A novel integrated platform combining atomic force microscopy and fluorescence correlation spectroscopy

At the nanoscale near an interface, the discrete nature of liquids is expected to influence various properties, such as density, viscosity or diffusion constants. Understanding interfacial properties of liquids is important for the development of nanotechnology, especially for the fields of nano-rheology and nano-tribology, and also for understanding various mechanisms in biological systems at the molecular level, such as protein folding or the self-assembly of lipid vesicles, which invariably involve liquids. Atomic force microscope (AFM) and fluorescence correlation spectroscope (FCS) are two complimentary techniques that are commonly employed investigate mechanics and dynamics of liquids at interfaces. In this thesis, the design and construction of a novel integrated platform combining AFM and FCS is presented. The platform consists of a newly built high sensitive AFM on top of an existing custom-made FCS setup. The design is modular in nature, can be easily assembled or disassembled and thus both AFM and FCS can be used independently. The successful operation was the platform was demonstrated by employing a colloidal liquid as a test system. Results of AFM experiments indicated the presence of structure to the colloidal dispersion under confinement, similar to the behavior of molecular liquids reported in the literature, at length scales of a few 10 nm. However, FCS results showed considerable decrease in the diffusion of colloidal particle even when the confinement was of the order of microns. The design, construction and the testing of the new platform along with the intriguing results will be presented

The adoption of e-commerce in the Lesotho tourism industry

Over the years, Information and Communication Technology (ICT) has been revolutionising global markets. In developed nations, for example, there has been a push for developing countries to adopt ICT as leverage towards improving their economic development. However, in the current era, ICT adoption has not been as widespread as anticipated in some parts of the world, with its use in developing countries especially, lagging behind. This is particularly so amongst the small, medium, micro-enterprise (SMME) sector, important drivers of the economy in the developing world. SMMEs in developing countries have been hindered in the uptake of ICTs, largely due to underlying issues such as the high cost of ICT, inadequate and unreliable infrastructure, as well as lack of policy necessary to promote competition and growth within the ICT sectors

Thermal decomposition and ignition of coal

A study of the thermal decomposition and ignition of coal as functions of pelletizing pressure and dwell time has revealed that: (1) ignition and thermal behaviour are related to the apparent density of the pelletized coal; (2) for a given apparent density of pelletized coal, the ignition temperature is related to the rate constants of thermal decomposition. Isothermal decomposition in air at 550 °C has been shown to fit the Avrami-Erofeev equation for three-dimensional growth of nuclei

Stereoselective synthesis of (10S, 12S)-10-hydroxy-12-methyl-1-oxacyclododecane-2, 5-dione via Prins cyclization

The total synthesis of (10S,12S)-10-hydroxy-12-methyl-1-oxacyclododecane-2,5-dione is described proving the versatility of the Prins cyclization in natural products synthesis. The approach is convergent and highly stereoselective. Prins cyclization, esterification, ring-closing metathesis and oxidation reactions are utilized as key steps in the synthesis of this macrolactone

Change in Rigidity in the Activated Form of the Glucose/Galactose Receptor from Escherichia coli: A Phenomenon that Will Be Key to the Development of Biosensors

Recently a periplasmic glucose/galactose binding protein, GGRQ26C, immobilized on a gold surface has been used as an active part of a glucose biosensor based on quartz microbalance technique. However the nature of the glucose detection was not clear. Here we have found that the receptor protein film immobilized on the gold surface increases its rigidity when glucose is added, which explains the unexpected detection signal. To study the rigidity change, we developed a new fast and simple method based on using atomic force microscopy (AFM) in tapping mode. The method was verified by explicit measurements of the Young's modulus of the protein film by conventional AFM methods. Since there are a host of receptors that undergo structural change when activated by ligand, AFM can play a key role in the development and/or optimization of biosensors based on rigidity changes in biomolecules