Titanium nitride coatings have been widely applied and studied as high temperature diffusion barrier for silicon devices in microelectronics, wear resistant coatings in turbine blade materials, and materials for future high temperature nuclear reactors. In order to enhance the material property, superlattices is one of artificially engineered protective coatings, such as AlN/TiN and TaN/TiN multilayered films. Epitaxial cubic multilayer films, TaN/TiN and AlN/TiN nanolayers were grown on Si(001) by Pulsed Laser Deposition (PLD) with various nanolayer thicknesses and number of interfaces. Microstructural studies include X-ray diffraction (XRD), transmission electron microscopy (TEM), and high resolution TEM with ion-irradiation experiments. Electrical, mechanical and thermal property studies were conducted for the interface and size effects on the nanolayers by using nanoindentation and Transient Thermo-Reflectance (TTR) methods. The microstructural and hardness study on TaN/TiN films with ion irradiation (12 keV and 50 keV He ) suggest no obvious microstructural or mechanical behavior change due to ion irradiation. In addition, titanium nitride that serves as effective diffusion barrier to prevent the inter-diffusion between the nuclear fuel and the cladding material was studied in order to enhance the lifetime of the fuels and the reliability of the fuel claddings. The TiN has good adhesion with the stainless steel and higher hardness than that of bulk TiN on the stainless steel. Thermal conductivity test demonstrates that thin TiN film has compatible thermal conductivity as the MA957 and HT-9 bars. The size effect on electrical resistivity is dominant in both of the epitaxial cubic and the polycrystalline TiN thin films in the thickness ranged from ~60 nm down to ~35nm. In the TaN/TiN multilayer, the grain scattering effect on resistivity is dominant rather than interface influence on the resistivity with comparing epitaxial cubic phase and polycrystalline phase. The microstructure and hardness studies of the AlN/TiN multilayer films with He implantation present that the suppression of amorphization in AlN layers and the reduction of radiation-induced softening were achieved in all nanolayer films. Radiation tolerance was found to be size dependent and the layer thickness leading to the highest radiation tolerance was around 10 nm. In addition, the embedded epitaxial cubic AlN with cladding TiN nanolayers showed higher effective thermal conductivity than that of AlN single layer as well as the embedded polycrystalline AlN in the thickness ranged from 10 nm down to 2 nm. It confirms a suppressed size effect, which reduces the amount of decrease in through-plane thermal conductivity.

Soil-bentonite (SB) slurry walls are one of the most popular techniques for minimizing the horizontal migration of contaminants. Backfill arching, or “hang-up” of the backfilled slurry, on the wall trench has the potential to significantly reduce the effectiveness of these barriers. This research was conducted to supplement the design and installation of an 11,000 m long slurry wall at PotashCorp’s mine in Rocanville, Saskatchewan. The slurry wall is being installed through low permeability glacial till containing permeable granular zones. This study was undertaken to improve the understanding of vertical stress distribution in these deep barriers. In particular, the objective of this study was to develop an understanding of the factors controlling arching and hydraulic conductivity (k) of SB walls. Slurry wall “hang-up” or arching is dependent on shear along the wall of the trench and on a coefficient of lateral earth pressure (K). Consolidated drained (CD) shear box tests were conducted to study the shear strength parameters of the backfill mixes. Six inch proctor mold was modified with load cells on the side walls to measure horizontal stresses along with consolidation. This was used to calculate coefficient of lateral earth pressure, K (which is the ratio of horizontal to vertical effective stress). The results of the laboratory testing program found that K was relatively independent of the percentage of fines present in the SB mix. It also showed that backfill angle of internal friction and k of the backfill decreased with increased fines content. The results of the laboratory testing program were used to model the vertical stress distribution in deep walls. An analytical model (discrete model) and a coupled seepage stress-strain finite element model (FEM) were used to predict vertical stress changes with time and depth for the different backfill materials. The primary conclusion of this research is that slurry wall backfill arching or “hang-up” significantly delays the magnitude and timing of vertical stress build-up in backfill. This loss of vertical stress results in backfill with lower density and higher hydraulic conductivity. The situation was found to be most critical for deep narrow slurry walls. Any advantage in using a coarser graded backfill was offset by higher backfill hydraulic conductivity. The net result is that the upper portions of slurry walls may not be able to achieve their hydraulic conductivity objectives as soon as expected, if at all. In addition, the backfill in the upper portion of the trench may be susceptible to chemical attack and osmotic consolidation. Construction of a 2 m high surcharge berm over the slurry wall was found to increase vertical effective stress and result in significantly lower (2 to 8 times) hydraulic conductivity values in the top 5 metres of the trench. The final hydraulic conductivity (k) at a depth of 5 m was approximately 75 % lower with a surcharge berm. Thus, construction of a surcharge berm over the slurry wall helps to satisfy the k requirement for SB walls and lowers the risk of osmotic consolidation.

