The peak efficiency range for CdTe solar cells is between 500-700nm; however efficiencies are limited at wavelengths shorter than 500nm due to the fact that at higher energies, most photons are absorbed in the CdS layer of the module and cannot contribute to the cell current. This means that incident photons with higher energies are ‘wasted’ as they are not efficiently absorbed by the cell. Luminescent downshifting (LDS) is a third-generation photovoltaic technology in which an external layer applied to the front surface of the cell absorbs high energy photons and re-emits them towards the cell at energies where they are more efficiently absorbed, thus avoiding front surface loss mechanisms. This research project investigates the use of cerium and terbium co-doped silicon oxide thin films grown using electron cyclotron resonance plasma enhanced chemical vapour deposition (ECR PECVD) as a luminescent down-shifting layer. Post-deposition annealing in a quartz tube furnace caused the formation of cerium disilicate (Ce2Si2O7) nanocrystallites, which were found to strongly absorb incident light at wavelengths below 360 nm and efficiently sensitize Tb3+ ions in the film for re-emission. The effect of annealing time and sample composition on physical and optical properties was studied. Film compositions were determined through Rutherford backscattering spectrometry, revealing an incremental increase in rare earth concentration. Photoluminescence measurements showed a distinct Tb3+ peak around 550nm, which is close to the ideal efficiency wavelength for CdTe photovoltaics. Variable Angle Spectroscopic Ellipsometry measurements were used to determine the index of refraction of as-deposited and annealed films. UV-Visible absorption spectroscopy and transmission ellipsometry measurements showed a sharp increase in absorption around 400nm confirming wide separation between absorption and emission bands. When LDS films were coupled with thin film CdTe, subsequent absorption spectroscopy and transmission measurements showed stronger absorption at short wavelengths, as anticipated. / Thesis / Master of Applied Science (MASc)

Corrosion is an unstoppable process that occurs spontaneously in many areas of industry, specially, oil and gas industries. Therefore, the need of developing protective coating to lower the cost of corrosion is very consistent. Among different methods, electrodeposition has been a popular method since it offer many advantages such as low cost, ability to control the surface and thickness of the coating, ability to perform at low temperature and pressure, and very convenience. Ceramic nanoparticles have been widely incorporated into metal coating and used as a protective layer to improve both corrosion and hardness properties. Diazonium synthesis was used to modify cerium oxide nanoparticles by grafting with ferrocene for use in nickel nanocomposite coating. Citric acid and citrate salt were used as stabilizing ligands for yttrium oxide and praseodymium oxide nanoparticles in nickel plating solution to prevent the formation of hydroxide, thus, higher amount of nanoparticles was able to incorporate into nanocomposite coatings. These fabricated coatings were evaluate for the corrosion and mechanical properties using many different instruments and electrochemical techniques. As modified cerium oxide, stabilized yttrium oxide or praseodymium oxide added into nickel coatings. The results showed an increase in hardness and corrosion resistance leading to the overall improvement compare to pure nickel coating.

Indicates numerous railroad lines from Florida to New York and west to the Mississippi, including line from Spartanburg to Elkhorn City in red. M.B. Brown Printing and Binding Company, N.Y. No scale provided. / https://dc.etsu.edu/rare-maps/1157/thumbnail.jpg

Rare bleeding disorders are a group of inherited conditions caused by a deficiency of blood coagulation factors. Due to the low prevalence of these conditions in the general population, there is a scarcity of data to make informed, evidence-based clinical decisions. In this population who are highly susceptible to excessive bleeding, surgeries and invasive procedures pose an additional level of risk for bleeding-related and non-bleeding-related complications, especially in the perioperative period. The data scarcity in patients with rare bleeding disorders is further compounded by an infrequent rate of invasive procedures, sometimes attributed to the hemostatic challenges faced by such interventions among other factors. To address the problem of insufficient data for healthcare decision-making, as well as the assessment of perioperative outcomes in this population, this thesis explores the use of routinely collected data for the creation of a novel surgical database used for the assessment of perioperative hemostasis, complications, and initial surgical plan deviations in patients with rare bleeding disorders. Across five chapters, this thesis provides the methodology for the creation of the Indiana Hemostasis and Thrombosis Center (IHTC) Surgical Database, a descriptive analysis of the population and procedures, and assessment of perioperative outcomes. Approaches to ensure the validity of study results including confounder adjustment by variable selection methods, data quality improvement, missing data description, and imputation methods, were explored. Evidence from randomized controlled was also reviewed using Cochrane methodology to summarize the efficacy of clotting factor concentrates for the prevention of bleeds and bleeding-related complications in patients with hemophilia. Based on findings from the different approaches (observational study designs, randomized controlled trials, and systematic review methodology), recommendations were made regarding methodological and analytical considerations required to ensure valid and reliable perioperative outcome assessment in patients with rare bleeding disorders. The following provides a brief outline of each chapter. Chapter 1 is an introduction that outlines each of the studies in this thesis. Chapter 2 is a descriptive overview of the design, structure, and exploratory analysis of data captured in the IHTC-Surgical Database over a 21-year period. Chapter 3 is a retrospective cohort study that assessed the association between inhibitor status and perioperative hemostasis, complications, and initial surgical plan deviations in patients with hemophilia A and B. Chapter 4 is a systematic review that examined the efficacy of clotting factor concentrates for the prevention of bleeds and bleeding-related complications in patients with hemophilia. Chapter 5 outlines key findings, limitations, implications of the research in this thesis, and methodological considerations for the assessment of perioperative outcomes in patients with bleeding disorders. / Thesis / Doctor of Philosophy (PhD)

