Related Experiment Video
Updated: Nov 11, 2025
08:04
Controlling Flow Speeds of Microtubule-Based 3D Active Fluids Using Temperature
Published on: November 26, 2019
7.4K
Active carpets drive non-equilibrium diffusion and enhanced molecular fluxes
Francisca Guzmán-Lastra1,2, Hartmut Löwen3, Arnold J T M Mathijssen4
1Escuela de Data Science, Facultad de Estudios Interdisciplinarios, Universidad Mayor, Santiago, Chile. franciscaglastra@gmail.com.
Nature Communications
|March 27, 2021
Summary
Active carpets create non-equilibrium conditions, enhancing molecular transport. This study derives generalized Fick's laws to explain enhanced diffusion and particle repulsion from active surfaces.
Area of Science:
- Physics
- Physical Chemistry
- Biophysics
Background:
- Biological activity is concentrated on surfaces, creating 'active carpets' that inject energy into fluids.
- Existing diffusion laws (Fick's laws) apply near equilibrium, but non-equilibrium transport from active surfaces is not well understood.
Purpose of the Study:
- To derive enhanced diffusivity near active carpets.
- To develop generalized Fick's laws for non-equilibrium transport.
- To investigate particle behavior and molecular flux driven by active surfaces.
Main Methods:
- Derived enhanced diffusivity as a function of distance from an active carpet.
- Adapted Schnitzer's telegraph model to create generalized Fick's laws.
- Solved archetypal problems involving sedimentation and diffusion to/from active surfaces.
Main Results:
- Quantified enhanced diffusivity near active carpets.
- Demonstrated a 'self-cleaning' effect where active surfaces can repel sedimenting particles.
- Showed significantly increased molecular flux to active sinks compared to thermal diffusion.
Conclusions:
- Developed a framework for understanding non-equilibrium transport driven by active surfaces.
- Results elucidate properties of active materials and life at interfaces.
- Findings have implications for self-cleaning surfaces and nutrient capture by organisms.
Related Concept Videos
01:12Diffusion
212.2K
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...
212.2K
01:21Diffusion
5.8K
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...
5.8K
01:17Passive Diffusion: Overview and Kinetics
1.0K
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...
When administered orally, drugs establish a substantial concentration gradient between the gastrointestinal (GI) lumen and the bloodstream, expediting...
1.0K
01:21Carrier Transport
699
The generation of electrical current in semiconductors is fundamentally driven by two mechanisms: drift and diffusion. These processes are essential for the functionality and performance of semiconductor-based devices.
Drift Current:
The drift of charge carriers is started by an external electric field (E). Charged particles, such as electrons and holes, experience an acceleration between collisions with lattice atoms. For electrons, this results in a drift velocity (vd) given by:
Drift Current:
The drift of charge carriers is started by an external electric field (E). Charged particles, such as electrons and holes, experience an acceleration between collisions with lattice atoms. For electrons, this results in a drift velocity (vd) given by:
699
01:24Protein Diffusion in the Membrane
5.1K
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...
5.1K
03:48Behavior of Gas Molecules: Molecular Diffusion, Mean Free Path, and Effusion
30.3K
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...
30.3K