This is Part B of the Thesis. Here is the Link to Part A: http://hdl.handle.net/11375/17844 / <p> This report deals with the effects of various parameters on the resistance and the temperature coefficient of resistance (or the T.C.) of tin dioxide films doped with antimony and boron. The films were produced on cylindrical ceramic substrates by the hydrolysis of SnCl4 and SbCls in the presence of HCl and H3BO3. The T.C. was measured over the range of 25 to 150°C and averaged.</p> <p> Under normal conditions, the films were produced at 950°C with an antimony concentration of 0.457 molar % and a boron concentration of 2.73 molar %. Varying this firing temperature (from 800-1100°C) was found to have no effect on the resistance but increased the T.C. by 2 to 3 ppm/°C per degree change. Varying the antimony content from 0 to about 1 molar % was found to have little effect on resistance. The effect on T.C. was to increase it at lower Sb levels and then to decrease the T.C. as the level increased.</p> <p> Varying the boron content (0 to 4.46 molar %) was also found to have little effect on resistance. A decrease in T.C. with boron content was noted when only the boron was varied, but an increase in T.C. was found when HCl and H2O volumes were varied with the boron. The introduction of additional air into the system was found to have no effect.</p> <p> Film thicknesses were varied by controlling the chemical flowrates. Thinner films were found to have dramatically higher resistances and reduced T.C. values. It was observed that below a certain flowrate resistive failure occurred in the films. It was found in this study that within the statistical distribution of film values, those samples with above average resistance had below average T.C. values and vice-versa. Annealing in vacuum at 500°C was found to produce samples of reduced resistance and increased T.C. while the opposite was found with air annealed samples. Quickly cooled samples were found to be more stable.</p> / Thesis / Master of Engineering (MEngr)

The adhesion of poly(dimethyl siloxane) (PDMS) to silica substrates was measured by 90 degree peel testing of PDMS strips cast on silica substrates. The objective of this work was to investigate the effects of silica surface chemistry on the adhesion between PDMS and silica substrate. Silica substrates with different surface chemistry were prepared by both chemical modification and physical adsorption. Silane coupling agents were used to provide octyl chains and primary amino groups on the silica surfaces. Also silica surfaces were coated with cetyltrimethylammonium bromide (CTAB), polyvinylamine (PVAm) or poly(N-isopropylacrylamide) (PNIPAM) by physical adsorption. The adhesion samples were prepared by casting Sylgard® 184 silicone elastomers on silica surfaces followed by thermal curing. Water contact angle measurements, scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared microscopy (FTIR) were performed to measure the surface properties of the peel test samples. It is believed that hydrogen bonding between siloxane bonds in PDMS and silanol groups on silica substrate contributes to the strong adhesion of PDMS and silica surface. The adhesion forces significantly reduced by the adsorption of PVAm and PNIPAM onto silica surfaces. In addition, the introduction of primary amino groups on silica surface would poison the catalyst during the curing of PDMS, which causes the formation of low crosslinking PDMS in the outer surface and is expected to decline the adhesion force. Lastly, the slightly reduce of adsorbed PVAm (340 kDa) on the silica substrate after peel test is considered to be useful for long-term lubrication. / Thesis / Master of Applied Science (MASc)

First-principles calculations have been carried out to investigate structural and electronic properties of graphene on SiC and diamond substrates and for a study of doping of fluorographene with various surface adsorbates. New insight is given into the problem of the decoupling of the graphene layers from SiC substrates after epitaxial growth. Mechanisms of hydrogen penetration between graphene and SiC(0001) surface, and properties of hydrogen and fluorine intercalated structures have been studied. Energy barriers for diffusion of atomic and molecular hydrogen through the interface graphene layer with no defects and graphene layers containing Stone-Wales defect or two- and four-vacancy clusters have been calculated. It is argued that diffusion of hydrogen towards the SiC surface occurs through the hollow defects in the interface graphene layer. It is further shown that hydrogen easily migrates between the graphene layer and the SiC substrate and passivates the surface Si bonds, thus causing the graphene layer decoupling. According to the band structure calculations the graphene layer decoupled from the SiC(0001) surface by hydrogen intercalation is undoped, while that obtained by the fluorine intercalation is p-type doped. Further, structure and the electronic properties of single and double layer graphene on H-, OH-, and F- passivated (111) diamond surface have been studied. It is shown that graphene only weakly interacts with the underlying substrates and the linear dispersion of graphene pi-bands is preserved. For graphene on the hydrogenated diamond surfaces the charge transfer results in n-type doping of graphene layers and the splitting of conduction and valence bands in bilayer graphene. For the F- and OH-terminated surfaces, charge transfer and doping of graphene do not occur. Finally, the possibility of doping fluorographene by surface adsorbates have been investigated. The structure and electronic properties of fluorographene with adsorbed K, Li, Au atoms, and F4-TCNQ molecule are described. It is shown that adsorption of K or Li atoms results in electron doping of fluorographene, while Au atoms and F4-TCNQ introduce deep levels inside the band gap. The calculated value of the fluorographene work function is extremely high, 7.3 eV, suggesting that p-type doping is difficult to achieve.

