Carbon capture and storage technologies are required in order to reduce greenhouse gas emissions, while continuing to utilize existing fossil-fueled power generation stations. Of the many developing post-combustion CO2 capture technologies, calcium looping appears promising due to its high thermal efficiency, technical feasibility at commercial-scale, and low sorbent cost. Calcium looping has now been performed at the larger-scale, but there is still a significant quantity of information about sorbent performance, the fate of trace pollutant emissions (specifically SO2 and HCl), dual fluidized bed operating configurations, and impact of realistic operating conditions that still needs to be determined. Based on an economic analysis of the process, three key parameters serve to have the largest potential economic impact: (1) the sorbent deactivation rate, (2) the Ca/C molar ratio, and (3) the rate of sorbent attrition. Therefore, a series of bench-scale, pilot-scale, and continuous pilot-scale testing were conducted to not only explore these parameters from an improvement standpoint, but accurately determine them under conditions expected at the commercial-scale. The presence of HCl did not have a significant impact on sorbent performance provided that steam is present during calcination, although issues with downstream corrosion could be a factor. High CO2 partial pressures during calcination, coupled with high temperatures and the presence of SO2, resulted in dramatically lower cyclic carbonation conversions and a reduced high CO2 capture efficiency regime. Continuous pilot-scale testing generated realistic, and more detrimental, values for sorbent carrying capacity, Ca/C molar ratio, sorbent make-up rates, and rate of sorbent elutriation, that can now be utilized for techno-economic evaluations and scale-up of the technology.

Human red blood cell ghosts were prepared by a modification of the procedure of stepwise hemolysis (57). EDTA (1.0 mM) was included in the washing procedure to remove endogenous ATP and divalent cations. Ghosts resealed with appropriate amounts of ATP, calcium and magnesium were found to have Mg+Ca-ATPase activity and linearity was maintained up to thirty minutes. Active calcium transport could be studied in these ghosts by measuring the change ln the cellular concentration of calcium over time by atomic absorption spectrophotometry. Variation in the concentration of calcium in the loading medium resulted in an activation of Mg+Ca-ATPase and two peaks were evident on the activation curve. The high and low affinity Mg+Ca-ATPase were maximally stimulated at 0.25 and 5.0 mM calcium in the loading medium,respectively. The velocity of calcium transport was also found to be dependent on the concentration of calcium in the loading medium and was activated over the concentration range of 0.1 to 5.0 mM calcium. A change in the concentration of cellular calcium was not evident in the absence of added ATP. In contrast to the activation of Mg+Ca-ATPase two peaks were not obtained, and the activation curve had a sigmoidal appearance. Comparison of the calcium activation curves of Mg+Ca-ATPase and calcium transport revealed, a similarity in the shape and position of the low affinity part of the Kg+Ca-ATPase and calcium transport activation curves. A stoichiometry of two (Ca :ATP) was obtained, in the low affinity activity range. Ruthenium red (0.05 to 0.4 mM) selectively inhibited the low affinity Mg+Ca-ATPase and inhibited calcium transport over the same concentration range to a similar degree. Both low affinity Mg+Ca-ATPase and calcium transport were inhibited by external ruthenium red with an I₅₀ of 0.2 mM. Propranolol, qulnidine and quinine (10⁻⁵ to 10⁻³M) were found to be Ineffective in stimulating or Inhibiting Mg+Ca-ATPase when added to the Internal and external aspects of the ghosts. Manganese, added to the loading medium over a wide concentration range, was unable to substitute for calcium in activating Mg+Ca-ATPase. External divalent cations calcium and magnesium further increased Mg+Ca-ATPase activities when added to the external medium. Maximal stimulation occurred at a concentration of approximately 3.0 mM and calcium was almost twice as effective as magnesium. / Pharmaceutical Sciences, Faculty of / Graduate

Ionomycin is a stereochemically complex calcium ionophore. An analogue (34) of ionomycin has been designed and its synthesis initiated. Regions of the analogue which parallel portions of ionomycin do not incorporate any of the chiral centers found in the natural product. The analogue 34 also incorporates a highly conserved tripeptide found in the calcium binding site of troponin C proteins. [ Formula omitted ] / Science, Faculty of / Chemistry, Department of / Graduate

