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Influence of dental materials used for sealing caries lesions on laser fluorescence measurements

Celiberti, Paula; Carvalho, Thiago Saads; Raggio, Daniela Prócida; Mendes, Fausto Medeiros
Fonte: SPRINGER LONDON LTD; LONDON Publicador: SPRINGER LONDON LTD; LONDON
Tipo: Artigo de Revista Científica
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The aim of this study was to determine the influence of thickness and aging on the intrinsic fluorescence of sealing materials and their ability to block fluorescence from the underlying surface as assessed using a laser fluorescence device. Cavities of 0.5 mm and 1 mm depth were drilled into acrylic boards which were placed over two surfaces with different fluorescence properties: a low-fluorescence surface, to assess the intrinsic fluorescence of the sealing materials, and a high-fluorescence surface, to assess the fluorescence-blocking ability of the sealing materials. Ten cavities of each depth were filled with different sealing materials: Adper Scotchbond Multi-Purpose, Adper Single Bond 2, FluroShield, Conseal f and UltraSeal XT Plus. Fluorescence was measured with a DIAGNOdent pen at five different time points: empty cavity, after polymerization, and 1 day, 1 week and 1 month after filling. The individual values after polymerization, as well as the area under the curve for the different periods were submitted to ANOVA and the Tukey test (p < 0.05). At 0.5 mm, Scotchbond, FluroShield and UltraSeal showed insignificant changes in intrinsic fluorescence with aging and lower fluorescence after polymerization than Single Bond and Conseal. At 1 mm...

"Identificação e quantificação de fotossensibilizador em tecido hepático por espectroscopia de fluorescência e sua importância na terapia fotodinâmica"; "Photosensitizer identification and quantification in liver tissue by fluorescence spectroscopy and its importance on photodinamic therapy"

Vollet Filho, José Dirceu
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 26/02/2007 Português
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A Terapia Fotodinâmica (TFD) é uma técnica que provoca dano celular pela ação de um fotossensibilizador (FS), com seletividade de localização em tecido tumoral; a luz que, absorvida pelo FS, leva-o a um estado tripleto metaestável; e oxigênio molecular, o qual recebe a energia absorvida pelo FS, passando a um estado singleto de alta capacidade oxidativa. A técnica é bem sucedida no tratamento de lesões como câncer, mas enfrenta, entretanto, dificuldades para a determinação de sua dosimetria. Uma delas é a quantificação da distribuição do FS no tecido tratado. Este trabalho tem três objetivos: a obtenção de informação quantitativa por espectros de fluorescência de fluoróforos em meios turvos; a demonstração da distribuição do FS Photogem® em fígados sadios de ratos Wistar e suas implicações na dosimetria; e a melhoria de um dos modelos existentes para previsão da profundidade de necrose (Ynec), importante parâmetro no estudo da TFD. Realizaram-se os experimentos em três fases: na primeira, tentou-se reconstruir o espectro do fígado sadio a partir de uma composição de espectros isolados de fluoróforos endógenos do fígado. Na segunda, realizaram-se estudos com corantes alimentícios Coralim-Mix® nas cores azul...

Associação entre fluorescência vermelha emitida pela placa bacteriana e atividade de cárie: estudo in situ; Association between red fluorescence emitted by bacterial plaque and caries activity: in situ study

Bittar, Daniela Gonçalves
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 08/03/2012 Português
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O objetivo desse estudo in situ cruzado de duas fases foi avaliar a influência da presença de placa dentária fluorescente no vermelho na indução de lesões cariosas. Foram utilizados 272 blocos de esmalte bovino, que foram avaliados inicialmente em relação à microdureza superficial e quantificação da fluorescência verde com o QLF (Quantitative light-induced fluorescence). Dezessete voluntários utilizaram dispositivos palatais removíveis, com oito amostras cobertas com uma rede plástica para favorecer maior acúmulo de placa. No grupo experimental foi gotejada solução de sacarose a 20%, 8 X ao dia e no grupo controle, água destilada. Cada fase durou 14 dias com 7 dias de wash-out. Os blocos foram avaliados após 4, 7, 10 e 14 dias. Após cada período, a placa bacteriana presente sobre a superfície dos blocos foi analisada utilizando o QLF para a quantificação de fluorescência vermelha. Após cuidadosa limpeza da superfície, o bloco foi novamente avaliado para a perda de fluorescência verde (QLF) e perda de microdureza superficial. Foram realizadas análises de multinível para comparação entre os grupos, bem como análises de regressão linear de multinível entre as medidas de fluorescência vermelha e os desfechos relacionados à desmineralização. Em relação à microdureza de superfície...

