Now showing items 14612-14631 of 39116

    • F-spin study of rare earth nuclei using F-spin multiplets and angular momentum projected intrinsic states.

      Diallo, Abdoulaye Foula.; Barrett, Bruce R.; Kohler, Sigurd; Garcia, J.D.; Donahue, Douglas J.; McIntyre, Laurence C. (The University of Arizona., 1993)
      The proton-neutron Interacting-Boson Model contains both symmetric and mixed-symmetry proton-neutron boson configurations. These states of different proton-neutron symmetry can be classified in terms of an SU(2) symmetry, called F-spin. This dissertation deals with some new applications of F-spin. Even-even nuclei drawn from the proton and neutron shells 50 < Z < 82 and 82 < N < 126, respectively, are systematically classified in F-spin multiplets and their binding energies are fit with a six-parameter mass-formula. Using particle-hole symmetry conjugation, the energies of the low-lying levels of the neutron-rich nuclei are estimated and their mass excesses determined with the mass-formula. The masses of these nuclei are of interest in astrophysical processes. A novel asymptotic realization of the angular-momentum projected intrinsic-state in the generalized IBM is presented. This approach which uses the Laplace method of asymptotic expansion, is shown to be an improvement over the Gaussian method espoused by Kuyucak and Morrison. The method, herein called the 1/Λ-expansion, is used to derive analytical expressions for different quantities in the framework of the generalized IBM. Particular attention is paid to the M1 summed strength, the mean-excitation energy of the mixed symmetry 1⁺ scissor mode, and the gyromagnetic ratios of the ground-band members, for which formulas are derived. A no-free-parameter calculation is performed for the summed M1 strength and the centroid energy of ⁽¹⁴⁶⁻¹⁵⁸⁾Sm isotopes. The g factors of deformed and transitional nuclei in the rare-earth mass region are also computed. The data in all cases are found to be well reproduced, in general. A weak L dependence is predicted for the g factors, and there appears to be no need to include two-body terms in the T(M1) operator for determining the M1 strength.
    • F.I.T. Fitness Innovation Tools: The All-In-One Digital Fitness Tool

      Gardon, Tyler Andrew; Rutledge, Cat; Heinlein, Taylor; Diaz, Andres (The University of Arizona., 2011-05)
    • F.I.T.: Fitness Innovation Tools Business Plan

      Rutledge, Caitlyn Michele; Gardon, Tyler; Heinlein, Taylor; Diaz, Andres (The University of Arizona., 2011-05)
    • The F.O.B. cost of marketing desert citrus fruit

      Dobbins, C. E. (Claude Edwin), 1917- (The University of Arizona., 1949)
    • THE FABLIAUX AND THE NATURALISTIC TRADITION

      Laughlin, Virginia Lillian, 1924- (The University of Arizona., 1972)
    • FABRIC CHANGES ACCOMPANYING SHEAR STRAINS IN A COHESIVE SOIL

      Nowatzki, Edward Alexander, 1936- (The University of Arizona., 1966)
    • Fabrication and Application of Absorption-Based and Interference-Based Micropolarizers

      Pau, Stanley; Hsu, Wei-Liang; Pau, Stanley; Liang, Rongguang; Chipman, Russell (The University of Arizona., 2014)
      The ability to create arbitrary patterned linear, circular, and elliptical liquid crystal polymer polarizers is demonstrated in this work. The operating wavelength of the thin-film polarizer ranges from 400 to 4200 nm. The linear absorption-based micropolarizer is fabricated using dichroic dye as a guest in liquid crystal polymer host with feature sizes as small as 4 µm. The circular interference-based micropolarizer is fabricated using cholesteric liquid crystal polymers with feature sizes as small as 6.2 µm. The elliptical micropolarizer is achieved using the combination of a microretarder and a micropolarizer. The chemistry, fabrication process, spatial resolution and optical properties of micropolarizers are presented. Alignments of liquid crystal polymers and cholesteric liquid crystal polymers are both achieved using photoalignment technique with polarized photo-lithography. Two different methods, thermal annealing and solvent rinse, are utilized for patterning cholesteric liquid crystal polymers over large areas. In addition to exploring absorption-based and interference-based micropolarizers, arrays of micropolarizers are fabricated for the construction of 580nm and 760nm division-of-focal-plane full-Stokes imaging polarimeters. The polarimeter utilizes a set of four optimized measurements which represent a regular tetrahedron inscribed in the Poincaré sphere. Results from the device fabrication, instrument calibration and characterization for the 580 nm polarimeter are presented. The optimized imaging polarimeter can be used for sampling the polarization signature across a scene with a resolution of 1608 x 1208 x 14-bit at 20 frames/second.
    • Fabrication and characterization of erbium doped waveguide amplifiers and lasers

