As formulações de eletrocatalisadores Pt:(Ce0,9Y0,1O2)+Pt/C Etek, Pt:(Ce0,9Ru0,1O2)+Pt/C Etek, Pt:Ce0,9Y0,1O2/C e Pt:Ce0,9Ru0,1O2+RuO2/C foram preparados pelo método da redução por álcool e caracterizados por difração de raios X (DRX) e microscopia eletrônica de transmissão (MET). A tolerância ao CO foi estudada utilizando o stripping de CO e medidas de curvas de polarização em células unitárias alimentadas com misturas de H2/CO no ânodo e oxigênio no cátodo, na temperatura de 80ºC e pressão absoluta de 2 bar para ânodo e cátodo. Os testes em células a combustível tipo PEMFC mostraram que a oxidação do CO adsorvido a CO2 na superfície da platina ocorre em potenciais menos positivos quando comparado com o catalisador comercial, Pt/C Etek, mostrando tolerância ao CO adsorvido nos eletrocatalisadores de Pt:Ce0,9Y0,1O2/C e Pt:(Ce0,9Ru0,1O2+RuO2)/C. / Pt:(Ce0,9Y0,1O2)+Pt/C Etek, Pt:(Ce0,9Ru0,1O2)+Pt/C Etek, Pt:Ce0,9Y0,1O2/C e Pt:Ce0,9Ru0,1O2+RuO2/C electrocatalysts, were prepared by an alcohol reduction process. The electrocatalysts were characterized by X-Ray Difratometry (XRD) end Transmission Electronic Microscopy (TEM). the CO tolerance was studied using CO stripping and measurements of polarization curves single-cell fed with H2/CO mixture at the anode and oxygen at the cathode, at a temperature of 85ºC and absolute pressure of 2 bar for anode and cathode. The results showed that the oxidation of CO adsorbed to CO2 on the surface of platinum occur at less positive potentials compared to Pt/C Etek showing the tolerance to CO adsorbed on these Pt:Ce0,9Y0,1O2/C e Pt:(Ce0,9Ru0,1O2+RuO2)/C electrocatalysts.

Magister Pharmaceuticae - MPharm / The objective was to prepare new solid phases, i.e. co-crystal forms, of two sulfa antibiotic drugs (sulfamethoxazole and sulfasalazine) with trimethoprim and fourteen potential co-formers with GRAS status. Trimethoprim was chosen for its synergistic effects with both sulfa drugs and the other co-formers were selected in an attempt to improve the physicochemical properties of the antibiotics. A variety of co-crystallization techniques, including solvent assisted grinding, slow evaporation, slurry method and solidification of the melt were used to obtain these results. From these methods, three new solid phases were successfully isolated for the sulfamethoxazole antibiotic, viz. sulfamethoxazole-benzoic anhydride (SMZ-BAN) co-crystal by the slurry method, amorphous sulfamethoxazole-trimethoprim (SMZ-TMP) form by solidification of the melt and amorphous sulfamethoxazole-oxalic acid (SMZ-OA) by slow evaporation. For the sulfasalazine antibiotic, co-crystallization experimentation produced, sulfasalazine-trimethoprim salt (SSZ-TMPs) by slow evaporation, sulfasalazine-trimethoprim co-crystal (SSZ-TMP) by solvent assisted grinding and sulfasalazine-nicotinamide co-crystal (SSZ-NC) by solidification of the melt. Of these six compounds subjected to single crystal X-ray analysis, only one of their structures was elucidated i.e. the salt, SSZ-TMPs. Different techniques that were used to assess the thermal behaviour of the products included hot stage microscopy, differential scanning calorimetry and thermogravimetric analysis. FTIR provided information on the purity of the compounds and the suggested host-guest interaction sites. X-ray powder diffraction supported the determination of the new phase comparative to the parent compounds. Finally dissolution testing was carried out for successful candidates with encouraging recommendations for future work.