Fluorescência dental: possível aplicação forense; Fluorescence dental: potential application in forensic science

Silva, Ricarda Duarte da
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 02/08/2012 Português
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Nos casos de identificação de ossadas, segmentos do esqueleto ou ossos isolados, buscar o diagnóstico dos dados biotipológicos, como a idade do indivíduo, proporciona a possibilidade de estabelecer uma conexão com suspeitos desaparecidos. Em dentes naturais a fluorescência ocorre em dentina e também em esmalte, embora este apresente menor índice de fluorescência. É sabido que o esmalte, a dentina e polpa sofrem mudanças notáveis durante a vida do indivíduo. O esmalte torna-se mais mineralizado, liso e fino, sofre desgaste fisiológico e patológico o que pode causar áreas de exposição da dentina que altera a expressão cromática do dente natural. A polpa diminui em volume devido à deposição de dentina secundária, assim a dentina torna-se espessa com o tempo. Sendo o esmalte e a dentina responsáveis pelo fenômeno de fluorescência dental e estes elementos dentários sofrem alteração significativa durante a vida, sugere-se avaliar tal fenômeno sob a luz da odontologia legal com vista a desenvolver um método para se estimar a idade de um indivíduo. O presente estudo tem por propósito verificar a existência de correlação entre idade e alteração da fluorescência em dentes in vivo. A amostra foi constituída por 66 brasileiros...

Espectroscopia de fluorescencia como metodo para monitoramento de porfiria induzida por dieta de glicose; Fluorescence spectroscopy as a method for diagnosis of porphyria induced by glucose diet of 5%

João Wagner Rodrigues Hernandez
Fonte: Biblioteca Digital da Unicamp Publicador: Biblioteca Digital da Unicamp
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 26/02/2009 Português
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A pesquisa de fluorescência nativa em tecidos biológicos tem despertado grande interesse na Biologia e Medicina. A fluorescência óptica tornou-se instrumento indispensável aos diagnósticos, sendo um método eficiente e não invasivo. Neste trabalho investigamos a presença de fluorescência nativa em áreas corpóreas de ratos Wistar, subdivididos em dois grupos: um com alimentação normal e outro com dieta de glicose 5%. Em áreas internas (experimento 1), não ficou evidenciada a fluorescência nativa em animais com alimentação normal de água e ração. Nos animais submetidos à dieta de glicose, observamos a presença de fluorescência nativa vermelha, captada por espectroscopia, alcançando um pico máximo de emissão luminosa em 120 horas de dieta e retomando valores iniciais, quando sua dieta voltou ao normal. O conteúdo do lúmen intestinal foi analisado espectroscopicamente e por prova bioquímica. O gráfico obtido foi semelhante ao da PpIX e o teste bioquímico (Eales modificado ) resultou positivo à presença de substância porfirínica. A fluorescência em áreas externas, bolsa escrotal, focinho, pata e cauda, também foi pesquisada nas mesmas condições de dieta (normal e glicosada), evidenciando que animais com dieta normal...