No description available.

The synthetic routes to the salts of the 3H-naphtho[1,2-d][1,2,3]dithiazolylium cation and its three selenium containing variants are described. The most efficient approach involves the condensation of bis-acetylated aminoselenolates and aminothiolates with sulfur and selenium halides. Cyclic voltammetry experiments illustrate that the four cations can be reduced to their neutral radical state and are stable in solution. The EPR spectra of all four radicals have been recorded and the spin distributions have been compared with those obtained from DFT calculations. It has been found that the selenium containing radicals are thermally unstable at room temperature, but the all sulfur species has been isolated and characterized by X-ray crystallography. In the solid state, the radicals associate into cofacial dimers and short interdimer S---Sʹ, S---Nʹ and C---Hʹ contacts are observed. The all-selenium species has been characterized in its oxidized state by X-ray crystallography. A series of four challenging crystallographic projects are presented. (1) 8-Phenyl-4-methyl-4H-bis[1,2,3]thiaselenazolo[4,5-b:5ʹ,4ʹ-e]pyridinyl has been prepared and its solid-state structure determined by powder X-ray diffraction methods. The radical crystallizes in the space group P3121 and is isostructural with its ethylated derivative and its all-sulfur containing analogue. Variable-temperature magnetic measurements confirm that the radical is an undimerized S = ½ system with weak intermolecular antiferromagnetic coupling. Pressed pellet variable-temperature electrical conductivity measurements provide a room-temperature conductivity (σRT) of 3.3 ×10-5 S cm-1 and an activation energy (Eact) of 0.29 eV. The results of Extended Hückel Theory (EHT) band structure calculations are presented. (2) Single-crystal and powder X-ray diffraction methods on a family of selenium-containing radicals based the 4-methyl-3H,4H-bis[1,2,3]dithiazolo[4,5-b:5ʹ,4ʹ-e]pyridin-3-yl radical are presented. All three radicals (SSN, SSeN and SeSeN) are isostructural, crystallizing in the space group P212121, and form slipped π-stacks of undimerized radicals with close E---Eʹ contacts. Pressed pellet variable-temperature electrical conductivity measurements of the systems provide σRT = 3 × 10-4 and 1 × 10-3 S cm-1 and Eact of 0.24 eV and 0.17 eV for the SSeN and SeSeN radicals respectively. (3) The crystal structures of 4-methyl-4H-bis[1,2,3]dithiazolo[4,5-b:5ʹ,4ʹ-e]pyrazin-3-yl at 298 K, 123 K and 88 K are presented. At 298 K the radicals remain undimerized, crystallizing in the space group Cmca and forming evenly-spaced π stacks. Upon cooling to 123 K the space group symmetry is lowered by loss of C-centering to Pccn such that the radicals are not evenly spaced within the π-stack. At 88 K a further lowering of space group symmetry to P21/c is observed. (4) [1,3,2]Dithiazolo[4,5-b]pyridin-2-yl is polymorphic, crystallizing in P21 and P21/n. A non-merohedral twin law is required to model the P21 system. The structures of both crystals are comprised of layers of head-to-head π dimers and the two structures differ in the orientation of the π dimers along the stacks. Variable-temperature magnetic data reveal that both phases are essentially diamagnetic at low temperatures and form weak π dimers at higher temperatures. Synthetic methods have been developed to generate the complete series of resonance stabilized heterocyclic thia/selenazyl radicals based on 8-chloro-4-ethyl-4H-bis[1,2,3]dithiazolo[4,5-b:5ʹ,4ʹ-e]pyridin-3-yl. X-ray crystallographic studies confirm that all four radicals are isostructural, belonging to the tetragonal space group P21m. The crystal structures consist of slipped π-stack arrays of undimerized radicals. Variable temperature conductivity measurements reveal an increase in conductivity with increasing selenium content, with σRT reaching a maximum of 3.0 × 10-4 S cm-1 with an Eact of 0.19 eV for the all-selenium containing variant. Variable temperature magnetic susceptibility measurements indicate that all four radicals exhibit S = ½ Curie-Weiss behaviour over the temperature range 20 - 300 K. At lower temperatures, the three selenium-based radicals display magnetic ordering. The first radical with selenium positioned at the E1 site, undergoes a phase transition at 14 K to a weakly spin-canted (φ = 0.010̊) antiferromagnetic state. By contrast, the radical containing the apical selenium and the all-selenium variant, which both possess selenium in the E2 position, order ferromagnetically, with Curie temperatures (Tc) = 12.8 K and 17.0 K respectively and coercive fields Hc at 2 K of 250 Oe and 1370 Oe respectively. The transport properties of the entire series of radicals are discussed in the light of EHT band-structure calculations. A series of bis-thiaselenazolyl radicals (R2BPTSR1) based on the bis-[1,2,3]-thiaselenazolo[4,5-b:5',4'-e]pyridin-3-yl (R1 = Et, Pr and CF3CH2, R2 = Cl; R1 = Et, R2 = Me and Br) have been prepared and characterized by X-ray crystallography. The radicals are formally isostructural, all belonging to the tetragonal space group P21m. The crystal structures consist of slipped π-stack arrays of undimerized radicals packed about centers. Variations in R1 (Et, Pr, CF3CH2) with R2 = Cl lead to significant changes in the degree of slippage of the π-stacks and hence the proximity of the Se---Seʹ contacts. By contrast, variations in R2 (Cl, Br, Me) with R1 = Et induce very little change in either the slippage angle or the Se---Seʹ contacts. Variable temperature conductivity measurements show relatively constant values for σRT (10-5 - 10-4 S cm-1) and Eact (0.27 - 0.31 eV) across the entire series. Variable temperature magnetic susceptibility measurements indicate major differences in the magnetic behaviour. Radicals with R1 = Pr, CH2CF3, R2 = Cl behave as weakly antiferromagnetically coupled Curie-Weiss paramagnets, but radicals with R1 = Et; R2 = Cl, Me, Br demonstrate ferromagnetic ordering, with Tc values of 12.8 K (R2 = Cl), 13.6 K (R2 = Me), and 14.1 K (R2 = Br).

