Dissertations / Theses on the topic 'Electronic effects'
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Cao, Hui. "Dynamic Effects on Electron Transport in Molecular Electronic Devices." Doctoral thesis, KTH, Teoretisk kemi, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-12676.
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HTML clipboardIn this thesis, dynamic effects on electron transport in molecular electronic devices are presented. Special attention is paid to the dynamics of atomic motions of bridged molecules, thermal motions of surrounding solvents, and many-body electron correlations in molecular junctions. In the framework of single-body Green’s function, the effect of nuclear motions on electron transport in molecular junctions is introduced on the basis of Born-Oppenheimer approximation. Contributions to electron transport from electron-vibration coupling are investigated from the second derivative of current-voltage characteristics, in which each peak is corresponding to a normal mode of the vibration. The inelastic-tunneling spectrum is thus a useful tool in probing the molecular conformations in molecular junctions. By taking account of the many-body interaction between electrons in the scattering region, both time-independent and time-dependent many-body Green’s function formula based on timedependent density functional theory have been developed, in which the concept of state of the system is used to provide insight into the correlation effect on electron transport in molecular devices. An effective approach that combines molecular dynamics simulations and first principles calculations has also been developed to study the statistical behavior of electron transport in electro-chemically gated molecular junctions. The effect of thermal motions of polar water molecules on electron transport at different temperatures has been found to be closely related to the temperature-dependent dynamical hydrogen bond network.QC20100630
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Foley, Simon Timothy. "Effects of electron-electron interactions on electronic transport in disordered systems." Thesis, University of Birmingham, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.273932.
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Margaritis, Georgios. "Thermomechanical effects in electronic packages." Thesis, Massachusetts Institute of Technology, 1994. http://hdl.handle.net/1721.1/12250.
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Ngo, Anh T. "Spin-orbit Effects and Electronic Transport in Nanostructures." Ohio University / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1292260134.
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Macovez, Roberto. "Surface electronic structure of fullerides effects of correlation, electron-phonon coupling, and polymerization /." [S.l. : Groningen : s.n. ; University Library of Groningen] [Host], 2007. http://irs.ub.rug.nl/ppn/305433423.
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Rickard, Malcolm J. "Electronic electrooptic effects in ferroelectric liquid crystals." Diss., Connect to online resource, 2005. http://wwwlib.umi.com/cr/colorado/fullcit?p3190375.
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Barnett, Christopher Bevan. "Electronic and solvent effects on monosaccharide conformations." Master's thesis, University of Cape Town, 2007. http://hdl.handle.net/11427/7487.
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The hydroxymethyl group rotational preferences of the monosaccharides glucose and galactose are different from each other and non-intuitive (from a steric point of view) in their preferences for gauche conformers. These molecules exhibit very different biological and thermodynamic properties in, for example their binding to glycosides or their liquid crystalline phases in glycolipids. The preference for gauche conformations has been attributed to solvent effects, stereo-electronic effects and hydrogen bonding; yet the experimentally obtained hydroxymethyl rotational populations have not yet been fully rationalised. In this dissertation, I have used a range of ab initio, Molecular Dynamics (MD), Quantum Mechanics/Molecular Mechanics (QM/MM) and free energy computational methods to resolve and explain this observation. The hydroxymethyl free energy surface was calculated using the Potential of Mean Force (PMF), umbrella sampling and Weighted Histogram Analysis Methods (WHAM). The PMF calculations were performed in the canonical (NVT) ensemble in the gaseous and aqueous phase where each monosaccharide was modelled with Parameter Model 3 for Carbohydrates (PM3CARB-I). Density Functional Theory (OFT) calculations were also carried out and Atoms in Molecules (AIM) and Natural Bond Orbital (NBO) analyses were applied. Gaseous phase simulation results for both glucose and galactose gave hydroxymethyl rotational preferences of gg>tg>gt and gt>gg>tg respectively. These conformational preferences can be rationalised in terms of an intrinsic stereo-electronic effect (found from NBO calculations) and strong intramolecular hydrogen bonding (found in the tg conformer of glucose and the gg conformer of galactose using AIM) in the gaseous phase. The addition of solvent (water) was found to disrupt the intramolecular hydrogen bonding present in the gaseous phase. Hydroxymethyl rotational preferences in the solution phase were gg>gt>tg for glucose and gt>tg>gg for galactose. The population distributions in solution were also calculated for glucose as gg:gt:tg = 59.21 :34.88:0.83 and for galactose as gg:gt:tg = 3.32:79.60: 1 0.15. These populations agree favourably with experimental NMR populations. The solvent conformational preference is dominated by the intrinsic stereoeIectronic effect and steric interactions. The gauche effect in monosaccharides has been successfully rationalised.
