Gabon is a Sub-Saharan francophone country which has been independent since August 1960. Its Educational System is modelled on the French System. However, the Gabonese Education System currently does not have any guidelines or policies for the system-wide implementation, integration and use of Information and Communication Technology (ICT) into the education system. The Gabonese Government committed itself to some ICT-related partnerships, but did not launch any programme or activity relating to those commitments. In addition, the Government provided funding to change the country’s Internet connectivity by satellite with the WASC/SAT3 sub-marine cable in order to make Internet access and connection ten times cheaper at the international level. Unfortunately, the benefit from this investment is not experienced in the country as the potential users, such as teachers, keep having challenges with Internet connection. After fifty years of independence, the government also does not offer sufficient opportunity for teachers to enhance their pedagogical knowledge and skill through teacher professional development (TPD). As a result, no research, guidelines or policies exist for the implementation and use of Open Distance Learning (ODL) for TPD supported by ICT. The aim of this qualitative descriptive exploratory research study was to explore, describe and understand the enablers and challenges of initiating ICT in the ODL training of Gabonese in-service teachers. Although the academic seat for this research was the School of Continuing Teacher Education on the Potchefstroom Campus of the North-West University in South Africa, the research project’s focus, conceptualisation, data-collection and data-interpretation were all based and conducted within the researcher’s heimat, i.e. the Gabonese Education System context. An interactive qualitative casestudy research design (Denzin & Lincoln, 2005; Merriam, 1998) was used in this investigation to obtain in-depth context sensitive data concerning the attitudes, fears, needs, expectations, infrastructure and readiness of the Gabonese Education teachers (at schools and training institutions) for the implementation and use of ICT for ODL training of Gabonese English (second language) teachers, collected through qualitative research methods, i.e. semi-structured open-ended individual and focusgroup interviews, as well as additional research artefacts in the form of photographs to visually record the unique contexts involved. The researcher decided to involve Gabonese English (second language) teachers in the investigation, as he has worked in this discipline for at least twenty years. To ensure sufficient participants, the researcher made use of a snowball strategy where participants in the research referred others. Participants were also selected according to specific selection criteria. Two English (second language) teachers, one school principal, four ICT specialists, one advisor of English teachers, and one inspector of English teachers (ICT specialist) participated in eight individual interviews. Nine English teachers and two advisors of English teachers participated in four focus-group interviews. All interviews were conducted in French. At the North-West University in South Africa, the researcher transcribed the interview data and used ATLAS.ti™ (qualitative data-analysis software) to construct an integrated data-set for analysis. Qualitative data-analysis was performed under the guidance of an expert researcher in qualitative data-analysis. The relevant research findings were translated into English for the purpose of this report. Qualitative data-analysis of the integrated data-set identified six categories of data related to three themes, i.e. (i) Gabonese Education, (ii) ICT in Gabon and (iii) ODL in Gabon. The six categories are: (i) Challenges of Gabonese Education, (ii) Enablers of Gabonese Education, (iii) Challenges to implementation and integration of ICT, (iv) Enablers of ICT; (v) Challenges of ODL, and (vi) Enablers of ODL. These categories supported by codes and quotations provide basic ideas on the research enablers and challenges of initiating ICT in ODL training of Gabonese in-service teachers. The discussion comprises thirty codes, and recommendations are made. The findings of this rich qualitative exploration could benefit and support the Gabonese Education Department, policy makers and academic institutions in their quest to implement, integrate and use ICT in the TPD of in-service teachers via DE and ODL. / Thesis (MEd (Curriculum Development))--North-West University, Potchefstroom Campus, 2013.

