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1
Galazzi, Rodrigo Moretto 1988. "Emprego da técnica MF-HG-AAS na determinação de estanho : análise de parâmetros analíticos e morfológicos do atomizador metálico." [s.n.], 2013. http://repositorio.unicamp.br/jspui/handle/REPOSIP/248591.
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Orientador: Marco Aurélio Zezzi ArrudaDissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Química
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Resumo: Nessa dissertação, otimizou-se um método para a determinação de estanho (Sn) em amostras biológicas empregando a técnica de Espectrometria de Absorção Atômica por Geração de Hidretos e Forno Metálico (MF-HG-AAS, do inglês Metallic Furnace Hydride Generation Atomic Absorption Spectrometry). Foram avaliadas algumas variáveis químicas como o tipo e concentração do carregador/diluente da solução padrão, concentração do redutor tetraidridoborato (-1) de sódio (THB) e concentração de hidróxido de sódio, bem como variáveis físicas do sistema dentre elas a vazão de carregador, proporção de acetileno:ar na chama, volume de solução injetado, vazão de argônio como gás de arraste, vazão de água no nebulizador e área total de furos no tubo metalico Inconel600®. Foi realizado um estudo do efeito de memória observado em condições de chama oxidante nas vazões de 1,5:9; 1,4:9; 1,3:9; 1,4:10; 1,4:8 e 1,5:11 L min de acetileno:ar, respectivamente. Em todas essas proporções de chama diferentes da otimizada (1,5:10 L min acetileno:ar) há efeito de memória, o que é extremamente indesejável. Após a otimização do sistema, foram realizados testes de exatidão e precisão do mesmo com os materiais PACS-2 (sedimento) e SRM 1643e (amostra de água) em que, em ambos, foi possível recuperar o Sn adicionado obtendo limites de detecção (LD) de 7,1 mg kg e 7,6 mg L, respectivamente. Um estudo com concomitantes foi realizado para avaliar se algum dos elementos em questão poderia interferir na determinação do Sn. Foram estudados como possíveis concomitantes o cobre, chumbo e zinco em três níveis diferentes. Somente o cobre, nas razões de 1:10 e 1:20 (Sn:concomitante), interferiu na detecção de Sn. Por fim, a morfologia do atomizador foi avaliada por meio da técnica de Microscopia Eletrônica de Varredura (SEM, do inglês Scanning Electron Microscopy). Mesmo após a realização de todos os experimentos envolvendo a otimização do sistema e análise das amostras, os principais constituintes do tubo metálico Inconel600® (ferro, níquel e cromo) permaneceram homogeneamente distribuídos, indicando que esses metais podem não participar da rota de atomização do Sn. Além disso, houve formação de óxidos no atomizador que, juntamente com o uso de uma chama oxidante, sugerem uma rota de atomização do Sn via formação de óxidos. Considerando os LD, bem como a exatidão e precisão por meio da recuperação de Sn obtida nas amostras, constata-se a potencialidade da MF-HG-AAS frente a outras técnicas empregadas na determinação de Sn
Abstract: In this work, a Metallic Furnace Hydride Generation Atomic Absorption Spectrometry (MF-HG-AAS) was optimized for tin (Sn) determination in biological samples. Chemical variables, such as the type and carrier concentration, the sodium tetrahydrideborate (-1) (THB), and the sodium hydroxide concentration, as well as physical variables, such as carrier flow-rate, ratio of acetylene and air in the flame, injection volume, argon flow-rate as carrier of stannane, water flow-rate in nebulizer and total hole area of a Inconel600® metallic furnace were evaluated. A study of a memory effect observed in oxidant flame conditions such as 1.5:9; 1.4:9; 1.3:9; 1.4:10; 1.4:8 e 1.5:11 L minof acetylene:air, respectively, was realized. In any other flame flow-rate, which the optimized flame ratio (1.5:10 L min acetylene:air) was observed a memory effect, which is very undesirable. After optimizing of the system, test of accuracy and precision were realized with the PACS-2 (sediment) and SRM 1643e (water sample) materials wherein, in both, a recovery of the Sn added to the samples was possible with limits of detection (LOD) as 7,1 mg kg and 7,6 mg L, respectively. A concomitant study was carried out for checking the interferences in the Sn determination. Copper, lead and zinc at three different levels were studied as possible concomitants. Only copper, at 1:10 and 1:20 (Sn:concomitant) ratios interfered in the determination of Sn. Finally, the morphology of the atomizer employed was evaluated through Scanning Electron Microscopy (SEM) technique. Even after carrying out all experiments involved in the optimization of the system and in the sample analysis, the main constituents of Inconel600® metallic furnace (iron, nickel and chromium) remained homogeneously distributed, indicating which these elements may not participate of the Sn atomization route. Moreover, the oxide formation in the atomizer was detected, which, together with an oxidant flame used, suggests the Sn atomization route via oxides formation. Considering the LOD, as well the accuracy and precision through the Sn recovery in the samples, the MF-HG-AAS potentially is well pointed out when it is compared to other techniques employed for Sn determination
Mestrado
Quimica Analitica
Mestre em Química
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Kunati, Sandeep Reddy. "Trace Measurements of Tellurium, Tin and Other Metals by Atomic and Laser Spectroscopy Techniques." Connect to resource online, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=ysu1219695278.
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Harman, David Grant, and harmandg@hotmail com. "Mechanisms of the Intriguing Rearrangements of Activated Organic Species." The Australian National University. Faculty of Science, 2003. http://thesis.anu.edu.au./public/adt-ANU20031210.143110.
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The β-acyloxyalkyl radical rearrangement has been known since 1967 but its
mechanism is still not fully understood, despite considerable investigation. Since the
migration of a β-trifluoroacetoxy group generally proceeds more rapidly and with more varied regiochemistry than its less electronegative counterparts, this reaction was studied
in the hope of understanding more about the subtleties of the mechanism of the β- acyloxyalkyl radical rearrangement. The mechanism of the catalysed rearrangement of Nalkoxy-
2(1H)-pyridinethiones was also explored because preliminary studies indicated that the transition state (TS) for this process was isoelectronic with TSs postulated for the β-acyloxyalkyl radical and other novel rearrangements.
¶
A kinetic study of the rearrangement of the 2-methyl-2-trifluoroacetoxy-1-heptyl
radical in solvents of different polarity was undertaken using a radical clock method. Arrhenius equations for the rearrangement in each solvent were: hexane, log10[kr (s-1)] =
11.8±0.3 – (48.9±0.7)/ θ; benzene, log10[kr (s-1)] = 12.0±0.2 – (43.7±0.8)/ θ; and
propionitrile, log10[kr (s-1)] = 11.9±0.2 – (42.0±0.3)/ θ. Rate constants at 75˚C were:
hexane, kr = 2.9 × 104; benzene, kr = 2.8 × 105; and propionitrile, kr = 4.0 × 105 s-1.
The equilibrium constant for the reversible rearrangement at 80°C in benzene was 15.1
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Danielsson, Mathias. "Spectroscopic study of titanium monohydride and storage ring experiments." Doctoral thesis, Stockholm : Physics Department, Stockholm University, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-7451.
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Kazi, Suraya. "Electric Transport of Rare-earth Metal Oxy-hydride Thin Films." Thesis, Uppsala universitet, Materialfysik, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-440954.
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In this project, I investigate the photoconductivenature of photochromic rare-earth metal oxy hydrides (REMHO). Such materials have received increasingscientific attention since they show a color-neutralphotochromic effect that can be applied, e.g., in smartwindows or chromogenic devices. Photochromicmaterials reversibly turn opaque from transparentunder illumination with light of optical wavelength. Inrecent studies it was found that these materials alsoshow an instant decrease in resistivity whenilluminated which can be used in optical sensors. Tounderstand the nature of this photoconductive effect,I grew yttrium oxy hydride thin films by reactivemagnetron sputtering. I measured the resistivity forillumination from front and substrate side, opticaltransmission and compositions of the samples andrelated the results to photoconductivity. I show thatphotoconductivity is a bulk effect and not directlyrelated to photochromism. Samples that almost lostphotochromism due to aging, still show strongphotoconductivity. Moreover, it was observed that theresistance increased faster during bleaching for frontillumination than for back illumination.