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Tian, Guangjun. "Electron-vibration coupling and its effects on optical and electronic properties of single molecules." Doctoral thesis, KTH, Teoretisk kemi och biologi, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-122180.
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The thesis is devoted to theoretical investigations of electron-vibration coupling and its effects on optical and electronic properties of single molecules, especially for molecules confined between metallic electrodes. A density-matrix approach has been developed to describe the photon emission of single molecules confined in the scanning tunneling microscope (STM). With this new method electronic excitations induced by both the tunneling electron and the localized surface plasmon (LSP) can be treated on an equal footing. Model calculations for porphyrin derivatives have successfully reproduced and explained the experimentally observed unusual variation of the photon emission spectra. The method has also been extended to study the STM induced fluorescence and phosphorescence of C60 molecules in combination with the first principles calculations. In particularly, the non-Condon vibronic couplings have been exclusively included in the calculations. The experimental spectra have been nicely reproduced by our calculations, which also enable us to identify the unique spectral fingerprint and origin of the measured spectra. The observed rich spectral features have been finally correctly assigned. The electron transport properties of molecular junctions with bipyridine isomers have been studied in the sequential tunneling (SET) regime by assuming that the molecules are weakly coupled to metallic electrodes. It is shown that the strong electron-vibration coupling in the 2, 2’-bipyridine molecule and the 4,4’-bipyridine molecule can lead to observable Franck-Condon blockade. Taking advantage of such novel effect, a gate-controlled conductance switch with ideal on-off ratio has been proposed for a molecular junction with the 4, 4’-bipyridine molecule. The effect of the electron-vibration coupling on one-photon and two-photon absorption spectra of green fluorescent protein (GFP) has been systematically examined. The hydroxybenzylidene-2, 3-dimethylimidazolinone molecule in the deprotonated anion state (HBDI−) is used to model the fluorescence chromophore of the GFP. Both Condon and non-Condon vibronic couplings have been considered in the calculations. The calculated spectra are in good agreement with the available experimental spectra. It confirms the notion that the observed blue-shift of the two-photon absorption spectrum with respect to its one-photon absorption counterpart is caused by the non-Condon vibronic coupling. All the calculations are carried out with our own software package, DynaVib. It is capable of modeling a variety of vibrational-resolved spectroscopies, such as absorption, emission, and resonant Raman scattering (RRS) spectra. In our package, the Duschinsky rotation and non-Condon effect have been fully taken into account. Both time-independent and time-dependent approaches have been implemented, allowing to simulate the spectra of very large molecules.QC 20130520
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Germain, François. "A nonlinear analysis framework for electronic synthesizer effects." Thesis, McGill University, 2011. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=104845.
