No / Mechanistic understanding of competitive destabilization of carbamazepine:nicotinamide and carbamazepine:saccharin cocrystals under solvent free conditions has been investigated. The crystal phase transformations were monitored using hot stage microscopy, variable-temperature powder X-ray diffraction, and sublimation experiments. The destabilization of the two cocrystals occurs via two distinct mechanisms: vapor and eutectic phase formations. Vapor pressure measurements and thermodynamic calculations using fusion and sublimation enthalpies were in good agreement with experimental findings. The mechanistic understanding is important to maintain the stability of cocrystals during solvent free green manufacturing. / EPSRC (EP/J003360/1, EP/ L027011/1). MHD. Bashir would like to thank CARA for providing doctoral degree scholarship.

Yes / The main objective of this research is to investigate solid-state destabilization mechanism and kinetics of the model cocrystal caffeine : malonic acid (CA:MO) in presence of oxalic acid (OX) as a structural competitor. Competitive destabilization of CA:MO and subsequent formation of CA:OX takes place at temperatures significantly below its melting point. Destabilization mechanism was found to be mediated by sublimation of both CA:MO and OX. During CA:MO destabilization, free CA could not be detected and direct transformation to CA:OX cocrystal was observed. The destabilization kinetics follow Prout-Tompkins nucleation and crystal growth model with activation energy of 133.91 kJ/mol and subsequent CA:OX growth kinetic follow Ginstling – Brounshtien diffusion model with activation energy of kJ/mol.

The research was an investigation into the phenomenon of external military interventions in Africa. The broad interpretation often given to intervention compelled both an African view on the subject and an operational definition. External military intervention was defined as the execution of any military plans by a state or its citizens in another state, in a manner that radically alters the existing socio-political, economic and military conditions in the target state, with or without its consent. The role and effects of external powers in six conflict cases in Africa were examined. A taxonomy on intervention identified the phenomenon in its internal and external manifestations. Apart from the more publicised military role of extra-African powers in the region, the increasing role of African States as intra-continental interventionists was also considered. The research concluded that aspects of the problems perceived as endemically African may have their roots in events influenced by external actions. However, some African states were seen as contributing to this situation as well. The view was expressed that restraints by states in their exercise of power and perceived wisdom may reduce the level of conflicts in the contemporary world. / British Foreign and Commonwealth Office, British Council

The physicochemical properties of pyrolysis oil have been shown to be dependent on feedstock composition. Accelerated aging tests were performed to understand the effects of feedstock, condensate fraction collected, and filtration on the stability of pyrolysis oil. In this study, pyrolysis oil properties critical for downstream upgrading were measured and compared for different feedstock weight ratios of pine clearwood and pine bark. Post-condensation filtration of pyrolysis oil was evaluated using both lab-scale and pilot plant-scale centrifugal filtration with several operational parameters evaluated. The pilot-plant centrifuge can be used as a three-phase separator [light liquid-heavy liquid-solids] or a two-phase clarifier [liquid-solid]. Since pyrolysis oil is an oil-water micro-emulsion, separation of the heavy and light liquid phases is difficult; therefore, emulsion destabilization studies were performed in concert with centrifugation. Physicochemical properties were monitored to determine the impact of the production and processing parameters on the oil properties critical to biofuel applications.

Ce travail porte sur les processus locaux de déstabilisation, d'érosion et de transport des sédiments sous l'action des vagues en zone de déferlement. L'étude s'appuie sur une modélisation physique menée dans le canal à houle du LEGI avec un sédiment léger pour respecter les similitudes de Rouse et de Shields. Dans ces expériences, nous développons des techniques de mesure optiques, acoustiques et de pression. Ces capteurs nous permettent de caractériser la couche limite en vitesses et en concentration mais aussi d'étudier la réponse du lit aux sollicitations des vagues via la quantification de profondeurs d'érosion, d'épaisseurs de la couche de sédiments en mouvement, fortement concentrée et de la transmission de la pression interstitielle. L'influence des non-linéarités de la houle sur le transport sédimentaire est étudiée, en particulier la dissymétrie de l'accélération (ou asymétrie). Elle est constatée sur la mesure de flux sédimentaire. Deux mécanismes sont identifiés. i) Une asymétrie hors de la couche limite conduit à une dissymétrie de vitesse dans la couche limite qui produit un transport net. ii) L'accélération hors de la couche limite est proportionnelle au gradient horizontal de pression et l'effort de pression qu'il suscite peut déstabiliser le lit (plug-flow). Nous vérifions dans nos expériences que la contrainte de cisaillement (caractérisée par le nombre de Shields) et le gradient de pression (caractérisé par le nombre de Sleath) peuvent alternativement déstabiliser le lit. / This study investigates the local processes of surf-zone bed sediment destabilization, erosion and transport. It is based on a physical model in the LEGI wave flume using lightweight sediment to fulfill scaling laws. Optical, acoustical and pressure sensors measurements technics were developped. The sensors are used simultaneously to characterize the bottom boundary layer in terms of velocities and concentration. The bed response was also determined measuring erosion depth, sheet-flow thickness and pore-pressure pressure transmission. This work mainly focuses on non-linearities of the flow and their effect on transport, especially the acceleration skewness. It is shown that this asymmetry contributes to the sediment transport in two different ways. One mechanism is that the free-stream asymmetry of the flow results in a velocity skewness near the bed, it produces a net transport. The second one is that the free-stream acceleration is proportional to the horizontal pressure gradient. This pressure stress can destabilize the bed in a form of a plug-flow. Our results show that shear stress (characterized by the Shields number) and pressure gradients (characterized by the Sleath number) can in turn destabilize the bed.

