A characteristic spectral emission is observed in vegetation chlorophyll under excitation by solar radiation. This emission, known as solar-induced chlorophyll fluorescence, occurs in the red and near infra-red spectral regions. In this paper a new methodology for the estimation of solar-induced chlorophyll fluorescence from spaceborne and airborne sensors is presented. The fluorescence signal ...

The UV-dissipative mechanisms of the eumelanin building block 5,6-dihydroxyindole-2-carboxylic acid (DHICA) and the 4,7-dideutero derivative (DHICA-d(2)) in buffered H(2)O or D(2)O have been characterized by using ultrafast time-resolved fluorescence spectroscopy. Excitation of the carboxylate anion form, the dominating state at neutral pH, leads to dual fluorescence. The band peaking at lambda...

Riboflavin (vitamin B2, RF) is taken up in eukaryotic cells via specialized transport mechanisms. Although RF has fluorescence properties, direct microscopic visualization of RF uptake and trafficking has been complicated by cellular autofluorescence. We describe the synthesis, cellular uptake characteristics, and spectroscopic properties of a novel rhodamine-riboflavin conjugate (RD-RF), inclu...

Aqueous dispersions of graphene oxide (GO) have been found to emit a structured, strongly pH-dependent visible fluorescence. Based on experimental results and model computations, this is proposed to arise from quasi-molecular fluorophores, similar to polycyclic aromatic compounds, formed by the electronic coupling of carboxylic acid groups with nearby carbon atoms of graphene. Sharp and structu...

We have implemented continuous-wave two-photon excitation of near-UV absorbing fluorophores in a scanning near-field optical microscope (SNOM). The 647-nm emission of an Ar-Kr mixed gas laser was used to excite the UV-absorbing DNA dyes DAPI, the bisbenzimidazole Hoechst 33342, and ethidium bromide in a shared aperture SNOM with uncoated fiber tips. Polytene chromosomes of Drosophila melanogast...

I. Bleached cells of Rhodopseudomonas spheroides, obtained by aerobic growth in the light, rapidly synthesize bacteriochlororphyll and earotenoids when transferred to 4 % oxygen in the dark. Fluorescence excitation spectra of whole cells during the initial stages of pigment synthesis indicate that the major fraction of the newly synthesized bacterioehlorophyll is immediately incorporated into p...

The advancement of far-red emitting variants of the green fluorescent protein (GFP) is crucially important for imaging live cells, tissues and organisms. Despite notable efforts, far-red marker proteins still need further optimization to match the performance of their green counterparts. Here we present mGarnet, a robust monomeric marker protein with far-red fluorescence peaking at 670 nm. Than...

Using Weber's method of "matrix analysis" for the estimation of the number of fluorescent species contributing to the emission of a sample, it is shown that the fluorescence(1) band in spinach chloroplast fragments at room temperature originates in two species of chlorophyll a. Emission spectra obtained upon excitation with different wavelengths of light (preferentially absorbed in chlorophyll ...

objective(s):cefixime (cfx), is a semi-synthetic third-generation oral cephalosporin antibiotic that is prescribed for the treatment of susceptible infections. there are some procedures for the determination of cfx in pharmaceutical formulations and biological samples. herein a spectrofluorimetric method was proposed for cfx determination based on the fluorescence quenching of terbium-danofloxa...

A rapid and sensitive HPLC method has been developed for the quantification of mirtazapine (MRZ), a noradrenergic and specific serotonergic inhibitor antidepressant (NaSSA) and its two major metabolites N-desmethylmirtazapine (NDM) and 8-hydroxymirtazapine (8-OHM) in human plasma. The separation was achieved using Chromolith C18 column and a mobile phase of acetonitrile: phosphate buffer (pH=3,...