<p> The isotopic composition and concentration of dissolved helium have been measured in over 250 samples of Atlantic and Pacific seawater. The helium isotope ratios were measured using a double collection "static" mass spectrometer specifically designed and constructed for this purpose. The helium and neon contents of 118 of these samples were determined using the isotope dilution technique, and the helium contents of the remaining samples were determined by peak-height comparison with standard air aliquots. Krypton and xenon concentrations were measured by isotope dilution for the Pacific samples. </p> <p> Two sources of excess nonatmospheric ³He are discerned in the Atlantic Ocean: a primordial component and a component produced by in situ decay of bomb-produced tritium. The former component occurs in three distinct features; two emanating from the south at 1000 m and greater than 4000 m depths, and one emanating from the north at about 3000 m depth. The spatial properties of these features are studied in the framework of simple models. The latter, or "tritiugenic" component is coupled with tritium concentrations measured by others to obtain Tritium-helium Ages, the characteristics of which are compared with hydrographic features. For example, the spreading velocity of the Mediterranean Water is determined to be ⪝ 1.5cm sec⁻¹ in the North-Western Atlantic. </p> <p> The helium and neon concentrations measured in Atlantic Waters indicate that significant variations occur for helium contents, both as a function of depth and latitude. The Antarctic Bottom Water appears to be a source of excess helium. </p> <p> In the Pacific, the distribution of excess ³He is shown to be consistent with injection of primordial ³He into the Deep and Bottom Waters from the East Pacific Rise. The characteristic mid-depth maximum seen in the helium isotope ratio anomaly profiles is shown to be a circulational feature. Upper and lower limits on the amount of excess nonatmospheric ⁴He are set at 5.5 and 2.6% respectively. Application of the simple one-dimensional diffusive-advective model indicate an upward flux of 6±2 and 1.1 ± 0.5 × 10⁶ atoms/cm²/sec for ³He and ⁴He respectively. </p> Pacific seawater is, on the average, 16 and 31% supersaturated in krypton and xenon respectively. Although there is no known process that is capable of such enrichments, the spatial distribution of the krypton and xenon concentrations indicate that a significant amount of the enrichment occurs in situ in Pacific Deep Waters. </p> / Thesis / Doctor of Philosophy (PhD)

<p> The mineral eudialyte from Seal Lake, Labrador, was analyzed by means of x-ray fluorescence analysis for the rare earths La, Ce, Pr, Nd, Sm, Gd, Y and also for the element Zr. Samples were prepared by two methods: a) whole mineral powder being compressed into pellets, and b) the dissolved mineral being put through an ionic exchange process to eliminate interfering ions before compressing into pellets for analysis. The results are compared with published data.on other eudialyte occurrences. </p> / Thesis / Bachelor of Science (BSc)

The rare earths form series of compounds which are known for several elements but end abruptly or undergo a change of structure at some member of the series. The diantimonides are one such series. Sb-Sb repulsion becomes stronger as the rare earth size decreases and the previously known series ended at Sm. It was felt that high pressure would overcome the Sb-Sb repulsion and allow bonding to form stable or metastable compounds not possible by ordinary techniques. Synthesis studies were carried out on mixtures of antimony with all the rare earths except Pm and with Sc and Y. The known diantimonide series was extended two elements to GdSb2 and TbSb2. A new orthorhombic structure was found in the series for GdSb2, TbSb2, DySb2, HoSb2, ErSb2, TmSb2 and YSb2. Attempts to synthesize diantimonides of Sc, La, Ce, Eu and Lu were not successful. Reaction products for one to two molar mixtures of rare earth to antimony were determined for all the elements studied as a function of pressure and temperature up to 70 kilobars and 1800 °c. Products were identified by their X ray diffraction patterns. Only Sb plus the rare earth oxide were found for La, Ce and Eu. The oxygen apparently migrated into the sample from the pyrophyllite tetrahedrons. For Sc and Lu only the monoantimonides plus Sb were found. Only LaSb2 type diantimonides were found for Pr, Nd, Sm and Yb. Complex reaction product diagrams were obtained for mixtures of Gd, Tb, Dy, Ho, Er and Tm with Sb. Two different orthorhombic structures were found for GdSb2 and TbSb2. All compounds in the rare earth - antimony systems were silver-grey and metallic in appearance. All reacted almost the same with acids, H2O and NH4OH but did not react with organic reagents. They were stable to the atmosphere. The density of each compound was determined. Most of the heavy rare earth sesquisulfides are known in a monoclinic form except Yb2S3 which is orthorhombic and Lu2S3 which is rhombohedral. The light rare earth sesquisulfides are commonly found in a Th3P4 type cubic structure. Dy2S3 is found in both cubic and monoclinic forms. Since the cubic form is more dense and higher coordinated it seemed probable that the monoclinic form of the heavy rare earth sesquisulfides could be converted to the cubic form by high pressure techniques. Dy2S3, Ho2S3, Er2S3, Tm2S3, Yb2S3 and Y2S3 were all converted to the cubic form at 77 kilobars and 2000 °C in a cubic press. Lu2S3 was about 50 per cent converted to the cubic form at these conditions. The results of this investigation suggest that other series of rare earth compounds could be extended by high pressure techniques and several possibilities are discussed.

No description available.

No description available.

No description available.