, 2007. http://d-nb.info/983981825/34.

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4

Bone, Emma Lewis. "A novel approach to investigating chlorophyll-a fluorescence quantum yield variability in the Southern Ocean". Doctoral thesis, Faculty of Science, 2019. http://hdl.handle.net/11427/31089.

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The apparent fluorescence quantum yield of chlorophyll-a (ΦF ), i.e. the ratio of photons emitted as chlorophyll-a fluorescence to those absorbed by phytoplankton, serves as a first order measure of photosynthetic efficiency and a photophysiological indicator of the resident phytoplankton community. Drivers of ΦF variability, including taxonomy, nutrient availability, and light history, differ in magnitude of influence across various biogeographic provinces and seasons. A Multi-Exciter Fluorometer (MFL, JFE Advantech Co., Ltd.) was selected for use in in situ ΦF derivation and underwent an extensive radiometric calibration for this purpose. Wavelength-specific ΦF was determined for 66 in situ field stations, sampled in the Atlantic Southern Ocean during the austral winter of 2012 and summer of 2013/ 2014. Phytoplankton pigments, macronutrient concentrations, and light levels were simultaneously measured to investigate their influence on ΦF . While no relationship was observed between macronutrient levels and ΦF , an inverse relationship between light and ΦF was apparent. This was likely due to the influence of speciesspecific fluorescence quenching mechanisms employed by local populations. ΦF derived from ocean colour products (Φsat) from the Moderate Resolution Imaging Spectroradiometer (MODIS) were compared to in situ ΦF to assess the performance of three existing Φsat algorithms. Results indicate that accounting for chlorophyll-a fluorescence reabsorption, the inherent optical properties of the surrounding water column, and the sensor angle of observation, is crucial to reducing Φsat uncertainty. A hybrid combination of two of the algorithms performed best, and was used to derive Φsat for stations co-located to in situ iron measurements in the Atlantic Southern Ocean. A significant negative relationship was observed, indicative of the effects of iron availability on quantum yield and its potential as a proxy for iron limitation. However, separating the individual contributions of light, taxonomy, and iron limitation to Φsat variability remains a challenge. A time series analysis of Φsat was also undertaken, which revealed a prominent Φsat seasonal cycle. Ultimately, increased in situ sampling would expedite the development of improved Φsat algorithms; the routine retrieval of Φsat would offer insight into phytoplankton dynamics in undersampled regions such as the climate relevant Southern Ocean.

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5

Rhoul, Camill. "Simulation de la fluorescence de la végétation mesurée depuis une orbite géostationnaire". Thesis, Université Paris-Saclay (ComUE), 2016. http://www.theses.fr/2016SACLX097/document.

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Le travail de cette thèse porte sur l’étude de la télédétection de la fluorescence chlorophyllienne avec un instrument imageur passif depuis une orbite géostationnaire pour le suivi de l’état physiologique de la végétation. Le concept instrumental est étudié théoriquement pour aboutir à la création d’uninstrument et à sa validation. La possibilité de mesurer des cycles diurnes de la fluorescence végétale depuis une orbite géostationnaire est évaluée à l’aide de simulations qui permettent de dresser les spécifications d’un instrument spatial.L’instrument imageur passif mesure dans la bande O 2 -A d’absorption atmosphérique. Il utilise une roue à filtres interférentiels dont la fonction de transmittance varie avec l’angle d’incidence des rayons les traversant. L’étude théorique a permis d’optimiser le placement spectral des filtres en vuede minimiser l’incertitude liée à la mesure de fluorescence.Grâce à la comparaison des mesures de l’instrument imageur avec d’autres instrument de mesure de la fluorescence, l’instrument et son concept instrumental ont été validés. Néanmoins, à cause d’effets de structure de la végétation intervenant sur le transfert radiatif de la fluorescence et de la lumière solaire au sein du couvert végétal, ces mesures ont confirmé la difficulté d’estimer le rendement de fluorescence de la végétation à partir des flux de fluorescence mesurés.Une étude théorique menée grâce à une modélisation du transfert radiatif de la fluorescence dans le couvert végétal jusqu’au capteur a permis d’expliquer la difficulté à retrouver le rendement de fluorescence à partir des flux. Cette étude a mis en avant l’accessibilité du rendement pour des couverts à fortedensité de feuilles et lorsque la distribution de l’orientation des feuilles est centrée sur l’horizontale.Cette modélisation a été étendue pour simuler des mesures spatiales dans le but d’étudier la possibilité de mesurer la fluorescence depuis une orbite géostationnaire dans les bandes O 2 -A et O 2 -B. Les résultats de ces simulations montrent la possibilité de mesurer préférentiellement dans la bandeO 2 -A avec une faible incertitude sur les flux de fluorescence et une bonne répétabilité temporelle pour le suivi des cycles diurnes de la fluorescence de la végétation
Le travail de cette thèse porte sur l’étude de la télédétection de la fluorescence chlorophyllienne avec un instrument imageur passif depuis une orbite géostationnaire pour le suivi de l’état physiologique de la végétation. Le concept instrumental est étudié théoriquement pour aboutir à la création d’uninstrument et à sa validation. La possibilité de mesurer des cycles diurnes de la fluorescence végétale depuis une orbite géostationnaire est évaluée à l’aide de simulations qui permettent de dresser les spécifications d’un instrument spatial.L’instrument imageur passif mesure dans la bande O 2 -A d’absorption atmosphérique. Il utilise une roue à filtres interférentiels dont la fonction de transmittance varie avec l’angle d’incidence des rayons les traversant. L’étude théorique a permis d’optimiser le placement spectral des filtres en vuede minimiser l’incertitude liée à la mesure de fluorescence.Grâce à la comparaison des mesures de l’instrument imageur avec d’autres instrument de mesure de la fluorescence, l’instrument et son concept instrumental ont été validés. Néanmoins, à cause d’effets de structure de la végétation intervenant sur le transfert radiatif de la fluorescence et de la lumière solaire au sein du couvert végétal, ces mesures ont confirmé la difficulté d’estimer le rendement de fluorescence de la végétation à partir des flux de fluorescence mesurés.Une étude théorique menée grâce à une modélisation du transfert radiatif de la fluorescence dans le couvert végétal jusqu’au capteur a permis d’expliquer la difficulté à retrouver le rendement de fluorescence à partir des flux. Cette étude a mis en avant l’accessibilité du rendement pour des couverts à fortedensité de feuilles et lorsque la distribution de l’orientation des feuilles est centrée sur l’horizontale.Cette modélisation a été étendue pour simuler des mesures spatiales dans le but d’étudier la possibilité de mesurer la fluorescence depuis une orbite géostationnaire dans les bandes O 2 -A et O 2 -B. Les résultats de ces simulations montrent la possibilité de mesurer préférentiellement dans la bandeO 2 -A avec une faible incertitude sur les flux de fluorescence et une bonne répétabilité temporelle pour le suivi des cycles diurnes de la fluorescence de la végétation

