No description available.

No description available.

by Hui Koon-chung = 由電子束照射引起氧化金屬膜覆蓋的氧化鋅之光學特性 / 許冠中. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2004. / Includes bibliographical references (leaves 87-89). / Text in English; abstracts in English and Chinese. / by Hui Koon-chung = You dian zi shu zhao she yin qi yang hua jin shu mo fu gai de yang hua xin zhi guang xue te xing / Xu Guanzhong. / ABSTRACT --- p.i / ACKNOWLEDGMENTS --- p.iii / TABLE OF CONTENTS --- p.iv / LIST OF FIGURES --- p.vi / LIST OF TABLES --- p.x / Chapter 1. --- Introduction --- p.1 / Chapter 1.1 --- Motivation --- p.1 / Chapter 1.2 --- Overview of ZnO / Chapter 1.3 --- Overview of the Thesis / Chapter 2. --- Experimental conditions and procedures --- p.11 / Chapter 2.1 --- Samples preparation / Chapter 2.2 --- Optical and electrical Characterizations of ZnO / Chapter 2.2.1 --- Setup of cathodoluminescence (CL) spectroscopy / Chapter 2.2.2 --- Setup of photoluminescence (PL) spectroscopy / Chapter 2.2.3 --- Setup of photoconductivity measurement / Chapter 2.2.4 --- Setup of atomic force microscopy AFM / Chapter 2.2.5 --- X-ray photoelectron spectroscopy (XPS) / Chapter 3. --- Experimental results and data analysis --- p.21 / Chapter 3.1 --- The luminescence of ZnO --- p.21 / Chapter 3.2 --- Effects of metal capped layer in luminescence --- p.24 / Chapter 3.3 --- Optical memory effect of A1 capped ZnO --- p.28 / Chapter 3.4 --- The XPS study ofAl capped ZnO --- p.33 / Chapter 3.5 --- Optical properties and photoconductivity studies of AlOx-capped ZnO --- p.35 / Chapter 3.6 --- Time- and Electron-dose dependent CL of AlOx capped ZnO --- p.41 / Chapter 3.7 --- Dependence of band-edge enhancement on Deep Level to band-edge emission ratio --- p.53 / Chapter 3.8 --- Temperature-dependent CL of AlOx capped ZnO --- p.56 / Chapter 3.9 --- Electrical measurement of luminescence enhanced ZnO --- p.64 / Chapter 4. --- Discussion --- p.69 / Chapter 4.1 --- General discussion --- p.69 / Chapter 4.2 --- The effect of AlOx capping on the optical properties of ZnO --- p.70 / Chapter 4.3 --- The action of e-beam irradiation on the enhancement of band-edge emission --- p.73 / Chapter 4.4 --- The function of AlOx layer when under electron irradiation --- p.83 / Chapter 5. --- Conclusions --- p.85 / Reference --- p.87

Yin, Weixin = 非晶液態鈀-鎳-磷合金相位分離的證據 / 殷瑋欣. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2011. / Includes bibliographical references. / Abstracts in English and Chinese. / Yin, Weixin = Fei jing ye tai ba-nie-lin he jin xiang wei fen li de zheng ju / Yin Weixin. / Acknowledgement --- p.i / Abstract --- p.ii / Contents --- p.iv / Chapter Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- A Brief Introduction to Metallic Glass --- p.1 / Chapter 1.2 --- Homogeneous Nucleation Frequency --- p.3 / Chapter 1.3 --- Heterogeneous Nucleation Frequency --- p.4 / Chapter 1.4 --- Spinodal Decomposition --- p.5 / Chapter 1.5 --- Conditions for Metallic Glasses Formation --- p.8 / Chapter 1.6 --- How to Get Large Undercooling --- p.9 / Chapter 1.7 --- Liquid Phase Separation --- p.10 / References --- p.12 / Figures --- p.13 / Chapter Chapter 2 --- Experimental Procedures and Techniques of Transmission Electron Microscopy --- p.18 / Chapter 2.1 --- Sample preparation --- p.18 / Chapter 2.1.1 --- Ni2P Preparation --- p.18 / Chapter 2.1.2 --- Alloying --- p.18 / Chapter 2.1.3 --- Fluxing --- p.18 / Chapter 2.2 --- Introduction to TEM Specimen Preparation --- p.19 / Chapter 2.2.1 --- "Grinding, Polishing and Punching" --- p.19 / Chapter 2.2.2 --- Final Thinning by Ion Miller --- p.20 / Chapter 2.2.3 --- Final Thinning by Twin Jet --- p.20 / Chapter 2.3 --- Introduction to Transmission Electron Microscopy Techniques --- p.21 / Chapter 2.3.1 --- Basic Instrumentations of TEM --- p.21 / Chapter 2.3.2 --- Elastic Scattering and Inelastic Scattering --- p.21 / Chapter 2.3.3 --- Image Contrast --- p.22 / Chapter 2.3.4 --- Dark Field Image and Bright Field Image --- p.24 / Chapter 2.3.5 --- EDX Mapping --- p.24 / Chapter 2.3.6 --- High Resolution Images --- p.25 / References --- p.26 / Figures --- p.27 / Chapter Chapter 3 --- Evidence of amorphous/liquid phase separation in Pd41.25Ni41.25P17.5 alloy --- p.32 / Chapter 3.1 --- Introduction --- p.32 / Chapter 3.2 --- Experimental --- p.34 / Chapter 3.3 --- Discussions --- p.42 / References --- p.44 / Figures --- p.45 / Chapter Chapter 4 --- Conclusions --- p.68

過去幾十年當中，金屬玻璃（包括塊狀金屬玻璃）中非晶相分離的發生已經成為了一個具有爭議性的課題。一些報告報導在具有負混合熱的Pd-Ni-P合金體系中發生了非晶相分離。然而，有一些報告聲稱相分離不能在Pd-Ni-P非晶合金中被觀察到。文獻分析表明，困難在於缺乏直接的實驗證據。 / 為了解決這個難題，示差掃描量熱儀、高分辨電子顯微鏡、掃描透射模式下的高角環射暗場相、以及能量色散X射線光譜儀等檢測儀器在我們實驗當中被使用。同時為了清楚展示非晶相分離反應，在過冷Pd₄₁.₂₅Ni₄₁.₂₅P₁₇.₅熔體被冷卻為固態非晶樣品之前引入了中間熱退火處理。 / 實驗研究了三種經由不同路徑製備的A、B、C型號樣品。結果表明在非晶/液態Pd₄₁.₂₅Ni₄₁.₂₅P₁₇.₅合金中可能存在獨特的短程有序結構，它會導致相分離的發生。同时研究發現，在大約625 K，調幅分解的持續時間的下限大概是200 s。調幅分解的時間常數R在大約625 K 下為0.002 s⁻¹。三种类型样品在不同的溫度下被退火從而獲得部分的結晶。A型號和B型號具有相似的行為。在低溫下，圓形的核心首先形成，接著發生共晶反應。在高溫下，出現了一種形狀為立方體的析出相。在C型號的樣品當中，核心和立方的析出物同時被發現。但是核心的成分分佈與A和B型號中出現的不同。同時，隨著退火時間的加長形核的數量也具有獨特的行為表現。作為對比，Pd₄₀Ni₄₀P₂₀塊狀金屬玻璃的結晶行為也被展開了研究。同樣的，以形成核心開始，但是它的成分分佈異於A和B型號的樣品。 / Amorphous phase separation in metallic glass (including bulk metallic glass) has been a controversial issue in the past several decades. There are reports saying that amorphous phase separation occurs in Pd-Ni-P, which has a negative heat of mixing among its constituent elements. However, there are also as many reports claiming that phase separation is absent in amorphous Pd-Ni-P alloys. The lack of direct experimental evidence makes the issue to be difficult to be resolved. / To solve this problem, differential scanning calorimetry (DSC), high resolution transmission electron microscopy (HRTEM), high angle annular dark field (HAADF) in scanning transmission electron microscopy, and energy dispersive X-ray spectroscopy (EDX) have been employed. Intermediate thermal annealing is introduced before an undercooled Pd₄₁.₂₅Ni₄₁.₂₅P₁₇.₅ melt is cooled down to become a solid amorphous specimen. / A-type, B-type, and C-type specimens of composition, Pd₄₁.₂₅Ni₄₁.₂₅ P₁₇.₅, have been prepared via three different cooling paths. It was found that amorphous phase separation indeed occurs in C-type specimens. Results suggest that there may be unique short range orders in amorphous/liquid Pd₄₁.₂₅Ni₄₁.₂₅P₁₇.₅, which are responsible for the phase separation. Experimental arrangements were made to study the occurrence of spinodal reaction in undercooled molten Pd₄₁.₇₅Ni₄₁.₇₅P₁₇.