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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
91

Grassroots Resistance Against Urban Renewal: The Case Of Guzeltepe, Istanbul

Ergin, Nezihe Basak 01 January 2007 (has links) (PDF)
The aim of this study is to contribute to the urban social movement literature of Turkey which is lacking particularly for &ldquo / gecekondu resistance&rdquo / and to reveal and study the gecekondu resistance as a grassroots movement against the demolition of gecekondus, in the name of urban renewal projects in Istanbul, especially since 2004. It also investigates the &ldquo / urban social movement&rdquo / concept whose meaning is under discussion in the literature due to its usage in different aspects of resistance in the urban area. The literature review focuses mainly on the production of space, focusing particularly on urban renewal, urban resistance and social movements especially reflecting on the theoretical perspectives of prominent scholars like Lefebvre and Castells. The research focuses on neighborhood resistance in gecekondu areas / however in an attempt to make a categorization of ways of urban resistance in Istanbul. This thesis is based upon the field study pursued in the period between January and October 2006, in G&uuml / zeltepe neighborhood, in Ey&uuml / p, being a remarkable example of resistance for various reasons which will be elaborated in the thesis. G&uuml / zeltepe which is a part of the urban renewal project in Istanbul is investigated with participant observation and in-depth interviews comprising people both participating directly in the resistance and &ldquo / ordinary&rdquo / dwellers, who do not have political affiliations. The study is supported by a systematic analysis of representations of gecekondu resistance and its demolition in the Turkish press, from July 2005 until August 2006.
92

Activity Of Carbon Supported Platinum Nanoparticles Catalysts Toward Methanol Oxidation Reaction: Role Of Metal Precursor And A New Surfactant

Sen, Selda 01 February 2008 (has links) (PDF)
In this thesis, carbon supported platinum nanoparticle catalysts were prepared using PtCl4 and H2PtCl6 as starting materials and 1-heptanethiol, tert-nonyl mercaptan, 1-hexadecanethiol, 1-octadecanethiol as surfactants. These new catalysts were employed for methanol oxidation reaction which are used for direct methanol fuel cells. Tert-nonyl mercaptane was used for the first time in this type of reaction and the other surfactants were used for comparison of the catalysts performance. Cyclic voltammetry (CV), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD) and transmission electron microscopy (TEM) were used in order to determine the nature of the catalysts. The average platinum crystallite particle sizes of all prepared catalysts were determined by both X-ray diffraction and transmission electron microscopy. It was found that platinum crystallizes in face-centered cubic structure and the surfactant play an important role on the size of platinum nanoparticles, branch surfactant, such as tert-nonyl mercaptane, causes an increase in the size of platinum nanoparticles, about 3 nm, compared to linear surfactant, such as 1-heptanethiol, about 2 nm. The oxidation states of platinum and their ratios were determined by XPS technique. These results indicated that platinum has two different oxidation states, zero and +4, and Pt(0) to Pt(IV) ratio is about 7.5 to 2.5. In addition to this, O 1s region of XPS was also examined and found that the surface of all of the catalysts covered by adsorbed hydroxide except the catalyst which was prepared by PtCl4 and tert-nonyl mercaptane (Catalyst IIa), where adsorption of water were observed and the catalyst which was prepared by H2PtCl6 and tert-nonyl mercaptane (Catalysts IIb), where adsorption of 65% of hydroxide and 35% of water were identified. Electrochemical studies indicated that Catalyst IIa has the maximum activity (&amp / #61566 / 342 A/gPt at 0.612 V) towards methanol oxidation reaction while Catalyst IIIb (H2PtCl6 and 1-hexanethiol were used to prepare this catalyst) has the minimum activity (&amp / #61566 / 91A/gPt at 0.580V). XRD, TEM and XPS results indicated that the optimum catalyst for methanol oxidation reaction contains about 3 nm of platinum nanoparticles, adsorbed hydroxide and water on the surface of catalyst, but sulphur. These results are in agreement with the proposed mechanism.
93

Effect Of Stabilizer On The Catalytic Activity Of Cobalt(0) Nanoclusters Catalyst In The Hydrolysis Of Sodium Borohydride