The synthetic routes to the salts of the 3H-naphtho[1,2-d][1,2,3]dithiazolylium cation and its three selenium containing variants are described. The most efficient approach involves the condensation of bis-acetylated aminoselenolates and aminothiolates with sulfur and selenium halides. Cyclic voltammetry experiments illustrate that the four cations can be reduced to their neutral radical state and are stable in solution. The EPR spectra of all four radicals have been recorded and the spin distributions have been compared with those obtained from DFT calculations. It has been found that the selenium containing radicals are thermally unstable at room temperature, but the all sulfur species has been isolated and characterized by X-ray crystallography. In the solid state, the radicals associate into cofacial dimers and short interdimer S---Sʹ, S---Nʹ and C---Hʹ contacts are observed. The all-selenium species has been characterized in its oxidized state by X-ray crystallography. A series of four challenging crystallographic projects are presented. (1) 8-Phenyl-4-methyl-4H-bis[1,2,3]thiaselenazolo[4,5-b:5ʹ,4ʹ-e]pyridinyl has been prepared and its solid-state structure determined by powder X-ray diffraction methods. The radical crystallizes in the space group P3121 and is isostructural with its ethylated derivative and its all-sulfur containing analogue. Variable-temperature magnetic measurements confirm that the radical is an undimerized S = ½ system with weak intermolecular antiferromagnetic coupling. Pressed pellet variable-temperature electrical conductivity measurements provide a room-temperature conductivity (σRT) of 3.3 ×10-5 S cm-1 and an activation energy (Eact) of 0.29 eV. The results of Extended Hückel Theory (EHT) band structure calculations are presented. (2) Single-crystal and powder X-ray diffraction methods on a family of selenium-containing radicals based the 4-methyl-3H,4H-bis[1,2,3]dithiazolo[4,5-b:5ʹ,4ʹ-e]pyridin-3-yl radical are presented. All three radicals (SSN, SSeN and SeSeN) are isostructural, crystallizing in the space group P212121, and form slipped π-stacks of undimerized radicals with close E---Eʹ contacts. Pressed pellet variable-temperature electrical conductivity measurements of the systems provide σRT = 3 × 10-4 and 1 × 10-3 S cm-1 and Eact of 0.24 eV and 0.17 eV for the SSeN and SeSeN radicals respectively. (3) The crystal structures of 4-methyl-4H-bis[1,2,3]dithiazolo[4,5-b:5ʹ,4ʹ-e]pyrazin-3-yl at 298 K, 123 K and 88 K are presented. At 298 K the radicals remain undimerized, crystallizing in the space group Cmca and forming evenly-spaced π stacks. Upon cooling to 123 K the space group symmetry is lowered by loss of C-centering to Pccn such that the radicals are not evenly spaced within the π-stack. At 88 K a further lowering of space group symmetry to P21/c is observed. (4) [1,3,2]Dithiazolo[4,5-b]pyridin-2-yl is polymorphic, crystallizing in P21 and P21/n. A non-merohedral twin law is required to model the P21 system. The structures of both crystals are comprised of layers of head-to-head π dimers and the two structures differ in the orientation of the π dimers along the stacks. Variable-temperature magnetic data reveal that both phases are essentially diamagnetic at low temperatures and form weak π dimers at higher temperatures. Synthetic methods have been developed to generate the complete series of resonance stabilized heterocyclic thia/selenazyl radicals based on 8-chloro-4-ethyl-4H-bis[1,2,3]dithiazolo[4,5-b:5ʹ,4ʹ-e]pyridin-3-yl. X-ray crystallographic studies confirm that all four radicals are isostructural, belonging to the tetragonal space group P21m. The crystal structures consist of slipped π-stack arrays of undimerized radicals. Variable temperature conductivity measurements reveal an increase in conductivity with increasing selenium content, with σRT reaching a maximum of 3.0 × 10-4 S cm-1 with an Eact of 0.19 eV for the all-selenium containing variant. Variable temperature magnetic susceptibility measurements indicate that all four radicals exhibit S = ½ Curie-Weiss behaviour over the temperature range 20 - 300 K. At lower temperatures, the three selenium-based radicals display magnetic ordering. The first radical with selenium positioned at the E1 site, undergoes a phase transition at 14 K to a weakly spin-canted (φ = 0.010̊) antiferromagnetic state. By contrast, the radical containing the apical selenium and the all-selenium variant, which both possess selenium in the E2 position, order ferromagnetically, with Curie temperatures (Tc) = 12.8 K and 17.0 K respectively and coercive fields Hc at 2 K of 250 Oe and 1370 Oe respectively. The transport properties of the entire series of radicals are discussed in the light of EHT band-structure calculations. A series of bis-thiaselenazolyl radicals (R2BPTSR1) based on the bis-[1,2,3]-thiaselenazolo[4,5-b:5',4'-e]pyridin-3-yl (R1 = Et, Pr and CF3CH2, R2 = Cl; R1 = Et, R2 = Me and Br) have been prepared and characterized by X-ray crystallography. The radicals are formally isostructural, all belonging to the tetragonal space group P21m. The crystal structures consist of slipped π-stack arrays of undimerized radicals packed about centers. Variations in R1 (Et, Pr, CF3CH2) with R2 = Cl lead to significant changes in the degree of slippage of the π-stacks and hence the proximity of the Se---Seʹ contacts. By contrast, variations in R2 (Cl, Br, Me) with R1 = Et induce very little change in either the slippage angle or the Se---Seʹ contacts. Variable temperature conductivity measurements show relatively constant values for σRT (10-5 - 10-4 S cm-1) and Eact (0.27 - 0.31 eV) across the entire series. Variable temperature magnetic susceptibility measurements indicate major differences in the magnetic behaviour. Radicals with R1 = Pr, CH2CF3, R2 = Cl behave as weakly antiferromagnetically coupled Curie-Weiss paramagnets, but radicals with R1 = Et; R2 = Cl, Me, Br demonstrate ferromagnetic ordering, with Tc values of 12.8 K (R2 = Cl), 13.6 K (R2 = Me), and 14.1 K (R2 = Br).