京都大学 / 0048 / 新制・課程博士 / 博士(理学) / 甲第22684号 / 理博第4625号 / 新制||理||1665(附属図書館) / 京都大学大学院理学研究科化学専攻 / (主査)教授 北川 宏, 教授 吉村 一良, 教授 有賀 哲也 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DGAM

Cette étude concerne la valorisation du dioxyde de carbone par le procédé de méthanation. Elle vise à mettre au point des catalyseurs efficaces pour cette réaction. L'espèce active est le nickel métallique. Différents supports ont été étudiés tels que SiO₂, Al₂O₃, MgO, Y₂O₃ et CeO₂. Ces catalyseurs ont été préparés par la méthode d'imprégnation à sec. Dans un premier temps, les différents catalyseurs ont été caractérisés par différentes techniques physico-chimiques dont la Diffraction des Rayons X (DRX), la Réduction en Température Programmée (RTP-H₂), la Désorption en Température Programmée (DTP-CO₂), l'Adsorption d'Azote (méthode BET) et la Chimisorption d'Hydrogène. Dans un deuxième temps, les différents catalyseurs ainsi préparés ont été testés dans la réaction de méthanation du CO₂. Le catalyseur Ni/CeO₂ présente les meilleures performances catalytiques, parmi les systèmes étudiés. L'ajout du ruthénium améliore l'activité catalytique et la stabilité des catalyseurs. Le catalyseur Ru(0,5%)-Ni(5%)/CeO₂ est le plus performant, il présente une bonne activité catalytique et une bonne stabilité même pour une pression de 10 bar. Ceci le rend plus avantageux pour une application industrielle. / This study concerns the valorization of carbon dioxide by the methanation process. It aims to develop effectiv catalysts for this reaction. The active species is metallic nickel. Different supports have been studied such as SiO₂, Al₂O₃, MgO, Y₂O₃ and CeO₂. These catalysts were prepared by the dry impregnation method. Initially, the different catalysts were characterized by different physicochemical techniques including X-ray Diffraction (XRD), Temperature Programmed Reduction (TPR-H₂), Temperature Programmed Desorption (TPD-CO₂), nitrogen adsorption (BET method) and hydrogen chemisorption. In a second step, the various catalysts thus prepared were tested in the CO₂ methanation reaction. The Ni/CeO₂ catalysts has the best catalytic performance, among the systems studied. The addition of ruthenium improves the catalytic activity and the stability of the catalysts. The catalyst Ru(0.5%)-Ni(5%)/CeO₂ is the most efficient, it has good catalytic activity and good stability even as a pressure of 10 bar. This makes it advantageous for an industrial application.

No description available.

The Mo-nitrogenase complex is composed of two components, Fe-protein and MoFe-protein. This complex is able to catalyze the reduction of N2 through the MgATP dependent transfer of electrons from the Fe-protein Fe4S4 cluster to the MoFe-protein P-cluster and, subsequently, to the iron-molybdenum cofactor (FeMoco). FeMo-co is a Fe7S9MoC-(R)-homocitrate cluster and has two biosynthetic precursors, NifB-co and L-cluster, of unknown structure and composition. The biosynthesis of FeMo-co is an enigmatic process that minimally requires NifB, NifEN, Fe-protein, MoO4 2- , (R)-homocitrate and S-adenolsylmethionine. A means to isolate the NifB enzyme for characterization has been developed through use of a GST-fusion tag. Double recombination of A. vinelandii strains with a constructed vector has yielded strains capable of nif promoter regulated expression of GST-NifB. Extracts of strains containing GST-NifB were shown to activate the Monitrogenase complex in biochemical complementation assays. Mass spectroscopy was then used to verify successful isolation of GST-NifB by GSH-Sepharose affinity purification. The number of NifB-co ligand binding sites and ligand types were examined by EXAFS analysis of samples containing selenol and thiol ligands. A Fe6S9C model for NifB-co was optimized to best fit the EXAFS data, where a 2-fold discrepancy in binding sites implied by thiol or selenol only ligand samples suggests Fe-(μ2S)-Fe binding in the absence of Se. Samples containing heterogeneous ligand types indicated that NifX bound NifB-co ligates to four cysteine residues and one molecule of DTT.