Kocak, Ebru 01 December 2009 (has links) (PDF)
The development of new storage materials will facilitate the use of hydrogen as a major energy carrier in near future. Among the chemical hydrides used as hydrogen storage materials for supplying hydrogen at ambient temperature, sodium borohydride seems to be an ideal one because it is stable under ordinary conditions and liberates hydrogen gas in a safe and controllable way in aqueous solutions. However, self hydrolysis of sodium borohydride is so slow that requires a suitable catalyst. This work aims the use of water dispersible cobalt(0) nanoclusters having large portion of atoms on the surface as catalyst for the hydrolysis of sodium borohydride. In-situ formation of cobalt(0) nanoclusters and catalytic hydrolysis of sodium borohydride were performed starting with a cobalt(II) chloride as precursor and sodium borohydride as reducing agent and substrate in the presence of a water soluble stabilizer. As stabilizer, water soluble polyacrylic acid as well as hydrogen phosphate ion were tested. Cobalt(0) nanoclusters were characterized by using all the available analytical methods including FT-IR, TEM, XPS, UV-visible electronic absorption spectroscopy. The kinetics of cobalt(0) nanoclusters catalyzed hydrolysis of sodium borohydride were studied depending on the catalyst concentration, substrate concentration, stabilizing agent concentration and temperature.
94

Carbon Supported Platinum-palladium Catalysts For Methanol And Ethanol Oxidation Reactions

Ozturk, Zafer 01 February 2011 (has links) (PDF)
In this work, two groups of carbon supported Pt-Pd catalysts have been prepared in order to investigate the effect of Pd, as a second metal, and surfactants on the catalytic activity towards methanol and ethanol oxidation reactions used in the direct methanol and ethanol fuel cells. In the first group (group a), 1- hexanethiol was used as a stabilizing agent while in the second group (group b), 1,1 dimethyl hexanethiol was utilized. Cyclic voltammetry (CV), chronoamperometry (CA), X-ray diffraction (XRD), transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS) were used in order to determine the nature of the catalysts. The average crystalline size of the metal particles in the catalysts was explored by XRD and TEM. TEM results revealed the uniform distribution of the metal nanoparticles on carbon support with a narrow size distribution in the range of 3.0 to 3.7 nm and the average crystalline sizes of metal particles for group &ldquo / b&rdquo / catalysts were larger than that of group &ldquo / a&rdquo / catalysts which can be explained by the surfactant effect. These results were in good agreement with XRD data. The oxidation states of platinum (Pt(0) and Pt(IV)) and palladium (Pd(0) and Pd(II)) and their ratios were investigated by XPS and for the most active catalyst, catalyst Ib, these ratios were found to be as 6.94 and 13.7, respectively. Electrochemical activities of the catalysts towards methanol and ethanol oxidation reactions were recorded and compared with that of Pt/C and the commercial Pt (ETEK 20 %wt) catalysts. The results indicated that the group &lsquo / b&rsquo / catalyst has greater catalytic activities than that of group &lsquo / a&rsquo / catalysts. Catalyst Ib comes into prominence as the most active catalyst due to its superior characteristics that it possess such as highest extent of alloying with respect to the palladium amount used, active surface area, CO-tolerance, stability and Pt (0) to Pt (IV) and Pd (0) to Pd (II) ratios.
95

Synthesis And Characterization Of Ruthenium(0) Metal Nanoparticles As Catalyst In The Hydrolysis Of Sodium Borohydride

Zahmakiran, Mehmet 01 April 2005 (has links) (PDF)
Sodium borohydride is stable in alkaline solution, however, it hydrolyses and generates hydrogen gas in the presence of suitable catalyst. By this way hydrogen can be generated safely for the fuel cells. All of the catalyst having been used in the hydrolysis of sodium borohydride, with one exception, are heterogeneous. The limited surface area of the heterogeneous and therefore, have limited activity because of the surface area. Thus, the use of metal nanoclusters as catalyst with large surface area is expected to provide a potential route to increase the catalytic activity. In this dissertation we report for the first time the use of ruthenium(0) nanoparticles as catalyst in the hydrolysis of sodium borohydride. The water dispersible ruthenium(0) nanoparticles were prepared by the reduction of RuCl3.xH2O with sodium borohydride and were stabilized by three different ligands dodecanethiol, ethylenediamine and acetate. Among these three colloidal materials the acetate stabilized ruthenium(0) nanoparticles were found to have the highest catalytic activity in catalyzing the hydrolysis of sodium borohydride. The acetate stabilized ruthenium(0) nanoparticles were characterized by tranmission electron microscopy (TEM), X-ray photoelectron spectroscopy and FT-IR spectroscopy. The particle size of the acetate stabilized ruthenium(0) nanoparticles was determined to be 2.62&plusmn / 1.18 nm from the TEM analysis. The kinetic of the ruthenium(0) nanoparticles catalyzed hydrolysis of sodium borohydride was studied depending on the catalyst concentration, substrate concentration and temperature. The activation parameters of this reaction were also determined from the evaluation of the kinetic data. This catalyst provides the lowest activation energy ever found for the hydrolysis of sodium borohydride.
96