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6

Mutava, Raymond N. "Characterization of grain sorghum for physiological and yield traits associated with drought tolerance". Thesis, Manhattan, Kan. : Kansas State University, 2009. http://hdl.handle.net/2097/1458.

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7

Waldenmaier, Tilo [Verfasser]. "Spectral resolved measurement of the nitrogen fluorescence yield in air induced by electrons / Forschungszentrum Karlsruhe GmbH, Karlsruhe. Tilo Waldenmaier". Karlsruhe : FZKA, 2006. http://d-nb.info/980713544/34.

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8

Rhoul, Camill. "Simulation de la fluorescence de la végétation mesurée depuis une orbite géostationnaire". Electronic Thesis or Diss., Université Paris-Saclay (ComUE), 2016. http://www.theses.fr/2016SACLX097.

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Le travail de cette thèse porte sur l’étude de la télédétection de la fluorescence chlorophyllienne avec un instrument imageur passif depuis une orbite géostationnaire pour le suivi de l’état physiologique de la végétation. Le concept instrumental est étudié théoriquement pour aboutir à la création d’uninstrument et à sa validation. La possibilité de mesurer des cycles diurnes de la fluorescence végétale depuis une orbite géostationnaire est évaluée à l’aide de simulations qui permettent de dresser les spécifications d’un instrument spatial.L’instrument imageur passif mesure dans la bande O 2 -A d’absorption atmosphérique. Il utilise une roue à filtres interférentiels dont la fonction de transmittance varie avec l’angle d’incidence des rayons les traversant. L’étude théorique a permis d’optimiser le placement spectral des filtres en vuede minimiser l’incertitude liée à la mesure de fluorescence.Grâce à la comparaison des mesures de l’instrument imageur avec d’autres instrument de mesure de la fluorescence, l’instrument et son concept instrumental ont été validés. Néanmoins, à cause d’effets de structure de la végétation intervenant sur le transfert radiatif de la fluorescence et de la lumière solaire au sein du couvert végétal, ces mesures ont confirmé la difficulté d’estimer le rendement de fluorescence de la végétation à partir des flux de fluorescence mesurés.Une étude théorique menée grâce à une modélisation du transfert radiatif de la fluorescence dans le couvert végétal jusqu’au capteur a permis d’expliquer la difficulté à retrouver le rendement de fluorescence à partir des flux. Cette étude a mis en avant l’accessibilité du rendement pour des couverts à fortedensité de feuilles et lorsque la distribution de l’orientation des feuilles est centrée sur l’horizontale.Cette modélisation a été étendue pour simuler des mesures spatiales dans le but d’étudier la possibilité de mesurer la fluorescence depuis une orbite géostationnaire dans les bandes O 2 -A et O 2 -B. Les résultats de ces simulations montrent la possibilité de mesurer préférentiellement dans la bandeO 2 -A avec une faible incertitude sur les flux de fluorescence et une bonne répétabilité temporelle pour le suivi des cycles diurnes de la fluorescence de la végétation
Le travail de cette thèse porte sur l’étude de la télédétection de la fluorescence chlorophyllienne avec un instrument imageur passif depuis une orbite géostationnaire pour le suivi de l’état physiologique de la végétation. Le concept instrumental est étudié théoriquement pour aboutir à la création d’uninstrument et à sa validation. La possibilité de mesurer des cycles diurnes de la fluorescence végétale depuis une orbite géostationnaire est évaluée à l’aide de simulations qui permettent de dresser les spécifications d’un instrument spatial.L’instrument imageur passif mesure dans la bande O 2 -A d’absorption atmosphérique. Il utilise une roue à filtres interférentiels dont la fonction de transmittance varie avec l’angle d’incidence des rayons les traversant. L’étude théorique a permis d’optimiser le placement spectral des filtres en vuede minimiser l’incertitude liée à la mesure de fluorescence.Grâce à la comparaison des mesures de l’instrument imageur avec d’autres instrument de mesure de la fluorescence, l’instrument et son concept instrumental ont été validés. Néanmoins, à cause d’effets de structure de la végétation intervenant sur le transfert radiatif de la fluorescence et de la lumière solaire au sein du couvert végétal, ces mesures ont confirmé la difficulté d’estimer le rendement de fluorescence de la végétation à partir des flux de fluorescence mesurés.Une étude théorique menée grâce à une modélisation du transfert radiatif de la fluorescence dans le couvert végétal jusqu’au capteur a permis d’expliquer la difficulté à retrouver le rendement de fluorescence à partir des flux. Cette étude a mis en avant l’accessibilité du rendement pour des couverts à fortedensité de feuilles et lorsque la distribution de l’orientation des feuilles est centrée sur l’horizontale.Cette modélisation a été étendue pour simuler des mesures spatiales dans le but d’étudier la possibilité de mesurer la fluorescence depuis une orbite géostationnaire dans les bandes O 2 -A et O 2 -B. Les résultats de ces simulations montrent la possibilité de mesurer préférentiellement dans la bandeO 2 -A avec une faible incertitude sur les flux de fluorescence et une bonne répétabilité temporelle pour le suivi des cycles diurnes de la fluorescence de la végétation