Chlorophyll fluorescence of the testa of Brassica oleracea seeds as an indicator of seed maturity and seed quality

Jalink,H.; Frandas,A.; Schoor,R. van der; Bino,J.B.
Fonte: São Paulo - Escola Superior de Agricultura "Luiz de Queiroz" Publicador: São Paulo - Escola Superior de Agricultura "Luiz de Queiroz"
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/1998 Português
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Chlorophyll fluorescence of the testa of seeds is proposed as a non-invasive method for the determination of maturity and quality of seeds. In this study cabbage seeds (Brassica oleracea) were sorted individually based on the chlorophyll fluorescence signals into four subsamples labeled with respect to their chlorophyll fluorescence signal (low, medium, high and very high). The results show that the magnitude of the chlorophyll fluorescence signal was inversely related to the quality of the seeds, expressed as germination %, normal seedling %, germination rate (T50) and uniformity of germination (T75-T25). The seed lot could be improved from 90 to 97% normal seedlings by sorting out 13% of the seeds with very high chlorophyll fluorescence signals. Advantages of the chlorophyll fluorescence method for sorting seeds are the high sensitivity, the method being fully non-destructive, the high speed at which the fluorescence is generated and measured and the specificity for only chlorophyll. Other pigments or substances which can influence seed colour but do not fluoresce at the specific wavelengths of excitation and emission of chlorophyll, will not contribute to the fluorescence signal. These characteristics make chlorophyll fluorescence highly suitable as a new sorting technique.

Multiphoton fluorescence recovery after photobleaching : advancements for novel in vivo applications

Sullivan, Kelley Diane (1978 - ); Brown, Edward B.
Fonte: University of Rochester Publicador: University of Rochester
Tipo: Tese de Doutorado Formato: Number of Pages:xviii, 137 leaves
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Thesis (Ph. D.)--University of Rochester. Dept. of Physics and Astronomy, 2010.; Multiphoton fluorescence recovery after photobleaching (MP-FRAP) is a laser microscopy technique used to probe the transport properties of macromolecules in biological systems. MP-FRAP utilizes two-photon fluorescence and photobleaching to produce a three-dimensionally resolved diffusion coefficient for an ensemble of molecules in the region of the two-photon focal volume. This thesis describes two fundamental improvements to the MP-FRAP technique, which are vital steps to enable MP-FRAP to be applied to the complex in vivo environment. In Chapter 1, we lay the groundwork for our discussion of these advancements by introducing the MP-FRAP technique and the physics upon which it is based. We begin with a description of fluorescence and diffusion and discuss their importance in biomedical research. Next, we describe how two-photon fluorescence and photobleaching are applied to a diffusing system to measure the diffusion coefficient via fluorescence recovery after photobleaching (FRAP). Then, we take the reader through the evolution of FRAP, which leads to the application of twophoton fluorescence and photobleaching to produce MP-FRAP. Along the way...

Interaction of aza-aromatic compounds with porous silica beads and controlled porous glasses as studied by absorption and fluorescence spectroscopy; Absorptions- und fluoreszenzspektroskopische Untersuchungen der Wechselwirkung von Aza-aromaten mit porösen Kieselgelen und kontrolliert porösen Gläsern

Elsherbiny, Abeer
Fonte: Universidade de Tubinga Publicador: Universidade de Tubinga
Tipo: Dissertação
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In this work, a comparative study of the surface acidities of different micro-porous solid media based on silicon dioxide (non-modified silica beads, silica beads modified with C30 alkyl chains, silica modified with polymers, and controlled porous glasses) is presented. For this purpose, conjugated molecules with additional electron-donor and proton-acceptor centres are used as adsorbates. Acridine (AC) and some of its derivatives 1,2,7,8-dibenzacridine (1-DBA), 3,4,5,6-dibenzacridine (3-DBA), and acridine orange (AO) are chosen for this study. The absorption and fluorescence spectra of the probe molecules in solution are used to compare with the spectra of the adsorbed species, and to distinguish between various surface binding sites of different acidity. The mobilities of the adsorbed probe molecules on the surfaces are determined by the fluorescence anisotropy. The kinetics of the adsorption of the probes at the surfaces are measured by time-dependent absorbance and fluorescence spectroscopy. The accessibility of the adsorbed species at the surfaces to oxygen and the reaction with active groups on chemically modified silica surfaces (mainly amino groups) are also studied by fluorescence spectroscopy. In the case porous Vycor glass surface as adsorbent and acridine as adsorbate...