Artificial drainage networks established throughout peatlands during the peat extraction process often remain active following abandonment, maintaining a water table relatively far from the surface of the peat and hindering the survival and reestablishment of Sphagnum mosses. Since cutover peatlands are characterized by low (negative) soil water pressures, sufficient internal water storage and balanced water fluxes are critical for the physiological function of spontaneously regenerated Sphagnum mosses. The relative importance of water exchanges between spontaneously regenerated Sphagnum moss cushions and their surroundings are addressed through investigation of the sensitivity of moss moisture dynamics to a range of environmental variables. Precipitation waters are poorly retained within the cushions, which indicated that rain event water can only be relied upon by the mosses for a short period of time. An imbalance between water inputs and losses from moss cushions identified that additional (small) sources of water, such as dewfall and distillation, are potentially important for physiological processes under dry conditions, common in disturbed peatland ecosystems. As an initial restoration effort, rewetting of the peatland by blocking drainage ditches consequently reduced the runoff efficiency and caused the site-average water table to rise by 32 cm. Higher water tables and a blocked drainage network created conditions more favourable for Sphagnum survival through increasing the moisture content and soil-water pressures within the remnant peat deposit. The hydrologic connectivity between moss cushions and the remnant peat was strong when conditions were wet and the water table was within 30 cm of the surface of the cutover peat but weakened as conditions became drier, as reflected by weakened upward hydraulic gradients in the unsaturated zone below the moss cushions. Runoff variability increased following rewetting, and displayed a greater dependence upon antecedent conditions (capacity to retain additional water on-site) and event-based precipitation dynamics. Evapotranspiration rates were 25% higher following rewetting (3.6 mm day-1) compared to pre-restoration ET rates of 2.7 mm day-1. Total storage changes were restricted following rewetting, as a factor of the reduced runoff losses limiting water table drawdown, thereby constraining peat compression and preventing undue drying of the unsaturated zone. Changes to the system hydrology following rewetting of the peatland by blocking drainage ditches created conditions more favourable for Sphagnum survival through increasing the moisture content and soil-water pressures within the remnant peat deposit; although restoration efforts should aim to constrain water table fluctuations to within the upper 30 cm.

