About: Fluorescence spectrometry is a research topic. Over the lifetime, 16244 publications have been published within this topic receiving 565365 citations.
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TL;DR: Aromatic carbon and the presence of specific aromatic compounds resulted in EEMs that aided in differentiating wastewater effluent DOM from drinking water DOM, and the highest cumulative EEM volume was observed for hydrophobic neutral DOM fractions.
Abstract: Excitation−emission matrix (EEM) fluorescence spectroscopy has been widely used to characterize dissolved organic matter (DOM) in water and soil. However, interpreting the >10,000 wavelength-dependent fluorescence intensity data points represented in EEMs has posed a significant challenge. Fluorescence regional integration, a quantitative technique that integrates the volume beneath an EEM, was developed to analyze EEMs. EEMs were delineated into five excitation−emission regions based on fluorescence of model compounds, DOM fractions, and marine waters or freshwaters. Volumetric integration under the EEM within each region, normalized to the projected excitation−emission area within that region and dissolved organic carbon concentration, resulted in a normalized region-specific EEM volume (Φi,n). Solid-state carbon nuclear magnetic resonance (13C NMR), Fourier transform infrared (FTIR) analysis, ultraviolet−visible absorption spectra, and EEMs were obtained for standard Suwannee River fulvic acid and 15 h...
TL;DR: New fluorescent indicators for Ca2+ that are genetically encoded without cofactors and are targetable to specific intracellular locations are constructed and dubbed ‘cameleons’.
Abstract: Important Ca2+ signals in the cytosol and organelles are often extremely localized and hard to measure. To overcome this problem we have constructed new fluorescent indicators for Ca2+ that are genetically encoded without cofactors and are targetable to specific intracellular locations. We have dubbed these fluorescent indicators 'cameleons'. They consist of tandem fusions of a blue- or cyan-emitting mutant of the green fluorescent protein (GFP), calmodulin, the calmodulin-binding peptide M13, and an enhanced green- or yellow-emitting GFP. Binding of Ca2+ makes calmodulin wrap around the M13 domain, increasing the fluorescence resonance energy transfer (FRET) between the flanking GFPs. Calmodulin mutations can tune the Ca2+ affinities to measure free Ca2+ concentrations in the range 10(-8) to 10(-2) M. We have visualized free Ca2+ dynamics in the cytosol, nucleus and endoplasmic reticulum of single HeLa cells transfected with complementary DNAs encoding chimaeras bearing appropriate localization signals. Ca2+ concentration in the endoplasmic reticulum of individual cells ranged from 60 to 400 microM at rest, and 1 to 50 microM after Ca2+ mobilization. FRET is also an indicator of the reversible intermolecular association of cyan-GFP-labelled calmodulin with yellow-GFP-labelled M13. Thus FRET between GFP mutants can monitor localized Ca2+ signals and protein heterodimerization in individual live cells.
TL;DR: The progress in applying single-molecule detection and single-Molecule spectroscopy at room temperature by laser-induced fluorescence with the use of fluorophores that are site-specifically attached to macromolecules is reviewed.
Abstract: Recent advances in single-molecule detection and single-molecule spectroscopy at room temperature by laser-induced fluorescence offer new tools for the study of individual macromolecules under physiological conditions. These tools relay conformational states, conformational dynamics, and activity of single biological molecules to physical observables, unmasked by ensemble averaging. Distributions and time trajectories of these observables can therefore be measured during a reaction without the impossible need to synchronize all the molecules in the ensemble. The progress in applying these tools to biological studies with the use of fluorophores that are site-specifically attached to macromolecules is reviewed.
TL;DR: In this article, the concentration du copolymere de la variation des proprietes spectroscopiques du pyrene provoquee par son partage entre les phases micellaires et aqueuses permet de determiner les concentrations of critiques micellaire and les coefficients de partage.
Abstract: L'etude en fonction de la concentration du copolymere de la variation des proprietes spectroscopiques du pyrene provoquee par son partage entre les phases micellaires et aqueuses permet de determiner les concentrations critiques micellaires et les coefficients de partage
TL;DR: A fluorometric method is presented that gives precise measurements of ammonium over a wide range of concentrations and salinities emphasizing submicromolar levels and not only solves analytical problems but also substantially simplifies sample collection and preservation.
Abstract: The accurate measurement of ammonium concentrations is fundamental to understanding nitrogen biogeochemistry in aquatic ecosystems. Unfortunately, the commonly used indophenol blue method often yie...
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