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This work was initially launched to study the synthesis of low-valent group 13 compounds bearing the bis(imino)pyridine ligand framework. Since its inception, this project has grown beyond the boundaries of group 13 to include low valent tin, silver, and rhenium. Alongside the reports of novel coordination compounds, we utilized computational chemistry to uncover unprecedented interactions which challenge conventional concepts of bonding. Synthesis, characterization, and complimentary computational studies are presented herein. Chapter 1 presents a historical overview of the bis(imino)pyridine ligand as well as our synthetic methodology and characterization of new ligand variants we have contributed to the literature. Chapter 2 presents the synthesis of a series of In(I) and In(III) bis(imino)pyridine complexes with varied sterics. Ligand-metal interaction and effect of ligand steric bulk on complex stability, as well as computational studies highlighting weak covalent interactions will be discussed. Chapter 3 presents the synthesis of Ga(III) bis(imino)pyridine complexes. Reactivity with “GaI” synthon as well as varied-stoichiometry one-pot synthesis attempts to generate low valent Ga-bis(imino)pyridine complexes will be discussed. Chapter 4 presents the synthesis of a series of Tl(I) bis(imino)pyridine complexes with varied sterics analogous to the approach taken with indium(I). Unprecedented weak ligand-metal as well as Tl-arene interactions will be discussed. Chapter 5 presents the synthesis of a series of Sn(II) bis(imino)pyridine complexes with varied sterics and halide substituents. Preferential cation-anion pair formation and attempted reactivity will be discussed. Chapter 6 presents the synthesis of a series of Ag(I) bis(imino)pyridine complexes with varied sterics. Resulting ligand-metal interactions as well as reactivity towards Lewis basic donor ligands will be discussed. Chapter 7 presents the synthesis of first crystallographically authenticated examples of rhenium(I) pincer complexes utilizing the bis(imino)pyridine ligand. Chapter 8 presents a general conclusion to the work.

Orientadora: Mônica Alonso Cotta / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Física Gleb Wataghin / Made available in DSpace on 2018-08-31T00:06:01Z (GMT). No. of bitstreams: 1 Silva_AldelianeMariada_M.pdf: 11574559 bytes, checksum: 5c39733d3a4441b98e7edbef8adbd795 (MD5) Previous issue date: 2016 / Resumo: Este trabalho apresenta resultados de nossa investigação sobre as propriedades elétricas do biossensor do tipo transistor de efeito de campo (FET, do inglês Field Effect Transistor) baseado em fosfeto de índio (InP). A estrutura deste biossensor consiste em um filme fino de InP do tipo-n crescido por Epitaxia de Feixe Químico (CBE, do inglês Chemical Beam Epitaxy) sobre um substrato de InP semi-isolante. No nosso biosensor, o contato da porta foi substituído por uma camada de biomoléculas carregadas de interesse para a detecção, funcionalizadas na camada de óxido do InP. O campo elétrico associado a estas biomoléculas pode modular o canal de condução. O sistema de interação específica utilizado foi a hibridização de fitas de ssDNA (single stranded DNA) complementares, onde os oligonucleotídeos receptores (probe) ssDNA foram imobilizados covalentemente na superfície da amostra. Este procedimento foi realizado através da oxidação com plasma de O2, seguida da funcionalização utilizando etanolamina e polietileno glicol (PEG), que serve como linker para a imobilização de receptores na superfície. As medidas elétricas de detecção foram feitas com as moléculas de target diluídas em buffer TRIS. A hibridização do DNA provoca um aumento na densidade de cargas na superfície, que consequentemente aumenta a largura da região de depleção no semicondutor, variando a resistência medida. A resposta do biossensor corresponde à variação da resistência em função da concentração de target. O biossensor apresentou sensibilidade para medidas de concentrações entre 10 pM e 30 pM, onde ocorre a saturação, e o tempo de resposta, no qual encontramos a estabilização do sinal medido, foi de aproximadamente 20 min. Variando a concentração de portadores e a espessura da camada semicondutora, verificamos alterações no limite de saturação (até ?M) e na sensibilidade do dispositivo. O controle destas propriedades, porém, mostrou-se limitado devido à variações na dopagem residual do semicondutor, e por isso discutimos aqui alternativas à geometria do dispositivo. Analisamos também a camada funcionalizada através de medidas de topografia e potencial de superfície usando métodos de microscopia de varredura por sonda (SPM, do inglês Scanning Probe Microscopy). Pudemos identificar a variação no potencial de superfície associada à imobilização do PEG e do DNA probe, mas não obtivemos resolução para o DNA target. Esta técnica permitiu porém verificar a estratificação de quatro níveis de potencial de superfície, no caso onde a funcionalização resultou em camadas mais espessas do que os valores típicos (~2 nm de espessura), em pequenas áreas do semicondutor / Abstract: This dissertation presents our results for the electrical properties investigation of Indium Phosphide (InP) based Field Effect Transistor (FET) biosensor. The structure of this biosensor consists of a thin n-type InP film grown by Chemical Beam Epitaxy (CBE) on a semi-insulating InP substrate. In our biosensor, the gate contact has been replaced by charged biomolecules of interest for detection, functionalized to the InP oxide layer. The electric field associated with these biomolecules provides the conduction channel modulation. The specific interaction system used here was the hybridization of single stranded-DNA (ssDNA) complementary oligonucleotides, for which the ssDNA receivers (probes) were covalently immobilized on the sample surface. The functionalization was carried out by oxidation with O2 plasma, followed by grafting biomolecules using ethanolamine and polyethylene glycol (PEG), which act as a linker for immobilizing the receptors on the surface. Electrical detection measurements were made with the target molecules diluted in TRIS buffer. DNA hybridization causes an increase in the surface charge density; consequently the semiconductor depletion width increases, affecting the measured resistance. The biosensor response function corresponds to the resistance variation as a function of target concentration. Our biosensor showed measured sensitivity to concentrations between 10 pM and 30 pM, for which signal saturation occurs. The response time, for which the measured signal stabilization was observed, was approximately 20 min. By varying the carrier concentration and the thickness of the semiconductor layer, we observed changes in the saturation limit (up ?M) and device sensitivity. The control of these properties, however, is limited due to variations in the residual doping of the semiconductor. Therefore we discuss here alternative device geometries. We also analyzed the functionalized layer by topography and surface potential measurements obtained using scanning probe microscopy (SPM) methods. We were able to identify the change in surface potential associated with the immobilization of PEG and probe DNA, but not for the target DNA. These techniques have however shown four surface potential levels in the case when the functionalization resulted in non-uniform layers, thicker than the typical values (~ 2 nm), in small areas of the semiconductor / Mestrado / Física / Mestra em Física / 165741/2014-7 / CNPQ

