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Related Concept Videos

Diffusion01:12

Diffusion

Diffusion is the passive movement of substances down their concentration gradients—requiring no expenditure of cellular energy. Substances, such as molecules or ions, diffuse from an area of high concentration to an area of low concentration in the cytosol or across membranes. Eventually, the concentration will even out, with the substance moving randomly but causing no net change in concentration. Such a state is called dynamic equilibrium, which is essential for maintaining overall...
Diffusion01:21

Diffusion

Diffusion is a type of passive transport. In passive transport, a substance tends to move from an area of high concentration to an area of low concentration until the concentration is equal across the space. For example, take the diffusion of substances through the air. When someone opens a perfume bottle in a room filled with people, the perfume is at its highest concentration in the bottle and is at its lowest at the edges of the room. The perfume vapor will diffuse, or spread away, from the...
Protein Diffusion in the Membrane01:24

Protein Diffusion in the Membrane

Proteins show rotational as well as lateral diffusion across the membrane. The lateral diffusion of proteins was confirmed through the cell fusion experiment where mouse and human cells were fused, resulting in hybrid cells. When the human and mouse cells fused, the specific membrane proteins on human and mouse cells were marked with the red and green-fluorescent markers, respectively. Initially, the red and green fluorescence was located on the respective hemisphere of the cell. As time...
Passive Diffusion: Overview and Kinetics01:17

Passive Diffusion: Overview and Kinetics

Passive diffusion is a critical process that allows small lipophilic drugs to cross the cell membrane along a concentration gradient. This mechanism's efficiency depends on four primary factors: the membrane's surface area, the drug's lipid-water partition coefficient, the concentration gradient, and the membrane's thickness.
When administered orally, drugs establish a substantial concentration gradient between the gastrointestinal (GI) lumen and the bloodstream, expediting their diffusion into...
Behavior of Gas Molecules: Molecular Diffusion, Mean Free Path, and Effusion03:48

Behavior of Gas Molecules: Molecular Diffusion, Mean Free Path, and Effusion

Although gaseous molecules travel at tremendous speeds (hundreds of meters per second), they collide with other gaseous molecules and travel in many different directions before reaching the desired target. At room temperature, a gaseous molecule will experience billions of collisions per second. The mean free path is the average distance a molecule travels between collisions. The mean free path increases with decreasing pressure; in general, the mean free path for a gaseous molecule will be...
Boundary Layer Characteristics01:18

Boundary Layer Characteristics

When a fluid encounters a solid surface, a boundary layer forms due to the interaction between the fluid's motion and the stationary surface. This phenomenon is characterized by a thin region adjacent to the surface where viscous forces dominate, influencing the fluid's velocity profile. The development of the boundary layer begins at the leading edge of the surface and evolves as the fluid moves downstream.As the fluid flows over the surface, friction between the fluid and the wall slows down...

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Related Experiment Video

Updated: May 18, 2026

Spot Variation Fluorescence Correlation Spectroscopy for Analysis of Molecular Diffusion at the Plasma Membrane of Living Cells
05:56

Spot Variation Fluorescence Correlation Spectroscopy for Analysis of Molecular Diffusion at the Plasma Membrane of Living Cells

Published on: November 12, 2020

Faster diffusion across an irregular boundary.

A Rozanova-Pierrat1, D S Grebenkov, B Sapoval

  • 1Laboratoire de Physique de la Matière Condensée, C.N.R.S.-Ecole Polytechnique, 91128 Palaiseau, France. anna.rozanova-pierrat@ecp.fr

Physical Review Letters
|September 26, 2012
PubMed
Summary
This summary is machine-generated.

Irregularly shaped radiators enhance heat transfer for pulsed heat sources at short times. While initially efficient, their cooling performance diminishes over time, with fractal geometry offering better heat dissipation than simple irregular shapes.

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Last Updated: May 18, 2026

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The Diffusion of Passive Tracers in Laminar Shear Flow
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Published on: May 1, 2018

Area of Science:

  • Thermodynamics
  • Materials Science
  • Heat Transfer

Background:

  • Understanding heat transfer is crucial for designing efficient cooling systems.
  • The influence of radiator shape on heat dissipation dynamics is an active research area.
  • Existing models may not fully capture heat propagation near complex surfaces.

Purpose of the Study:

  • To investigate the impact of heat source shape on heat transfer efficiency.
  • To visualize heat propagation from prefractal radiators.
  • To evaluate the effectiveness of irregularly shaped passive coolers.

Main Methods:

  • Experimental setup for direct visualization of heat propagation.
  • Numerical simulations to model heat transfer dynamics.
  • Analysis of temperature distribution near irregular radiator surfaces.

Main Results:

  • Irregularly shaped passive coolers exhibit rapid heat dissipation at short times.
  • Cooling efficiency of irregular radiators decreases over time.
  • The de Gennes scaling argument is an approximation insufficient for short-range temperature distribution near irregular frontiers.

Conclusions:

  • Radiators with irregular surfaces enhance cooling of pulsed heat sources, particularly at short durations.
  • Fractal geometry plays a role in heat dissipation dynamics.
  • Further research is needed to refine models for heat transfer near complex surfaces.