Gabon is a Sub-Saharan francophone country which has been independent since August 1960. Its Educational System is modelled on the French System. However, the Gabonese Education System currently does not have any guidelines or policies for the system-wide implementation, integration and use of Information and Communication Technology (ICT) into the education system. The Gabonese Government committed itself to some ICT-related partnerships, but did not launch any programme or activity relating to those commitments. In addition, the Government provided funding to change the country’s Internet connectivity by satellite with the WASC/SAT3 sub-marine cable in order to make Internet access and connection ten times cheaper at the international level. Unfortunately, the benefit from this investment is not experienced in the country as the potential users, such as teachers, keep having challenges with Internet connection. After fifty years of independence, the government also does not offer sufficient opportunity for teachers to enhance their pedagogical knowledge and skill through teacher professional development (TPD). As a result, no research, guidelines or policies exist for the implementation and use of Open Distance Learning (ODL) for TPD supported by ICT. The aim of this qualitative descriptive exploratory research study was to explore, describe and understand the enablers and challenges of initiating ICT in the ODL training of Gabonese in-service teachers. Although the academic seat for this research was the School of Continuing Teacher Education on the Potchefstroom Campus of the North-West University in South Africa, the research project’s focus, conceptualisation, data-collection and data-interpretation were all based and conducted within the researcher’s heimat, i.e. the Gabonese Education System context. An interactive qualitative casestudy research design (Denzin & Lincoln, 2005; Merriam, 1998) was used in this investigation to obtain in-depth context sensitive data concerning the attitudes, fears, needs, expectations, infrastructure and readiness of the Gabonese Education teachers (at schools and training institutions) for the implementation and use of ICT for ODL training of Gabonese English (second language) teachers, collected through qualitative research methods, i.e. semi-structured open-ended individual and focusgroup interviews, as well as additional research artefacts in the form of photographs to visually record the unique contexts involved. The researcher decided to involve Gabonese English (second language) teachers in the investigation, as he has worked in this discipline for at least twenty years. To ensure sufficient participants, the researcher made use of a snowball strategy where participants in the research referred others. Participants were also selected according to specific selection criteria. Two English (second language) teachers, one school principal, four ICT specialists, one advisor of English teachers, and one inspector of English teachers (ICT specialist) participated in eight individual interviews. Nine English teachers and two advisors of English teachers participated in four focus-group interviews. All interviews were conducted in French. At the North-West University in South Africa, the researcher transcribed the interview data and used ATLAS.ti™ (qualitative data-analysis software) to construct an integrated data-set for analysis. Qualitative data-analysis was performed under the guidance of an expert researcher in qualitative data-analysis. The relevant research findings were translated into English for the purpose of this report. Qualitative data-analysis of the integrated data-set identified six categories of data related to three themes, i.e. (i) Gabonese Education, (ii) ICT in Gabon and (iii) ODL in Gabon. The six categories are: (i) Challenges of Gabonese Education, (ii) Enablers of Gabonese Education, (iii) Challenges to implementation and integration of ICT, (iv) Enablers of ICT; (v) Challenges of ODL, and (vi) Enablers of ODL. These categories supported by codes and quotations provide basic ideas on the research enablers and challenges of initiating ICT in ODL training of Gabonese in-service teachers. The discussion comprises thirty codes, and recommendations are made. The findings of this rich qualitative exploration could benefit and support the Gabonese Education Department, policy makers and academic institutions in their quest to implement, integrate and use ICT in the TPD of in-service teachers via DE and ODL. / Thesis (MEd (Curriculum Development))--North-West University, Potchefstroom Campus, 2013.

