A close-packed sphere model for characterising porous networks in atomistic simulations and its application in energy storage and conversion

Hierarchical (micro, meso & macro) porosity in materials plays a crucial role in influencing the movement of ions which governs the energy and power density during energy storage and conversion. The extant available methods to characterise porosity across scales (nano to meso to macro) lacks rigour and accuracy. Having accurate assessment of the porosity in materials can unlock new designs of electrodes for energy efficient energy storage and conversion devices such as batteries, supercapacitors and fuel cells. Through this work, we report the systematic development of a method to fully characterise the carbon porous networks using a molecular dynamics simulation testbed. Our work entails modelling and simulation of porous carbon structures using quenched molecular dynamics (QMD) simulations using Gaussian Approximation potential (GAP) and benchmarking the results with prior literature. This modelling technique can reliably be used for quantitative characterisation of the interconnectivity in porous structures to study ionic movements and charge transfer mechanisms. A new parameter, namely nearest neighbour search (NNS) coefficient was introduced to quantify homogeneity and networking in the porous structures. NNS coefficient increased from 1.62 to 1.92 with decrease of the annealing temperature from 8000 K to 4000 K in carbon. The procedure outlined was although tested on porous carbon networks, but adaptable to study any other material system at multi-length scales

Development of mucoadhesive sprayable gellan gum fluid gels

The nasal mucosa provides a potentially good route for local and systemic drug delivery. However, the protective feature of the nasal cavity make intranasal delivery challenging. The application of mucoadhesive polymers in nasal drug delivery systems enhances the retention of the dosage form in the nasal cavity. Several groups have investigated using low acyl gellan as a drug delivery vehicle but only limited research however, has been performed on high acyl gellan for this purpose, despite its properties being more conducive to mucoadhesion. High acyl gellan produces highly elastic gels below 60 °C which make it difficult to spray using a mechanical spray device. Therefore, in this study we have tried to address this problem by making fluid gels by introducing a shear force during gelation of the gellan polymer. These fluid gel systems contain gelled micro-particles suspended in a solution of un-gelled polymer. These systems can therefore behave as pourable viscoelastic fluids. In this study we have investigated the rheological behavior and mucoadhesion of fluid gels of two different types of gellan (high and low acyl) and fluid gels prepared from blends of high and low acyl gellan at a 50:50 ratio. The results demonstrated that by preparing fluid gels of high acyl gellan, the rheological properties were sufficient to spray through a standard nasal spray device. Moreover fluid gels also significantly enhance both high acyl and low acyl gellan mucoadhesion properties

Thermo-physical characteristics of 3C-SiC structure subjected to microwave exposure: A molecular dynamics study

Silicon carbide (SiC) is widely used as a susceptor for microwave hybrid heating applications owing to its exceptional microwave absorbing characteristics. In practice, it is challenging to characterize the thermo-physical behaviour of the microwave irradiated SiC-based targets experimentally due to interference of integrated measurement devices with microwaves. In this article, molecular dynamics simulations were performed to understand the atomistic response of a bulk 3C-SiC model during microwave heating. Atomistic simulations were performed at different electric field strengths (ranging from 0.1 to 0.5 V/Å) and frequencies (ranging from 100 to 500 GHz) to develop a numerical relationship between temperature and time in order to predict the thermal response of bulk 3C-SiC. On the other hand, the physical characteristics of the bulk 3C-SiC were determined by the plots between mean square displacement (MSD), time and diffusion coefficients. The results showed that at 0.5 V/Å electric field strength and 500 GHz frequency, the diffusion coefficient increased up to 88% as compared to the electric field strength of 0.1 V/Å at 500 GHz. A change of 75% in the physical phase of 3C-SiC structure with respect to the initial structure was confirmed by the distorted density distribution profil

Thermo-physical characteristics of 3C-SiC structure subjected to microwave exposure: A molecular dynamics study

Silicon carbide (SiC) is widely used as a susceptor for microwave hybrid heating applications owing to its exceptional microwave absorbing characteristics. In practice, it is challenging to characterize the thermo-physical behaviour of the microwave irradiated SiC-based targets experimentally due to interference of integrated measurement devices with microwaves. In this article, molecular dynamics simulations were performed to understand the atomistic response of a bulk 3C-SiC model during microwave heating. Atomistic simulations were performed at different electric field strengths (ranging from 0.1 to 0.5 V/Å) and frequencies (ranging from 100 to 500 GHz) to develop a numerical relationship between temperature and time in order to predict the thermal response of bulk 3C-SiC. On the other hand, the physical characteristics of the bulk 3C-SiC were determined by the plots between mean square displacement (MSD), time and diffusion coefficients. The results showed that at 0.5 V/Å electric field strength and 500 GHz frequency, the diffusion coefficient increased up to 88% as compared to the electric field strength of 0.1 V/Å at 500 GHz. A change of 75% in the physical phase of 3C-SiC structure with respect to the initial structure was confirmed by the distorted density distribution profile