scholarly journals Background fluorescence reduction and absorption correction for fluorescence reflectance imaging

2014 ◽  
Author(s):  
F. Fantoni ◽  
L. Hervé ◽  
V. Poher ◽  
S. Gioux ◽  
J. I. Mars ◽  
...  
Keyword(s):  
Background Fluorescence ◽  
Fluorescence Reflectance Imaging ◽  
Absorption Correction

Gaussian ϕ(ρz) curves: Comparison with other models

1990 ◽  
Vol 48 (2) ◽  
pp. 192-193
Author(s):  
Alberto Riveros ◽  
Gustavo Castellano
Keyword(s):  
Good Description ◽  
Bulk Sample ◽  
Incident Electron Energy ◽  
Power Mean ◽  
General Shape ◽  
Ionization Cross ◽  
X Ray ◽  
Mass Absorption ◽  
Absorption Correction ◽  
Image Position

X ray characteristic intensity Ii , emerging from element i in a bulk sample irradiated with an electron beam may be obtained throughwhere the function ϕi(ρz) is the distribution of ionizations for element i with the mass depth ρz, ψ is the take-off angle and μi the mass absorption coefficient to the radiation of element i.A number of models has been proposed for ϕ(ρz), involving several features concerning the interaction of electrons with matter, e.g. ionization cross section, stopping power, mean ionization potential, electron backscattering, mass absorption coefficients (MAC’s). Several expressions have been developed for these parameters, on which the accuracy of the correction procedures depends.A great number of experimental data and Monte Carlo simulations show that the general shape of ϕ(ρz) curves remains substantially the same when changing the incident electron energy or the sample material. These variables appear in the parameters involved in the expressions for ϕ(ρz). A good description of this function will produce an adequate combined atomic number and absorption correction.

point-Analysis Using the Extrapolation Method in the Analytical Electron microscope

1990 ◽  
Vol 48 (2) ◽  
pp. 430-431
Author(s):  
Zenji Horita ◽  
Ryuzo Nishimachi ◽  
Takeshi Sano ◽  
Minoru Nemoto
Keyword(s):  
Electron Microscope ◽  
Extrapolation Method ◽  
X Ray ◽  
Absorption Correction ◽  
Point Analysis ◽  
Analytical Electron ◽  
Analytical Electron Microscope ◽  
Data Points ◽  
Identical Composition ◽  
X Ray Absorption

Absorption correction is often required in quantitative x-ray microanalysis of thin specimens using the analytical electron microscope. For such correction, it is convenient to use the extrapolation method[l] because the thickness, density and mass absorption coefficient are not necessary in the method. The characteristic x-ray intensities measured for the analysis are only requirement for the absorption correction. However, to achieve extrapolation, it is imperative to obtain data points more than two at different thicknesses in the identical composition. Thus, the method encounters difficulty in analyzing a region equivalent to beam size or the specimen with uniform thickness. The purpose of this study is to modify the method so that extrapolation becomes feasible in such limited conditions. Applicability of the new form is examined by using a standard sample and then it is applied to quantification of phases in a Ni-Al-W ternary alloy.The earlier equation for the extrapolation method was formulated based on the facts that the magnitude of x-ray absorption increases with increasing thickness and that the intensity of a characteristic x-ray exhibiting negligible absorption in the specimen is used as a measure of thickness.

scholarly journals Fluorescence background discrimination by prebleaching.

1979 ◽  
Vol 27 (1) ◽  
pp. 96-101 ◽  
Author(s):  
T Hirschfeld
Keyword(s):  
Fluorescent Dyes ◽  
Fluorescence Decay ◽  
Free Form ◽  
Alternative Procedure ◽  
Background Fluorescence ◽  
Decay Lifetime ◽  
Fluorescent Molecules ◽  
Background Contrast

A number of electrooptical techniques are described that discriminate against background fluorescence in biologic staining, whether from sample background or unbound excess stain. These techniques are based on the fluorescent decay lifetime difference between bound stain and the sample background or between the bound stain its free form. The fluorescence decay lifetimes may be measured either directly or in a combination gated photometry scheme to substantially enhance the sample background contrast. An alternative procedure uses the photochemical bleaching of fluorescent dyes under intense exposure to time discriminate with higher selectivity, sensitivity and in a more convenient fashion between diverse fluorescent molecules.

