Applications of Hot Melt Extrusion (HME) in pharmaceuticals have become increasingly popular over the years but nonetheless a few obstacles still remain before wide scale implementation. In many instances these improvements are related to both processing and product performance. It is observed that HME process optimisation is majorly focused on the active pharmaceutical ingredient's (API) properties. Characterising polymeric properties for their suitability in HME should be equally studied since the impact of excipients on both product and process performance is just as vital. In this work, two well-established cellulose ester derivatives: Hydroxy Propyl Methyl Cellulose Acetate Succinate (HPMCAS) and Hydroxy Propyl Methyl Cellulose Phthalate (HPMCP) are studied for their HME suitability. Their thermal, thermodynamic, rheological, thermo-chemical and degradation kinetic properties were evaluated with model plasticisers and APIs. It was found the thermal properties of HPMCP are severely compromised whereas HPMCAS is more stable in the processing zone of 150 to 200 °C. Thermodynamic properties revealed that both polymers share an important solubility parameter range (20-30 MPa P1/2P) where the majority of plasticisers and BCS class II APIs lie. Thus, greater miscibility/solubility can be expected. Further, the processability of these two polymers investigated by rheometric measurements showed HPMCAS possesses better flow properties than HPMCP because HPMCP forms a weak network of chain interactions at a molecular level. However, adding plasticisers such as PEG and TEC the flow properties of HPMCP can be tailored. The study also showed that plasticisers have a major influence on thermo-chemical and kinetic properties of polymers. For instance, PEG reduced polymer degradation with reversal in kinetic parameters whereas blends of CA produced detrimental effects and increased polymer degradation with reduction in onset degradation temperatures. Further, both polymers are observed to be chemically reactive with the APIs containing free -OH, -SOR2RN- and -NH2 groups. Finally, these properties prove that suitability of HPMCP is highly debated for HME and demands great care in use while that of HPMCAS is relatively better than HPMCP in many instances.

"The Response of African Religion to Poverty with specific reference to the Umzimkhulu Municipality" is a particular effort of the wider world that researches the ways and means for combating the scourge of poverty in society aiming at securing a better future for the future generations. In as much as African traditional religion is part of the culture, tradition and custom of its tenants, and as such aims at the wellbeing of its tenants, it is able to offer a response to poverty. It teaches about the importance of the values of community, meaningful and life-affirming relationships and the value of ubuntu. All these clamour for extended sharing and extended participation which are essential if society will continue to exist. African traditional religion maintains an ethic that says: `Real poverty results from the blockage of the vital links'. Celebrating economic achievements in food must be preceded by the celebration of people. `Batho pele': is the contemporary Democratic South Africa's slogan that suggests putting people in the center of life. It does not only call us to serve the poor, but also to allow them to champion the courses of the kind of service they desire. African traditional religion teaches that, together with the other institutions that govern the lives of people, religion and politics should have among other things a concern about production and distribution of the resources, hence the claim: `Food is also politics'. In their dealing with the problem of poverty, religion, politics and other social institutions ought to dedicate a special place to instilling positive attitudes towards the concept of work among their tenants. In this way the slogan `Batho pele' or people first, does not merely mean waiting to be served, but it also means that every body to the best of their ability ought to be doing something towards the production of the items of service. The inclusiveness of African religion in terms of what it calls `community' cautions society about the importance of the other beings in its consideration of poverty alleviation. Our economic wellbeing depends mostly on our attitude towards the other non-personal neighbours, prominent among which is our common abode, the earth, the land. / Religious Studies & Arabic / D.Th. (Religious Studies)

This thesis considers quantum impurity models that exhibit a quantum phase transition (QPT) between a Fermi liquid strong coupling (SC) phase, and a doubly-degenerate non-Fermi liquid local moment (LM) phase. We focus on what can be said from exact analytic arguments about the LM phase of these models, where the system is characterized by an SU(2) spin degree of freedom in the entire system. Conventional perturbation theory about the non-interacting limit does not hold in the non-Fermi liquid LM phase. We circumvent this problem by reformulating the perturbation theory using a so-called `two self-energy' (TSE) description, where the two self-energies may be expressed as functional derivatives of the Luttinger-Ward functional. One particular paradigmatic model that possesses a QPT between SC and LM phases is the pseudogap Anderson impurity model (PAIM). We use infinite-order perturbation theory in the interaction, U, to self-consistently deduce the exact low-energy forms of both the self-energies and propagators in each of the distinct phases of the model. We analyse the behaviour of the model approaching the QPT from each phase, focusing on the scaling of the zero-field single-particle dynamics using both analytical arguments and detailed numerical renormalization group (NRG) calculations. We also apply two `conserving' approximations to the PAIM. First, second-order self-consistent perturbation theory and second, the fluctuation exchange approximation (FLEX). Within the FLEX approximation we develop a numerical algorithm capable of self-consistently and coherently describing the QPT coming from both distinct phases. Finally, we consider a range of static spin susceptibilities that each probe the underlying QPT in response to coupling to a magnetic field.