The effective and sustainable use of ICTs (Information and Communication Technologies) in education has become commonplace as it is necessary to keep up with demands of the 21st century. ICT in education has become a tool for the empowerment of both teachers and learners for better teaching and learning. Although various ICT strategies and initiatives are implemented across South Africa, no system-wide effective and sustainable ICT integration in schools has yet come about. The pace of integration is slow and teachers avoid using ICT in their teaching and learning practices due to insufficient training. The aim of teacher professional development (TPD) is to improve teachers’ ICT application skills and knowledge, as well as to enable teachers to integrate ICT effectively in their classroom practices. Principals play a vital role in leading school reform, implementing innovations and bringing about change. The widespread assumption that high-quality leadership is an essential dimension of successful school management, leads to the question of how principals can influence teachers’ effective and sustainable integration of ICT into classrooms through TPD activities. Therefore, the purpose of this research was to determine the influence that principals have on teachers’ ICT integration through TPD. As school leadership is frequently cited as an essential for the successful integration of ICT into education, the very position of the principal is associated with authority, accountability and power. My initial research is based on Stoner’s (1999) Adapted Life Cycle Model of Learning Technology Integration. I used this model to illustrate the principals’ influence on teachers’ integration of ICT into education. From this review subsidiary questions emerged. Qualitative research through in-depth interviews formed the basis of an interpretative perspective, allowing principals to reflect on ICT integration, as well as their influence on teachers’ use of ICT. This study followed a basic grounded theory approach where I assumed an inductive stance and strived to derive meaning from the data in order to develop new theory. Pre-defined theoretical criteria determined the selection of the respondents to ensure validity of the data. The seven principals represented secondary schools across cultural and socio-economic levels. The perceptions and experiences of the principals were analysed, compared, and patterns of influence were identified. This study indicated that principals do not only influence the integration of ICT in classrooms through their leadership and management styles, but also through their attitude toward ICT integration, knowledge on related ICT and TPD issues, as well as their strategic thinking on ICT integration. Emerging findings on the role of the principal lead to new insights on the empowerment of teachers. The study resulted in a proposed theoretical framework that indicates the interrelatedness of the emerging patterns that influence the principals’ role through TPD. / Thesis (PhD)--University of Pretoria, 2009. / Curriculum Studies / unrestricted

L’usage des élastomères en tant que matériau ne peut se concevoir sans l’utilisation de certaines charges dites renforçantes. Bien qu’une variété plutôt large de minéraux en poudre puisse être associée aux élastomères, deux charges sont très majoritairement utilisées de par leur haute capacité renforçante, les noirs de carbone et les silices actives et hautement structurées. L’utilisation de la silice n’a été envisagée, à partir des années 1980, que grâce à un contrôle fin de sa chimie de surface, de ses silanols hydrophiles et de son traitement par silanes spécifiquement dessinés pour satisfaire une application précise. La preuve expérimentale quantifiant les interactions charge – polymère est grandement souhaitée. C’est précisément le premier but que cette thèse tente d’approcher. Pour tenter d’atteindre cet objectif, nous proposons d’étudier dans ce travail l’évaluation de l’adsorption d'un polymère, une série de HNBR, sur des charges, noir de carbone et silice traitée ou non par des silanes spécifiquement désignés, d’un point de vue énergétique et moléculaire au moyen de la microcalorimétrie à écoulement (FMC). L'application de cet outil, relativement connu dans le cadre des interactions petite molécule – charge est plutôt original dans l’étude des couples polymère – charge. Notre deuxième but est donc, et grâce à une connaissance fine de la chimie des surface d'une silice, de ses traitements par des silanes, et de l'adsorption du polymère sur sa surface, d'explorer la corrélation entre le traitement et les propriétés macroscopiques dans le but d'établir une relation de cause à effet. / Most actual uses of elastomers are not even conceivable without the assistance of reinforcing filler. In this field, "silane-technology" brought into evidence the necessity of monitoring the competition that routinely rises between two determinant factors: polymer-filler interactions and filler-filler interactions. As a result, an important database founded essentially on the characterization of the surfaces chemistry and surface energy of the two antagonist elements had to be gathered. However, the determination of the consequence of such characters on the factual polymer-filler interactions remains rudimentary, such as bound rubber gravimetric measurements. Experimental prove which is able to quantify such interactions is badly needed. This is, actually, the first objective that we tried to achieve. In order to do so, we propose in this work to study, from the energy point of view using flow micro calorimeter (FMC), the evolution of the adsorption of a series of HNBR on the surface of carbon black (CB) and silicas unmodified and modified by selected silanes. If the goal of the silane technology is to design coupling agents that are able to satisfy a specific application, especially those related to the energy dissipation, the mechanism through which such a process is achieved is not fully understood. Thus, and based on a fine knowledge of surface chemistry, surface treatments and polymer adsorption, our second objective is to explore the cause-to-effect links that ought to exist between filler surface treatments and blends macroscopic properties.

