Le transport d’ions et de molécules à l’intérieur de canaux nanométriques diffère du transport à l’échelle micro- ou macroscopique du fait de rapports surface/volume bien plus élevés conduisant à de nouveaux phénomènes de transport. Les nanotubes de carbone avec leurs propriétés uniques apparaissent comme des canaux exceptionnellement intéressants pour mieux comprendre le transport ionique et fluidique à l’échelle nanométrique et pour d’éventuelles applications nanofluidiques. Ce travail est dédié à l’étude et la compréhension des mécanismes de transport des ions en phase aqueuse à l’intérieur de nanotubes de carbone, un sujet particulièrement important pour le développement d’applications dans le domaine du séquençage de l’ADN ou de l’analyse biochimique de petites molécules.Durant ce travail, un protocole a été développé pour la fabrication de dispositifs microfluidiques intégrant des nanotubes de carbone et permettant des mesures à la fois électriques et optiques. Les propriétés de transport à l’intérieur de nanotubes de carbone mono-feuillets ont été étudiées en combinant mesures de courant ionique sous application d’un champ électrique, spectroscopie Raman et modélisation théorique. Les résultats obtenus par cette étude démontrent la forte influence de l’environnement du nanotube sur la densité et la distribution des charges de surface et donc sur les propriétés de transport à l’intérieur de ces nano-canaux dont les parois sont d’épaisseur atomique. Les ordres de grandeur des courants ioniques mesurés expérimentalement sont en bon accord avec les modèles standards de transport ionique dans un nanocanal en considérant des densités de charge de surface et des longueurs de glissement physiquement raisonnables. De manière importante, ce travail a permis de mettre en évidence un transport ionique activé par champ électrique à l’intérieur de nanotubes de carbone, qui peut être expliqué en considérant un modèle de transport plus élaboré intégrant une ou plusieurs barrières d’énergie le long du nanotube. Les résultats de la caractérisation Raman suggèrent que ces barrières d’énergie résultent d’un dopage hétérogène le long du nanotube induit par la matrice polymère. / Ionic and molecular transport inside nanometer scale geometries is distinct from micro- and macroscale transport due to the large surface-to-volume ratios which lead to unique transport phenomena. Carbon nanotubes with their peerless properties appear as exceptional channels for understanding fluidic and ionic transport at the nanoscale and for developing nanofluidics-based applications. This work is devoted at studying and understanding the transport mechanisms of ions in aqueous phase through carbon nanotubes, which is especially important for various applications such as DNA sequencing or biochemical analysis of small molecules.During this work, a protocol was developed for the fabrication of carbon nanotubes-based microfluidic devices which are suitable for both electrical and optical measurements. The transport properties through single-walled carbon nanotubes were investigated by combining ion current measurements under an applied voltage, Raman spectroscopy and theoretical modelling. The results obtained from this study highlight the strong influence of the nanotube environment on their surface charge density and distribution and hence on the ionic transport properties through these nanochannels having walls of atomic thickness. The orders of magnitude of the ionic currents experimentally measured are in good agreement with the standard models of ion transport through nanochannels when considering physically reasonable values of surface charge densities and slip lengths. Importantly, this work allowed us to evidence a novel voltage-activated transport of ions through carbon nanotubes which can be accounted for by considering a more elaborate transport model including the presence of one or more energy barriers along the nanotube. Raman characterization results support that these energy barriers result from a heterogeneous doping along the nanotubes induced by the polymer matrix.

This thesis deals with ionic liquids, their conductivity and the action of the electrode materials, separators and current collectors. The theoretical part is focused on the properties of ionic liquids, Li-ion batteries, corrosion, conductivity and analysis elements. The practical part is focused on the production of graphite electrodes, measuring the conductivity of ionic liquids with different parts of lithium – ion battery and measuring the potential window. Also, there is the effect of ionic liquids described in these parts.