Cette thèse est centrée sur la mesure et l'interprétation du rayonnement X mou ([1 keV; 15 keV] environ) dans les Tokamaks. Le chapitre 2 montre que ce rayonnement véhicule des informations sur la température et la densité du plasma, sur sa configuration magnétique, et sur son contenu en impuretés. Malheureusement les mesures effectuées sont intégrées spatialement et spectralement et résultent des contributions de tous les ions présents.Le diagnostic X mou de Tore Supra s'articule autour de diodes semi-conductrices présentée dans le chapitre 3 aux côté d'un détecteur à gaz testé avec succès. Une nouvelle méthode de détermination de la réponse spectrale d'un photodétecteur n'utilisant qu'un tube X mou portable est également décrite.Les inversions tomographiques, qui permettent d'accéder au champ d'émissivité reconstruit dans une section poloidale, font l'objet du chapitre 4. Les améliorations apportées à un algorithme particulier sont détaillées.Une comparaison systématique entre les positions horizontales du maximum d'émissivité et de l'axe magnétique est présentée au chapitre 5.Le chapitre 6 décrit une hypothèse concernant la résilience de la fonction de rayonnement X mou d'une impureté vis-à-vis du transport de cette impureté. Cette hypothèse permet de déduire la densité d'une impureté de son émissivité X mou. Les processus physiques justifiant cette hypothèse, ainsi que leur domaine de validité sont analysés avec soin.Le chapitre 7 présente les asymétries poloidales d'émissivité X mou. Les premiers résultats d'expériences mises en oeuvres à ASDEX-U pour vérifier les dépendences paramétriques de deux types particuliers d'asymétries sont détaillés. / This thesis focuses on measuring and interpreting the Soft X-Ray (SXR) radiation (approximately [1 keV; 15 keV]) in Tokamaks.As explained in Chapter 2, this radiation conveys information about the plasma density, temperature, magnetic equilibrium and impurity content. However, the measured data is spectrally and spatially-integrated and results from several physical phenomena affecting every ion species. Tore Supra's SXR diagnostics is based on semiconductor diodes presented in Chapter 3, along with a new gas detector successfully tested in laboratory and on Tore Supra. A new methodology for absolute spectral characterisation of photo detectors using a portable SXR tube is presented. Tomographic inversion algorithms, that grant access to reconstructions of the SXR emissivity field in a poloidal cross-section, are presented in Chapter 4. Improvements implemented on one particular algorithm are detailed with examples of application. A comparison between the position of the SXR emissivity maximum and the magnetic axis reconstructed by an equilibrium code is presented in Chapter 5.Chapter 6 presents an approach used to derive an impurity density from its SXR emissivity using the robustness of its SXR cooling factor with respect to impurity transport. The physics accounting for this robustness is studied and a first map of the domain of validity of this method is provided. Chapter 7 addresses poloidal asymmetries of the SXR emissivity field. Two types of asymmetries are presented as well as experiments conducted on ASDEX-U to verify their parametric dependences. A new type of SXR asymmetry, observed on Tore Supra is introduced.

