FLATTENING OF A SCRATCH ON ICE PURE SURFACE

In this work the evolution of the width of a line (groove) traced on the surface of a sample of bi-crystalline ice, by means of a metallic sheet, in a direction almost orthogonal to the grain edge (BG) was studied. To perform the measurements, the sample of ice submerged in ultrapure silicone oil was maintained at -5 ºC to prevent evaporation from occurring and isolate the effect of surface diffusion in this way. Photographs of the groove were periodically taken, approximately for 100 hours, using a camera coupled to an optical microscope. From these images the evolution of the line width was studied. Finally, the ice self-diffusion coefficient was determined at -5 ºC.

Download Full-text

Superficial self-diffusion coefficient in Ih-ICE

Czech Polar Reports ◽

10.5817/cpr2020-2-12 ◽

2020 ◽

Vol 10 (2) ◽

pp. 153-160

Author(s):

Carlos Leonardo Di Prinzio ◽

Damian Stoler ◽

Guillermo Aguirre Varela ◽

Esteban Druetta

Keyword(s):

Diffusion Coefficient ◽

Free Surface ◽

Grain Boundary ◽

Silicone Oil ◽

Optical Microscope ◽

Boundary Groove ◽

Self Diffusion ◽

Self Diffusion Coefficient

The evolution of the grain boundary groove in a bicrystalline ice sample was studied in this work. The groove is formed by the intersection of the grain boundary with the free surface. The bicrystalline ice sample had an arbitrary misorientation and was immersed in ultra-pure silicone oil at -5°C in order to avoid evaporation processes. Photographs of the groove were taken every 17 minutes for 100 hours with an optical microscope and the evolution of the groove was determined from these images. Through this study, it was possible to measure the coefficient of surface self-diffusion of the ice at -5°C.

Download Full-text

Effect of surface curvature on the determination of the self-diffusion coefficient

phys stat sol (a) ◽

10.1002/pssa.2210220250 ◽

1974 ◽

Vol 22 (2) ◽

pp. K139-K141 ◽

Cited By ~ 1

Author(s):

R. Lindström ◽

J. Aaltonen

Keyword(s):

Diffusion Coefficient ◽

Surface Curvature ◽

The Self ◽

Self Diffusion ◽

Self Diffusion Coefficient ◽

Effect Of Surface

Download Full-text

Effect of Modification on the Fluid Diffusion Coefficient in Silica Nanochannels

Molecules ◽

10.3390/molecules26134030 ◽

2021 ◽

Vol 26 (13) ◽

pp. 4030

Author(s):

Gengbiao Chen ◽

Zhiwen Liu

Keyword(s):

Diffusion Coefficient ◽

Diffusion Coefficients ◽

Surface Effect ◽

Bulk Water ◽

Self Diffusion ◽

Average Diffusion Coefficient ◽

Average Diffusion ◽

Chain Lengths ◽

Fluid Diffusion ◽

Self Diffusion Coefficient

The diffusion behavior of fluid water in nanochannels with hydroxylation of silica gel and silanization of different modified chain lengths was simulated by the equilibrium molecular dynamics method. The diffusion coefficient of fluid water was calculated by the Einstein method and the Green–Kubo method, so as to analyze the change rule between the modification degree of nanochannels and the diffusion coefficient of fluid water. The results showed that the diffusion coefficient of fluid water increased with the length of the modified chain. The average diffusion coefficient of fluid water in the hydroxylated nanochannels was 8.01% of the bulk water diffusion coefficient, and the diffusion coefficients of fluid water in the –(CH2)3CH3, –(CH2)7CH3, and –(CH2)11CH3 nanochannels were 44.10%, 49.72%, and 53.80% of the diffusion coefficients of bulk water, respectively. In the above four wall characteristic models, the diffusion coefficients in the z direction were smaller than those in the other directions. However, with an increase in the silylation degree, the increased self-diffusion coefficient due to the surface effect could basically offset the decreased self-diffusion coefficient owing to the scale effect. In the four nanochannels, when the local diffusion coefficient of fluid water was in the range of 8 Å close to the wall, Dz was greater than Dxy, and beyond the range of 8 Å of the wall, the Dz was smaller than Dxy.

Download Full-text

Insights into the interactions and dynamics of a DES formed by phenyl propionic acid and choline chloride

Scientific Reports ◽

10.1038/s41598-021-85260-z ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Parisa Jahanbakhsh Bonab ◽

Alireza Rastkar Ebrahimzadeh ◽

Jaber Jahanbin Sardroodi

Keyword(s):

Diffusion Coefficient ◽

Liquid Phase ◽

Propionic Acid ◽

Structural Parameters ◽

Choline Chloride ◽

Self Diffusion ◽

Phenyl Propionic Acid ◽

Donor And Acceptor ◽

Experimental Values ◽

Self Diffusion Coefficient

AbstractDeep eutectic solvents (DESs) have received much attention in modern green chemistry as inexpensive and easy to handle analogous ionic liquids. This work employed molecular dynamics techniques to investigate the structure and dynamics of a DES system composed of choline chloride and phenyl propionic acid as a hydrogen bond donor and acceptor, respectively. Dynamical parameters such as mean square displacement, liquid phase self-diffusion coefficient and viscosity are calculated at the pressure of 0.1 MPa and temperatures 293, 321 and 400 K. The system size effect on the self-diffusion coefficient of DES species was also examined. Structural parameters such as liquid phase densities, hydrogen bonds, molecular dipole moment of species, and radial and spatial distribution functions (RDF and SDF) were investigated. The viscosity of the studied system was compared with the experimental values recently reported in the literature. A good agreement was observed between simulated and experimental values. The electrostatic and van der Waals nonbonding interaction energies between species were also evaluated and interpreted in terms of temperature. These investigations could play a vital role in the future development of these designer solvents.

Download Full-text