Graphene receives enormous attention owing to its distinctive physical and chemical prosperities. Growing and transferring graphene to different substrates have been investigated. The graphene growing on the copper substrate has an advantage of low solubility of carbon on the copper which allow us to grow mostly monolayer graphene. Graphene sheet of few centimeters can be transferred to 300nm silicon oxide and quartz crystal pre-deposited with metal like Cu and Ru. Characterization of the graphene has been done with Raman and contact angle measurement and recently quartz crystal microbalance (QCM) has been employed. The underpotential deposition (UPD) process of Bi on Ru metal surface is studied using electrochemical quartz crystal microbalance (EQCM) and XPS techniques. Both Bi UPD and Bi bulk deposition are clearly observed on Ru in 1mM Bi (NO3)3/0.5M H2SO4. Bi monolayer coverage calculated from mass (MLMass) and from charge (MLCharge) were compared with respect to the potential scanning rates, anions and ambient controls. EQCM results indicate that Bi UPD on Ru is mostly scan rate independent but exhibits interesting difference at the slower scan. Bi UPD monolayer coverage calculated from cathodic frequency change (ΔfCathodic) is significantly smaller than the monolayer coverage derived from integrated charge under the cathodic Bi UPD peak when scan rate is at least 5 mV/s. XPS is utilized to explore the detailed chemical composition of the observed interfacial process of Bi UPD on Ru.

Bootstrapping techniques have the potential to accelerate the development of language technology resources. This is of specific importance in the developing world where language technology resources are scarce and linguistic diversity is high. In this thesis we analyse the pronunciation modelling task within a bootstrapping framework, as a case study in the bootstrapping of language technology resources. We analyse the grapheme-to-phoneme conversion task in the search for a grapheme-to-phoneme conversion algorithm that can be utilised during bootstrapping. We experiment with enhancements to the Dynamically Expanding Context algorithm and develop a new algorithm for grapheme-tophoneme rule extraction (Default & Refine) that utilises the concept of a ‘default phoneme’ to create a cascade of increasingly specialised rules. This algorithm displays a number of attractive properties including rapid learning, language independence, good asymptotic accuracy, robustness to noise, and the production of a compact rule set. In order to have greater flexibility with regard to the various heuristic choices made during rewrite rule extraction, we define a new theoretical framework for analysing instance-based learning of rewrite rule sets. We define the concept of minimal representation graphs, and discuss the utility of these graphs in obtaining the smallest possible rule set describing a given set of discrete training data. We develop an approach for the interactive creation of pronunciation models via bootstrapping, and implement this approach in a system that integrates various of the analysed grapheme-to-phoneme alignment and conversion algorithms. The focus of this work is on combining machine learning and human intervention in such a way as to minimise the amount of human effort required during bootstrapping, and a generic framework for the analysis of this process is defined. Practical tools that support the bootstrapping process are developed and the efficiency of the process is analysed from both a machine learning and a human factors perspective. We find that even linguistically untrained users can use the system to create electronic pronunciation dictionaries accurately, in a fraction of the time the traditional approach requires. We create new dictionaries in a number of languages (isiZulu, Afrikaans and Sepedi) and demonstrate the utility of these dictionaries by incorporating them in speech technology systems. / Thesis (PhD (Electronic Engineering))--University of Pretoria, 2006. / Electrical, Electronic and Computer Engineering / unrestricted

In this dissertation, I present the mechanism of graphene hydrogenation via three different electron sources: scanning electron microscopy, e-beam irradiation and H2 and He plasma irradiation. in each case, hydrogenation occurs due to electron impact fragmentation of adsorbed water vapor from the sample preparation process. in the proposed model, secondary and backscattered electrons generated from incident electron interactions with the underlying silicon substrate are responsible for the dissociation of water vapor. Chemisorbed H species from the dissociation are responsible for converting graphene into hydrogenated graphene, graphane. These results may lead to higher quality graphane films having a larger band gap than currently reported. in addition, the dissertation presents a novel and scalable method of controllably removing single atomic planes from multi-layer graphene using electron irradiation from an intense He plasma under a positive sample bias. As the electronic properties or multi-layer graphene are highly dependent on the number of layers, n, reducing n in certain regions has many benefits. for example, a mask in conjunction with this thinning method could be used for device applications.

