Melatonin is a neurohormone produced by the pineal gland in the brain. It functions as an antioxidant to scavenge free radicals. Free radicals are reactive species; they often oxidize the cells leading to oxidative stress which may lead to severe health complications. Reaction of melatonin with free radicals is known to be stepwise, as such the stability of the intermediates can be examined. Thus, the possibility of using melatonin as an in vivo spin trap can be determined. Spin traps allow characterization of unstable radical species using electron spin resonance spectroscopy. In this research, ab initio quantum chemistry techniques were used to calculate the energies of selected intermediates formed during the partial oxidation of melatonin by hydroxyl radical. Specifically, optimized geometries for melatonin, and selected intermediates with ·OH were obtained at the DFT/B3LYP/cc-pVXZ and HF/cc-pVXZ (X = D, T, Q) levels of theory. Extrapolations to the complete basis set limit were also performed.

We introduce an efficient thermodynamically consistent technique to extrapolate and interpolate normalized Canonical NVT ensemble averages like pressure and energy for Lennard-Jones (L-J) fluids. Preliminary results show promising applicability in oil and gas modeling, where accurate determination of thermodynamic properties in reservoirs is challenging. The thermodynamic interpolation and thermodynamic extrapolation schemes predict ensemble averages at different thermodynamic conditions from expensively simulated data points. The methods reweight and reconstruct previously generated database values of Markov chains at neighboring temperature and density conditions. To investigate the efficiency of these methods, two databases corresponding to different combinations of normalized density and temperature are generated. One contains 175 Markov chains with 10,000,000 MC cycles each and the other contains 3000 Markov chains with 61,000,000 MC cycles each. For such massive database creation, two algorithms to parallelize the computations have been investigated. The accuracy of the thermodynamic extrapolation scheme is investigated with respect to classical interpolation and extrapolation. Finally, thermodynamic interpolation benefiting from four neighboring Markov chains points is implemented and compared with previous schemes. The thermodynamic interpolation scheme using knowledge from the four neighboring points proves to be more accurate than the thermodynamic extrapolation from the closest point only, while both thermodynamic extrapolation and thermodynamic interpolation are more accurate than the classical interpolation and extrapolation. The investigated extrapolation scheme has great potential in oil and gas reservoir modeling.That is, such a scheme has the potential to speed up the MCMC thermodynamic computation to be comparable with conventional Equation of State approaches in efficiency. In particular, this makes it applicable to large-scale optimization of L-J model parameters for hydrocarbons and other important reservoir species. The efficiency of the thermodynamic dependent techniques is expected to make the Markov chains simulation an attractive alternative in compositional multiphase flow simulation.

Desde el surgimiento de la corriente New Wave, las narraciones del género de la ciencia ficción contenían un significado simbólico como una alegoría a nuestra condición como humanos. Las avanzadas construcciones tecnológicas, los seres no humanos y los mundos distópicos empezaron a cumplir un rol más profundo de lo que tradicionalmente fueron al ser meramente elementos visuales llamativos a ojos del espectador. Tanto en las obras literarias como en las películas del género, se desarrollan como subtextos una serie de denuncias al control de poderes, lucha de clases, violencia de género, xenofobia, por mencionar algunos. Conflictos humanos que han existido desde hace bastante tiempo y afecta en cómo nos relacionamos con nuestros semejantes. La presente investigación tiene como objetivo analizar esos cuestionamientos que hace la ciencia ficción en relación a lo humano, presentes en la serie de televisión de HBO Westworld, a través de los recursos del lenguaje audiovisual como el desarrollo de sus personajes, los conflictos de sus subtramas y sus espacios físicos. / Since the emergence of the New Wave phase, the narratives of the sci-fi genre contained symbolic significance as an allegory to our status as humans. Advanced technological constructions, non-humans and dystopian worlds began to play a deeper role than they traditionally were by being merely striking visual elements in the eyes of the viewer. In both literary works and films of the genre, a series of complaints of power control, class struggle, gender violence, xenophobia, to name a few are developed as subtexts. Human conflicts that have been around for quite some time and affect how we relate to our fellowmen. This research aims to analyze those questions that science fiction makes in relation to the human, presents in the HBO television series Westworld, through the resources of audiovisual language such as the development of its characters, conflicts of their subplots and physical spaces. / Trabajo de investigación

