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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

Study on the Fast-Deposition Low Temperature Hydrogenated Microcrystalline Silicon and Copper Pollution of Thin Film Transistors

Huang, Tz-Shiuan 29 June 2004 (has links)
The improvement and copper contamination of TFTs in active-matrix liquid-crystal displays (AMLCDs) will be discussed in this thesis. TFT with hydrogenated microcrystalline silicon films (mc-Si:H) came to be the attractive candidate due to its higher mobility and stable characteristics. We deposited mc-Si:H films by inductively coupled plasma chemical vapor deposition system (ICPCVD) to achieve fast deposition rate (4~5 Å /sec) which is faster than the conventional PECVD (around 0.1~1 Å/sec). The crystallization of mc-Si:H films deposited by ICPCVD at low temperature was explained by hydrogen etching model. With modulating the hydrogen dilution and rf power of ICPCVD, we can determine the crystallinity of silicon films. Two ways to increase the crystallinity of silicon films was designed: one is the plasma treatment on surface of substrate, and the other is on seed layer. Both methods increased the crystallinity of silicon films and were explained by hydrogen etching and influence of roughness surface. Besides, we discuss the effects of substrate temperature in crystallinity. Microcrystalline silicon films can be deposited at very low temperature as 250¢J, where we may deposit microcrystalline silicon films on flexible plastics substrate in the future. Additionally, we investigated the effects of copper contamination on active layer of TFTs. High resolution large-area AMLCDs will take copper gate and connection to replace aluminum for lowering the RC decay of aluminum connection. We observed that the mobility and output characteristics of TFTs were decreased with copper contamination which played as traps in the channel of TFTs. Besides, part copper contamination at the surface of a-Si layer would form the chemical oxide and eliminate surface state of channel. Therefore, the off current will be decreased.
2

Microcrystalline cellulose-filled engineering thermoplastic composites /

Kiziltas, Alper, January 2009 (has links)
Thesis (M.S.) in Forest Resources--University of Maine, 2009. / Includes vita. Includes bibliographical references (leaves 128-134).
3

Effects of microcrystallinity on physical aging and environmental stress cracking of poly (ethylene terephthalate) (PET) /

Zhou, Hongxia. January 2005 (has links)
Dissertation (Ph.D.)--University of Toledo, 2005. / Typescript. "A dissertation [submitted] as partial fulfillment of the requirements of the Doctor of Philosophy degree in Engineering." Bibliography: leaves 231-241.
4

Vapor sorption studies on microcrystalline cellulose

Kontny, Mark James. January 1983 (has links)
Thesis (M.S.)--University of Wisconsin--Madison, 1983. / Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 120-126).
5

The effects of material characteristics on the compression and properties of dry coated tablets

Thomas, William Iwan January 1998 (has links)
No description available.
6

Extrusion-Spheronization of Talc using Microcrystalline Cellulose as a Pellet Aid: Part I

Jadhav, N., Gade, M., Salunkhe, N., Paradkar, Anant R 12 1900 (has links)
No / The aims of the present work were to pelletize talc by extrusion-spheronization technique using microcrystalline cellulose (MCC) as a pelletization aid and to study its performance as a neutral substrate for coating. A 32 factorial design was used to study the effect of independent variables (X1, amount of talc, and X2, MCC) on pellet properties.
7

Microcrystalline Cellulose-Filled Engineering Thermoplastic Composites

Kiziltas, Alper January 2009 (has links) (PDF)
No description available.
8

Using Agricultural Wastes and Additives to Improve Properties and Lower Manufacturing Costs Associated with Biomass Energy Pellets

Blake, Cody 14 December 2018 (has links)
The objectives of this dissertation’s studies were to determine the effects of different additives on biomass wood pellets’ physical properties and the production energy required to produce each treatment. Chapter II was completed using a pneumatic pelletizer as a small scale test to determine effects of different additives. The pneumatic pelletizer was a good indicator of which additives can be successfully pelletized. The results of this chapter show that using bio-oil can significantly increase calorific value, without significantly decreasing durability and significantly increasing production energy required. Corn starch, in a 4% treatment, was shown to not hinder durability or calorific value significantly, but significantly lower production energy. Biochar was shown to be an additive insignificant in production due to such a low durability. Chapter III is a scaled up pelleting study, which takes additives from Chapter II as well as multiple new additives to determine each one’s effects on the physical properties and production energy effects. The larger scale, Sprout Walden pelletizer gave much different results than that of the pneumatic pelletizer. The results tend to prove beneficial to durability, calorific value, and bulk density with multiple of the treatments. Vegetable oil was a treatment shown to be less beneficial with each increase in additive and would not be recommended in a production setting at such levels. Chapter IV focused on the economic effect of the pellets produced in Chapter III. Equations were made to determine the possible marginal revenue using each of the treatments. The marginal revenue equations take into account the changes in durability and calorific value. Biochar 4%, and vegetable oil at 1% and 2% show that an increase in marginal revenue could be possible with these treatments.
9

Optimisation d'un procédé de dépôt plasma micro-onde pour l'élaboration de substrats de diamant fortement dopés au bore / Optimization of a microwave plasma CVD process for the preparation of highly boron doped diamond substrates