L'hydrocondensation des oxydes de carbone sur un catalyseur Fe/Al₂O₃ a été étudiée entre 1 et 30 bars de pression et à des températures de réaction comprises entre 200 et 275°C. L'activité et la sélectivité ont été mesurées en fonction du temps de réaction, conjointement à la caractérisation physico-chimique in situ du fer en volume par spectroscopie Mossbauer et mesures magnétiques, et des espèces superficielles par spectroscopie infra-rouge, thermodésorption programmée et thermoréduction programmée. Les résultats obtenus pour la réaction H₂ + CO ont conduit à l'élaboration d'un mécanisme basé sur la dissociation initiale du monoxyde de carbone, et croissance de chaîne par addition successive d'espèces CH_x (x = 1, 2 ou 3). Le fer est rapidement transformé en carbure de fer Fe_(2+x)C (0 < x < 0,4) dont la teneur en carbone augmente en fonction du temps de réaction. Aucun oxyde de fer ne se forme en quantité décelable. Le vieillissement observé du catalyseur est attribué à la carburation du fer et à l'accumulation de carbone peu réactif. L'étude comparative de la réaction H₂ + CO₂ a mis en évidence l'évolution particulière de l'activité en fonction du temps selon un modèle en trois étapes successives (désactivation, réactivation, nouvelle désactivation) qui ont pu être interprétées à l'aide des études physico-chimiques in situ du catalyseur. L'effet de la pression totale des réactifs de 8 à 30 bars sur l'orientation des sélectivités a été établi. Des alcools homologues sont produits préférentiellement aux hydrocarbures dans certaines conditions de la réaction H₂ + CO, et en particulier : le méthanol à 200-225°C et dès 8 bars de pression. Avec la réaction H₂ + CO₂, les produits prépondérants sont le méthane et le méthanol. L'ensemble des résultats obtenus entre 1 et 30 bars a conduit à l'élaboration d'un schéma réactionnel faisant intervenir le monoxyde de carbone sous forme dissociée pour la production d'hydrocarbures, et simultanément sous forme moléculaire pour la production d'alcools. La nature des sites actifs est discutée.

Inligting en kommunikasietegnologie (IKT) vorm ‘n belangrike komponent van effektiewe onderrig en leer. Ten spyte van die gedokumenteerde voordele wat IKT vir onderrig en leer inhou, bly IKT–integrering in skole steeds gebrekkig. Die implementering van IKT om onderrig en leer oor ‘n wye reeks van leerareas te bevorder en uit te brei, blyk ‘n groot uitdaging by meeste skole te wees. Faktore soos fiskale verpligtinge, ruimtelike hindernisse, ondoeltreffende en gebrekkige infrastruktuur en swak koördinering ondermyn meeste pogings tot effektiewe en volhoubare IKT–gebruik. Onderwysers wat begin het om IKT in hul onderrigpraktyke toe te pas, verlang verskillende vorms van ondersteuning, insluitend die van tegniese en implementeringsondersteuning. Die SITES modules help om die pad na volhoubare IKT–gebruik in Suid–Afrika aan te dui deur die vernaamste studies plaaslik en internasionaal uiteen te sit, beste praktyke te beklemtoon en die noodsaaklikheid van tegnologiekoördineerders te bevestig. Die doel van die navorsing is gefokus op die rol wat die tegnologiekoördineerder vertolk in die implementering en benutting van IKT in Suid Afrikaanse skole. Hierdie inligting kan nuttig wees om huidige onderrig en