Étude de l'oligomérisation et de la fonction de canaux ioniques par spectroscopie de fluorescence et fluorométrie en voltage imposé

McGuire, Hugo
Fonte: Université de Montréal Publicador: Université de Montréal
Tipo: Thèse ou Mémoire numérique / Electronic Thesis or Dissertation
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La fonction des canaux ioniques est finement régulée par des changements structuraux de sites clés contrôlant l’ouverture du pore. Ces modulations structurales découlent de l’interaction du canal avec l’environnement local, puisque certains domaines peuvent être suffisamment sensibles à des propriétés physico-chimiques spécifiques. Les mouvements engendrés dans la structure sont notamment perceptibles fonctionnellement lorsque le canal ouvre un passage à certains ions, générant ainsi un courant ionique mesurable selon le potentiel électrochimique. Une description détaillée de ces relations structure-fonction est cependant difficile à obtenir à partir de mesures sur des ensembles de canaux identiques, puisque les fluctuations et les distributions de différentes propriétés individuelles demeurent cachées dans une moyenne. Pour distinguer ces propriétés, des mesures à l’échelle de la molécule unique sont nécessaires. Le but principal de la présente thèse est d’étudier la structure et les mécanismes moléculaires de canaux ioniques par mesures de spectroscopie de fluorescence à l’échelle de la molécule unique. Les études sont particulièrement dirigées vers le développement de nouvelles méthodes ou leur amélioration. Une classe de toxine formeuse de pores a servi de premier modèle d’étude. La fluorescence à l’échelle de la molécule unique a aussi été utilisée pour l’étude d’un récepteur glutamate...

FluorMODgui: A Graphic User Interface for the Spectral Simulation of Leaf and Canopy Fluorescence Effects

Zarco-Tejada, Pablo J.; Miller, J. R.; Pedrós, R.; Verhoef, W.; Berger, M.
Fonte: Conselho Superior de Investigações Científicas Publicador: Conselho Superior de Investigações Científicas
Tipo: Comunicación de congreso Formato: 180838 bytes; application/pdf
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2nd International Workshop on Remote Sensing of Vegetation Fluorescence, 17-19 Nov. 2004, Montreal, Canada; This paper reports on the status of the FluorMODgui, a Graphic User Interface (GUI) software package developed within the frame of the FluorMOD project "Development of a Vegetation Fluorescence Canopy Model". The study was launched in 2002 by the European Space Agency to advance the science of vegetation fluorescence simulation through the development and integration of leaf and canopy fluorescence models based on physical methods. The FluorMODgui enables simulation of leaf and canopy reflectance with the effects of chlorophyll fluorescence, running the leaf and canopy models (dubbed FluorMODleaf and FluorSAIL) independently, as well as through a coupling scheme. Inputs for the FluoMODleaf layer are N (number of leaf layers, as in PROSPECT), Cab (chlorophyll a+b content), Cw (water equivalent thickness), Cm (dry matter content), Fi (fluorescence quantum efficiency), T (temperature), S (species type), and Sto (stoichiometry). Inputs for the FluorSAIL canopy layer are: a MODTRAN4 6-parameter spectra, a soil reflectance spectra, leaf reflectance & transmittance spectra, a excitation-fluorescence response matrix (back & forward)...