Master’s thesis focuses on the history and current progress in research of molten salt reactors around the world, with an emphasis placed on the properties of molten salts and the problems associated with their use. In relation to the practical part, one chapter is devoted to the creation of input file in the MCNP software. The practical part deals with neutron activation analysis of graphite prism experiment, which is filled with powder NaCl salt. This experiment is focused on the effect of salt on neutron flux with different energy levels. The whole problem was also simulated in the MCNP environment along with the experiment. At the end of the thesis, the individual methods are compared and evaluated.

The effects of various catalyst synthesis parameters on the photocatalytic degradation kinetics of aqueous methyl orange dye are presented. The four factors investigated were: i) InVO4 concentration, ii) nickel concentration, iii) InVO4 calcination temperature, and iv) ballmilling time. Three levels were used for each factor. Due to the large number of possible experiments in a full factorial experiment, an orthogonal-array experimental design was used. UV-vis spectrophotometry was used to measure the dye concentration. The results show that nickel concentration was a significant parameter, with 90% confidence. The relative ranking of importance of the parameters was nickel concentration > InVO4 concentration > InVO4 calcination temperature > milling time. The results of the orthogonal array testing were used to make samples of theoretically slowest and fastest catalysts. Curiously, the predicted-slowest catalyst was the fastest overall, though both samples were faster than the previous set. The only difference between the slowest and fastest catalysts was the milling time, with the longer-milled catalyst being more reactive. From this result, we hypothesize that there is an interaction effect between nickel concentration and milling time. The slowest and fastest catalysts were characterized using energy-dispersive spectroscopy (EDS), scanning electron microscopy (SEM), x-ray powder diffractometry (XRD), BET surface area analysis, and diffuse-reflectance spectroscopy (DRS). The characterization results show that the fastest catalyst had a lower band gap than the slowest one, as well as a slightly greater pore volume and average pore diameter. The results indicate that fast kinetics are achieved with low amounts of nickel and a long ball milling time. Under the levels tested, InVO4 concentration and the calcination temperature of the InVO4 precursor were not significant.