leerpraktyke in oënskou te neem en om ingeligte besluite rakende effektiewe en volhoubare IKT–gebruik in onderrig en leer te neem. Die studie is gebaseer op die bevindinge van die derde SITES studie (SITES 2006), wat ‘n internasionale kwantitatiewe opname oor die pedagogiese praktyke en gebruike van IKT met betrekking tot die 21ste eeuse leervaardighede in skole. Die studie het ‘n SDA metodologie van die Suid Afrikaanse tegnologiekoördineerders gevolg. Aangesien Suid–Afrika aan al drie studies deelgeneem het kon uit die literatuur longitudinale tendense aangedui word met betrekking tot IKT–gebruik in Suid–Afrikaanse skole. Tydens die SDA is beskrywende statistiek uitgevoer en kruistabulerings bereken om betekenisvolle korrelasies tussen veranderlikes te bepaal. Alhoewel meeste tegnologiekoördineerders aangetoon het dat die gebruik van IKT relevant is binne hulle skole, is die vlak van IKT–gebruik binne vakverband besonder laag weens talle struikelblokke wat die gebruik van IKT in skole belemmer. Daar is ‘n beperkte hoeveelheid rekenaars en skootrekenaars beskikbaar per skool. By die meeste skole tree onderwysers op as tegnologiekoördineerders wat ook dan verantwoordelikheid aanvaar vir die instandhouding van die rekenaars. Die tegnologiekoördineerder se pligte en verantwoordelikheid bestaan hoofsaaklik uit die onderrig van ander vakke en relatief min tyd word gewy aan IKTkursusse vir leerders en onderwysers, en juis daarom is die formele rol wat die tegnologiekoördineerder vertolk betreklik laag. Hoewel onderwysers in die meeste skole optree as tegnologiekoördineerders, ontvang hulle kommerwekkend min professionele onderwysersontwikkeling (POO). Die studie toon aan dat onderwysers onvoldoende tegniese ondersteuning ontvang. Tegnologiekoördineerders het betreklik min periodes per week tot hul beskikking om IKT–ondersteuning aan te bied. Prakties betekenisvolle korrelasies tussen die gebruik van IKT in die onderrig en leer van leerareas hang af van die beskikbaarheid van IKT–toerusting. Die gebruik van IKT in die onderrig en leer van leerareas, is in ‘n sekere mate afhanklik van die beskikbaarheid van IKT ondersteuning vir meeste van die verskillende aktiwiteite wat by skole plaasvind. Vir effektiewe en volhoubare IKT–gebruik is dit belangrik dat die onderwysers tegniese– en POO ontvang en dit sal vereis dat die tegnologiekoördineerder ‘n meer prominente rol vervul in Suid Afrikaanse skole. Tegnologiekoördineerders speel ‘n toonaangewende rol in die koördinering, instandhouding, ondersteuning en bemagtiging van fasiliteite en gebruikers by onderwysinstellings. / Thesis (M.Ed.)--North-West University, Potchefstroom Campus, 2012.

Inligting en kommunikasietegnologie (IKT) vorm ‘n belangrike komponent van effektiewe onderrig en leer. Ten spyte van die gedokumenteerde voordele wat IKT vir onderrig en leer inhou, bly IKT–integrering in skole steeds gebrekkig. Die implementering van IKT om onderrig en leer oor ‘n wye reeks van leerareas te bevorder en uit te brei, blyk ‘n groot uitdaging by meeste skole te wees. Faktore soos fiskale verpligtinge, ruimtelike hindernisse, ondoeltreffende en gebrekkige infrastruktuur en swak koördinering ondermyn meeste pogings tot effektiewe en volhoubare IKT–gebruik. Onderwysers wat begin het om IKT