Urban tourism in Athens: tourist myths and images

This thesis explores and analyses the mythical quality of modem Athens as experienced by tourists. It is an exploration of the tourist gaze upon the Athenian landscape, as well as an account of how tourists narrate its urban mythology. This research is largely concerned with the relationship of time and space through memory, exploring the interplay between the spatial arrangement of urban elements, temporality and the experience of the city. Athens is viewed as a city marked by a temporal collage where different historical periods are juxtaposed. This juxtaposition gives Athens the character of a deconstructed city. The city is made present through spatialised remainders, her genius loci. This thesis thus analyses the relationship between Athens past and the present, the strangely familiar and the stereotypically exotic, as interwoven within an urban landscape imagined, gazed and finally, narrated by foreign tourists. The core argument of this work is that the Athenian landscape embodies an urban mythology constructed by the nineteenth century romantic travellers: these, through their writings, fashioned the stereotypical imagery of Athens. Modem tourists are the consumers of these myths. Like their nineteenth century predecessors, tourists stroll around the city following the traces of their memory - key landmarks and symbols, recognising what they have already known; feeling nostalgic for the past -their past, fragmenting the landscape into different historic layers, depopulating it from its present inhabitants, orientalising it. In this work I explore the transmission and reinvention of the myths of Athens through guidebooks, travel brochures, guided tours and tourist photographs. The exploration of the different images of Athens as visualised by tourists leads to a discussion of gendered, orientalised, literary, photographic and cartographic aspects of the Athenian urban landscape. The theoretical framework of the thesis is based on post-modernism, post-structuralism and semiotics. My research methods have been qualitative, including both in-depth interviews and participant observation, following tourists around the city and participating in their activities. I also analysed the ways tourists 'gaze' and photograph the city. My intention is to draw -metaphorically speaking- a mental map including the sites visited, consumed and experienced by tourists

Toxic Gas Sensing on Nanoporous Carbons

Activated carbons, either synthetic, developed in our laboratory, or commercial, were prepared or further modified, in order to introduce specific heteroatoms such as oxygen, nitrogen and sulfur to their matrices. Chips coated with thin layers of the carbon samples were used for the sensing of gaseous ammonia. They were exposed to continuous cycles of various ammonia concentrations (10-500 ppm), and changes in normalized resistance were analyzed. In all cases linear responses were recorded and the chips reached sensitivities as high as 31%, which are comparable to those of modified graphene-based sensors. The applied specific surface chemical modifications were an effective means to control the type of the charge carriers (electrons or holes), and thus the electronic and transport properties. The mechanism of the reversible sensing was governed by several processes including specific interactions between the surface functional groups and the molecules of the target gas, pore-filling with ammonia (especially of pores smaller than 0.7 nm), electron–hole conductivity, and charge transport through ionic conductivity. Strongly acidic carboxylic and sulfonic groups played an important role in ammonia sensing by promoting charge transport via ionic conductivity, due to the formation of NH4+. Among all N-containing groups, nitrogen located in six-membered rings (pyridines and quaternary nitrogen), rather than nitrogen on the periphery (amines, amides) played the most important role in sensing. An important aspect was the conversion of the conduction type from predominantly p- to predominantly n- upon oxidation of the carbon surface due to introduction of electron withdrawing nitro groups to the matrix. Owing to the high porosity of the oxidized carbon and the polarity of the formed -NO2 groups present in the pore system, opposite signal changes compared to the initial counterpart were recorded (decrease instead of increase in the normalized resistance). Interesting changes in the electrical response were noticed for S- and N-dual-doped carbons. Their ability to activate oxygen and generate superoxide ions resulted in oxidation of ammonia to nitrogen dioxide. NO2 adsorbed in the pore system caused an increase in the population of holes (h+) as charge carriers in the matrix, which led to a conductivity increase upon ammonia exposure. The surface chemical and structural features of the carbons acted either synergistically or competitively. When the chips were exposed to H2S, they showed a very low sensitivity to this gas. A high surface acidity of the carbons enhanced their affinity towards NH3 adsorption, contributing to a selective ammonia detection. The role of the specific chemical arrangement of the heteroatoms on ammonia sensing is extensively examined and analyzed