No description available.

No description available.

No description available.

No description available.

The ZEBRA battery based on Na/NiCb chemistry shows promise for powering electric vehicles and load leveling systems. The ZEBRA cell consists of a liquid sodium negative electrode separated from the positive electrode by a W'-alumina solid electrolyte. The current state of development of this battery makes use of glass sealing and thermo compression sealing as an integral part of the cell assembly. One objective of the present research was to reduce the thickness of the W'alumina electrolyte thickness as a means to improve perfomance, by lowering the internal cell resistance. The second objective was to develop a ceramic seal with matching thermal expansion coefficient (TEC) to increase battery durability. An added benefit realized with the new ceramic seal was its use for high temperature applications such as emf measurements ordinary systems to determine thermodynamic properties. Dense electrolyte tubes with reduced thickness of less than 100 J..Lm and supported on a porous substrate were successfully produced by slip casting. The slip casting parameters, sintering conditions and materials were optimized and electrolyte resistance was measured by a DC method. A ceramic seal was developed from a eutectic mixture of Na20 and Al203 and tested in galvanic cells. The reproducibility of the emf data shows that the seal is fully impervious and can sustain a high alkali pressure atmosphere up to 1 000°C without cracking or degradation. The seal microstructure revealed liquid phase formation of the seal and diffusion bonding with the lid and tube. The thermodynamic properties and phase relations of the Na-Si binary system were studied by the emf method using Na|β-alumina|Si-Na galvanic cells over the whole composition range below 600°C. There is very limited solubility of Si in molten Na. Properties of the sodium silicon compounds were determined from the emf measurements. / Thesis / Doctor of Philosophy (PhD)

<p> Powder Metallurgy (P/M) offers a very efficient method to produce high volume, high throughput steel parts. The two most important property issues affecting P/M steels are: (I) possessing high mechanical properties despite having inherent internal porosity; (2) maintaining very tight dimensional tolerances during processing (sintering). Researchers are continually looking at ways to improve these two properties while keeping costs down. As in wrought and cast steels, in most applications P/M steels are alloyed; in P/M processing, alloys are typically added to Fe + C powder mixes as elemental powders. The entire mix of Fe+ C +elemental alloying additives are then consolidated under high pressure and sintered at high temperatures to strengthen the compact. The current work deals mainly with the the most commonly used alloying additives in P/M steels, Ni and Cu. </p> <p> While it is well-known that Ni and Cu do indeed improve the mechanical performance of steels and do affect the dimensional change of P/M parts in specific ways, for over 50 years the same standard Ni and Cu powders have been used in the industry. With new breakthroughs in the production of extra-fine metal powders (- 1-2 urn) P/M researchers now must examine the effect of particle size of alloying additions on the performance of sintered steels. Prior to the current work, significant documented work investigating the effect of particle size of Ni and Cu on the performance of P/M steels was very limited. </p> <p> The current work examined: (I) Ni powder particle size effects in P/M Ni steels; (2) Ni powder particle size effects in P/M Ni-Cu steels; (3) Ni and Cu powder particle size effects in P/M Ni-Cu-Mo steels. </p> <p> Specific focus was on determining the effects of particle sizes on the dimensional control and mechanical peformance of P/M steels. With both Ni and Cu, the finer the powder addition the better the dimensional control and mechanical performance of the steels. In steels containing both Ni and Cu, finer Ni also improved the distribution and diffusion of Cu. This suggested that there was a significant interaction between Ni and Cu during sintering which could be tailored to improve properties. The effect of changing Ni particle size on overall steel properties was significantly greater than the effect of changing Cu particle size. </p> <p> Mechanistic analyses via optical microscopy, SEM-EDX and E-SEM investigation, dilatometry, and differential thermal analysis were carried out to explain the results. Mathematical models were also developed to show the effect of Ni and Cu particle size on diffusion into the Fe matrix during sintering. </p> / Thesis / Master of Applied Science (MASc)