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9

Miasojedovas, Arūnas. "Control of fluorescence properties of organic optoelectronic materials by molecular aggregate formation". Doctoral thesis, Lithuanian Academic Libraries Network (LABT), 2013. http://vddb.laba.lt/obj/LT-eLABa-0001:E.02~2013~D_20130930_092153-02661.

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Currently, organic electronics is one of the most expanding technology of semiconductor devices. This direction is rapidly developing due to the constant synthesis of new organic compounds and sophisticated advances in device engineering. Currently, organic materials are used in organic light-emitting diodes (OLEDs), organic thin-film transistors, solar cells and sensors. Low-cost manufacturing techniques such as wet casting or inkjet printing enable organic materials use in large-area and flexible electronic devices. Modern organic electronic materials are multifunctional – this enables not only to improve the material properties, but also to simplify the device architecture. However, the complexity of the molecular structure brings new problems associated with complex phenomena of the new multifunctional molecules -such as the formation of aggregates, intramolecular charge transfer, intramolecular torsion and others. Therefore, the control of the features of new multifunctional molecules is the main problem of organic electronics today. This work focuses on the control of photophysical characteristics of multifunctional organic emitters. Here we study aggregation induced emission and quenching of multifunctional molecular emitters and the possibilities to control these phenomena by optimizing functional properties of the film such as film forming properties, charge transfer, the emission efficiency, amplified spontaneous emission threshold and others.
Organinė elektronika pastaruoju metu yra viena sparčiausiai besiplėtojančių puslaidininkių prietaisų krypčių. Ši kryptis labai sparčiai vystoma dėl nuolat kuriamų naujų organinių junginių ir tobulėjančių inžinerijos galimybių. Šiuo metu organinės medžiagos naudojamos organiniuose šviestukuose (OLED), plonasluoksniuose tranzistoriuose, saulės celėse, jutikliuose ir kt. Organinės medžiagos įgalina gaminti didelio ploto bei lanksčius elektronikos prietaisus, gamybai pasitelkiant pigias gaminimo technologijas. Modernios organinės elektronikos medžiagos yra daugiafunkcinės – tai leidžia ne tik pagerinti medžiagos savybes, bet ir supaprastinti technologiją, kur viename sluoksnyje daugiafunkcinė molekulė atlieka keletą funkcijų. Tačiau molekulinės struktūros sudėtingėjimas iškelia naujas problemas susijusias su naujais sudėtingais reiškiniais daugiafunkciniame molekuliniame darinyje, tokiais kaip agregatų formavimas, vidujemolekulinė krūvio pernaša, vidujemolekulinė sąsūka ir kt. Todėl naujų daugiafunkcinių molekulinių darinių savybių optimizavimas yra aktuali nūdienos organinės elektronikos problema. Šiame darbe didžiausias dėmesys skiriamas daugiafunkcinių organinių spinduolių fotofizikinių savybių valdymui. Čia nagrinėjami daugiafunkcinių molekulinių spinduolių agregacijos nulemti reiškiniai ir jų valdymo galimybės, optimizuojant sluoksnio funkcines savybes tokias kaip plėvėdaros savybės, krūvio pernaša, emisijos našumas, sustiprintos savaiminės spinduliuotės slenkstis ir kt.