Chlorophyll Fluorescence Detection with a High-Spectral Resolution Spectrometer through in-filling of the O2-A band as function of Water Stress in Olive Trees

Zarco-Tejada, Pablo J.; Pérez-Priego, O.; Sepulcre-Cantó, G.; Miller, J. R.; Fereres Castiel, Elías
Fonte: Conselho Superior de Investigações Científicas Publicador: Conselho Superior de Investigações Científicas
Tipo: Comunicación de congreso Formato: 685368 bytes; application/pdf
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2nd International Workshop on Remote Sensing of Vegetation Fluorescence, 17-19 Nov. 2004, Montreal, Canada; A high spectral resolution spectrometer of 0.065 nm FWHM in the 680-770 nm range was used for collecting spectral measurements in an orchard of olive trees in Spain under 3 different water stress treatments. The measurements were conducted as part of validation efforts for the FluorMOD project funded by the European Space Agency (ESA) to advance the science of vegetation fluorescence simulation. Diurnal steadystate chlorophyll fluorescence was measured from leaves in the field during summer 2004 using the PAM-2100 fluorometer to study the effects of water stress on chlorophyll fluorescence. Water potential, photosynthesis, and stomatal conductance on trees were also measured in a weekly basis to track the effects of water stress on the tree status and functioning. Infrared Apogee sensors were placed on top of the trees for diurnal thermal data collection, studying the effects of water stress on the tree temperature as an indicator of stress. The Ocean Optics HR-2000 spectrometer was used to measure irradiance and radiance spectra from above tree crowns under different stress conditions. The spectral measurements of irradiance with a cosine corrector and crown radiance with bare fibre were acquired from a pole 7 m in height to collect nadir radiance from the top of tree crowns. Analysis in the red edge covering the 680-770 nm range enabled the study of the chlorophyll fluorescence in-filling in the O2-A band at 760 nm. Results of the spectral analysis and simulation using the FluorMOD radiative transfer model demonstrate that water stress effects on steady-state fluorescence are detectable at the tree level in the O2-A band from reflectance spectra due to the in-filling effects.; The development of the FluorMODgui interface has been carried out in the frame of the ESA-project Development of a Vegetation Fluorescence Canopy Model...

Progress on the development of an integrated canopy fluorescence model

Miller, J. R.; Berger, M.; Alonso, L.; Cerovic, Z.; Goulas, Y.; Jacquemoud, S.; Louis, J.; Mohammed, G. H.; Moya, I.; Pedrós, R.; Moreno, J.; Verhoef, W.; Zarco-Tejada, Pablo J.
Fonte: Conselho Superior de Investigações Científicas Publicador: Conselho Superior de Investigações Científicas
Tipo: Comunicación de congreso Formato: 123134 bytes; application/pdf
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2003 - International Geoscience and Remote Sensing Symposium, IGARSS'03, pp. 601-603 Vol.1, Toulouse (France), 21-25/7/2004; Typical environmental plant stress factors are excess of light, deficiencies of water and nutrients, temperature extremes, diseases, pests and pollutants. An early indicator for vegetation status and vitality by means of remote sensing would therefore serve a range of applications such as renewable resource management and precision farming. Vegetation fluorescence is a direct indicator for plant physiology, and could therefore be used as an early indicator for vegetation health status and vitality. Vegetation chlorophyll fluorescence is a function of photochemical processes and efficiency, which are directly linked to primary productivity and CO2 flux from the atmosphere, and could therefore also provide a means to assess the terrestrial carbon cycle. A study was launched in October 2002 by the European Space Agency to advance the underlying science of a possible future vegetation fluorescence space mission by addressing the need for an integrated canopy fluorescence model. The objective of this study is to review and advance existing fluorescence models at the leaf level and to integrate these into canopy models in order to simulate the combined spectral reflected radiance and passive fluorescence emission signals. This model is to be validated with new and existing field campaign measurements. This paper reports on the status of this project. The input radiometric and photosynthetic variables have been selected to define the vegetation fluorescence signal consisting of far-red and red chlorophyll fluorescence as spectral emission features...

