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415 results on '"Samsuzzaman, Md"'

1. Flow Of Information In a Mechanically Quenched Confined Flock

Author

Samsuzzaman, Md., Hasanuzzaman, Mohammad, Sayeed, Ahmed, and Saha, Arnab

Subjects
Physics - Biological Physics, Condensed Matter - Soft Condensed Matter, Condensed Matter - Statistical Mechanics
Abstract

Living entities in a group communicate and transfer information to one another for a variety of reasons. It might be for foraging food, migration, or escaping threats and obstacles, etc. They do so by interacting with each other and also with the environment. The tools from statistical mechanics and information theory can be useful to analyze the flow of information among the living entities modelled as active (i.e. self-propelling) particles. Here we consider the active particles confined in a circular trap. The self-organisation of the particles crucially depends on whether the trap boundary is soft or hard. We quench the trap boundary from soft to hard instantaneously. After the mechanical quench, the particles suddenly find themselves in a hard potential. The self-organised cluster of the active particles, which was stable when the boundary was soft, becomes unstable. The cluster undergoes extreme deformation after the quench to find another stable configuration suitable for the hard potential. Together with the structural relaxation, information regarding the quench also flows throughout the deforming cluster. Here, we quantify the flow of information by computing local transfer entropy. We find that the flow spans the whole cluster, propagating ballistically.

Published
2024

2. Stochastic Heat Engine Using Multiple Interacting Active Particles

Author

Kumari, Aradhana, Samsuzzaman, Md, Saha, Arnab, and Lahiri, Sourabh

Subjects
Condensed Matter - Statistical Mechanics
Abstract

The area of stochastic heat engines using active particles has attracted a lot of attention recently. They have been shown to exhibit advantages over engines using passive particles. In this work, we use multiple self-propelling particles undergoing Vicsek-like aligning interaction as our working system. The particles are confined in a two-dimensional circular trap. The interplay between the confinement and the activity of the particles induces clustering. These clusters change their locations relative to the walls of the trap, when the wall steepness is varied with time. In this work we demonstrate that changing the steepness of the wall and the activity of the particles time-periodically can cause the system to act as an engine. In this setup, we study the variations in extracted work with the activity, rotational diffusion, and the Vicsek radius of individual particles. We also comment on the complications involved in the definition of the engine efficiency in accordance with the usual prescription of stochastic thermodynamics., Comment: 13 pages, 8 figures

Published
2023

15. Reentrant Melting of Lanes of Rough Circular Discs

Author

Samsuzzaman, Md., Sayeed, A., and Saha, Arnab

Subjects
Condensed Matter - Soft Condensed Matter
Abstract

We consider binary suspension of rough, circular particles in two dimensions under athermal conditions. The mean density of the system is kept constant. The suspension is subject to a time-independent external drive in response to which one half of the particles are pulled along the field direction whereas the other half is pushed in the opposite direction. Simulating the system with different magnitude of external drive in steady state, we obtain oppositely moving macroscopic lanes only for a moderate range of external drive. Below as well as above the range we obtain states with no lane. Hence we find that no-lane state re-enters along the axis of the external drive in the non-equilibrium phase diagram corresponding to the laning transition, with varying roughness of individual particles and external drive. Inter-particle friction (contact dissipation) due to the roughness of the individual particle is the main player behind the re-entrance of no-lane state at high external drives., Comment: First Version

Published
2021

23. Tuning Self Organization Of Confined Active Particles By Steepness Of The Trap

Author

Rana, Shubhashis, Samsuzzaman, Md., and Saha, Arnab

Subjects
Condensed Matter - Soft Condensed Matter, Condensed Matter - Statistical Mechanics
Abstract

We consider collective dynamics of self-propelling particles in two dimensions. They can align themselves according to the direction of propulsion of their neighbours, together with a random perturbation (i.e. rotational fluctuation). They are also interacting with each other by a soft, isotropic, excluded-volume interaction. Particles are confined in a circular trap. The steepness of the trap is tuneable. Their average packing fraction and strength of rotational fluctuation are low. When the trap is steep, particles flock along its boundary. They form polar cluster that spreads over the boundary. The cluster has no spatial or structural order. We show, when the steepness is decreased beyond a threshold value, the clusters become round, compact and eventually spatial order (hexagonal) emerges in addition to the pre-established polar order within them. We investigate kinetics of such ordering. We find that while rotating around the centre of the trap along its circular boundary, the clusters need to roll around their centre of mass, to be spatially ordered. We also discuss the stability of the order when the trap is suddenly switched off.

Published
2019

48. A Synthetic Derivative SH 66 of Homoisoflavonoid from Liliaceae Exhibits Anti-Neuroinflammatory Activity against LPS-Induced Microglial Cells.

Author

Samsuzzaman, Md, Subedi, Lalita, Seong-Min, Sanha Lee, Gaire, Bhakta Prasad, Eun-Ji Ko, Ji-Woong Choi, Seung-Yong Seo, and Sun-Yeou Kim

Abstract

Naturally occurring homoisoflavonoids isolated from some Liliaceae plants have been reported to have diverse biological activities (e.g., antioxidant, anti-inflammatory, and anti-angiogenic effects). The exact mechanism by which homoisoflavonones exert anti-neuroinflammatory effects against activated microglia-induced inflammatory cascades has not been well studied. Here, we aimed to explore the mechanism of homoisoflavonoid SH66 having a potential anti-inflammatory effect in lipopolysaccharide (LPS)-primed BV2 murine microglial cells. Microglia cells were pre-treated with SH66 followed by LPS (100 ng/mL) activation. SH66 treatment attenuated the production of inflammatory mediators, including nitric oxide and proinflammatory cytokines, by down-regulating mitogen-activated protein kinase signaling in LPS-activated microglia. The SH66-mediated inhibition of the nucleotide-binding oligomerization domain-like receptor family pyrin domain containing 3 (NLRP3) inflammasome complex and the respective inflammatory biomarker-like active interleukin (IL)-1β were noted to be one of the key pathways of the anti-inflammatory effect. In addition, SH66 increased the neurite length in the N2a neuronal cell and the level of nerve growth factor in the C6 astrocyte cell. Our results demonstrated the anti-neuroinflammatory effect of SH66 against LPS-activated microglia-mediated inflammatory events by down-regulating the NLRP3 inflammasome complex, with respect to its neuroprotective effect. SH66 could be an interesting candidate for further research and development regarding prophylactics and therapeutics for inflammation-mediated neurological complications. [ABSTRACT FROM AUTHOR]

Published
2024
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