scholarly journals Selective excitation enables encoding and measurement of multiple diffusion parameters in a single experiment

2021 ◽  
Vol 2 (2) ◽  
pp. 835-842
Author(s):  
Neil MacKinnon ◽  
Mehrdad Alinaghian ◽  
Pedro Silva ◽  
Thomas Gloge ◽  
Burkhard Luy ◽  
...  
Keyword(s):  
Diffusion Coefficient ◽  
Eddy Current ◽  
Anisotropic Diffusion ◽  
Selective Excitation ◽  
Diffusion Measurement ◽  
Single Experiment ◽  
Diffusion Constants ◽  
Diffusion Parameters ◽  
Gradient Amplitude ◽  
Proof Of Principle

Abstract. Band selectivity to address specific resonances in a spectrum enables one to encode individual settings for diffusion experiments. In a single experiment, this could include different gradient strengths (enabling coverage of a larger range of diffusion constants), different diffusion delays, or different gradient directions (enabling anisotropic diffusion measurement). In this report, a selective variant of the bipolar pulsed gradient eddy current delay (BPP-LED) experiment, enabling selective encoding of three resonances, was implemented. As proof of principle, the diffusion encoding gradient amplitude was assigned a range dependent on the selected signal, thereby allowing the extraction of the diffusion coefficient for water and a tripeptide (Met-Ala-Ser) with optimal settings in a single experiment.

scholarly journals Selective excitation enables encoding and measurement of multiple diffusion parameters in a single experiment

2021 ◽  
Author(s):  
Neil MacKinnon ◽  
Mehrdad Alinaghian ◽  
Pedro Silva ◽  
Thomas Gloge ◽  
Burkhard Luy ◽  
...  
Keyword(s):  
Diffusion Coefficient ◽  
Eddy Current ◽  
Anisotropic Diffusion ◽  
Selective Excitation ◽  
Diffusion Measurement ◽  
Single Experiment ◽  
Diffusion Constants ◽  
Diffusion Parameters ◽  
Gradient Amplitude ◽  
Proof Of Principle

Abstract. Band selectivity to address specific resonances in a spectrum enables one to encode individual settings for diffusion experiments. In a single experiment, this could include different gradient strengths (enabling coverage of a larger range of diffusion constants), different diffusion delays, or different gradient directions (enabling anisotropic diffusion measurement). In this report a selective variant of the bipolar pulsed gradient, eddy-current delay (BPP-LED) experiment enabling selective encoding of three resonances was implemented. As proof-of-principle, the diffusion encoding gradient amplitude was assigned a range dependent on the selected signal, thereby allowing the extraction of the diffusion coefficient for water and a tripeptide (Met-Ala-Ser) with optimal settings in a single experiment.

Anisotropy in the Dicke Narrowing of Rotational Raman Lines (A New Measure of the Nonsphericity of Intermolecular Forces)

1972 ◽  
Vol 50 (8) ◽  
pp. 778-782 ◽  
Author(s):  
B. K. Gupta ◽  
S. Hess ◽  
A. D. May
Keyword(s):  
Diffusion Coefficient ◽  
Physical Interpretation ◽  
Anisotropic Diffusion ◽  
Scattered Light ◽  
Intermolecular Forces ◽  
Gaseous Hydrogen ◽  
Experimental Results ◽  
Scattering Angle ◽  
Collision Model

The diffusion coefficient characterizing the Dicke narrowing of the rotational Raman lines, in general, depends on the polarizations of the incident and scattered light and on the scattering angle. Experimental results for the anisotropic diffusion coefficient are presented for 90° scattering and vv and vh polarizations of the S0(1) line in gaseous hydrogen. The physical interpretation of the observed anisotropy is given with the help of a simple collision model.

Anisotropic diffusion of oxygen in slices of rat muscle

1984 ◽  
Vol 246 (1) ◽  
pp. R107-R113 ◽  
Author(s):  
L. D. Homer ◽  
J. B. Shelton ◽  
C. H. Dorsey ◽  
T. J. Williams
Keyword(s):  
Diffusion Coefficient ◽  
Fluorescence Quenching ◽  
Muscle Fiber ◽  
Extracellular Space ◽  
Anisotropic Diffusion ◽  
Muscle Fibers ◽  
Rat Muscle ◽  
Hamstring Muscles ◽  
Standard Deviations ◽  
Diffusion Coefficient Of Oxygen

