Self-Assembly of Polyion–Surfactant Ion Complex Salts in Mixtures with Water and n-Alcohols

Phase behavior and structural features were investigated for "complex salts", consisting of the cationic hexadecyltrimethylammonium (CTA) surfactant with polyacrylate (PA(n), n = 30 or 6000) counterions, mixed with water and different n-alcohols (ethanol, butanol, hexanol, octanol, and decanol). The liquid crystalline structures formed were identified by small-angle X-ray scattering measurements, which provided information about the changes in the geometry of the aggregates as functions of the concentration and chain length of the added n-alcohol. The obtained results were compared with a previous work on similar ternary mixtures of the same cationic surfactant but with the monomeric bromide counterion, CTABr (Fontell, K; Khan, A.; Lindstrom, B.; Maciejewska, D.; Puang-Ngem, S. Colloid Polym. Sc., 1991, 269, 727). In general, the same phases were detected in systems with the complex salts CTAPA(n) as in systems with CTABr, but the swelling of the various liquid crystalline phases by water was much more limited in the complex salt systems. An isotropic alcoholic phase was observed with all alcohols and the size of this region of the phase diagram increased for the shorter alcohols, except for ethanol. For mixtures with octanol and ethanol, in particular, the extensions of the disordered isotropic phases were larger for the complex salt with the shorter polyacrylate ions

Économie politique des rapports de genre dans les technologies de l'information et de la communication du développement agricole. Le cas des plateformes de connaissances accessibles en ligne destinée aux agriculteurs au Kenya

Low-income sub-Saharan African countries are confronted with demographic explosion since the last 60 years. Consequently, agriculture plays a key role in ensuring food security. The agricultural sector is also the main source of employment in this region. Women are the major contributing labour force in agriculture in these sub-Saharan African countries. Connected to their key role in the agricultural sector, women farmers are prioritised in policy intervention. Moreover, agricultural extension services are necessary to adapt to different constraints in these countries. Transfer of knowledge is also required to guarantee farm yields and consequently improve small-scale farmers’ livelihoods. Lately, information and communication technologies (ICTs) have enabled the development of new tools, aimed at improving the scope and the effectiveness of advisory services. Policy makers in sub-Saharan African countries are nonetheless confronted with critical questions regarding the impact of these tools, which can also contribute to a ‘digital gender gap’. These issues particularly concern women farmers.This PhD research analyses how ICT tools take into account gender relations, and the situation of women farmers. The thesis is based on the case of Kenya. The dissertation particularly focuses on the development of knowledge-based platforms in agriculture, an ICT policy instrument used by the Kenyan Government to achieve public policy objectives. This country is emblematic because it believes in the assumption that platforms can be inclusive of women farmers’. To answer to this research question, the work is based on three different institutional economic research approaches: feminist economics, the French regulation theory, and economics of services. A conceptual and methodological framework is presented to analyse the inclusion of gender equality in knowledge-based platforms at macro-, meso-, and micro- level.The results provide evidence that gender equality objectives is a fundamental guiding principle to the Government of Kenya. The analysis show that platforms are considered as new tools of inclusiveness in farm advisory services innovation. Observations from a developed platform typology framework show however that platforms can be source of gender inequality. It especially concerns women farmers unequal access to these instruments and the standardised services that they offer. This is essentially related to the institutional nature of the platform. Indeed, as it turns out, a high number of these instruments are based upon complex partnerships, and financed by multi-national corporations and/or foundations from the agrifood industry based in the Northern hemisphere. Combining institutional economic approaches allowed to bring out critical points of inclusion to be considered by policy makers and platform developers. Disregarding these specificities may make these platforms into new vectors of exclusion. Recognising and taking into account the conditions for inclusion can bring to light powerful levers for improving the efficiency of platforms.Face à l’explosion démographique des pays à faible revenu en Afrique sub-saharienne, l’agriculture joue un rôle primordial pour garantir la sécurité alimentaire. Le secteur agricole est de plus la principale source d'emploi dans cette région. Les femmes constituent la principale main-d'œuvre agricole de ces pays. En raison de leur rôle clé dans le secteur agricole, les agricultrices sont prioritaires dans les interventions politiques. Par ailleurs, dans ces pays, le conseil agricole et le partage des connaissances sont nécessaires pour s’adapter à de nouvelles contraintes. Depuis quelques années, les technologies de l’information et de la communication (TIC) ont permis le développement de nouveaux outils visant à améliorer la portée et l’efficacité du conseil. Les gouvernements de ces pays sont cependant confrontés à des critiques concernant l'impact de ces outils, qui peuvent également contribuer à une fracture numérique touchant plus particulièrement les femmes qui travaillent dans les exploitations agricoles familiales.La thèse de doctorat analyse comment les outils TIC tiennent compte des rapports de genre, et de la situation des femmes qui travaillent sur l’exploitation agricole familiale. La thèse est fondée sur le cas du Kenya. Elle est focalisée sur le développement des plateformes de connaissances, un instrument TIC utilisé par le Gouvernement kenyan pour atteindre les objectifs de politiques publiques. Ce pays est emblématique car il fait l'hypothèse que les plateformes peuvent être inclusives des agricultrices.Pour cette recherche, le travail s'appuie sur trois approches d’économie institutionnelle : l’économie féministe, la théorie de la régulation, et l'économie des services. Il présente un cadre méthodologique et conceptuel, développé pour analyser l'intégration des rapports de genre dans les plateformes aux échelles macro, méso et micro.Les résultats montrent que les rapports de genre sont présentés associés à un objectif d'équité pour le Gouvernement Kenyan. L'analyse confirme que les plateformes sont considérées comme de nouveaux outils d'inclusion du système de vulgarisation du gouvernement. La typologie de plateformes développée dans ce travail montre cependant que ces instruments peuvent être une source d'inégalité. Il s'agit en particulier de l'inégalité d'accès pour les agricultrices et de services standardisés qui ne correspondent pas aux attentes de ces femmes. La conjugaison de différentes approches économiques institutionnelles a permis d'analyser comment les évolutions institutionnelles affectent l'inclusion des objectifs d’égalité des sexes dans l’intervention publique et dans le fonctionnement effectif des plateformes. Les résultats présentent des leviers d’action pouvant être pris en considération par les politiques et les concepteurs des plateformes, pour une tenir compte des rapports de genre dans ce système de vulgarisation agricole et éviter d’engendrer de nouvelles discrimination. L'analyse révèle l'importance de disposer d'un espace d'intervention publique et de coordination dans ce nouveau système de conseil agricole basé sur les TICs