The research provided in this thesis focuses on the development of high-gain multilayer millimeter-wave (mm-Wave) antenna structures through additive inkjet printing fabrication processes. This work outlines the printing processes of thick dielectric films for use as printed radio frequency (RF) substrates and provides a proof-of-concept demonstration of the first fully-printed RF structures. Using the outlined processes, demonstrations of high-gain mm-Wave proximity-coupled patch array and Yagi-Uda array antennas are presented, achieving the highest realized gain within the 24.5 GHz ISM band for inkjet-printed antennas in literature.

Current problems on the interaction of complex liquids (i.e. droplets or foams) with complex surfaces (i.e. soft deformable or porous surfaces) are addressed in the following areas: (1) wetting of deformable substrates and surface forces, (2) kinetics of wetting and spreading of non-Newtonian liquids over porous substrates, (3) kinetics of spreading of non-Newtonian solutions over hair, (4) free drainage of foams produced from non-Newtonian solutions, and (5) foam drainage placed on porous substrates. Equilibrium of liquid droplets on deformable substrates was investigated and the effect of disjoining pressure action in the vicinity of the apparent three phase contact line was taken into account. It was proven that the deformation of soft solids is determined by the action of surface forces inside the transition zone. Spreading/imbibition of blood, which is a power law shear thinning non-Newtonian liquid, over a dry porous layer was investigated from both theoretical and experimental points of view. It was found that blood droplet spreading/imbibition over porous substrates shows two different behaviours: (i) partial wetting case with three subsequent stages: initial fast spreading, constant maximum droplet base and the shrinkage of the droplet base; (ii) complete wetting case with only two stages: initial fast spreading and the shrinkage of the droplet base. The wetting of hair tresses by aqueous solutions of two commercially available polymers, AculynTM 22 (A22) and AculynTM 33 (A33) was investigated experimentally. Both A22 and A33 solutions demonstrate well pronounced shear thinning behaviour. Initial contact angle of the A22 and A33 solutions on hair tresses was about 100o. The A22 droplets remained on the hair tress after spreading for at least half an hour. However, a fast penetration of the A33 droplets inside the hair tresses was observed when advancing contact angle in the course of spreading reached a critical value of about 60o. This could be explained by Cassie-Wenzel wetting transition which is caused by filling the pores inside the porous media by liquid. The influence of non-Newtonian rheology of A22 and A33 solutions on foam drainage was also investigated experimentally and a new theory of foam drainage was presented for the case of free drainage. For lowly viscous polymeric solutions and under the assumption of rigid surface of the Plateau border, the predicted values of the time evolution of the foam height and liquid content were in good agreement with the experimental data. However, in the case of highly viscous solutions an interfacial mobility at the surface of the Plateau border has to be taken into account. A completely new theory of foam drainage placed on porous substrate was developed. It was found that there are three different regimes of the process: (i) a rapid imbibition, the imbibition into the porous substrate dominates as compared with the foam drainage; (ii) an intermediate imbibition, that is, the imbibition into the porous substrate and the rate of drainage are comparable; (iii) a slow imbibition, the rate of drainage inside the foam is higher than the imbibition into the porous substrate for a period of time and a free liquid layer is formed over the porous substrate.

No description available.