      Peyghambarian, Nasser; Madasamy, Pratheepan (The University of Arizona., 2003)
      Planar waveguide amplifiers and lasers were fabricated using Ag film ion exchange on Er³⁺/Yb³⁺ codoped phosphate glass. The performance of these amplifiers and lasers were studied and characterized. Silver film ion exchange process was thoroughly studied and a process suitable for fabrication of low loss waveguides on Er³⁺/Yb³⁺ codoped phosphate glass was developed. A transmission loss of 0.15 dB/cm was obtained in surface waveguides on phosphate glass. Planar waveguide amplifiers were fabricated on Er³⁺/Yb³⁺ codoped phosphate glass and characterized. A net gain of 7 dB in a sample of length 4.7 cm and gain/cm of 1.5 dB/cm were achieved. Single mode waveguide laser arrays pumped by single mode laser diodes were fabricated. Their performance was characterized in terms of the output power, spectrum of the laser, lasing wavelength dependence on the waveguide width and the relative intensity noise (RIN) of the laser. The tunability of the lasing wavelength to the desired wavelength, after waveguide fabrication, by annealing was demonstrated. A novel planar waveguide laser configuration for single-mode operation around 1550 nm using cost-effective multimode diode pumping was demonstrated. The laser was fabricated by Ag film ion exchange in a hybrid phosphate glass which has active and passive regions monolithically integrated in a single glass chip. Power of 54 mW at 1538 nm was measured from the single-mode output waveguide.
    • Fabrication and Characterization of Recombinant Silk-elastinlike Protein Fibers for Tissue Engineering Applications

      Wu, Xiaoyi; Qiu, Weiguo; Wong, Pak Kin; Yoon, Jeong-Yeol; Zohar, Yitshak; Wu, Xiaoyi (The University of Arizona., 2011)
      The integration of functional and structural properties makes genetically engineered proteins appealing in tissue engineering. Silk-elastinlike proteins (SELPs), containing tandemly repeated polypeptide sequence derived from natural silk and elastin, are recently under active study due to the interesting structure. The biological, chemical, physical properties of SELPs have been extensively investigated for their possible applications in drug/gene delivery, surgical tissue sealing and spine repair surgery. However, the mechanical aspect has rarely been looked into. Moreover, many other biomaterials have been fabricated into fibers in micrometer and nanometer scale to build extracellular matrix-mimic scaffolds for tissue regeneration, but many have one or mixed defects such as: poor strength, mild toxicity or immune repulsion etc. The SELP fibers, with the intrinsic primary structures, have novel mechanical properties that can make them defects-minimized scaffolds in tissue engineering.In this study, one SELP (SELP-47K) was fabricated into microfibers and nanofibers by the techniques of wet-spinning and electrospinning. Microfibers of meters long were formed and collected from a methanol coagulation bath, and later were crosslinked by glutaraldehyde (GTA) vapor. The resultant microfibers displayed higher tensile strength up to 20 MPa and higher deformability as high as 700% when tested in hydrated state. Electrospinnig of SELP-47K in formic acid and water resulted in rod-like and ribbon-like nanofibrous scaffolds correspondingly. Both chemical (methanol and/or GTA) and physical (autoclaving) crosslinking methods were utilized to stabilize the scaffolds. The chemical crosslinked hydrated scaffolds exhibit elastic moduli of 3.4-13.2 MPa, ultimate tensile strength of 5.7-13.5 MPa, and deformability of 100-130%, closely matching or exceeding the native aortic elastin; while the autoclaved one had lower numbers: 1.0 MPa elastic modulus, 0.3 MPa ultimate strength and 29% deformation. However, the resilience was all above 80%, beyond the aortic elastin, which is 77%. Additionally, Fourier transform infrared spectra showed clear secondary structure transition after crosslinking, explaining the phenomenon of scaffold water-insolubility from structural perspective and showed a direct relationship with the mechanical performance. Furthermore, the in vitro biocompatibility of SELP-47K nanofibrous scaffolds were verified through the culture of NIH 3T3 mouse embryonic fibroblast cells.
    • Fabrication and characterization of variable groove depth grating waveguide couplers.