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This thesis presents a theoretical and experimental study of the nonlinear behaviour of analog synthesizers' effects. The goal of this thesis is to evaluate and complete current research on nonlinear system modelling, both in and out of the field of music technology. The cases of single-input and multiple-input effects are considered.We first present an electronic analysis of the circuits of common examples of analog effects such as Moog's lowpass filter and Bode's ring modulator, extracting the equations of each system. We then discuss the results of experiments made on these systems in order to extract qualitative information about the distortion found in the system input-output relationship.Secondly, we look at the literature for methods used to model single-input nonlinear systems, and we investigate the opportunities to extend these techniques to multi-input systems. We focus on two different modelling approaches. The black-box approach seeks to model the input-output transfer function of the system as closely as possible without any particular assumption on the system. The circuit modelling approach uses the knowledge of electronic component behaviour to extract a transfer function from the known circuit of the system. The results of both approaches are compared to our experiments in order to evaluate their accuracy, identify flaws and, when possible, suggest potential improvements of the methods.Cette thèse présente une étude théorique et expérimentale du comportement nonlinéaire des effets de synthétiseurs analogiques. Elle vise à évaluer et compléter les recherches actuelles sur la modélisation des systèmes non-linéaires, à la fois dans le domaine de la technologie de la musique et en dehors. Les cas des effets à une ou plusieurs entrées sont examinés. Pour ce faire, nous présentons d'abord une analyse électronique des circuits de plusieurs exemples usuels d'effets analogiques tels que le filtre passe-bas de Moog ou le modulateur en anneau de Bode. Les équations régissant chaque système en sont dérivées. Nous discutons ensuite le résultat d'expériences menées sur ces systèmes pour extraire une caractérisation qualitative de la distorsion présente dans le rapport entrée-sortie du système. Dans un second temps, nous examinons les méthodes de modélisation des systèmes non-linéaires à une entrée trouvées dans la littérature, et nous explorons les possibilités d'extension de ces techniques aux systèmes à plusieurs entrées. Deux approches de modélisation sont abordées. L'approche boîte noire vise à modéliser la fonction de transfert entrée-sortie du système aussi fidèlement que possible sans hypothèse sur la structure du système. L'approche de la modélisation du circuit utilise quant à elle la connaissance du comportement des composants électroniques pour extraire une fonction de transfert à partir du circuit (connu) du système. Les résultats associés aux deux approches sont comparés à nos expériences pour évaluer leur performance, et identifier des lacunes et, quand c'est possible, des opportunités d'amélioration de ces méthodes.
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Neumann, Ingmar. "Electronic spin transport and thermoelectric effects in graphene." Doctoral thesis, Universitat Autònoma de Barcelona, 2014. http://hdl.handle.net/10803/145396.
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La espintrónica y la espín caloritronica en grafeno son campos de investigación muy activos, y esta tesis es una contribución a ambos campos. El tema principal es el estudio de la corriente de espín a través de métodos de inyección y detección eléctrica en válvulas de espín no locales de grafeno. Preliminarmente, estudiamos analíticamente el efecto túnel de electrones de conducción entre materiales ferromagnéticos y no magnéticos. En la parte experimental, se investiga la precesión de espín en las válvulas de espín de grafeno en suspensión. En este contexto, hemos desarrollado un nuevo método para la fabricación de dispositivos de grafeno suspendido que, además, proporciona una inyección y detección de espín más eficiente. Con el fin de investigar estas corrientes de espín más eficientes, hemos realizado medidas en función de la corriente inyectada. Estos experimentos han dado lugar a la demonstración experimental de un termopar de espín en grafeno.
La predicción teórica de distancias de relajación de espín de varias decenas de micrómetros en grafeno nos ha motivado a estudiar las propiedades intrínsecas de grafeno. Para ello el grafeno es suspendido libremente, eliminando así las influencia de substrato y permitiendo a posteriori emplear métodos de limpieza. Con el fin de lograr este objetivo, hemos desarrollado un método de fabricación de válvulas de espín no locales de grafeno suspendido libremente, que implica la utilización en el proceso de un número mínimo de pasos y productos químicos. Dado que en este método no se emplean ácidos, el rendimiento de estos dispositivos de alta calidad se mejora notablemente comparado con dispositivos elaborados con un proceso de fabricación estándar. Por lo tanto, nuestros dispositivos presentan una excelente movilidad, alcanzando valores de 20.000cm^2/(Vs) a temperatura ambiente. La detección eléctrica de la precesión de espín nos permite extraer la longitud de relajación en estos dispositivos, encontrando valores de pocos micrómetros.
Hemos observado además una alta eficiencia tanto de inyección como en la detección de espín en nuestros dispositivos. Esta mejora es atribuida a la formación de una barrera de carbono amorfo inducida por haz de electrones en la interfaz grafeno/electrodo ferromagnético. Estas interfaces son estables incluso a altas densidades de corriente. Obtenemos una mejora 10000x de la señal de espín con respecto a los contactos óhmicos. La resistencia de contacto y acumulación de espín aumentada sugiere que la interfaz es una combinación de contacto óhmico y barrera túnel. La simplicidad y capacidad de transferencia del proceso de fabricación contrasta con la complejidad de obtener barreras aislantes convencionales utilizadas hoy en día en dispositivos espintrónicos. Por tanto, esperamos que las barreras de carbono amorfo sean una alternativa viable para mejorar tanto la eficiencia en la inyección como en la detección de corrientes de espín en otros materiales distintos a grafeno.