The Semiconductor Industry Association (SIA) has identified the integration of copper (Cu) with low-dielectric-constant (low-k) materials as a critical goal for future interconnect architectures. A fundamental understanding of the chemical interaction of Cu with various substrates, including diffusion barriers and adhesion promoters, is essential to achieve this goal. The objective of this research is to develop novel organic polymers as Cu/low-k interfacial layers and to investigate popular barrier candidates, such as clean and modified tantalum (Ta) substrates. Carbon-silicon (C-Si) polymeric films have been formed by electron beam bombardment or ultraviolet (UV) radiation of molecularly adsorbed vinyl silane precursors on metal substrates under ultra-high vacuum (UHV) conditions. Temperature programmed desorption (TPD) studies show that polymerization is via the vinyl groups, while Auger electron spectroscopy (AES) results show that the polymerized films have compositions similar to the precursors. Films derived from vinyltrimethyl silane (VTMS) are adherent and stable on Ta substrates until 1100 K. Diffusion of deposited Cu overlayers is not observed below 800 K, with dewetting occurred only above 400 K. Hexafluorobenzene moieties can also be incorporated into the growing film with good thermal stability. Studies on the Ta substrates demonstrate that even sub-monolayer coverages of oxygen or carbide on polycrystalline Ta significantly degrade the strength of Cu/Ta chemical interactions, and affect the kinetics of Cu diffusion into bulk Ta. On clean Ta, monolayer coverages of Cu will de-wet only above 600 K. A partial monolayer of adsorbed oxygen (3L O2 at 300 K) results in a lowering of the de-wetting temperature to 500 K, while saturation oxygen coverage (10 L O2, 300 K) results in de-wetting at 300 K. Carbide formation also lowers the de-wetting temperature to 300 K. Diffusion of Cu into the Ta substrate at 1100 K occurs only after a 5-minute induction period. This induction period increases to 10 min for partially oxidized Ta, 15 min for carbidic Ta and 20 min for fully oxidized Ta.

There are significant differences in the metabolism of nutritional substrates in polytrauma patients. The actual metabolic needs of the patient may not be achieved despite the guidelines and recommendations for energy supply in the parenteral and enteral form of nutrition are followed. Subsequently this may lead to the occurrence of complications. The aim of the study was to compare the energy intake of each nutrient substrate supplied with nutrition by finding the nutritional substrate utilisation value which is obtained from indirect calorimetry measurements in patients with multiple injuries at the surgical ICU 1 of the Hradec Králové Teaching Hospital. By comparing this data you can obtain the optimum value for the nutritional needs of the patients. In the study we used seven spontaneously breathing polytrauma patients, three women and four men, of an average age of 41±21 years. Utilisations of nutritive substrates of each patient were obtained by indirect calorimetry. Accurate information on the amount and composition of nutrition supplied over 24 hours was also obtained. The patients received an average of 3.80±1.40 g/kg/day of carbohydrates, 1.03±0.56 g/kg/day of lipids and 1.40 ± 0.44 g/kg /day of proteins. The total energy intake was on average 30.94±11.03 kcal/kg/day. In six of seven...

>Magister Scientiae - MSc / Microfluidic paper based electrochemical sensing devices (μPEDs) provides a new way for point of care testing (POCT). μPEDs offer an inexpensive, portable, easy to use technology too monitor the environment and diagnose diseases, especially in developing countries in cases where there is not enough infrastructure and a limited trained medical and health professionals. The aim of this work is to develop a paper based electrode which can be further integrated into a microfluidic paper device to develop miniature point of care devices. Paper was used as a substrate for printing of the electrode because it is found everywhere, inexpensive and it is compatible with a number of chemical, biochemical and medical applications. Polyamic acid (PAA) was incorporated into commercial carbon ink and was used to print the working electrode. The first part of the study was conducted using the commercial screen printed carbon electrodes (SPCE) to study and understand the electrochemical behaviour of PAA. Cobalt nanoparticles and cobalt nanoparticles‐polyamic acid composites were electrochemically deposited onto SPCE. The modified electrodes were characterised using cyclic voltammetry. As synthesised polyamic acid were characterised using Scanning Electron Microscopy (SEM) to evaluate the morphology and chemical composition of polyamic acid. Transmission Electron Microscopy (TEM) was used to study the particle size and chemical composition of cobalt nanoparticles. Fourier Transform Infrared Spectroscopy (FTIR) was used to study the chemical nature of polyamic acid and cyclic voltammetry (CV) was used to study the electrochemical behaviour of polyamic acid and cobalt nanoparticle electrodes. The diffusion coefficients and formal potential of the electrodes were calculated. The modified and bare electrodes were also used to electrochemically detect Norfloxacin in an aqueous solution by CV and square wave voltammetry (SWV) and the analytical performance of the electrochemical systems are reported here. The obtained limit of detection for the bare SPCE was 3.7 x 10‐3 M and 14.7 x 10‐3 M for the PAA‐SPCE.