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Melle-Franco, Manuel. "Computer simulation of ionic solids of technological interest." Thesis, University of Kent, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.327447.
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Aracheloff, Camille. "An in-situ study of the controlled oxidation of yttrium hydride thin films." Thesis, Uppsala universitet, Tillämpad kärnfysik, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-417762.
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Miniotas, Andrius. "Synthesis and Characterization of Magnetoresistive Thin Film Oxides and Hydrides." Doctoral thesis, Stockholm : Tekniska högsk, 2001. http://media.lib.kth.se:8080/kthdisseng.html.
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Pan, Yi. "Formation of Superhexagonal Chromium Hydride by Exposure of Chromium Thin Film to High Temperature, High Pressure Hydrogen in a Ballistic Compressor." PDXScholar, 1991. https://pdxscholar.library.pdx.edu/open_access_etds/1243.
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The interaction of hydrogen with metals has great environmental significance in problems ranging from the catastrophic failure of materials due to hydrogen embrittlement to safe and efficient storage of hydrogen as a metal hydride. Chromium (Cr) is widely used as an alloying agent to produce materials such as stainless steel and as an electroplated coating on materials to prevent corrosion and to minimize wear. Hydrogen which co-deposits with chromium during electroplating forms hexagonal close packed CrH or face centered cubic CrH2 which cracks the deposit. The behavior of hydrogen in Cr, especially the crystal structure modifications of metal Cr when it is exposed to hot, dense hydrogen gas is not completely understood. In equilibrium study, chromium hydride has been found of hexagonal close packed structure under 400 °C with high hydrogen pressure. Experiments at higher temperatures are limited by the equipment and technology. This dissertation describes a novel, non-equilibrium method which was used to synthesize a new chromium hydride phase. Single crystal, body centered cubic Cr thin films were prepared by vacuum evaporation. These films were exposed to high temperature (close to the melting point of Cr), high pressure hydrogen gas in a ballistic compressor. This was followed by rapid cooling (>105 ˚C/s) to room temperature. Using the transmission electron microscope (TEM), second phase particles of superhexagonal structure, which has lattice constant A=4.77Å and C/A=1.84, are found in the films. This structure has a volume per Cr atom slightly larger than that of hexagonal closed packed CrH, so that the superhexagonal structure may contain more hydrogen than the hexagonal close packed CrH. The superhexagonal particles have a definite orientation relationship with the matrix: [021][subscript sh] II [OOl][subscript b] and (212)[subscript sh] II (IIO)[subscript ]b. The superhexagonal structure is quite stable in air and at room temperature, but decomposes to body centered cubic Cr when heated by the electron beam illumination in the TEM. No such particles were observed in Cr films exposed to pure argon under similar conditions in the ballistic compressor. Positive identification of hydrogen content was obtained by high-temperature vacuum extraction in a discharge tube. After vacuum extraction, hydrogen spectrum was observed, and the intensity of electron diffraction from superhexagonal structure decreased. Using an energy dispersive spectrometer with the capability of detecting elements down to atomic number six (carbon), no changes in composition of the films were found by comparing the characteristic x-ray spectra of the same film before and after exposure to hot, dense hydrogen in the ballistic compressor. This result suggests that this non-equilibrium method may be used for other metal-hydrogen systems to obtain new structural phases that are of scientific or technological interest.
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Bliersbach, Andreas. "Hydrogen diffusion in nano-sized materials : investigated by direct imaging." Thesis, Uppsala universitet, Materialfysik, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-156033.
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The kinetics of interstitial hydrogen are of great interest and importance for metal-hydride storage, purification, fusion and fission reactor technology, material failure processes, optical sensors for hydrogen gas and many other technologies. In particular nano-sized materials motivate fascinating applications and scientific questions. If hydrogen is absorbed in vanadium it alters the band structure around the Fermi energy. These modifications of the band structurelead to a change in the absorptance of vanadium which are in first order approximation proportional to the concentration. We present a methodto quantify chemical diffusion of hydrogen in nano-sized materials.The induced changes in the absorptance of vanadium hydride (VHx) thin-films are observed visually and in real-time as a function of position.Concentration profiles and their evolution in time, during chemicaldiffusion, were measured down to a hydrogen content corresponding tojust a few effective monolayers, randomly distributed within VHx. For concentrations reached via phase transitions distinct diffusional behavior was found, where a diffusion-front, a strong concentration gradient, migrates in the direction of the diffusive hydrogen flux. The results show that decreased size strongly influences the energy landscape and reveal different rate limiting steps for absorption and desorption.
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Chen, James. "In-situ study of the chemical composition of photochromic Yttrium Oxy-Hydrides thin films." Thesis, Uppsala universitet, Tillämpad kärnfysik, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-389390.
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Ozgit, Cagla. "Isochronal Hydrogenation Of Textured Magnesium/palladium Thin Films." Master's thesis, METU, 2009. http://etd.lib.metu.edu.tr/upload/12610385/index.pdf.
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Pure and palladium‐
covered 350 nm thick magnesium thin films were deposited on glass substrates via thermal evaporation. In the as&
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deposited state, films were highly textured with Mg (001) parallel to the substrate. Hydrogen loading experiments were carried out in two different conditions
namely isothermal and isochronal. Hydrogenation behaviors of the thin films were followed by twopoint probe electrical resistance and optical transmittance measurements, as well as x&
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ray diffraction studies. Isothermal hydrogenation experiments conducted on Pd&
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covered Mg thin films have revealed that these films can absorb hydrogen at temperatures starting from 333 K, producing MgH2 with a random texture. When the films were heated slowly starting from the room temperature, on the other hand, hydrogenation gives rise to a textured MgH2, where (110) parallel to the substrate with a minor (101) component. Formation of the textured hydride in isochronal loading was discussed within the context of lattice mismatch in Mg to MgH2 transformation. It was further shown that formation of such a textured hydride in Mg thin films minimizes in&
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plane lattice distortion.
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Aðalsteinsson, Sigurbjörn Már. "A study of the photochromic effect in oxygen containing rare-earth metal hydride thin films and multilayer structures." Thesis, Uppsala universitet, Tillämpad kärnfysik, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-418111.
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In this work, we have studied the photochromic response of several oxygen containing rare-earth hydride thin films (REHO, RE = Y, Nd, Gd, and Dy). Their chemical composition was characterized by an iterative multi-method approach based on ion beams, while the photochromic effect was measured by means of optical spectrometry. We report photochromic responses for YHO, NdHO, GdHO and DyHO of several thicknesses but averaged chemical compositions described by the formula REH2-δOδ; in the range of 0.45 < δ < 1.5 (δ being the [O]/[RE] ratio). Possible side-effects of the ambient conditions on the photochromic effect in YHO thin films were investigated by comparing the optical properties (photochromic response and bleaching) of YHO films capped with two different diffusion barrier layers (Al2O3 and Si3N4) to their respective uncapped sample. The ambient atmosphere was found to play no significant role in the photochromic effect. In sequence, identical YHO thin films were prepared on three different (transparent) substrates (i.e., soda lime glass, CaF2, and Al2O3 as buffer layer). The effect of substrate induced stress in the YHO thin films was investigated in details and no significant correlation between the substrate and photochromic effect was observed. Finally, isotope labeling in double layers of YHO and YDO was done to investigate possible diffusion of hydrogen/deuterium within the REHO layers. No diffusion of hydrogen/deuterium could be observed in the double layered structure during a one-week period and one illumination/bleaching cycle.
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Bouilly, Guillaume Jacques. "Synthesis and characterization of transition metal oxides and oxyhydrides using epitaxial thin films deposition." 京都大学 (Kyoto University), 2015. http://hdl.handle.net/2433/200450.
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Bonelli, Giulio. "Electrochemical loading of hydrogen in Mg thin films." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2021. http://amslaurea.unibo.it/22351/.
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The science and technology of hydrogen production from renewable energy, hydrogen sensing and hydrogen storage are central to the realization of a hydrogen-based society, in which me may be living one day.
