Dissertation (Ph.D.)--Auburn University,2008. / Abstract. Vita. Includes bibliographic references (p.83-85).

Thesis (Ph. D.)--University of Texas at Austin, 2000. / Vita. Includes bibliographical references (leaves 147-155). Available also in a digital version from Dissertation Abstracts.

Thesis (Ph. D.)--University of Texas at Austin, 2003. / Supervisor: Jack C. Lee. Vita. Includes bibliographical references. Available also from UMI Company.

Thesis (Ph. D.)--University of Texas at Austin, 2000. / Vita. Includes bibliographical references (leaves 101-108). Available also in a digital version from Dissertation Abstracts.

Thesis (Ph. D.)--Institute of Paper Chemistry, 1981. / Includes bibliographical references (p. 67-69).

The research provided in this thesis focuses on the development of high-gain multilayer millimeter-wave (mm-Wave) antenna structures through additive inkjet printing fabrication processes. This work outlines the printing processes of thick dielectric films for use as printed radio frequency (RF) substrates and provides a proof-of-concept demonstration of the first fully-printed RF structures. Using the outlined processes, demonstrations of high-gain mm-Wave proximity-coupled patch array and Yagi-Uda array antennas are presented, achieving the highest realized gain within the 24.5 GHz ISM band for inkjet-printed antennas in literature.

The design and synthesis of new finely tunable porous materials has spurred interest in developing novel uses in a variety of systems. Zeolites, inorganic materials with high thermal and mechanical stability, in particular, have been widely examined for use in applications such as catalysis, ion exchange and separation. A relatively new class of inorganic-organic hybrid materials known as metal-organic frameworks (MOFs) has recently surfaced, and many have exhibited their efficiency in potential applications such as ion exchange and drug delivery. A more recent development is the design and synthesis of a subclass of MOFs based on zeolite topologies (i.e. ZMOFs), which often exhibit traits of both zeolites and MOFs. Bio-compatible hydrogels already play an important role in drug delivery systems, but are often limited by stability issues. Thus, the addition of ZMOFs to hydrogel formulations is expected to enhance the hydrogel mechanical properties, and the ZMOF-hydrogel composites should present improved, symbiotic drug storage and release for delivery applications. Herein we present the novel composites of a hydrogel with a zeolite-like metal-organic framework, rho-ZMOF, using 2-hydroxyethyl methacrylate (HEMA), 2,3-dihydroxypropyl methacrylate (DHPMA), N-vinyl-2-pyrolidinone (VP) and ethylene glycol dimethacrylate (EGDMA), and the corresponding drug release. An ultraviolet (UV) polymerization method is employed to synthesize the hydrogels, VP 0, VP 15, VP 30, VP 45 and the ZMOF-VP 30 composite, by varying the VP content (mol%). The rho-ZMOF, VP 30, and ZMOF-VP 30 composite are all tested for the controlled release of procainamide (protonated, PH), an anti-arrhythmic drug, in phosphate buffer solution (PBS) using UV spectroscopy. Blister agents are chemical compounds that induce severe skin, eye, mucosal pain and irritation. The research focuses on sequestering a blister agent analog, thioanisole in hydrogels. HEMA polymers and copolymers of HEMA with 2,3-dihydroxyproyl methacrylate (DHPMA) and vinyl pyrrolidone (VP) were synthesized with crosslinkers of various dimensions. These were: ethylene glycol dimethacrylate (EGDMA), diethylene glycol dimethacrylate (DiEGDMA), triethylene glycol dimethacrylate (TriEGDMA), tetraethylene glycol dimethacrylate (TetEGDMA) and neopentyl glycol dimethacrylate (NPEGDMA). Equilibrium swelling was characterized gravimetrically and pore size was estimated via scanning electron microscopy (SEM). Glass transition temperatures were measured by differential scanning calorimetry (DSC). The absorption of thioanisole in methanol was characterized with via ultra-violet (UV) spectroscopy. Poly(2-hydroxyethyl methacrylate) (PHEMA) composites constructed from a paddle-wheel, a secondary building unit (SBU) for metal organic frameworks, Cu2(p-OH benzoate)4(DMSO)2*2DMSO (CPW) were also investigated for a broad analysis of dielectric spectra. The dielectric spectrum of poly(2-hydroxyethyl methacrylate) and its copolymer with Poly(2,3-dihydroxy propyl methacrylate) (PDHPMA) are already reported in the literature. This study delineates the effects on the dielectric behavior as a result of CPW addition. The dielectric permittivity and the loss factor were measured using a dielectric analyzer in the frequency range of 1 Hz to 100 k Hz and between the temperature range of -140 and 250°C. The electric modulus formalism was used to reveal the viscoelastic and conductivity relaxations present in the polymers. Significant changes were observed as CPW concentration increased from 0.1 to 0.5 wt%. It was determined through DSC that the glass transition temperature increased with the filler concentration. The secondary dielectric relaxations were also affected as it was recorded that the activation energy for the γ, Β, and conductivity relaxation increased with CPW content. AC and DC conductivity are also evaluated. The ionic conductivity data revealed that the CPW impedes the ion mobility when compared to the neat PHEMA. Organic azides have become a very vital class of chemical compounds in synthetic organic chemistry and in many more fields due to their applications. Azido compounds are considered high-energetic compounds and are studied very little due to their explosive nature. There is an urge to evaluate the thermal stability of this wide variety of compounds which have tremendous applications in synthetic as well as organic chemistry. Here in we report the thermal stability of some organic azides such as sulfonyl, phosphoryl and carbonyl azides using differential scanning calorimetry (DSC) as an evaluating tool. Initial temperature of decomposition (Ti) and temperature of maximum decomposition (Tmax) are recorded. The area under exotherm peak during decomposition is used to determine the energy of decomposition (Ed) and is compared to threshold value for hazardous/explosive compounds. The effect of substituent groups at different positions, nature of the substituent groups (electron donating or electron withdrawing) and the steric hindrance on the thermal stability of these azides is studied in detail to verify the explosive nature of these compounds.