₅ alloys as a function of time. The lower bound of the duration of the spinodal decomposition at a temperature of {U+2248}625 K is about 200 s and the time constant R of the spinodal decomposition at a temperature of {U+2248}625 K is 0.002 s⁻¹. / A-type and B-type specimens have similar crystallization behavior. At low temperature, it starts with the formation of a spherical core and then eutectic crystallization takes over. At higher temperatures, an additional phase in the shape of a cube appears. In annealed C-type specimens, cores and cubic precipitates are also found. However, the composition profile of the cores is different and the number of nucleation events versus time has peculiar characteristics. The crystallization behavior of Pd₄₀Ni₄₀P₂₀ BMG was studied for comparison. It again starts out with the formation of a core, but with a composition profile different from those of A-type and B-type specimens. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Lan, Si = 對於具有負混合熱的塊狀金屬玻璃非晶相分離的研究 / 蘭司. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2012. / Includes bibliographical references. / Abstract also in Chinese. / Lan, Si = Dui yu ju you fu hun he re de kuai zhuang jin shu bo li fei jing xiang fen li de yan jiu / Lan Si. / Abstract of thesis --- p.i / Acknowledgements --- p.v / List of Tables --- p.x / List of Figures --- p.xi / Chapter Chapter 1 --- Introduction and literature review --- p.1 / Chapter 1.1 --- Introduction to metallic glasses --- p.1 / Chapter 1.1.1 --- Background of metallic glasses --- p.1 / Chapter 1.1.2 --- Glass transition --- p.2 / Chapter 1.1.3 --- The undercooling of liquids --- p.3 / Chapter 1.1.4 --- Crystal nucleation and growth in liquids --- p.3 / Chapter 1.1.4.1 --- Crystal Nucleation in liquids --- p.3 / Chapter 1.1.4.2 --- Crystal growth in liquids --- p.5 / Chapter 1.1.4.3 --- TTT diagram --- p.6 / Chapter 1.1.4.4 --- Crystallization in metallic glasses --- p.6 / Chapter 1.1.5 --- Glass formation methods and systems --- p.6 / Chapter 1.1.6 --- Glass forming ability and criteria --- p.8 / Chapter 1.1.7 --- Properties and applications --- p.9 / Chapter 1.2 --- The basic theory of phase separation in a binary system --- p.10 / Chapter 1.2.1 --- Thermodynamic background --- p.10 / Chapter 1.2.2 --- Solid state phase separation --- p.11 / Chapter 1.2.2.1 --- A miscibility gap of binary mixture --- p.11 / Chapter 1.2.2.2 --- Nucleation and growth mechanism --- p.12 / Chapter 1.2.2.3 --- Spinodal decomposition mechanism --- p.13 / Chapter 1.2.3 --- Liquid state miscibility gap in a binary system --- p.21 / Chapter 1.3 --- Literature review for phase separation in metallic glasses --- p.23 / Chapter 1.4 --- The aim of this thesis --- p.28 / Figures --- p.30 / References --- p.39 / Chapter Chapter 2 --- Experiments and characterization --- p.44 / Chapter 2.1 --- Introduction and the outline of the experiments --- p.44 / Chapter 2.2 --- Sample preparation --- p.45 / Chapter 2.2.1 --- Bulk metallic glasses preparation --- p.45 / Chapter 2.2.1.1 --- Preparation of clean fused silica tubes --- p.45 / Chapter 2.2.1.2 --- Weighing --- p.46 / Chapter 2.2.1.3 --- Alloying --- p.46 / Chapter 2.2.1.4 --- Fluxing --- p.47 / Chapter 2.2.2 --- Thermal annealing --- p.49 / Chapter 2.2.3 --- Specimens preparation for characterization --- p.50 / Chapter 2.2.3.1 --- Cutting, molding, grinding and polishing --- p.50 / Chapter 2.2.3.2 --- Etching --- p.51 / Chapter 2.2.3.3 --- Thinning for TEM foils --- p.51 / Chapter 2.3 --- Characterization --- p.55 / Chapter 2.3.1 --- Differential scanning calorimetry (DSC) --- p.55 / Chapter 2.3.2 --- Scanning electron microscopy (SEM) --- p.55 / Chapter 2.3.3 --- Transmission electron microscopy (CTEM and HRTEM) --- p.57 / Chapter 2.3.4 --- High angle annular dark field (HAADF) in Scanning transmission electron microscopy (STEM) --- p.58 / Chapter 2.3.5 --- Energy dispersive X-ray spectroscopy (EDX) --- p.59 / Figures --- p.62 / References --- p.69 / Chapter 3 --- p.70 / Chapter 3.1 --- Introduction --- p.70 / Chapter 3.2 --- Materials and Experimental --- p.73 / Chapter 3.3 --- Results --- p.75 / Chapter 3.3.1 --- Thermal behaviors of three types of specimens --- p.75 / Chapter 3.3.2 --- Microstructures of three types of specimens --- p.75 / Chapter 3.3.2.1 --- A-type specimens --- p.75 / Chapter 3.3.2.2 --- B-type specimens --- p.76 / Chapter 3.3.2.3 --- C-type specimens --- p.76 / Chapter 3.4 --- Discussion --- p.78 / Chapter 3.5 --- Conclusions --- p.79 / Chapter 3.6 --- Afterward --- p.79 / Figures --- p.80 / References --- p.89 / Chapter Chapter 4 --- The time constant of the spinodal decomposition in Pd₄₁.₇₅Ni₄₁.₇₅P₁₇.₅ bulk metallic glasses --- p.92 / Chapter 4.1 --- Introduction --- p.92 / Chapter 4.2 --- Materials and experimental --- p.92 / Chapter 4.3 --- Results --- p.94 / Chapter 4.3.1 --- Thermal behaviors --- p.94 / Chapter 4.3.2 --- Microstructures --- p.94 / Chapter 4.4 --- Discussion --- p.96 / Chapter 4.5 --- Conclusions --- p.98 / Figures --- p.100 / References --- p.123 / Chapter Chapter 5 --- Crystallization in homogeneous and phase-separated Pd₄₁.₂₅Ni₄₁.₂₅P₁₇.₅ bulk metallic glasses --- p.125 / Chapter 5.1 --- Introduction --- p.125 / Chapter 5.2 --- Experiments --- p.126 / Chapter 5.3 --- Results --- p.128 / Chapter 5.3.1 --- Low temperature thermal annealing at 613 K with 0≤t{U+2090} ≤ 8 h --- p.128 / Chapter 5.3.1.1 --- A-type and B-type specimens --- p.128 / Chapter 5.3.1.2 --- C-type specimens --- p.130 / Chapter 5.3.1.3 --- Pd₄₀Ni₄₀P₂₀ BMG --- p.132 / Chapter 5.3.2 --- High temperature thermal annealing --- p.133 / Chapter 5.3.2.1 --- A-type and B-type specimens --- p.133 / Chapter 5.3.2.2 --- C-type specimens --- p.135 / Chapter 5.3.2.3 --- Pd₄₀Ni₄₀P₂₀ BMG --- p.137 / Chapter 5.4 --- Discussion --- p.137 / Chapter 5.4.1 --- Formation of spherical cores --- p.138 / Chapter 5.4.1.1 --- A-type and B-type Pd₄₁.₇₅Ni₄₁.₇₅P₁₇.₅ specimens --- p.138 / Chapter 5.4.1.2 --- C-type Pd₄₁.₇₅Ni₄₁.₇₅P₁₇.₅ specimens --- p.139 / Chapter 5.4.1.3 --- Pd₄₀Ni₄₀P₂₀ BMG --- p.140 / Chapter 5.4.2 --- Formation of cubic precipitates --- p.141 / Tables --- p.142 / Figures --- p.144 / References --- p.188 / Chapter Chapter 6 --- Conclusions --- p.190 / Bibliography --- p.192

by Yuen Cheong Wing. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1996. / Includes bibliographical references (leaves [138]-[142]). / by Yuen Cheong Wing. / Acknowledgments --- p.ii / Abstract --- p.iii / Table of Contents --- p.v / Chapter Chapter 1: --- Introduction --- p.1-1 / Chapter 1.1 --- What is Metallic Glass? --- p.1-1 / Chapter 1.2 --- Use of Metallic Glass --- p.1-3 / Chapter 1.3 --- A Dilemma --- p.1-4 / Chapter 1.4 --- Glass Forming Ability --- p.1-5 / Chapter 1.5 --- Role of Liquid State Phase Separation in GFA --- p.1-6 / References --- p.1-9 / Figure --- p.1-10 / Chapter Chapter 2: --- Phase Separation Theory --- p.2-1 / Chapter 2.1 --- Free Energy Curve --- p.2-1 / Chapter 2.2 --- Nucleation and Growth --- p.2-2 / Chapter 2.2.1 --- Liquid state nucleation and growth --- p.2-2 / Chapter 2.2.2 --- Nucleation and growth during solidification --- p.2-4 / Chapter 2.3 --- Spinodal Decomposition --- p.2-5 / Chapter 2.3.1 --- Cahn-Hilliard linearized equation --- p.2-6 / Chapter 2.3.2 --- Temporal evolution --- p.2-9 / References --- p.2-12 / Figures --- p.2-15 / Chapter Chapter 3 ： --- Experimental Setup and Techniques --- p.3-1 / Chapter 3.1 --- Technique in Achieving High Undercooling --- p.3 -1 / Chapter 3.1.1 --- Effects and limitation of B203 --- p.3-1 / Chapter 3.1.2 --- Preparation of B203 --- p.3-3 / Chapter 3.1.3 --- Cleansing of apparatus --- p.3-4 / Chapter 3.2 --- Experimental --- p.3-5 / Chapter 3.2.1 --- Sample preparation --- p.3-6 / Chapter 3.2.2 --- Experimental setup --- p.3-7 / Chapter 3.2.3 --- Procedures --- p.3-8 / Chapter 3.3 --- Observing the Microstructure --- p.3-9 / Chapter 3.3.1 --- Cutting --- p.3-10 / Chapter 3.3.2 --- Molding --- p.3-10 / Chapter 3.3.3 --- Polishing --- p.3-11 / Chapter 3.3.4 --- Etching --- p.3-12 / Chapter 3.3.5 --- Observation --- p.3-12 / References --- p.3-14 / Table --- p.3-15 / Figures --- p.3-16 / Chapter Chapter 4: --- Metastable liquid phase separationin undercooled molten PD40. 5]\l40.5P19 --- p.4-1 / Abstract --- p.4-1 / References --- p.4-9 / Figures --- p.4-10 / Chapter Chapter 5 ： --- Transformation in undercooled molten PD40.5NI40.5P19 --- p.5-1 / Chapter 5.1 --- Abstract --- p.5-1 / Chapter 5.1 --- Introduction --- p.5-2 / Chapter 5.3 --- Experimental --- p.5-4 / Chapter 5.4 --- Results --- p.5-6 / Chapter 5.5 --- Discussions --- p.5-13 / References --- p.5-20 / Figures --- p.5-22 / Chapter Chapter 6 ： --- Solidification of liquid spinodal in undercooled PD40.5NI40.5P19 --- p.6-1 / Chapter 6.1 --- Abstract --- p.6-1 / Chapter 6.2 --- Introduction --- p.6-2 / Chapter 6.3 --- Experimental --- p.6-3 / Chapter 6.4 --- Results --- p.6-5 / Chapter 6.5 --- Discussions --- p.6-10 / References --- p.6-17 / Figures --- p.6-18 / Chapter Chapter 7: --- Conclusion --- p.7-1 / References --- p.7-4 / Bibliography --- p.B-1

Metais são bastante usados como materiais implantáveis, principalmente para dispositivos feitos na área de ortopedia. Há uma constante relação dos processos de corrosão nesse biomateriais com a agressividade do meio fisiológico. Usando quatro tipo de metais e ligas metálicas – titânio puro, liga de titânio, aço inoxidável de baixo carbono e liga de cobalto – o processo de corrosão foi estudado. Além disso, o desempenho desses materiais revestidos com nitreto de titânio foi avaliado. Dois processos de revestimento por PVD – evaporação e magnetron sputtering – foram executados, verificando a eficiência desses materiais em meio fisiológico - O melhor comportamento se deu para o revestimento obtido por evaporação. O mecanismo de corrosão predominante para as amostras foi indicado. / Metals are very much used as implantable materials mainly for the construction of devices orthopaedic area. There is a constant concern about the corrosion process in those metallic biomaterials due to the aggressiveness of the physiological environment. By using four types of metals and metallic alloys – pure titanium, titanium alloy, low carbon stainless steel and cobalt-chromium alloy – the corrosion process in physiologic environment has been studied. Also, the performance of such materials coated with titanium nitrate was evaluated. Two PVD coating methods – evaporation and magnetron sputtering – were performed, and the efficiency of those materials in physiologic medium was verified. The best behaviour was found by the evaporation coating method. The predominant corrosion mechanism for coated samples was suggested.

