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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.
1

Elaboration par DLI-MOCVD de dépôts nanocomposites TiO2-M (M = Ag, Cu) et propriétés antibactériennes de ces surfaces solides / Elaboration of nanocomposite coatings TiO2-M (M = Ag, Cu) by DLI-MOCVD and antibacterial properties of these solid surfaces

Mungkalasiri, Jitti 05 February 2009 (has links)
La présence de bactéries et biofilms est une préoccupation permanente dans de nombreux domaines. Ils sont à l’origine de nombreux faits d’actualité qui ont un coût important pour le système de santé. L’objectif de notre travail visait à élaborer des films nanocomposite transparents contenant des particules métalliques nanométriques d'élément antibactérien (Ag ou Cu) immergées dans une matrice d’oxyde (TiO<sub>2</sub>). La méthode de dépôt DLI-MOCVD (Direct Liquid Injection-Metal Organic Chemical Vapor Deposition) a été employée pour élaborer les films composites. Ce procédé permet le contrôle de la fraction molaire des précurseurs injectés dans le réacteur CVD et de revêtir des supports 3D (poreux). La croissance et la structure du dioxyde de titane (TiO<sub>2</sub>) sont influencées par la présence du précurseur contenant l’élément antibactérien. La fraction molaire du précurseur (Ag ou Cu) modifie les caractéristiques physico chimiques et structurales des dépôts. L'activité antibactérienne est mesurée selon la norme JIS Z 2801:2000 avec S. aureus et E. coli en l’absence de lumière. Des essais antibactériens spécifiques ont été optimisés afin d'évaluer leur activité proche de condition réelle. La composition des dépôts influence fortement l’activité antibactérienne d’inactif à bactéricide. Des corrélations entre la microstructure et la composition des films et leurs propriétés antibactériennes sont discutées. / The presence of bacteria and biofilms is permanent concern in many fields. Their presences are at the origin of many events which have high costs for the health system. In this objective, this work aimed to elaborate transparent nanocomposite thin films which are composed of nanometric metallic particles of antibacterial element (Ag or Cu) embedded in an oxide matrix (TiO<sub>2</sub>). The DLI-MOCVD process (Direct Liquid Injection-Metal Organic Chemical Vapour Deposition) was used to elaborate these thin films. This process allows the quantity of precursors injected into the CVD reactor to be controlled and porous body to be coated. The growth mechanisms and the structure of the Titanium dioxide (TiO<sub>2</sub>) are influenced by the presence of the organic precursor which contains the antibacterial element. The mole fraction of precursor (Ag or Cu) modifies the physico-chemical and structural properties of films. The antibacterial activity was tested according to the standard JIS Z 2801: 2000 with S. aureus and E. coli without light Specific tests were optimised in order to evaluate their activity in environments more representative. The composition of coatings impacts strongly the antibacterial activities from inactive to bactericidal properties. Correlations between the microstructure and composition of films and their antibacterial properties are discussed.
2

Identifying Barriers to Sustainability of Dual Language Immersion Programs in Utah Schools

Rowley, Jennifer Leigh 31 May 2024 (has links) (PDF)
Dual Language Immersion (DLI) educational programming began in Utah in 2008. Within three short years, DLI programs in Utah schools had grown from 5 to 58 programs statewide. Presently, Utah now has over 301 DLI programs, including instruction in Spanish, Chinese, French, Portuguese, Russian, and German. DLI programs have many benefits and have attracted many student families. However, not much research has been done on program planning, implementation, and the sustainability of DLI programs within individual school cultures and climates. This study will examine the satisfaction level of faculty, staff, administrators, and parents at DLI schools (including how supported/understood each of these groups feels if issues arise), how the presence of a DLI program affects a school (e.g. culture, special needs, relationships), and if there are any barriers to sustainability of DLI programs in Utah schools. A survey of perceptions among parents and educators, including administrators, was offered state-wide. Quantitative results were analyzed in aggregate and analyzed according to descriptive statistics. Results were used to inform a better framework for program planning, implementation, and sustainability of DLI programs in Utah schools.
3

Attitudes, Opinions, and Beliefs of Teachers Toward Dual Immersion Programs in Utah Schools