in hul onderrigpraktyke toe te pas, verlang verskillende vorms van ondersteuning, insluitend die van tegniese en implementeringsondersteuning. Die SITES modules help om die pad na volhoubare IKT–gebruik in Suid–Afrika aan te dui deur die vernaamste studies plaaslik en internasionaal uiteen te sit, beste praktyke te beklemtoon en die noodsaaklikheid van tegnologiekoördineerders te bevestig. Die doel van die navorsing is gefokus op die rol wat die tegnologiekoördineerder vertolk in die implementering en benutting van IKT in Suid Afrikaanse skole. Hierdie inligting kan nuttig wees om huidige onderrig en leerpraktyke in oënskou te neem en om ingeligte besluite rakende effektiewe en volhoubare IKT–gebruik in onderrig en leer te neem. Die studie is gebaseer op die bevindinge van die derde SITES studie (SITES 2006), wat ‘n internasionale kwantitatiewe opname oor die pedagogiese praktyke en gebruike van IKT met betrekking tot die 21ste eeuse leervaardighede in skole. Die studie het ‘n SDA metodologie van die Suid Afrikaanse tegnologiekoördineerders gevolg. Aangesien Suid–Afrika aan al drie studies deelgeneem het kon uit die literatuur longitudinale tendense aangedui word met betrekking tot IKT–gebruik in Suid–Afrikaanse skole. Tydens die SDA is beskrywende statistiek uitgevoer en kruistabulerings bereken om betekenisvolle korrelasies tussen veranderlikes te bepaal. Alhoewel meeste tegnologiekoördineerders aangetoon het dat die gebruik van IKT relevant is binne hulle skole, is die vlak van IKT–gebruik binne vakverband besonder laag weens talle struikelblokke wat die gebruik van IKT in skole belemmer. Daar is ‘n beperkte hoeveelheid rekenaars en skootrekenaars beskikbaar per skool. By die meeste skole tree onderwysers op as tegnologiekoördineerders wat ook dan verantwoordelikheid aanvaar vir die instandhouding van die rekenaars. Die tegnologiekoördineerder se pligte en verantwoordelikheid bestaan hoofsaaklik uit die onderrig van ander vakke en relatief min tyd word gewy aan IKTkursusse vir leerders en onderwysers, en juis daarom is die formele rol wat die tegnologiekoördineerder vertolk betreklik laag. Hoewel onderwysers in die meeste skole optree as tegnologiekoördineerders, ontvang hulle kommerwekkend min professionele onderwysersontwikkeling (POO). Die studie toon aan dat onderwysers onvoldoende tegniese ondersteuning ontvang. Tegnologiekoördineerders het betreklik min periodes per week tot hul beskikking om IKT–ondersteuning aan te bied. Prakties betekenisvolle korrelasies tussen die gebruik van IKT in die onderrig en leer van leerareas hang af van die beskikbaarheid van IKT–toerusting. Die gebruik van IKT in die onderrig en leer van leerareas, is in ‘n sekere mate afhanklik van die beskikbaarheid van IKT ondersteuning vir meeste van die verskillende aktiwiteite wat by skole plaasvind. Vir effektiewe en volhoubare IKT–gebruik is dit belangrik dat die onderwysers tegniese– en POO ontvang en dit sal vereis dat die tegnologiekoördineerder ‘n meer prominente rol vervul in Suid Afrikaanse skole. Tegnologiekoördineerders speel ‘n toonaangewende rol in die koördinering, instandhouding, ondersteuning en bemagtiging van fasiliteite en gebruikers by onderwysinstellings. / Thesis (M.Ed.)--North-West University, Potchefstroom Campus, 2012.