Development of software and modification of Q-FISH protocol for estimation of individual telomere length in immunopathology

2017 ◽  
Vol 15 (02) ◽  
pp. 1650041 ◽  
Author(s):  
M. Sh. Barkovskaya ◽  
A. G. Bogomolov ◽  
N. Yu. Knauer ◽  
N. B. Rubtsov ◽  
V. A. Kozlov
Keyword(s):  
Telomere Length ◽  
Inflammatory Diseases ◽  
Quantitative Information ◽  
Computer Assisted ◽  
Metaphase Chromosomes ◽  
Important Indicator ◽  
Background Fluorescence ◽  
Immune Mediated ◽  
Light Effects ◽  
Assisted Analysis

Telomere length is an important indicator of proliferative cell history and potential. Decreasing telomere length in the cells of an immune system can indicate immune aging in immune-mediated and chronic inflammatory diseases. Quantitative fluorescent in situ hybridization (Q-FISH) of a labeled (C3TA[Formula: see text] peptide nucleic acid probe onto fixed metaphase cells followed by digital image microscopy allows the evaluation of telomere length in the arms of individual chromosomes. Computer-assisted analysis of microscopic images can provide quantitative information on the number of telomeric repeats in individual telomeres. We developed new software to estimate telomere length. The MeTeLen software contains new options that can be used to solve some Q-FISH and microscopy problems, including correction of irregular light effects and elimination of background fluorescence. The identification and description of chromosomes and chromosome regions are essential to the Q-FISH technique. To improve the quality of cytogenetic analysis after Q-FISH, we optimized the temperature and time of DNA-denaturation to get better DAPI-banding of metaphase chromosomes. MeTeLen was tested by comparing telomere length estimations for sister chromatids, background fluorescence estimations, and correction of nonuniform light effects. The application of the developed software for analysis of telomere length in patients with rheumatoid arthritis was demonstrated.

scholarly journals A sandwich-like strategy for the label-free detection of oligonucleotides by surface plasmon fluorescence spectroscopy (SPFS)

The Analyst ◽  
2016 ◽  
Vol 141 (20) ◽  
pp. 5784-5791 ◽  
Author(s):  
Qiang Su ◽  
Gilbert Nöll
Keyword(s):  
Fluorescence Spectroscopy ◽  
Surface Plasmon ◽  
Molecular Beacons ◽  
Label Free ◽  
Background Fluorescence ◽  
Detection Strategy ◽  
Cutting Surface ◽  
Label Free Detection ◽  
Lower Background

Cutting surface-bound optical molecular beacons results in a sandwich-like detection strategy with lower background fluorescence.

Refinement of the crystal structure of metatorbernite

1993 ◽  
Vol 205 (1) ◽  
pp. 1-7 ◽  
Author(s):  
A. C. Stergiou ◽  
P. J. Rentzeperis ◽  
S. Sklavounos
Keyword(s):  
Crystal Structure ◽  
Least Squares ◽  
Anomalous Dispersion ◽  
Thermal Parameters ◽  
Water Molecules ◽  
Full Matrix ◽  
Absorption Correction ◽  
Atom Position ◽  
Oxygen Atoms

AbstractThe crystal structure of metatorbernite with composition CuThe positional and thermal parameters were refined by full-matrix least-squares calculations. Absorption correction and correction for anomalous dispersion, for all atoms, were applied. The finalThe structure is essentially similar to that described by M. Ross, H. Evans and D. Appleman (1964) for metatorbernite, with a difference in the Cu atom position, which here is 1/4 1/4 0.31 instead of 1/4 1/4 0.80. The U atoms are six-coordinated by two O atoms (uranyl group) and four phosphate – oxygen atoms forming an asymmetrical tetragonal dipyramid. The Cu atoms are six-coordinated by two oxygen atoms of two different uranyl groups and four water molecules forming also an asymmetrical tetragonal dipyramid. The four water molecules form squares Cu(H

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