Por último, hemos realizado medidas en estos dispositivos en función de la corriente inyectada, observando un fenómeno nuevo gracias a las propiedades particulares de grafeno como su movilidad dependiente de la energía. Se demuestra que un aumento anómalo de la acumulación de espín en el punto Dirac, que es causado por calentamiento en los inyectores. Debido a este contribución de grados mayores para la acumulación de espín , los potenciales electroquímicos de los sub bandas de espín presentan un comportamiento supra lineal en función de la corriente de bias. El desdoblamiento de espín se hace tan grande que en el punto Dirac se observa una gran cantidad de portadores de espín y carga opuestos. Demuestramos que este constituye un termopar de espín, donde el voltaje termoeléctrico entre el espín hacia arriba y hacia abajo aumenta la acumulación total de espínSpintronics and spin caloritronics in graphene are recently very active fields of research, and this thesis is a contribution to both. The main topic is the study of spin currents in graphene non local spin valves via means of electrical spin injection and detection. In a preliminary work, we analytically investigate the tunneling process of conduction electrons between ferro- and non magnetic materials. On the experimental side, we report on spin precession in freely suspended graphene spin valves. In this context, we have developed a novel method for the fabrication of freely suspended graphene devices, which additionally is beneficial for the spin injection/detection efficiency of the devices. In order to investigate these enhanced spin signals, we have performed bias dependent measurements, which lead to the experimental demonstration of a spin thermocouple in graphene. In order to investigate tunneling of conduction electrons between ferro- and non magnetic electrodes, we have developed a theoretical model based on the analytical solution of the one-dimensional, time-independent Schrˆdinger equation. The model shows that a complex behavior of the polarization is intrinsic to the tunneling process of electrons between ferro- and non magnetic materials. Spin relaxations times of several tens of micrometers in graphene have been predicted. A promising approach to studying the intrinsic properties of graphene is to suspend the flakes, thus eliminating the influence of the substrate and enabling cleaning methods. In order to achieve this, we have developed a method to fabricate freely suspended graphene non local spin valves that involves a minimal number of steps and chemicals. Since the method is acid free, the yield of high quality, as-processed devices is notably improved when comparing to the standard fabrication process. Therefore, our as-processed devices exhibit excellent mobility, as high as 20000 cm^2/(Vs) at room temperature. We demonstrate electrical detection of spin precession, allowing us to extract the spin relaxation length in these devices, finding values of a few micrometers. We expect that by applying cleaning methods to freely suspended spin valves, it will be possible to investigate the origins of spin relaxation in intrinsic graphene. We have further observed enhanced spin injection/detection efficiency in our devices. We attribute the enhancement to the formation of an amorphous carbon layer at the interface between graphene and ferromagnet due to electron beam induced deposition. The interfaces are stable even for large applied bias current densities. We obtain a 10000x enhancement of the spin signal as compared to Ohmic contacts, but expect further increase after optimizing the deposition method. The increased contact resistance and spin accumulation suggests that the interface has a combination of Ohmic and tunneling properties. The simplicity and transferability of the fabrication process is in contrast to those of the conventional insulators used in spintronics. Therefore, we expect that amorphous carbon barriers are a viable alternative, which might improve the spin injection/detection efficiency in other materials as well. Finally, we have performed bias dependent measurements in our samples, observing a novel phenomenon which is due to the particular properties of graphene such as its energy dependent mobility. We demonstrate an anomalous enhancement of the spin accumulation at the Dirac point, which is caused by heating in the injector contacts. Because of this higher order contribution to the spin accumulation, the electrochemical potentials of the spin sub bands exhibit supralinear behavior as a function of the bias current. The spin splitting becomes so large that at the Dirac point we observe a huge quantity of carriers of opposite spin and charge. We show that this constitutes a spin thermocouple, where the thermoelectric voltage between spin up and spin down enhances the total spin accumulation.
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Aparicio, Sánchez Pablo Arturo. "Electronic Effects Governing the Redox Properties of Polyoxometalates." Doctoral thesis, Universitat Rovira i Virgili, 2014. http://hdl.handle.net/10803/352216.
