Orientador: Marli Terezinha Cassamassimo Duarte / Resumo: As úlceras cutâneas crônicas de origem neuropática secundárias à hanseníase são de difícil resolução e onerosas ao sistema público de saúde e aos pacientes acometidos. Há coberturas de alta tecnologia para o tratamento das úlceras, entretanto, são de custo elevado. Desta forma, faz-se necessário identificar tratamento que possa ser usado nessa população, buscando minimizar ou regredir completamente a úlcera e que seja de baixo custo. Objetivo: Avaliar a viabilidade de um protocolo para uso da pomada de óxido de zinco nas concentrações a 20% e 25% comparada ao hidrogel, no tratamento de úlcera crônica de perna de pessoas com sequelas de hanseníase e propor instrumento de acompanhamento de pacientes em tratamento de úlceras crônicas. Método: Estudo clínico pragmático, do tipo piloto, randomizado com três braços paralelos, aberto em relação ao controle (hidrogel) e cego entre os dois grupos de intervenção, a saber: óxido de zinco a 20% e 25%. A população do estudo foi constituída por pacientes atendidos nos ambulatórios do Instituto Lauro de Souza Lima, portadores de úlceras de perna, que já concluíram o tratamento para a hanseníase e a amostra constituída por 12 pacientes com 36 úlceras. Como desfechos primários foram avaliadas as taxas de adesão, recrutamento e de eventos adversos. O desfecho secundário foi a avaliação da eficácia das intervenções por meio da avaliação inicial e evolução da úlcera, empregando-se a Pressure Ulcer Scale for Healing (PUSH) e a mediana da área em ... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The chronic skin ulcers of neuropathic origin, secondary to leprosy, are difficult to heal and costly to the public health system and patients. There are high technology dressings for wound treatment, however, they are expensive. In this way, it is necessary to identify the treatment which can be applied to this population, seeking to minimize or completely reduce the ulcer at lower costs. Objective: To evaluate the viability of a protocol for the use of zinc oxide ointment at 20% and 25% concentrations compared to hydrogel, in the treatment of chronic leg ulcers of people with leprosy sequelae, and to suggest a follow-up instrument for patients under treatment of chronic ulcers. Method: This is a pragmatic, pilottype, randomized trial with three parallel segments, open to the control (hydrogel) and blind between the two intervention groups, namely: zinc oxide at 20 and 25%. The study population consisted of patients with leg ulcers, attended at the outpatient clinics of Lauro de Souza Lima Institute, who had already completed the treatment for leprosy, and the sample comprised 12 patients with 36 ulcers. Adherence, recruitment, and adverse event rates were assessed as primary outcomes. Evaluation of the efficacy of the interventions through the initial evaluation and evolution of the ulcer, using Pressure Ulcer Scale for Healing (PUSH), and median of the area in cm2, were assessed as secondary outcomes. Results: Four participants with 11 ulcers were included in the hydrogel ... (Complete abstract click electronic access below) / Mestre

Uniformly distributed ZnO nanorods with diameter 70-100 nm and 1-2μm long have been successfully grown at low temperatures on GaN by using the inexpensive aqueous solution method. The formation of the ZnO nanorods and the growth parameters are controlled by reactant concentration, temperature and pH. No catalyst is required. The XRD studies show that the ZnO nanorods are single crystals and that they grow along the c axis of the crystal plane. The room temperature photoluminescence measurements have shown ultraviolet peaks at 388nm with high intensity, which are comparable to those found in high quality ZnO films. The mechanism of the nanorod growth in the aqueous solution is proposed. The dependence of the ZnO nanorods on the growth parameters was also investigated. While changing the growth temperature from 60°C to 150°C, the morphology of the ZnO nanorods changed from sharp tip (needle shape) to flat tip (rod shape). These kinds of structure are useful in laser and field emission application. / Singapore-MIT Alliance (SMA)

