The passage of fluid, ions and macromolecules across the epithelium is controlled primarily by epithelial tight junctions. Altered epithelial permeability is associated with lung disease, and barrier function is impaired by the Th2 cytokine IL-13. This thesis investigates the signalling pathways involved in the modulation of the epithelial barrier by IL-13 stimulation. Initial experiments demonstrated that the human sub-bronchial epithelial cell line Calu-3 could be easily manipulated when grown using an air-liquid culture system. Expression of various key tight junction proteins was demonstrated, as well as a high trans-epithelial resistance (TER) for up to 7 days. Stimulation with IL-13 resulted in a decrease in TER compared with controls and this decrease was shown to be prevented with the PI3K inhibitor ZSTK474. IL-13 did not increase paracellular permeability of the epithelial monolayer to FITC-dextran from the apical to the basolateral chamber and ZSTK474 did not influence FITC-dextran flux. Immunocytochemistry showed that the expression of the tight junction protein claudin 2 was increased by IL-13 stimulation and this change in expression was shown to be PI3K dependent with the PI3K inhibitor ZSKT474 preventing the increase. Further studies were carried out in an attempt to uncover the PI3K isoform responsible for the effects seen on both the TER and the TJ expression. It was shown that inhibition of the p110α isoform with PIK75 mimicked the result observed with the pan-PI3K inhibitor ZSTK474 and prevented the IL-13-induced claudin 2 upregulation. However none of the PI3K isoform inhibitiors showed the prevention of TER, as shown by the pan PI3K inhibitor ZSTK474. The role of STAT6 in TJ modulation was shown to be similar to that of PI3K, in that inhibition of STAT6 had a positive effect on the epithelial barrier by preventing the IL-13-induced TER decrease and the increase in the expression of claudin 2. In addition, both PI3K inhibition and STAT6 inhibition demonstrated effects on basal TER and claudin 2 expression, indicating that both pathways are involved in maintenance of epithelial barrier integrity.

The petroleum industry commonly uses single-layer models to characterize and forecast long-term production in tight gas reservoir systems. However, most tight gas reservoirs are layered systems where the permeability and porosity of each layer can vary significantly, often over several orders of magnitude. In addition, the drainage areas of each of the layers can be substantially different. Due to the complexity of such reservoirs, the analysis of pressure and production history using single-layer analyses techniques provide incorrect estimates of permeability, fracture conductivity, drainage area, and fracture half-length. These erroneous values of reservoir properties also provide the reservoir engineer with misleading values of forecasted gas recovery. The main objectives of this research project are: (1) to demonstrate the typical errors that can occur in reservoir properties when single-layer modeling methods are used to history match production data from typical layered tight gas reservoirs, and (2) to use the single-layer match to demonstrate the error that can occur when forecasting long-term gas production for such complex gas reservoirs. A finite-difference reservoir simulator was used to simulate gas production from various layered tight gas reservoirs. These synthetic production data were analyzed using single-layer models to determine reservoir properties. The estimated reservoir properties obtained from the history matches were then used to forecast ten years of cumulative gas production and to find the accuracy of gas reserves estimated for tight gas reservoirs when a single-layer model is used for the analysis. Based on the results obtained in this work, I conclude that the accuracy in reservoir properties and future gas flow rates in layered tight gas reservoirs when analyzed using a single-layer model is a function of the degree of variability in permeability within the layers and the availability of production data to be analyzed. In cases where there is an idea that the reservoir presents a large variability in ‘’k”, using a multi-layer model to analyze the production data will provide the reservoir engineer with more accurate estimates of long-term production recovery and reservoir properties.

Essentially all producing wells drilled in tight gas sands and shales are stimulated using hydraulic fracture treatments. The development of optimal fracturing procedures, therefore, has a large impact on the long-term economic viability of the wells. The industry has been working on stimulation technology for more than 50 years, yet practices that are currently used may not always be optimum. Using information from the petroleum engineering literature, numerical and analytical simulators, surveys from fracturing experts, and statistical analysis of production data, this research provides guidelines for selection of the appropriate stimulation treatment fluid in most gas shale and tight gas reservoirs. This study takes into account various parameters such as the type of formation, the presence of natural fractures, reservoir properties, economics, and the experience of experts we have surveyed. This work provides a guide to operators concerning the selection of an appropriate type of fracture fluid for a specific set of conditions for a tight gas reservoir.