This dissertation used letter detection and masked priming to address four questions: Are graphemes or letters more fundamental in low-level reading processes? How does alphabetic-processing knowledge manifest in different languages? Do bilinguals transfer such knowledge across languages? And do young children also show such effects?Some researchers have recently revived an old hypothesis in which graphemes, not letters, are the fundamental, perceptual reading unit. This can be tested by looking at congruency effects in a letter-detection task with masked priming. Six groups participated: Spanish and English monolingual adults; Spanish- and English-dominant bilingual adults; Spanish-dominant bilingual children; and English monolingual children. The experiments with adult monolinguals tested the letter- against the grapheme-as-percept hypothesis. The experiments with developing bilinguals examined whether they would transfer alphabetic-processing knowledge from L1 to L2. And the experiments with English monolingual children probed how early congruency effects with masked primes might occur.Participants responded YES or NO depending on the presence of letters in targets. Both congruent and incongruent masked primes preceded the targets. Among the congruent primes, some contained double vowels, and others single vowels. Assuming letters are fundamental, single- and double-vowel primes in both languages should facilitate and inhibit reactions equally. Assuming graphemes are fundamental, single-vowel primes in English, but not Spanish, should facilitate and inhibit more because double vowels are digraphs in English, and should therefore conceal the identity of their component letters. Bilinguals should show L1-like effects in L2 if they transfer alphabet-specific processing knowledge. Young children should simply show congruency effects if they are able to process letter information automatically.The results with Spanish and English monolinguals suggested that graphemes do exert an effect on the task, but only after letters are perceived. This has major implications for models of proficient reading. The results also suggest that Spanish readers do not construct graphemes from letters, but rather syllables and abstract syllable structure. Bilinguals showed evidence of L1-L2 transfer at low levels of L2 proficiency. This has implications for transitional bilingual education programs. And young children showed congruency effects, which provides another link in establishing the connection between literacy development and proficient reading.

Une décennie après la découverte du graphème par A.K. Geim et K.S. Novoselov ,beaucoup de ses propriétés fondamentales ont été intensément étudiées. En effet, lespromesses du graphème a été etenues et ont conduit a une recherche fructueuse dansdes domaines aussi varies que l'optique, la mécanique, la chimie ou l'électronique. Legraphème mérite ainsi d'être appelée le matériau miracle puisque c'est un très conducteurde la chaleur et de l'électricité, il est l'un des matériau les plus solides tout en étantléger et optiquement transparent. Son succès est en partie dû à la technique de micro clivage,ou exfoliation qui est facile et accessible à tout laboratoire sans équipementlourd. Cela a permis d'étudier les propriétés du graphème avec un large éventail de techniquesexpérimentales. Après l'immense succès du graphème, d'autres matériaux bidimensionnels(2D) ont été obtenus avec la même technique, conduisant à une physiqueparticulièrement riche. / A decade after the discovery of grapheme by A.K. Geim and K.S. Novoselov , manyof its fundamental properties have been intensely studied. Indeed, the early promise ofgrapheme has been kept, leading to a fruitful research in many felds as diverse as optics,mechanics, chemistry or electronics, and grapheme still deserves the name of wondermaterial as among its attributes there is an exceptionally good conduction of heat andelectricity, it is one of the strongest known material while being light and opticallytransparent. Its success was partly due to the easy micromechanical cleavage or scotchtape exfoliation technique accessible to any laboratory without heavy equipment, thatallowed to study the properties of grapheme with a wide range of experimental techniques.Following the success of grapheme, other two-dimensional (2D) materials were obtainedwith the same technique, leading to a particularly rich physics.

The growth of single and multilayer BN films on several substrates was investigated. A typical atomic layer deposition (ALD) process was demonstrated on Si(111) substrate with a growth rate of 1.1 Å/cycle which showed good agreement with the literature value and a near stoichiometric B/N ratio. Boron nitride films were also deposited by ALD on Cu poly crystal and Cu(111) single crystal substrates for the first time, and a growth rate of ~1ML/ALD cycle was obtained with a B/N ratio of ~2. The realization of a h-BN/Cu heterojunction was the first step towards a graphene/h-BN/Cu structure which has potential application in gateable interconnects.

