Interplay between translational diffusion and large-amplitude angular jumps of water molecules

2018 ◽  
Vol 148 (18) ◽  
pp. 184502 ◽  
Author(s):  
Chao Liu ◽  
Yangyang Zhang ◽  
Jian Zhang ◽  
Jun Wang ◽  
Wenfei Li ◽  
...  
Keyword(s):  
Large Amplitude ◽  
Translational Diffusion ◽  
Water Molecules

Evidence of Surface Diffusion of Water Molecules on Proteins of Rabbit Lens by NMR Relaxation Measurements

1996 ◽  
Vol 51 (1-2) ◽  
pp. 81-90 ◽  
Author(s):  
Jerzy Bodurka ◽  
Gerd Buntkowsky ◽  
Aleksander Gutsze
Keyword(s):  
Surface Diffusion ◽  
Spin Relaxation ◽  
Rotational Diffusion ◽  
Activation Energies ◽  
Translational Diffusion ◽  
Spin Lattice Relaxation ◽  
Dynamic Processes ◽  
Water Molecules ◽  
Relaxation Measurements ◽  
Translational Surface

Abstract In this work, we propose a relaxation model for the interpretation of NMR proton spinlattice and spin-spin relaxation times of mammalian lenses. The framework for this model is based on nuclear magnetic spin-lattice relaxation measurements as a function of tem perature at different Larmor frequencies for whole rabbit lenses and fragments of the lens. According to this model, two different dynamic processes of the water molecules determine the relaxation behaviour, namely rotational diffusion and translational surface diffusion. These dynamic processes in conjuction with a two site exchange model give a good explanation of all the measured relaxation data. From the experimental data, we were able to obtain the activation parameters for rotational and translational diffusion of bound lens water. Correlation times of 2.1×10-11 sec and 2.5×10-9 sec and activation energies of 20.5 kJ/mol and 22.5 kJ/mol respectively were found at 308K. At low Larmor frequencies (≤ MHz) the longitudinal relaxation is mainly determined by translational surface diffusion of bound water with a mean square displacement of 1.5 nm, whereas at higher frequencies (≥300 MHz), rotational diffusion is the main relaxation mechanism. The spin-spin relaxation is determined by translational diffusion over the whole frequency range and therefore shows only a very small dispersion. By our model it is possible to explain: 1) the strikingly large difference between the T1 value and the T2A and T2B values observed in the lens and 2 ) the different values of the activation energies measured at different fields for the lens.

Neutron Scattering Study on Dynamics of Water Molecules in MCM-41. 2. Determination of Translational Diffusion Coefficient

2005 ◽  
Vol 109 (22) ◽  
pp. 11231-11239 ◽  
Author(s):  
Shuichi Takahara ◽  
Naoya Sumiyama ◽  
Shigeharu Kittaka ◽  
Toshio Yamaguchi ◽  
Marie-Claire Bellissent-Funel
Keyword(s):  
Diffusion Coefficient ◽  
Neutron Scattering ◽  
Translational Diffusion ◽  
Water Molecules ◽  
Translational Diffusion Coefficient ◽  
Scattering Study ◽  
Neutron Scattering Study ◽  
Mcm 41

On nearly-commensurable periods in the restricted problem of three bodies, with calculations of the long-period variations in the interior 2:1 case

1966 ◽  
Vol 25 ◽  
pp. 197-222 ◽  
Author(s):  
P. J. Message
Keyword(s):  
Periodic Solution ◽  
Periodic Solutions ◽  
Large Amplitude ◽  
Restricted Problem ◽  
Small Amplitude ◽  
Minor Planets ◽  
Long Period ◽  
Numerical Integrations ◽  
Period Variations ◽  
The Mean

An analytical discussion of that case of motion in the restricted problem, in which the mean motions of the infinitesimal, and smaller-massed, bodies about the larger one are nearly in the ratio of two small integers displays the existence of a series of periodic solutions which, for commensurabilities of the typep+ 1:p, includes solutions of Poincaré'sdeuxième sortewhen the commensurability is very close, and of thepremière sortewhen it is less close. A linear treatment of the long-period variations of the elements, valid for motions in which the elements remain close to a particular periodic solution of this type, shows the continuity of near-commensurable motion with other motion, and some of the properties of long-period librations of small amplitude.To extend the investigation to other types of motion near commensurability, numerical integrations of the equations for the long-period variations of the elements were carried out for the 2:1 interior case (of which the planet 108 “Hecuba” is an example) to survey those motions in which the eccentricity takes values less than 0·1. An investigation of the effect of the large amplitude perturbations near commensurability on a distribution of minor planets, which is originally uniform over mean motion, shows a “draining off” effect from the vicinity of exact commensurability of a magnitude large enough to account for the observed gap in the distribution at the 2:1 commensurability.

Heterogeneity of Size and Distribution of Intramembrane Particles in the Plasma Membrane of Yeast

1977 ◽  
Vol 35 ◽  
pp. 596-597
Author(s):  
E. Keyhani
Keyword(s):  
Plasma Membrane ◽  
Candida Utilis ◽  
Synthetic Medium ◽  
Freeze Fracture ◽  
Translational Diffusion ◽  
Yeast Cells ◽  
Distilled Water ◽  
Intramembrane Particles ◽  
The Matrix ◽  
Water Cell

The matrix of biological membranes consists of a lipid bilayer into which proteins or protein aggregates are intercalated. Freeze-fracture techni- ques permit these proteins, perhaps in association with lipids, to be visualized in the hydrophobic regions of the membrane. Thus, numerous intramembrane particles (IMP) have been found on the fracture faces of membranes from a wide variety of cells (1-3). A recognized property of IMP is their tendency to form aggregates in response to changes in experi- mental conditions (4,5), perhaps as a result of translational diffusion through the viscous plane of the membrane. The purpose of this communica- tion is to describe the distribution and size of IMP in the plasma membrane of yeast (Candida utilis).Yeast cells (ATCC 8205) were grown in synthetic medium (6), and then harvested after 16 hours of culture, and washed twice in distilled water. Cell pellets were suspended in growth medium supplemented with 30% glycerol and incubated for 30 minutes at 0°C, centrifuged, and prepared for freeze-fracture, as described earlier (2,3).

Information and estimation in image processing

1987 ◽  
Vol 45 ◽  
pp. 14-17
Author(s):  
B. Roy Frieden
Keyword(s):  
Image Processing ◽  
Optical System ◽  
Large Amplitude ◽  
Communication Theory ◽  
Image Data ◽  
Direct Approach ◽  
Ill Posed

Despite the skill and determination of electro-optical system designers, the images acquired using their best designs often suffer from blur and noise. The aim of an “image enhancer” such as myself is to improve these poor images, usually by digital means, such that they better resemble the true, “optical object,” input to the system. This problem is notoriously “ill-posed,” i.e. any direct approach at inversion of the image data suffers strongly from the presence of even a small amount of noise in the data. In fact, the fluctuations engendered in neighboring output values tend to be strongly negative-correlated, so that the output spatially oscillates up and down, with large amplitude, about the true object. What can be done about this situation? As we shall see, various concepts taken from statistical communication theory have proven to be of real use in attacking this problem. We offer below a brief summary of these concepts.

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