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Mobile application development has become an important part of modern software development. Developers today are faced with the challenge of selecting correct frameworks to use. This thesis analyses the comparison of two JavaScript frameworks, React Native and Ionic and the guidelines on how to choose a framework based on four chosen criteria. These criteria are performance, available extensions, community support and development ability. The thesis tackles the problem of the lack of concrete guidelines for software professionals to evaluate and compare mobile application frameworks. The purpose of this thesis is to create a version of guidelines to evaluate and compare two mobile application frameworks. This version is being built upon the researcher’s study of React Native and Ionic. The goal for this thesis is that this version of guidelines could provide a basis for a software community, both researchers and practitioners, to extend the guidelines to cover more frameworks. This research aims to provide readers with a thorough grasp of the advantages and disadvantages of each framework by carefully assessing their benefits and drawbacks, enabling them to choose between React Native and Ionic in a strategic manner. A qualitative research method with support of quantitative data is used to evaluate the results. Through the process of gathering quantitative data, a comparative approach is also evaluated, comparing React Native and Ionic. When examining these two frameworks, the finding is that both are excellent choices for application development, but the optimal framework depends on the specific criteria used, as each criterion may favor one framework over the other. The findings for this thesis reveal that React Native outperforms Ionic in all of the four criteria. Through the process of evaluating each of the four criteria, the GE-MAF guidelines were formulated. / Mobilapplikationsutveckling har blivit en viktig del av modern mjukvaruutveckling. Utvecklare idag står inför utmaningen att välja rätt ramverk att använda. Detta examensarbete analyserar jämförelsen av två JavaScript-ramverk, React Native och Ionic och riktlinjerna för hur man väljer ett ramverk baserat på fyra valda kriterier. Dessa kriterier är prestanda, tillgängliga tillägg, gemenskapsstöd och utvecklingsförmåga. Avhandlingen tar upp problemet med bristen på konkreta riktlinjer för programvaruproffs att utvärdera och jämföra ramverk för mobila applikationer. Syftet med denna uppsats är att skapa en version av riktlinjer för att utvärdera och jämför två ramverk för mobila applikationer. Denna version bygger på forskarens studie av React Native och Ionic. Målet för detta examensarbete är att denna version av riktlinjerna skulle kunna ge en grund för en mjukvarugemenskap, både forskare och praktiker, att utöka riktlinjerna till att omfatta fler ramverk. Denna forskning syftar till att ge läsarna ett grundligt grepp om fördelarna och nackdelarna med varje ramverk genom att noggrant utvärdera deras fördelar och nackdelar, vilket gör det möjligt för dem att välja mellan React Native och Ionic på ett strategiskt sätt. En kvalitativ forskningsmetod med stöd av kvantitativ data används för att utvärdera resultaten. Genom processen att samla in kvantitativa data utvärderas också ett jämförande tillvägagångssätt, som jämför React Native och Ionic. När man undersöker dessa två ramverk är upptäckten att båda är utmärkta val för applikationsutveckling, men det optimala ramverket beror på de specifika kriterier som används, eftersom varje kriterium kan gynna ett ramverk framför det andra. Resultaten för denna avhandling avslöjar att React Native överträffar Ionic i alla de fyra kriterierna. Genom processen att utvärdera vart och ett av de fyra kriterierna formulerades GE-MAF:s riktlinjer.

Pharmaceutical companies and FDA (Federal Drug Administration) rules rely heavily on crystalline active pharmaceutical ingredients delivered as tablets and powders in the form of neutral compounds, salts and solvates of neutral compounds and salts. About half of all drugs sold in the market are in the form of salts which are held together by ionic bonds along with some other forces. Recently, Ionic liquids (ILs) an interesting class of chemical compounds have offered potential opportunity for exploration as novel drug ionic liquid salts, particularly in the field of transdermal/topical drug delivery. Due to the multifunctional nature of these salts they could allow generation of new pathway to manipulate the transport and deposition behaviour of the drug molecule. It is this modular approach of IL that forms the basis of the research presented here, in which pharmaceutically acceptable compounds are combined with selected drugs with known problems. IL salts were generated by combining at least one drug molecule with FDA approved compounds and were assessed for physicochemical properties, skin deposition and permeation studies. Skin deposition data suggested that these systems exhibit high skin retention, which was found to correlate with the molecular weight. On the other hand, permeation data displayed an inverse relationship between flux values and molecular weight of the permeant. Similar work was extended with ILs with mixed anions containing two drugs. The benzalkonium-sulfacetamide ILs were investigated for synergism and the biological studies data display no synergistic effect. It was also illustrated that in-situ IL based ibuprofen hydrogels systems could be manipulated via IL approach for topical application. These findings suggest the potential applicability of IL based formulations for topical delivery of drugs.