Boussadi, Amine 22 September 2016 (has links)
L’objectif principal de ce travail de thèse a été l’optimisation des conditions de croissance du diamant dans un réacteur MPACVD afin d’une part, obtenir des films de diamant monocristallin à faible densité de dislocations, condition sine qua none pour une utilisation dans le domaine de l’électronique de puissance et, d’autre part, synthétiser des films épais (>100 μm) de diamant monocristallin intrinsèque et fortement dopés au bore sur substrats orientés (111), orientation cristalline connue pour favoriser la formation de macles. Dans une première partie, nous avons développé un procédé d’infléchissement et de confinement desdislocations en utilisant des substrats en forme de pyramide orientés (100) et en déterminant des conditions de croissance bien particulières. Cette étude innovante et originale a permis de lever plusieurs verrous scientifiques et technologiques qui ouvrent la voie à la réalisation de films de diamant monocristallin à faible densité de défauts. Dans une deuxième partie, l’effetdes différents paramètres de croissance a été étudié, afin d’optimiser notre procédé de croissance sur orientation (111). Il a ainsi été mis en évidence l’existence d’une fenêtre de couple pression/puissance micro-onde, température et concentration en méthane qui permettent d’assurer un bon compromis entre qualité cristalline et vitesse de croissance, permettant la synthèse de films épais de diamant fortement dopé au bore sur cette orientation ouvrant ainsi la possibilité de combiner l’efficacité de dopage de type n et la réalisation de composants bipolaires verticaux pour des applications en électronique haute tension-hautetempérature. / The main objective of this PhD thesis is the optimization of diamond growth conditions in a MPACVD reactor in order to one hand, synthesize single crystal diamond films with low dislocation density, prerequisite to their use in the field of power electronics and on the other hand, synthesize thick intrinsic and boron doped monocrystalline diamond films (>100 microns) on (111)-oriented substrates, crystallographic orientation which is well known to promote twinning. In a first part, a process of inflection and confinement of the dislocations has been developed using (100) pyramidal shape substrates coupled with specific growth conditions. This innovative and original study open the way for the fabrication of single crystal diamond films with low defect density. In a second part, the effect of different growth parameters has been studied to optimize our growth process for (111) orientation. It was thus demonstrated the existence of a narrow window of growth parameters pressure, microwavepower, temperature and methane concentration which ensures a good trade-off between crystalline quality and growth rate, allowing the synthesis of heavily boron-doped diamond thick films on this specific orientation, thus opening the possibility of combining the n-type doping efficiency and achieving vertical bipolar components for applications in hightemperaturehigh-voltage electronics.
10

Determinacao das caracteristicas de intumescimento de adjuvantes

Lima Neto, Severino Antonio de January 1996 (has links)
O intumescimento é um dos fatores decisivos que influenciam o comportamento de desintegração de formas farmac6uticas compactadas e, consequentemente, o perfil biofarmacêutico de substancias ativas. Entre os diversos adjuvantes empregados para promover a desagregação daquelas formas farmac6uticas nas suas partículas primarias originais, são utilizadas varias substancias, abrangidas pelo conceito de desintegrantes intumescedores. A escolha do adjuvante mais adequado nestes casos pode ser vista como uma atividade que exige o gasto considerável de tempo e de custos elevados. Além disto deve ser levada em consideração a existência de vários produtos similares no mercado. A questão da equival6ncia representa portanto um desafio importante na fase de formulação. Com o objetivo de aumentar os conhecimentos nesta área, foi desenvolvido equipamento para a avaliação dinâmica do intumescimento de pês. Inicialmente foram considerados fatores de construção do aparelho, tais como a porosidade, espessura e área do filtro de vidro sintetizado. Foram tamb6m avaliadas variações metodológicas, entre as quais a temperatura de realização do teste e o meio liquido empregado. Croscarmelose, um superdesintegrante, foi utilizada como adjuvante-modelo no teste do equipamento. A alteração do meio liquido de ensaio foi o fator que causou a maior influ6ncia sobre os resultados, embora a espessura dos filtros de vidro sintetizado tenha causado alguma alteração quer no tempo como no volume final de intumescimento. intumescimento. Já a mudança de temperatura não provocou diferenças significativas nas observações. Numa segunda fase foi investigada a influência deste desintegrante sobre as características de intumescimento de quatro celuloses microcristalinas (CMCr) isoladas ou adicionadas com um lubrificante. Para tanto elaborou-se um planejamento fatorial 4 X 2 X 2. A presença do desintegrante, como esperado, provocou aumento do volume final de intumescimento das CMCr, que apresentaram, no entanto, comportamentos diferenciados frente ao adjuvante. Já a presença do lubrificante conduziu a resultados totalmente dependentes do tipo de CMCr testada. A análise comparativa entre estes produtos demonstrou que somente num caso houve simitaridade de comportamento. / Swelling is one of the decisive factors influencing the disintegrant behavior of compacted pharmaceutical dosage forms and consequently the biopharmaceutical profile of drug substances. Among the various excipients used to promote the disintegration of such dosage forms in its originally primary particles, several substances, classified as swelling disintegrants, are employed. The choice of the most appropriate excipient in this case can be a time and cost consuming enterprise. Additionally it must be considered that the same substance can be delivered in the market by different producers. The question of equivalence represents also an important challenge in the formulation phase. In order to provide more knowledge in this area an apparatus to analyze the dynamic swelling of powder admixtures was developed. Construction factors such as filter porosity, thickness and area were considered. Methodological variants including essay temperature and liquid medium were also evaluated. Croscarmelose, a superdisintegrant, was used as model excipient to test the self built equipment. The change of the test fluid was the determinant factor on the results, although the thickness of the sintered glass filter showed some influence on both swelling volume and swelling time of this adjuvant. As a second step, the influence of this disintegrant on the swelling behavior of four microcrystalline celluloses (MCC) alone or added with a lubricant were investigated by using a 4 X 2 X 2 factorial design. The presence of the disintegrant was able to increase the swelling volume. Both final swelling volume and time were dependent of the MCC type. The lubricant showed different influences on the four tested MCC. A comparative study demonstrated that only in one case these products presented similarly swelling behavior.

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