Orientador: Marian Rosaly Davolos / Coorientador: Marco Aurélio Cebim / Banca: Iguatemy Lourenço Brunetti / Banca: Vera Regina Leopoldo Constantino / Resumo: O uso de protetores solares para a proteção da pele contra os raios UV emitidos pelo sol está se tornando imprescindível e o estudo tanto de filtros inorgânicos, orgânicos como das suspensões estáveis que constituem os protetores requerem pesquisa acadêmica. Este trabalho tem por objetivo o desenvolvimento de novos tipos de filtros solares através da obtenção de complexos metálicos de Zn2+, de Ce3+ e heterobimetálicos de Zn2+ e Ce3+ a fim de utilizá-los na formulação de protetores solares com melhor desempenho no fator de proteção solar (FPS) e com menor irritabilidade. Dentre os diversos filtros orgânicos existentes foi escolhido como ligante o flavonoide quercetina (3,3',4',5,7 pentahidroxiflavona), um composto natural que apresenta propriedades bactericidas, antiinflamatórias e antioxidantes, além de absorção intensa na região UVA e UVB do espectro eletromagnético. Os complexos obtidos foram caracterizados por difração de raios X, análises térmica e elementar, espectroscopia vibracional de absorção na região do infravermelho, espectroscopia eletrônica de absorção na região do UV-VIS, espectroscopia de fotoluminescência. Os complexos de Zn2+ com quercetina, denominados de complexo 1 e complexo 2, apresentam interação metal-ligante pelos grupos 4-oxo e 3-OH, e fórmulas mínimas [Zn(Q)(H2O)2] e [Zn(Q)2(H2O)2] respectivamente. O complexo de Ce3+ com quercetina, denominado de complexo 4, apresenta a interação metal-ligante ocorrendo pelos grupos 4-oxo e 5-OH da quercetina e a fórmula mínima [Ce(Q)3(H2O)2]. O complexo heterobimetálico de Zn2+ e Ce3+, complexo H, apresenta fórmula mínima [CeZn(Q)2(H2O)4]Cl com seu espectro UV-VIS sugerindo interação dos centros metálicos com dois grupos principais da molécula de quercetina. A atividade antioxidante desses complexos frente... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The use of sunscreens to protect the skin against UV rays emitted by the sun is becoming crucial and the study of both inorganic and organic filters, as well as stable suspensions which are the sunscreens require academic research. This work aims the development of new types of sunscreens by obtaining metal complexes of Zn2+, Ce3+ and hetero bimetallic complexes of Zn2+ and Ce3+ in order to use them in the sunscreen formulations to provide better performance in sun protection factor (FPS) and less irritability. Among the many existing organic filters it was chosen as ligand the flavonoid quercetin (3, 3', 4', 5,7 pentahidroxiflavone), a natural compound that has antibacterial, anti-inflammatory and antioxidants, besides intense absorption in the UVA and UVB region of electromagnetic spectrum. The complexes obtained in powder form were characterized by X-ray diffraction, elemental and thermal analyzes, infrared vibrational spectroscopy, electronic absorption in the UV-VIS and photoluminescence spectroscopies. Complexes of Zn2+ with quercetin, designated complex 1 and complex 2 show metal-ligand interaction by the 4-oxo and 3-OH groups, and formulas [Zn(Q)(H2O)2] and [Zn(Q)2(H2O)2] respectively. The complex of Ce3+ with quercetin, called complex 4 shows the metal-ligand interaction by the 4-oxo and 5-OH groups and formula [Ce(Q)3(H2O)2]. The hetero bimetallic complex of Zn2+ and Ce3+ with quercetin, called complex H, presents formula [CeZn(Q)2(H2O)4]Cl and its UV-VIS spectrum suggests interaction of the metal centers with two main groups of quercetin. The antioxidant activity of these complexes against the reactive species and / or free radical ABTS•+, DPPH• , O2• -, HOCl / OCl- and H2O2 is generally superior to the ligand indicating that complexation of quercetin with metals enhances its antioxidant activity. The sunscreen formulation... (Complete abstract click electronic access below) / Mestre