The objective of this research is to explore the use of ionic liquds in crystal engineering and drug delivery. Ionic liquids have a wide range of applications in pharmaceutical field due to their unique physicochemical propertie ssuch as chemical, thermal stability, low melting point, nonvolatility, nonflamability, low toxicity and recyclability which offer unique and interesting potential for pharmaceuitcal applications. Currently, many research groups are working on the development of ionic liquids to use in this field but there is need to develop systematic understanding about new techniques for synthesis and applications of ionic liquids to obtain new crystal form and potential of drug ionic salts. The synthesis of fifteen phosphonium ionic liquids under microwave irradiation and their physicochemical properties was investigated. The reaction time was significantly reduced compared to conventional methods, and higher yields were reported. The crystallisation of pharmaceutical drugs such as sulfathiazole, chlorpropamide, phenobarbital and nifedipine were investigated using imidazolium ionic liquids. The supramolecular complex of sulfathiazole and phenobarbital with imidazolium ionic liquids and polymorphic change in chlorpropamide was achieved. The ionic liquids provides unique environment for the crystallisation. The imidazolium salts of ibuprofen and diclofenac were synthesised and evaluated for physicochemical properties and their pharmaceutical performances especially transdermal absorption. The investigation of physicochemcal properties and pharmaceutical performance of imidazolium drug salts indicated opportunity to optimise lipophilicity and other physicochemical properties such as molecular size, osmolality, viscosity to achieve desired skin deposition and permeation. This study will provide a new approach to design of new drug salts develop using the interdisciplinary knowledge of chemical synthesis and drug delivery. / Social Justice Department, Government of Maharashtra, India.

This thesis explores the structures and dynamics of optically confined matter, ranging from single particle traps to complex optically bound colloidal arrays, investigating and quantifying the behaviour of each system. It begins with an introduction to optical manipulation techniques and a discussion of the development of the single beam gradient force trap, more commonly referred to as optical tweezers. Following this, the building of a single beam optical trap will be presented alongside a discussion of some of the key components in such a setup, before it is calibrated, allowing a demonstration of some of the techniques which are utilised later in the thesis. The optical trapping of aerosol droplets is an area of key importance in atmospheric chemistry, as optical tweezers provide a valuable and versatile tool for droplet manipulation and characterisation. Trapping single aerosol droplets is facilitated by using annular rather than conventional Gaussian beams, as will be demonstrated, with significant advantages in increasing the size range of trappable droplets, and improving their axial localisation. These improvements will be demonstrated experimentally with an in-depth comparison of Gaussian and annular beam trapping. These enhancements are also verified theoretically using a model developed by Burnham and McGloin, showing excellent agreement with experimental results. Ionic liquids, defined as organic salts with melting points below room temperature, are another area of great contemporary interest. They are highly tunable and so have been referred to as "designer solvents", and also have important applications as "green" solvents in organic chemistry. Trapping particles within these novel liquids allows a micro-rheological investigation of their properties to be conducted. This is demonstrated by determining the temperature dependent viscosity changes of these media, showing excellent agreement with previous macro-rheological studies. In addition, hydrodynamic effects such as Faxen's correction to viscous drag in proximity to a surface, and hydrodynamic coupling between pairs of colloids trapped in ionic liquids are demonstrated. Following these single and dual particle studies, this thesis continues with an investigation of the structures and dynamics of optically bound matter formed of larger numbers of particles. The behaviour of these optically bound structures is particularly sensitive to the number of particles involved, and so a counter-propagating evanescent field trap in conjunction with an inverted optical tweezers setup is utilised in order to controllably assemble these structures and study the factors affecting their behaviour. Initially one-dimensional chains of optically bound 3.5 um diameter silica particles are studied, allowing an implementation of Generalized Lorentz-Mie Theory (GLMT) to be developed through collaboration with Dr. Jonathan Taylor of The University of Glasgow. Experimental and theoretical insights allow further understanding of the processes involved in the formation of these structures. Having studied the behaviour of 3.5 um diameter silica particles in a counter-propagating evanescent wave trap, the effects of changing particle size and refractive index are presented by using smaller silica and melamine particles. These results are explained in terms of the increased importance of interference fringes in determining the arrangement of the optically bound structures of smaller particles, and due to the increased interaction of the melamine particles with the evanescent field as a result of the larger refractive index contrast between them and the trapping medium. The thesis then concludes with a study of the dynamics of the previously presented optically bound chains. Initially the diffusion of single particles in the evanescent field is compared to their freely-diffusing behaviour, quantifying the confining effect of the field. The addition of particles to the field then allows the diffusive behaviour to be studied as a function of particle number, and understood in terms of on-axis confinement by adjacent particles. The tilting of these optically bound chains relative to the inter-beam axis is also explored as a function of particle number, as is the rigidity of these chains. Finally a more complex, dynamic effect is presented, dubbed "Newton's Cradle", in which particles are ejected from the ends of the chains before returning and repeating this process. This behaviour is understood by utilising the previously developed GLMT simulations.