Dans le cadre de cette thèse, nous nous proposons d'examiner le comportement de deux silices bi-fonctionnalisées présentant une mésostructure (i.e., MCM-41) ou non (i.e., gel de silice, dénommé ici SiO2), ainsi que leur réactivité vis-à-vis des espèces de chrome. Les groupements fonctionnels sélectionnés pour modifier les échantillons de silice afin d'atteindre ce but sont d'une part, le mercaptopropyle et l'acide propylsulfonique (MCM-SH,SO3H), et d'autre part le mercaptopropyle et l'éthylènediaminetriacetate (SiO2-SH/ED3A). La recherche a débuté avec des matériaux structurellement ordonnés, de type MCM-41, offrant une très grande aire spécifique tout en assurant un accès rapide et aisé vers les groupements fonctionnels. Sur la base d'une MCM-41 modifiée par des fonctions thiol oxydées à divers degrés, un ensemble d'échantillons d'adsorbants caractérisés par différents rapport de groupements greffés thiol/acide sulfonique (teneur constante en soufre = 1 mmol g-1) ont été synthétisés. Une attention particulière a été portée à la caractérisation de la composition chimique de surface, pour laquelle on s'attend à une forte influence sur les propriétés de sorption. Une méthode simple, basée sur une seule technique instrumentale (titrage conductimétrique), a été appliquée pour la détermination simultanée des groupements thiol et sulfonique sur MCM-SH,SO3H. Dans un second temps, les conditions expérimentales susceptibles de permettre un piégeage effectif de Cr(VI) sur MCM-SH,SO3H ont été définies, en étudiant notamment l'effet du pH, du rapport solide/solution, ou encore de la composition de l'adsorbant (i.e., rapport SH/SO3H). Sur la base des données collectées, un mécanisme de réduction-sorption expliquant le processus d'immobilisation a été proposé. Dans une seconde approche, un autre type de silice bi-fonctionnelle (SiO2-SH,ED3A) a été suggéré afin d'améliorer l'affinité (propriétés de sorption) du matériau vis-à-vis des espèces Cr(III) générées lors de la réduction de Cr(VI). Le gel de silice a été choisi comme matrice pour greffer des quantités contrôlées de groupements mercaptopropyls et éthylènediaminetriacetate à sa surface. La performance de tel adsorbants bi-fonctionnels a été évaluée au regard de paramètres expérimentaux variés susceptibles d'influencer le processus de sorption-réduction (pH, rapport solide/solution, concentration) afin de déterminer le mécanisme de séquestration et de le comparer avec les adsorbants précédents. Finalement, on montrera comment le second adsorbant présente également l'avantage de pouvoir être utilisé dans des conditions dynamiques (expériences en colonne) / The present work proposes to examine chemical characteristics and behavior of two bifunctionalized silicas exhibiting either a mesostructure (i.e., MCM-41) or not (i.e., silica gel, denoted here SiO2) with respect to the immobilization of chromium species. The organo-functional groups selected to achieve this goal are mercaptopropyl and propylsulfonic acid moieties (MCM-SH,SO3H), on one hand, and mercaptopropyl and ethylenediaminetriacetate groups (SiO2-SH/ED3A) on the other hand. The research has been started with structurally ordered materials, of MCM-41 type, to ensure high surface area and easy and fast accessibility to the functional groups. On the basis of thiol-modified MCM-41, a set of sorbent samples containing different ratio of grafted mercaptopropyl and propylsulfonic acid groups (constant concentration of sulfur = 1 mmol g-1) has been synthesized. Special attention was first given to the characterization of surface chemical contents, which are expected to have a strong influence on sorption parameters. A simple, one-instrument method (conductometric titration) has been applied to the simultaneous determination of thiol- and sulfonic group on MCM-SH,SO3H. Then, the experimental conditions that are likely to provide effective sequestration of Cr(VI) on MCM-SH,SO3H have been defined, notably by studying the effect of pH, solid-to-solution ratio, or composition of the adsorbent (i.e., SH/SO3H ratio). On the basis of received data, a reduction-sorption mechanism explaining the uptake process has been proposed. In a second approach, a second type of bi-functional silica (SiO2-SH,ED3A) was suggested so as to improve the affinity (sorption properties) of the material to the reductively-generated Cr(III) species. Silica-gel was chosen as the matrix to graft controlled amounts of mercaptopropyl and ethylenediaminetriacetate groups at its surface. The performance of such bi-functional adsorbent was evaluated with respect to various experimental parameters likely to affect the reduction-sorption process (pH, solid-to-solution ratio, concentration) in order to determine the uptake mechanism and to compare it with the above adsorbent. Finally, it will be seen how this second adsorbent also offers the advantage of being usable in flowing conditions (column experiments)