EDELWEISS est une expérience de détection directe de matière noire froide non-baryonique sous forme de particules massives et faiblement interagissantes (connues sous l'acronyme de WIMPs), qui constituent actuellement les candidats les plus populaires pour rendre compte de la masse manquante de l'Univers. Dans ce but, EDELWEISS utilise des bolomètres de germanium opérés à température cryogénique (20 mK environ) dans le Laboratoire Souterrain de Modane (LSM) à la frontière franco-italienne. En particulier, depuis 2008, un nouveau type de détecteur est en fonctionnement, équipé d'électrodes concentriques pour optimiser le rejet des évènements de surface (détecteurs à grilles coplanaires). Cette thèse se décompose en plusieurs axes de recherche. Tout d'abord, nous avons réalisé des mesures concernant la collecte des charges dans les cristaux. Les lois de vitesse des porteurs (électrons et trous) ont été déterminées dans le germanium à 20 mK dans la direction <100>, et une étude complète de la répartition des charges a été menée, avec une évaluation de l'anisotropie du transport et de la diffusion transverse des porteurs. Ces résultats permettent d'avoir une meilleure compréhension du fonctionnement interne des détecteurs d'Edelweiss. Ensuite, des études portant sur l'amélioration des performances ont été effectuées. Nous avons en particulier permis d'optimiser la procédure de régénération des cristaux et améliorer le rejet passif des évènements de surface (β). Le volume utile de détection des détecteurs a été évalué en utilisant les raies de deux radio-isotopes activés cosmiquement, le 68Ge et le 65Zn. Enfin, une étude exhaustive portant sur l'étude des spectres à basse énergie a été menée, ce qui permet de mettre au point une méthode d'analyse systématique pour la recherche de WIMPs de basse masse dans EDELWEISS. / EDELWEISS is a direct non-baryonic cold dark matter detection experiment in the form of weakly interacting massive particles (also known as WIMPs), which currently constitute the most popular candidates to account for the missing mass in the Universe. To this purpose, EDELWEISS uses germanium bolometers at cryogenic temperature (20 mK approximately) in the Underground Laboratory of Modane (LSM) at the French-Italian border. Since 2008, a new type of detector is operated, equipped with concentric electrodes to optimize the rejection of surface events (coplanar-grid detectors). This thesis work is divided into several research orientations. First, we carried out measurements concerning charge collection in the crystals. The velocity laws of the carriers (electrons and holes) have been determined in germanium at 20 mK in the <100> orientation, and a complete study of charge sharing has been done, including an evaluation of the transport anisotropy and of the straggling of the carriers. These results lead to a better understanding of the inner properties of the EDELWEISS detectors. Then, studies relating to the improvement of the performances were carried out. In particular, we have optimized the space-charge cancellation procedure in the crystals and improved the passive rejection of surface events (β). The fiducial volume of the detectors has been evaluated using two X-ray lines from cosmically activated radionuclides: 68Ge and 65Zn. Lastly, an exhaustive study of the low energy spectra has been carried out, which makes it possible to develop a systematic analysis method for the search of low-mass WIMPs in EDELWEISS.

In this work, multi-band (multi-color) detector structures considering different semiconductor device concepts and architectures are presented. Results on detectors operating in ultraviolet-to-infrared regions (UV-to-IR) are discussed. Multi-band detectors are based on quantum dot (QD) structures; which include quantum-dots-in-a-well (DWELL), tunneling quantum dot infrared photodetectors (T-QDIPs), and bi-layer quantum dot infrared photodetectors (Bi-QDIPs); and homo-/heterojunction interfacial workfunction internal photoemission (HIWIP/HEIWIP) structures. QD-based detectors show multi-color characteristics in mid- and far-infrared (MIR/FIR) regions, where as HIWIP/HEIWIP detectors show responses in UV or near-infrared (NIR) regions, and MIR-to-FIR regions. In DWELL structures, InAs QDs are placed in an InGaAs/GaAs quantum well (QW) to introduce photon induced electronic transitions from energy states in the QD to that in QW, leading to multi-color response peaks. One of the DWELL detectors shows response peaks at ∼ 6.25, ∼ 10.5 and ∼ 23.3 µm. In T-QDIP structures, photoexcited carriers are selectively collected from InGaAs QDs through resonant tunneling, while the dark current is blocked using AlGaAs/InGaAsAlGaAs/ blocking barriers placed in the structure. A two-color T-QDIP with photoresponse peaks at 6 and 17 µm operating at room temperature and a 6 THz detector operating at 150 K are presented. Bi-QDIPs consist of two layers of InAs QDs with different QD sizes. The detector exhibits three distinct peaks at 5.6, 8.0, and 23.0 µm. A typical HIWIP/HEIWIP detector structure consists of a single (or series of) doped emitter(s) and undoped barrier(s), which are placed between two highly doped contact layers. The dual-band response arises from interband transitions of carriers in the undoped barrier and intraband transitions in the doped emitter. Two HIWIP detectors, p-GaAs/GaAs and p-Si/Si, showing interband responses with wavelength thresholds at 0.82 and 1.05 µm, and intraband responses with zero response thresholds at 70 and 32 µm, respectively, are presented. HEIWIP detectors based on n-GaN/AlGaN show an interband response in the UV region and intraband response in the 2-14 µm region. A GaN/AlGaN detector structure consisting of three electrical contacts for separate UV and IR active regions is proposed for simultaneous measurements of the two components of the photocurrent generated by UV and IR radiation.

