Sn clathrates are promising phonon glass, electron crystal materials (PGEC), in which the phonon free paths are short and the electron free paths are long. We analysed the relaxed structure of Sn clathrates using four different Density Funtional Exchange-Correlation functionals. The phonon structures were investigated as a first step in order to determine the phonon contribution to the thermal conductivity. We determined the Seebeck coefficient and electrical conductivity of the clathrate compound and the thermoelectric figure of merit. A glimpse into the dynamics of the system for the evaluation of the thermoelectric and electronic properties is presented.

Zirconium has attracted a lot of attention recently due to its distinctive properties that make it suitable for extensive applications in the nuclear power and chemical industry. Zirconium and its alloys are undergoing long-term development as promising materials for the nuclear industry and power engineering. Recently, advanced Zr-based alloys are aimed for service in more severe operating conditions such as higher burn-up, increased operation temperature, and high-PH operation. In this work we observe the temperature dependence of Zr50Nb50, Zr78Nb22, Zr78Nb19Co3 and Zr50Nb49Sn1. It was observed that ternary additions with small atomic percentages of Co and Sn have significant impact on Zr-Nb alloy; and their elastic properties showed a possible enhancement on high temperature applications and physical strength.

Macroscopic strength of the rock depends on the behavior of the micro constituents, that is, the minerals, pores and crack profile. It is important to determine the effect of these constituents on the overall behavior of the rock. This study seeks to estimate the effective elastic properties of granite using the finite element method. A representative volume element (RVE) of suitable size with spherical inclusions of different distribution is subjected to loading and the effective elastic properties determined. The results are compared to those obtained from analytical methods. The elastic properties are obtained in both the axial and transverse direction to account for anisotropy. It is observed that there is congruence in the results obtained both analytically and numerically. The method of periodic microstructures exhibits close agreement with the numerical results.

Commuter trains with solid axle configuration are produced from medium carbon steel due to cost restrictions. High-speed trains have hollow axle configuration for reduced weight and are made from high strength low-alloy (HSLA) steels. The HSLA steels have higher amounts of C, Cr, Ni, Mo, V and Nb, and are more expensive than medium carbon steels. The effects of phase proportions, carbon equivalent (CE), yield strength and ultimate tensile strength (UTS) on material costs of existing railway axle steels were studied using Thermo-Calc. Medium carbon rail axle steels had higher Fe3C phase proportions than the HSLA steel rail axle grades. Higher affinity of Cr, Mo and V for C than Fe resulted in decreased cementite proportions. The HSLA steels had yield strengths above 370 MPa, and UTS above 750 MPa, with increased material cost above $3300 per ton. A scattered distribution was observed for the pearlite weight fraction and material costs, with most between $3200 and $3400. The yield and tensile strengths increased with increasing carbon equivalent and pearlite weight fraction. The data aided the selection and design of alloys with better mechanical and corrosion properties at reduced material cost.

Materials science is arguably the most important discipline in the physical sciences that should be developed in Africa given its rich resources of minerals, energy and biological diversity. Developing materials science should therefore be an important goal for Africa with important opportunities for economic benefits and quality people development. There are already many successful materials science activities that are underway in Africa. This needs to gain wider international attention and should become contact points for international collaborations. The African School for Electronic Structure Methods and Applications (ASESMA)[1,2,3,4] is one such successful initiative that has been in existence for the past decade. ASESMA has shown that it is possible to build a network across sub-Saharan Africa with world-class research with a relatively low budget. The greatest asset is the commitment of the lecturers and mentors, the team-work of the local organisers and the idealism of the participants who rank amongst the brightest of young minds from Africa, many of whom come from impoverished backgrounds but still dare to reach for the stars.

Background: The development of appropriate dosage forms for paediatric antiretroviral therapy is key for improved therapeutic outcomes in children. The focus of this study was to improve solubility, dissolution rate, drug release and maintain high drug permeability.

Methodology: A nanoemulsion was prepared using emulsion inversion point and evaluated. The nanoemulsion had nevirapine (3% w/w). In vitro drug release studies were performed using dialysis membrane. Permeability studies using the Caco-2 cell model were performed for the formulation.

Results: The optimized nevirapine nanoemulsion had a mean droplet size of 36.09±12.27nm, low pdI of 0.598 and zeta potential of -7.87±4.35mV. At pH 2, the nanoemulsion released 76 ± 2 % of nevirapine within 2 h, while at pH 6.4 value representing the small intestine, amount of nevirapine released was 41.6± 4 %. The permeability rate of the nevirapine nanoemulsion was 30.02 x 10-6cm/s and higher than that of propranolol. Efflux ratio was 0.02 indicating low chance of drug efflux occurring.

Conclusion: The results showed that a modified liquid drug release formulations of nevirapine could improve rate of dissolution and maintain high permeability and low drug efflux improving bioavailability of nevirapine in vivo.

In most materials, surfaces and interfaces present a significant portion of the workable area, but this area has often been erroneously perceived as a challenge in processing and thus, largely ignored. Surfaces and interfaces, however, present a network of energetically mismatched (sometimes metastable) molecules that can be exploited to either control surface reactions, engineer bulk stability or reveal new fundamental details of otherwise not well understood processes or systems as described herein. This perspective captures the role of i) structure, ii) chemistry and iii) thermodynamics at the interface in fabricating functional materials. Engineering substrate morphology enables tunable wettability either through the substrate or an adsorbed self-assembled monolayer (SAM), the latter being largely due to effect of sub-nanoscale roughness on conformational defects and overall order in the SAM. Surface roughness and chemistry also dictates the nature and amount of adventitious contaminants on a surface, and this was used to control volume of adsorbed water leading to controlled and tunable step-growth polymerization. The chemical treatment renders the paper amphiphobic, which could be used for self-cleaning surfaces and nucleation of water microdroplets for water harvesting. Finally, creating a self-passivating polished thin (∼0.7-2 nm) shell on a molten metal microdroplet kinetically frustrates solidification leading to significant undercooling. The ambient undercooled liquid metal is used for mechanically-triggered heat-free solder and smart composites. These three cases demonstrate key aspects of surface and interface engineering in integrating well-known concepts for the development of functional materials.