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Els polioxometalats (POMS) són agregats inorgànics compostos per oxigen i metalls de transició, normalment en el seu estat d'oxidació més alt. Aquest fet fa que una de les seves principals característiques sigui el seu gran caràcter oxidant. A més al contenir un alt nombre de metalls, aquests poden ser reduïts fàcilment, donant lloc a noves propietats no observades en els mateixos compostos sense reduir. Els nostres estudis s'han basat principalment en càlculs mecano-quàntics (teoria del funcional de la densitat, DFT en anglès). Molts estudis experimentals s'han realitzat durant les últimes dècades abastant el tema de les mono-reduccions, on aquests compostos guanyen un electró. En aquesta tesi s'ha volgut partir d'aquests resultats i hem ampliat l'estudi a les reduccions amb dos i tres electrons en diversos sistemes de composició i grandària diferent. Ens hem centrat bàsicament en l'estudi dels compostos anomenats Keggin (12 metalls) i Wells-Dawson (18 metalls). A més, compostos derivats d'aquests també han estat estudiats, en concret els mono-substituïts, on un dels metalls és substituït per un altre diferent.Los polioxometalatos (POMs) son agregados inorgánicos compuestos por oxígeno y metales de transición, normalmente en su estado de oxidación más alto. Este hecho hace que una de sus principales características sea su gran carácter oxidante. Además al contener un alto número de metales, estos pueden ser reducidos fácilmente, dando lugar a nuevas propiedades no observadas en los mismos compuestos sin reducir. Nuestros estudios se han basado principalmente en cálculos mecano-cuánticos (teoría del funcional de la densidad, DFT en inglés). Muchos estudios experimentales se han realizado durante las últimas décadas abarcando el tema de las mono-reducciones, donde estos compuestos ganan un electrón. En esta tesis se ha querido partir de esos resultados y hemos ampliado el estudio a las reducciones con dos y tres electrones en varios sistemas de composición y tamaño distinto. Nos hemos centrado básicamente en el estudio de los compuestos denominados Keggin (12 metales) y Wells-Dawson (18 metales). Además, compuestos derivados de éstos también han sido estudiados, en concreto los mono-sustituidos, donde uno de los metales es sustituido por otro diferente. Nuestros mayores logros han sido reproducir las tendencias experimentales y explicar efectos que hasta el momento no se habían podido resolver.
The polyoxometallates (POMs) aggregates are inorganic compounds of transition metals and oxygen, usually in its highest oxidation state. This fact makes one of its main characteristics is its high oxidizing character. In addition to they contain a large number of metals, that can be easily reduced, resulting in new properties not observed in the same compounds without reducing. Our studies have been based mainly on quantum mechanical calculations (theory of density functional, DFT). Many experimental studies have been conducted over the past decades covering the issue of mono-reductions where these compounds gain an electron. In this thesis we have started from these results and we have extended the study to the reductions with two and three electrons in various systems of different size and composition. We focused mainly on the study of compounds called Keggin (12 metals) and Wells-Dawson (18 metals) polyoxoanions. Furthermore, derivatives of these compounds have also been studied, in particular the mono-substituted, wherein one of the metals is replaced by a different one.
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Rutherford, A. "Electronic effects in radiation damage simulations in metals." Thesis, University College London (University of London), 2009. http://discovery.ucl.ac.uk/15817/.
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Radiation damage has traditionally been modelled using classical molecular dynamics, in which the role of the electrons is confined to describing bonding via the interatomic potential. This is generally sufficient for low radiation energies. However high energy atoms lose a significant proportion of their energy to electronic excitations, therefore a simulation of the relaxation of a metallic lattice after a high energy event requires a description of the energetic interaction between atoms and electrons. The mechanisms of inelastic collisions between electrons and ions, coupling between electrons and phonons and the diffusion of energy through the electronic system to the rest of the lattice become signficant. We have coupled large scale MD simulations of the lattice to a continuum model for the electronic temperature evolution. Energy lost by the atoms due to elastic and inelastic electronic collisions is gained by the electronic system and evolves according to a heat diffusion equation. The electronic energy is coupled to the lattice via a modified Langevin thermostat, representing electron-phonon coupling. Results of the simulation of both displacement cascades and ion tracks, representing the low and high extremes of incident ion energy respectively, are presented. The effect of annealing of pre-existing damage by electronic excitation is studied and the behaviour under swift heavy ion irradiation in iron and tungsten is compared. In simulations of displacement cascades, the strength of coupling between the atoms and electrons emerges as the main parameter determining residual damage. Our new methodology gives rise to reduced damage compared to traditional methods in all cases. Ion track simulations demonstrated that the relaxation dynamics, and hence the residual damage, was dependent on the magnitude and temperature dependence of the electronic thermal parameters.