Ce travail porte sur les processus locaux de déstabilisation, d'érosion et de transport des sédiments sous l'action des vagues en zone de déferlement. L'étude s'appuie sur une modélisation physique menée dans le canal à houle du LEGI avec un sédiment léger pour respecter les similitudes de Rouse et de Shields. Dans ces expériences, nous développons des techniques de mesure optiques, acoustiques et de pression. Ces capteurs nous permettent de caractériser la couche limite en vitesses et en concentration mais aussi d'étudier la réponse du lit aux sollicitations des vagues via la quantification de profondeurs d'érosion, d'épaisseurs de la couche de sédiments en mouvement, fortement concentrée et de la transmission de la pression interstitielle. L'influence des non-linéarités de la houle sur le transport sédimentaire est étudiée, en particulier la dissymétrie de l'accélération (ou asymétrie). Elle est constatée sur la mesure de flux sédimentaire. Deux mécanismes sont identifiés. i) Une asymétrie hors de la couche limite conduit à une dissymétrie de vitesse dans la couche limite qui produit un transport net. ii) L'accélération hors de la couche limite est proportionnelle au gradient horizontal de pression et l'effort de pression qu'il suscite peut déstabiliser le lit (plug-flow). Nous vérifions dans nos expériences que la contrainte de cisaillement (caractérisée par le nombre de Shields) et le gradient de pression (caractérisé par le nombre de Sleath) peuvent alternativement déstabiliser le lit.

La stabilité gravitaire des ouvrages hydrauliques (digues fluviales, barrage en remblai, ...) est un problème complexifié par la présence d'infiltration d'eau au sein même de l'ouvrage et de ses fondations. Le territoire national compte près de 10000 km de digues, d'où un enjeu important en terme de risque d'inondation. Les déstabilisations gravitaires observées sur les ouvrages hydrauliques se distinguent par leur brièveté et par leur faible emprise spatiale. L'objectif de ce travail de thèse est d'étudier spécifiquement ces instabilités brèves et de faible déplacement cumulé le long de la pente dans le cas de matériaux granulaires saturés. Dans un premier temps, une campagne expérimentale a été effectuée sur la base d'un protocole de chargement progressif dans lequel un échantillon de sol est lentement incliné jusqu'à obtenir une déstabilisation massive. Il en ressort une phénoménologie complexe composée d'un nombre de précurseurs d'avalanche dépendant de la fraction volumique de l'échantillon. Une forte influence de la fraction volumique du sol sur le seuil de stabilité est également mise en avant. Une deuxième campagne expérimentale basée sur un protocole d'effondrement contrôlé, à inclinaison imposée, a été menée dans le but d'amplifier la cinématique de déstabilisation observée en chargement progressif. Mis à part les échantillons les plus denses qui produisent de simples avalanches de surface, on observe dans les autres cas un ou plusieurs événements successifs, d'allure circulaire, mobilisant des profondeurs très importantes contrairement aux avalanches de surface.. Outre l'inclinaison, on voit bien que, là encore, la fraction volumique est un paramètre clé dans le contrôle de la cinématique de déstabilisation. Des essais préliminaires laissent cependant entendre que, au-delà de la fraction volumique, c'est la microstructure qui semble être le vrai paramètre de contrôle à travers notamment la forme des grains et leur enchevêtrement. / Gravitational stability of hydraulic structures (river dykes, embankment dam,...) is a problem complicated by the presence of water infiltration within the structure and its foundations. Our country has about 10,000 km of dikes and gravitational failure is a major challenge in terms of flood risk. In hydraulic structures, these destabilizations are characterized by their brevity and their small spatial extent. The objective of this thesis is to study specifically this type of brief instabilities in the case of a saturated granular material. A first series of experiments was carried out on the basis of a progressive loading protocol in which a soil sample is tilted slowly until a massive destabilization is triggered. It shows a phenomenology complex consisting of a number of precursory events prior final avalanching, dependent on the solid volume fraction of the sample. A strong impact of the solid volume fraction of the soil on the stability threshold is also highlighted. A second series of experiments based on a protocol of collapse controlled at imposed slope was conducted to amplify the kinematics of destabilization observed by progressive loading. Apart from the denser samples that produce simple surface avalanches, one or more successive events are observed in other cases. Unlike surface avalanches, these events mobilize grains much deeper, in an almost semi-circular area. In addition to slope angle, solid volume fraction is once again a key parameter in controlling the kinematics of destabilization. Preliminary tests suggest, however, that, beyond solid volume fraction, microstructure appears to be the true control parameter, particularly through grain shape and texture.

