Thesis (M. Sc.)--Carleton University, 2002. / Includes bibliographical references (p. 116-117). Also available in electronic format on the Internet.

Thesis (M.S.)--Ohio University, March, 2009. / Title from PDF t.p. Includes bibliographical references.

Orientador: Marcelo Knobel / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Fisica Gleb Wataghin / Made available in DSpace on 2018-08-04T08:20:32Z (GMT). No. of bitstreams: 1 Duque_JoseGerivaldodosSantos_D.pdf: 2802085 bytes, checksum: 3e11d0645c4b8e47c4e251b671065013 (MD5) Previous issue date: 2005 / Resumo: Não informado / Abstract: Not informed. / Doutorado / Física da Matéria Condensada / Doutor em Ciências

Amorphous materials are used as soft magnetic materials and also as surface coatings to improve the surface properties. Furthermore, the nanocrystalline materials derived from their amorphous precursors show superior soft magnetic properties than amorphous counter parts for transformer core applications. In the present work, laser based processing of amorphous materials will be presented. Conventionally, the nanocrystalline materials are synthesized by furnace heat treatment of amorphous precursors. Fe-based amorphous/nanocrystalline materials due to their low cost and superior magnetic properties are the most widely used soft magnetic materials. However, achieving nanocrystalline microstructure in Fe-Si-B ternary system becomes very difficult owing its rapid growth rate at higher temperatures and sluggish diffusion at low temperature annealing. Hence, nanocrystallization in this system is achieved by using alloying additions (Cu and Nb) in the ternary Fe-Si-B system. Thus, increasing the cost and also resulting in reduction of saturation magnetization. laser processing technique is used to achieve extremely fine nanocrystalline microstructure in Fe-Si-B amorphous precursor. Microstructure-magnetic Property-laser processing co-relationship has been established for Fe-Si-B ternary system using analytical techniques. Laser processing improved the magnetic properties with significant increase in saturation magnetization and near zero coercivity values. Amorphous materials exhibit excellent corrosion resistance by virtue of their atomic structure. Fe-based amorphous materials are economical and due to their ease of processing are of potential interest to synthesize as coatings materials for wear and corrosion resistance applications. Fe-Cr-Mo-Y-C-B amorphous system was used to develop thick coatings on 4130 Steel substrate and the corrosion resistance of the amorphous coatings was improved. It is also shown that the mode of corrosion depends on the laser processing conditions. The microstructure evolution and the corrosion mechanisms operating are evaluated using post processing and post corrosion analysis.

In-situ x-ray photoemission (XPS) and ex-situ FTIR studies of nanoporous organosilicate glass (OSG) films point to the separate roles of radicals vs. VUV photons in the carbon abstraction. The studies indicate that reaction with O2 in presence of VUV photons (~123 nm) result in significant carbon abstraction within the bulk and that the kinetics of this process is diffusion-limited. In contrast, OSG exposed to atomic O (no VUV) results in Si-C bond scission and Si-O bond formation, but this process is self-limiting after formation of ~1 nm thick SiO2 surface layer that inhibits further diffusion. Therefore, the diffusion-dominated kinetics of carbon abstraction observed for OSG exposed to O2 plasma is definitively attributed to the diffusion of O2 down OSG nanopores, reacting at photo-activated sites, rather than to the diffusion of atomic O. Pretreatment of OSG by 900 eV Ar+ ion bombardment also results in formation of 1 nm thick SiO2-like surface overlayer that inhibits O2 diffusion, inhibiting VUV+O2 and O2 plasma-induced reactions, and that the effectiveness of this treatment increases with ion kinetic energy. On the contrary, organosilicate glass (OSG) films with backbone carbon (-Si-R-Si-) exhibit significantly enhanced resistance to carbon loss upon exposure to O2 plasma, radicals and VUV+O2 compared to films with terminal methyl groups (Si-CH3). Films incorporating backbone carbon chains (-Si-R-Si-) were deposited from 1,2 bis (triethoxysilyl) ethane (BTESE) precursor by ebeam or plasma cross-linking. The radical effects on BTESE film indicates negligible carbon loss or Si oxidation, combined with C-O bond formation, under conditions where OSG films with terminal methyl groups exhibit > 80% carbon loss within the surface region of the film. C-O bond formation is never observed for terminal CH3 groups. Further, backbone carbon (-Si-R-Si-) films exposed to VUV+O2 exhibit self-limiting, minimal net carbon loss. This indicates that plasma-induced Si-C bond rupture still occurs in the linking unit, but with a low probability of simultaneous rupture of both Si-C bonds required for abstraction of an in-line methylene bridging group. The data thus demonstrate that OSG films containing backbone carbon groups exhibit greatly reduced rates of carbon loss in the presence of O2 plasma, radicals or VUV+O2 compared to films with terminal carbon groups due to fundamentally different patterns of Si-C bond scission. The results demonstrate the potential of backbone carbon low-k films to resist plasma induced damage.