The focus of my Master thesis will be the solid-state hydrogen storage in nanostructured metallic hydrides. In fact, beside the physical storage of hydrogen through pressurized tanks, it is also possible to store hydrogen in the chemical bonds of the metallic hydrides such as MgH2, LaNi5H6,FeTiH2, just to name a few. The problem is to achieve these goals at temperature and pressure as close as possible to ambient conditions. Knowledge-based design of advanced materials can help to solve issues related to unfavourable kinetics and thermodynamics of hydrogen storage. In particular, size effects and interface engineering in nanomaterials are exciting tools to modify and improving hydrogen sorption properties beyond the current state of the art. This is the subject of the present project.
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Mensinger, Zachary Lee 1982. "Synthesis and characterization of tridecameric Group 13 hydroxide clusters." Thesis, University of Oregon, 2010. http://hdl.handle.net/1794/11300.
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xx, 153 p. : ill. (some col.) A print copy of this thesis is available through the UO Libraries. Search the library catalog for the location and call number.In the research area of Group 13 hydroxide clusters, progress is often hampered by difficult and inefficient synthetic procedures. This has greatly limited the numerous potential applications of Group 13 hydroxide compounds, many of which require large amounts of material. Most relevant to this dissertation is their application as precursors for high quality amorphous metal oxide thin films. Addressing this issue, this dissertation presents a series of Group 13 containing hydroxide compounds of general formula [M 13 (μ 3 -OH) 6 (μ-OH) 18 (H 2 O) 24 ](NO 3 ) 15 which are generated through an efficient, scalable synthetic procedure. Throughout this dissertation, the compounds are generally referred to by their metal content, i.e. [Ga 13 (μ 3 -OH) 6 (μ-OH) 18 (H 2 O) 24 ](NO 3 ) 15 is designated as Ga 13 . Chapter I reviews the literature of inorganic and ligand-supported Group 13 hydroxide compounds with the aim of identifying common structural trends in metal composition and coordinating ligands. This summary is limited to clusters of aluminum, gallium, and indium. Chapter II describes in detail the synthesis and characterization of one such cluster, Al 13 . Following this in Chapter III is the description of the first heterometallic Group 13 hydroxide compound, Ga 7 In 6 , which along with Ga 13 was used as a precursor material for metal oxide thin films in collaboration with Professor Doug Keszler at Oregon State University. Chapter IV describes a series of six Ga/In compounds, as well as two Al/In compounds. Included in this chapter is an analysis of the heat-induced decomposition properties of the Ga/In clusters. Understanding such thermal decomposition is particularly relevant for the use of these compounds as precursor materials, as an annealing step is used to condense the films. Chapter V addresses the potential for post-synthetic modification of the compounds through metal and ligand exchange reactions, an area that also addresses the issue of solution stability of the structures Chapter VI describes the synthesis and characterization of related Group 13 compounds, including two infinite chain structures and additional heterometallic compounds. Lastly, Chapter VII concludes this dissertation and discusses potential areas of future research. This dissertation includes co-authored material and previously published results.
Committee in charge: Victoria DeRose, Chairperson, Chemistry; Darren Johnson, Member, Chemistry; James Hutchison, Member, Chemistry; Michael Haley, Member, Chemistry; Raghuveer Parthasarathy, Outside Member, Physics
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RIBEIRO, VILMARIA A. "Estudo da preparação de eletrocatalisadores Pt-Sn/C por meio da deposição superficial de Pt sobre Sn/C utilizando diferentes metodologias para aplicação na oxidação eletroquímica do etanol." reponame:Repositório Institucional do IPEN, 2015. http://repositorio.ipen.br:8080/xmlui/handle/123456789/25304.
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Tese (Doutorado em Tecnologia Nuclear)
IPEN/T
Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP
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Trotochaud, Lena. "Structure-Composition-Activity Relationships in Transition-Metal Oxide and Oxyhydroxide Oxygen-Evolution Electrocatalysts." Thesis, University of Oregon, 2014. http://hdl.handle.net/1794/18312.
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Solar water-splitting is a potentially transformative renewable energy technology. Slow kinetics of the oxygen evolution reaction (OER) limit the efficiency of solar-water-splitting devices, thus constituting a hurdle to widespread implementation of this technology. Catalysts must be stable under highly oxidizing conditions in aqueous electrolyte and minimally absorb light. A grand goal of OER catalysis research is the design of new materials with higher efficiencies enabled by comprehensive understanding of the fundamental chemistry behind catalyst activity. However, little progress has been made towards this goal to date.
This dissertation details work addressing major challenges in the field of OER catalysis. Chapter I introduces the current state-of-the-art and challenges in the field. Chapter II highlights work using ultra-thin films as a platform for fundamental study and comparison of catalyst activity. Key results of this work are (1) the identification of a Ni0.9Fe0.1OOH catalyst displaying the highest OER activity in base to date and (2) that in base, many transition-metal oxides transform to layered oxyhydroxide materials which are the active catalysts. The latter result is critical in the context of understanding structure-activity relationships in OER catalysts. Chapter III explores the optical properties of these catalysts, using in situ spectroelectrochemistry to quantify their optical absorption. A new figure-of-merit for catalyst performance is developed which considers both optical and kinetic losses due to the catalyst and describes how these factors together affect the efficiency of composite semiconductor/catalyst photoanodes. In Chapter IV, the fundamental structure-composition-activity relationships in Ni1-xFexOOH catalysts are systematically investigated. This work shows that nearly all previous studies of Ni-based catalysts were likely affected by the presence of Fe impurities, a realization which holds significant weight for future study of Ni-based catalyst materials. Chapter V discusses the synthesis of tin-titanium oxide nanoparticles with tunable lattice constants. These materials could be used to make high-surface-area supports for thin layers of OER catalysts, which is important for maximizing catalyst surface area, minimizing the use of precious-metal catalysts, and optimizing 3D structure for enhanced mass/bubble transport. Finally, Chapter VI summarizes this work and outlines directions for future research.
This work contains previously published and unpublished co-authored material.2015-03-29
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Fajardo, Gabriela Isabel. "Physical and Chemical Soil Properties of Ten Virginia Department of Transportation (VDOT) Mitigation Wetlands." Thesis, Virginia Tech, 2006. http://hdl.handle.net/10919/31304.
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In 1998, the Virginia Department of Transportation (VDOT) adopted standards for soil handling and amendments to improve created non-tidal wetland soil conditions. This study was conducted in sites where these new reconstruction practices were supposedly being implemented. Specific objectives were (i) to determine the relative effects of soil reconstruction practices on mitigation site soils, (ii) to assess the degree to which hydric soil indicators were present, and (iii) to evaluate the relative edaphic potential of mitigation site soils. Soil physical, chemical and morphological properties were analyzed in ten mitigation wetlands located in Virginiaâ s Piedmont and Coastal Plain. Surface soil pH was high due to liming, although some sites demonstrated low subsoil pH, indicating the presence of sulfidic materials. Nutrient levels varied, while C:N ratios were low (<25:1), suggesting a high quality organic matter complex. Organic amendments were generally applied at a rate of 4% soil organic matter content. Actual measured carbon content was <2.6% (<50 Mg ha-1). Sites not receiving organic materials and associated tillage had root-limiting bulk densities at the surface, while the majority of sites had root-limiting subsoil (30 cm) bulk densities due to weakly developed soil structure and a lack of deep ripping practices. Many sites also contained high sand content (>50%), which may negatively affect other soil properties. Nine sites had confirmed Hydric Soil Indicators, with their occurrence in a site as high as 70%. Soil reconstruction methods need to incorporate higher organic amendment rates and/or routine disking/ripping practices to improve mitigation wetland soil conditions.Master of Science
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Hoda, Sadat Emami Meibody. "Influence de la substitution du nickel sur les propriétés d’hydrogénation de TiNi pour des applications d’alliage à mémoire de forme et de batteries NiMH." Thesis, Paris Est, 2012. http://www.theses.fr/2012PEST1137.
