Related Experiment Video
Updated: Jun 23, 2026
08:04
Controlling Flow Speeds of Microtubule-Based 3D Active Fluids Using Temperature
Published on: November 26, 2019
Aging and effective temperatures near a critical point
S Joubaud1, B Percier, A Petrosyan
1Université de Lyon, Laboratoire de Physique, Ecole Normale Supérieure de Lyon, CNRS, 46, Allée d'Italie, 69364 Lyon Cedex 07, France.
Physical Review Letters
|April 28, 2009
Summary
Liquid crystals exhibit aging properties after an electric field quench near the Fréedericksz transition due to critical slowing down. An effective temperature, higher than the bath temperature, is observed during this slow relaxation process.
Area of Science:
- Physics
- Materials Science
- Soft Matter Physics
Background:
- Liquid crystals exhibit complex dynamic behavior near phase transitions.
- The Fréedericksz transition is a critical electric-field-driven transition in liquid crystals.
- Understanding dynamic properties in non-equilibrium systems is crucial.
Purpose of the Study:
- To investigate the dynamic behavior of liquid crystals after a quench near the Fréedericksz transition.
- To identify aging phenomena in liquid crystals under critical slowing down conditions.
- To measure the effective temperature during slow relaxation using fluctuation-dissipation relations.
Main Methods:
- Experimental measurement of director orientation fluctuations in liquid crystals.
- Quenching the system near the Fréedericksz transition point.
- Analysis of correlation and response functions for power law scaling.
- Application of the fluctuation-dissipation relation to determine effective temperature.
Main Results:
- Experimental evidence of aging properties in liquid crystals after a quench.
- Observation of critical slowing down leading to power law scaling in relaxation dynamics.
- Demonstration of a well-defined effective temperature significantly exceeding the heat bath temperature.
- Validation of the fluctuation-dissipation relation in an aging soft matter system.
Conclusions:
- Liquid crystals near the Fréedericksz transition exhibit aging behavior characteristic of non-equilibrium systems.
- Critical slowing down plays a key role in the observed slow relaxation dynamics.
- The concept of effective temperature is applicable and measurable in these aging liquid crystal systems.
Related Concept Videos
01:18pV-Diagrams
The pV diagram, which is a graph of pressure versus volume of the gas under study, is helpful in describing certain aspects of the substance. When the substance behaves like an ideal gas, the ideal gas equation describes the relationship between its pressure and volume. On a pV diagram, it is common to plot an isotherm, which is a curve showing p as a function of V with the number of molecules and the temperature fixed. Then, for an ideal gas, the product of the pressure of the gas and its...
02:39Phase Transitions: Melting and Freezing
Heating a crystalline solid increases the average energy of its atoms, molecules, or ions, and the solid gets hotter. At some point, the added energy becomes large enough to partially overcome the forces holding the molecules or ions of the solid in their fixed positions, and the solid begins the process of transitioning to the liquid state or melting. At this point, the temperature of the solid stops rising, despite the continual input of heat, and it remains constant until all of the solid is...
02:44Heating and Cooling Curves
When a substance—isolated from its environment—is subjected to heat changes, corresponding changes in temperature and phase of the substance is observed; this is graphically represented by heating and cooling curves.
For instance, the addition of heat raises the temperature of a solid; the amount of heat absorbed depends on the heat capacity of the solid (q = mcsolidΔT). According to thermochemistry, the relation between the amount of heat absorbed or released by a substance, q, and its...
For instance, the addition of heat raises the temperature of a solid; the amount of heat absorbed depends on the heat capacity of the solid (q = mcsolidΔT). According to thermochemistry, the relation between the amount of heat absorbed or released by a substance, q, and its...
01:23Physical Methods for Controlling Microbial Growth: Temperature
Heat is a widely used method to control microbial growth by targeting and denaturing cellular proteins, thereby killing or inactivating microbes. This method's effectiveness is quantified using parameters such as the thermal death point (TDP), thermal death time (TDT), and decimal reduction time (D value). TDP represents the lowest temperature at which all microorganisms in a liquid suspension are eliminated within 10 minutes, whereas TDT is the time necessary to achieve sterilization at a...
01:27Factors Influencing Microbial Growth: Temperature
Microorganisms display remarkable adaptations, enabling them to thrive in diverse ecological niches across a wide range of temperatures. Temperature profoundly influences microbial growth by affecting enzymatic activity, membrane fluidity, and other cellular processes.Each microorganism operates within a specific temperature range defined by three cardinal points: minimum, optimum, and maximum. Below the minimum temperature, membranes lose fluidity, halting transport processes. Above the...
01:11Temperature and Thermal Equilibrium
Heat and temperature are essential concepts for everyone every day. The study of heat and temperature is part of an area of physics known as thermodynamics. It is not always easy to distinguish heat and temperature.
The concept of temperature has evolved from the common concepts of hot and cold. The scientific definition of temperature explains more than just our sense of hot and cold. Temperature is operationally defined as the quantity measured with a thermometer. Furthermore, temperature is...
The concept of temperature has evolved from the common concepts of hot and cold. The scientific definition of temperature explains more than just our sense of hot and cold. Temperature is operationally defined as the quantity measured with a thermometer. Furthermore, temperature is...