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Crain, Jason. "Pressure-induced structural and electronic effects in solids." Thesis, University of Edinburgh, 1993. http://hdl.handle.net/1842/10869.
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A series of detailed experimental and computational studies on aspects of pressure-induced phase transitions in solids is described. The emphasis is on the nature of such transitions in tetrahedral semiconductors. It is found that the materials investigated exhibit previously unreported and very complex behaviour which is related to the structural transition. New high-pressure diffraction evidence suggests that the crystallographic structures of several III-V semiconductors are not in agreement with those suggested either by prior experimentation or total energy calculation. The high-pressure structures determined in this work are generally of lower symmetry than previously believed and in at least one case of much greater complexity. It is also argued that phase-transition-induced defects are created at the transition in many of these materials and that the transition may be sensitive to either the concentration or mobility of such defects. The development and implementation of a simple new x-ray detection method has allowed for the observation of these subtle processes for the first time. To a certain degree, these novel aspects of previously well-studied transitions are now amenable to theoretical and computational treatment through the advances made in modern computer technology and parallel algorithms. As a result, new ab-initio local density functional investigations of structural stability and possible transition routes in one of these materials have been performed and the results are in good agreement with observation. Also the issue of defects has been treated by Car-Parrinello-type pseudopotential calculations on defect energies. It is found, among other things that the defect formation energies are relatively low and that structural relaxation under the influence of Hellmann-Feynman forces is necessary in order to obtain accurate values of such energies. The remainder of the thesis is devoted to an exploration of pressure-induced metastable forms of group IV and III-V semiconductors. These studies unite and compare results from image plate experiments, ab-initio pseudopotential calculations as well as empirical calculations using pair potentials and are applied in an attempt to make speculations as to the relative structural stability of these phases at finite temperature.
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Pereira, Vítor Manuel. "Disorder and localization effects in correlated electronic systems." Tese, Porto : edição do autor, 2006. http://catalogo.up.pt/F?func=find-b&local_base=FCB01&find_code=SYS&request=000088367.
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Bidaki, Laila June. "The effects of electronic performance monitoring on performance." CSUSB ScholarWorks, 2004. https://scholarworks.lib.csusb.edu/etd-project/2588.
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Hodges, Matthew P. P. "Magnetic field-induced electronic effects in organic semiconductors." Thesis, University of Sheffield, 2013. http://etheses.whiterose.ac.uk/5149/.
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Lechasseur, Ariane. "Pulmonary and systemic effects of electronic cigarette use." Doctoral thesis, Université Laval, 2021. http://hdl.handle.net/20.500.11794/70279.