The diffusion coefficient of oxygen (D) and the fluorescence quenching coefficient (K') of pyrenebutyric acid (PBA) were measured in sections of rat hamstring muscles. Values of D and K' at temperatures (Tc) of 20, 30, and 40 degrees C were determined and referred to the values in water. In sections cut parallel to the muscle fibers, D = DH2O (0.380 +/- 0.038), whereas in sections cut across the grain of the fibers, D = DH2O (0.985 +/- 0.039). Oxygen diffuses along the length of a muscle fiber over twice as rapidly as it diffuses in directions perpendicular to the long axis of the fiber. This suggests that fibers, myofibrils, or myofilaments offer substantial barriers to the diffusion of oxygen, whereas extracellular space and spaces around fibers or myofibrils or myofilaments offer no more resistance than water to the diffusion of oxygen. Corresponding estimates for K' were K' = K'H2O[0.14 (1 + 0.25 Tc)] and K' = K'H2O[0.21 (1 + 0.25 Tc)] for slices cut parallel to the long axis of muscle fibers and across the long axis, respectively. Standard deviations of K' were 9%.

scholarly journals A METHOD FOR THE DETERMINATION OF DIFFUSION CONSTANTS AND THE CALCULATION OF THE RADIUS AND WEIGHT OF THE HEMOGLOBIN MOLECULE

1929 ◽  
Vol 12 (4) ◽  
pp. 543-554 ◽  
Author(s):  
John H. Northrop ◽  
M. L. Anson
Keyword(s):  
Molecular Weight ◽  
Carbon Monoxide ◽  
Diffusion Coefficient ◽  
Porous Membrane ◽  
Diffusion Constants ◽  
Einstein's Equation ◽  
Hemoglobin Molecule

A method is described for determining the diffusion coefficient of solutes by determining the rate of passage of the solute through a thin porous membrane between two solutions of different concentration. The method has been used to determine the diffusion coefficient of carbon monoxide hemoglobin. This was found to be 0.0420 ± 0.0005 cm.2 per day at 5°C. The molecular weight of carbon monoxide hemoglobin calculated by means of Einstein's equation from this quantity is 68,600 ± 1,000.

scholarly journals Interactions of Human Fibrinogen in Solution

1977 ◽  
Author(s):  
E. Serrallach ◽  
W. Känzig ◽  
V. Hofmann ◽  
P.W. Straub ◽  
M. Zulauf
Keyword(s):  
Diffusion Coefficient ◽  
Brownian Motion ◽  
Rotational Diffusion ◽  
Sedimentation Coefficient ◽  
Translational Diffusion ◽  
Initial Slope ◽  
Single Pair ◽  
Human Fibrinogen ◽  
Diffusion Constants ◽  
End To End

The intriguing diversity of published translational diffusion constants for the fibrinogen molecule can hardly be explained, unless interactions between the molecules are postulated. In the present study we have investigated the possible effect of molecular association and electrostatic intermolecular interactions on the Brownian motion. The translational diffusion coefficient DT, the rotational diffusion coefficient around the minor axis DR and the sedimentation coefficient have been measured. The methods used were dynamic light scattering and analytical ultracentrifugation. The samples were solutions of purified human fibrinogen. The correlation-function corresponding to DT deviates from a single exponential. The initial slope is found to depend on concentration, being DT = (1.7 ± 0.3) 10-7 cm2/s at 10mg/ml, pH 7.4 and 0.15 molar Tris-NaCl, and increases at fibrinogen concentrations below 2mg/ml. These results are compatible with a polydispers solution, in which single molecules are in equilibrium with pair and higher aggregates. The nature of the aggregates is end-to-end as indicated from the difference between the two rotational diffusion constants DR = 40000 ± 20% and DR = 10000 ±30% s-1. On the basis of the Hall-Slayter model and assumption of end-to-end association we calculated the ratio of the sedimentation coefficient of single, pair and triplet associates, being 1:1.14:1.20. Therefore, it is difficult to separate them in a sedimentation run. For ionic strength below 0.05 molar and low fibrinogen concentration (0.lmg/ml) a fast decay appears in the correlation, indicating that the Brownian motion is strongly influenced by electrostatic interactions.

scholarly journals Anisotropic diffusion of fluorescently labeled ATP in rat cardiomyocytes determined by raster image correlation spectroscopy