Due to the trend of increasing environmental demands put on civil aviation, manufacturersof commercial aircraft engines meet increased pressure to reduce weight. Modernturbofan engines represent up to almost one tenth of an aircraft's total weight, meaning areduction of engine component weight of just 30 kg is estimated to reduce CO2 emissionsby 400 tonnes over the lifetime of a medium sized commercial aircraft. At the sametime turbine casings are required to fully prevent debris to escape in the event of bladefailure, to prevent further damage to critical systems. For new designs to be approvedthe Federal Aviation Regulations (FAR) states that the containment capability of a suggesteddesign solution must be experimentally established, a process associated with highcosts and long lead times. The industry therefore more frequently relies on numericalsimulations as part of all stages in the design process. For simulations to replace theexpensive experiments in nding the nal optimum design regarding weight and safety,the accuracy of the used models have to be improved.This thesis aims to provide increased accuracy in the numerical predictions by developingexperimental procedures to test material close to the operational conditions of thecontainment structure. This is realised by performing experiments at high-strain ratesand elevated temperatures in a high-velocity tensile testing machine combined with aninduction heater. Sheet specimens of varying geometries are loaded in tension to achievedierent stress states for covering dierent failure modes. Furthermore, high-speed photographyand Digital Image Correlation are utilised to track in-plane deformations. Theresulting local deformations are then used to derive the stress-strain hardening relationand the evolution of the stress state from initial loading up to fracture. The obtaineddata are nally used to calibrate strain rate and thermal dependent plasticity and fracturemodels. To validate the calibrated models so-called reverse impact testing was used,where the resulting force of a material sample impacting an instrumented target wasquantied. The experiment was straightforward to model numerically since the specimenies freely without constraints, thereby avoiding complex boundary conditions.The characterisation method was developed and performed on nickel based Alloy 718.This material is known for its high strength and good corrosion resistance at high temperaturesand is therefore commonly used in hot parts of aircraft engines, such as thecontainment structures of the low-pressure part of the engine turbine. All material fortesting and validation was supplied from one single heat and batch, aged using the sameheat treatment conditions, to ensure consistent mechanical properties. The results fromthe characterisation procedure showed that the plastic ow of Alloy 718 is moderatelystrain rate and temperature dependent while the fracture is clearly stress state dependent.