Im Rahmen der vorliegenden Arbeit wurden Zinkoxid (ZnO)-basierte Metal-Isolator-Halbleiter Feldeffekttransistoren (MISFETs) mit Wolframtrioxid als transparentes Dielektrikum untersucht. Im ersten Teil werden die morphologischen, optischen, elektrischen und chemischen Eigenschaften der mittels gepulster Laserabscheidung (PLD) gewachsenen Wolframoxiddünnfilme, in Abhängigkeit vom Züchtungsdruck, diskutiert. Mit Hilfe dieser Ergebnisse konnte schließlich das hochisolierende Wolframtrioxid erfolgreich mit einer transparenten Gateelektrode, bestehend aus dem entarteten Halbleiter Zink-Galliumoxid (ZGO) bzw. Zink-Aluminiumoxid (AZO), kombiniert und somit MISFETs auf kristallinen und amorphen Substraten realisiert werden. Zur Optimierung der Transistoreigenschaften wurde die Dicke des Dielektrikums variiert und der Einfluss auf die Transfereigenschaften diskutiert. Des Weiteren wurde zur Verschiebung der Einschaltspannung eine Variation der Kanaldicke und des Elektrodenmaterials des Gates untersucht, wodurch die Möglichkeit der Herstellung von Verarmungs- bzw. Anreicherungstyptransistoren gegeben wurde. Um einen Vergleich der Transfereigenschaften des MISFETs gegenüber einem Metall-Halbleiter Feldeffekttransistor mit einem Schottky-Gatekontakt, bestehend aus oxidiertem Platin bzw. einem Sperrschicht-Feldeffekttransistor mit Zinkkobaltit als p-dotierten Bereich zu ermöglichen, wurden alle drei Transistorarten auf einem Substrat hergestellt und umfassend verglichen. Schließlich wird die Stabilität der Transistoren untersucht. Dabei wird der Einfluss einer permanenten Spannungsbelastung auf die Transfereigenschaften unter verschiedenen einflussnehmenden Bedingungen diskutiert. Abschließend werden aufgrund einer sich ausbildenden Hysterese der Transistoreigenschaften mögliche Ursachen derselben und Wege zur Passivierung der Bauelemente untersucht.

Purpose: This retrospective study was performed to assess the clinical and radiographic success rates of a non-vital formocresol and zinc oxide eugenol (ZOE) primary molar root canal therapy (RCT) technique. The effects of this treatment on the permanent successors and on exfoliation times were also investigated. Methods: The study included 161 patients with 211 primary molars treated by RCT by a single operator in a private pediatric dental office in the Toronto area. Results: A clinical success rate of 90.0% and a radiographic success rate of 77.3% were obtained. Enamel defects were found in 6.8% of permanent successors and in patients who were significantly younger at the time of root canal therapy treatment (p = .001). Treated molars exfoliated on average 5.8 months sooner than contralateral teeth (p<0.001). Conclusions: Formocresol and ZOE RCT is a viable treatment for necrotic primary molars and yielded very high clinical success rates with moderate radiographic success rates.

Purpose: This retrospective study was performed to assess the clinical and radiographic success rates of a non-vital formocresol and zinc oxide eugenol (ZOE) primary molar root canal therapy (RCT) technique. The effects of this treatment on the permanent successors and on exfoliation times were also investigated. Methods: The study included 161 patients with 211 primary molars treated by RCT by a single operator in a private pediatric dental office in the Toronto area. Results: A clinical success rate of 90.0% and a radiographic success rate of 77.3% were obtained. Enamel defects were found in 6.8% of permanent successors and in patients who were significantly younger at the time of root canal therapy treatment (p = .001). Treated molars exfoliated on average 5.8 months sooner than contralateral teeth (p<0.001). Conclusions: Formocresol and ZOE RCT is a viable treatment for necrotic primary molars and yielded very high clinical success rates with moderate radiographic success rates.