We present X-ray diffraction and Raman spectroscopy investigations of (InxGa1–x)2O3 thin films and bulk-like ceramics in dependence of their composition. The thin films grown by pulsed laser deposition have a continuous lateral composition spread allowing the determination of phonon mode properties and lattice parameters with high sensitivity to the composition from a single 2-in. wafer. In the regime of low indium concentration, the phonon energies depend linearly on the composition and show a good agreement between both sample types. We determined the slopes of these dependencies for eight different Raman modes. While the lattice parameters of the ceramics follow Vegard’s rule, deviations are observed for the thin films. Further, we found indications of the highpressure phase InGaO3 II in the thin films above a critical indium concentration, its value depending on the type of substrate.

abstract: Several key, open questions in astrophysics can be tackled by searching for and mining large datasets for transient phenomena. The evolution of massive stars and compact objects can be studied over cosmic time by identifying supernovae (SNe) and gamma-ray bursts (GRBs) in other galaxies and determining their redshifts. Modeling GRBs and their afterglows to probe the jets of GRBs can shed light on the emission mechanism, rate, and energetics of these events. In Chapter 1, I discuss the current state of astronomical transient study, including sources of interest, instrumentation, and data reduction techniques, with a focus on work in the infrared. In Chapter 2, I present original work published in the Proceedings of the Astronomical Society of the Pacific, testing InGaAs infrared detectors for astronomical use (Strausbaugh, Jackson, and Butler 2018); highlights of this work include observing the exoplanet transit of HD189773B, and detecting the nearby supernova SN2016adj with an InGaAs detector mounted on a small telescope at ASU. In Chapter 3, I discuss my work on GRB jets published in the Astrophysical Journal Letters, highlighting the interesting case of GRB 160625B (Strausbaugh et al. 2019), where I interpret a late-time bump in the GRB afterglow lightcurve as evidence for a bright-edged jet. In Chapter 4, I present a look back at previous years of RATIR (Re-ionization And Transient Infra-Red Camera) data, with an emphasis on the efficiency of following up GRBs detected by the Fermi Space Telescope, before some final remarks and brief discussion of future work in Chapter 5. / Dissertation/Thesis / Doctoral Dissertation Physics 2019

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With the advent of the 21st century, one of the serious problems facing mankind is harmful effects of global warming. Add to that the ever increasing cost of fuel and the importance of development of clean energy resources as alternative to fossil fuel has becomes one of the prime and pressing challenges for modern science and technology in the 21st century. Recent studies have shown that energy related sources account for 50% of the total emission of carbon dioxide in the atmosphere. All research activities are focused on developing various technologies that are capable of converting sunlight into electricity with high efficiency and can be produced using a cost-effective process. One of such technologies is the CuIn1-xGaxSe2 (CIGS) and its alloys that can be produced using cost-effective techniques and also exhibit high photo-conversion efficiency. The work presented here discusses some of the fundamental issues related to high volume production of CIGS thin film solar cells. Three principal issues that have been addressed in this work are effect of reduction in absorber thickness on device performance, micrononuniformity involved with amount of sodium and its effect on device performance and lastly the effect of working distance on the properties of molybdenum back contact. An effort has been made to understand the effect of absorber thickness on PV parameters and optimize the process parameters accordingly. Very thin (

<p>As the miniaturization of the transistors in integrated circuits approaches the atomic scale limit, novel materials with exceptional performance are desired. Moreover, to conduct enough current with an ultrathin and small-scale body, high drain current density is preferably required. Nevertheless, devices may suffer seriously from self-heating effect (SHE) with high drain bias and current if the generated heat cannot be dissipated efficiently. In this thesis, we introduce two material systems and several techniques to accomplish the demand without SHE. Tellurium, as a van der Waals material composed by atomic helical chains, is able to realize its one-dimensional structure. We illustrate that the cross-sectional current density of 150 MA/cm2 is achieved through boron nitride nanotube (BNNT) encapsulation without SHE due to the superior thermal conductivity of BN. With the nanotube encapsulation technique applied, one-dimensional tellurium nanowire transistors with diameter down to 2 nm are realized as well, and single tellurium atomic chain is isolated. Furthermore, atomic-layer-deposited indium oxide (In2O3) as thin-film transistors exhibit even better current carrying capacity. Through co-optimization of their electrical and thermal performance, drain current up to 4.3 mA/μm is achieved with a 1.9-nm-thick body without SHE. The alleviation of SHE is due to a) the high thermal conductivity of the substrate assisting on efficiently dissipating the generated thermal energy, b) SHE avoidance with short-pulse measurement, and c) interface engineering between the channel stack and the substrate. These two material systems may be the solid solution to the desire of high current density transistors in the post-Moore era.</p>