With the emergence of Matrix Assisted Laser Desorption/Ionization-Time-of-flight as a tool for diagnosis of diseases via proteomics, there is an increasing need for greater sensitivity. Analysis of peptides by MALDI-TOF-MS is affected by sample formulation and spotting onto a MALDI target. This dissertation investigates a novel MALDI sample preparation technique, Induction Based Fluidics (IBF), for depositing precise volumes (pL to nL) of samples onto the target. We have seen that while using IBF, the induced electric field accompanying deposition enhances matrix crystallization yielding smaller crystals with more homogeneity, as compared to conventional manual micropipette (MP) depositions. An investigation of the signal-to-noise (S/N) for IBF deposition of tryptic digested Bovine Serum Albumin (BSA) showed a significant improvement in the signal-to-noise ratio for 0.5 and 0.25 pmol/µL BSA sample compared to equivalent MP depositions. The S/N enhancement for IBF and MP depositions of BSA were studied using à-cyano-4-hydroycinnamic acid (CHCA) and 2,5-dihydroxybenzoic acid (DHB) matrices, and CHCA showed better results than DHB . The exciting results obtained by IBF prompted us to probe sample morphology more fully and to relate morphology to the detections level and hopefully, to increase the utility of MALDI-TOF-MS for detection of a larger range of peptides. Morphology results were correlated to sensitivity limits using both dispensing techniques. Because of dissimilar rates of evaporation, different or uneven deposition thickness, or crystal lattice morphology, discontinuous crystallization patterns were observed for MP depositions. However, IBF deposited samples occupied less planar area with uniform distribution of crystals, thereby reducing sample crystal heterogeneity and laborious hunt for a "sweet" or "hot" spot to produce high quality spectra. The application of IBF was extended to the tryptic digested BSA protein using peptide mass fingerprinting. IBF deposition resulted in a larger number of detectable peptides as well as higher sequence coverage as compared to equivalent MP depositions. In last few decades, advanced research and potential applications in the field of microelectronics have spurred interest in the development of reticulated doped polymer films. Bis (ethylenedioxy) tetrathiafulvalene (BEDO-TTF)/Polycarbonate (PC) films were synthesized and characterized for use in hand-held real time explosives sensors, capable of detecting nitro-based compounds (nitroaromatics, nitoamines and nitroesters), which are the main components of Improvised Explosive Devices or IEDs. Reticulated doped polymer films were prepared by exposing solid solutions of BEDO-TTF in PC to iodine to form conductive charge transfer complexes. The resulting films exhibited room temperature conductivities ranging from 6.33-90.4*10-5 S cm-1. The colored iodine complexes in the film were reduced by cyclic voltammetry yielding conductive, colorless, transparent films. Dielectric analysis (DEA) was used to probe relaxations in neat PC and BEDO-TTF/PC showed that BEDO-TTF plasticized the PC and decreased the glass transition temperature. Two secondary relaxations appeared in PC films, whereas the transitions merged in the doped film. DEA also revealed conductivity relaxations above 180°C, which were characterized by the electric modulus formalism and showed that BEDO-TTF increased the alternating current, (AC) conductivity in PC.