FluorMODgui V3.0: A graphic user interface for the spectral simulation of leaf and canopy chlorophyll fluorescence

Zarco-Tejada, Pablo J.; Miller, J. R.; Pedrós, R.; Verhoef, W.; Berger, M.
Fonte: Elsevier Publicador: Elsevier
Tipo: Artículo Formato: 4085 bytes; image/gif
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The FluorMODgui Graphic User Interface (GUI) software package developed within the frame of the FluorMOD project Development of a Vegetation Fluorescence Canopy Model is presented in this manuscript. The FluorMOD project was launched in 2002 by the European Space Agency (ESA) to advance the science of vegetation fluorescence simulation through the development and integration of leaf and canopy fluorescence models based on physical methods. The design of airborne or space missions dedicated to the measurement of solar-induced chlorophyll fluorescence using remote-sensing instruments require physical methods for quantitative feasibility analysis and sensor specification studies. The FluorMODgui model developed as part of this project is designed to simulate the effects of chlorophyll fluorescence at leaf and canopy levels using atmospheric inputs, running the leaf model, FluorMODleaf, and the canopy model, FluorSAIL, independently, through a coupling scheme, and by a multiple iteration protocol to simulate changes in the viewing geometry and atmospheric characteristics. Inputs for the FluorMODleaf model are the number of leaf layers, chlorophyll a+b content, water equivalent thickness, dry matter content, fluorescence quantum efficiency...

Detection of Water Stress in Orchard Trees with a High-Resolution Spectrometer through Chlorophyll Fluorescence in-filling of the O2-A band

Pérez-Priego, O.; Zarco-Tejada, Pablo J.; Miller, J. R.; Sepulcre-Cantó, G.; Fereres Castiel, Elías
Fonte: Institute of Electrical and Electronics Engineers Publicador: Institute of Electrical and Electronics Engineers
Tipo: Artículo Formato: 4085 bytes; image/gif
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A high spectral resolution spectrometer with 0.065-nm full-width half-maximum was used for collecting spectral measurements in an orchard field under three water stress treatments. The study was part of the FluorMOD project funded by the European Space Agency to develop a leaf-canopy reflectance model to simulate the effects of fluorescence. Water deficit protocols generated a gradient in solar-induced chlorophyll fluorescence emission and tree physiological measures. Diurnal steady-state chlorophyll fluorescence was measured from leaves in the field between June and November 2004 using the PAM-2100 fluorometer to study the effects of water stress on chlorophyll fluorescence. Spectral measurements of downwelling irradiance and upwelling crown radiance were conducted with the narrow-band spectrometer, enabling the canopy reflectance to be obtained at subnanometer spectral resolution and permitting the evaluation of the fluorescence in-filling effects on reflectance in trees under water stress conditions. Diurnal and seasonal measurements showed consistently lower steady-state fluorescence (Ft) and quantum yield F Fm in water-stressed trees, yielding mean values of Ft = 038 (well-irrigated) and Ft = 0 21 (water-stressed trees). The agreement between Ft and water potential showed that steady-state fluorescence could be used to detect differences in water stress levels...

Imaging chlorophyll fluorescence with an airborne narrow-band multispectral camera for vegetation stress detection

Zarco-Tejada, Pablo J.; Berni, José A. J.; Suárez, Lola; Sepulcre-Cantó, G.; Morales Iribas, Fermín; Miller, J. R.
Fonte: Elsevier Publicador: Elsevier
Tipo: Artículo Formato: 131118 bytes; application/pdf
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14 pages, 15 figures, 2 tables.-- Printed version published Jun 15, 2009.; Progress in assessing the feasibility for imaging fluorescence using the O2-A band with 1 nm full-width half-maximum (FWHM) bands centered at 757.5 and 760.5 nm is reported in this paper. Multispectral airborne data was acquired at 150 m above ground level in the thermal, visible and near infrared regions yielding imagery at 15 cm spatial resolution. Simultaneous field experiments conducted in olive, peach, and orange orchards (water stress trials), and an olive orchard (variety trial) enabled the detected variability in fluorescence emission to be examined as function of stress status. In a parallel modelling activity the coupled leaf–canopy reflectance–fluorescence model, FluorMOD, was used to assess fluorescence retrieval capability by the in-filling method, as well as by fluorescence indices from the published literature. Fluorescence retrievals using the in-filling method, the derivative index D702/D680 and reflectance indices R690/R630, R761–R757, and R761/R757 yielded the best results in the simulation study, while demonstrating insensitivity to leaf area index (LAI) variation. The fluorescence in-filling method, derivative index D702/D680, and R761–R757 were the indices least affected by chlorophyll a + b (Cab) variation. On the other hand...