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Le marché de la cigarette électronique est en constante expansion. La majorité des utilisateurs de cigarette électronique sont également des fumeurs de cigarette de tabac. Un nombre croissant de jeunes commencent à utiliser la cigarette électronique, sans avoir fumé la cigarette de tabac au préalable. Outre le propylène glycol et le glycérol, le liquide de la cigarette électronique peut contenir différentes concentrations de nicotine et se décliner dans près de 15 000 mélanges de saveurs. Le glycérol est un substrat métabolique impliqué dans la production de glucose en période de jeûne, et de lipides en période d'excès de glucides. Les impacts de la cigarette électronique sur la santé restent à déterminer. L'hypothèse générale de cette thèse est que l'utilisation de la cigarette électronique perturbe la biologie pulmonaire et métabolique. Le premier objectif de cette thèse était d'évaluer les effets de la variation des paramètres physiques de la cigarette électronique ainsi que la composition du liquide de vapotage sur la taille des particules d'aérosols générée. L'extension e-cigarette InExpose (SCIREQ) a été utilisée. Différentes concentrations de nicotine, saveurs et proportions de propylène glycol et glycérol ont été utilisées. La taille des particules des vapeurs de cigarette électronique a été analysée par un Scanning Mobility Particle Sizer spectrometer (SMPS 3080, TSI Inc). Nous avons montré qu'une puissance de la cigarette électronique plus élevée augmente la taille des particules émises. Nous avons également montré qu'une plus grande proportion de glycérol, la présence de nicotine et de vanilline augmente la taille des particules. Ces changements modifient la déposition pulmonaire prédite des particules de cigarette électronique. Le deuxième objectif de cette thèse était d'investiguer les effets pulmonaires de la double exposition aux vapeurs de cigarette électronique et à la fumée de cigarette. L'exposition de souris BALB/c femelles à la fumée de cigarette 3R4F a été effectuée dans un système automatisé de type « whole-body » (SIU24, Promech Lab AB). L'exposition aux vapeurs de cigarette électronique a été réalisée dans un système « whole-body » développé dans notre laboratoire, et en utilisant un liquide de vapotage sans saveurs et sans nicotine. Pour les deux types d'expositions, les souris ont été exposées successivement 2h/jour, 5 jours/semaine pendant 8 semaines. Nous avons montré que les souris exposées aux vapeurs de cigarette électronique et à la fumée de cigarette présentent des changements dans l'expression de gènes impliqués dans la régulation du cycle circadien. Nous avons montré une augmentation de la fréquence des cellules dendritiques, macrophages, neutrophiles, lymphocytes B ainsi que lymphocytes T CD4+ et CD8+ au poumon comparativement aux souris exposées seulement à la fumée de cigarette. L'exposition aux vapeurs de cigarette électronique a également modulé les niveaux d'immunoglobulines dans le lavage bronchoalvéolaire et le sérum. Une augmentation de la résistance des voies aériennes a été observée pour les souris exposées aux vapeurs de cigarette électronique, avec ou sans exposition concomitante à la fumée de cigarette. Le troisième objectif de cette thèse était de caractériser les effets de l'inhalation de vapeurs de glycérol sur le métabolisme énergétique hépatique. Les souris ont été exposées aux vapeurs de glycérol en utilisant notre système d'exposition de type « whole-body ». Des souris C57BL/6 mâles et femelles ont été exposées de manière aigüe pour une exposition de 6h. Bien que des changements mineurs ont été observés suivant l'exposition aigüe, l'exposition aux vapeurs de glycérol semble prévenir les effets métaboliques du jeûne. Par la suite, des souris C57BL/6 mâle et femelle, âgées de 6 ou 12 semaines, ont été exposées 2h/jour, 5 jours/semaine pour 9 semaines. Aucun changement dans le poids ou la composition en tissu adipeux n'a été observé. Nous avons montré une diminution de la tolérance au glucose chez jeunes souris mâle et femelle. Nous avons également observé une augmentation de la concentration hépatique de triglycérides et de phosphatidylcholine chez les souris femelles, sans augmentation chez les souris mâles. Aucun changement dans les marqueurs d'inflammation, de remodelage ou de stress du réticulum endoplasmique n'a été observé dans les tissus hépatiques. Les travaux présentés dans cette thèse mettent en lumière les effets de la cigarette électronique sur la santé pulmonaire et métabolique. Davantage d'études sur les effets des composantes de la cigarette électronique sont nécessaires afin de caractériser les mécanismes responsables de ces changements.The electronic cigarette market is in constant expansion. A majority of electronic cigarette users are also tobacco cigarette smokers though an increasing number of young people are starting to use electronic cigarettes without having to smoke tobacco cigarettes first. In addition to propylene glycol and glycerol, vaping liquids in electronic cigarettes contain different concentrations of nicotine and nearly 15,000 flavours are available. Glycerol is a metabolic substrate involved in the production of glucose during fasting and lipids after