Synthesis Of Ti, Cr, Mn, Fe, Co, Ni, Cu, Zn Sulfides By Solid-gas Reactions, Investigation Of Structural And Conducting Properties

Genisel, Mustafa Fatih 01 November 2003 (has links) (PDF)
In this study some of the first row transition metal oxides were transformed to metal sulfides by new solid gas reaction system. Transition metal sulfides have wide application area in industry and technology. Several techniques are known for the production of metal sulfides. Such as reactions between metal or metal oxide with H2S, precipitation in several liquid medium, reaction between metal and sulfur in closed vessel, chemical vapor deposition (CVD) technique. These techniques will have some disadvantages / for example, reactants are rarely available or expensive materials, their production systems are complicated and hard to set up these systems, products contain oxygen or hydrogen or corresponding metal sulfate as impurities. In our new sulfidizing system the reactants are metal oxides, carbon and SO2. These materials can be found easily. Especially, SO2 usage in this system is a big advantage of giving possibility of usage the hazardous waste product of SO2 in industry. The sulfidizing gas mixture was obtained by passing SO2 over activated carbon at 750 OC in a vertical tubular furnace. The obtained gas contains, mainly, CS2, CO and COS. The sulfidizing reactions took place in the horizontal tubular furnace at 450OC-1250 OC. The duration of the reaction, (three hours), and flow rate (60ml/min) of the SO2 gas were kept constant. The products were examined by X-ray powder diffraction and Raman scattering spectroscopy. All examined metal oxides were transformed to metal sulfides by sulfidizing gas mixture successfully. Ti3S5 was obtained from TiO2. Cr2S3 was obtained from Cr2O3. MnS (Alabandite) was obtained from MnO2. FeS and Fe1-xS (Pyrrhotite) were obtained from Fe2O3. Co9S8 (Cobaltpentlandite) and CoS (Jaipurite) were obtained from Co3O4. NiS was obtained from NiO. Cu7.2S, Cu1.6S (Calcocite-Q), Cu1.81S, Cu7S4 (Anilite) Cu9S5 (Digenite), Cu8S5 (Geerite) were obtained from CuO, ZnS was obtained from ZnO. The electrical conductivity character of each product obtained by sulfidizing reaction was analyzed in the temperature range of 77 K-300 K. Titanium sulfide, cobalt sulfide and nickel sulfide showed metallic conductivity, cupper sulfide and iron sulfide showed semiconductor behavior in this temperature range.
97

Synthesis And Characterization Of Hydrogenphosphate-stabilized Nickel(0) Nanoclusters As Catalyst For The Hydrolysis Of Sodium Borohydride

Metin, Onder 01 May 2006 (has links) (PDF)
The development of new storage materials will facilitate the use of hydrogen as a major energy carrier in near future. In hydrogen economy, chemical hydrides such as NaBH4, KBH4, LiH, NaH have been tested as hydrogen storage materials for supplying hydrogen at ambient temperature. Among these chemical hydrides, sodium borohydride seems to be an ideal hydrogen storage material because it is stable under ordinary conditions and liberates hydrogen gas in a safe and controllable way in aqueous solutions. However, self hydrolysis of sodium borohydride is so slow that it requires a suitable catalyst. All of the prior catalysts tested for the hydrolysis of sodium borohydride are heterogeneous and, therefore, have limited activity because of the small surface area. Here, we report for the first time the employment of water dispersible metal(0) nanoclusters having a large portion of atoms on the surface as a catalyst for the hydrolysis of sodium borohydride. In-situ formation of nickel(0) nanoclusters and catalytic hydrolysis of sodium borohydride were performed in the same medium. Nickel(0) nanoclusters are prepared from the reduction of nickel(II) acetylacetonate by sodium borohydride in aqueous solution and stabilized with hydrogenphosphate anions. The nickel(0) nanoclusters were characterized by using XPS, Powder XRD, FT-IR, UV-Vis and NMR spectroscopic methods. The kinetics of the nickel(0) nanoclusters catalyzed hydrolysis of sodium borohydride was studied depending on the catalyst concentration, substrate concentration, stabilizing agent concentration and temperature. Tha kinetic study shows that the nickel(0) nanocluster-catalyzed hydrolysis of sodium borohydride is first order with respect to catalyst concentration and zero order with respect to substrate concentration The activation parameters of this reaction were also determined from the evaluation of the kinetic data. The hydrogenphosphate-stabilized nickel(0) nanoclusters provide a lower activation energy (Ea= 55 kJ/mol) than bulk nickel (Ea=73 kJ/mol) for the hydrolysis of sodium borohydride.
98

