Glaucoma is a leading cause of world blindness, often associated with elevated eye pressure. Current glaucoma treatments aim to lower eye pressure by improving aqueous humor outflow from the eye. Ocular lymphatics have been demonstrated to contribute to aqueous humor outflow in human and sheep. It is not known whether any glaucoma drugs target this lymphatic drainage. The mouse is a valuable model with similar aqueous humor dynamics and pharmacology as human. Using in vivo hyperspectral fluorescence imaging combined with intracameral quantum dot injection, we identified an ocular lymphatic drainage in mouse. Immunofluorescence and confocal microscopy revealed lymphatic channels in the ciliary body, sclera, and orbit that may be responsible for this lymphatic drainage. We showed that latanoprost, a prostaglandin F2α analog widely used to treat glaucoma, increases this ocular lymphatic drainage. Our findings provide the framework for future development of novel glaucoma drugs that stimulate the ocular lymphatic drainage.

Quantum dots (QDs), which are formed by a double barrier resulting in resonant-state electrons, are one of the ideal experimental tools to confine electrons and to study the tunneling of an electron through a double barrier in a one-dimensional transmission channel. In our research, we have two laterally coupled QDs in an Aharonov-Bohm (AB) ring geometry in which the coupling between two dots can be controlled. We use the tight-binding model to compute the exact transmission amplitude of an electron through the discrete quasi-bound states in coupled QDs embedded in an AB ring. We study the effect of magnetic flux on the transmission as well as explore how the inter-dot coupling changes the resonant states in QDs. We confirm that the lead-dot couplings involve the lifetime of the quasi-bound states in a symmetrical interference experiment. By tracing the position of the resonances of quasi-bound states, we can predict the shift of bonding and antibonding states for both single and multiple state-identical QDs as a function of energy levels and inter-dot coupling parameters. / Electron transport and resonance phenomena through QDs -- The tight-binding model -- Electron transport in a double quantum dot -- Transmission throught multiple states in a coupled quantum dot. / Department of Physics and Astronomy

A method of generating and testing pseudopotentials will be presented. This required the development of PPTester, a custom software program to analyze and quantify various parameters. These methods were first used to study bulk Si and verify the installation and performance of SIESTA. Plots, which agreed with published results, for band gap and charge density were generated.Next, pseudopotentials for Cd and Se were constructed and tested. Two separate Cd potentials were evaluated. Electronic structure calculations for two, four and six atom small cadmium selenide (CdSe) colloidal quantum dots were performed. The changes in geometry of initial versus relaxed atomic positions of these systems were evaluated. Output values of the electronic structure calculation, for example Fermi energy, were analyzed. / Department of Physics and Astronomy

The defects and fault tolerance study is essential in the QCA devices in order to know its characteristics. Knowing the characteristics, one can understand the flow of information in a QCA system with and without manufacturing and operational defects. The manufacturing defects could be at device level or cell level. At the device level, the cell could be rotated, displaced vertically or horizontally, the cell could be missing or the size of the cell could be different. At the cell level, there could be a missing dot, dot could be displaced from its position or the size of the dots could be different. The operational defects are due to its surrounding, such as temperature or stray charge. Each of these defects and fault tolerances can be studies in detail in order to find the optimum working conditions where the information can be safely transmitted to the appropriate locations in the device.The theoretical studies have shown that at absolute temperature and without any defect, the QCA devices are operational. But it is almost impossible to manufacture a perfect or defect free device, and also it is impractical to think about operating a system at absolute zero temperature environment.Therefore, it is important to investigate the fault tolerant properties with defects and higher temperatures to see how far the QCA device can operate safely. Many studies have been done to investigate the fault tolerant properties in QCA devices. However, these studies have not completely exhausted the study of defects and temperature effects. In this study, the dot displacement and missing dots with temperature effects are investigated for the basic QCA devices and a Full Adder. In order to study fault tolerant properties, the existing theoretical model and computer simulation programs have been expanded and used. The defect characteristics have been simulated using normal distribution. / Department of Physics and Astronomy

We present a theoretical study of quasi-adiabatic clocking and thermal effect in Quantum-dot Cellular Automata (QCA). Quasi-adiabatic clocking is the modulation of an inter-dot potential barrier in order to keep the QCA cells near the ground state throughout the switching process. A time-dependent electric field is calculated for arrays of charged rods. The electron tunneling between dots is controlled by raising and lowering a potential barrier in the cell.A quantum statistical model has been introduced to obtain the thermal average of polarization of a QCA cell. We have studied the thermal effect on QCA devices. The theoretical analysis has been approximated for a two-state model where the cells are in one of two possible eigenstates of the cell Hamiltonian. In general, the average polarization of each cell decreases with temperature and the distance from the driver cells. The results demonstrate the critical nature of temperature dependence for the operation of QCA. / Department of Physics and Astronomy