Ce travail de thèse a porté sur l’étude de littoraux sous l’influence de deux grands deltas, l’Amazone et le Mékong, avec un focus sur les plages et cheniers de Guyane intégrant le système de dispersion vaseuse de l’Amazone, et sur les liens entre la déstabilisation du littoral du delta du Mékong et les changements morpho-bathymétriques des chenaux deltaïques sous influence anthropique croissante. L’étude de la plage de Montjoly en Guyane a été conduite en combinant une approche innovante de photogrammétrie aéroportée SfM (Structure from Motion), des mesures hydrodynamiques, bathymétriques, et la modélisation de la propagation des houles à travers cette bathymétrie. Les résultats obtenus montrent le potentiel considérable de la technique de photogrammétrie SfM pour l’étude géomorphologique des plages, et confirment un modèle de rotation de la plage sous l'influence de banc de vase. Le suivi du second site d’étude, un chenier en recul sur un ancien polder rizicole vaseux, au travers d'une analyse multi décennale d’images satellites et des mesures de terrain, a démontré très finement les taux (atteignant 160 m par an) et mécanismes de recul du substrat vaseux en lien avec sa rhéologie.L’analyse de l'évolution de la bathymétrie des chenaux deltaïques du Mékong sur une décennie (1998 et 2008), conduite à travers une méthode sous SIG, a permis de quantifier une perte nette de 200 millions de m3 de sédiments et un approfondissement de chenaux ne relevant pas de processus naturels mais d'extraction de granulats.Ces prélèvements importants de sédiments ont des répercussions importantes sur les apports de sédiments au littoral du delta qui montre des taux d’érosion importants. / This thesis is a geomorphic study of two separate sites associated with two large deltas: the Amazon and the Mekong, with a focus on a beach and chenier in French Guiana integrated into the mud dispersal system of the Amazon, and on the links between destabilization of the Mekong delta shoreline and morpho-bathymetric changes in the deltaic channels under increasing human influence.The study of Montjoly beach in French Guiana was carried out using a combination of an innovative approach in SfM (Structure from Motion) airborne photogrammetry, hydrodynamic and bathymetric measurements, and wave propagation modelling over the nearshore bathymetry. The results show the strong potential of SfM photogrammetry in high-resolution morphometric and sediment budget surveys of sandy beach, and confirm a previously proposed model of beach rotation under mud-bank influence.The second field site in French Guiana, a retreating chenier over a muddy abandoned polder formerly a rice fields, work based on a multi-decadal analysis of satellite images combined with short-term field topographic and hydrodynamic measurements highlighted high rates of chenier migration (up to 160 m a year) and retreat mechanisms over the muddy substrate due to its rheology.A GIS-based analysis of bathymetric changes in the deltaic channels of the Mekong over a 10-year period (1998 to 2008) enabled the quantification of a net loss of 200 million m3 of sediments and an increase in the mean depth of the channels, which appears as unnatural and due to sand mining.These important sediment extractions have serious repercussions on sediment supply to the Mekong delta coast, which shows important rates of erosion.

The rise of the 21st Century Islamic extremist movement, which was mobilised by the al-Qaeda attacks of and responses to September 11, 2001, heralds a new period in the history of terrorism. The increased frequency and intensity of this type of terrorism affects every nation in the world, not least Australia. Rising to meet the challenges posed by terrorism is the field of terrorism studies, the field which aims at understanding, explaining, and countering terrorism. Despite the importance of the field, it has been beleaguered with criticisms since its inception as a response to the rise of international terrorism. These criticisms specifically aim at the field's lack of objectivity, abstraction, levels of research, and levels of analysis. These criticisms were the impetus behind the adoption of the methodology of this thesis, which offers the distinct ability to understand, explain, and forecast the way in which terrorists interact within covert cells. Through social network analysis, this thesis examines four terrorist cells that have operated in or against Australia. These cells are from the groups Hrvatsko Revolucionarno Bratstvo (Croatian Revolutionary Brotherhood), Aum Shinrikyo (Supreme Truth), Lashkar-e-Taiba (Army of the Pure), and Jemaah Islamiyah (Islamic Community) and operated between 1963 and 2003. Essentially, this methodology attempts to discover, map, and analyse the interaction within the cells during the covert stage of their respective operations. Following this, the results are analysed through the traditional social network analysis frameworks to discover the internal dynamics of the cell and identify the critical nodes (leaders) within the cells. Destabilisation techniques are subsequently employed, targeting these critical nodes to establish the most effective disruption techniques from a counter-terrorism point of view. The major findings of this thesis are: (1) that cells with a focus on efficiency rather than covertness were more successful in completing their objectives (contrary to popular belief); and (2) betweenness centrality (control over the flow of communication) is a critical factor in identifying leaders within terrorist cells. The analysis also offered significant insight into how a Jemaah Islamiyah cell might operate effectively in Australia, as well as the importance of local contacts to terrorist operations and the significance of international counter-terrorism cooperation and coordination.