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Cette thèse vise à améliorer les propriétés d'alliage à mémoire de forme et de stockage d'hydrogène du TiNi par des substitutions chimiques sur le sous-réseau de Ni. L'effet de la substitution de Ni par Pd, Cu et Co sur les propriétés structurales, la transformation martensitique et les propriétés d'hydrogénation de TiNi, a été étudiée par des techniques structurales (diffraction des Rayons-X et des neutrons sur poudre), calorimétriques, par réaction solide-gaz et par mesure électrochimique. Des calculs de type DFT ont été effectués pour mettre en évidence les modifications de la structure électronique sur les propriétés d'hydrogénation. Les trois substitutions, TiNi1-zMz (M = Pd, Cu et Co; z ≤ 0,5), conduisent à la formation de composés pseudo-binaires. La substitution par Pd et par Cu augmentent le volume de la maille de TiNi, alors que celle par Co possède un effet inverse. Les températures de transformation martensitique suivent la même tendance que les changements de volume. Ils augmentent fortement pour M = Pd et légèrement pour M = Cu, tandis qu'elles diminuent pour M = Co. Les propriétés d'hydrogénation sont très sensibles à la nature chimique des substitutions. La capacité diminue fortement avec la substitution par Pd, modérément avec le Cu et reste stable pour le M = Co. Contrairement à l'effet attendu par des considérations géométrique, la substitution par Pd et par Cu diminuent la stabilité des hydrures. Les calculs DFT montrent qu'un effet électronique, et non géométrique, régit la stabilité des hydrures pour M = Pd. La substitution par le cobalt induit une formation de plusieurs hydrures par étapes successives, observée par mesure d'isothermes pression-composition en multiple plateaux. Pour les applications, la substitution de Ni par Cu avec une faible teneur (z = 0,2) augmente la capacité de décharge électrochimique de TiNi de 150 à 300 mAh/g en raison de la déstabilisation de l'hydrure. Cela ouvre de nouvelles perspectives pour l'utilisation d'alliages TiNi comme électrodes de batteries Ni-MH. En revanche, la substitution par Pd ou Cu (avec z = 0,5) est très efficace pour réduire la réactivité de TiNi avec l'hydrogène, et est donc intéressante pour des applications à mémoire de forme sous un environnement réducteurThe PhD thesis aims to improve shape memory and hydrogen storage properties of TiNi by chemical substitutions in the Ni sub-lattice. The effect of Pd, Cu and Co substitutions on crystal structure, martensitic transformation and hydrogenation properties of TiNi has been studied by structural (X-ray and neutron powder diffraction), calorimetric, solid-gas and electrochemical means. Ab initio DFT calculations were done to highlight electronic effects on hydrogenation properties. The three substitutions, TiNi1-zMz (M = Pd, Cu and Co; z ≤ 0.5), lead to the formation of pseudobinary compounds. Substitutions by Pd and Cu increase the unit-cell volume of TiNi, whereas the reverse effect occurs for Co. Martensitic transformation temperatures correlate with volume variations. They increase strongly for M = Pd and slightly for M = Cu, whereas M = Co decreases it. Hydrogenation properties are very sensitive to chemical elements substitution. The capacity decreases strongly for M = Pd, moderately for M = Cu and remains stable for M = Co. Contrary to expected effect by geometric model, both Pd and Cu substitutions decrease the stability of hydrides. DFT calculations show that electronic rather than geometric effects govern hydride stability for M = Pd. Co substitution induces step-wise formation of hydrides with a multi-plateau behaviour in pressure-composition isotherms. As concerns applications, low amount of Cu substitution (z =0.2) increases the electrochemical discharge capacity of TiNi from 150 to 300 mAh/g due to hydride destabilization. This opens new perspectives for using TiNi-based alloys in Ni-MH batteries. In contrast, Pd and high amount of Cu substitution (z = 0.5) are effective to decrease TiNi reactivity towards hydrogen, and therefore attractive for shape memory applications under reductive environment
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Porte, Agnès. "Determination des parametres qui regissent la cinetique et la composition d'un depot de gainas/inp par la methode aux hydrures." Clermont-Ferrand 2, 1988. http://www.theses.fr/1988CLF2D162.
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En s'appuyant sur les resultats experimentaux de la croissance de ga::(x)in::(1-x)as/inp en phase vpeur par la methode aux hydrures et sur une theorie cinetique de croisssance qui permet d'exprimer facilement le rapport des pressions partielles de chlorures en fonction de x, detection et analyse de differents phenomenes en jeu dans la croissance. Calcul des parametres necessaires a la prise en compte de ces phenomenes pour la determination des pressions partielles reelles de chacun des constituants de la phase vapeur dans chaque experience realisee. La maitrise de la cinetique du depot et de la composition de la couche de ga::(x)in::(1-x)as est de ce fait rendue possible dans l'epitaxie par la methode aux hydrures
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Ayturk, Mahmut Engin. "Synthesis, annealing strategies and in-situ characterization of thermally stable composite thin Pd/Ag alloy membranes for hydrogen separation." Worcester, Mass. : Worcester Polytechnic Institute, 2007. http://www.wpi.edu/Pubs/ETD/Available/etd-042307-012951/.
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Thesis (Ph.D.)--Worcester Polytechnic Institute.Keywords: composite Pd and Pd/Ag membranes, alloying, Pd/Ag barrier, intermetallic diffusion, bi-metal multi-layer BMML deposition, electroless plating kinetics, high temperature x-ray diffraction, aluminum hydroxide surface grading, porous sintered metal supports, hydrogen separation. Includes bibliographical references (leaves 279-296 ).
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Schuttler, Armin. "Influencing factors on aromatic typicality of wines from Vitis vinifera L. cv. Riesling – sensory, chemical and viticultural insights." Thesis, Bordeaux 2, 2012. http://www.theses.fr/2012BOR22019/document.
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L’espace sensoriel des vins secs de Riesling a été établi en utilisant diverses méthodologies d’analyse sensorielle. Cela a été possible grâce à la comparaison avec des vins blancs secs de styles différents, en particulier avec des vins blancs secs de Bordeaux montrant une caractéristique aromatique forte du Sauvignon blanc. Deux panels d’experts, l’un en France, l’autre en Allemagne ont démontré que la typicité aromatique des vins Riesling est particulièrement associée à des descripteurs fruités comme les notes d’agrume et de fruits jaunes. Des corrélations ont aussi été établies entre les données sensorielles et l’analyse quantitative des composés volatils déterminés par chromatographie en phase gazeuse couplée à la spectrométrie de masse (CG-SM). En particulier, pour la première fois, il a été possible de démontrer que les teneurs en 3 sulfanylhexan 1-ol (3SH) sont significativement corrélées avec le jugement de typicité des vins de Riesling. Ensuite, l’impact de conditions viticoles (régime hydrique de la vigne, pratique de l’effeuillage) pendant la période végétative a été mesuré vis à vis des teneurs en précurseurs d’arômes des raisins et des moûts ainsi que pour des composants aromatiques des vins. Ainsi, les concentrations en composés volatils tels que le 3SH, le linalol et le 1,1,6-trimethyl-1,2-dihydronaphthalene (TDN) dans les vins sont évidemment influencées par des facteurs viticoles. Par ailleurs, dans une démarche de caractérisation de composés de l’arôme des vins de Riesling, un composé bien connu, le trans-cinnamate d’éthyle, a été identifié comme étant susceptible d’influencer l’arôme des vins et d’être impliqué dans la perception de leur typicité aromatique. La méthodologie appliquée pour arriver à ce résultat, a intégré à la fois le fractionnement par chromatographie en phase liquide de haute performance (CLHP) en associant une approche sensorielle comparative entre les extraits de vins Riesling et ceux de vins blancs secs de Bordeaux, puis la chromatographie en phase gazeuse en deux dimensions en mode de détection par olfactométrie et spectrométrie de masse de haute résolution (2D-CG-O-HRMS). Le couplage de ces deux approches a permis de constituer des outils suffisamment pertinents pour décrypter l’arôme du Riesling. L’ensemble de ces résultats a permis d’accroitre nos connaissances sur l’expression aromatique des vins de Riesling et les composés aromatiques impliqués ainsi que sur l’impact des conditions viticolesThe sensory concept of typicality of dry Riesling wines was demonstrated using different sensory analysis methodologies. This was achieved by comparison to other styles of dry white wines especially from Bordeaux, which showed strong Sauvignon blanc character. ‘Fruity’ descriptors like ‘citrus fruit’ and ‘yellow fruit’ were shown to be related to dry Riesling wines’ typicality independently by two panels of wine experts. Analysis