No description available.

The objective of this dissertation is to develop amorphous metal thin films (AMTFs) for two-terminal electrical device and nanolaminate applications. Two AMTFs, ZrCuAlNi and TiAl, are investigated in both two-terminal electrical device and nanolaminate applications. Material properties including composition, atomic order, surface morphology, surface potential, and electrical resistivity are explored. Application of AMTFs as electrodes in tunneling MIM diodes leverages the ultra-smooth AMTF surface morphology which results from the amorphous atomic order of AMTFs. Analysis methodologies using tunneling MIM diode I-V characteristics are described. A methodology used to estimate potential barrier heights is applied to tunneling MIM diode with differing lower electrode material, upper electrode material and upper electrode deposition technique. A second methodology used to estimate relative tunneling MIM diode insulator thickness is also presented. The presented I-V characteristic analysis methodologies illustrate that tunneling MIM diodes fabricated with AMTF lower electrodes possess tunable I-V characteristics. Nanolaminates are layered materials fabricated with alternating dissimilar thin-film layers. The flexibility of AMTF nanolaminates is illustrated through the presentation of amorphous metal/oxide nanolaminates fabricated with differing AMTFs and aqueous solution deposited oxides. TEM and XPS depth profile analysis of realized nanolaminates are presented. The optical dielectric response of ZrCuAlNi/aluminum phosphate oxide (AlPO) and TiAl/AlPO nanolaminates are evaluated through polarized reflectance measurements and effective medium theory. The optical dielectric response of the nanolaminates differ from the optical dielectric response of the component layers. ZrCuAlNi/AlPO and TiAl/AlPO nanolaminates therefore satisfy the definition of metamaterials. / Graduation date: 2012 / Access restricted to the OSU Community at author's request from May 9, 2012 - May 9, 2013

Thesis (M. Pharmacy ((Pharmaceutics)) -- University of Limpopo, 2022 / According to the biopharmaceutical classification system, Clarithromycin is considered a class II molecule with low solubility. Poorly soluble drugs result in low bioavailability. Various techniques have been studied to improve the solubility of drugs and subsequently bioavailability. Of these techniques, preparation of amorphous form is the preferred method because it is a more effortless and convenient way to improve the aqueous solubility and dissolution of poorly water soluble drugs. The only disadvantage of amorphous materials is that they are less thermodynamically stable and can recrystallize during processing and storage. Aim: The aim of this study is to prepare amorphous form of clarithromycin to improve its solubility, dissolution rate, and, subsequently, bioavailability. Methods: In this study, preparation of amorphous form of clarithromycin was conducted using the quench cooling method in which the purchased anhydrous crystalline clarithromycin was spread on an aluminum foil and heated to a melting point (217˚C - 220˚C) and then rapidly cooled. Various techniques were conducted to characterize the prepared amorphous clarithromycin, and these include Differential Scanning Calorimetry (DSC), Fourier-Transform Infrared Spectroscopy (FTIR), and X-Ray Powder Diffraction (XRPD). In addition, tablets were formulated using the amorphous clarithromycin mixed with selected excipients from compatibility studies, and in vitro dissolution and stability studies were conducted over a period of 6 months. Results: The DSC thermogram results confirmed that the material prepared using the quench cooling process is an amorphous solid-state. Furthermore, the XRPD confirmed an amorphous solid-state with scattering halo peaks. The FTIR also depicted some broader and lower intensity peaks that indicated a formation of an amorphous material. The dissolution rate of amorphous clarithromycin tablets improved by more than 30% when compared to commercial crystalline clarithromycin tablets. The study revealed a drop in dissolution rate at months 3 to 6 under accelerated conditions due to recrystallization. The 6 monthly stability study at long term conditions showed no change in the integrity of the tablets and their contents. Conclusion: As indicated by the study, it can be concluded that the amorphous clarithromycin remained stable during processing and storage under long-term stability for 6 months. Furthermore, based on dissolution results, it can be concluded that amorphous solids have an improved dissolution rate. / Medical Research Council CHIETA