Super-elastic scattering measurements were taken from calcium using the spectrometer described in this thesis. Calcium atoms were excited from the 41S0 ground state to the 41P1 excited state using a high resolution continuous wave laser set to a wavelength of 423 nm. A beam of electrons with a well defined energy was directed at the laser excited calcium atoms. The excited state was then described by a set of atomic collision parameters P_lin, gamma and L_perp, found from measuring scattered electrons as a function of scattering angle and energy. The scattering chamber was held at a pressure of 3x10 -7 mbar. A resistively heated oven operating at 800 degrees celsius produced a well collimated calcium atomic beam containing the calcium atoms. The electron gun generated a beam of electrons of well defined momentum, whose energy could be changed from ~5 eV to over 100 eV. At energies less than 20 eV the rate of super-elastic electrons was very low, and so modifications were made to the spectrometer to automate data collection for long operating times without the need for user intervention. A new digitally controlled DC voltage supply was constructed to deliver the correct potentials to the electron-optical elements in the spectrometer. An internal microcontroller enabled supply voltages to be programmed either using the front panel or via an attached computer for automatic optimisation of spectrometer voltages using a simplex algorithm. New data was collected for the collision parameters over the full accessible angular range from 25--140 degrees, at energies of 8, 10 and 65 eV. The data at 8 and 10 eV was taken so as to resolve differences between theoretical models at low energies. Comparisons were made with a relativistic distorted wave calculation, an R-matrix calculation, an R-matrix calculation using B-splines and a convergent close coupling theory. A 2 eV discrepancy was identified in the measured electron energy which was thought to be due to stray fields in the chamber. With this considered, convergent close coupling predictions were found to be in excellent agreement with the experimental data.

This study has shown that season, salinity, temperature and intertidal height all affect the rate up calcium uptake by mussels. For summer-adapted mussels, calcium uptake was found to be temperature dependent over the range of acute temperatures measured (1°-23°C). When subjected to a range of salinities over a three week period, summer-adapted mussels showed calcium-uptake rates which were salinity dependent from 25%-75% SW, and which did not show any increase in uptake rate in salinities greater than 75% SW. For winter-adapted mussels, calcium uptake was temperature independent over a temperature range from 5°-l7°C. At higher and lower temperatures, uptake was reduced. When subjected to a range of salinities over a three-week period, winter-adapted mussels were also unable to compensate for the lower concentration of calcium in the seawater, and did not show any increase in the uptake rate in salinities greater than 75% SW. It was found that high and low intertidal mussels had different calcium uptake rates, and that transplantation could alter the uptake rate of transplanted mussels to the uptake rate of untransplanted controls. In the intertidal zone a gradient of shell size was found, which could be associated with the change in uptake range over the intertidal range. Differences in immersion time between the two. sites could not explain all of the differences in uptake rate, but high intertidal mussels were found to have less total dry weight of soft parts than low mussels, and correcting for this difference accounted for the the remainder of the difference in calcium-uptake rate between the two sites. The soft parts of the mussel were found to become saturated with ⁴⁵Ca after four hours, while the shell accumulated calcium for the duration of the experiment. The mantle and gill tissue held the same amount of calcium when corrected for differences in weight, while the viscera held a greater pool of calcium. Accounting for real increases in the amount of calcium accumulated by the shell showed that the uptake rates reported in this study are about 59% of the absolute uptake rates. / Science, Faculty of / Zoology, Department of / Graduate

Epithelial to mesenchymal transition (EMT) is a process whereby epithelial cells, which act collectively through robust cell–cell interactions, take on mesenchymal characteristics, breaking cell–cell junctions to become solitary, invasive and motile. Our previous results show that a transient increase in calcium influxes through TRP channels at the plasma membrane is required for hepatocyte growth factor (HGF)– stimulated EMT. Since this transient increase requires an intact microtubule cytoskeleton, we propose that HGF stimulation results in the mobilization of calcium channels to the plasma membrane from an intracellular compartment via microtubule–dependent vesicle trafficking. Through immunofluorescence, we show that prior to HGF treatment, TRPV4 localizes to a perinuclear compartment that stains for rab11. After HGF stimulation, this colocalization is reduced and TRPV4 localizes more precisely to fibrous structures. Similarly, rab8 staining is seen throughout the cytoplasm prior to HGF treatment, but localizes primarily to tubular structures after HGF stimulation. This is indicative of endocytic recycling of TRPV4 via rab8. MDCK cells null for rab8 activator, rabin8, were developed using the CRISPR system and then analyzed for changes in epithelial scattering and trafficking of ion channels to the plasma membrane following HGF stimulation. Rabin8 KO cells had a decrease in TRPV4 vesicle trafficking. While rabin8 KO cells did undergo HGF-induced spreading and some disassembly of cell-cell junctions, they lost all motility. Also, HGF-treated rabin8 KO cells had similar calcium levels to untreated WT cells, which had fewer calcium spikes than HGF-treated WT cells. ERK1/2, a known downstream effector of HGF stimulation, has been shown to activate rabin8, and so we tested the effect of an ERK1/2 inhibitor on HGF-induced WT cells as well. These cells had decreased TRPV4 vesicle trafficking and loss of motility, similar to rabin8 KO cells, indicating that ERK1/2 may act upstream of rabin8 and rab8 in this pathway. Our results indicate that TRPV4 undergoes endocytic recycling via rab8 to the cell surface to allow a necessary calcium influx within one hour of HGF stimulation in MDCK cells, leading to EMT.