of volatiles by means of gas chromatography coupled to mass selective detection (GC-MSD) was realised in order to link sensory data to aroma compounds’ concentrations. For the first time, concentrations of the high potent aroma compound 3 sulfanylhexan-1-ol (3SH) were shown to correlate with typicality ratings for Riesling wines. The impact of viticultural conditions during the grape vine growing period on finished wines’ aroma was studied with respect to grape vine water status and leaf removal practices including precursor studies in berries and must. It was clearly shown that changing viticultural conditions influenced volatile aroma compounds’ concentrations in finished wines, especially for 3SH, linalool and 1,1,6 trimethyl-1,2-dihydronaphthalene (TDN). Additionally the well-known aroma compound trans-ethyl cinnamate was identified to be a possible impacting aroma compound implicated in Riesling wines’ aromatic typicality. The applied methodology using two-dimensional gas chromatography with olfactometric and high resolution mass spectrometric detection (2D-GC-O/HRMS) after a sensory guided fractionation using high pressure liquid chromatography (HPLC) in a comparative approach to dry white wines from Bordeaux, showed to be a powerful tool to decrypt Riesling wines’ aroma. The totality of results allowed improving the knowledge on aromatic typicality of Riesling wines and the imparted aroma compounds and how those concentrations could be influenced by changing viticultural conditions
Das eigene sensorische Konzept der Typizität von trockenen Rieslingweinen wurde mittels unterschiedlicher sensorischer Methoden nachgewiesen. Dies wurde insbesondere durch den Vergleich mit trockenen Weißweinen anderer Stile, vornehmlich mit trockenen Weißweinen aus Bordeaux, welche eine ausgeprägte Sauvignon blanc Stilistik aufwiesen, erzielt. Es konnte mithilfe von zwei unabhängigen sensorischen Panels, bestehend aus Weinexperten, gezeigt werden, dass die aromatische Typizität von trockenen Rieslingweinen mit „fruchtigen“ Deskriptoren, wie „Zitrus“ oder „gelbe Früchte“ zusammenhängt. Die mittels Gaschromatographie, gekoppelt mit massenspektrometrischer Detektion, (GC-MSD) gemessenen Konzentrationen flüchtiger Verbindungen wurden mit den sensorischen Daten korreliert. Hierbei wurde zum ersten Mal gezeigt, dass die Konzentrationen des hoch potenten Aromastoffes 3 Sulfanylhexanol (3SH) mit der wahrgenommenen Typizität von Rieslingweinen im engen Zusammenhang stehen. Der Einfluss weinbaulicher Bedingungen während der vegetativen Phase auf das Aroma von Weinen, einschließlich der Aromastoffvorstufen in Beeren und Most, wurde hinsichtlich der Wasserversorgung der Rebe und verschiedener Entblätterungspraktiken untersucht. Es konnte gezeigt werden, dass sich ändernde weinbauliche Bedingungen die Gehalte von Aromastoffen in den Weinen beeinflussen, insbesondere die von 3SH, Linalool und 1,1,6 Trimethyl-1,2-dihydronaphthalene (TDN). Zusätzlich hierzu wurde der Aromastoff trans-Zimtsäureethylester als möglicher beteiligter Aromastoff in der Wahrnehmung der aromatischen Typizität in Rieslingweinen identifiziert. Der hierzu angewandte vergleichende Ansatz mit trockenen Weißweinen aus Bordeaux unter Verwendung einer sensorisch geleiteten Fraktionierung mittels Hochdruck-Flüssigkeits-Chromatographie (HPLC) und anschließender zweidimensionalen Gaschromatographie gekoppelt mit olfaktorischer und hochauflösender massenspektrometrischer Detektion erwies sich als sehr gut geeignetes Werkzeug zur Dechiffrierung des Aromas von Rieslingweinen. Die Gesamtheit der Ergebnisse ermöglichte es das Wissen über die aromatische Typizität von Rieslingweinen und die beteiligten Aromastoffe zu erweitern, und einen Einblick zu bekommen wie diese Konzentrationen durch weinbauliche Faktoren beeinflusst werden
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Muradás, Rodrigo Ricabone. "Mecano-síntese e caracterização de ligas de Ti-Nb-Sn." UNIVERSIDADE ESTADUAL DE PONTA GROSSA, 2006. http://tede2.uepg.br/jspui/handle/prefix/1409.
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Previous issue date: 2006-10-31Mechanical alloying is a powder processing technique involving cold welding, fracturing mechanisms and rewelding of powder particles in a ball mill. The present work applied this technique with the purpose of processing titanium, niobium and tin alloys, through planetary ball mill and attritor mill. The atomic percentages of these elements were varied in six differents ways. The niobium hydrate was used on production of some alloys in study, with the purpose to observe the effects during the milling and on the alloys obtained after sintering. Differences between processing in planetary ball mill and attritor mill, as well the cold welding influences on the kinetic parameters of milling process were approached. The use of niobium hydrate result in a decrease of powders average crystallite size, and an increase of micro hardness of sintered alloys. This work obtained beta titanium alloys and alpha-beta titanium alloys in namometric sizes. The average crystallite size, for milled powders, was 7,6 nm.
Mecano-síntese é uma técnica de processamento em pó que envolve a soldagem a frio, mecanismos de fratura e a resoldagem das partículas de pós, em moinhos de bolas. O presente trabalho utilizou esta técnica com o propósito de processar ligas de titânio, nióbio e estanho, através de moinhos de bolas planetário e de atrito. As porcentagens atômicas destes elementos foram variadas de seis maneiras diferentes. O hidreto de nióbio foi utilizado na produção de algumas ligas em estudo, com o propósito de se observar os efeitos durante a moagem e na liga obtida após a sinterização. Diferenças entre o processamento em moinho de bolas planetário e o moinho de atrito, assim como as influências da soldagem a frio nos parâmetros cinéticos do processo de moagem, foram abordadas. O uso do hidreto de nióbio resultou na diminuição do tamanho médio de cristalito dos pós, e em um acréscimo na microdureza das ligas sinterizadas. Neste trabalho foram obtidas ligas de titânio beta e de titânio alfa-beta, em tamanhos nanométricos. O tamanho médio do cristalito, para os pós moídos, foi de 7,6 nm.
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Forano, Claude. "Les conducteurs protoniques : HSbO3.nH2O ET SnO2.nH2O : caracterisation, etude rmn et applications." Clermont-Ferrand 2, 1987. http://www.theses.fr/1987CLF21069.
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Preparation par une methode sol-gel permettant d'obtenir des materiaux de grande purete; mise en evidence de differences structurales importantes, d'une tres grande homogeneite morphologique et d'une difference importante de la taille des cristallites. Confirmation par rmn de l'existence de plusieurs especes protonees. Etude des variations de la conductivite en fonction de la temperature; influence de la teneur en eau. Mise en evidence de la relation entre la conductivite electrique et la mobilite protonique a partir de mesures des temps de relaxation et proposition d'un mecanisme de type grotthus. Elaboration de couches epaisses par serigraphie; possibilites d'application dans des dispositifs microioniques. Essais d'utilisation pour la detection de h::(2)
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Lin, Shuai-Ju, and 林帥儒. "Determination of tin and arsenic in pure copper by flow injection hydride generation atomic absorption spectrometry." Thesis, 2003. http://ndltd.ncl.edu.tw/handle/18992299755086505728.
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碩士靜宜大學
應用化學研究所
91
In this research, the flow injection hydride generation atomic absorption spectrometry (FIAS-HGAAS) for the determinations of tin and arsenic in pure copper were developed. Complex matrices made the analysis difficult because pure copper was composed of numerous metals and non-metals. An effective pretreatment was developed in this work. With the pretreatment and the optimum experimental conditions, reliable results were obtained. Serious matrix effect was observed when tin and arsenic in pure copper were determined by FIAS-HGAAS. By using cupferron-extraction as the pretreatment to separate the analyte from copper matrix in sample solution could reduce the interference. Furthermore, chloroform which was used for extraction also caused severe background absorption. The residual chloroform in aqueous phase was removed by heating to avoid the interference. For tin, the determination was done at 224.6 nm. The reductant solution was 0.8% NaBH4 and carrier solution was saturated boric acid in 1% HCl. Thus, stannane was generated. The linear range was 1~13 ppb, detection limit was 0.25 ppb and recovery was 93.7%. For arsenic, the detection wavelength used was 193.7 nm. The reductant solution was 0.4% NaBH4 and carrier solution was 10% HCl used for generate arsine. The linear range was 1~20 ppb, detection limit was 0.26 ppb and recovery was 93.0%. Both quantitative results were closed to certified value. The relative error was 5.13% for tin. The R.S.D. for tin and arsenic was 4.15% and 5.70%, respectively. The proposed methods gave accurate and precise results.