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Uejima, Motoyuki. "Theoretical Design of Light-Emitting Molecules Based on Vibronic Coupling Density Analysis". 京都大学 (Kyoto University), 2014. http://hdl.handle.net/2433/188601.

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Más fuentes

Capítulos de libros sobre el tema "Fluorescence yield"

1

Gland, John L., Tecle Rufael y Daniel A. Fischer. "Ultrasoft X-ray Absorption Detected by Fluorescence Yield". En ACS Symposium Series, 183–201. Washington, DC: American Chemical Society, 1992. http://dx.doi.org/10.1021/bk-1992-0482.ch012.

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2

Avenson, Thomas J. y Aaron J. Saathoff. "Sub-saturating Multiphase Flash Irradiances to Estimate Maximum Fluorescence Yield". En Methods in Molecular Biology, 105–20. New York, NY: Springer New York, 2018. http://dx.doi.org/10.1007/978-1-4939-7786-4_7.

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3

Estupiñán-López, Carlos, Christian Tolentino Dominguez, Paulo E. Cabral Filho, Adriana Fontes y Renato E. de Araujo. "Quantum Dots Fluorescence Quantum Yield Measured by Thermal Lens Spectroscopy". En Quantum Dots: Applications in Biology, 93–101. New York, NY: Springer New York, 2014. http://dx.doi.org/10.1007/978-1-4939-1280-3_7.

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4

Karazija, Romas. "The width and Shape of the Lines. The Fluorescence Yield". En Introduction to the Theory of X-Ray and Electronic Spectra of Free Atoms, 233–50. Boston, MA: Springer US, 1996. http://dx.doi.org/10.1007/978-1-4899-1534-4_9.

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5

Buschmann, C. y H. Prehn. "Inverse Yield Changes of Heat and Fluorescence During Photoinhibition of Photosynthesis". En Photoacoustic and Photothermal Phenomena, 523–26. Berlin, Heidelberg: Springer Berlin Heidelberg, 1988. http://dx.doi.org/10.1007/978-3-540-48181-2_141.

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de Araujo, Renato E. y Christian T. Dominguez. "Absolute and Relative Methods for Fluorescence Quantum Yield Evaluation of Quantum Dots". En Quantum Dots, 37–51. New York, NY: Springer US, 2020. http://dx.doi.org/10.1007/978-1-0716-0463-2_2.

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Waychunas, Glenn A. y Gordon E. Brown. "Fluorescence Yield Xanes and EXAFS Experiments: Application To Highly Dilute and Surface Samples". En Advances in X-Ray Analysis, 607–17. Boston, MA: Springer US, 1994. http://dx.doi.org/10.1007/978-1-4615-2528-8_73.

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8

Deák, Zsuzsanna y Imre Vass. "Oscillating Yield of Flash-Induced Chlorophyll Fluorescence Decay in Intact Cells of Thermosynechococcus elongatus". En Photosynthesis. Energy from the Sun, 573–76. Dordrecht: Springer Netherlands, 2008. http://dx.doi.org/10.1007/978-1-4020-6709-9_129.

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Maske, H. y H. Haardt. "Quantum Yield of in Situ Fluorescence of Pyhtoplankton in Kiel Bay Under Daylight, Comparison with Primary Production". En Applications of Chlorophyll Fluorescence in Photosynthesis Research, Stress Physiology, Hydrobiology and Remote Sensing, 275–84. Dordrecht: Springer Netherlands, 1988. http://dx.doi.org/10.1007/978-94-009-2823-7_35.

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Gui-Ying, Ben, C. Barry Osmond y Thomas D. Sharkey. "Effects of Water Stress on in Vivo Photosynthetic Biochemistry (Maximum Photosynthesis, Quantum Yield and 77 K Fluorescence)". En Progress in Photosynthesis Research, 157–60. Dordrecht: Springer Netherlands, 1987. http://dx.doi.org/10.1007/978-94-017-0519-6_34.

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Actas de conferencias sobre el tema "Fluorescence yield"

1

Paithankar, D. Y. y E. M. Sevick-Muraca. "Fluorescence lifetime imaging with frequency-domain photon migration measurement". En Biomedical Optical Spectroscopy and Diagnostics. Washington, D.C.: Optica Publishing Group, 2006. http://dx.doi.org/10.1364/bosd.1996.fg3.

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The feasibility of employing fluorescent contrast agents to perform optical imaging in tissues and other scattering media has been examined through computational studies. Fluorescence lifetime and yield can give crucial information about local metabolite concentration or environmental conditions within tissues. This information can be employed towards disease detection, diagnosis, and treatment if non- invasively quantitated from re-emitted optical signals. However, the problem of inverse image reconstruction of fluorescence yield and lifetime is complicated due to the highly scattering nature of the tissue. In this work, a light propagation model employing the diffusion equation is used to account for the scattering of both the excitation and fluorescent light. Simulated measurements of frequency-domain parameters of fluorescent modulated AC intensity and phase-lag are used as inputs to an inverse image reconstruction algorithm which employs the diffusion model to relate frequency-domain measurements resulting from a modulated input at the phantom periphery. In the inverse image reconstruction algorithm, we employ a Newton-Raphson technique combined with Marquardt algorithm to converge upon the fluorescent properties within the medium. The successful reconstruction of both the fluorescence yield and lifetime in the case of heterogeneous fluorophore distribution within a scattering medium has been demonstrated without a priori information or without the necessity of obtaining "absence" images.