Sex and society in the 'Laws' of Plato

Moore, Kenneth R. January 2003 (has links)
This thesis deals with the topics of sex and society in the Laws of Plato with recourse to ancient historical context and modern critical theory. It examines reconstructions of ancient 'sexuality' (e.g. through Dover, Foucault and Davidson) with a view to increased clarification. The text of the Laws is considered, along with many of its literary qualities, its influences and the utopian plan that it entails. Plato's narrator, the Athenian Stranger, has proposed the remarkable theory that sexuality can be controlled through the manipulation of people's thoughts. The thesis is particularly interested in the manner in which sexuality is ideologically constructed. A significant portion of this inquiry deals with education in the hypothetical polis (Magnesia) and the part that this is designed to play specifically in terms of sex-role stereotyping. The Laws spins andreia as the ideal model for the Magnesians to imitate in their mandatory pursuit of arete. The reformulation of the Magnesian oikos and the 'brave new femininity' that this plan entails figure prominently into this examination. Magnesian women must become more like (idealised) men in terms of 'manly' enkrateia. They will combine alleged elements from athenian, Spartan, Kretan, Sauromatian and Amazonian women (plus Platonic philosophy) to attain this new status. Men must become less like women are perceived to be. A law is drafted to ban same-sex activities, considered 'womanish', but there is some uncertainty as to whether or not it will ever be enforced. Psychology and propaganda, religion, education, the family and government will all work together to affect the moral hygiene of Magnesia. The thesis investigates each of these topics, with recourse to material outside the Laws, in considering Plato's social/sexual construction theory.
99

Sur l'application de la théorie des réseaux à la φιλία grecque-Essai de reconstruction de réseaux de φιλία à la lumière des relations extérieures de Thasos (VIIe - Ier siècle a.C.)

Jolin, David 24 April 2018 (has links)
La notion de φιλία, communément traduite par le terme amitié, constituait un enjeu important dans les sociétés grecques. Alors qu’elle était synonyme de vertu et de justice à la période archaïque, la φιλία devint, sous la plume des philosophes des Ve et IVe siècles, un gage de dévouement et de fidélité, ainsi qu’un concept complémentaire aux principes de l’utilité et du plaisir. Elle servit aussi, en particulier dans le contexte de la période hellénistique, à consolider et à renforcer les relations diplomatiques des cités, des monarchies et de Rome. En se fondant sur l’exemple de Thasos, ce mémoire propose d’approfondir les dimensions sociétale et internationale de la φιλία en regard des témoignages littéraires et épigraphiques. Dans le but d’apporter une contribution originale, la φιλία est étudiée sous l’angle de la théorie des réseaux, qui permet de comprendre la portée et les implications du concept dans les rapports extérieurs de Thasos.
100

Le culte d'Homonoia dans les cités grecques

Thériault, Gaétan 13 April 2018 (has links)
Chez les Grecs, le mot employé pour désigner la concorde était homonoia, qui signifie littéralement: la conformité des sentiments, l'unanimité, l'harmonie. Ce mot sous-entend nécessairement la présence d'un conflit. Or, les Grecs, comme cela était coutume chez eux, déifièrent cette abstraction pour recourir au pouvoir qui en émanait. L'objet de cette recherche consiste donc à présenter, étudier, analyser et commenter tous les témoignages relatifs au culte d'Homonoia dans la Grèce ancienne. Une telle étude permettra d'établir l'apparition du culte, son développement, ses modalités, sa répartition géographique, ses sanctuaires, ses temples, ses autels, ses prêtres et enfin ses liens souvent marquants avec les grands événements de l'histoire grecque, dont la trame est une suite presque ininterrompue de conflits, de guerres et de dissensions. / Québec Université Laval, Bibliothèque 2013

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