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I dont want to discourage the improvement of the technical information in the article. I think this is of great value to those who can understand it, but I would guess this to be less than 5% of the readers. I would like to see a greatly simplified qualitative description of the process, so the reader who has heard the term, but has no background in physics and is mathematically challenged, can develop an idea of what diffusion means. For example, In diving theory diffusion is an important process in decompression and decompression sickness, but most divers only need to have a qualitative gut feel for why the gas particle move one way and not the other, and why the rate changes. This level of understanding would probably be useful to a larger number of users than the mathematical analysis. Peter (Southwood) (talk): 19:20, 1 June 2012 (UTC)
The definition of diffusion as the movement of a substance from a region of high concentration to a region of low concentration was the result of hundreds of years of research by scientists in many disciplines.
The removal of this definition is an utter disgrace. Moreover, the author of this page, Agor153, (I refer to them as the author as they appear to have made this page their personal mission) actually provides the very essence of the classic definition:
Consider: In Latin, "diffundere" means "to spread out". Logically, if something is "spreading out", it is moving from a region of high concentration to one of a lower concentration, i.e., it is DIFFUSING! Consider also that this very definition is illustrated in each of the three images/animations provided on the page.
How on earth is a young student supposed to grasp the most fundamental aspects of diffusion when the actual definition of the process is omitted?
Wikipedia is, unfortunately, the first port of call for many students who are trying to understand science - what chance do they have when they are met with a physics-driven personal project?
This also has knock-on effects. For example, "Facilitated Diffusion" was chosen as a term by scientists decades ago to accurately convey the mechanism for one of the most important cell transport mechanisms. The physiochemical properties of ions or molecules govern whether they can diffuse across cell membranes - from high to low concentration. Lipophobic/hydrophilic substances cannot cross the membrane due to the hydrophobic core of the phospholipid bilayer. Specialized transporter proteins (ion channels, transporter proteins) in the cell membrane "facilitate" (to make easier) the process of diffusion across the cell membrane, hence the name. However, this concept has now been lost within the facilitated diffusion wiki page as that page has also become the personal project for another user.
At this stage, I consider Wikipedia to be one of the biggest threats to STEM education due to the editing of its pages by subjective editors that show little regard for the multi-disciplinary nature of scientific discovery that led to the very definitions underpinning the titles of wiki pages.
[I'm an Associate Professor in the Departments of Physiology & Pharmacology and Large Animal Medicine at The University of Georgia; 20 years experience as a medical researcher and educator] — Preceding unsigned comment added by 96.32.136.122 ( talk) 23:15, 27 March 2014 (UTC)
I noticed that there is another Wikipedia article that talks about molecular diffusion. How is diffusion different from molecular diffusion? From reading that article: /info/en/?search=Molecular_diffusion , it seems like molecular diffusion and diffusion are synonyms. But, is it actually the case? Andrea.ns1005 ( talk) 02:16, 8 March 2020 (UTC)
Any information explaining what 'diffusion' means when the term is used for flows in diffuser/stator to explain the rise in static pressure would be really helpful, as googling the term brings up the application of the term without explaining it. Thank you. — Preceding unsigned comment added by 49.206.9.1 ( talk) 08:30, 23 May 2020 (UTC)
— Preceding unsigned comment added by 2601:2c3:4201:d70:6dfc:c22a:45fc:e601 ( talk) 07:00, 11 July 2021 (UTC)
— Preceding unsigned comment added by 2601:2c3:4201:d70:6dfc:c22a:45fc:e601 ( talk) 07:00, 11 July 2021 (UTC)
— Preceding unsigned comment added by 2601:2c3:4201:d70:6dfc:c22a:45fc:e601 ( talk) 07:00, 11 July 2021 (UTC)
This article was the subject of a Wiki Education Foundation-supported course assignment, between 25 February 2020 and 8 May 2020. Further details are available on the course page. Student editor(s): Kristinetole.