Neste trabalho desenvolveu-se um sensor eletroquímico a partir da modificação de superfície de um eletrodo de carbono vítreo com nanopartículas metálicas de Pt e intermetálicas de NiSb suportadas em carbono Vulcan® XC72. Tal modificação visou à obtenção de um sensor de baixo custo, simples e rápido para determinação do cloridrato de tetraciclina (TTC). A tetraciclina é um fármaco com propriedades antibióticas amplamente utilizado na saúde humana e animal devido sua baixa toxicidade e fácil obtenção. A modificação de superfície do eletrodo de trabalho foi realizada a partir da adição de uma suspensão das nanopartículas em dimetilformamida (DMF) (1 mg/1 mL) sobre a superfície do eletrodo previamente limpo e os estudos voltamétricos conduzidos utilizando as técnicas de voltametria cíclica, voltametria de pulso diferencial e cronoamperometria. Como consequência dos resultados obtidos, prosseguiu-se apenas com os estudos da nanopartícula de Pt na construção de um sensor para determinação da TTC. As nanopartículas apresentam propriedades diferentes daquelas exibidas pelo mesmo material quando estes se encontram em partículas de maior tamanho como bulks, e dentre suas principais características, o aumento da área superficial provocado pela modificação do eletrodo mostrou resultados promissores na detecção e quantificação do analito. Após diversos estudos sobre o eletrólito de suporte e o pH, obteve-se a melhor resposta voltamétrica em solução de tampão fosfato 0,10 mol L-1 pH 3,0 através da voltametria cíclica tanto na determinação do analito em água purificada quanto na determinação em urina sintética. O eletrodo modificado com nanopartículas de Pt apresentou resposta linear na faixa de 9,99 e 44,01 µmol L-1, limite de detecção 4,28 µmol L-1 e limite de quantificação 14,26 µmol L-1. A aplicação do eletrodo em uma amostra de urina sintética ocorreu com sucesso, alcançando um valor de concentração com diferença de 3% para o valor real. / In this work it was developed an electrochemical sensor by the surface modification of a glassy carbon electrode with metallic Pt nanoparticles and intermetallic NiSb nanoparticles in Vulcan® XC72 carbon as the support. Such surface modification sought to obtain a low cost sensor, easy to work and quick working to determine tetracycline hydrochloride. The tetracycline is a drug with antibiotics properties widely used in human and animal treatment due to its low toxicity and easy obtainability. The surface modification of the work electrode was accomplished through the addition of a suspension of the nanoparticles in dimethylformamide (1 mg/1 mL) in the electrode surface previously cleaned and the voltammetric studies conducted with the use of techniques such as cyclic voltammetry, differential pulse voltammetry and chronoamperometry. As a consequence of the obtained results, only the studies with the sensor developed with Pt nanoparticles were continued for the tetracycline determination. The nanoparticles presents different properties of those shown by the same material when these are in bigger forms, such as bulks and among the main characteristic, the superficial area increase caused by the electrode modification shown promising results for the detection and quantification of the analyte. After several studies about the supporting electrolyte and the pH, it was obtained a better voltammetric response in phosphate buffer solution 0.1 mol L-1 and pH 3.0 for the determination of the analyte in purified water and synthetic urine. The modified electrode with metallic Pt nanoparticles had a linear response in the range 9.99 to 44.01 µmol L-1 with a detection limit of 4.28 µmol L-1 and quantification limit of 14.26 µmol L-1. The electrode application in a synthetic urine sample was a success, reaching concentration values with a difference within 3% of the real value.