The solid-state mesoscopic solar cells (sMSCs) have been developed as a promising alternative technology to the conventional photovoltaics. However, the device performance suffers from the low hole-mobilities and the incomplete pore filling of the hole transport materials (HTMs) into the mesoporous electrodes. A variety of HTMs and different preparation methods have been studied to overcome these limitations. There are two types of sMSCs included in this doctoral thesis, namely solid-state dye-sensitized solar cells (sDSCs) and organometallic halide perovskite based solar cells. Two different types of HTMs, namely the small molecule organic HTM spiro-OMeTAD and the conjugated polymer HTM P3HT, were compared in sDSCs. The photo-induced absorption spectroscopy (PIA) spectra and spectroelectrochemical data suggested that the dye-dye hole conduction occurs in the absence of HTM and appears to be of significant importance to the contribution of hole transport. The PIA measurements and transient absorption spectroscopy (TAS) indicated that the oxidized dye was efficiently regenerated by a small molecule organic HTM TPAA due to its excellent pore filling. The conducting polymer P3HT was employed as a co-HTM to transfer the holes away from TPAA to prohibit the charge carrier recombination and to improve the hole transport. An alternative small molecule organic HTM, MeO-TPD, was found to outperform spiro-OMeTAD in sDSCs due to its more efficient pore filling and higher hole-mobility. Moreover, an initial light soaking treatment was observed to significantly improve the device performance due to a mechanism of Li+ ion migration towards the TiO2 surface. In order to overcome the infiltration difficulty of conducting polymer HTMs, a state-of-the-art method to perform in-situ photoelectrochemical polymerization (PEP) in an aqueous micellar solution of bis-EDOT monomer was developed as an environmental-friendly alternative pathway with scale-up potential for constructing efficient sDSCs with polymer HTMs. Three different types of HTMs, namely DEH, spiro-OMeTAD and P3HT, were used to investigate the influence of HTMs on the charge recombination in CH3NH3PbI3 perovskite based sMSCs. The photovoltage decay measurements indicate that the electron lifetime (τn) of these devices decreases by one order of magnitude in the sequence τspiro-OMeTAD &gt; τP3HT &gt; τDEH.

This thesis studies the interaction between the bare Cu{311} surface with NO and NH3,individually and co-adsorbed using reflection-absorption infrared spectroscopy (RAIRS). In addition to the bare Cu{311} surface, the interaction of NO and NH3 with the various oxygen phases of the Cu{311} surface phases was also studied. Several other techniques were used in tandem to support the study, such as low energy electron diffraction (LEED) and temperature programmed desorption (TPD) experiments using mass spectrometry. The study was carried out in pursuit an understanding of the underlying mechanism of the selective catalytic reduction (SCR) of NO using NH3 in current diesel engines. The dosing of NO onto the Cu{311} surface at 100 K leads to the initial adsorption of intact NO. After an exposure threshold is reached, individual NO molecules react with another NO molecule to form (NO)2 dimers. These dimer species subsequently form N2O, leaving O(a) on the surface. Oxygen was found to be an inhibitor for the reaction, either due to the reaction in a self-poisoning process or from oxygen pre-dosing onto the Cu{311} surface. Temperature plays a minor role with regards to NO/Cu{311}, as it only affects the amount of NO on the surface along with adsorbate surface mobility. Similarly, NH3 was found to adsorb intact onto the Cu{311} surface and not to react or dissociate at 100 K. Oxygen acts as a site blocker for the adsorption, but can also stabilise NH3 to remain on the surface at higher temperatures due to electronic effects. At 300 K, it was found that both the bare and oxygen pre-covered Cu{311} surface was able to dissociate NH3 into NH2. The co-adsorption of NO and that of NH3 onto the Cu{311} surface were found to be largely independent of each other and the interaction is dominated by the displacement of NO by NH3. However, as NO adsorption on the Cu{311} surface forms O(a), it indirectly affects the adsorption of NH3 by creating an oxygen covered Cu{311} surface, which changes how NH3 adsorbs onto the surface.