Above undated message substituted from Template:Dashboard.wikiedu.org assignment by PrimeBOT ( talk) 19:29, 16 January 2022 (UTC)
I just read through this article to see if I had something to contribute, and was slightly sad/shocked to find both serious and less serious, but significant, errors that need fixing. They are more than I have time to fix myself at the moment, so I was thinking I would bring some attention to them here.
Diffusion in the context of different disciplines : In chemistry and materials science, diffusion refers to the movement of fluid molecules in porous solids. In both chemistry and materials science, most diffusion processes of interest do not concern porous media. Diffusion in porous media is a small subset of the situations in which diffusion is relevant to these fields. (misleading)
Onsager's equations for multicomponent diffusion and thermodiffusion:
1) It should be stressed that the separate diffusion equations describe the mixing or mass transport without bulk motion. This is wrong, the diffusion equations in the relevant context describe the mass transport relative to some bulk velocity, meaning that the fluxes do not contribute to the bulk velocity.
2) Therefore, the terms with variation of the total pressure are neglected. It is possible for diffusion of small admixtures and for small gradients. The Onsager relations, and the non-equilibrium formalism has been shown to hold inside the front of shockwaves and across surfaces. Which are systems decidedly far outside equilibrium, and with large gradients. (misleading)
Nondiagonal diffusion must be nonlinear
A single article is cited as the source for this section. The authors of said article have forgotten that the gradients in a system are constrained by the Gibbs-Duhem equation. If one applies the Gibbs-Duhem equation to their argument, it falls apart. An important part of non-equilibrium thermodynamics concerns exactly the point of selecting appropriate independent force-flux pairs. What the cited article shows is that if one treats a dependent set of forces as an independent one, unphysical results will follow.
I'll start cleaning this up once I have time, unless someone strongly disagrees, in which case we can discuss it here first :) ItsBigBoat ( talk) 15:36, 15 December 2023 (UTC)
I think the section "Basic models of diffusion" would be much clearer if the subsections were named by the model discussed and that model started the section. Johnjbarton ( talk) 18:14, 17 December 2023 (UTC)
This
level-4 vital article is rated C-class on Wikipedia's
content assessment scale. It is of interest to the following WikiProjects: | |||||||||||||||||||||
|
This page has archives. Sections older than 365 days may be automatically archived by Lowercase sigmabot III when more than 10 sections are present. |
I dont want to discourage the improvement of the technical information in the article. I think this is of great value to those who can understand it, but I would guess this to be less than 5% of the readers. I would like to see a greatly simplified qualitative description of the process, so the reader who has heard the term, but has no background in physics and is mathematically challenged, can develop an idea of what diffusion means. For example, In diving theory diffusion is an important process in decompression and decompression sickness, but most divers only need to have a qualitative gut feel for why the gas particle move one way and not the other, and why the rate changes. This level of understanding would probably be useful to a larger number of users than the mathematical analysis. Peter (Southwood) (talk): 19:20, 1 June 2012 (UTC)
The definition of diffusion as the movement of a substance from a region of high concentration to a region of low concentration was the result of hundreds of years of research by scientists in many disciplines.
The removal of this definition is an utter disgrace. Moreover, the author of this page, Agor153, (I refer to them as the author as they appear to have made this page their personal mission) actually provides the very essence of the classic definition:
Consider: In Latin, "diffundere" means "to spread out". Logically, if something is "spreading out", it is moving from a region of high concentration to one of a lower concentration, i.e., it is DIFFUSING! Consider also that this very definition is illustrated in each of the three images/animations provided on the page.
How on earth is a young student supposed to grasp the most fundamental aspects of diffusion when the actual definition of the process is omitted?
Wikipedia is, unfortunately, the first port of call for many students who are trying to understand science - what chance do they have when they are met with a physics-driven personal project?
This also has knock-on effects. For example, "Facilitated Diffusion" was chosen as a term by scientists decades ago to accurately convey the mechanism for one of the most important cell transport mechanisms. The physiochemical properties of ions or molecules govern whether they can diffuse across cell membranes - from high to low concentration. Lipophobic/hydrophilic substances cannot cross the membrane due to the hydrophobic core of the phospholipid bilayer. Specialized transporter proteins (ion channels, transporter proteins) in the cell membrane "facilitate" (to make easier) the process of diffusion across the cell membrane, hence the name. However, this concept has now been lost within the facilitated diffusion wiki page as that page has also become the personal project for another user.