Modelování turbínových charakteristik je nutným předpokladem pro detailní simulaci výměny náplně válce turbodmychadlem přeplňovaných spalovacích motorů. Kromě toho je možnost stanovení účinnosti a průtokové kapacity v libovolných pracovních bodech klíčová pro porovnání různých turbínových stupňů. Cílem této práce je předložit jednotnou metodu pro oba účely tak, aby bylo možné provést porovnání použitím přesně stejných modelů turbín jako při následné simulaci pracovního oběhu motoru. Zdrojem vstupních dat je obvykle měření na plynové zkušebně, které však umožňuje zachycení pouze omezeného pracovního rozsahu turbíny. V této práci jsou navrženy metody umožňující zvýšení věrohodnosti a robustnosti extrapolace turbínových charakteristik, přičemž optimalizace je využita k určení takových parametrů hledaných funkcí, které vedou k nejlepší shodě mezi modelem a vstupními daty.

No description available.

Analytic functions in a domain Ω are uniquely determined by their values on any curve Γ ⊂ Ω. We provide sharp quantitative version of this statement. Namely, let f be of order E on Γ relative to its global size in Ω (measured in some Hilbert space norm). How large can f be at a point z away from the curve? We give a sharp upper bound on |f(z)| in terms of a solution of a linear integral equation of Fredholm type and demonstrate that the bound behaves like a power law: E^γ(z). In special geometries, such as the upper halfplane, annulus or ellipse the integral equation can be solved explicitly, giving exact formulas for the optimal exponent γ(z). Our methods can be applied to non-Hilbertian settings as well. Further, we apply the developed theory to study the degree of reliability of extrapolation of the complex electromagentic permittivity function based on its analyticity properties. Given two analytic functions, representing extrapolants of the same experimental data, we quantify how much they can differ at an extrapolation point outside of the experimentally accessible frequency band.

No description available.

Melatonin (N-acetyl-5-methoxytryptamin, MLT) is a naturally occurring antioxidant which has shown some potential for use as a spin trap. Spin traps react with short lived hydroxyl radicals (HO·) to produce more stable products called spin adducts which may be characterized by electron paramagnetic resonance spectroscopy. However, the relative stability of hydroxyl spin adducts of melatonin derivatives (MLTD) compared to 2-hydroxymelatonin (HO-MLT) has not been examined computationally. Computational studies have been done on four selected MLTD; methylmelatonin (Me-MLT), chloromelatonin (Cl-MLT), cyanomelatonin (CN-MLT), and nitromelatonin (NO2-MLT). Geometry of the structures were optimized at the HF/6-31G(d), cc-pVXZ, (X=D and T) and DFT/B3LYP/6-31G(d), cc-pVDZ and cc-pVTZ levels of theory and extrapolated to the complete basis set limit using cc-pVXZ (X=D, T) basis sets. The lowest relative energy was found to be a mix of results for 2-OH-MLT-Me at HF and 2-OH-MLT-NO2 at DFT.

No description available.

Molecular nonlinear optical (NLO) properties are extensively studied using both theory and experiment because of their use in myriad applications. Experimental measurements of the most interesting molecules’ NLO properties are difficult, so experimental data for molecules with desirable NLO properties is scarce. Theoretical tools don’t suffer from the same limitations and can provide significant insights into the physico-chemical phenomena underlying the nonlinear responses, can help in interpreting response behaviour of molecules, and can guide design the materials with desirable response properties. Here, I present my work on developing methods for accurately calculating the NLO properties of molecules using the finite field (FF) approach. The first chapter provides a background for the finite field and electronic structure methods used in this dissertation. Chapter two is a thorough investigation of the finite field method. The limitations of the method are highlighted and the optimal conditions for overcoming its drawbacks and obtaining meaningful and accurate results are described. Chapter three presents the first systematic study of the dependence of optimal field strengths on molecular descriptors. The first protocol for predicting the optimal field for the second hyperpolarizability is presented and successfully tested, and the dependence of the optimal field strength for the first hyperpolarizability on the molecular structure is investigated. Chapter four is an assessment of various DFT functionals in calculating the second hyperpolarizabilities of organic molecules and oligomers. This study shows the limitations of conventional DFT methods and the importance of electron correlation to response properties. In chapter five we present a new method of calculating NLO properties using a rational function model that is shown to be more robust and have lower computational cost than the traditional Taylor expansion. Finally, chapter six includes a summary of the thesis and an overview of future work. / Thesis / Doctor of Philosophy (PhD)