Tungsten Carbide Nanotubes Supported Platinum Nanoparticles as a Potential Sensing Platform for Oxalic Acid

Supported tungsten carbide is an efficient and vital nanomaterial for the development of high-performance, sensitive, and selective electrochemical sensors. In this work, tungsten carbide with tube-like nanostructures (WC NTs) supported platinum nanoparticles (PtNPs) are synthesized and explored as an efficient catalyst toward electrochemical oxidation of oxalic acid for the first the time. The WC NTs supported PtNPs modified glassy carbon (GC) electrode is highly sensitive toward the electrochemical oxidation of oxalic acid. A large decrease in the oxidation overpotential (220 mV) and significant enhancement in the peak current compared to unmodified and Pt/C modified GC electrodes have been observed without using any redox mediator. Moreover, WC NTs supported PtNPs modified electrode possessed wide linear concentration ranges from 0 to 125 nM and a higher sensitivity toward the oxidation of oxalic acid (80 nA/nM) achieved by the amperometry method. The present modified electrode showed an experimentally determined lowest detection limit (LOD) of 12 nM (S/N = 3). Further, WC NTs supported PtNPs electrode can be demonstrated to have an excellent selectivity toward the detection of oxalic acid in the presence of a 200-fold excess of major important interferents. The practical application of WC NTs supported PtNPs has also been demonstrated in the detection of oxalic acid in tomato fruit sample, by differential pulse voltammetry under optimized conditions

Development of a Saccharomyces cerevisiae Strain with Enhanced Resistance to Phenolic Fermentation Inhibitors in Lignocellulose Hydrolysates by Heterologous Expression of Laccase

To improve production of fuel ethanol from renewable raw materials, laccase from the white rot fungus Trametes versicolor was expressed under control of the PGK1 promoter in Saccharomyces cerevisiae to increase its resistance to phenolic inhibitors in lignocellulose hydrolysates. It was found that the laccase activity could be enhanced twofold by simultaneous overexpression of the homologous t-SNARE Sso2p. The factors affecting the level of active laccase obtained, besides the cultivation temperature, included pH and aeration. Laccase-expressing and Sso2p-overexpressing S. cerevisiae was cultivated in the presence of coniferyl aldehyde to examine resistance to lignocellulose-derived phenolic fermentation inhibitors. The laccase-producing transformant had the ability to convert coniferyl aldehyde at a faster rate than a control transformant not expressing laccase, which enabled faster growth and ethanol formation. The laccase-producing transformant was also able to ferment a dilute acid spruce hydrolysate at a faster rate than the control transformant. A decrease in the content of low-molecular-mass aromatic compounds, accompanied by an increase in the content of high-molecular-mass compounds, was observed during fermentation with the laccase-expressing strain, illustrating that laccase was active even at the very low levels of oxygen supplied. Our results demonstrate the importance of phenolic compounds as fermentation inhibitors and the advantage of using laccase-expressing yeast strains for producing ethanol from lignocellulose