"The Response of African Religion to Poverty with specific reference to the Umzimkhulu Municipality" is a particular effort of the wider world that researches the ways and means for combating the scourge of poverty in society aiming at securing a better future for the future generations. In as much as African traditional religion is part of the culture, tradition and custom of its tenants, and as such aims at the wellbeing of its tenants, it is able to offer a response to poverty. It teaches about the importance of the values of community, meaningful and life-affirming relationships and the value of ubuntu. All these clamour for extended sharing and extended participation which are essential if society will continue to exist. African traditional religion maintains an ethic that says: `Real poverty results from the blockage of the vital links'. Celebrating economic achievements in food must be preceded by the celebration of people. `Batho pele': is the contemporary Democratic South Africa's slogan that suggests putting people in the center of life. It does not only call us to serve the poor, but also to allow them to champion the courses of the kind of service they desire. African traditional religion teaches that, together with the other institutions that govern the lives of people, religion and politics should have among other things a concern about production and distribution of the resources, hence the claim: `Food is also politics'. In their dealing with the problem of poverty, religion, politics and other social institutions ought to dedicate a special place to instilling positive attitudes towards the concept of work among their tenants. In this way the slogan `Batho pele' or people first, does not merely mean waiting to be served, but it also means that every body to the best of their ability ought to be doing something towards the production of the items of service. The inclusiveness of African religion in terms of what it calls `community' cautions society about the importance of the other beings in its consideration of poverty alleviation. Our economic wellbeing depends mostly on our attitude towards the other non-personal neighbours, prominent among which is our common abode, the earth, the land. / Religious Studies and Arabic / D.Th. (Religious Studies)

The ability of physics to provide an understanding of our Universe lies in the essential interrelation between experiment and theory. But physics does not provide us only reliable representations of the causes acting in nature. Its powerful experimental devices and theoretical methods are the underlying reason of the explosive technological development of our time. LiNbO3 and LiTaO3 represent only one example of the essential impact of both experimental and theoretical investigations on their technological applications. Particularly, LiNbO3 has been the subject of many experimental studies due to its applications in electro-optic and integrated optical devices. Also, the doped LiNbO3 with rare-earth and transition metals could be used, for instance, as a material for tunable lasers. The previous theoretical studies devoted to LiNbO3 and LiTaO3 focused on their electronic structure, being an attempt to understand the microscopic origin of the paraelectric-to-ferroelectric phase transition of these materials. The ab initio lattice dynamics investigations performed so far were mainly aimed to identify the role of the individual atoms vibrations in the energetic of the phase transition. The lack of a reliable model for the zone-center lattice dynamics in these compounds motivated us to investigate this issue by means of ab initio frozen-phonon calculations. On the background of the obtained phonon frequencies and eigenvectors, we unambiguously identified all zone-center modes for LiNbO3 and the A1 ones for LiTaO3. Due to the above mentioned enlargement of the technological applications of LiNbO3 by doping with various ions, we focused on the analysis of the ground-state properties of this material when doped with Fe and Cr. Even if the theoretical approach used in our calculations is not predictive with respect to the optical properties of the physical systems in study, a certain insight on this problem could be gained from the analysis of the effect of the atomic positions relaxation on the impurities energy levels localized in the optical band gap.

I present and discuss the results of calculations ofelectronic structures of perfect and defective CaF2 and BaF2 crystals. These are based on the ab initio Hartree-Fock method with electron correlation corrections and ondensity-functional theory calculations with different exchange-correlation functionals, including hybrid exchange techniques.The defective systems include F centers, M centers, O-V dipoles, Hydrogen impurities and H centers.

The discovery of topological quantum states of matter has required physicists to look beyond Landau’s theory of symmetry-breaking, previously the main paradigm for<br>studying states of matter. This has led also to the development of new topological theories for describing the novel properties. In this dissertation an investigation in this<br>frontier research area is presented, which looks at the interplay between the quantum geometry of these states, defects and disorder. After a brief introduction to the topological quantum states of matter considered herein, some aspects of my work in this area are described. First, the disorder-induced band structure engineering of topological insulator surface states is considered, which is possible due to their resilience from Anderson localization, and believed to be a consequence of their topological origin.<br>Next, the idiosyncratic behavior of these same surface states is considered, as observed in experiments on thin film topological insulators, in response to competition between<br>hybridization effects and an in-plane magnetic field. Then moving in a very different direction, the uncovering of topological ‘gravitational’ response is explained: the<br>topologically-protected charge response of two dimensional gapped electronic topological states to a special kind of 0-dimensional boundary – a disclination – that encodes spatial curvature. Finally, an intriguing relation between the gravitational response of quantum Hall states, and their response to an apparently unrelated perturbation – nonuniform electric fields is reported. <br>