Search results for "Fluorescence"
showing 10 items of 2463 documents
An Off-On-Off Fluorescent Sensor for pH Windows Based on the 13aneN4-Zn 2+ System
2016
International audience; The new ligand L was prepared and features a 13-membered tetraaza macrocyclic ring with a 1,8-naphthalimide fluorophore appended to a C atom of its backbone. The protonation constants of L as well as its complexation constants with Zn2+ ions were determined in 1:1 water/methanol solutions by potentiometric titrations. Fluorimetric pH titrations were performed with L alone and L in the presence of Zn2+ ions (1:1), and the species distributions (%) versus pH were compared. A window-shaped fluorescence trend was observed with pH for the L/Zn2+ system, which behaves as an off-on-off pH sensor. The on window is centred in the 6.5-7.5 pH range, in correspondence with the f…
Domain formation in monolayers
1995
For phospholipids at the air/water interface we demonstrate that molecular chirality in some, but not in all, cases influences the domain shapes. In other cases chirality in the head group region can cause a chiral structure considering the tail arrangement. This indicates head group ordering. Minute changes of the molecular structure may change domain morphology from circular to dendritic. This can be related to slight changes of the lattice structure. In case of a dendritic domain the chains are more tilted, the deviation from hexagonal symmetry is more pronounced, and hence the lattice anisotropy is larger. This can be understood also in view of recent simulations considering diffusion-l…
IP 3 signalling regulates exogenous RNA i in C aenorhabditis elegans
2015
RNA interference (RNAi) is a widespread and widely exploited phenomenon. Here, we show that changing inositol 1,4,5-trisphosphate (IP3) signalling alters RNAi sensitivity in Caenorhabditis elegans. Reducing IP3 signalling enhances sensitivity to RNAi in a broad range of genes and tissues. Conversely up-regulating IP3 signalling decreases sensitivity. Tissue-specific rescue experiments suggest IP3 functions in the intestine. We also exploit IP3 signalling mutants to further enhance the sensitivity of RNAi hypersensitive strains. These results demonstrate that conserved cell signalling pathways can modify RNAi responses, implying that RNAi responses may be influenced by an animal's physiology…
Facile Synthesis of Fluorescent Polymer Nanoparticles by Covalent Modification-Nanoprecipitation of Amine-Reactive Ester Polymers
2015
Emission wavelength control in fluorescent nanoparticles (NPs) is crucial for their applications. In the case of inorganic quantum dots or dye-impregnated silica NPs, such a control is readily achieved by changing the size of the particles or choosing appropriate fluorescent dyes, respectively. A similar modular approach for controlling the emission wavelength of fluo-rescent polymer NPs, however, is difficult. This article reports on fluorescent polymer NPs, the synthesis of which provides a platform for a modular approach towards the preparation of fluorescent NPs of desired emission wavelength. Atom-transfer radical polymerization (ATRP) is employed to synthesize reactive ester polymers,…
Study of the role of sulfur functionalities in humic acids for uranium(VI) complexation
2009
Humic substances influence the speciation and migration behavior of toxic and radiotoxic metal ions, such as actinides, in the environment. Depending on their origin, humic substances contain different amounts of sulfur ranging from 0.1 to 3.6% and 0.5 to 1.43% in soil and aquatic humic substances, respectively [1]. Reduced, intermediately oxidized and highly oxidized sulfur functionalities occur in humic substances [1]. Although sulfur functionalities occur in small concentrations, they can play an important role in the complexation of selected metal ions. Knowledge about the impact of sulfur functionalities on the metal ion complexation by humic substances and their significance compared …
<title>Compact multi-functional skin spectrometry set-up</title>
2006
A portable fibre-optic spectrometry set-up has been assembled and tested for applications in skin diffuse reflectance spectrometry, laser fluorescence spectrometry and multi-wavelength reflection photoplethysmography (multi-PPG) studies. The spectrometry set was tested by diffuse reflectance and fluorescence measurements for diagnostics of skin vascular malformations and pigmented diseases such as nevi and melanoma . In addition, studies of microcirculation in blood vessels located at different depths from the skin surface were performed by the multi-PPG method. The results of skin diffuse reflectance and autofluorescence showed differences in spectra of healthy and pathologic skin. The par…
Measurement of the Fluctuations in the Number of Muons in Extensive Air Showers with the Pierre Auger Observatory
2021
The successful installation, commissioning, and operation of the Pierre Auger Observatory would not have been possible without the strong commitment and effort from the technical and administrative staff in Malargue. We are very grateful to the following agencies and organizations for financial support: Argentina-Comision Nacional de Energia Atomica, Agencia Nacional de Promocion Cientifica y Tecnologica (ANPCyT), Consejo Nacional de Investigaciones Cientificas y Tecnicas (CONICET), Gobierno de la Provincia de Mendoza, Municipalidad de Malargue, NDM Holdings and Valle Las Lenas; in gratitude for their continuing cooperation over land access; Australia-the Australian Research Council; Brazil…
Research data supporting 'Short hydrogen bonds enhance nonaromatic protein-related fluorescence'
2021
Raw data for experimental figures. Files contain .cif (crystallographic information file) for XRD data of the L-pyro-amm structure. .xlsx file containing spectra for absorption of L-glutamine, L-pyroglutamine and L-pyro-amm. .xlsx file contains spectra for fluorescence excitation and emission collected over 8 days for L-glutamine conversion to L-pyro-amm.
Ligand-Centred Fluorescence and Electronic Relaxation Cascade at Vibrational Time Scales in Transition-Metal Complexes
2015
Using femtosecond-resolved photoluminescence up-conversion, we report the observation of the fluorescence of the high-lying ligand-centered (LC) electronic state upon 266 nm excitation of an iridium complex, Ir(ppy)(3), with a lifetime of 70 +/- 10 fs. It is accompanied by a simultaneous emission of all lower-lying electronic states, except the lowest triplet metal-to-ligand charge-transfer ((MLCT)-M-3) state that shows a rise on the same time scale. Thus, we observe the departure, the intermediate steps, and the arrival of the relaxation cascade spanning similar to 1.6 eV from the (LC)-L-1 state to the lowest 3MLCT state, which then yields the long-lived luminescence of the molecule. This …
Briofītu inducētās izturības pētījumi ar hlorofila a fluorescences analīzes metodi
2015
Darbā aprakstīti briofītu pielāgošanās mehānismi sarežģītiem dzīves apstākļiem. Mērķis bija noskaidrot, vai nepārtrauktā hlorofila a fluorescence ir izmantojama, lai noteiktu briofītu inducēto izturību. Pētījums sastāv no divām daļām. Lai noteiktu briofītu izžūšanas izturību un iespēju izmantot hlorofila a fluorescences metodi tās novērtēšanai, ievāktas trīs sugas, kurām veikta fluorescences analīze paraugu izžūšanas laikā. Lai noteiktu briofītu fluorescences rādītājus briofītiem dažādās temperatūrās, ievāktas 4 sugas. Darbā secināts, ka nepārtraukto hlorofila a fluorescenci ir iespējams izmantot, lai noteiktu briofītu inducēto izturību. Iegūtie fluorescences dati norāda uz izmaiņām briofīt…