The effect on Ni^2+ uptake of human serum albumin (HSA), sodium diethyldithiocarbamate (DOC), D-penicillamine (O-Pen) , ethylenediaminetetra-acetic acid [di sodiurn salt] (EDTA) , L-aspartic acid (L-Asp) , L-Lysine (L-Lys) , and L-histidine (L-His) was examined in three cell lines: (1) human red blood cells (RBCs), (2) cultured human B-lymphoblasts and (3) rabbit alveolar macrophages. It was found that EDTA, L-His, HSA, and O-Pen were good inhibitors of ^63Ni^2+ uptake by cells and each was able to remove ^63Ni^2+ previously associated with the cells. In contrast L-Lys and L-Asp, which do not bind Ni^2+ well, were both poor inhibitors of Ni uptake and poor sequestering agents for cell-associated Ni^2 +. Thus it seems that at physiological concentrations , L-His and HSA play a major role in regulating the association of Ni^2+ with cells. DOC enhanced cellular uptake of ^63Ni^2+, but was not very effective in removing ^63Ni^2+ from cells. An increase in pH enhanced ^63Ni^2+ uptake in the lymphoblasts, macrophages and human peripheral lymphocytes. This dependence was interpreted to indicate the existence of either: (1) an increase in membrane permeability with an increase in pH; (2) the development of a proton gradient across the cell membrane favouring the antiport transport of H^+ and Ni^2+; or (3) Ni^2+;proton competition for cellular binding groups. The cellular uptake of Ni^2+ is interpreted in terms of an "equilbrium" model of metal-ion transport. It is concluded that since HSA and L-His can control cellular uptake and removal of Ni^2+, they may play a role in regulating the cellular toxicity of this ion. It was found that L-His and O-Pen acted similarly such that at various concentrations both inhibited cellular uptake of ^63Ni^2+ but did not change the normal distribution of Ni^2+ within the cell. Conversely, DOC enhanced Ni^2+ uptake by cells while simultaneously shifting the distribution of Ni^2+ from the cell lysate to the cellular membranous pellet. Furthermore, DOC caused Ni^2+ to become more lipophilic as shown by the increase of ^63Ni^2+ in a chloroform extract. DOC also caused a change in Ni^2+ distribution in whole blood by enhancing Ni^2+ association with RBCs and lymphocytes and decreasing serum-associated Ni^2+. The different responses produced by O-Pen, L-His and DOC are ascribed to the hydrophilicity of the [Ni(D-Pen)_2]^2- and Ni(His)_2 complexes and the lipophilicity of the Ni(DDC)_2 complex, and allow a rationalization of the contrasting therapeutic effects of O-Pen and DDC. / Thesis / Master of Science (MS)

I have submitted another pdf file which is my permissions for figures used in my thesis. The name this file is Clearance. / Nickel Hydroxide is one of highly active materials used in various energy conversion applications. One of the key factors in the deposition of Ni(OH)2 is the active surface area which plays an important role in improving the efficiency of transformation reactions. There are various methods to enhance the active area. One method that can be used to modify the morphology of deposited Ni(OH)2 is to generate porous structures. Ni(OH)2 can be formed in two different phases namely alpha and beta. The main objective in our work is to optimize the synthesis conditions and characterize structures at the nanoscale, and also demonstrate unequivocally the presence of alpha and beta phases. For this work, a combination of electron microscopy and electrochemistry is needed to modify the morphology of nickel hydroxide and for detailed structural characterization. Various characterization techniques are used to investigate different electrochemical depositions conditions of Ni(OH)2 in alpha and beta phase forms using Direct and Indirect methods, respectively. Kinetically, alpha-Ni(OH)2 is easier and faster to be synthesized and can be deposited directly in one step. During cyclic voltammetry of alpha-Ni(OH)2 in KOH, the volume of material involved in the oxidation reaction increases in every cycle. Scanning Electron Microscopy and Transmission Electron Microscopy characterization shows that this may be due to microbubble formation that transform deposited sheets to particulate shapes. On the other hand, conversion of nickel metal to beta-Ni(OH)2 during cyclic voltammetry causes an expansion of particles. Effectively, nickel hydroxide is formed on the shell while nickel remains in the core. High Resolution Transmission Electron Microscopy is then used to identify the distribution of these phases. Another foremost feature for the beta phase is to make nickel metal in any desired shape, which can then be converted to beta-Ni(OH)2 through Cyclic Voltammetry in KOH. The presence of both phases is demonstrated with electron diffraction. Finally, as future work, all experiments will be performed in-situ TEM using liquid cell to observe structural changes in real time. / Thesis / Master of Science (MSc)

No description available.

No description available.