Fluorescence lifetime characterization of bacteria using total lifetime distribution analysis with the maximum entropy method

1997 ◽  
Vol 7 (3) ◽  
pp. 201-210 ◽  
Author(s):  
Amy E. Kinkennon ◽  
Linda B. McGown
Keyword(s):  
Maximum Entropy ◽  
Fluorescence Lifetime ◽  
Maximum Entropy Method ◽  
Entropy Method ◽  
Lifetime Distribution ◽  
Distribution Analysis ◽  
Total Lifetime

Improved maximum entropy method for the analysis of fluorescence spectroscopy data: evaluating zero-time shift and assessing its effect on the determination of fluorescence lifetimes

The Analyst ◽  
2015 ◽  
Vol 140 (24) ◽  
pp. 8138-8147 ◽  
Author(s):  
Rosario Esposito ◽  
Giuseppe Mensitieri ◽  
Sergio de Nicola
Keyword(s):  
Maximum Entropy ◽  
Maximum Entropy Method ◽  
Entropy Method ◽  
Lifetime Distribution ◽  
Time Shift ◽  
Fluorescence Lifetimes ◽  
Time Resolved Fluorescence ◽  
Time Resolved ◽  
Zero Time

A new algorithm based on the Maximum Entropy Method (MEM) is proposed for recovering the lifetime distribution and the zero-time shift from experimental time-resolved fluorescence decays.

scholarly journals Topological properties of hydrogen bonds and covalent bonds from charge densities obtained by the maximum entropy method (MEM)

2009 ◽  
Vol 65 (5) ◽  
pp. 624-638 ◽  
Author(s):  
Jeanette Netzel ◽  
Sander van Smaalen
Keyword(s):  
Hydrogen Bonds ◽  
Maximum Entropy ◽  
Maximum Entropy Method ◽  
Dynamic Deformation ◽  
Entropy Method ◽  
Topological Properties ◽  
Covalent Bonds ◽  
Charge Densities

Charge densities have been determined by the Maximum Entropy Method (MEM) from the high-resolution, low-temperature (T ≃ 20 K) X-ray diffraction data of six different crystals of amino acids and peptides. A comparison of dynamic deformation densities of the MEM with static and dynamic deformation densities of multipole models shows that the MEM may lead to a better description of the electron density in hydrogen bonds in cases where the multipole model has been restricted to isotropic displacement parameters and low-order multipoles (l max = 1) for the H atoms. Topological properties at bond critical points (BCPs) are found to depend systematically on the bond length, but with different functions for covalent C—C, C—N and C—O bonds, and for hydrogen bonds together with covalent C—H and N—H bonds. Similar dependencies are known for AIM properties derived from static multipole densities. The ratio of potential and kinetic energy densities |V(BCP)|/G(BCP) is successfully used for a classification of hydrogen bonds according to their distance d(H...O) between the H atom and the acceptor atom. The classification based on MEM densities coincides with the usual classification of hydrogen bonds as strong, intermediate and weak [Jeffrey (1997). An Introduction to Hydrogen Bonding. Oxford University Press]. MEM and procrystal densities lead to similar values of the densities at the BCPs of hydrogen bonds, but differences are shown to prevail, such that it is found that only the true charge density, represented by MEM densities, the multipole model or some other method can lead to the correct characterization of chemical bonding. Our results do not confirm suggestions in the literature that the promolecule density might be sufficient for a characterization of hydrogen bonds.

scholarly journals Characterization of Local Distortions in Thermoelectric Lead Chalcogenides

2014 ◽  
Vol 70 (a1) ◽  
pp. C106-C106
Author(s):  
Niels Bindzus ◽  
Sebastian Christensen ◽  
Mogens Christensen ◽  
Bo Iversen
Keyword(s):  
Neutron Diffraction ◽  
Maximum Entropy ◽  
Diffraction Data ◽  
Thermoelectric Materials ◽  
Maximum Entropy Method ◽  
Entropy Method ◽  
Neutron Diffraction Data ◽  
Lead Chalcogenides ◽  
X Ray

Thermoelectric materials are functional materials with the unique ability to interconvert heat and electricity, holding much promise for green energy solutions such as efficient waste heat recovery. The extraordinary thermoelectric performance of binary lead chalcogenides has caused huge research activity, but the mechanisms governing their unexpected low thermal conductivity still remain a controversial topic. It has been proposed to result from giant anharmonic phonon scattering or from local fluctuating dipoles on the Pb site, emerging with temperature on the Pb site.[1,2] No macroscopic symmetry change are associated with these effects, rendering them invisible to conventional crystallographic techniques. For this reason lead chalcogenides were until recently believed to adopt the ideal, undistorted rock-salt structure. In the present study, we probe the peculiar structural features in PbX (X = S, Se, Te) using multi-temperature synchrotron powder X-ray diffraction data in combination with the maximum entropy method. Distorted atoms are detected and quantified by refinement of anharmonic probability density functions. The charge density analysis is complemented by nuclear density distributions (NDDs) reconstructed from neutron diffraction data and by a novel method: Nuclear Enhanced X-ray Maximum Entropy Method (NEXMEM). NEXMEM offers an alternative route to experimental NDDs, exploiting the superior quality of synchrotron X-ray data compared to neutron diffraction data. The increased atomic resolution introduced by NEXMEM proved essential for resolving atomic distortions, see figure below showing Pb in the (100) plane. Our findings outline the extent of disorder and anharmonicity in binary lead chalcogenides, promoting our fundamental understanding of this class of high-performance thermoelectric materials. The applied approach can be used in general, opening up for widespread characterization of subtle features in crystals with unusual properties.

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