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Seok, Moonki Krafft Marie E. "Tin(IV) hydride-mediated intramolecular reductive head-to-tail Michael reaction of enones with activated alkene tethers." Diss., 2006. http://etd.lib.fsu.edu/theses/available/etd-04112006-001230.
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Thesis (M.S.)--Florida State University, 2006.Advisor: Marie E. Krafft, Florida State University, College of Arts and Sciences, Dept. of Chemistry and Biochemistry. Title and description from dissertation home page (viewed June 13, 2006). Document formatted into pages; contains xix, 119 pages. Includes bibliographical references.
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"Epitaxy of group IV optical materials and synthesis of IV/III-V semiconductor analogs by designer hydride chemistries." Doctoral diss., 2013. http://hdl.handle.net/2286/R.I.18073.
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abstract: The thesis studies new methods to fabricate optoelectronic Ge1-ySny/Si(100) alloys and investigate their photoluminescence (PL) properties for possible applications in Si-based photonics including IR lasers. The work initially investigated the origin of the difference between the PL spectrum of bulk Ge, dominated by indirect gap emission, and the PL spectrum of Ge-on-Si films, dominated by direct gap emission. It was found that the difference is due to the supression of self-absorption effects in Ge films, combined with a deviation from quasi-equilibrium conditions in the conduction band of undoped films. The latter is confirmed by a model suggesting that the deviation is caused by the shorter recombination lifetime in the films relative to bulk Ge. The knowledge acquired from this work was then utilized to study the PL properties of n-type Ge1-ySny/Si (y=0.004-0.04) samples grown via chemical vapor deposition of Ge2H6/SnD4/P(GeH3)3. It was found that the emission intensity (I) of these samples is at least 10x stronger than observed in un-doped counterparts and that the Idir/Iind ratio of direct over indirect gap emission increases for high-Sn contents due to the reduced gamma-L valley separation, as expected. Next the PL investigation was expanded to samples with y=0.05-0.09 grown via a new method using the more reactive Ge3H8 in place of Ge2H6. Optical quality, 1-um thick Ge1-ySny/Si(100) layers were produced using Ge3H10/SnD4 and found to exhibit strong, tunable PL near the threshold of the direct-indirect bandgap crossover. A byproduct of this study was the development of an enhanced process to produce Ge3H8, Ge4H10, and Ge5H12 analogs for application in ultra-low temperature deposition of Group-IV semiconductors. The thesis also studies synthesis routes of an entirely new class of semiconductor compounds and alloys described by Si5-2y(III-V)y (III=Al, V= As, P) comprising of specifically designed diamond-like structures based on a Si parent lattice incorporating isolated III-V units. The common theme of the two thesis topics is the development of new mono-crystalline materials on ubiquitous silicon platforms with the objective of enhancing the optoelectronic performance of Si and Ge semiconductors, potentially leading to the design of next generation optical devices including lasers, detectors and solar cells.Dissertation/Thesis
Ph.D. Chemistry 2013
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HSUAN, CHANG PIN, and 張品軒. "A Study on the Determination of Selenium, Bismuth and Tin in Pure Copper by Flow Injection Hydride Generation Atomic Absorption Spectrometry." Thesis, 2000. http://ndltd.ncl.edu.tw/handle/60176460534579488845.
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Pineda, Cedeno Leslie William. "Germanium-, Tin-, Lead-, and Bismuth-Containing β-Diketiminato Complexes for the Synthesis and Structural Characterization of Hydroxide, Carboxylic Acid, Heterobimetallic Oxide, Transition Metal-Main Group, Hydride and Halide Compounds." Doctoral thesis, 2006. http://hdl.handle.net/11858/00-1735-0000-0006-B0D1-0.
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Pineda, Cedeño Leslie William [Verfasser]. "Germanium-, tin-, lead-, and bismuth-containing β-diketiminato [beta-diketiminato] complexes for the synthesis and structural characterization of hydroxide, carboxylic acid, heterobimetallic oxide, transition metal-main group, hydride and halide compounds / vorgelegt von Leslie William Pineda Cedeño." 2006. http://d-nb.info/982145101/34.
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Hamm, Magnus. "Hydrogen diffusion and hydride formation in grain boundary rich magnesium." Doctoral thesis, 2018. http://hdl.handle.net/11858/00-1735-0000-002E-E621-7.
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HSiang, Wen Hui, and 項文慧. "Growth of GaN thin films on Pattern Sapphire substrates by Hydride vapor phase epitaxy." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/36709243673246140597.
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碩士國立中山大學
材料與光電科學學系研究所
102
In this thesis, the growth of c-plane gallium nitride (GaN) epitaxial films on a patterned sapphire substrate (PSS) by hydride vapor phase epitaxy (HVPE). Gallium chloride (GaCl) formed by the reaction of high purity gallium metal and hydrogen chloride (HCl). GaCl and ammonia (NH3) were used as Ga and N sources, respectively. Nitrogen (N2) was used as carrier gas. First, the substrate was heated at 1050°C for nitridation. Then, the substrate temperature was lowered to 600°C to grow the GaN buffer layer. Finally, the substrate was heated at 1050°C again to grow of GaN films. We control the quality of films by optimizing the parameters of Ⅴ/Ⅲ ratio, growth time and substrate pre-processing. The properties of the GaN films were investigated by x-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM), photoluminescence spectra (PL), Raman spectra (Raman) and transmission electron microscopy (TEM). The results show that the crystal quality and surface morphology of GaN films are strongly related to the Ⅴ/Ⅲ ratio, growth time and substrate pre-processing. When the substrate was used in acid treatment, Ⅴ/Ⅲ ratio was 30 and growth time was 15 minutes, the growth of GaN films has an optimal condition. The XRD signal is obviously strong and full width at half maximum (FWHM) value reach a minimum at 0.15°. The SEM images show flat with continuous film morphologies, surface roughness (RMS) is about 5.164nm and thickness of film is 2µm. To further analysis of GaN epitaxial films, the photoluminescence spectra shows that the peak centered at 3.46 eV (FWHM=266 meV) and the yellow-green emission was caused by defect is minimum. The microstructural properties of GaN layer grown on a pattern sapphire substrate (PSS) shows that the crystallographic orientation relationship is [0002]GaN//[0006]PSS and [112 ̅0]GaN//[33 ̅00]PSS。
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Auer, Henry, Robin Guehne, Marko Bertmer, Sebastian Weber, Patrick Wenderoth, Thomas Christian Hansen, Jürgen Haase, and Holger Kohlmann. "Hydrides of Alkaline Earth–Tetrel (AeTt) Zintl Phases: Covalent Tt–H Bonds from Silicon to Tin." 2017. https://ul.qucosa.de/id/qucosa%3A33406.
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Zintl phases form hydrides either by incorporating hydride anions (interstitial hydrides) or by covalent bonding of H to the polyanion (polyanionic hydrides), which yields a variety of different compositions and bonding situations. Hydrides (deuterides) of SrGe, BaSi, and BaSn were prepared by hydrogenation (deuteration) of the CrB-type Zintl phases AeTt and characterized by laboratory X-ray, synchrotron, and neutron diffraction, NMR spectroscopy, and quantum-chemical calculations. SrGeD4/3–x and BaSnD4/3–x show condensed boatlike six-membered rings of Tt atoms, formed by joining three of the zigzag chains contained in the Zintl phase. These new polyanionic motifs are terminated by covalently bound H atoms with d(Ge–D) = 1.521(9) Å and d(Sn–D) = 1.858(8) Å. Additional hydride anions are located in Ae4 tetrahedra; thus, the features of both interstitial hydrides and polyanionic hydrides are represented. BaSiD2–x retains the zigzag Si chain as in the parent Zintl phase, but in the hydride (deuteride), it is terminated by H (D) atoms, thus forming a linear (SiD) chain with d(Si–D) = 1.641(5) Å.
