Search results for "Fluorescence"

ChemInform Abstract: Blue Fluorescent Exciplexes Consisting of trans-Stilbene and Antibodies.

2010

Chemoselektive Fluoreszenzstudien am Subtilisin und “Thiosubtilisin”

1985

Chemoselective Fluorescence Studies with Subtilisin and “Thiosubtilisin” The serine hydroxy group in the active site of subtilisin is selectively “phosphylated”3). This is demonstrated using the fluorescent phosphinic fluoride 1. “Thiosubtilisin” does not react with 1 but with the SH-selective and fluorescent vinyl sulfone 2.

Comparison of epifluorescence microscopy and flow cytometry in counting freshwater picophytoplankton

2021

The smaller the phytoplankton, the greater effort is required to distinguish individual cells by optics-based methods. Flow cytometry is widely applied in marine picophytoplankton research, but in freshwater research its role has remained minor. We compared epifluorescence microscopy and flow cytometry in assessing the composition, abundance and cell sizes of autofluorescent picophytoplankton in epilimnia of 46 Finnish lakes. Phycocyaninrich picocyanobacteria were the most dominant. The two methods yielded comparable total picophytoplankton abundances, but the determination of cell sizes, and thus total biomasses, were on average an order of magnitude higher in the microscopy results. Howev…

Diabetes mellitus: evaluation of erythrocyte and polymorphonuclear leukocyte rheology

2015

Aim: To explore red blood cells (RBC) and leukocyte rheology, that may be relevant in the pathophysiology of diabetes mellitus. Methods and Results: Significant alterations have been observed in RBC behaviour using several filtration techniques, but the exploration of RBC deformability by laser diffractometry did not show any abnormality. We have also employed microrheological methods based on fluorescence spectroscopy: membrane microviscosity was evaluated in ghosts, while in intact RBC we explored the membrane polarity gradient using fluorescent fatty acids, the phospholipid and protein lateral mobility using respectively pyrene and pyrene-3-maleimide. Alterations emerged only using the l…

A sun-induced vegetation fluorescence retrieval method from top of atmosphere radiance for the FLEX/Sentinel-3 TanDEM mission

2015

A new fluorescence retrieval method is proposed to support ESA's 8th Earth Explorer FLuorescence EXplorer/Sentinel-3 (FLEX-S3) candidate tandem mission. FLEX is the first mission specially dedicated to measure the Sun-Induced vegetation chlorophyll fluorescence (SIF) strongly related with the vegetation photosynthetic activity. Most hyperspectral fluorescence retrieval algorithms available in the literature are very sensitive to true reflectance modelization and/or they assume the atmospheric status as known. The proposed algorithm delivers the retrieval of full fluorescence spectrum at canopy level by using only Top Of Atmosphere (TOA) radiances from S3 and FLEX as input. Once the spatial …

Unsupervised clustering method for pattern recognition in IIF images

2017

Autoimmune diseases are a family of more than 80 chronic, and often disabling, illnesses that develop when underlying defects in the immune system lead the body to attack its own organs, tissues, and cells. Diagnosis of autoimmune pathologies is based on research and identification of antinuclear antibodies (ANA) through indirect immunofluorescence (IIF) method and is performed by analyzing patterns and fluorescence intensity. We propose here a method to automatically classify the centromere pattern based on the grouping of centromeres on the cells through a clustering K-means algorithm. The described method was tested on a public database (MIVIA). The results of the test showed an Accuracy…

Cyclotriveratrylene-Containing Porphyrins

2016

International audience; The C-3-symmetric cyclotriveratrylene (CTV) was covalently bonded via click chemistry to 1, 2, 3, and 6 zinc(II) porphyrin units to various host for C-60. The binding constants, Ka, were measured from the quenching of the porphyrin fluorescence by C-60. These constants vary between 400 and 4000 M-1 and are considered weak. Computer modeling demonstrated that the zinc(II) porphyrin units, [Zn], exhibit a strong tendency to occupy the CTV cavity, hence blocking the access for C-60 to land on this site. Instead, the pincer of the type [Zn]-[Zn] and in one case [Zn]-CTV, were found to be the most probable geometry to promote host-guest associations in these systems.

The Structural Diversity of Benzofuran Resorcinarene Leads to Enhanced Fluorescence

2014

An unexpected and previously unknown resorcinarene mono-crown with a fused benzofuran moiety in its macrocyclic core was obtained as a byproduct from a bridging reaction of tetramethoxy resorcinarene with tetraethylene glycol ditosylate. The formation of the fused benzofuran moiety in the resorcinarene macrocycle resulted in a unique rigid and puckered boat conformation, as shown by XRD studies in the solid state. Modification of the macrocycle was also observed to affect the photophysical properties in solution by enhancing the fluorescence brightness compared with a conventional resorcinarene macrocycle. The fluorescent properties enabled unique detection of structural features, that is, …

Upscaling leaf gas exchange measurements to the whole grapevine canopy: An update

2009

This review first revisits current knowledge about single-leaf function, viz. photosynthesis, chiefly in relation to environmental factors, that underscores the importance of multiple summer stresses. Emphasis is placed on the response different genotypes show under light and heat stress with or without soil-water shortage. Secondly, it tackles the thorny issue of extrapolating single-leaf readings to the whole-canopy level, with special reference to both methodological and physiological implications. Whole-canopy gas-exchange systems deliver and emphasise the usefulness of such an approach in achieving key research goals. One case in point is quantifying the amount and dynamics of canopy g…

Nitrogen-Doped Carbon Nanodots-Ionogels: Preparation, Characterization, and Radical Scavenging Activity

2018

Hybrid diimidazolium-based ionogels were obtained by dispersing nitrogen-doped carbon nanodots (NCNDs) in ionic liquid (IL) solutions and by using dicationic organic salts as gelators. The properties of the NCND-ionogels were studied in terms of thermal stability, mechanical strength, morphology, rheological, and microscopic analyses. Insights into the formation of the hybrid soft material were attained from kinetics of sol-gel phase transition and from estimating the size of the aggregates, obtained from opacity and resonance light-scattering measurements. We demonstrate that, on one hand, NCNDs were able to favor the gel formation both in the presence of gelating and nongelating ILs. On t…