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2

Ave, M., M. Bohacova, K. Daumiller, P. Di Carlo, C. Di Giulio, P. Facal San Luis, D. Gonzales et al. "Precise Measurement of the Absolute Fluorescence Yield". En INTERNATIONAL SYMPOSIUM ON THE RECENT PROGRESS OF ULTRA-HIGH ENERGY COSMIC RAY OBSERVATION. AIP, 2011. http://dx.doi.org/10.1063/1.3628710.

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3

Cady, R., Hiroyuki Sagawa, Yoshiya Kawasaki, Takashi Sako, Masahiro Takeda y Yoshiki Tsunesada. "A World Average of Fluorescence Yield Measurements". En INTERNATIONAL SYMPOSIUM ON THE RECENT PROGRESS OF ULTRA-HIGH ENERGY COSMIC RAY OBSERVATION. AIP, 2011. http://dx.doi.org/10.1063/1.3628712.

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Jui, Charles, Masaki Fukushima y Pierre Sokolsky. "SFLASH: Absolute Fluorescence Yield Measurement of Shower Particles." En 35th International Cosmic Ray Conference. Trieste, Italy: Sissa Medialab, 2017. http://dx.doi.org/10.22323/1.301.0300.

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Maier, John S., Albert E. Cerussi, Sergio Fantini, Maria Angela Franceschini y Enrico Gratton. "Quantitative Fluorescence in Tissue-Like Media". En Biomedical Optical Spectroscopy and Diagnostics. Washington, D.C.: Optica Publishing Group, 2006. http://dx.doi.org/10.1364/bosd.1996.fg6.

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We present a study focused on quantitative fluorescence in tissues at near-infrared wavelengths. We demonstrate the quantitative description of fluorescence in tissue-like media provided by a model derived from diffusion theory. Based on this model we conclude that the spatial distribution of the fluorescent light does not depend on the lifetime of the probe. We also show that lifetime and quantum yield or probe concentration can be determined in a highly scattering medium using frequency-domain techniques, without the use of a reference probe.

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6

Pushkarevskaya, A. A., A. V. Aralov y A. A. Lomzov. "HYBRIDIZATION AND FLUORESCENCE PROPERTIES OF MODIFIED OLIGODEOXYRIBONUCLEOTIDES CONTAINING A N6-MODIFIED ADENINE". En X Международная конференция молодых ученых: биоинформатиков, биотехнологов, биофизиков, вирусологов и молекулярных биологов — 2023. Novosibirsk State University, 2023. http://dx.doi.org/10.25205/978-5-4437-1526-1-207.

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The properties of oligodeoxyribonucleotides containing an analog of N6-modified adenine studied. The thermodynamic parameters of duplexes formation containing a fluorescent nucleoside have been determined, and the fluorescence quantum yield of a nucleotide, oligonucleotides and duplexes containing it were determined. The potential of using such oligomers as fluorescent probes has been demonstrated.

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7

Komori, Kohei. "Systematic uncertainty in the analysis of the TA fluorescence detector from fluorescence yield models". En 38th International Cosmic Ray Conference. Trieste, Italy: Sissa Medialab, 2023. http://dx.doi.org/10.22323/1.444.0330.

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Monahan, Tim, Shudong Jiang y Brian Pogue. "Fluorescence quantum yield of verteporfin is independent of oxygen". En Biomedical Optics (BiOS) 2008, editado por David Kessel. SPIE, 2008. http://dx.doi.org/10.1117/12.764244.

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Drobizhev, Mikhail, J. Nathan Scott, Patrik R. Callis, Rosana S. Molina y Thomas E. Hughes. "Role of Local Electric Field in Controlling Fluorescence Quantum Yield of Red Fluorescent Proteins". En Optical Molecular Probes, Imaging and Drug Delivery. Washington, D.C.: OSA, 2019. http://dx.doi.org/10.1364/omp.2019.ot2d.5.

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Zucolotto Cocca, Leandro H., André G. Pelosi, Sandrine Piguel, Cleber Renato Mendonça y Leonardo De Boni. "Two - photon Brightness is increased in push-pull purines nucleobases". En Latin America Optics and Photonics Conference. Washington, D.C.: Optica Publishing Group, 2022. http://dx.doi.org/10.1364/laop.2022.tu4a.54.

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Nowadays, purines nucleobases have received great attention owing their capacity to be employed as fluorescent bioprobes for nucleic acid spectroscopic studies. Here we determine the fluorescence quantum yield and two-photon brightness in four purines nucleobases.