<p>Optoelectronic properties of the II-VI semiconductor zinc oxide (ZnO) have been studied scientifically for almost 60 years; however, many fundamental questions remain unanswered about its two primary emission bands--the exciton-related luminescence in the ultraviolet and the defect-related emission band centered in the green portion of the visible spectrum. The work in this dissertation was motivated by the surprising optical properties of a ZnO nanowire sample grown by the group of Prof. Jie Liu, Department of Chemistry, Duke University. We found that this nanowire sample exhibited defect-related green/white emission of unprecedented intensity relative to near-band-edge luminescence. The experimental work comprising this dissertation was designed to explain the optical properties of this ZnO nanowire sample. Understanding the physics underlying such exceptional intensity of green emission addresses many of the open questions of ZnO research and assesses the possibility of using ZnO nanostructures as an ultraviolet-excited, broadband visible phosphor.</p><p>The goal of this dissertation is to provide insight into what factors influence the radiative and nonradiative recombination efficiencies of ZnO by characterizing simultaneously the optical properties of the near-band-edge ultraviolet and the defect-related green emission bands. Specifically, we seek to understand the mechanisms of ultraviolet and green emission, the mechanism of energy transfer between them, and the evolution of their emission efficiencies with parameters such as excitation density and sample temperature. These fundamental but unanswered questions of ZnO emission are addressed here by using a novel combination of ultrafast spectroscopic techniques in conjunction with a systematic set of ZnO samples. Through this systematic investigation, ZnO may be realistically assessed as a potential green/white light phosphor.</p><p>Photoluminescence techniques are used to characterize the thermal quenching behavior of both emission bands in micrometer-scale ZnO powders. Green luminescence quenching is described by activation energies associated with bound excitons. We find that green luminescence efficiency is maximized when excitons are localized in the vicinity of green-emitting defects. Subsequent photoluminescence excitation measurements performed at multiple temperatures independently verified that green band photoluminescence intensity directly correlates with the photogenerated exciton population.</p><p>The spatial distributions of green-emitting defects and nonradiative traps are elucidated by an innovative combination of quantum efficiency and time-integrated/resolved photoluminescence measurements. By combining these techniques for the first time, we take advantage of the drastically different absorption coefficients for one- and two-photon excitations to provide details about the types and concentrations of surface and bulk defects and to demonstrate the non-negligible effects of reabsorption. A comparison of results for unannealed and annealed ZnO powders indicates that the annealing process creates a high density of green-emitting defects near the surface of the sample while simultaneously reducing the density of bulk nonradiative traps. These experimental results are discussed in the context of a simple rate equation model that accounts for the quantum efficiencies of both emission bands.</p><p>For both femtosecond pulsed and continuous-wave excitations, the green band efficiency is found to decrease with increasing excitation density--from 35% to 5% for pulsed excitation spanning 1-1000 uJ/cm<super>2</super>, and from 60% to 5% for continuous excitation in the range 0.01-10 W/cm<super>2</super>. On the other hand, near-band-edge emission efficiency increases from 0.4% to 25% for increasing pulsed excitation density and from 0.1% to 0.6% for continuous excitation. It is shown experimentally that these changes in efficiency correspond to a reduction in exciton formation efficiency. The differences in efficiencies for pulsed versus continuous-wave excitation are described by changes in the relative rates of exciton luminescence and exciton capture at green defects based on an extended rate equation model that accounts for the excitation density dependence of both luminescence bands.</p><p>In using a systematic set of ZnO samples and a novel combination of optical techniques to characterize them, this body of work presents a comprehensive and detailed physical picture of recombination mechanisms in ZnO. The insight provided by these results has immediate implications for material growth/processing techniques and should help material growers control the relative efficiencies of ultraviolet, green/visible, and nonradiative recombination channels in ZnO.</p> / Dissertation

This thesis reports on the use of sputter-deposited zinc-oxide as a transduction mechanism to actuate and sense single crystal silicon (SCS) microelectromechanical (MEMS) resonators. Low frequency prototypes of piezo-on-silicon resonators with operating frequencies in the range of hundreds of kHz were implemented using micromechanical single crystal silicon clamped-clamped beam resonators. The resonators reported here extend the frequency of this technology into very high frequency (VHF range) by using in-plane length extensional bulk resonant modes. This thesis outlines the design, implementation and characterization of high-frequency single crystal silicon (SCS) block resonators with piezoelectric electromechanical transducers. The resonators are fabricated on 4m thick SOI substrates and use sputtered ZnO as the piezo material. The centrally supported block resonators operate in their first and higher order length extensional bulk modes with high quality factor (Q). Measurement results are in good agreement with the developed ANSYS simulations.

