Related Experiment Video
Updated: May 18, 2026
08:37
Forming, Confining, and Observing Microtubule-Based Active Nematics
Published on: January 13, 2023
Surface and bulk contributions to nematic order reconstruction
A Amoddeo1, R Barberi, G Lombardo
1Mechanics and Materials Department, Università "Mediterranea" di Reggio Calabria, I-89122 Reggio Calabria, Italy. antonino.amoddeo@unirc.it
Physical Review. E, Statistical, Nonlinear, and Soft Matter Physics
|September 26, 2012
Summary
We studied nematic molecules in asymmetric cells under electric fields, observing how order variations change with electric pulse strength and surface anchoring. Our method distinguishes bulk and surface order reconstruction.
Area of Science:
- Materials Science
- Soft Matter Physics
- Liquid Crystal Physics
Background:
- Nematic molecules in asymmetric cells show textural distortions under electric fields.
- Landau-de Gennes Q-tensor theory describes nematic order variations.
- Understanding these variations is crucial for device applications.
Purpose of the Study:
- Investigate nematic order variations in asymmetric cells subjected to electric fields.
- Analyze the impact of electric pulse amplitude and surface pretilt anchoring angles.
- Develop a method to distinguish bulk and surface order reconstruction.
Main Methods:
- Implemented a Q-tensor model.
- Utilized a moving mesh finite element method.
- Simulated nematic molecules confined in an asymmetric π cell.
Main Results:
- Observed textural distortions and nematic order variations.
- Quantified the evolution of order variations with electric field strength.
- Determined the influence of surface pretilt anchoring angles on order.
- Successfully differentiated between bulk and surface order reconstruction.
Conclusions:
- The study provides insights into the behavior of nematic molecules under external stimuli.
- The developed technique effectively distinguishes bulk and surface phenomena.
- Findings are relevant for designing and optimizing liquid crystal devices.
Related Concept Videos
02:06Newman Projections
Different notations are used to represent the three-dimensional structure of molecules on two-dimensional surfaces. One of the most commonly used representations is the dash-wedge formula. The dashed wedges, solid wedges, and the plane lines indicate the groups situated behind the plane, coming out of the plane, and in the plane, respectively.
The organic molecules rotate across the single bonds leading to numerous temporary three-dimensional structures of varying energy known as conformers.
The organic molecules rotate across the single bonds leading to numerous temporary three-dimensional structures of varying energy known as conformers.
01:16Surface Tension and Surface Energy
When a paint brush is immersed in water, the bristles wave freely inside the water. When it is taken out, the bristles stick together. The reason behind this effect is surface tension.
Consider a beaker filled with liquid. The bulk molecules in the liquid experience equal attractive forces on all sides with the surrounding molecules. However, the surface molecules experience a net attractive force downward due to the bulk molecules. The surface of the liquid behaves like a stretched membrane,...
Consider a beaker filled with liquid. The bulk molecules in the liquid experience equal attractive forces on all sides with the surrounding molecules. However, the surface molecules experience a net attractive force downward due to the bulk molecules. The surface of the liquid behaves like a stretched membrane,...
01:10Interpreting ¹H NMR Signal Splitting: The (n + 1) Rule
In the AX proton spin system, proton A can sense the two spin states of a coupled proton X, resulting in a doublet NMR signal with two peaks of equal (1:1) intensity. When proton A is coupled to two equivalent protons (AX2 spin system), the spin states of each X can be aligned with or against the external field, creating three possible scenarios. This results in a 1:2:1 triplet signal, where the central peak corresponds to the chemical shift of A and is twice as large or intense as the others.
01:14NMR Spectrometers: Resolution and Error Correction
When magnetic nuclei in a sample achieve resonance and undergo relaxation, the signal detected in NMR is an approximately exponential free induction decay. Fourier transform of an exponential decay yields a Lorentzian peak in the frequency domain. Lorentzian peaks in an NMR spectrum are defined by their amplitude, full width at half maximum, and position, where the peak width is governed by the spin-spin relaxation time alone. In real experiments, however, the applied magnetic field is rendered...