2008 ◽  
Vol 295 (5) ◽  
pp. C1302-C1315 ◽  
Author(s):  
Marko Vendelin ◽  
Rikke Birkedal
Keyword(s):  
Diffusion Coefficient ◽  
Diffusion Coefficients ◽  
Anisotropic Diffusion ◽  
Correlation Spectroscopy ◽  
Image Correlation ◽  
Rat Cardiomyocytes ◽  
Intracellular Diffusion ◽  
Average Diffusion ◽  
Image Correlation Spectroscopy ◽  
Kinetics Of

A series of experimental data points to the existence of profound diffusion restrictions of ADP/ATP in rat cardiomyocytes. This assumption is required to explain the measurements of kinetics of respiration, sarcoplasmic reticulum loading with calcium, and kinetics of ATP-sensitive potassium channels. To be able to analyze and estimate the role of intracellular diffusion restrictions on bioenergetics, the intracellular diffusion coefficients of metabolites have to be determined. The aim of this work was to develop a practical method for determining diffusion coefficients in anisotropic medium and to estimate the overall diffusion coefficients of fluorescently labeled ATP in rat cardiomyocytes. For that, we have extended raster image correlation spectroscopy (RICS) protocols to be able to discriminate the anisotropy in the diffusion coefficient tensor. Using this extended protocol, we estimated diffusion coefficients of ATP labeled with the fluorescent conjugate Alexa Fluor 647 (Alexa-ATP). In the analysis, we assumed that the diffusion tensor can be described by two values: diffusion coefficient along the myofibril and that across it. The average diffusion coefficients found for Alexa-ATP were as follows: 83 ± 14 μm2/s in the longitudinal and 52 ± 16 μm2/s in the transverse directions ( n = 8, mean ± SD). Those values are ∼2 (longitudinal) and ∼3.5 (transverse) times smaller than the diffusion coefficient value estimated for the surrounding solution. Such uneven reduction of average diffusion coefficient leads to anisotropic diffusion in rat cardiomyocytes. Although the source for such anisotropy is uncertain, we speculate that it may be induced by the ordered pattern of intracellular structures in rat cardiomyocytes.

A Simple Diffusion Cell for the Determination of Absolute Diffusion Constants using Radioactive Tracers

1971 ◽  
Vol 49 (9) ◽  
pp. 1575-1578 ◽  
Author(s):  
Willy Dyck
Keyword(s):  
Diffusion Coefficient ◽  
Bulk Diffusion ◽  
Ion Concentration ◽  
Detectable Effect ◽  
Diffusion Cell ◽  
Simple Diffusion ◽  
Hydrogen Ion Concentration ◽  
Self Diffusion ◽  
Diffusion Constants

Using microscope slides for the diffusion grating, a glass diffusion cell was constructed which permitted the determination of absolute diffusion constants of γ-ray emitting elements in aqueous solutions.The cell was tested at 25 °C with 110Ag as tracer and gave a bulk-diffusion coefficient of 1.64 × 10 −5 cm2/s and a self-diffusion coefficient of 1.48 × 10−5 cm2/s using 0.01 M AgNO3.The hydrogen ion concentration had no detectable effect on the diffusion coefficient of AgNO3 in the pH range −0.48 to 7.5. The presence of Na or Fe(III) ions, or sucrose molecules at moderate concentrations (> 0.1 M) resulted in a marked decrease in the diffusion coefficient.

Li ion Conduction in Cross-Linked Peo-LiCF3SO3 Complex

1988 ◽  
Vol 135 ◽  
Author(s):  
Jun Tsuchiya
Keyword(s):  
Diffusion Coefficient ◽  
Room Temperature ◽  
Transport Number ◽  
Diffusion Measurement ◽  
Poly Ethylene Oxide ◽  
Li Ion ◽  
Poly Ethylene ◽  
Pfg Nmr ◽  
And Diffusion ◽  
Ion Transport Number

AbstractIonic migration of cross-linked amorphous Poly (Ethylene Oxide)-LiCF3SO3was investigated by measuring ionic conductivity and diffusion coefficient. Pulsed-Field-Gradient NMR (PFG-NMR) was used for the diffusion measurement. The measurements were carried out at a temperature region between room temperature and 120°C. The PFG-NMR mea-surement shows the two modes of migration of both cation(Li) and anion (CF3 SO3-) for specimens containing plasticizer (CH30(CHeiH20)gH3C). The two modes of migration for anion are present for specimens without the plasticizer. Li+ transport number is found to be less than 0.1 for specimens without the plasticizer. Plasticizer is found to increase the Li+ ion transport number.

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