The petroleum industry commonly uses single-layer models to characterize and forecast long-term production in tight gas reservoir systems. However, most tight gas reservoirs are layered systems where the permeability and porosity of each layer can vary significantly, often over several orders of magnitude. In addition, the drainage areas of each of the layers can be substantially different. Due to the complexity of such reservoirs, the analysis of pressure and production history using single-layer analyses techniques provide incorrect estimates of permeability, fracture conductivity, drainage area, and fracture half-length. These erroneous values of reservoir properties also provide the reservoir engineer with misleading values of forecasted gas recovery. The main objectives of this research project are: (1) to demonstrate the typical errors that can occur in reservoir properties when single-layer modeling methods are used to history match production data from typical layered tight gas reservoirs, and (2) to use the single-layer match to demonstrate the error that can occur when forecasting long-term gas production for such complex gas reservoirs. A finite-difference reservoir simulator was used to simulate gas production from various layered tight gas reservoirs. These synthetic production data were analyzed using single-layer models to determine reservoir properties. The estimated reservoir properties obtained from the history matches were then used to forecast ten years of cumulative gas production and to find the accuracy of gas reserves estimated for tight gas reservoirs when a single-layer model is used for the analysis. Based on the results obtained in this work, I conclude that the accuracy in reservoir properties and future gas flow rates in layered tight gas reservoirs when analyzed using a single-layer model is a function of the degree of variability in permeability within the layers and the availability of production data to be analyzed. In cases where there is an idea that the reservoir presents a large variability in ‘’k”, using a multi-layer model to analyze the production data will provide the reservoir engineer with more accurate estimates of long-term production recovery and reservoir properties.

In petroleum engineering and geophysics, it is often assumed that the rocks are completely rigid bodies with a totally interconnected pore space and that the fluid within the pores does not affect and are independent of the strains in the porous media. These assumptions are often not accurate and also unrealistic because the pore pressure effects are of great importance in all of the geomechanical processes occurring in the subsurface. The hydraulic and mechanical processes are coupled so that the rock deformation causes pore pressure changes and fluid flow (displacement relative to the solid). The time- dependent coupling of the hydraulic and mechanical processes can be described by the theory of poroelasticity. Application of this theory requires the availability of material parameters through experiments. In this work, the main poroelastic parameters are determined for some rock types of interest. The focus of this work is concentrated in low porosity rocks that are commonly encountered. Experimental procedures under drained, undrained and unjacketed conditions were initially completed in Berea Sandstone. Then, Indiana Limestone, Westerly Granite and Welded Tuff specimens were tested in order to obtain Skempton’s pore pressure parameter B, Biot’s coefficient of effective stress α, Bulk Modulus and Grain compressibility. Preliminary results suggest that the parameters B, K and α will change in accordance to the permeability and the porosity of the rock, while K_(S) would depend more on the mineralogy and deposition characteristics of the rock.

Freiberg (Sachsen), Techn. University, Diss., 2004.

Forming and maintaining an intact epidermal permeability barrier (EPB) is necessary to mammalian health and dysregulation of this process can result in serious complications. Tight junctions (TJs) and their integral proteins the Claudins (Cldns) have both structural and signaling importance to the skin barrier and the latter is most likely mediated via Cldn tail interaction with cytoplasmic proteins. Given that the family member Cldn6 is known to be important to EPB function, we set out to determine the contribution of its cytoplasmic tail domain to TJ-mediated homoeostasis. Using transgenic mouse models, we overexpressed epidermal-targeted tail truncation mutants and assessed EPB formation and maintenance. We then used yeast 2-hybrid and quantitative proteomic approaches to identify proteins that interact with this tail region and to assess the downstream effects of overexpressing these proteins in human keratinocytes in culture. We demonstrate that a 10 amino acid region in the cytoplasmic tail is required for efficient epidermal maturation and injury repair and that our mouse models may be applicable to postnatal epidermal maturation and human skin aging studies. We show that in addition to the known interacting partner ZO1, the C-terminal tail of Cldn6 also binds FIZ1 (Flt3 interacting zinc finger protein-1), which we characterize for the first time as a mitogenic factor for keratinocytes. FIZ1 stimulates autocrine pathways involving secreted heparin-binding factors IGFBP3 and DKK1, sensitization to IGF signaling, MAP/ERK activation and increased G1 progression. Specific transcription factors, protein kinases and signaling scaffolds that we identified as novel FIZ1-binding partners likely mediate this signaling. Our studies on the Cldn6 cytoplasmic tail support the importance of this region for epidermal maturation and for maintenance of skin homeostasis throughout life. They also delineate the potential for tail interactors such as ZO1 and FIZ1 to act in concert with Cldns in TJ-based signaling networks to regulate the balance between proliferation and differentiation in keratinocytes. These findings provide new insight into the role of the Cldn6 cytoplasmic tail and will ultimately aid in the development of new diagnostic tools and therapeutic approaches for the treatment of skin conditions rooted in barrier defects.

