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This thesis begins with the introduction of solvents and their classification. The two solvent system studied here are switchable polarity solvents (SPS). A switchable polarity solvent is a liquid where its polarity can change between two forms by a trigger. These two solvent systems have several similar characteristics. First, they both require CO2 as the switching agent, which can be switched back by its removal with heat or N2. The first project is the continuation of previous work with using an amidine and alcohol mixtures as a switchable polarity solvent. The second project was the development of a new switchable polarity solvent that is based on the reaction of a secondary amine with CO2. Both solvent systems are fully characterized by many analytical techniques and examples of applications in chemical reaction and separation are outlined. The final project involves using these solvent systems, among others, in the separation of soybean oil. The aim was to use SPS technology to extract soybean oil from the bean flakes, and then separate the oil from the extracting solvent. / Thesis (Master, Chemistry) -- Queen's University, 2008-02-07 15:21:31.499

Thorough understanding of the electronic and optical properties of single-walled carbon nanotubes (SWCNTs) will no doubt benefit future technological applications. Since the discovery of band gap photoluminescence from isolated semiconducting SWCNTs, significant progresses in studying the optical properties of SWCNTs have been made (e.g. linear polarization along the tube axis for the absorption and emission of light, excitonic nature in SWCNT excitation). However, there are still several controversial parameters of SWCNTs (e.g. quantum efficiency, absorption cross section, radiative lifetime, and Auger recombination lifetime). With the advancement in SWCNT sample preparation, studies of SWCNT intrinsic properties have shifted from ensemble to a single tube level, in which the ambiguities in elucidating intrinsic properties posed by the assortment of different tube species can be minimized. By examining individual SWCNTs suspended in air, in contrast to micelle-encapsulated SWCNTs, we believe that the environmental effects can be reduced. This thesis will demonstrate the capability of doing spectroscopy on a single semiconducting air-suspended SWCNT. In continuous-wave excitation, the photoluminescence excitation map and high resolution photoluminescence (PL) image of a SWCNT can be constructed, and PL polarization is proven. Quantum efficiency of 5% is experimentally estimated for (9,8) and (10,8) chiral SWCNTs. Pulse excitation allows us to study the intrinsic exciton dynamics of a SWCNT. To gain insight into exciton nonlinear decay processes, PL saturation in pump power dependence measurement is investigated and compared to the simulated results from stochastic models of exciton dynamics. Femtosecond excitation correlation spectroscopy with 150 fs time resolution is employed to time-resolve the PL of a single tube suspended in air. / Thesis (Master, Physics, Engineering Physics and Astronomy) -- Queen's University, 2008-08-29 13:10:49.045

Carbon filled columns were built and tested as prototype radon filters. The length of time taken for a pulse of radon to travel from one end of the filter to the other was measured using nitrogen, and then air as the carrier gas. Its dependency on two variables were investigated: temperature of the tube and the flow-rate of carrier gas through the column. Using Height Equivalent to a Theoretical Stage (HETS) the carbon was found to have a adsorption constant (ka) of 9.7 ± 1.7 L/g at STP, and a binding energy value (Eb) of (30±1) kJ/mol. The radon concentration in the carrier gas was measured using a silicon detector housed in a metal chamber with a charged collector plate. Most filter tests measured Rn concentrations by measuring levels of the daughter atom 218Po. A computer simulation was created for aspects of both the working detector chamber and a prototype detector chamber. The charged fractions of 218Po and 214Po were calculated by comparing the Monte Carlo simulation to data obtained from the detectors. The positively charged fraction of 218Po was found to be (80 ± 9)% and 214Po was (110 ± 180)%. / Thesis (Master, Physics, Engineering Physics and Astronomy) -- Queen's University, 2008-08-29 16:38:33.442

Semiconducting single-walled carbon nanotubes (S-SWCNTs) have direct band gaps with a range of 0.5 to 2 eV depending on the SWCNT chirality. The photoluminescence (PL) quantum efficiency and the carriers’ radiative lifetime have been previously studied but neither of them have been confirmed due to the large variation resulting from ensemble averaging, environmental effects, SWCNT defects, and SWCNT bundles. For example, quantum efficiency was estimated to be 0.01% to 7% and radiative lifetime was estimated or calculated to be 10 to 100 ns. In this thesis, we study absorption cross section, PL quantum efficiency and exciton relaxation dynamics from single air-suspended S-SWCNTs and extract “intrinsic” S-SWCNT properties. The photo-excited carriers are electron-hole pairs (called excitons) in a SWCNT due to the strong Coulomb interactions in the nm-scale system. We selected relatively bright and less defected S-SWCNTs on our samples for investigation. For each SSWCNT, the tube length, orientation, absorption and emission spectra were recorded. Experimentally, we observed that PL from a single S-SWCNT increases linearly at low excitation intensity (linear regime) and saturates at higher intensity (saturation regime). We also studied the exciton relaxation dynamics on each S-SWCNT by femtosecond excitation correlation (FEC) spectroscopy and resolved two relaxation time constants which were independent of the excitation intensity. We compare the simulation results based on a stochastic model to the experimental data and extract essential parameters including S-SWCNT unitless absorption coefficient (typically 0.02 to 0.06), PL quantum efficiency (typically 7 to 20 %) and exciton relaxation time constants. We observed very fast nonlinear exciton-exciton annihilation rate (>(2 ps)^−1) in a typical 5 μm-long S-SWCNTs. The exciton dynamics were consistent from 4 different S-SWCNTs in the saturation regime and the average total exciton number per pulse per tube in this saturation regime ranges from 2 to 12. Compared to past work, the results (PL saturation curves and FEC data) between S-SWCNTs are very consistent which supports our belief that we are studying “intrinsic properties”. We found a higher absorption coefficient, and higher PL quantum efficiency of S-SWCNTs compared to previous work. We also observe very fast nonlinear exciton-exciton annihilation in a relatively longer S-SWCNT and at lower exciton numbers. / Thesis (Master, Physics, Engineering Physics and Astronomy) -- Queen's University, 2009-01-08 20:38:56.433

The present work deals with the calculation and the investigation of possible reductions of CO2 emissions in manufacturing a metal formed product. The industrial sector plays a significant role in the recent increase of the oncentration of Greenhouse Gases in the atmosphere, which is responsible for the advancing global warming. As an answer to fiscal and financial intervention of government policies aimed at counteracting this phenomenon, the environmental impact of products became a key aspect of a company’s strategy. However, literature still lacks effective methods and quantitative studies that look into the details of a single manufacturing process, discussing its environmental aspects and how they can be influenced by changes in the technological parameters. In an attempt to do that, an example of quantification and minimization of the carbon emissions occurring during the two manufacturing steps of the fabrication of an Al 6061 disc is provided. Electrical energy consumption occurring during the shearing and the upset forging of a billet was found by means of nonlinear finite element analysis and converted into CO2 emissions with a carbon emission signature value (CES). Environmental impact and frictional properties of both traditional lubrication and two non-conventional ecologically benign lubricants (palm oil ester and used cooking oil ester) were experimentally tested and are included in the study. A gradient-based optimization algorithm was implemented to determine the optimal geometry of the billet before the compression as well as the lubricant that minimize the total carbon emissions, within the proper technological limitations and constraints on the final product quality. A clear and effective method which would represent an auxiliary decision tool for a manufacturer in the metal forming sector is hereby presented. Results show that the selection of the manufacturing options can have an influence of more than 13% on the overall CO2 emission. / Thesis (Master, Mechanical and Materials Engineering) -- Queen's University, 2009-12-19 16:39:12.071

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