Ultraviolet-induced fluorescence for plant monitoring: present state and prospects

Cerović, Zoran G.; Samson, Guy; Morales Iribas, Fermín; Tremblay, Nicolas; Moya, Ismaël
Fonte: EDP Sciences Publicador: EDP Sciences
Tipo: Artículo Formato: 4550412 bytes; application/pdf
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[EN] UV excitation of green leaves induces two distinct, fundamentally different, but still complementary types of fluorescence: a blue-green fluorescence in the 400-630 nm range and the chlorophyll a fluorescence in the red to far-red region (630-800 nm) of the spectrum. The relative intensities of these two types of fluorescence are highly sensitive to intrinsic leaf properties and environmental factors. Therefore, fluorescence emission spectra induced by UV radiation can be considered as a complex fluorescence signature that can reveal much about the physiological state of the plant. UV-induced fluorescence of leaves provides us with information on photosynthesis, primary photochemical reactions and chlorophyll content, and also on the presence and accumulation of the product of the secondary metabolism and the redox state of the cell. In this review we pay particular attention to the present and potential application of these signals to active remote sensing of vegetation, i.e. fluorosensing.; [FR] Fluorescence induite par le rayonnement ultraviolet pour le suivi de la végétation : état actuel et perspectives. L'excitation de feuilles vertes dans l'ultraviolet induit deux types de fluorescence distinctes, fondamentalement différentes...

Chlorophyll Fluorescence effects on Vegetation Apparent Reflectance: I. Leaf-level Measurements and Model Simulation

Zarco-Tejada, Pablo J.; Miller, J. R.; Mohammed, G. H.; Noland, T. L.
Fonte: Elsevier Publicador: Elsevier
Tipo: Artículo Formato: 4085 bytes; image/gif
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Results from a series of laboratory measurements of spectral reflectance and transmittance of individual leaves and from a modeling study are presented which demonstrate that effects of natural chlorophyll fluorescence (CF) are observable in the red edge spectral region. Measurements have been made with a Li-Cor Model 1800 integrating sphere apparatus coupled to an Ocean Optics Model ST1000 fiber spectrometer in which the same leaves are illuminated alternately with and without fluorescence-exciting radiation in order to separate the fluorescence emission component from the reflectance spectrum. The resulting difference spectrum is shown experimentally to be consistent with a fluorescence signature imposed on the inherent leaf reflectance signature. A study of the diurnal change in leaf reflectance spectra, combined with fluorescence measurements with the PAM-2000 Fluorometer, show that the difference spectra are consistent with observed diurnal changes in steady-state fluorescence. In addition, the time decay in the difference signature from repetitive leaf spectral reflectance measurements is seen to be consistent with the time decay of the leaf fluorescence signal (Kautsky effect) of dark-adapted leaves. The expected effects of chlorophyll fluorescence emission on the apparent spectral reflectance from a single leaf are also simulated theoretically using the doubling radiative transfer method. These modeling results demonstrate that the laboratory observations of a difference spectrum with broad peak at about 750 nm and a much smaller peak near 690 nm are in agreement with theory. Model simulation shows that chlorophyll pigment and fluorescence each affect indices that are being used in optical remote sensing to characterize pigment levels and stress in vegetation canopies. Implications for high spectral resolution remote sensing of forest canopies are presented in a companion paper.; Peer reviewed

Chlorophyll Fluorescence effects on Vegetation Apparent Reflectance: II. Laboratory and Airborne Canopy-Level Measurements with Hyperspectral Data