At this stage, I consider Wikipedia to be one of the biggest threats to STEM education due to the editing of its pages by subjective editors that show little regard for the multi-disciplinary nature of scientific discovery that led to the very definitions underpinning the titles of wiki pages.
[I'm an Associate Professor in the Departments of Physiology & Pharmacology and Large Animal Medicine at The University of Georgia; 20 years experience as a medical researcher and educator] — Preceding unsigned comment added by 96.32.136.122 ( talk) 23:15, 27 March 2014 (UTC)
I noticed that there is another Wikipedia article that talks about molecular diffusion. How is diffusion different from molecular diffusion? From reading that article: /info/en/?search=Molecular_diffusion , it seems like molecular diffusion and diffusion are synonyms. But, is it actually the case? Andrea.ns1005 ( talk) 02:16, 8 March 2020 (UTC)
Any information explaining what 'diffusion' means when the term is used for flows in diffuser/stator to explain the rise in static pressure would be really helpful, as googling the term brings up the application of the term without explaining it. Thank you. — Preceding unsigned comment added by 49.206.9.1 ( talk) 08:30, 23 May 2020 (UTC)
— Preceding unsigned comment added by 2601:2c3:4201:d70:6dfc:c22a:45fc:e601 ( talk) 07:00, 11 July 2021 (UTC)
— Preceding unsigned comment added by 2601:2c3:4201:d70:6dfc:c22a:45fc:e601 ( talk) 07:00, 11 July 2021 (UTC)
— Preceding unsigned comment added by 2601:2c3:4201:d70:6dfc:c22a:45fc:e601 ( talk) 07:00, 11 July 2021 (UTC)
This article was the subject of a Wiki Education Foundation-supported course assignment, between 25 February 2020 and 8 May 2020. Further details are available on the course page. Student editor(s): Kristinetole.
Above undated message substituted from Template:Dashboard.wikiedu.org assignment by PrimeBOT ( talk) 19:29, 16 January 2022 (UTC)
I just read through this article to see if I had something to contribute, and was slightly sad/shocked to find both serious and less serious, but significant, errors that need fixing. They are more than I have time to fix myself at the moment, so I was thinking I would bring some attention to them here.
Diffusion in the context of different disciplines : In chemistry and materials science, diffusion refers to the movement of fluid molecules in porous solids. In both chemistry and materials science, most diffusion processes of interest do not concern porous media. Diffusion in porous media is a small subset of the situations in which diffusion is relevant to these fields. (misleading)
Onsager's equations for multicomponent diffusion and thermodiffusion:
1) It should be stressed that the separate diffusion equations describe the mixing or mass transport without bulk motion. This is wrong, the diffusion equations in the relevant context describe the mass transport relative to some bulk velocity, meaning that the fluxes do not contribute to the bulk velocity.
2) Therefore, the terms with variation of the total pressure are neglected. It is possible for diffusion of small admixtures and for small gradients. The Onsager relations, and the non-equilibrium formalism has been shown to hold inside the front of shockwaves and across surfaces. Which are systems decidedly far outside equilibrium, and with large gradients. (misleading)
Nondiagonal diffusion must be nonlinear
A single article is cited as the source for this section. The authors of said article have forgotten that the gradients in a system are constrained by the Gibbs-Duhem equation. If one applies the Gibbs-Duhem equation to their argument, it falls apart. An important part of non-equilibrium thermodynamics concerns exactly the point of selecting appropriate independent force-flux pairs. What the cited article shows is that if one treats a dependent set of forces as an independent one, unphysical results will follow.
I'll start cleaning this up once I have time, unless someone strongly disagrees, in which case we can discuss it here first :) ItsBigBoat ( talk) 15:36, 15 December 2023 (UTC)
I think the section "Basic models of diffusion" would be much clearer if the subsections were named by the model discussed and that model started the section. Johnjbarton ( talk) 18:14, 17 December 2023 (UTC)