Copper interconnect requires liner materials that function as a diffusion barrier, a seed layer for electroplating, and an adhesion promoting layer. Ruthenium has been considered as a promising liner material, however it has been reported that Ru itself is not an effective Cu diffusion barrier due to its microstructure, which is polycrystalline with columnar grains. The screening study of Ru precursors revealed that all Ru films were polycrystalline with columnar structure, and, due to its strong 3D growth mode, a conformal and ultrathin Ru film was difficult to form, especially on high aspect ratio features. The microstructure of Ru films can be modified by incorporating P. Amorphous Ru(P) films are formed by chemical vapor deposition at 575 K using a single source precursor, cis-RuH₂(P(CH₃)₃)₄, or dual sources, Ru₃(CO)₁₂ and P(CH₃)₃ or P(C6H5)₃ The films contain Ru and P, which are in zero-valent states, and C as an impurity. Phosphorus dominantly affects the film microstructure, and incorporating > 13% P resulted in amorphous Ru(P) films. Metastable Ru(P) remains amorphous after annealing at 675 K for 3 hr, and starts recrystallization at ~775 K. The density of states analysis of the amorphous Ru(P) alloy illustrates metallic character of the films, and hybridization between Ru 4d and P 3p orbitals, which contributes to stabilizing the amorphous structure. Co-dosing P(CH)₃ with Ru₃(CO)₁₂ improves film step coverage, and the most conformal Ru(P) film is obtained with cis-RuH2(P(CH₃)₃)₄; a fully continuous 5 nm Ru(P) film is formed within 1 µm deep, 8:1 aspect ratio trenches. First principles density functional theory calculations illustrate degraded Cu/Ru adhesion by the presence of P at the interface, however, due to the strong Ru-Cu bonds, amorphous Ru(P) forms a stronger interface with Cu than Ta and TaN do. Cu diffusion studies at 575 K suggests improved barrier property of amorphous Ru(P) films over polycrystalline PVD Ru.

O objetivo deste trabalho é analisar a resistência à compressão do concreto e seus possíveis efeitos com o reuso da água e dos resíduos de lavagens dos caminhões betoneiras. A revisão bibliográfica sobre o assunto proposto foi estudado e discutido em países como Grécia, Taiwan, Alemanha, Itália, Cingapura e outros, o que serviu de apoio e reforço para este trabalho. O método para analisar a resistência à compressão foi de comparação entre uma amostra controle (traço padrão de 30 MPa) e amostras com diferentes composições. O resultado de cada amostra foi diferente em função de sua composição, no entanto, pode-se afirmar ganho econômico na ordem de 20,21 R$/m3, além da resistência à compressão ser maior que 90% da amostra controle. As análises realizadas nas amostras através de DRX, MEV e EDS comprovaram que não houve síntese de novos minerais, somente pequenas quantidades (menor do que os limites de detecção do método de DRX) de alumino-silicatos e quartzo dissolvidos que foram sintetizados em novos minerais cristalinos, que podem ser atribuídos como substancias amorfas em estado sol-gel. Com o resultado observa-se que o reuso da água de lavagem dos caminhões betoneiras não interferem na resistência à compressão de novos concretos, assim como o resíduo de lavagem que não apresentou nenhum elemento diferente do composto no cimento, também não interfere na resistência à compressão de novos concretos, desde que haja controle da água presente. / The objective of this study is to analyze the strength of concrete compression and its possible effects on water reuse and waste washes of concrete mixer trucks. The literature review on the proposed subject was studied and discussed in countries like Greece, Taiwan, Germany, Italy, Singapore and others, which served as support and reinforcement for this work. The method for analyzing the compressive strength was compared between the control sample (standard stroke 30 MPa) and samples with different compositions. The result of each sample was different depending on their composition, however, it can be stated economic gain on the order of 20,21 R$/m3, in addition to the compressive strength is greater than 90% of the control sample. The samples were analyzed by DRX, MEV and EDS showed that there was no synthesis of new mineral, only small amounts (lower than the detection limits of the DRX method) dissolved alumino-silicates and quartz which have been synthesized into new mineral crystalline, which can be assigned as amorphous substances in sol-gel state. With this result it was observed that the reuse of the concrete mixer trucks washing water does not interfere with the compressive strength of new concrete, as well as the washing residue which presented no different element of the compound in cement, does not interfere with the compressive strength new concrete, provided that control of the water present.