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Liang, Huann-Jang, and 梁煥章. "Investigation on the Hydring Behaviour and Electrochemical Behaviour of Ti1-xCrxV1.6Ni0.4." Thesis, 1995. http://ndltd.ncl.edu.tw/handle/49949324792905950835.
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Yi-Chia, Lee, and 李翊嘉. "Synthesis of(α-ketoacyl)hydrido Platinum(II) Complexes and Kine- tic Studies of Olefin Insertion Reaction." Thesis, 1994. http://ndltd.ncl.edu.tw/handle/40992525114104630475.
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Swidinsky, Andrei. "Transient Electromagnetic Modelling and Imaging of Thin Resistive Structures: Applications for Gas Hydrate Assessment." Thesis, 2011. http://hdl.handle.net/1807/29520.
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Gas hydrates are a solid, ice-like mixture of water and low molecular weight hydrocarbons. They are found under the permafrost and to a far greater extent under the ocean, usually at water depths greater than 300m. Hydrates are a potential energy resource, a possible factor in climate change, and a geohazard. For these reasons, it is critical that gas hydrate deposits are quantitatively assessed so that their concentrations, locations and distributions may be established. Due to their ice-like nature, hydrates are electrically insulating. Consequently, a method which remotely detects changes in seafloor electrical conductivity, such as marine controlled source electromagnetics (CSEM), is a useful geophysical tool for marine gas hydrate exploration.
Hydrates are geometrically complex structures. Advanced electromagnetic modelling and imaging techniques are crucial for proper survey design and data interpretation. I develop a method to model thin resistive structures in conductive host media which may be useful in building approximate geological models of gas hydrate deposits using arrangements of multiple, bent sheets. I also investigate the possibility of interpreting diffusive electromagnetic data using seismic imaging techniques. To be processed in this way, such data must first be transformed into its non-diffusive, seismic-like counterpart. I examine such a transform from both an analytical and a numerical point of view, focusing on methods to overcome inherent numerical instabilities. This is the first step to applying seismic processing techniques to CSEM data to rapidly and efficiently image resistive gas hydrate structures.
The University of Toronto marine electromagnetics group has deployed a permanent marine CSEM array offshore Vancouver Island, in the framework of the NEPTUNE Canada cabled observatory, for the purposes of monitoring gas hydrate deposits. In this thesis I also propose and examine a new CSEM survey technique for gas hydrate which would make use of the stationary seafloor transmitter already on the seafloor, along with a cabled receiver array, towed from a ship. I furthermore develop a modelling algorithm to examine the electromagnetic effects of conductive borehole casings which have been proposed to be placed in the vicinity of this permanent marine CSEM array, and make preliminary recommendations about their locations.
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CHENG, CHIA-YIN, and 鄭嘉茵. "3A-Amino-3A-Deoxy-(2AS,3AS)-β-Cyclodextrin Hydrate/Tin Disulfide Modified Screen-Printed Carbon Electrode for the Electrochemical Detection of Polychlorinated Biphenyl." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/j6c6m5.
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碩士國立臺北科技大學
化學工程與生物科技系化學工程碩士班
107
Polychlorinated biphenyls (PCBs) are persistent organic pollutants which are widely distributed in the environment. It is noteworthy that PCBs are endocrine disrupting substances, and their toxicity would lead to cancer and damage mammalian reproductive system, immune system, stomach, skin, liver, etc. This study aimed to synthesize 3A-Amino-3A-Deoxy-(2AS,3AS)-β-Cyclodextrin Hydrate/tin disulfide composite material, and to study its material properties, electrochemical properties and the application on polychlorinated biphenyls (PCBs) detection. In the past, PCBs have been released into the environment due to accidents, leakage of industrial facilities and incorrect treatment methods. Therefore, the detection of PCBs is extremely important in industrial products and environmental monitoring. Electrochemical detection methods have played crucial roles in the detection of environmental pollutants in recent years, while unmodified electrodes exhibit lower conductivity and electrocatalytic activity. Therefore, those electrodes with high conductivity and electrocatalytic activity draw a lot of attentions. In the decades, metal sulfides have been widely studied due to their abundant oxidation-reduction property, higher viability, conductivity and better stability. In this study, for the detection of polychlorinated biphenyls, the nanostructured tin disulfide (SnS2) synthesized by hydrothermal technique and 3A-Amino-3A-Deoxy-(2AS,3AS)-β-Cyclodextrin Hydrate were sequentially modified onto disposable screen-printed carbon electrode (SPCE) by titration method using a micropipette. 3A-Amino-3A-Deoxy-(2AS,3AS)-β-Cyclodextrin Hydrate (β-CD) improved the selectivity of the modified electrode. X-ray diffraction analysis (XRD) and field emission scanning electron microscopy (FE-SEM) were used to analyze the structure and morphology of the materials. Cyclic voltammetry and electrochemical impedance spectroscopy were used to analyze the electrochemical performance of the β-CD /SnS2/SPCE. Further, the cyclic voltammetry and differential pulse voltammetry were carried out for the detection of PCBs changes. The detection range were 0.625~80 μM, limitation 5μM. The electrodes were stable as 88% after 7 days storage. The results showed that the β-CD successfully encapsulated PCBs to achieve an electrochemical sensor that reduced the time and increased the convenience of PCBs detection.
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Burlaka, Vladimir. "Critical thicknesses in Nb-H thin films: coherent and incoherent phase transitions, change of precipitation and growth modes and ultrahigh mechanical stress." Doctoral thesis, 2015. http://hdl.handle.net/11858/00-1735-0000-0028-87E9-A.
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Li, Xinran. "Vaccine formulation development : towards addressing major limitations of vaccines that are adjuvanted with aluminum salts." Thesis, 2013. http://hdl.handle.net/2152/28737.
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Many vaccines require an adjuvant to induce a strong immune response. Aluminum–containing adjuvants have been approved by the United States Food and Drug Administration for human use for many years. There are two main aluminum-containing adjuvants, aluminum hydroxide and aluminum phosphate. Due to their favorable safety profile, aluminum-containing adjuvants have been widely used in human vaccines for decades. Many currently licensed and commercially available vaccines contain aluminum-containing adjuvants. However, aluminum-containing vaccine adjuvants suffer from two major limiting factors: (1) aluminum-containing adjuvants can only weakly or moderately potentiate antigen-specific antibody responses and are generally considered incapable of inducing cellular immune responses; (2) vaccines that contain aluminum-containing adjuvants require cold-chain refrigeration for storage and distribution, and may not be frozen, because freezing of the vaccine in dispersion causes irreversible coagulation that damages vaccines (e.g., loss in potency and stability). In this dissertation, the first limitation was addressed by reducing the size of the aluminum hydroxide from micrometers (3-10 micrometer) to nanometers of less than 200 nm, and the second limitation mentioned above was addressed by freeze-drying vaccines that contain aluminum salts as adjuvants into a dry powder using thin-film freeze-drying. In addition, using an improved experimental design, the vaccine adjuvant activities of nanoparticles of around 200 nm was compared to that of the nanoparticles of around 700 nm. The smaller 200 nm nanoparticles showed a more potent adjuvant activity than the larger nanoparticles. When dispersed in an aqueous medium, both aluminum hydroxide and aluminum phosphate are physically 1–20 micrometer particulates. There are data showing that particulate vaccine carriers of around 200 nm (or less) may be optimal in potentiating the immunogenicity of vaccines. Based on this finding, aluminum hydroxide nanoparticles of 112 nm were synthesized, and its adjuvant activity was compared to that of the traditional aluminum hydroxide adjuvant, which have particulates of 3-20 micrometer. Using ovalbumin and Bacillus anthracis protective antigen protein as model antigens, it was found that protein antigens adsorbed on the aluminum hydroxide nanoparticles induced stronger antigen-specific antibody responses than the same protein antigens adsorbed on the traditional aluminum hydroxide microparticles of around 9.3 µm. Importantly, the inflammation reactions induced by aluminum hydroxide nanoparticles in the injection sites were milder than that induced by microparticles. Simply reducing the particle size of the traditional aluminum hydroxide adjuvant in suspension from micrometers into nanometers represents a novel and effective approach to improve its potency. The second limitation was addressed by converting vaccines that contain an aluminum salt as an adjuvant from an aqueous dispersion into a dried powder using thin-film freeze-drying. There is evidence that aluminum-containing vaccines can be lyophilized to dry powders using high speed freezing methods. Thin-film freezing is a high speed freezing method with a freezing rate between 100 to 10,000 K/s, but the feasibility of using thin-film freeze-drying to freeze-dry vaccines that contain aluminum salts as adjuvants has not been tested before. In this dissertation, Using ovalbumin as a model protein antigen and aluminum hydroxide or aluminum phosphate as an adjuvant, it was confirmed that vaccines that are adjuvanted with aluminum hydroxide or aluminum phosphate can be freeze-dried with as low as 2% (w/v) of trehalose as a cryoprotectant by thin-film freeze-drying without causing vaccine aggregation while preserving the immunogenicity of the vaccine. Finally, the feasibility of using the thin-film freeze-drying method to freeze-drying vaccines that contain aluminum salts as adjuvants was further confirmed by drying a commercial aluminum salt-adjuvanted tetanus toxoid vaccine. Vaccines that contain aluminum salts as adjuvants may be converted to a dry powder using the thin-film freeze-drying method to avoid loss of potency due exposure to freezing conditions during transport and storage.text
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Каляева, М. И., and M. I. Kalyaeva. "Синтез и функциональные свойства композиционных сорбентов «катионит КУ-2x8-гидроксид олова (IV)» для избирательного извлечения тяжелых металлов : магистерская диссертация." Master's thesis, 2017. http://hdl.handle.net/10995/54443.