It has become increasingly apparent that the future of electronic devices can and will rely on the functionality provided by single or few dopant atoms. The most scalable physical system for quantum technologies, i.e. sensing, communication and computation, are spins in crystal lattices. Diamond is an excellent host crystal offering long room temperature spin coherence times and there has been exceptional experimental work done with the nitrogen vacancy center in diamond demonstrating many forms of spin control. Transition metal dopants have additional advantages, large spin-orbit interaction and internal core levels, that are not present in the nitrogen vacancy center. This work explores the implications of the internal degrees of freedom associated with the core d levels using a tight-binding model and the Koster-Slater technique. The core d levels split into two separate symmetry states in tetrahedral bonding environments and result in two levels with different wavefunction spatial extents. For 4d semiconductors, e.g. GaAs, this is reproduced in the tight-binding model by adding a set of d orbitals on the location of the transition metal impurity and modifying the hopping parameters from impurity to its nearest neighbors. This model does not work in the case of 3d semiconductors, e.g. diamond, where there is no physical reason to drastically alter the hopping from 3d dopant to host and the difference in wavefunction extent is not as pronounced. In the case of iron dopants in gallium arsenide the split symmetry levels in the band gap are responsible for a decrease in tunneling current when measured with a scanning tunneling microscope due to interference between two elastic tunneling paths and comparison between wavefunction measurements and tight-binding calculations provides information regarding material parameters. In the case of transition metal dopants in diamond there is less distinction between the symmetry split d levels. When considering pairs of transition metal dopants an important quantity is the exchange interaction between the two, which is a measure of how fast a gate can be operated between the pair and how well entanglement can be created. The exchange interaction between pairs of transition metal dopants has been calculated in diamond for several directions in the (110) plane, and for select transition metal dopants in gallium arsenide. In tetrahedral semiconductors transition metal dopants provide an internal degree of freedom due to the symmetry split d levels and this included functionality makes them special candidates for single spin based quantum technologies as well as physical systems to learn about fundamental physics.

People in the oil and gas industry sometimes do not consider pressure-dependent permeability in reservoir performance calculations. It basically happens due to lack of lab data to determine level of dependency. This thesis attempts to evaluate the error introduced in calculations when a constant permeability is assumed in tight gas reservoir. It is desired to determine how accurate are conventional pressure analysis calculations when the reservoir has a strong pressure-dependent permeability. The analysis considers the error due to effects of permeability and skin factor. Also included is the error associated when calculating Original Gas in Place in the reservoir. The mathematical model considers analytical and numerical solutions of radial and linear flow of gas through porous media. The model includes both the conventional method, which assumes a constant permeability (pressure-independent), and a numerical method that incorporates a pressure-dependent permeability. Analysis focuses on different levels of pressure draw down in a well located in the center of a homogeneous reservoir considering two types of flow field geometries: radial and linear. Two different producing control modes for the producer well are considered: constant rate and constant bottom hole pressure. Methodology consists of simulated tight gas well production with k(p) included. Then, we analyze results as though k(p) effects were ignored and finally, observe errors in determining permeability (k) and skin factor (s). Additionally, we calculate pore volume and OGIP in the reservoir. Analysis demonstrates that incorporation of pressure-dependence of permeability k(p) is critical in order to avoid inference of erroneous values of permeability, skin factor and OGIP from well test analysis of tight gas reservoirs. Estimation of these parameters depends on draw down in the reservoir. The great impact of permeability, skin factor and OGIP calculations are useful in business decisions and profitability for the oil company. Miscalculation of permeability and skin factor can lead to wrong decisions regarding well stimulation, which reduces well profitability. In most cases the OGIP calculated is underestimated. Calculated values are lower than the correct value. It can be taken as an advantage if we consider that additional gas wells and reserves would be incorporated in the exploitation plan.

People in the oil and gas industry sometimes do not consider pressure-dependent permeability in reservoir performance calculations. It basically happens due to lack of lab data to determine level of dependency. This thesis attempts to evaluate the error introduced in calculations when a constant permeability is assumed in tight gas reservoir. It is desired to determine how accurate are conventional pressure analysis calculations when the reservoir has a strong pressure-dependent permeability. The analysis considers the error due to effects of permeability and skin factor. Also included is the error associated when calculating Original Gas in Place in the reservoir. The mathematical model considers analytical and numerical solutions of radial and linear flow of gas through porous media. The model includes both the conventional method, which assumes a constant permeability (pressure-independent), and a numerical method that incorporates a pressure-dependent permeability. Analysis focuses on different levels of pressure draw down in a well located in the center of a homogeneous reservoir considering two types of flow field geometries: radial and linear. Two different producing control modes for the producer well are considered: constant rate and constant bottom hole pressure. Methodology consists of simulated tight gas well production with k(p) included. Then, we analyze results as though k(p) effects were ignored and finally, observe errors in determining permeability (k) and skin factor (s). Additionally, we calculate pore volume and OGIP in the reservoir. Analysis demonstrates that incorporation of pressure-dependence of permeability k(p) is critical in order to avoid inference of erroneous values of permeability, skin factor and OGIP from well test analysis of tight gas reservoirs. Estimation of these parameters depends on draw down in the reservoir. The great impact of permeability, skin factor and OGIP calculations are useful in business decisions and profitability for the oil company. Miscalculation of permeability and skin factor can lead to wrong decisions regarding well stimulation, which reduces well profitability. In most cases the OGIP calculated is underestimated. Calculated values are lower than the correct value. It can be taken as an advantage if we consider that additional gas wells and reserves would be incorporated in the exploitation plan.