In this work, silver nanoparticles (AgNPs) were synthesized quickly and in an eco-friendly manner using the extract of Mulberry leaves and aqueous solution of silver nitrate without any toxic chemicals (Yuet et al. Int. J. Nanomed. 2012, 7, 4263–4267; Krishnakuma and Adavallan. Adv. Nat. Sci. Nanosci. Nanotechnol. 2014, 5, 025018). The Mulberry leaves extract functions as both a stabilizing and reducing agent. The UV-Vis spectroscopy shows a peak maximum at 430 nm. The transmission electron microscopy (TEM) image illustrated of synthesized AgNPs were nearly spherical-shaped particles whose sizes range from 15 to 20 nm. The TEM image of Nano Silver solution sample synthesized by the microwave assisted method shows nearly spherical particles, with an average particle size estimated at 10 nm. The absorption UV-vis spectrum of silver nanoparticles synthesized by the microwave assisted method (AgNPsmw) shows a sharp absorption band around 415 nm. The UV-Vis spectrum of AgNPsmw after two months of storage shows negligible peak changes of silver nanoparticles.

The nature of the phase transition in a system of self-propelling particles has been extensively studied during the past few decades. A theoretical model was proposed by [T. Vicsek et al. Phys. Rev. Lett. 75, 1226 (1995)] with a simple rule for updating the direction of motion of each particle. Based on the model of Vicsek et al., in this paper, we consider a group of animals as particles moving freely in a two-dimensional space. Due to the fact that the viewable area of animals depends on the species, we consider the motion of each individual within an angle $\phi =\varphi /2$ $(\varphi$ is called the angle of view) of a circle centered at its position of radius $R$. We obtained a phase diagram in the space $\left(\phi ,{\eta }_c\right)$ with ${\eta }_c$ being the critical noise. We show that the phase transition exists only in the case of a wide view's angle $\phi \ge 0.5\pi$. The flocking of animals is a universal behavior of the species of prey but not the one of the predator. Our simulation results are in good agreement with experimental observation [C. Beccoa et al., Physica A 367, 487 (2006)].

This work aims at investigating the effect of surface charge sign on static and dynamic properties of aqueous solutions confined in the charged nanochannel. Molecular dynamics simulations of two confinement systems have been performed, in which the nanochannel walls were modelled as the structureless walls with the uniform continuous distribution of surface charge. It is found that the sign of surface charge has a noticeable impact on the aqueous solution in a region close to the wall. The aqueous solution is more strongly layered and less translational and rotational diffusive in the positively charged nanochannel. But, the water molecules are more preferably oriented in the negatively charged nanochannel. The results have been consistently explained by microscopically analysing the forces acting atoms of water molecules and counter-ions, and the contributions into the torque acting on the water molecule.

The Vicsek’s model (VM) [T. Vicsek, et. al., Phys. Rev. Lett. 75, 1226 (1995)] is apopular approach to study nature of the phase transition of self-propelling system. In this model,the direction of motion of each particle depends on the average velocity of its neighboring particleswithin a circle of radius R. In this work, we consider a group of fishes as the particles, but weassumed that only the individuals of its neighbors within a circle sector with central angle ϕ (iscalled angle of view) and radius R, are taken into account the average direction of motion. Weused a similar model as the well known XY spin model on a square lattice of linear size L, theparticles can move freely on the plane (an off-lattice model). A phase diagram in the space (φ,ξc) has been established where φ = ϕ/2 2 [0, π] and ξc being the critical noise. We shown thatξc strongly depends on the view’s angle φ 0.5π, but slightly varies with φ < 0.5π. So, we canconclude that the schooling behavior of animal is only of the prey species, but not of the predator