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Quest toward the Design and Synthesis of Functional Metal-Organic Materials (MOMs): A Supermolecular Building Layer Approach (SBL)Mouttaki, Hasnaa 02 April 2015 (has links)
Metal-Organic Materials (MOMs) represent an important division of coordination chemistry. They are self-assembled through the linking of metals with organic ligands. They gained their spotlight among scientists for their aptitude for design and facile synthesis via their multi-component coordination, and their readiness to functionalization. MOMs have been targeted for specific industrial and environmental applications such as gas storage, catalysis and CO2 sequestration.
Throughout the past decade, studies have been conducted to develop systematic approaches toward the design and synthesis of functional MOMs. Their synthesis from targeted building units has facilitated their rational design and functionalization. The Molecular Building Block (MBB) approach was first developed to direct the design of MOMs from preset building blocks with specific connectivity amenable to form the overall MOM structure with the desired topology. These building blocks are easily constructed in situ through the chelation of multifunctional ligands (i.e, carboxylic acid, amine, etc) to single ion or cluster metals such as dinuclear copper paddlewheel, and basic zinc acetate. As complexity and applications for MOMs increased, a new approach was developed through the utilization of Supermolecular Building Blocks (SBBs) for the assembly of more complex and higher connected MOM structures. The SBB approach is implemented through the formation of highly coordinated metal-organic polyhedra (i.e, small rhombihexahedron, cuboctahedron, etc) which are further linked by organic ligands to construct functional porous materials with the desired net topology.
In this work, we focus on the implementation of a new design approach based on utilizing targeted [M(R-BDC)]n 2D layers as building blocks, i.e Supermolecular Building Layers (SBLs). We target well-known 2D layers that are amenable to pillaring through organic building blocks with specific geometries (i.e quadrangular, hexangular) in order to rationally design and synthesize functional porous metal-organic materials. These SBLs are derived from multifunctional ligands capable of both directing the formation of the 2D layers and pillaring to construct the overall targeted 3D structures with the desired topology (i.e, tbo-MOMs, eed-MOMs, mmm-MOMs, bor-MOMs, and eef-MOMs). Ultimately, we construct isostructural, and isoreticular materials which show potential for many applications such as gas storage, gas separation, and catalysis. These materials have been targeted through the rational choice of specific ligands and proper metals which we recognized to have the capability and the functionality to direct the construction of the desired functional materials and to reach our research goals.
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Nest characteristics, breeding dispersal, and nest defence behaviour of Northern Flickers in relation to nest predationFisher, Ryan Jeffrey 28 April 2005
I studied nest characteristics, breeding dispersal, and nest defence behaviour of Northern Flickers (<i>Colaptes auratus</i>, hereafter flickers) in central interior British Columbia with respect to nest predation. My research focused on three questions: (1) Are there nest characteristics associated with the risk of nest predation and nest loss to European Starlings (<i>Sturnus vulgaris</i>)? (2) Does nest predation influence breeding dispersal? (3) Do parental attributes influence nest defence behaviour? <p> An examination of flicker nest-site characteristics at five spatial scales revealed that nests were safer from mammalian predators (N=81) when they were higher, concealed by vegetation, farther from continuous coniferous forest blocks, and contained fewer conifers within the nesting clump. Proximity to conifers increased predation risk, but nests safe from competitors (N=18) were closer to coniferous forest blocks and contained a higher percentage of conifers in the nesting clump. Flickers face a trade-off between being safe from predators and safe from competitors. <p> Nesting success did not influence between-year breeding dispersal by 159 male or 76 female flickers. Because nests and forest clumps were not predictably safe from predators, benefits of dispersing likely outweigh costs. Other factors such as mate-switching, nest ectoparasites, and a fluctuating food source may play larger roles in dispersal than nest predation. Within years, 73% of pairs switched nest sites after their first attempt failed due to predation (N=37); however, there was no reproductive advantage for these pairs compared to pairs that remained at their original nest. Stressful encounters with predators involving nest defence may trigger dispersal, although it seems to offer no greater nest success. Of 24 flicker pairs presented with a control model before egg-laying, 3 pairs abandoned their nest, whereas 4 out of 24 pairs presented with a squirrel model abandoned their nest. This suggests that a one-time encounter with a nest predator is not a sufficient deterrent against continued nesting. Rather, costs of finding and excavating or renovating a new cavity may cause individuals to tolerate some risk in nesting at a location with an active predator. <p> In experimental trials (N=94), intensity of nest defence behaviour against a model predator was not related to the sex, age, body size, and body condition of the defending adult(s). The sexes may have behaved similarly because they are similar in size and have similar survival patterns. Costs and benefits of nest defence for flickers of different ages may also be equal because flickers are relatively short-lived and their survival rate is not linked with age. Brood size of the defending adult was also unrelated to the intensity of nest defence. If flickers have adjusted their clutch size in relation to the number of young for which they can optimally provide care, then no effects of brood size on nest defence behaviour should be recorded, as was the case here.</p>
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Fluid Dynamic and Performance Behavior of Multiphase Progressive Cavity PumpsNarayanan, Shankar Bhaskaran 2011 August 1900 (has links)
It is common for an oil well to produce a mixture of hydrocarbons that flash when exposed to atmospheric pressure. The separation of oil and gas mixtures on site may prove expensive and lead to higher infrastructure and maintenance costs as well. A multiphase pump offers a good alternative with a lower capital cost and increased overall production.