Zarco-Tejada, Pablo J.; Miller, J. R.; Mohammed, G. H.; Noland, T. L.; Sampson, P. H.
Fonte: Elsevier Publicador: Elsevier
Tipo: Artículo Formato: 4085 bytes; image/gif
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Relationships found between Compact Airborne Spectrographic Imager (CASI) hyperspectral canopy reflectance measurements at laboratory and field levels with PAM-2000 chlorophyll fluorescence data are presented. This is a continuation of the paper where relationships at the leaf level between leaf reflectance and chlorophyll fluorescence were found and demonstrated to be consistent with theory using the Fluorescence-Reflectance-Transmittance (FRT) model. Experiments using the hyperspectral CASI sensor in the laboratory to observe a canopy of maple seedlings are performed as an intermediate step to demonstrate the link between the results at leaf-level and the CASI field canopy levels. Scene observations of the seedlings utilizing a long-pass blocking filter showed that apparent canopy reflectance in the laboratory is affected by changes in fluorescence emissions. A laboratory experiment on seedlings subjected to diurnally induced change shows the strong link between CASI canopy reflectance optical indices in the 680–690-nm region and Fv/Fm dark-adapted chlorophyll fluorescence. Stressed and healthy maple seedlings are used to demonstrate the use of optical indices calculated from the 680–690-nm spectral region to track changes in steady-state fluorescence: the curvature index R6832/(R675·R691) and the R685/R655 ratio calculated from the canopy reflectance are related to leaf-measured Ft...

Laser-induced fluorescence: Limits to the remote detection of hydrogen ion, aluminum, and dissolved organic matter

Philpot, William; Vodacek, Anthony
Fonte: Elsevier Science B.V., Amsterdam Publicador: Elsevier Science B.V., Amsterdam
Tipo: Artigo de Revista Científica
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Laser-induced fluorescence (LIF) of dissolved organic matter (DOM) in lake water is, to a certain extent, indicative of water quality. DOM fluorescence intensity varies directly with connentration of the fluorescing organic matter; however, the intensity and spectral distribution of fluorescence are also affected by other physical and chemical factors. The chemical factors include concentrations of trace metals, hydrogen ion, and the composition of the DOM itself. An empirical study was conducted seeking specific relationships between the intensity and spectral distribution of DOM fluorescence and the concentration of aluminum and hydrogen ion in lake water. Water samples from 49 lakes in northern Michigan and northern Wisconsin were collected and their fluorescence emission spectra analyzed with respect to the lake water chemistry. Trends that had been apparent in previous measurements using prepared samples were less visible in the lake water data. Observed changes in the fluorescence emission can be produced by one of two general mechanisms: quenching and precipitation. Quenching of DOM fluorescence - a result of cation reactions - is seen as a reduction of the total fluorescence intensity and a shift of the overall emission spectrum to shorter wavelengths. In contrast...

Photoinhibitory printing on leaves, visualized by chlorophyll fluorescence imaging and confocal microscopy, is due to diminished fluorescence from grana

Osmond, C Barry; Schwartz, Owen; Gunning, Brian
Fonte: CSLI Publications Publicador: CSLI Publications
Tipo: Artigo de Revista Científica
Português
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346.87805%
By analogy with the starch printing technique, it was hypothesised that photoinhibition could be used to print images on leaves that would be invisible to the eye, but easily revealed by chlorophyll fluorescence imaging. We first illustrate the process of chlorophyll fluorescence printing on leaves of the shade plant, Cissus rhombifolia, using photographs of artefacts from starch printing experiments in the laboratory of Molisch. We then use portraits of current leaders in chlorophyll fluorescence research to demonstrate the stability of these images in living tissues. Text printing from microfilm of Ewart's pioneering studies in photoinhibition shows the resolution of the method with the fixed-focus, portable, imaging system used here. The stability of images, as well as quenching analysis of images and of leaves, suggests that localised photoinactivation, rather than sustained photoprotection, is responsible for the detail displayed by fluorescence printing. Electron micrograph positives of stained thylakoids can be printed to create an illusion of what is imagined to be the source of chlorophyll fluorescence at the membrane level. Individual chloroplasts in adjacent cells under the grid pattern of granal stacks printed on leaves were also examined using a confocal microscope. Compared with chloroplasts in the shaded parts of the grid...