L'acquisition des représentations orthographiques et phonologiques en anglais langue seconde (L2) chez des francophones (élèves en classe de 6ème et de 4ème, étudiants universitaires) était examinée dans ce travail. La technique d'amorçage masqué permettait de révéler la précision du codage orthographique lexical, après seulement deux années d'acquisition de l'anglais, et ce, indépendamment de la typicalité orthographique des mots (étude 1). Des éléments en faveur d'un accès au lexique non-sélectif à la langue étaient observés : un effet inhibiteur des mots cognates émergeait chez des élèves de 4ème dans une tâche de décision lexicale (étude 2). De plus, des expériences mettant en jeu l'effet d'amorçage orthographique inter-langue relevaien de la compétition lexicale inter-langue chez le groupe le plus compétent uniquement (étude 3). Un surprenant effet facilitateur en tâche de décision lexicale pour les mots L2 dont l'orthographe était partagée entre les deux langues, par rapport aux mots dont l'orthographe était spécifique de la L2, signalait l'influence de la typicalité orthographique en reconnaissance visuelle de mots en L2 (étude 4). Le codage graphémique semblait fonctionnel après quelques mois d'acquisition de la L2, bien que des différences émergeaient entre les différents groupes de niveaux au sujet de la typicalité orthographique des graphèmes (étude 5). Enfin, une co-activation des correspondances écrit-oral de chaque langue était mise en évidence chez ces apprenants L2 (étude 6) ainsi que l'influence des correspondances de la L1 sur la reconnaissance de mots en L2 (étude 7) / Orthographic and phonological coding during second language (L2) learning in a school context was examined in the present work. Masked priming techniques revealed that lexical orthographic representations were finely_tuned after only two years of acquisition and that this coding was comparable for words of varying orthographic typically (study 1). Evidence in favour of language non-selectivity during lexical access was uncovered : a cognate inhibition effect emerged in grade 8 for lexical decision (study 2). In addition, tests of cross-language orthographic neighbourhood effects using masked priming revealed cross-language lexical competition in the highest proficiency group only (study 3). Intriguing evidence of facilitation effects in lexical decision for L2 words whose orthography was shared across languages compared to words whose orthography was L2-specific signalled the influence of orthographic typicality during L2 visual word recognition (study 4). Grapheme coding was also shown to be functional after only a few months of L2 learning, though differences emerged across proficiency levels in relation to the orthographic typicality of graphemes (study 5). Finally, evidence was found for the parallel activation of print-to-sound correspondences from both languages in young L2 learners (study 6) and for the influence of first language correspondences on L2 visual word recognition (study 7)

This thesis suggests a new method of developing reading materials for Navajo students. The core of this method is based on phoneme- grapheme relative frequency correspondence data. A short story was phonetically edited and rewritten using the phoneme-grapheme relative frequency method. This short story was one of the major products of the thesis. This short story and three other short stories previously phonically rewritten, were presented in both this form and in original text to 38 Navajo students for reading. Reading speed and reading comprehension were measured for each student on the short stories. The students performed with superior reading speed and with superior reading comprehension on two stories and equal comprehension on two stories. The difference on reading speed was significant at the .01 level. On the two stories with reading comprehension differences, the difference was significant at the .05 level.

Synaesthesia is a fascinating condition in which ordinary stimuli elicit extraordinary sensory experiences. For example, specific tastes may elicit unusual tactile sensations and standard black letters may elicit highly specific colour experiences. These unusual experiences have been shown to have substantial impact on cognition, emotion, perception, and covert attention. Two experiments are presented which show that synaesthesia also influences overt visual attention. In these experiments two grapheme-colour synaesthetes viewed coloured letters while their eye movements were tracked. Letters were presented in colours that were either congruent or incongruent with the synaesthetes' colours. Eye tracking analysis showed that synaesthetes exhibited a colour congruity bias – a propensity to fixate congruently coloured letters more often and for longer durations than incongruently coloured letters – in a naturalistic free viewing task. In a more structured visual search task, this congruity bias caused synaesthetes to rapidly fixate and identify congruently coloured target letters, but led to problems in identifying incongruently coloured target letters. The results are discussed in terms of their implications for perception in synaesthesia.

Synaesthesia is a fascinating condition in which ordinary stimuli elicit extraordinary sensory experiences. For example, specific tastes may elicit unusual tactile sensations and standard black letters may elicit highly specific colour experiences. These unusual experiences have been shown to have substantial impact on cognition, emotion, perception, and covert attention. Two experiments are presented which show that synaesthesia also influences overt visual attention. In these experiments two grapheme-colour synaesthetes viewed coloured letters while their eye movements were tracked. Letters were presented in colours that were either congruent or incongruent with the synaesthetes' colours. Eye tracking analysis showed that synaesthetes exhibited a colour congruity bias – a propensity to fixate congruently coloured letters more often and for longer durations than incongruently coloured letters – in a naturalistic free viewing task. In a more structured visual search task, this congruity bias caused synaesthetes to rapidly fixate and identify congruently coloured target letters, but led to problems in identifying incongruently coloured target letters. The results are discussed in terms of their implications for perception in synaesthesia.