A Progressive Cavity Pump (PCP) is a positive displacement pump type that can be used to pump a wide range of multiphase mixtures, including high viscosity fluids with entrained gas and solid particles in suspension. Despite its advantages, a PCP has a reduced ability to handle high gas-liquid ratios due to limitations of its elastomeric stator material required to overcome thermo and mechanical effects. Also the efficiency decreases significantly with increases in gas volume fractions and reduced differential pressures.
The current study focuses on studying the behavior of this unique pump in a wide range of GVFs and studying the effect of this ratio on overall efficiency, temperature and pressure distribution on the stator. The pump exhibits vibration issues at specific differential pressures and they have been studied in this work. This can be of critical value as severe vibration issues can damage the pump components such as couplings and bearings leading to high maintenance costs.
Another important issue addressed by this research is the behavior of this pump in transient conditions. Oil well production is highly unpredictable with unexpected rises and drops in GVFs. These transient conditions have been simulated by varying the GVF over wide ranges and studying the pump's behavior in terms of load, temperature rises and instantaneous pressure profiles on the pump stator.
This thesis provides a comprehensive study of this pump, its operating ranges and behavior in off-design conditions to assist oil and gas exploration ventures in making an informed choice in pump selection for their applications based on field conditions.
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Transfer Cavity Stabilization Using the Pound-Drever-Hall Technique with Noise CancellationTorabifard, Mozhgan 24 January 2011 (has links)
A system for exciting Rubidium atoms to Rydberg states has been constructed to study the interactions between them and metal surfaces. This thesis describes a method to reach the f Rydberg series using diode lasers. Since the diode lasers need to be frequency stabilized for this excitation, a transfer cavity stabilization method was implemented using the Pound-Drever-Hall technique.
To obtain the necessary frequency modulation the diode laser was current modulated at ∼ 6 MHz. A noise cancellation circuit was used to suppress detection of the accompanying residual intensity modulation.
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Nest characteristics, breeding dispersal, and nest defence behaviour of Northern Flickers in relation to nest predationFisher, Ryan Jeffrey 28 April 2005 (has links)
I studied nest characteristics, breeding dispersal, and nest defence behaviour of Northern Flickers (<i>Colaptes auratus</i>, hereafter flickers) in central interior British Columbia with respect to nest predation. My research focused on three questions: (1) Are there nest characteristics associated with the risk of nest predation and nest loss to European Starlings (<i>Sturnus vulgaris</i>)? (2) Does nest predation influence breeding dispersal? (3) Do parental attributes influence nest defence behaviour? <p> An examination of flicker nest-site characteristics at five spatial scales revealed that nests were safer from mammalian predators (N=81) when they were higher, concealed by vegetation, farther from continuous coniferous forest blocks, and contained fewer conifers within the nesting clump. Proximity to conifers increased predation risk, but nests safe from competitors (N=18) were closer to coniferous forest blocks and contained a higher percentage of conifers in the nesting clump. Flickers face a trade-off between being safe from predators and safe from competitors. <p> Nesting success did not influence between-year breeding dispersal by 159 male or 76 female flickers. Because nests and forest clumps were not predictably safe from predators, benefits of dispersing likely outweigh costs. Other factors such as mate-switching, nest ectoparasites, and a fluctuating food source may play larger roles in dispersal than nest predation. Within years, 73% of pairs switched nest sites after their first attempt failed due to predation (N=37); however, there was no reproductive advantage for these pairs compared to pairs that remained at their original nest. Stressful encounters with predators involving nest defence may trigger dispersal, although it seems to offer no greater nest success. Of 24 flicker pairs presented with a control model before egg-laying, 3 pairs abandoned their nest, whereas 4 out of 24 pairs presented with a squirrel model abandoned their nest. This suggests that a one-time encounter with a nest predator is not a sufficient deterrent against continued nesting. Rather, costs of finding and excavating or renovating a new cavity may cause individuals to tolerate some risk in nesting at a location with an active predator. <p> In experimental trials (N=94), intensity of nest defence behaviour against a model predator was not related to the sex, age, body size, and body condition of the defending adult(s). The sexes may have behaved similarly because they are similar in size and have similar survival patterns. Costs and benefits of nest defence for flickers of different ages may also be equal because flickers are relatively short-lived and their survival rate is not linked with age. Brood size of the defending adult was also unrelated to the intensity of nest defence. If flickers have adjusted their clutch size in relation to the number of young for which they can optimally provide care, then no effects of brood size on nest defence behaviour should be recorded, as was the case here.</p>
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Individual Trapped Atoms for Cavity QED Quantum Information ApplicationsFortier, Kevin Michael 14 March 2007 (has links)
To utilize a single atom as a quantum bit for a quantum computer requires exquisite
control over the internal and external degrees of freedom. This thesis develops techniques
for controlling the external degrees of freedom of individual atoms. In the first part of
this thesis, individual atoms are trapped and detected non-destructively by the addition of
cooling beams in an optical lattice. This non-destructive imaging technique led to atomic
storage times of two minutes in an optical lattice. The second part of thesis incorporated
the individual atoms into a high finesse cavity. Inside this optical cavity, atoms are cooled
and non-destructively observed for up to 10 seconds.