      Bates, Allen Keith.; Burke, James J.; Lawrence, George N.; Li, Lifeng (The University of Arizona., 1994)
      Variable groove depth grating waveguide couplers (VGDGWCs) can be used to couple light into or out of planar waveguides. In principle an out-coupled light beam with any arbitrary irradiance profile can be obtained. VGDGWCs that produce out-coupled beams exhibiting a Gaussian irradiance profile are examined in this report. An expression for the grating groove depth variation necessary to produce Gaussian beams from VGDGWCs is derived. The design of a VGDGWC using two different materials for the host planar waveguide is presented. The designs are optimized with a consideration of the waveguide materials, the fabrication process, and the out-coupled beam quality. Two methods, that utilize ion etching to fabricate VGDGWCs are presented. Each method operates by limiting the cross sectional area of an ion beam. A scanning slit is used for one method and a moving variable width aperture is employed for the second. The ion etching process for each of the fabrication methods is characterized by a series of ion beam etching experiments. The results from the ion beam etching experiments are used to optimize the fabrication process. The variable width aperture fabrication method in combination with a post etching process, is found to produce the optimum results. The measured irradiance profile and the wavefront quality of the out-coupled beams from the fabricated VGDGWCs are compared to theory. The variable width aperture fabrication method is found to produce out-coupled beams with a nearly perfect Gaussian irradiance profile. The measured wavefront quality of out-coupled beams shows good agreement with theory.
    • Fabrication and investigation of GaAsP light emitting diodes

      Salzman, James Donald, 1931- (The University of Arizona., 1972)
    • Fabrication and modeling of a floating-gate transistor for use as an electrostatic-discharge detector

      Schrimpf, Ron D.; Hsueh, Weichung Paul, 1962- (The University of Arizona., 1988)
      Electrostatic discharge is of great concern to the electronics industry. It degrades and destroys large numbers of integrated circuits at every step from fabrication through packaging and testing. The goal of this research effort was the development of a device that can be used to obtain quantitative information on electrostatic discharge (ESD) in the integrated-circuit workplace. The device that was developed can be utilized in two different modes. (1) It can be used to form ESD test wafers or test chips. (2) It can be incorporated on product chips to give the ESD history of devices or monitor the process line. The technology that was examined in this work was that for floating-gate PROMS. A simple analytical model for obtaining a parameter called the ESD factor was developed. The prototype detector was designed, fabricated and tested in the Semiconductor Processing Facility of the University of Arizona. Evidence will be presented that the FLOTOX type of EEPROM functions well in its application as an ESD detector.
    • Fabrication and structural, optical, and electrical characterization of multisource evaporated copper-gallium-selenide polycrystalline thin films.

      Risbud, Subhash; Albin, David Scott.; Demer, Louis; Lynch, David C.; Hamilton, Douglas J; O'Hanlon, John (The University of Arizona., 1989)
      Theoretical considerations for the use of chalcopyrite ternary I-III-VI₂ compounds in heterojunction photovoltaic conversion devices are presented, followed by an in-depth study of the structural, optical, and electrical characteristics of multi-source evaporated CuGaSe₂ thin films as determined by processing. Film composition was identified as the primary variable for affecting the microstructure and optical-electrical behavior of the films. Film composition was in turn dependent upon elemental flux rates and substrate related effects. Films deposited on glass and bare alumina substrates were richer in selenium than films deposited on molybdenum coated substrates. Cu-poor, near stoichiometeric, and Cu-rich compositions were obtained by varying the Cu/Ga flux ratio. Cu-poor films deposited on bare ceramic substrates were characterized by secondary impurity phase content and a tendency for cubic CuGaSe₂ formation. The cubic nature of optically thin films deposited on glass was substantiated by a lack of crystal field splitting of the valence band as observed by optical absorption measurements. Cubic-tetragonal phase behavior was monitored on optically opaque samples by observation of intensity-independent (112)/(111) x-ray diffraction peak shifts. Cu-poor films on glass were also characterized by surfaces pitting at substrate temperatures in excess of 450°C which may be related to the high surface energy of gallium. Cu-poor films deposited on molybdenum coated alumina substrates exhibited less impurity phase formation and were largely single-phase tetragonal CuGaSe₂. Cu-rich films on all substrates contained CuₓSe impurities and tetragonal CuGaSe₂.
    • FABRICATION AND TESTING OF A SENSITIVE ULTRAVIOLET-VISIBLE SILICON PHOTODIODE DEVICE