Hawks, Amy Lynn 30 May 2024 (has links) (PDF)
Dual language immersion programs have been on the rise in the United States as a proven effective form of bilingual education. As of the 2018–2019 academic year, Utah had 224 dual language immersion (DLI) programs; 113 Spanish, 65 Chinese, 30 French, 13 Portuguese, 2 German and 1 Russian. Roughly 34,000 students were enrolled in one of these programs. The DLI programs in Utah use a 50:50 model, which means half of the students' day is in the partner language model and half is in English. The purpose of my study was to research teachers’ attitudes, opinions, and beliefs within a DLI school environment and understand their experiences of the benefits and challenges on how the DLI program has impacted their career. In order to gain a better understanding of the DLI program and all that it entails regarding teacher attitudes, opinions, and beliefs, a qualitative study, using interpretative phenomenological analysis (IPA), was conducted. There were 12 participants, three of which were male and nine of which were female. They taught in DLI schools in Spanish, English, German, and Chinese. Findings from the interviews conducted identified six primary themes and seven secondary themes from teachers’ experiences working in a DLI program. The primary themes included cultural awareness, school environment, support, curriculum development, collaboration and training. Teachers wanted more training in order to be more prepared to teach dual immersion. They also needed materials and resources that are readily available to them for the target language being taught so they aren’t wasting their time and money creating resources that should be provided. Teachers felt that collaboration is a struggle because of the different schedules that the dual immersion programs require. These finding are based on how educators experienced the DLI program in their respective schools. Implications and recommendations for implementation of a successful dual immersion program are discussed.
4

Films nanométriques poreux élaborés par DLI-CVD comme catalyseurs de mu-PEMFC : une alternative au tout platine ? / Porous thin films obtained by DLI-CVD as mu-PEMFC catalysts to replace platinum

Zanfoni, Nicolas 16 November 2016 (has links)
Ce travail porte sur le développement de protocoles de croissance par CVD à injection directe de liquide (DLI-CVD) de films catalytiques poreux potentiellement utilisables dans les piles à combustible de type PEMFC. Les objectifs étaient de contrôler et de réduire au maximum la charge en platine, d’obtenir des matériaux à grande surface spécifique, c'est-à-dire très poreux, mais aussi d’utiliser des précurseurs à bas coût.Dans un premier temps, le platine a été promu par de l’oxyde de cérium, matériau qui possède lui-même des propriétés catalytiques. L’optimisation des paramètres de croissance a montré le rôle majeur de la température de dépôt mais aussi du flux des précurseurs sur la morphologie finale des films. Un dopage contrôlé en platine de la surface de l’oxyde de cérium a ainsi pu être mis au point à partir du dépôt simultané de cérine et de platine. Le flux de précurseur du platine a alors permis d’ajuster la charge et l’état d’oxydation de cet élément au sein des films sans pour autant modifier leur porosité. Il est, par exemple, possible d’élaborer des films minces d’oxyde de cérium composés de particules nanométriques dopées en extrême surface avec 5 % de platine à l’état +II. L’effet du flux de précurseur sur l’état d’oxydation du platine a été confirmé pour le système Pt/TiO2. Dans un second temps, des oxycarbures de tungstène ont été synthétisés de façon à éliminer totalement le platine du catalyseur. Un procédé en deux étapes a été mis au point permettant d’obtenir des dépôts d’oxycarbure de tungstène possédant de grandes surfaces spécifiques en déposant un film utra-mince et conforme d’oxycarbure sur une couche poreuse d’oxyde de tungstène. / This work is focused on development of growth protocols by direct liquid injection chemical vapor deposition (DLI-CVD) of catalytic porous films which could be used in proton exchange membrane fuel cells (PEMFC). The aim of this work was to reduce or even proscribe platinum in catalysts having large specific surface area i.e. being very porous. Besides, the aim is also to use mainly low cost precursors.Cerium oxide, which is a material widely used as catalyst, has been chosen to partially substitute platinum. Porous CeO2 layers were obtained by the optimization of processing parameters such as deposition temperature or precursors flow rates. Controlled platinum doping of cerium oxide surface has been obtained from deposition of ceria and platinum at the same time. The platinum precursor flow rate has allowed adjusting the load and the oxidation state of Pt in films without changing their porosity. For example, it was possible to synthesize thin cerium oxide films composed of surface Pt doped nanoparticles. In such a case, the Pt content is 5% in top most layers and its oxidation state is +II. The effect of precursor flow rate on the platinum oxidation state was confirmed from the study of the Pt / TiO2 system. Finally, platinum has been fully replaced by tungsten oxycarbide. A two steps process has been developed to obtain porous oxycarbide layers by depositing a conformed tungsten oxycarbide ultra-thin film on a porous tungsten oxide layer.
5

Growth and Development of Greenhouse Vegetable Seedlings Under Supplemental LED Lighting