Thesis (MScAgric (Soil Science))--University of Stellenbosch, 2007. / Two–thirds of South Africa, including more than 280 towns and settlements are largely dependent on groundwater for their drinking water supply and development. However, groundwater resources in South Africa are limited both in terms of quantity and quality, especially in the semi–arid parts of the country (Sililo et al., 2001, p. i). Therefore, the importance of protecting groundwater resources from pollution has been recognized. The first objective of this research was to investigate the attenuation capacity of a selection of soil horizons and materials representing major types of diagnostic horizons and materials in the South African soil classification in order to validate their chemical attenuation ratings as provisionally specified by Sililo et al. (2001, p. 4.6). The second objective was to assess the pollutant attenuation capacity of South African soil horizons and materials as well as describe the diagnostic value of key chemical properties of soils for conveying information on their contaminant transport/attenuation potential. The third objective was to investigate whether it is possible to apply acid/base priming using H2SO4 and Ca(OH)2 to a bulk quantity of soil in order to reduce the mobility of contaminants.

The use of ionic liquids (ILs) as both reagents and solvents is widely recognised. ILs offer a number of advantages compared to regular molecular solvents. These advantages include: chemical and thermal stability, no measurable vapour pressure, no or lower toxicity, non-flammability, catalytic ability, high polarity and they can be recycled. There are a number of research groups investigating the various applications of this reaction medium and most studies have focused on solvents derived from the imidazolium cation. The use of the imidazolium-based ILs in the Diels-Alder reaction has been studied in detail and higher yields compared to conventional methods have been reported. The IL affects the rate and interesting selectivities have been observed. However, not much attention has been paid to the scope and limitations of phosphonium ILs (PILs). Therefore the focus of this thesis is the synthesis and application of novel chiral PILs as environmentally benign, task-specific solvents for the Diels-Alder reaction. In addition, this research seeks alternative ways to eliminate the use of toxic heavy metal catalysts and to exploit methodologies which reduce the energy consumption of the Diels-Alder reaction. A series of CILs were synthesised from the chiral pool and they were characterised by thermogravimetric analysis, differential scanning calorimetry and spectroscopy. They were then investigated as solvents and catalysts in the Diels-Alder reactions of a series of dienes (cyclopentadiene, isoprene, 2,3-dimethylbuta-1,3-diene, furan, pyrrole, N-methyl pyrrole) and dienophiles (methyl acrylate, methyl vinyl ketone, acrylonitrile, dimethyl maleate, acrolein, dimethylacetylene dicarboxylate, maleic anhydride and maleimide). Investigation of the effect of PILs in the presence of three heterogeneous catalysts Al2O3, SiO2 and K-10 montmorillonite were studied. Ultrasound and microwave-assisted Diels-Alder reactions in the PILs, in the absence and presence of the catalysts, were also studied. The reactions of these prototypical substrates illustrated that the solvents are indeed task-specific.

This dissertation serves to study a protein's conformation-function relationship since immobilized proteins often behave differently from their solution-state counterparts. Therefore, this study is important to the application of protein-based biodevices. Another aim of this dissertation is to explore a new approach to realize low voltage electrowetting without the help of oil bath. Utilizing this approach, a protein micro-separation was realized. Additionally, the interfacial properties of ionic liquid (IL) solid-like layer, which played a key role in electrowetting, was studied for further developments of IL-based applications. Atomic Force Microscopy (AFM) was utilized in the study and played multiple roles in this dissertation. First, AFM was used as a fabrication tool. In the contact mode, conductive AFM tip was used to conduct the electrochemical oxidation to create a chemical pattern or to conduct an electrowetting experiment. Subsequently, AFM was used as a characterization tool in the tapping mode to characterize the surface structure, the thickness, and the surface potential. Furthermore, AFM in the contact mode was used as a measurement tool to measure the tribological force properties of sample. The results of the study concerning the conformational change in immobilized calmodulin showed that the immobilized CaM retained its activity. Additionally, the immobilization of CaM on a solid support did not interfere with the ability of the protein to bind calcium, as well as CaM kinase binding domain. For the electrowetting experiment, our data suggested that the ultra-high capacitance density of the IL dielectric layer leads to the low voltage electrowetting. We also successfully demonstrated the streptavidin and GFP proteins separation by Electrowetting-on-Dielectric (EWOD) force. The results of the surface properties study indicated that the charge and dipole of the substrate can influence the structures and properties of the IL interfacial layer. Our study would be beneficial in research and assay work involving engineered proteins, as well as the study and development of electrowetting applications.