      Martínez Montes, José de la Luz (The University of Arizona., 1979)
    • Fabrication of a micro-Fresnel lens on a spherical substrate

      Milster, Thomas D.; Trusty, Robert Mason, 1959- (The University of Arizona., 1990)
      A decrease in the size and weight of the objective lens in an optical data storage system (ODS) would improve performance. Limits on reducing the lens size were investigated. Size reduction is limited by aberrations introduced by the disk cover plate that protects the recording medium from dust and scratches. Size reduction is also limited by off-axis aberrations introduced by beam tilt required to maintain a field of view similar to conventional ODS objectives. It was shown that a Fresnel microlens on a thin spherical shell is acomatic for all field angles. A technique used to fabricate such a lens was demonstrated. The resulting lens was presented.
    • Fabrication of low-loss planar waveguides and development of integrated optical chemical sensors

      Armstrong, Neil R.; Yang, Lin, 1963- (The University of Arizona., 1996)
      Applications of planar integrated optical waveguide (IOW) technology to problems in surface spectroscopy and optical chemical sensing have been partly limited by the difficulty of producing high quality glass IOWs is. The fabrication of IOWs by the sol-gel method from methyltriethoxysilane and titanium tetrabutoxide precursors has therefore been developed. The physical, chemical, and optical properties of the films were studied using a variety of analytical techniques. The results show that the catalyst used to accelerate the sol-gel reaction strongly influenced the optical quality of the IOW. A novel optical sensing platform was subsequently developed using a sol-gel derived, laminate planar IOW structure. The sensing element is fabricated by coating a sol-gel IOW with a second, porous sol-gel layer in which optical indicator molecules are physically entrapped, yet remain sterically accessible to analytes that diffuse into the pore network. Formation of a complex between the analyte and entrapped indicator is detected via attenuated total reflection (ATR) of light guided in the IOW. Feasibility was evaluated by constructing IOW-ATR sensors for Pb2+ and pH, based on entrapped xylenol orange and bromocresol purple respectively. The response of both sensors was sensitive and rapid. This work was further extended to the development of a new class of gaseous iodine sensors. The sensing principle is based on the detection of a charge transfer complex formed between iodine and phenyl groups that have been incorporated into a porous, methylated glass film. The sol-gel iodine sensor exhibits a linear response to gaseous I2 in the range of 100 ppb to 15 ppm with response and recovery times less than 15 sec. Langmuir-Blodgett (LB) films have also been deposited on a sol-gel IOW from zinc 1,4,8,11,15,18,22,25-octabutoxy-phthalocyanine (ZnPc). Planar waveguide linear dichroism was used to determine molecular orientation in a ZnPc LB monolayer. The IOW-supported ZnPc monolayer was found to exhibit a sensitive spectral response to gaseous I2. The overall optical sensing approach described in this dissertation is technically simple, inexpensive, and applicable to a wide variety of chemical sensing problems.
    • Fabrication of micro-optics using binary and graylevel masks