Hernández, Ricardo January 2013 (has links)
The greenhouse industry is interested in light emitting diodes (LEDs) as a light source supplement to solar light to improve plant growth and development. Before LEDs can be adopted as supplemental light for greenhouse crops, plant responses to LED spectral quality need to be investigated. Tomato and cucumber seedlings were grown under different supplemental blue and red photon flux ratios (B:R ratios) under high (16-19 mol m⁻² d⁻¹) and low (5-9 mol m⁻² d⁻¹) solar daily light integrals (DLIs). The supplemental daily light integral was 3.6 mol m⁻² d⁻¹. A treatment without supplemental light served as a control. Both tomato and cucumber seedlings had increased growth rate and improved morphology when grown under the supplemental LED light compared to the control. However, no significant differences were observed for any growth and morphological parameters measured in this study between the different B:R ratios for both cucumber and tomato transplants under high DLI conditions. Cucumber seedlings showed a tendency to decrease dry mass, leaf number and leaf area under low DLI conditions with increasing B:R ratio. Tomato seedlings did not show any differences between the different B:R ratios under low DLI conditions. Seedlings growth and morphology under supplemental LED light were compared to those under supplemental high pressure sodium (HPS) light. Cucumber seedlings under supplemental HPS light had greater shoot dry mass than those under the supplemental red LED light. Tomato shoot dry mass showed no differences between the HPS and red LED supplemental light treatments. Cucumber seedlings were also grown under supplemental LED pulsed lighting and supplemental LED continuous lighting. Cucumber seedlings showed no differences in shoot dry mass and net photosynthetic rate between the treatments. Collectively, these studies concluded that red LED is preferred for supplemental lighting and the increase of blue light does not offer any benefits unless the efficiency of blue LEDs largely exceeds the red LEDs. The results of this research can be used for fixture development by LED manufactures and as a decision making tool for the adoption of supplemental LED lighting by greenhouse growers.
6

Time-Dependent Microclimate Effects on Yield and Anthocyanin Levels of Lettuce (<i>L. sativa</i>) and Choi (<i>B. rapa</i> var. <i>chinensis</i>)

Walden, Susan January 2017 (has links)
No description available.
7

DÉPÔT DE CARBURES, NITRURES ET MULTICOUCHES NANOSTRUCTURÉES Á BASE DE CHROME SOUS PRESSION ATMOSPHÉRIQUE PAR DLI-MOCVD NOUVEAUX PROCÉDÉS ET POTENTIALITÉS DE CES REVÊTEMENTS MÉTALLURGIQUES

Douard, Aurélia 11 July 2006 (has links) (PDF)
Des procédés atmosphériques de dépôt chimique en phase vapeur assisté par l'injection directe liquide (DLI-CVD), prometteurs pour traiter des pièces métalliques au défilé, ont permis l'élaboration à basse température de revêtements métallurgiques performants. Deux précurseurs organométalliques de chrome ont été employés dans différentes atmosphères : Cr (CO)6 pour des dépôts issus du système chimique Cr-O-N-C, et le bisbenzènechrome pour des monocouches de chrome métallique, de carbure (Cr-C) et de nitrure de chrome (CrN), ainsi que des multicouches CrN/Cr-C de bipériode 25 nm. Une approche thermodynamique a permis le calcul d'un nouveau diagramme ternaire Cr-N-C à 527°C, et l'étude de l'impact du solvant sur la nature et la qualité des dépôts en comparaison avec les systèmes chimiques sans solvant. Les propriétés des revêtements (dureté, adhérence, usure, corrosion) sont discutées en relation avec leur microstructure. Les revêtements multicouches nanostructurés CrN/Cr-C présentent des duretés et une tenue à l'usure prometteuses.
8

Mikroprocesorový modul řízení předstihu zapalování dvoutaktního motoru / Two-stroke Engine Pre-ignition Controller with Microcontroller

Veselý, Tomáš January 2010 (has links)
This paper deals with the problem of two-stroke engine pre-ignition controller with the use of microcontroller for single-cylinder engine and double-cylinder engine. The mechanical design is drawn for motorcycles JAWA and ČZ and for engines of the same mechanical type. The establishment uses non-contact status analysis of engine with non-electric sensor. The very important thing for the design is the simplicity of the establishment. The other important thing is the minimisation of mechanical arrangement of engine and the vehicle as a whole. The importance of this establishment is non-contact switching and the possibility of changing pre-ignition maps depending on the number of rotations per minute, the temperature and the load of the engine.
9

Reading Fluency Development and Science in a Fourth Grade Dual Language Immersion Classroom

Casares, Talia A. 11 April 2022 (has links)
Students from dual language immersion (DLI) classrooms are required to learn the language through content. However, some students have not yet developed these abilities by the time they start fourth grade. Thus, to fully comprehend content such as science, students need stronger reading and writing abilities in the second language (L2). To help stakeholders have a better understanding on how to effectively help students throughout this process, this action research studied the effectiveness of integrating literacy with science and mobile assisted language learning (MALL). Findings showed that the integrations of literacy, science and MALL were effective with statistically significant results in science and reading. These findings also yielded pedagogical implications about the importance of considering students' language background and gender, as well as the use of MALL when teaching and planning the curriculum for DLI classrooms.
10

Synthesis of Functional Multilayer Coatings by Plasma Enhanced Chemical Vapor Deposition

Xiao, Zhigang 02 July 2004 (has links)
No description available.

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