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Informes sobre el tema "Fluorescence yield"

1

Reil, K. Measurements of the Fluorescence Light Yield in Electromagnetic Showers. Office of Scientific and Technical Information (OSTI), marzo de 2005. http://dx.doi.org/10.2172/839935.

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Huntemeyer, P. An Experiment to Measure the Air Fluorescence Yield in Electromagnetic Showers. Office of Scientific and Technical Information (OSTI), junio de 2004. http://dx.doi.org/10.2172/826972.

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3

Frost, Bruce. Time- and Irradiance-Dependent Behavior of the Quantum Yield of Chlorophyll alpha Fluorescence. Fort Belvoir, VA: Defense Technical Information Center, septiembre de 2001. http://dx.doi.org/10.21236/ada627704.

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4

Perry, Mary J. Time- and Irradiance-Dependent Behavior of the Quantum Yield of Chlorophyll alpha Fluorescence. Fort Belvoir, VA: Defense Technical Information Center, agosto de 2001. http://dx.doi.org/10.21236/ada628016.

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Paterson, Andrew H., Yehoshua Saranga y Dan Yakir. Improving Productivity of Cotton (Gossypsum spp.) in Arid Region Agriculture: An Integrated Physiological/Genetic Approach. United States Department of Agriculture, diciembre de 1999. http://dx.doi.org/10.32747/1999.7573066.bard.

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Objectives: We seek to establish the basis for improving cotton productivity under arid conditions, by studying the water use efficiency - evaporative cooling interrelationship. Specifically, we will test the hypothesis that cotton productivity under arid conditions can be improved by combining high seasonal WUE with efficient evaporative cooling, evaluate whether high WUE and/or evaporative cooling are based on specific physiological factors such as diurnal flexibility in stomatal conductance, stomatal density, photosynthetic capacity, chlorophyll fluorescence, and plant water status. Genes influencing both WUE and evaporative cooling, as well as other parameters such as economic products (lint yield, quality, harvest index) of cotton will also be mapped, in order to evaluate influences of water relations on these parameters. Approach: Carbon isotope ratio will be used to evaluate WUE, accompanied by additional parameters to elucidate the relationship between WUE, evaporative cooling, and cotton productivity. A detailed RFLP map will be used to determine the number, location, and phenotypic effects of genes underlying genetic variation in WUE between cultivated cottons, as well as test associations of these genes with traits of economic importance such as harvest index, lint yield, and lint quality. Major Conclusions: Productivity and quality of cotton grown under well-watered versus water-limited conditions was shown to be partly accounted for by different quantitative trait loci (QTLs). Among a suite of physiological traits often found to differ between genotypes adapted to arid versus well-watered conditions, genetic mapping implicated only reduced plant osmotic potential in improved cotton productivity under arid conditions. Our findings clearly implicate OP as a major component of cotton adaptation to arid conditions. However, testing of further physiological hypotheses is clearly needed to account for additional QTL alleles conferring higher seed-cotton yield under arid conditions, such as three of the five we found. Near-isogenic lines being made for QTLs discovered herein will offer a powerful new tool useful toward identification of the underlying gene(s) by using fine-scale mapping approaches (Paterson et al 1990). Implications: Adaptation to both arid and favorable conditions can be combined into the same genotype. We have identified diagnostic DNA markers that are being applied to creation of such desirable genotypes. Simultaneous improvement of productivity (and/or quality) for both arid and irrigated conditions will require more extensive field testing and the manipulation of larger numbers of genes, reducing the expected rate of genetic gain These difficulties may be at least partly ameliorated by efficiencies gained through identification and use of diagnostic DNA markers. Genomic tools and approaches may expedite adaptation of crops to arid cultivation, help to test roles of additional physiological factors, and guide the isolation of the underlying genes that protect crop performance under arid conditions.

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6

Pokrzywinski, Kaytee, West Bishop, Christopher Grasso, Kaitlin Volk y Kurt Getsinger. Chemical management strategies for starry stonewort : a mesocosm study. Engineer Research and Development Center (U.S.), septiembre de 2021. http://dx.doi.org/10.21079/11681/42040.

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US Environmental Protection Agency (USEPA) approved algaecides and herbicides are frequently utilized to manage nuisance algae and aquatic macrophytes. However, there is limited information available on the effectiveness of these products for the management of starry stonewort. Thus, the goal of this research was to discern effective chemical control products for later growth stages of starry stonewort using mesocosm studies. Eleven treatments were evaluated using various combinations of four copper-based products, endothall, diquat, and carfentrazone – all with USEPA registrations for use in aquatic sites. To assess treatment efficacy, water quality, photophysiology, biomass changes, and bulbil viability were evaluated. Nine of the eleven treatments yielded lower dissolved oxygen concentrations and higher specific conductance when compared to the control. Photophysiological response varied by condition, but seven of eleven treatments resulted in significantly lower fluorescent and maximum fluorescent yield. Five of these also exhibited significantly lower average photosynthetic yields, with combination treatments resulting in more drastic decreases. Ten of the eleven treatments had significantly less biomass compared to the control when measured via wet weight; however, only four treatments were significant when measured via dry weight. Lastly, all conditions utilizing copper-based products significantly reduced bulbil viability while non-copper products had no impact.