      Descour, Michael; Simon, Daniel I, 1971- (The University of Arizona., 1998)
      This thesis provides step by step instructions on how to design, layout, and fabricate diffractive optical elements (DOE). While there has been a great deal published on the design of DOEs, there are few publications detailing how to transform a design into a physical element. The thesis describes how to order a photomask and pattern an element. It provides recipes that I have used to etch DOEs with both an ion mill and a reactive ion etcher (RIE) at the Optical Sciences Center. The thesis includes characterization of the elements fabricated using these recipes. In addition the thesis looks at the design and fabrication of ring toric lenslets. A ring toric lenslet is a DOE that focuses light to a ring instead of a point. The ring toric lenslet has potential applications in the optical data storage industry. This thesis includes macros for the design and mask layout of binary and grayscale ring toric lenslets. Grayscale elements require special design, calibration, and mask layout steps not necessary for binary elements. Details of the design, calibration, mask layout, and fabrication of the grayscale element are included.
    • Fabrication of Multimodal Organic-Inorganic Hybrid Nanovesicles and Study on their Intracellular Fates in Cancer Cells by Single Particle Tracking

      Wu, Xiaoyi; Leung, Siu Ling; Wu, Xiaoyi; Enikov, Eniko T.; Zohar, Yitshak; Romanowski, Marek (The University of Arizona., 2013)
      Creation of magic bullets might be the dream of all scientists working on anticancer therapeutics. In reality, there are always pros and cons. Chemotherapeutics such as doxorubicin and paclitaxel can effectively inhibit growth of cancer cells; however, the drugs at a high dosage are not selective and can cause severe damage to normal tissues and/or organs. To minimize its side effects, anticancer therapeutics are often encapsulated using nanovesicles (NVs). Antibodies that target specific cancer cells may be conjugated with drug-carrying NVs to further improve the selectivity of drug delivery. In the design and fabrication of NV-based drug carriers, many structural and micro-environmental factors affect cellular uptake and internalization of drug-carrying NVs, drug release and distribution in tissues, and therapeutic efficiency. Two goals of my dissertation study is (1) to fabricate multimodal NVs for bio-imaging, selective targeting and drug delivery and (2) to unfold interplays between different factors and intracellular fates of these NVs in prostate cancer cells. This proposed work separates into four phases: (1) Novel organic-inorganic liposomal cerasomes will be used as drug carriers for delivery of potent anticancer doxorcubicin (DOX). Liposomes will be stabilized via an addition of inorganic polyorganosiloxane networks on their surfaces, creating liposomal cerasomes, and its potential to store and release DOX will be investigated. (2) Prostate cancer cells will be used as a model system to study endocytic pathway of cerasomes. Among various types of human cancer, prostate cancer is the second leading cause of death for man. It is anticipated that the proposed study will shed new insights into endocytosis drug-carrying NVs. Results from the study may facilitate the development of cerasome-based therapeutics for treating prostate cancer patients. (3) Since diagnostic, imaging and therapy are three major biomedical applications in nanotechnology, multifunctional NVs with combined bio-imaging, therapeutic efficiency and selective targeting modalities are essential as next-generation nano-carriers. Here, we proposed to incooperate fluorophores and prostate cancer targeted antibodies into cerasomes to achieve our multimodal NVs. (4) Single particle tracking (SPT) analysis will be used to study the intracellular fates of cerasome uptake in single cell level. SPT is an advanced imaging technique permits the real-time monitoring of cellular entry, intracellular transport and internalization of multiple NVs. Our main focus is to identify the different in cellular transportation mechanism between targeted and non-targeted vesicles. Moreover, SPT will be integrated into a microfluidic system, which not only minimizes the consumption of reagents/ materials but also allows us to precisely control biochemical environments around cells.
    • Fabrication of Novel Structures to Enhance the Performance of Microwave, Millimeter Wave and Optical Radiators