Full textAbstract:
В магистерской диссертации представлена методология пошагового синтеза композиционного сорбента на основе катионообменника и гидроксида титана (IV). Показаны результаты сорбции меди (II) и других тяжелых металлов синтезированным композиционным сорбентом. Для математического моделирования результатов сорбции были использованы изотермы Ленгмюра, Фрейндлиха и Темкина. Установлено, что модель Ленгмюра наиболее точно описывает сорбционный процесс. Определены константы модели Ленгмюра и площадь удельной поверхности композиционного сорбента. Гранулы композиционного сорбента изучены с помощью методов сканирующей электронной микроскопии (СЭМ) и энергодисперсионного микроанализа (ЭДМА). Вычислены коэффициенты распределения меди (II) в гранулах композиционного сорбента и степень сорбции меди (II) из водных растворов CuSO4 различной концентрации.The methodology of stepwise synthesis of the composite sorbent based on cation exchanger and tin(IV) hydroxide was demonstrated. The sorption results of copper(II) and other heavy metals onto the composite sorbent are presented. Langmuir, Freundlich and Temkin adsorption isotherms were used in mathematical modeling of the sorption data. The Langmuir model most accurately describes the sorption process. The constants of the Langmuir model and the specific surface area of the composite sorbent were defined. Granules of the composite sorbent were studied by scanning electron microscopy (SEM) and energy-dispersive X-ray microanalysis (EDXMA). The distribution coefficients of copper(II) in the composite sorbent and the sorption degree from CuSO4 aqueous solutions of various concentrations were computed.
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Wagner, Stefan. "Dünne Palladium-Wasserstoff-Schichten als Modellsystem: Thermodynamik struktureller Phasenübergänge unter elastischen und mikrostrukturellen Zwangsbedingungen." Doctoral thesis, 2014. http://hdl.handle.net/11858/00-1735-0000-0022-6048-1.
Full textAbstract:
In dieser Arbeit wurde am Modell der Hydridbildung in Wasserstoff-beladenen, 5 nm bis 2000 nm dünnen Palladium-Schichten der Einfluß der Schichtdicke sowie mikrostruktureller und elastischer Zwangsbedingungen auf die Thermodynamik von Phasenübergängen 1. Ordnung untersucht. Grundlage der Untersuchungen ist eine H-induzierte Volumendehnung des Palladiums, die infolge eines Konzentrationshubs ∆c_H bei der Hydridbildung sprunghaft erfolgt. Aus der Volumendehnung resultieren an der Schicht-Substrat-Grenzfläche und an inneren Grenzflächen wie Phasen- und Korngrenzen hohe mechanische Spannungsgradienten, die additiv zum chemischen Potential μ_H des Wasserstoffs beitragen und die Stabilität der Hydridphase verändern. Der Einfluß mechanischer Spannungen auf das chemische Potential wird durch die Mikrostruktur der Schichten modifiziert, die unterschiedliche H-Einlagerungsplätze im Palladium-Gitter mit einem Spektrum unterschiedlicher Platzenergien bereitstellt und die Kanäle eines möglichen Spannungsabbaus durch plastische Deformation der Schichten bestimmt.
Ziel dieser Arbeit war es, die sich überlagernden Einflüsse der Mikrostruktur und mechanischer Spannungen auf die Thermodynamik der Hydridbildung experimentell zu separieren und aus ihnen resultierende Abweichungen von der Thermodynamik des massiven Pd-H-Systems unter Bezugnahme auf thermodynamische Modellvorstellungen zu quantifizieren.
Durch gezielte Wahl der Herstellungsbedingungen präparierte Pd-Schichten texturiert nanokristalliner, multi-orientiert polykristalliner und epitaktischer Mikrostruktur wurden schrittweise mit Wasserstoff beladen. H-induzierte Änderungen des Spannungszustands, die Hydridbildung und plastische Änderungen der Schichten wurden in-situ insbesondere mit Methoden der Röntgendiffraktometrie, durch die Messung der Substratverbiegung, des elektrischen Widerstandes, der akustischen Emission der Schichten sowie mittels STM und Proton-Proton-Streuung untersucht.
Hinsichtlich mikrostruktureller Änderungen der Schichten bei H-Beladung wurden Kaskaden kritischer Schichtdicken und Spannungszustände des Einsetzens plastischer Deformation gefunden. Bereits im Bereich der elastischen Schichtdehnung wurden diskrete Relaxations-Ereignisse beobachtet, die auf die Bewegung intrinsischer Defekte zurückgeführt wurden. Für Schichtdicken unterhalb von 22-34 nm wurde ein neuer Typ eines partiell kohärenten Phasenübergangs belegt, bei dem die Phasengrenzflächen während des gesamten Phasenübergangs kohärent verbleiben.
Unter dem Einfluß der unterschiedlichen Mikrostrukturen und Spannungszustände der Schichten wurde eine signifikante Reduktion der elastischen H-H-Wechselwirkung – der Triebkraft der Hydridbildung – um 20-50 % gegenüber dem massiven System belegt. Für die Schichten beträgt E_HH 15-30 kJ/mol_H, während im massiven System E_HH = 36.8 kJ/mol_H. Der elastische Beitrag zur Reduktion der H-H-Wechselwirkung beträgt 2-5 kJ/mol_H. Er wächst für partiell kohärente Entmischung rasch an. Die entsprechenden Hydridbildungsenthalpien sind in Schichten um bis zu 3 kJ/mol_H erhöht. In lokal durch Faltenbildung relaxierten Schichten kann dies das räumliche Nebeneinander der α-Phase in haftenden Schichtbereichen und der Hydridphase in den Falten erzwingen.
Darüber hinaus wurde gezeigt, daß die Druck-Konzentrations-Isothermen dünner Pd-H-Schichten im Bereich des Phasenübergangs unter dem Einfluß nicht-linearer mechanischer Spannungen eine stetige Steigung aufweisen können. Dies macht eine Modifikation der Grenzbedingung zur Bestimmung der kritischen Temperatur der Hydridbildung erforderlich, bei der die Steigung ∂μ_H/∂c_H | T=T_c explizit ausgewertet wird. Die resultierenden kritischen Temperaturen der Pd-H-Schichten sind bis zu 40 % gegenüber dem massiven System reduziert. T_c ist 340-490 K für die Schichten, während T_c = 563 K für das massive System. In allen Schichten wurde bei 300 K noch immer ein Phasenübergang gefunden.
Insgesamt ließen sich die beobachteten Änderungen der Thermodynamik zumeist direkt an die Mikrostruktur und den Spannungszustand der Schichten koppeln, während allein an die Schichtdicke gebundene Finite-Size-Effekte bei den untersuchten Schichten von untergeordneter Bedeutung sind.