No description available.

One of the most critical parameters in the success of a hydraulic fracturing treatment is to have sufficiently high fracture conductivity. Unbroken polymers can cause permeability impairment in the proppant pack and/or in the matrix along the fracture face. The objectives of this research project were to design and set up an experimental apparatus for dynamic fracture conductivity testing and to create a fracture conductivity test workflow standard. This entirely new dynamic fracture conductivity measurement will be used to perform extensive experiments to study fracturing fluid cleanup characteristics and investigate damage resulting from unbroken polymer gel in the proppant pack. The dynamic fracture conductivity experiment comprises two parts: pumping fracturing fluid into the cell and measuring proppant pack conductivity. I carefully designed the hydraulic fracturing laboratory to provide appropriate scaling of the field conditions experimentally. The specifications for each apparatus were carefully considered with flexibility for further studies and the capability of each apparatus was defined. I generated comprehensive experimental procedures for each experiment stage. By following the procedure, the experiment can run smoothly. Most of dry runs and experiments performed with sandstone were successful.

Recently developed models of the acid fracturing process have shown that the differential etching necessary to create lasting fracture conductivity is caused by the heterogeneous distributions of permeability and mineralogy along the fracture faces. To predict the conductivity that can be created by acid in a particular formation, the models require information about these formation properties. This research aims to quantify correlation lengths using a geostatistical description of small scale heterogeneity to ascertain the distribution of permeability and mineralogy in a carbonate formation. The correlation length parameters are a first step in being able to couple acid transport and rock dissolution models at reservoir scale with a model of fracture conductivity based on channels and roughness features caused by small scale heterogeneity. Geostatistical parameters of small scale heterogeneity affecting wells in the Hugoton Field are developed. Data leading to their derivation are obtained from a combination of well logs and cores. The permeability of slabbed core is measured to yield vertical correlation length. Well logs are used to estimate permeability via an empirical relationship between core plug permeability and well log data for calculation of horizontal correlation length. A fracture simulator computes the acid etched fracture width for known treatment conditions. The resulting geostatistical parameters and acid etched width are used to predict acid fracture performance for a well in the Hugoton Field. Application of new model conductivity correlations results in a unique prediction for the acid fracture case study that differs from the industry standard. Improvements in low cost stimulation treatments such as acid fracturing are the key to revitalizing production in mature carbonate reservoirs like the Hugoton Field. Planning and development of new wells in any carbonate formation necessarily must consider acid fracturing as a production stimulation technique. Reliable models that accurately predict acid fracture conductivity can be used to make an informed investment decision.

The focus of this study was to design and build a guarded hot box to test the R-Value of building materials. The Riverside Energy Efficiency Laboratory is looking to expand their testing capabilities by including this service. Eventually, the laboratory will become energy star certified. A guarded hot box facility consists of two boxes maintained at specific temperatures and a guard box around each one that is maintained at the same temperature as the box it surrounds. The ASTM C1363 standard was used as guide for the construction and testing of sample specimen. This standard called for an air velocity profile uniform within 10 percent of the average. Velocity tests were performed with various different configurations to give a uniform velocity. Although the velocity did not meet standards, the configuration chosen included a piece of 1/4" pegboard placed 2" away from the top and the bottom of the inner box. By using the known overall heat added and removed from the system, as well as all the heat losses the heat transferred through the specimen and its R-Value can be calculated. The uncertainty of the R-Value and the accuracy of the testing facility gave conflicting results. Future experiments will use improved testing methods that include differential thermocouples to obtain better uncertainty for the R-Value calculations.