Tanto no meio rural como urbano as novas tendências são de buscar uma melhoria de técnicas e de uso de materiais alternativos buscando-se uma maior sustentabilidade. A utilização de plantas nas paredes e telhados é um dos mais recentes campos da pesquisa ambiental e busca encontrar uma solução ecológica e sustentável para melhorar a qualidade de vida urbana e rural. Uma cobertura verde consiste de um substrato leve e de uma vegetação apropriada, plantada sobre uma base impermeável. Podem conter também camadas adicionais, tais como, um sistema de drenagem e irrigação e uma barreira anti-raízes. Os efeitos positivos da vegetação sobre o ambiente urbano já são bem conhecidos e neste caso da cobertura, diminuem as enxurradas, filtro biológico, redução da poluição do ar, amenizam o calor nas edificações durante o verão e o conservam durante o inverno. Há também benefícios para a fauna, com retorno de espécies que mantêm o equilíbrio biológico local. Essas coberturas podem ter muitas aplicações, como em indústrias, residências, escritórios e outras propriedades comerciais e rurais. Uma criteriosa seleção de plantas permite que a cobertura verde tenha sucesso em condições adversas. Por outro lado, são necessárias pesquisas no sentido de assegurar um meio de cultura que retenha água e ao mesmo tempo proporcione uma boa drenagem para que as raízes não apodreçam, permitindo uma maior gama de espécies de plantas na cobertura. Neste sentido, realizou-se um estudo dos substratos mais abundantes na região, buscando tecnologias apropriadas para a confecção dos telhados verdes e identificando as melhores técnicas de aplicação, de acordo com a necessidade de cada ambiente. Para a realização deste trabalho foram utilizados dez tipos de substratos que foram pré-selecionados de acordo com a disponibilidade no mercado, de mais fácil obtenção e de melhor custo beneficio ambiental. As análises estatísticas utilizam o delineamento experimental inteiramente ao acaso, em esquema fatorial com três repetições e utilizando o programa estatístico SAS para auxiliar na análise e confecção dos gráficos e discussões. Na avaliação do conjunto de características, a turfa marrom (TM) apresentou o menor valor de densidade seca, maior porosidade total, maiores valores de água facilmente disponível, água disponível e capacidade de retenção de água, e mesmo valor de espaço de aeração daquele sugerido como referência sendo um bom material para o uso em telhados verdes, formando compostos com outros materiais e buscando as melhores características e sustentabilidade do sistema. Dentre os substratos comerciais estudados, o substrato para espécies hortícolas (SH) apresentou os maiores valores de capacidade de retenção de água e água disponível para as plantas, possibilitando um maior intervalo entre irrigações ou chuvas, características importantes para o uso em telhados verdes. No entanto, tornam-se necessários mais estudos com a finalidade identificar mais materiais e substratos apropriados para o uso em telhados verdes, levando-se em conta as diferentes características de cada local, tipo de vegetação escolhida, capacidade de suporte da edificação, dentre outro fatores. / Rural and urban new trends seek an improvement in techniques and use of alternative materials for greater sustainability. The use of plants on walls and roofs is one of the newest fields of environmental research, looking for a green and sustainable solution to improve the quality of urban and rural life. A green cover consists of a substrate and appropriate vegetation planted on an impermeable base. It can also contain additional layers, such as a system of drainage and irrigation with an anti-root barrier. The positive effects of roof vegetation on urban environment are well known, as reducing the runoff,acting as a biological filter, reducing air pollution, minimizing heat inside the buildings during summer and maximizing during the winter. There are also benefits to fauna, with the return of various species, maintaining the local biological balance. The coverage can be adapted to industries, homes, offices and other commercial and rural properties. Careful selection of plants allows the green roof to succeed in adverse conditions. In addition, research is necessary to ensure a culture medium that retains water that the same time provides good drainage to prevent root rot, allowing a wider range of plant species in the cover. In this sense, a study was conducted involving the most abundant substrates of our region, seeking appropriate technologies for the manufacture of green roofs and identifying the best application techniques, according to the needs of each environment. For this work ten types of preselected substrates were used according to market availability, easier to obtain and with a better environmental cost/benefit ratio. Statistics of the experimental design was completely randomized in a factorial format with three replications and using the SAS statistical software to assist in the analysis and construction of graphs and discussions. In evaluating the feature of the cover set, brown peat (TM) presented the lowest value of dry density, higher porosity, higher values of easily available water, available water capacity and water retention, and even the amount of aeration space, suggested TM as being a good reference material for use in green roofs. Among the studied commercial substrates, the substrate for horticultural species (SH) showed the highest values of water holding capacity and water available to plants, allowing a longer interval between irrigations or rainfall, an important characteristic for its use on green roofs. However, more studies are needed in order to identify the most suitable materials and for use in green roof substrates, taking into account the different characteristics of each site, vegetation type, bearing capacity of the building, among other factors.