Tvålärarsystem är ett arbetssätt som blir vanligare i svenska skolan. Det går ut på att två klass–eller ämneslärare delar på ansvaret för eleverna och dess tillhörande planering, undervisning och bedömning. Syftet med den här studien är att bidra med kunskap om hur tvålärarsystemet kan organiseras och genomföras i svensk kontext och hur arbetssättet ur ett lärarperspektiv påverkar undervisningen och möjligheter att möta elevernas behov. Det för att fylla den kunskapslucka som saknaden av svensk forskning kring tvålärarsystemet ger. I kapitlet tidigare forskning presenteras internationell forskning om tvålärarsystemet som kallas co-teaching. Då det saknas forskning om tvålärarsystemet i ett svenskt perspektiv kommer därför även beprövad dokumenterad erfarenhet om tvålärarsystem i Sverige att presenteras. Utifrån den tidigare forskningen framkommer två bärande begrepp ”kollegialt samarbete i klassrummet” samt ”gruppering”, dessa kommer ligga som ett teoretiskt raster över studien. I metodkapitlet beskrivs studiens tillvägagångssätt, beskrivning av informanterna, analysprocessen, etiska övervägande och en metoddiskussion. I resultatkapitlet presenteras informanternas beskrivning av undervisning och vilka konsekvenser det ger upphov till. Fokus ligger på vad den läraren som inte håller i undervisningen gör. I resultatet beskrivs även hur informanterna upplever att arbetssättet påverkar eleverna samt lärarnas möjlighet att möta elevernas behov. I diskussionsavsnittet förs resonemang kring resultatet i förhållande till den tidigare forskningen och de beprövade dokumenterade erfarenheter som presenterats i studien. Slutsatser utifrån studiens resultat är att lärarna är positivt inställda och upplever det lättare att möta elevernas behov, göra anpassningar och skapa en roligare och bättre undervisning. Det framkom att respondenterna saknar bevis för att tvålärarsystemet ökar elevernas måluppfyllelse men att alla har en känsla av att måluppfyllelsen ökar eftersom de känner att de kan möta fler elevers behov. En viktigt förutsättning för arbetssättet är att lärarnas samarbete fungerar. Ytterligare en viktig slutsats är att det behövs forskning om tvålärarsystemet ur ett svenskt perspektiv.

No description available.

The question is whether the legal framework for economic co-operation and integration in Africa, is suitable for achieving the aim of building the African Economic Community [AEC]. Economic integration, in leading to large markets and a supporting infrastructure, is a proper development strategy implementing which will depend on the efficacy of an enabling legal framework and a supportive multilateral trade system. The AEC is an integral part of the Organisation of African Unity [OAU]. Though largely a political organisation since inception way back in 1963, the OAU's agenda is increasingly economic, with the completion of de-colonisation, and will coincide with that of the AEC which is an economic and monetary union to be established in six stages through a merger of the regional economic communities [REC5]. To facilitate this merger, the aims, structure of organs and the entire legal framework of the RECs, need to be harmonised at the continental level. The structure for the AEC and the RECs gives pre-eminence to political organs, relegating the technical to making recommendations. In view of obstacles to African integration, such as inconsistent political will, effective technical organs ought to take charge of implementing the constitutive instruments and programmes. The AEC and RECs comply with the WTO Agreement. However, Article XXIV and Part IV of GATT need a proper interpretation, to guide parties. The Enabling Clause, dealing with regional trade agreements [RTAs] among developing countries, is the proper regime for notifying African RTAs; but as Africa is poised to develop and as the AEC is of indefinite duration, it is prudent that the RTAs comply with Article XXIV also. To develop a suitable legal framework, the protocols need to be drafted and adopted, and all the organs established. The constitutive instruments for the RECs need to be revised and implemented so that the stages for establishing the AEC are followed. An involved civil society and effective rules can improve prospects for the AEC.

No description available.