scholarly journals Manifestation of Energy and Entropy of Particles in a Box

2022 ◽  
Author(s):  
Mohsen Farshad
Keyword(s):  
Binary Mixture ◽  
Degrees Of Freedom ◽  
Significant Contribution ◽  
Hard Spheres ◽  
Mixture Distribution ◽  
Two Component System ◽  
Large Particles ◽  
Two Component ◽  
Precise Prediction ◽  
Dynamics Simulations

The energy and entropy, expressed in free energy, determine the behavior of a system. Therefore, infinite knowledge of these two quantities leads to precise prediction of the system's trajectories. Here, we study how the energy and entropy affect the distribution of a two-component system in a box. First, using a model, we intuitively show that large particles prefer to position at contact with the wall as it accompanies an increase of the system's entropy. We intuitively show that this is a consequence of maximizing the accessible states for fluctuating degrees of freedom as a portion of excluded volumes reside outside of the box when they locate near the wall. Then we employ molecular dynamics simulations to extract the effect of entropy and energy on the binary mixture distribution and how they compete with each other to determine the system's configuration. While particle-particle and particle-wall attraction energies affect the distribution of particles, we show that the emergent entropic forces --- quasi-gravitational --- have a significant contribution to the configuration of the system. This system is realized clearly for a binary mixture of hard spheres in a box with reflective walls.

INELASTIC HARD SPHERES WITH RANDOM RESTITUTION COEFFICIENT: A NEW MODEL FOR HEATED GRANULAR FLUIDS

2001 ◽  
Vol 04 (04) ◽  
pp. 299-307 ◽  
Author(s):  
ALAIN BARRAT ◽  
EMMANUEL TRIZAC
Keyword(s):  
Velocity Distribution ◽  
Horizontal Plane ◽  
Degrees Of Freedom ◽  
Hard Spheres ◽  
Direct Simulation Monte Carlo ◽  
High Energy ◽  
Granular System ◽  
Restitution Coefficient ◽  
Particle Collisions ◽  
Dynamics Simulations

We consider a vertically shaken granular system interacting elastically with the vibrating boundary, so that the energy injected vertically is transferred to the horizontal degrees of freedom through inter-particle collisions only. This leads to collisions which, once projected onto the horizontal plane, become essentially stochastic and may have an effective restitution coefficient larger than unity. We therefore introduce the model of inelastic hard spheres with random restitution coefficient α (larger or smaller than unity) to describe granular systems heated by vibrations. In the non-equilibrium steady state, we focus in particular on the single particle velocity distribution f(v) in the horizontal plane, and on its deviation from a Maxwellian. We use Molecular Dynamics simulations and Direct Simulation Monte Carlo (DSMC) to show that, depending on the distribution of α, different shapes of f(v) can be obtained, with very different high energy tails. Moreover, the fourth cumulant of the velocity distribution (which quantifies the deviations from Gaussian statistics) is obtained analytically from the Boltzmann equation and successfully tested against the simulations.

scholarly journals Spatial segregation of mixed-sized counterions in dendritic polyelectrolytes

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
J. S. Kłos ◽  
J. Paturej
Keyword(s):  
Electrostatic Interactions ◽  
Spatial Separation ◽  
Excluded Volume ◽  
The Core ◽  
Bjerrum Length ◽  
Two Component ◽  
Conformational Properties ◽  
Dynamics Simulations ◽  
Two Parameters ◽  
Swelling Factor

AbstractLangevin dynamics simulations are utilized to study the structure of a dendritic polyelectrolyte embedded in two component mixtures comprised of conventional (small) and bulky counterions. We vary two parameters that trigger conformational properties of the dendrimer: the reduced Bjerrum length, $$\lambda _B^*$$ λ B ∗ , which controls the strength of electrostatic interactions and the number fraction of the bulky counterions, $$f_b$$ f b , which impacts on their steric repulsion. We find that the interplay between the electrostatic and the counterion excluded volume interactions affects the swelling behavior of the molecule. As compared to its neutral counterpart, for weak electrostatic couplings the charged dendrimer exists in swollen conformations whose size remains unaffected by $$f_b$$ f b . For intermediate couplings, the absorption of counterions into the pervaded volume of the dendrimer starts to influence its conformation. Here, the swelling factor exhibits a maximum which can be shifted by increasing $$f_b$$ f b . For strong electrostatic couplings the dendrimer deswells correspondingly to $$f_b$$ f b . In this regime a spatial separation of the counterions into core–shell microstructures is observed. The core of the dendrimer cage is preferentially occupied by the conventional ions, whereas its periphery contains the bulky counterions.

The role of PhoP/PhoQ two component system in regulating stress adaptation in Cronobacter sakazakii

2021 ◽  
pp. 103851
Author(s):  
Yan Ma ◽  
Yingying Zhang ◽  
Ke Chen ◽  
Lingzhu Zhang ◽  
Yibei Zhang ◽  
...  
Keyword(s):  
Stress Adaptation ◽  
Cronobacter Sakazakii ◽  
Two Component System ◽  
Component System ◽  
Two Component

The two-component system ActJK is involved in acid stress tolerance and symbiosis in Sinorhizobium meliloti

2021 ◽  
Vol 329 ◽  
pp. 80-91
Author(s):  
Francisco J. Albicoro ◽  
Walter O. Draghi ◽  
María C. Martini ◽  
María E. Salas ◽  
G.A. Torres Tejerizo ◽  
...  
Keyword(s):  
Stress Tolerance ◽  
Sinorhizobium Meliloti ◽  
Acid Stress ◽  
Two Component System ◽  
Component System ◽  
Two Component
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