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7

Litaor, Iggy, James Ippolito, Iris Zohar y Michael Massey. Phosphorus capture recycling and utilization for sustainable agriculture using Al/organic composite water treatment residuals. United States Department of Agriculture, enero de 2015. http://dx.doi.org/10.32747/2015.7600037.bard.

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Objectives: 1) develop a thorough understanding of the sorption mechanisms of Pi and Po onto the Al/O- WTR; 2) determine the breakthrough range of the composite Al/O-WTR during P capturing from agro- wastewaters; and 3) critically evaluate the performance of the composite Al/O-WTR as a fertilizer using selected plants grown in lysimeters and test-field studies. Instead of lysimeters we used pots (Israel) and one- liter cone-tainers (USA). We conducted one field study but in spite of major pretreatments the soils still exhibited high enough P from previous experiments so no differences between control and P additions were noticeable. Due to time constrains the field study was discontinued. Background: Phosphorous, a non-renewable resource, has been applied extensively in fields to increase crop yield, yet consequently has increased the potential of waterway eutrophication. Our proposal impetus is the need to develop an innovative method of P capturing, recycling and reuse that will sustain agricultural productivity while concurrently reducing the level of P discharge from and to agricultural settings. Major Conclusions & Achievements: An innovative approach was developed for P removal from soil leachate, dairy wastewater (Israel), and swine effluents (USA) using Al-based water treatment residuals (Al- WTR) to create an organic-Al-WTR composite (Al/O-WTR), potentially capable of serving as a P fertilizer source. The Al-WTR removed 95% inorganic-P, 80% to 99.9% organic P, and over 60% dissolved organic carbon from the agro-industrial waste streams. Organic C accumulation on particles surfaces possibly enhanced weak P bonding and facilitated P desorption. Analysis by scanning electron microscope (SEM- EDS), indicated that P was sparsely sorbed on both calcic and Al (hydr)oxide surfaces. Sorption of P onto WW-Al/O-WTR was reversible due to weak Ca-P and Al-P bonds induced by the slight alkaline nature and in the presence of organic moieties. Synchrotron-based microfocused X-ray fluorescence (micro-XRF) spectrometry, bulk P K-edge X-ray absorption near edge structure spectroscopy (XANES), and P K-edge micro-XANES spectroscopy indicated that adsorption was the primary P retention mechanism in the Al- WTR materials. However, distinct apatite- or octocalciumphosphatelike P grains were also observed. Synchrotron micro-XRF mapping further suggested that exposure of the aggregate exteriors to wastewater caused P to diffuse into the porous Al-WTR aggregates. Organic P species were not explicitly identified via P K-edge XANES despite high organic matter content, suggesting that organic P may have been predominantly associated with mineral surfaces. In screen houses experiments (Israel) we showed that the highest additions of Al/O-WTR (5 and 7 g kg⁻¹) produced the highest lettuce (Lactuca sativa L. var. longifolial) yield. Lettuce yield and P concentration were similar across treatments, indicating that Al/O- WTR can provide sufficient P to perform similarly to common fertilizers. A greenhouse study (USA) was utilized to compare increasing rates of swine wastewater derived Al/O-WTR and inorganic P fertilizer (both applied at 33.6, 67.3, and 134.5 kg P₂O₅ ha⁻¹) to supply plant-available P to spring wheat (TriticumaestivumL.) in either sandy loam or sandy clay loam soil. Spring wheat straw and grain P uptake were comparable across all treatments in the sandy loam, while Al/O-WTR application to the sandy clay loam reduced straw and grain P uptake. The Al/O-WTR did not affect soil organic P concentrations, but did increase phosphatase activity in both soils; this suggests that Al/O-WTR application stimulated microorganisms and enhance the extent to which microbial communities can mineralize Al/O-WTR-bound organic P. Implications: Overall, results suggest that creating a new P fertilizer from Al-WTR and agro-industrial waste sources may be a feasible alternative to mining inorganic P fertilizer sources, while protecting the environment from unnecessary waste disposal.

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Hubbell, John H. Bibliography and current status of K, L, and higher shell fluorescence yields for computations of photon energy-absorption coefficients. Gaithersburg, MD: National Institute of Standards and Technology, 1989. http://dx.doi.org/10.6028/nist.ir.89-4144.

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Ardakani, O. H. Organic petrography and thermal maturity of the Paskapoo Formation in the Fox Creek area, west-central Alberta. Natural Resources Canada/CMSS/Information Management, 2022. http://dx.doi.org/10.4095/330296.

