Search results for "DYES"

Warm white LEDs based on Lumogen® Red and Yellow

2013

One of the most widespread solutions for the production of white LEDs is the frequency downconversion of a part of the light, coming from a blue source, by exciting one or more materials (typically Ce:YAG) that emit at longer wavelength [1]. In this work we report ona simple and less expensive method to fabricate warmwhite-light LEDsusingthe photoluminescence of Lumogen®, a perylene-based polymer dyecommercialized by BASF,that has already beenprovedto be a good substitute for conventi onal inorganic colour conversion [2],[3]. Standard InGaN-based blue LEDs (~ 450 nm) were fabricated on a sapphire substrate by metal organic chemical vapour deposition. Both Lumogen® Yellow, and Red dyes wered…

Warm white LED light by frequency down-conversion of mixed yellow and red Lumogen®

2013

This work reports on the benefits and promising opportunities offered by white LED hybrid technology, based on a mixing perylene-based dyes in order to obtain a warm white light for frequency-down conversion. In a standard Ce:YAG-based white LED, the white light appears cold due to the weakness of red wavelength components in the emission spectrum. In order to obtain a warmer white, one possible solution is to add a red phosphor to the yellow one to move the chromatic coordinates properly, though the luminous efficiency drastically decreases due to the increased light absorption of the coating layer. It is generally believed that the low efficiency of warm white LEDs is the main issue today…

White LED light obtained by frequency down-conversion of perylene-based dyes

2012

Cytofluorometric detection of wine lactic acid bacteria: application of malolactic fermentation to the monitoring

2012

Abstract In this study we report for the first time a rapid, efficient and cost-effective method for the enumeration of lactic acid bacteria (LAB) in wine. Indeed, up to now, detection of LAB in wine, especially red wine, was not possible. Wines contain debris that cannot be separated from bacteria using flow cytometry (FCM). Furthermore, the dyes tested in previous reports did not allow an efficient staining of bacteria. Using FCM and a combination of BOX/PI dyes, we were able to count bacteria in wines. The study was performed in wine inoculated with Oenococcus oeni (106 CFU ml−1) stained with either FDA or BOX/PI and analyzed by FCM during the malolactic fermentation (MLF). The analysis …

Synthesis of new asymmetric xanthene dyes via catalyst-free SNAr with sulfur nucleophiles

2014

Addition of a single functional handle to the tricyclic moiety of fluorescein results in asymmetric xanthene dyes. Our synthesis of a new class of asymmetric xanthenes proceeds via an unusual SNAr with sulfur nucleophiles on electron rich aromatic xanthenes scaffolds in the absence of a metal catalyst. The resulting 3'-thioethers exhibit high photostability and are conveniently converted into reactive dyes for macromolecule labelling.

Straightforward access to water-soluble unsymmetrical sulfoxanthene dyes: application to the preparation of far-red fluorescent dyes with large stoke…

2014

An efficient synthesis of water-soluble unsymmetrical sulforhodamine/sulforhodol fluorophores containing a single julolidine fragment is presented. Owing to their valuable spectral properties in aqueous buffers, these dyes, especially those bearing a free aniline or phenol moiety, are valuable components of fluorogenic probes for a variety of biosensing applications. A further extension of this synthetic methodology to unusual phenols, namely 7-N,N-dialkylamino-4-hydroxy coumarins has enabled us to provide a new family water-soluble dyes of large Stokes’ shift with far-red spectral features.

Analysis of fluorescent MRI contrast agent behavior in the liver and thoracic aorta of mice.

2004

To characterize the behavior of magnetofluorescent products injected in mice intravenously.The magnetic resonance imaging (MRI) products were labelled with fluorescent molecules to examine the biodistribution process in vivo and observe them at the cellular level by means of confocal microscopy. Three-dimensional (3D) sequences of images were obtained by spectral analysis of sample preparations in a multiphoton confocal microscope and analyzed by the factor analysis of medical image sequence algorithm, which provides factor curves. Factor images are the result of image-processing methods that utilize information from emission spectra. Preparations are also screened in the counting mode to p…

Modular Assembly of Multimodal Imaging Agents through an Inverse Electron Demand Diels–Alder Reaction

2019

International audience; The combination of two imaging probes on a same biomolecule gives access to targeted bimodal imaging agents that can provide more accurate diagnosis, complementary information, or that may be used in different applications, such as PET imaging and fluorescence imagingassisted surgery. In this study, we demonstrate that dichlorotetrazine, a small, commercially available compound, can be used as a modular platform to easily assemble various imaging probes. Doubly-labeled tetrazines can then be conjugated to a protein through a biorthogonal IEDDA reaction. A series of difunctionalized tetrazine compounds containing various chelating agents and fluorescent dyes was synth…

Domowe sposoby farbowania włosów z wykorzystaniem surowców roślinnych

2022

Koloryzacja roślinna jest naturalną metodą farbowania włosów, która pozwala na uzyskanie różnych barw oraz dodatkowo pielęgnuje skórę głowy i włosy. Celem pracy było przybliżenie wiedzy na temat dostępnych metod farbowania z wykorzystaniem surowców roślinnych oraz zbadanie potencjału kolorystycznego wybranych ziół. Jako testowane rośliny wybrano lawsonię bezbronną, ketmię szczawiową, rzewień, bez czarny oraz rumianek pospolity. Aby ukazać wpływ procesu koloryzacji na strukturę oraz wygląd: kory, otoczki i rdzenia włosów, użyto wideodermatoskopu. Naturalną metodę farbowania włosów cechuje niższy potencjał alergizujący w stosunku do syntetycznej. Jednak biorąc pod uwagę ograniczenia kolorysty…

Quantum dot/cyclodextrin supramolecular systems based on efficient molecular recognition and their use for sensing.

2011

A supramolecular system based on ketoprofen functionalised CdSe/ZnS nanoparticles and pyrene-modified β-CD was prepared and successfully used for molecular sensing of different analytes. In addition, a strategy for the individual recovery of all the components of the sensing assay is reported.