Search results for "Phasor"

Phasor FLIM analysis of Thioflavin T fluorescence in protein amyloid aggregates: Mapping molecular interactions.

Thioflavin T (ThT) is a worldwide used dye to monitor protein aggregation as it stains with a certain specificity amyloid structures. The interactions between ThT and its hosts are largely studied suggesting that fluorescence properties of this dye critically depend both on the environment rigidity, electrostatic and hydrophobic properties as well as on molecular details binding site structure. Here FLIM and phasor approach analysis are used to exploit ThT amyloid interactions and, in turn, to address polymorphism and structural heterogeneity of amyloid species mapping aggregate-to-aggregate structural differences and revealing details of molecular architecture within the same aggregate.

Spectral identification of forced oscillation in PMU signal using mode decomposition

2018

This article gives a new method to identify the frequency of Forced Oscillation (FO) in phasor measurement units (PMUs) signals. The processing of the signal by Empirical Mode Decomposition (EMD) technique leads to effective detection with improvement in accuracy. After testing some improved versions of EMD, it is observed that ‘improved Complete Ensemble Empirical Mode Decomposition with Adaptive Noise (CEEMDAN-2014)’ is the best version to use in processing. The developed methodology is able to spot the frequency of FOs even if there exist multiple modes with mode mixing and multiple events. In such cases, self-coherence method fails to spot FO. Spectral analysis is conducted on the decom…

Studio e sviluppo di innovativi sistemi di misura e di comunicazione per le smart grid

Phasor-FLIM analysis of Thioflavin T self-quenching in Concanavalin amyloid fibrils

2020

The formation of amyloid structures has traditionally been related to human neurodegenerative pathologies and, in recent years, the interest in these highly stable nanostructures was extended to biomaterial sciences. A common method to monitor amyloid growth is the analysis of Thioflavin T fluorescence. The use of this highly selective dye, diffused worldwide, allows mechanistic studies of supramolecular assemblies also giving back important insight on the structure of these aggregates. Here we present experimental evidence of self-quenching effect of Thioflavin T in presence of amyloid fibrils. A significant reduction of fluorescence lifetime of this dye which is not related to the propert…

Multispectral fluorescence sensitivity to acidic and polyphenolic changes in Chardonnay wines – The case study of malolactic fermentation

2022

International audience; In this study, stationary and time-resolvedfluorescence signatures, were statistically and chemometrically analyzed among three typologies of Chardonnay wines (A, B and C) with the objectives to evaluate their sensitivity to acidic and polyphenolic changes. For that purpose, a dataset was built using Excitation Emission Matrices of fluorescence (N = 103) decomposed by a Parallel Factor Analysis (PARAFAC), andfluorescence decays (N = 22), mathematically fitted, using the conventional exponential modeling and the phasor plot representation. Wine PARAFAC component C4 coupledwith its phasor plot g and s values enable the description of malolactic fermentation (MLF) occur…

Direct observation of alpha-lactalbumin, adsorption and incorporation into lipid membrane and formation of lipid/protein hybrid structures

2019

The interaction between proteins and membranes is of great interest in biomedical and biotechnological research for its implication in many functional and dysfunctional processes. We present an experimental study on the interaction between model membranes and alpha-lactalbumin (alpha-La). alpha-La is widely studied for both its biological function and its anti-tumoral properties. We use advanced fluorescence microscopy and spectroscopy techniques to characterize alpha-La-membrane mechanisms of interaction and alpha-La-induced modifications of membranes when insertion of partially disordered regions of protein chains in the lipid bilayer is favored. Moreover, using fluorescence lifetime imag…

A method for the investigation of high-order two-frequency asynchronous oscillators

1992

A general method for analysing asynchronous high-order two-frequency oscillators is presented. the oscillator model is made up of a GC non-linear parallel group embedded in a linear lumped time-invariant network of any order. the approach devised rests on the identification of a pair of narrow-band impedance operators which permit one to derive first-approximation steady state and dynamic equations in the phasor domain—as well as stability criteria—in a simple and expressive manner. Previous results from averaging and perturbation treatments on fourth-order asynchronous oscillators are shown to be obtainable from this theory as particular cases. the sixth-order oscillator chosen as an appli…

Phase error analysis of clipped waveforms in surface topography measurement using projected fringes

2021

Abstract When working with the method of projected fringes outside the optical laboratory one often encounters the problem of uncontrollable ambient light. This might cause saturation of the camera which in turn results in clipping of the fringes. Since standard theories describing phase-shifting techniques assume the projected fringes to be purely sinusoidal, such clipping will result in measurement error. In this paper a detailed analysis of this problem is given, and relations between phase errors, the amount of fringe clipping and the number of phase steps are found. Moreover, the phase difference between the clipped and the unclipped fringes is described. This investigation is based on…

Development of multidimensional spectroscopic and microscopic techniques to facilitate the monitoring of native fluorescence of biomolecules.

2022

There is a need for the development of rapid and reliable characterization tools for biological media. The objective of this thesis is to develop a method based on the acquisition of excitation-emission matrices of fluorescence (EEMF) coupled with the use of fluorescence lifetime measurement in spectroscopy and microscopy (FLIM). These techniques have great potential due to their speed, low sample volume required for analysis, non-destructive sample analysis, and low cost. This project focused on two biological media of great interest to the food industry: wine and bacterial spores. On one hand, we have a beverage representing a large world market, and on the other hand, a food contaminant …

Phasor total unbalance power: Formulation and some properties

2007

Unbalance power has been used to quantify unbalance phenomenon effects in the electric power systems for a long time. Expressions of this power developed by some different theories only give the value of its module. Therefore, total unbalance power values in electric power systems cannot be obtained by the unbalance power values of each of their loads. For that, it is necessary to express the unbalance power as a complex number. In this paper the unbalance power is expressed in phasor notation and some of their properties are described, applied to electric systems with balanced voltages. Results are verified by simulation and also practical comparative experiences are realized in actual ins…