Forster theory of energy transfer is applied in diluted systems, and yet it remains unknown if it can be applied to the dense media. We have studied the exciton transfer in one-dimensional (1-D) close-packed pure and mixed quantum dot (QD) array under different models and two-dimensional (2-D) perfect lattice. Our approach is based on the master equation created by treating the exciton relaxation as a stochastic process. The random parameter has been used to describe dot-to-dot distance variations. The master equation has been investigated analytically for 1-D and 2-D perfect lattices and numerically for 1-D disordered systems. The suitability of Forster decay law on the excitation decay of close-packed solid has been discussed. The necessity to consider the effect of the further nearest interdot interactions has been checked. / Department of Physics and Astronomy

Multijunction solar cells made from a combination of CQDs of differing sizes and thus bandgaps are a promising means by which to increase the energy harvested from the Sun’s broad spectrum. In this dissertation, we first report the systematic engineering of 1.6 eV PbS CQD solar cells, optimal as the front cell responsible for visible wavelength harvesting in tandem photovoltaics. We rationally optimize each of the device’s collecting electrodes—the heterointerface with electron accepting TiO2 and the deep-work-function hole-collecting MoO3 for ohmic contact—for maximum efficiency. Room-temperature processing enables flexible substrates, and permits tandem solar cells that integrate a small-bandgap back cell atop a low thermal-budget larger-bandgap front cell. We report an electrode strategy that enables a depleted heterojunction CQD PV device to be fabricated entirely at room temperature. We develop a two-layer donor-supply electrode (DSE) in which a highly doped, shallow work function layer supplies a high density of free electrons to an ultrathin TiO2 layer via charge-transfer doping. Using the DSE we build all-room-temperature-processed small-bandgap (1 eV) colloidal quantum dot solar cells suitable for use as the back junction in tandem solar cells. We further report in this work the first efficient CQD tandem solar cells. We use a graded recombination layer (GRL) to provide a progression of work functions from the hole-accepting electrode in the bottom cell to the electron-accepting electrode in the top cell. The recombination layers must allow the hole current from one cell to recombine, with high efficiency and low voltage loss, with the electron current from the next cell. We conclude our dissertation by presenting the generalized conditions for design of efficient graded recombination layer solar devices. We demonstrate a family of new GRL designs experimentally and highlight the benefits of the progression of dopings and work functions in the interlayers.

Engineering particles at the nanoscale demands a high degree of control over process parameters during synthesis. For nanocrystal synthesis, solution-based techniques typically include application of external convective heat. This process often leads to slow heating and allows decomposition of reagents or products over time. Microwave-assisted heating provides faster, localized heating at the molecular level with near instantaneous control over reaction parameters. In this work, microwave-assisted heating has been applied for the synthesis of II-VI semiconductor nanocrystals namely, ZnO nanopods and CdX (X = Se, Te) quantum dots (QDs). Based on factors such as size, surface functionality and charge, optical properties of such nanomaterials can be tuned for application as sensors. ZnO is a direct bandgap semiconductor (3.37 eV) with a large exciton binding energy (60 meV) leading to photoluminescence (PL) at room temperature. A microwave-assisted hydrothermal approach allows the use of sub-5 nm ZnO zero-dimensional nanoparticles as seeds for generation of multi-legged quasi one-dimensional nanopods via heterogeneous nucleation. ZnO nanopods, having individual leg diameters of 13-15 nm and growing along the [0001] direction, can be synthesized in as little as 20 minutes. ZnO nanopods exhibit a broad defect-related PL spanning the visible range with a peak at ~615 nm. Optical sensing based on changes in intensity of the defect PL in response to external environment (e.g., humidity) is demonstrated in this work. Microwave-assisted synthesis was also used for organometallic synthesis of CdX(ZnS) (X = Se, Te) core(shell) QDs. Optical emission of these QDs can be altered ased on their size and can be tailored to specific wavelengths. Further, QDs were incorporated in Enhanced Green-Fluorescent Protein – Ultrabithorax (EGFP-Ubx) fusion protein for the generation of macroscale composite protein fibers via hierarchal self-assembly. Variations in EGFP- Ubx·QD composite fiber surface morphology and internal QD distribution were studied with respect to (i) time of QD addition (i.e., pre or post protein self-assembly) and (ii) QD surface charge — negatively charged QDs with dihydrolipoic acid functionalization and positively charged QDs with polyethyleneimine coating. Elucidating design motifs and understanding factors that impact the protein-nanoparticle interaction enables manipulation of the structure and mechanical properties of composite materials.

Thesis (Ph.D.)--York University, 1999. Graduate Programme in Chemistry. / Typescript. Includes bibliographical references (leaves 155-161). Also available on the Internet. MODE OF ACCESS via web browser by entering the following URL: http://wwwlib.umi.com/cr/yorku/fullcit?pNQ43453

Thesis (PhD) - Swinburne University of Technology, Centre for Atom Optics and Ultrafast Spectroscopy, 2007. / Thesis submitted in fulfilment of the requirements for the degree of Doctor of Philosophy, Centre for Atom Optics and Ultrafast Spectroscopy, Swinburne University of Technology, 2007. Typescript. Bibliography: p. 122-144.