diffusion

Examples of diffusion in the following topics:

• Diffusion

  • Diffusion is the movement of particles from regions of high concentration towards regions of lower concentration.
  • Molecular diffusion, often called simply diffusion, is the thermal motion of all (liquid or gas) particles at temperatures above absolute zero.
  • However, diffusion can still occur in the absence of a concentration gradient.
  • The result of diffusion is a gradual mixing of material.
  • Discuss the process and results of diffusion, identifying factors that affect its rate

• Molecular Transport Phenomena

  • These include diffusion and osmosis.
  • More massive molecules diffuse more slowly.
  • This type of diffusion is called free diffusion, because there are no barriers inhibiting it.
  • The rate of diffusion is also proportional to the diffusion constant D, which is determined experimentally.
  • Some of the most interesting examples of diffusion occur through barriers that affect the rates of diffusion.

• Nerve Conduction and Electrocardiograms

  • Free ions will diffuse from a region of high concentration to one of low concentration.
  • Diffusion of K+ and Cl− thus creates the layers of positive and negative charge on the outside and inside of the membrane, and the Coulomb force prevents the ions from diffusing across in their entirety .
  • The result is two layers of charge right on the membrane, with diffusion being balanced by the Coulomb force.
  • The membrane thus temporarily becomes permeable to Na+, which then rushes in, driven both by diffusion and the Coulomb force.
  • Diffusion moves the K+ and Cl− ions in the direction shown, until the Coulomb force halts further transfer.

• Introduction

  • We are going to set the stage for a deeper look at astrophysical sources of radiation by defining the important concepts of radiative transfer, thermal radiation and radiative diffusion.

• Biological and Medical Applications

  • Diffusion is the movement of substances due to random thermal molecular motion.
  • Fluids can even diffuse through solids (such as fumes or odors entering ice cubes).
  • Diffusion is the dominant mechanism by which the exchange of nutrients and waste products occurs between the blood and tissue, and between air and blood in the lungs.
  • In the evolutionary process, as organisms became larger they needed quicker methods of transportation than net diffusion, due to the larger distances involved in the transport.
  • Less sophisticated, single-celled organisms still rely totally on diffusion for the removal of waste products and the uptake of nutrients.

• The Law of Reflection and Its Consequences

  • However, light strikes different parts of a rough surface at different angles, and it is reflected in many different directions ("diffused").
  • Diffused light is what allows us to see a sheet of paper from any angle.

• Steady Supersonic Flow

  • If the area of the pipe increases (diffuser) in the direction of the flow, the velocity decreases and the pressure and density increase.
  • If the area of the pipe increases (diffuser) in the direction of the flow, the velocity increases and the pressure and density decrease.

• Electric Potential in Human

  • This can occur passively, as ions diffuse through ion channels in the membrane.

• Gamma Rays

  • Gamma rays and neutrons are more penetrating, causing diffuse damage throughout the body (e.g., radiation sickness, cell's DNA damage, cell death due to damaged DNA, increasing incidence of cancer) rather than burns.
  • External radiation exposure should also be distinguished from internal exposure, due to ingested or inhaled radioactive substances, which, depending on the substance's chemical nature, can produce both diffuse and localized internal damage.

• Geomagnetism

  • In this equation u is the velocity of the fluid, B is the magnetic field, and eta is the magnetic diffusivity.
  • The first term on the right hand side of the induction equation is a diffusion term.