The continual downscaling of the thickness of the SiO₂ layer in the complementary metal oxide semiconductor (CMOS) transistors has been one of the main driving forces behind the growth of the semiconductor industry for past 20-30 years. The gate dielectric works as a capacitor and therefore the reduction in thickness results in increase of capacitance and the speed of the device. However, this process has reached the limit when the further reduction of the SiO₂ thickness will result in a leakage current above the acceptable limit, especially for mobile devices. This problem can be resolved by replacing SiO₂ with materials which have higher dielectric constants (high-k). The leading candidates to replace SiO₂ as a gate material are hafnium dioxide and hafnium silicate. However, several problems arise when using these materials in the device. One of them is to find p and n type gate metals to match with the valence and conduction band edges of silicon. This problem can be rooted in lack of our understanding of the band alignment and its controlling mechanisms between the materials in the gate stack. Theoretical simulations using density functional theory can be very useful to address such problems. In this dissertation present a theoretical study of the band alignment between HfO₂ and SiO₂ interface. We identify oxygen coordination as a governing factor for the band alignment. Next, we discuss effects of Al incorporation on the band alignment at the SiO₂/HfO₂ interface. We find that one can tune the band alignment by controlling the concentration of Al atoms in the stack. We also perform a theoretical study of HfO₂/Metal interface in case of Rh. We identify Rh as a good candidate for a p-type gate metal due to its large work-function and the low oxidation energy. Finally, we report a study of the stability of oxygen vacancies across the gate stack. We model a gate stack composed of n-Si/SiO₂/HO₂/Rh. We find that oxygen vacancies are easier to create in SiO₂ than in HfO₂. Also, vacancies in HfO₂ modify the band alignment, while in SiO₂ they have no effect. / text

In order to address the challenges of capacitive sensing in harsh environment, self resonant passive wireless sensors are studied. The capacitive sensing elements based on interdigitated capacitor (IDC) sensor are used. A semi-empirical model providing accurate capacitance calculation for IDCs over a wide range of dimensions and dielectric constants is developed. An equivalent circuit model based on electric field distribution is proposed, leading to a closed form approximation for IDC capacitance calculation. The conductivity of the material under test is also considered and a model is proposed to calculate effective capacitance as a function of conductivity and measurement frequency. The model is used to study the design optimization of IDC sensor and suggested design procedure is proposed. To wirelessly interrogate the capacitive sensor, it is connected to an inductive element to form a resonant circuit, while the measurement is made at remote reader coil. Advantages and disadvantages of different type of resonant structure design are analyzed. In order to assist the design process, a SPICE circuit model is developed to estimate the resonant frequency of the self resonant sensor. Miniaturized sensors with different dimensions are designed, fabricated and tested. The sensor is integrated with silicon nanowire fabric coated with polymer. Measurements are made to illustrate the enhancement in sensing capability by integrating chemical selective material. / text