In this study, we used two types of materials as working electrode of DSSC, commercial TiO2 (P25) nanoparticle and ZnO nanotip. First part, we sintered TiO2 electrode in nitrogen and treat TiO2 electrode by UV light irradiation, in order to increase dye adsorption onto TiO2. Second part, we used three different buffer layers to grow ASD-ZnO nanotip as working electrode, sputtered-ZnO, sputtered-AZO and spin-coating TiO2. The hetrojuction is formed at the interface of ZnO nanotip/TiO2 buffer layers due to the different materials between ZnO and TiO2, which is beneficial for electron-hole separation. The morphology was measured by field emission scanning electron microscope (FE-SEM, Philip XL-40FEG). The sheet resistivity was measured by four-point probe. The crystallinity was examined by X-Ray diffraction (XRD, Simens D5000). Structural and spectral properties are characterized by ultraviolet-visible spectroscopy (UV-Vis) spectroscopy. The fourier transform infrared spectroscopy (FT-IR spectroscopy, BRUKER 66v/s) deals with the infrared region of absorption spectroscopy. And the Angilent B1500A is used for current-voltage (I-V) characterization of solar cells. In our results, we enhance the performance of TiO2 electrode DSSC, the open circuit voltage can reach to 0.56 V, the short circuit current density can reach to 16.65 mA/cm2, the conversion efficiency can reach to 4.6 % and the fill factor can reach to 49.2 %. On ZnO electrode, the open circuit voltage can reach to 0.57 V, the short circuit current density can reach to 4.43 mA/cm2, the conversion efficiency can reach to 1.21 % and the fill factor can reach to 47.9 %.

The most widely used transparent conducting thin films, Indium-Tin-Oxide (ITO), will surly encounter difficulties for Indium is naturally limited and its price rising fast very year. Searching for Indium free transparent conducting oxides (TCO) becomes one of the important issues in this field. Among of which, ZnO:Al (AZO) is the most import candidate and is used, now, in photovoltaic industry. In the future, flexible substrates are necessary, therefore, to preventing degrading of TCO crystal by repeatedly bending, TCO should be produced in amorphous or nano-crystal types. By properly doping of Ti in ZnO lattice, a certain form of amorphous-nanocrystal mixture films can be obtained at room temperature. Unfortunately, amorphous or nano-crystal with poor crystal structure suppress the electric conduction. Growth films at few hundred degrees may enhance the crystallization, however, the flexible substrate, such as PET, can only sustained temperature lower than 150oC. In this project, an UV assisted film growth technique is used to study the effect of the UV assistant growth on films properties. The aim of this study is wish to grow films with better crystallization at lower growth temperature. Physical properties of films are investigated by the transmittance spectroscopy (N&K analyzer), X-ray dffractometer (XRD) and atomic force microscopy (AFM). It is found that the optical band gap increases and shows an obvious blue shifting due to the short range order in the present films. All films exhibits high level of transparency in the visible range. The grazing angle incident X-ray diffraction (GID XRD) indicates that high ratio of amorphous phase for films grown at high working gas pressure and low RF power. For certain growth conditions, pure amorphous films can be obtained. Oppositely, films grown at low working gas pressure and high RF power manifest crystal growth along all directions resulting shifting and broadening in XRD peaks. Higher the Ti doping levels higher the amorphous ratio. By gown films at higher temperatures, (002) peak dominates the GID XRD measurements. It is found that the 266nm UV assisted growth enhances crystallization and roughness of films at relatively low temperature, lower than the highest sustainable temperature of PET.

Nanotechnology comprises of the understanding and control of materials and processes at the nanoscale. Among various nanostructured materials, semiconducting nanowires attract much interest for their novel physical properties and potential device applications. The unique properties of these nanowires are based on their high surface to volume ratio and quantum confinement effect. Zinc oxide, having a direct, wide bandgap and large exciton binding energy, is highly appealing for optoelectronic devices. Due to excellent optical and electrical properties, zinc oxide nanowires have been utilized to fabricate various devices such as solar cells, light emitting diodes, transistors and photodetectors. Furthermore, zinc oxide, in its natural state exhibits n-type conductivity. Addition of impurities often leads to remarkable changes in their electrical and optical properties, which open up new application areas. Among the many synthesis methods for zinc oxide nanowires, hydrothermal method is an attractive one due to its easy procedure, simple equipment and low temperature requirements. In this thesis, zinc oxide nanowires were grown and doped by hydrothermal method. Different metal dopants such as copper, silver and aluminum were used for this purpose. These metals were selected as dopants due to their effect on magnetic properties, p-type conduction and electrical conductivity of ZnO nanowires, respectively. Doped nanowires were fully characterized and the changes in their physical properties were investigated. In addition, hydrothermally synthesized pure and aluminum doped zinc oxide nanowires were used as the electrically active components in ultraviolet photodetectors. Silver nanowires were utilized as transparent electrodes. Optoelectronic properties of the detectors were examined. Effect of in-situ annealing and nanowire length was investigated. Short recovery time, around 4 seconds, with a decent on/off ratio of 2600 was obtained. This design provides a simple and cost effective approach for the fabrication of high performance ultraviolet photodetectors.