On May 11th, 2019, atmospheric CO2 levels reached 415 ppm, a number 40% higher than the maximum level ever reached in the 800 000 years prior to the Industrial Revolution. This rise can be directly attributed to human activity, and has been linked to global temperature increase and climate change. Net CO2 emissions continue to rise as economies grow, and in 2018 global emissions reached 37.1 Gt. In order to reach the climate targets identified in the 2015 Paris Agreement, some scientists estimate that the world will need to attain net-zero anthropogenic greenhouse gas (GHG) emissions by 2050. Achieving this goal will require deployment of multiple technologies across multiple sectors. Of particular importance will be reducing or eliminating emissions associated to energy production via combustion of fossil fuels, which account for over 80% of CO2 emissions in G20 countries. One method of achieving this is to displace fossil fuel electricity generation with renewable source generation. Canada currently has 12 GW of installed wind capacity, and although it is the country’s fastest-growing source of renewable electricity, widespread deployment is inhibited by technical challenges including the time variability and geographic dispersion of sources. A potential solution to overcome the challenges facing integration of renewables is grid-scale energy storage. Many storage technologies currently exist at various levels of maturity. Although currently low on the development scale, thermochemical energy storage (TCES) has gained significant interest due to its potential to offer low-cost, short- or long-term storage of high-temperature heat using non-toxic, abundant materials. Several recent works have focused on the potential to pair the calcium looping (CaL) process, which exploits the reversible calcination of calcium carbonate, with concentrated solar power (CSP). This would enable CSP to provide continuous power to the grid while receiving discontinuous solar input, and recent projects have predicted storage cycle efficiencies in the range of 38-46%. As an extension of the work done to date, this project proposes a novel configuration of the CSP-CaL process which may offer advantages over other proposed configurations, including a reduction in process equipment requirements, elimination of pressure differentials between vessels, and a reduction in compression duty during the energy discharge period. A process simulation of the proposed system shows that it is capable of offering comparable storage cycle efficiencies, with the overall efficiency being strongly dependent on the residual conversion of calcium oxide in the carbonator as well as on the efficiencies of the power cycles employed to discharge the stored energy. In addition to the technical challenges that may come with this type of system, social and economic barriers may arise due to the fact that it will require large-scale storage of CO2, mining of natural limestone, and potentially large and complex facilities. All of these challenges must be considered and addressed in order to achieve deployment of this technology within Canada and around the world.

Following neuronal injury, calcium signaling plays a critical role in promoting repair processes. Injury produces an initial cytosolic calcium elevation mediated by calcium entry from the cut site, plasma membrane channels, and intracellular storage compartments. Subsequently, a variety of signaling factors are involved in promoting growth cone formation and axon outgrowth and guidance, some of which include DLK-1, CaMP, CED-3, CED-4, and calreticulin. Specific proteins mediating calcium transport have also been reported to significantly affect regenerative outgrowth, particularly inositol triphosphate receptors, voltage-gated calcium channels, and ryanodine receptors. Given that mitochondria can store intracellular calcium and regulate cytosolic calcium levels, we hypothesized that the mitochondrial uniporter (MCU) may play a significant role in neuronal regeneration. We found that inhibiting calcium entry into the mitochondria via a loss of function mutation in MCU significantly enhances axonal outgrowth following laser axotomy of single neurons in C. elegans. This effect is calcium-dependent, with the MCU mutant regenerative phenotype reverting to baseline levels when mutants are chronically treated with the calcium chelator EGTA. We also find that sub-cellular calcium signals at the axon cut site are significantly reduced in MCU mutants, while basal levels of calcium and axon guidance remain unaffected. These findings suggest that mitochondrial calcium regulation plays a significant role in the regeneration of single neurons, and that inhibition of MCU activity may be a promising avenue for the treatment of clinical syndromes derived from axonal injury, such as spinal cord injury. / 2017-11-03T00:00:00Z