      Ziolkowski, Richard W.; Gbele, Kokou; Dvorak, Steven L.; Tyo, Scott J.; Ziolkowski, Richard W. (The University of Arizona., 2016)
      This dissertation has three parts which are distinctive from the perspective of their frequency regime of operation and from the nature of their contributions to the science and engineering communities. The first part describes work that was conducted on a vertical-external-cavity surface emitting-laser (VECSEL) in the optical frequency regime. We designed, fabricated, and tested a hybrid distributed Bragg reflector (DBR) mirror for a VECSEL sub-cavity operating at the laser emission wavelength of 1057 nm. The DBR mirror was terminated with a highly reflecting gold surface and integrated with an engineered pattern of titanium. This hybrid mirror achieved a reduction in half of the number of DBR layer pairs in comparison to a previously reported, successful VECSEL chip. Moreover, the output power of our VECSEL chip was measured to be beyond 4.0Wwith an optical-to-optical efficiency of 19.4%. Excellent power output stability was demonstrated; a steady 1.0 W output at 15.0 W pump power was measured for over an hour. The second part reports on an ultrafast in situ pump-probing of the nonequlibrium dynamics of the gain medium of a VECSEL under mode-locked conditions. We proposed and successfully tested a novel approach to measure the response of the inverted carriers in the active region of a VECSEL device while it was operating under passively mode-locked conditions. We employed the dual-frequency-comb spectroscopy (DFCS) technique using an asynchronous optical sampling (ASOPS) method based on modified time-domain spectroscopy (TDS) to measure the nonequilibrium dynamics of the gain medium of a phase-locked VECSEL that we designed and fabricated to operate at the1030 nm emission wavelength. Our spectroscopic studies used a probe pulse of 100 fs and an in situ pump pulse of 13 ps. We probed the gain medium of the VECSEL and recorded a depletion time of 13 ps, a fast recovery period of 17 ps, and 110 ps for the slow recovery time. Our scans thus demonstrated a 140 ps full depletion-recovery cycle in the nonequilibrium state. The third part discusses work in the microwave and millimeter wave frequency regimes. A new method to fabricate Luneburg lenses was proposed and demonstrated. This type of lens is well known; it is versatile and has been used for many applications, including high power radars, satellite communications, and remote sensing systems. Because the fabrication of such a lens requires intricate and time consuming processes, we demonstrated the design, fabrication and testing of a Luneburg lens prototype using a 3-D printing rapid prototyping technique both at the X and Ka-V frequency bands. The measured results were in very good agreement with their simulated values. The fabricated X-band lens had a 12 cm diameter and produced a beam having a maximum gain of 20 dB and a beam directivity (half-power beam width (HPBW)) ranging from 12° to 19°). The corresponding Ka-V band lens had a 7 cm diameter; it produced a beam with a HPBW about the same as the X-band lens, but with a maximum gain of more than 20 dB.
    • Fabrication of Polystyrene Core-Silica Shell Nanoparticles for Scintillation Proximity Assay (SPA) Biosensors

      Aspinwall, Craig A.; Noviana, Eka; Heien, Michael L.; Pyun, Jeffrey (The University of Arizona., 2015)
      The development of analytical tools for investigating biological pathways on the molecular level has provided insight into diseases and disorders. However, many biological analytes such as glucose and inositol phosphate(s) lack the optical or electrochemical properties needed for detection, making molecular sensing challenging. Scintillation proximity assay (SPA) does not require analytes to possess such properties. SPA uses radioisotopes to monitor the binding of analytes to SPA beads. The beads contain scintillants that emit light when the radiolabeled analytes are in close proximity. This technique is rapid, sensitive and separation-free. Conventional SPA beads, however, are large relative to the cells and made of hydrophobic organic polymers that tend to aggregate or inorganic crystals that sediment rapidly in aqueous solution, thus limiting SPA applications. To overcome these problems, polystyrene core-silica shell nanoparticles (NPs) doped with pTP and dimethyl POPOP were fabricated to produce scintillation NPs that emit photons in the blue region of visible light. The developed scintillation particles are approximately 250 nm in diameter (i.e. 200 nm of core diameter and 10-30 nm of shell thickness), responsive to β-decay from tritium (³H) and have sufficient stability in the aqueous media. DNA hybridization-based SPA was performed to determine whether the scintillation NPs could be utilized for SPA applications. A 30-mer oligonucleotide was immobilized on the polystyrene core-silica shell NPs to give approximately 7.6 x 10³ oligonucleotide molecules per NP and ³H-labeled complementary strand was annealed to the immobilized strand. At the saturation point, increases in scintillation signal due to oligonucleotide binding to the NPs were about 9 fold compared to the control experiments in which no specific binding occurred, demonstrating that the scintillation NPs can be utilized for SPA. Along with the improved physical properties including smaller size and better stability in the aqueous system, the developed scintillation NPs could be potentially useful as biosensors in cellular studies.