High-Temperature Collision Integrals for m-6-8 and Hulburt–Hirschfelder Potentials

This study is aimed to determine collision integrals for atoms interacting according to the m-6-8 and Hulburt–Hirschfelder potentials and analyze the differences between potentials. The precision of four significant digits was reached at all tested temperatures, and for high-temperature applications, six digits were calculated. The proposed method was tested on the Lennard-Jones potential and found to excellently agree with the recent high-quality data. In addition, the Hulburt–Hirschfelder potential was used for determining the collision integrals of the interaction of nitrogen atoms in the ground electronic state and compared with other known values. The calculations were performed using Mathematica computation system which can deal with singularities (so-called orbiting).

Molecular diffusion in gases and liquids

The diffusion coefficients in gases and liquids calculated by the molecular dynamics method with the use of the hard absolutely rough elastic spheres model are compared with those calculated using the Lennard-Jones potential. It is shown that dependences of reduced diffusion coefficients on density are similar, but differ numerically for different intermolecular interaction models. The simulation results have been compared with the experimental data on the diffusion in gaseous and liquid argon and in liquid benzene.

Effect of Impurities on a Two-Dimensional Dodecagonal Quasicrystal

Langevin dynamics simulations are performed to examine how impurities affect two-dimensional dodecagonal quasicrystals. We assumed that the interaction potential between two particles is the Lennard-Jones-Gauss potential if at least one of these particles is a matrix particle and that the interaction potential between two impurities is the Lennard-Jones potential. Matrix particles and impurities impinge with constant rates on the substrate created by a part of a dodecagonal quasicrystal consisting of square and triangular tiles. The dependences of the twelve-fold rotational order and the number of shield-like tiles on the impurity density are examined after sufficient solid layers are grown. While the change in the twelve-fold rotational symmetry is small, the number of shield-like tiles in the solid increases greatly with increasing impurity density.

The effect of temperature and pressure on nitrogen adsorption in amorphous silica

Nitrogen is an element that is widely found in nature can be used as a gas that is absorbed to help characterize materials, especially on the surface of the material. According to Brunauer – Emmet - Teller (BET) is a theory where nitrogen is used as a gas characterizing material because of its ability to high purity and can interact with solid elements and inert. BET can only produce quantitative data and does not show adsorption phenomena. Molecular dynamics simulation is conducted to observe the phenomena during nitrogen adsorption in amorphous silica, a porous material with a large surface area. In this study, the molecular dynamics simulations are arranged in a state of isotherm, where the temperature used is three variables: 77 K, 100 K, and 150 K in the variation of pressure used 1, 3, 5, 7, and 10 atm for each equilibrium. In molecular dynamics simulation to simulate the interaction between atoms based on Coulomb force is using Lennard-Jones Potential. Based on the simulation results obtain, it was found that at 77 K temperature had the optimal ability to adsorb nitrogen compared to 100 K and 150 K. The higher the pressure given in the system, it will increase the amount of nitrogen adsorbed.

The Size and Shape Effects on the Melting Point of Nanoparticles Based on the Lennard-Jones Potential Function

A model is proposed to calculate the melting points of nanoparticles based on the Lennard-Jones (L-J) potential function. The effects of the size, the shape, and the atomic volume and surface packing of the nanoparticles are considered in the model. The model, based on the L-J potential function for spherical nanoparticles, agrees with the experimental values of gold (Au) and lead (Pb) nanoparticles. The model, based on the L-J potential function, is consistent with Qi and Wang’s model that predicts the Gibbs-Thompson relation. Moreover, the model based on the non-integer L-J potential function can be used to predict the melting points of nanoparticles.

Self-Assembly of Porous Structures From a Binary Mixture of Lobed Patchy Particles

We report simulation studies on the self-assembly of a binary mixture of snowman and dumbbell shaped lobed particles. Depending on the lobe size and temperature, different types of self-assembled structures (random aggregates, spherical aggregates, liquid droplets, amorphous wire-like structures, amorphous ring structures, crystalline structures) are observed. At lower temperatures, heterogeneous structures are formed for lobed particles of both shapes. At higher temperatures, homogeneous self-assembled structures are formed mainly by the dumbbell shaped particles, while the snowman shaped particles remain in a dissociated state. We also investigated the porosities of self-assembled structures. The pore diameters in self-assemblies increased with an increase in temperature for a given lobe size. The particles having smaller lobes produced structures with larger pores than the particles having larger lobes. We further investigated the effect of σ, a parameter in the surface-shifted Lennard-Jones potential, on the self-assembled morphologies and their porosities. The self-assembled structures formed at a higher σ value are found to produce larger pores than those at a lower σ.

Continuum Modelling for Encapsulation of Anticancer Drugs inside Nanotubes

Nanotubes, such as those made of carbon, silicon, and boron nitride, have attracted tremendous interest in the research community and represent the starting point for the development of nanotechnology. In the current study, the use of nanotubes as a means of drug delivery and, more specifically, for cancer therapy, is investigated. Using traditional applied mathematical modelling, I derive explicit analytical expressions to understand the encapsulation behaviour of drug molecules into different types of single-walled nanotubes. The interaction energies between three anticancer drugs, namely, cisplatin, carboplatin, and doxorubicin, and the nanotubes are observed by adopting the Lennard–Jones potential function together with the continuum approach. This study is focused on determining a favourable size and an appropriate type of nanotube to encapsulate anticancer drugs. The results indicate that the drug molecules with a large size tend to be located inside a large nanotube and that encapsulation depends on the radius and type of the tube. For the three nanotubes used to encapsulate drugs, the results show that the nanotube radius must be at least 5.493 Å for cisplatin, 6.452 Å for carboplatin, and 10.208 Å for doxorubicin, and the appropriate type to encapsulate drugs is the boron nitride nanotube. There are some advantages to using different types of nanotubes as a means of drug delivery, such as improved chemical stability, reduced synthesis costs, and improved biocompatibility.