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The Design and Fabrication of Ring Cavity Semiconductor Laser and FilterChang, Pai-ying 08 July 2004 (has links)
This paper presents design and fabrication of ring cavity semiconductor lasers and optical filters with simple fabrication process. A 1.55
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A Study of Modulation Doped Semiconductor Optical Amplifier and Ring LaserHsueh, Chih-Hsuan 22 July 2005 (has links)
In this thesis, we use InP based multiple quantum well epi-wafer with modulation doping in the active layer to design the semiconductor optical amplifier and ring laser for the optical communication at 1.55£gm wavelength. We also finish the mask design and fabrication of theses two devices. Besides, we have established an optical measurement system, including the L-I measurement, the optical spectrum measurement and the far field measurement, to test the device parameters.
In the device process, we use the new method, called the Multi-Step Undercutting, to precisely control the undercut in the wet etching process. With this technique, we can get a smooth and vertical sidewall for our devices.
For the semiconductor optical amplifier, we design two different types, one is the Fabry-Perot Amplifier and the other is the Traveling Wave Amplifier. We use the Multi-Step Undercutting process in the fabrication of these two devices. The main parameters for semiconductor optical amplifier are the change of the output power versus the input current, the spontaneous emission spectrum and the photocurrent spectrum.
For the ring laser, we combine the concept of Loop Mirror and Asymmetric Mach-Zehnder Interferometer to obtain the laser with good side mode suppression for a single wavelength light source.
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Theoretical analysis of reentrant two-mirror non-planar ring laser cavityTuan, Hung-Tsang 22 November 2005 (has links)
Abstract
In this dissertation a rigorous analysis is performed on the reentrant non-planar ring laser cavity constructed by the Herriott-type multi-pass cell. Since the non-planar ring cavity is a non-orthogonal cavity, so the ABCD matrix method used to analyze the beam propagation is not valid. A rigorous method using Gaussian beam propagation is needed. The beam rotation, astigmatism, and spherical aberration are considered to obtain a self-consistent solution of the Gaussian beam. It turns out that spherical aberration is a very important issue for this non-planar resonator. Without taking into account the spherical aberration, a stable resonator would be difficult to realize. By using a self-consistent Gaussian beam propagation method, the characteristic of laser beam was analyzed and compared with that of the ABCD approximation method.
The reentrant ring cavity is very sensitive to cavity length, especially when the planar and non-planar configurations have the same output beams; therefore, it is very important to consider a rigorous method using Gaussian beam propagation. By considering the coordinate transformation of the beam after mirror reflection, a non-planar figure-8 ring cavity can be treated as an orthogonal cavity except for an exchange of tangential and Sagittal planes after each reflection. A simple astigmatic Gaussian beam approach is used to analyze the non-planar figure-8 ring cavity, and an analytic solution is obtained. For the general case of the multi-pass non-planar ring cavity, a general astigmatic Gaussian beam approach is used to treat the problem. The general form of mirror phase shift is used, and two important differences compared to the ABCD method were found. Firstly, the spot size is always elliptical while the spot size is circular using the ABCD approximation. Secondly, a second stable region is found in the cavity, the width of the second stable region is smaller than the first stable regi
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Fabrication and Measurement of Semiconductor Optical Amplifiers and Ring LasersChen, Jheng-de 10 July 2006 (has links)
In this thesis, we focus on the investigation of semiconductor optical amplifier and ring laser. We use InP based multiple quantum well epi-wafer with modulation doping in the active layer to design the semiconductor optical amplifier and ring laser for the optical communication at 1.55£gm wavelength. We combine the concept of Loop Mirror and Asymmetric Mach-Zehnder Interferometer to obtain the laser with good side mode suppression for a single wavelength light source. For the semiconductor optical amplifier, we design two different types, one is the Fabry-Perot Amplifier and the other is the Traveling Wave Amplifier. Furthermore, We use the Multi-Step Undercutting process in the fabrication of these two devices.
We have established an optical measurement system, including the L-I measurement, the optical spectrum measurement and the far field measurement, to test the device parameters.
After annealing, these devices with two different serial number exhibited the contact resistances of 9£[ and 16£[, respectively. Under CW operation, these FPA exhibited the threshold current of 62mA and 70mA at 20¢J, respectively. The stimulated emission wavelength was at 1531nm and 1522nm, respectively.
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