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The Paskapoo Formation, which ranges in age from middle to upper Paleocene, is the major shallow aquifer in Alberta. This study is part of a larger GSC-led study on the potential environmental impact of hydrocarbon development in the Fox Creek area (west-central Alberta) on shallow aquifers. Fox Creek is located near the northern limit of the Paskapoo Formation. In addition to the underlying organic-rich source rocks in the study area, including the Duvernay Formation that is currently exploited for hydrocarbon resources, the Paskapoo Formation contains organic-rich intervals and coal seams. In order to investigate any potential internal hydrocarbon sources within the Paskapoo Formation, ninety-seven (97) cutting samples from the formation obtained from eight shallow monitoring wells (50-90 m) in the study area were studied for total organic carbon (TOC) content, organic matter composition and thermal maturity of coal seams using programmed pyrolysis analysis and organic petrography. The TOC content of all samples ranges from 0.2 to 8.8 wt. %, with a mean value of 0.95 ± 1.6 wt. % (n=97). The Tmax values of studied samples range from 347 to 463 °C, with a mean value of 434 ± 20 °C that suggest a range of thermal maturity from immature to peak oil window. The random reflectance (Rr) measurement and fluorescence microscopy on eighteen (18) selected samples with TOC content &gt; ~1 wt. % shows a mean Rr value of 0.27% and 0.42% for the overlying till deposits and the underlying shallow depth sandstone, siltstone, shale and coal seams respectively, indicating a low rank coal ranging from lignite to sub-bituminous coal. Blue to green and yellow fluorescing liptinite macerals further confirmed the low maturity of studied samples. The low S2 yield of a large part of the samples (65%) resulted in unreliable Tmax values that overestimated the thermal maturity. Although the organic matter in the studied intervals are immature, exsudatinite, as secondary liptinite maceral, was observed in samples from the lower parts of the studied monitoring wells. Exsudatinite generally derives from the transformation of sporinite, alginite, resinite and varieties of vitrinite, which is a resinous or asphalt like material. Considering the thickness and distribution of coal seams in the studied samples, it is unlikely the exsudatinite will be a major source for aquifer hydrocarbon contamination in the study area. Additional stratigraphic studies and molecular geochemical analysis could provide an estimate of the total volume of possible organic compounds contribution to the aquifer in the study area. Due to the presence of coal seams in the studied intervals of the Paskapoo Formation, it is important to investigate the possibility of biogenic methane formation in Paskapoo shallow aquifers.

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Friedman, Haya, Chris Watkins, Susan Lurie y Susheng Gan. Dark-induced Reactive Oxygen Species Accumulation and Inhibition by Gibberellins: Towards Inhibition of Postharvest Senescence. United States Department of Agriculture, diciembre de 2009. http://dx.doi.org/10.32747/2009.7613883.bard.

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Dark-induced senescence could pose a major problem in export of various crops including cuttings. The assumption of this work was that ROS which is increased at a specific organelle can serve as a signal for activation of cell senescence program. Hormones which reduce senescence in several crops like gibberellic acid (GA) and possibly cytokinin (CK) may reduce senescence by inhibiting this signal. In this study we worked on Pelargonium cuttings as well as Arabidopsis rosette. In Pelargonium the increase in ROS occurred concomitantly with increase in two SAGs, and the increase persisted in isolated chloroplasts. In Arabidopsis we used two recentlydeveloped technologies to examine these hypotheses; one is a transcriptome approach which, on one hand, enabled to monitor expression of genes within the antioxidants network, and on the other hand, determine organelle-specific ROS-related transcriptome footprint. This last approach was further developed to an assay (so called ROSmeter) for determination of the ROS-footprint resulting from defined ROS stresses. The second approach involved the monitoring of changes in the redox poise in different organelles by measuring fluorescence ratio of redox-sensitive GFP (roGFP) directed to plastids, mitochondria, peroxisome and cytoplasm. By using the roGFP we determined that the mitochondria environment is oxidized as early as the first day under darkness, and this is followed by oxidation of the peroxisome on the second day and the cytoplast on the third day. The plastids became less oxidized at the first day of darkness and this was followed by a gradual increase in oxidation. The results with the ROS-related transcriptome footprint showed early changes in ROS-related transcriptome footprint emanating from mitochondria and peroxisomes. Taken together these results suggest that the first ROS-related change occurred in mitochondria and peroxisomes. The analysis of antioxidative gene’s network did not yield any clear results about the changes occurring in antioxidative status during extended darkness. Nevertheless, there is a reduction in expression of many of the plastids antioxidative related genes. This may explain a later increase in the oxidation poise of the plastids, occurring concomitantly with increase in cell death. Gibberellic acid (GA) prevented senescence in Pelargonium leaves; however, in Arabidopsis it did not prevent chlorophyll degradation, but prevented upregulation of SAGs (Apendix Fig. 1). Gibberellic acid prevented in Pelargonium the increase in ROS in chloroplast, and we suggested that this prevents the destruction of the chloroplasts and hence, the tissue remains green. In Arabidopsis, reduction in endogenous GA and BA are probably not causing dark-induced senescence, nevertheless, these materials have some effect at preventing senescence. Neither GA nor CK had any effect on transcriptome footprint related to ROS in the various organelles, however while GA reduced expression of few general ROS-related genes, BA mainly prevented the decrease in chloroplasts genes. Taken together, GA and BA act by different pathways to inhibit senescence and GA might act via ROS reduction. Therefore, application of both hormones may act synergistically to prevent darkinduced senescence of various crops.

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