<p></p><p>The<b> </b>L-type VGCC subtypes, including subtypes Ca_v1.1-1.4, have been shown to play critical roles in various cellular activities, including muscle contraction, hormone secretion, and neurotransmitter release. Recent research indicates the potential involvement of Ca_v1.3 in various neurological and psychiatric disorders, such as the early onset of Parkinson’s disease and substance abuse disorders. Non-selective L-VGCC subtype blockers such as dihydropyridines (DHPs) are used to treat hypertension and angina because they potently inhibit Ca_v1.2, but no selective Ca_v1.3 inhibitors have been developed yet. We resolved the molecular determinants to differentiate Ca_v1.2 and Ca_v1.3 in response to DHP nifedipine. Nifedipine IC₅₀ for Ca_v1.2 and Ca_v1.3 are 22nM and 289nM determined by whole-cell patch-clamp. We identified two significant amino acids, Ca_v1.3/M1030 to Ca_v1.2/V1036 in the transmembrane IIIS5 and Ca_v1.3/S1100 Ca_v1.2/A1106 in the extracellular IIIS-3P loop, to differentiate the subtype affinity to nifedipine. </p> <p>We found that the Ca_v1.3/II-III loop fused to eGFP decreased glucose-activated action potential (GSAP) frequency by ~80% in the pancreatic β-cell. We introduced several synthetic peptides, and peptide P3-1 from C-terminal induced a -16mV shift in V_1/2 inactivation with an EC₅₀ of 231nM. P3-1 contains a protein kinase G (PKG) phosphorylation site (RRISE) required for PKG inhibition of Ca_v1.3 current but not conserved in Ca_v1.2. We found that the shift in V_1/2 inactivation induced by co-expression of Ca_v1.3 with the Ca_v1.3/II-III loop/GFP requires the presence of a Ca_vβ subunit, and Ca_vβ₃ also exhibits selectivity over other β subunits. Significantly, P3-1 shifts the Ca_v1.2 inactivation to a more positive voltage when co-expressed with either Ca_vβ_2aor Ca_vβ₃, demonstrating the ability of P3-1 to differentiate Ca_v1.2 and Ca_v1.3 in a Ca_vβ-dependent manner.</p> <p><b> </b>Failure of pancreatic β-cells to secrete enough insulin to maintain glucose homeostasis is a hallmark of Type 2 diabetes. However, the consequences of the dysregulation of the endoplasmic reticulum (ER) Ca²⁺ channel ryanodine receptor-2 (RyR2) in pancreatic β-cells are not fully understood. Therefore, we characterized the electrical activity in INS-1 in which RyR2 has been deleted via CRISPR/Cas9 gene editing. We observed a decreased level of IP₃ receptor binding protein (IRBIT) in RyR2^KO INS-1 cells and generated IRBIT^KO INS-1 cells. VGCC current density in RyR2^KO doubled compared to controls and was also elevated in IRBIT^KOcompared to control cells. All HVA Ca²⁺ channels were upregulated, determined by fractional current blocked by nifedipine. We also found that GSAP frequency is doubled by RyR2 deletion due to failure to activate apamin sensitive SK (small conductance calcium-activated potassium) channels. </p><br><p></p>

Identification of patients with suboptimal nutritional status allows for early treatment intervention. Currently, no definitive test of nutritional status exists. Therefore, this study was conducted to identify possible functional indicators of acute nutritional deprivation. The effects of total nutritional deprivation and subsequent refeeding on lymphocyte functions and subpopulations were examined in 23 healthy cats. Peripheral blood samples were analyzed at various times during fasting and refeeding periods. During the fasting period, decreases were observed in leukocyte number (day 4; p < 0.04), lymphocyte number (p < 0.02), CD4+ cells (day 4; p < 0.06), CD4:CD8 ratio (0 hours; p < 0.004), and mitogen stimulated CD4:CD8 ratio (72 hours; p < 0.15) during the fasting period as compared to baseline. Increases were seen in CD4+ cells (day 7; p < 0.09), CD8+ cells (day 7; p < 0.04) and intracellular calcium (day 4; p < 0.02) as compared to baseline. During the refeeding period increases (p < 0.05) were observed in leukocyte number, CD4+ cells, CD8+ cells, lymphocyte proliferation (p < 0.07) and lymphocyte number (p < 0.004) as compared to day 7. These findings suggest that 7 days starvation had immunosuppressive effects on cats which were alleviated during 7 days refeeding. The use of CD4:CD8 ratio in conjunction with intracellular calcium flux may be useful as indices of nutritional status. / Master of Science