feeding. The impacts of electronic cigarettes on health remain to be determined. The general hypothesis of this thesis is that the use of electronic cigarettes disrupts lung and metabolic processes. The first objective of this thesis was to evaluate the effects of the variation in the electronic cigarette model as well as the composition of the vaping liquid on the size of the emitted particles generated. Using the InExpose e-cigarette extension (SCIREQ), different concentrations of nicotine, flavours and proportions of propylene glycol and glycerol were assessed. The particle size of electronic cigarette aerosols was analyzed by a Scanning Mobility Particle Sizer spectrometer (SMPS 3080, TSI Inc). We have shown that increasing electronic cigarette power increases the size of the particles emitted. We have also shown that a greater proportion of glycerol or the presence of nicotine and vanillin led to increased particle size. These changes alter the predicted pulmonary deposition of e-cigarette particles. The second objective of this thesis was to investigate the pulmonary effects of dual exposure to electronic cigarette aerosols and cigarette smoke. Exposure of female BALB/c mice to 3R4F cigarette smoke was performed in an automated whole-body system (Promech Lab AB SIU24). Exposure to electronic cigarette aerosols was carried out in a whole-body system developed in our laboratory, using a flavourless and nicotine-free vaping liquid. For both types of exposure, mice were exposed successively 2 hours/day, 5 days/week for 8 weeks. We showed that mice exposed to electronic cigarette aerosols and cigarette smoke exhibit changes in the expression of genes involved in the regulation of the circadian rhythm. We found increases in the frequency of dendritic cells, macrophages, neutrophils, B lymphocytes as well as CD4+ and CD8+ T lymphocytes in lung tissue compared to mice exposed only to cigarette smoke. Exposure to electronic cigarette aerosols also modulated immunoglobulin levels in the bronchoalveolar lavage and serum. An increase in airway resistance was observed in mice exposed to electronic cigarette aerosols, with or without concomitant exposure to cigarette smoke. The third objective of this thesis was to characterize the effects of glycerol vaping liquid aerosol inhalation on energy metabolism. Mice were exposed to glycerol aerosols using our whole-body exposure system. Male and female C57BL/6 mice were acutely exposed for 6 hours. Although only minor changes were observed, acute exposure to glycerol aerosols appears to prevent the metabolic effects of fasting. Separately, male and female C57BL/6 mice of 6- or 12-week-old, were exposed for 2 hours/day, 5 days/week for 9 weeks. No change in weight or body fat composition was observed. We showed decrease glucose tolerance of young male and female mice. We also observed an increase in hepatic triglyceride and phosphatidylcholine concentration in female mice, without effect in male mice. No changes in markers of endoplasmic reticulum stress, inflammation, or remodeling were observed in liver tissue. The work presented in this thesis highlights the effects of electronic cigarettes on lung and metabolic health. More studies on the effects of the components of electronic cigarettes are needed to further characterize the mechanisms involved in these changes.
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Pereira, Vítor Manuel. "Disorder and localization effects in correlated electronic systems." Doctoral thesis, Porto : edição do autor, 2006. http://hdl.handle.net/10216/64278.
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Morris, Nichole Leann. "Effects of simulated cataracts on speechreading." Diss., Wichita State University, 2011. http://hdl.handle.net/10057/5060.
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Watching a speaker‘s face can improve a listener‘s speech understanding, especially at poorer signal-to-noise ratios (SNRs). Little is known, however, about the effects of visual impairments on speechreading. In a series of studies, young adults‘ visual enhancement to speech intelligibility under normal vision and simulated cataract vision was tested. In Study 1, speech intelligibility was tested while Central Institute for the Deaf Everyday Speech Sentences were presented via live-voice at a fixed -13 dB SNR under normal vision and mild cataract conditions. In Study 2, speech intelligibility was tested while Speech in Noise (SIN) Sentences were presented via high luminance, recorded talker at SNRs ranging from 0 to -21 dB under normal vision and moderate-to-severe cataract vision. In Study 3, speech intelligibility was tested while SIN Sentences were presented via natural luminance, recorded talker at SNRs ranging from 0 to -21 dB under normal vision and simulated mild cataract vision. In Study 4, speech intelligibility was tested while SIN Sentences were presented via natural luminance, recorded talker at SNRs ranging from 0 to -21 dB under normal vision and simulated severe cataract vision. In Study 5, speech intelligibility was tested while SIN Sentences were presented via recorded talker at eight luminance levels using neutral density (ND) filters ranging from 0 to 4.2 ND at .6 steps under normal vision and simulated mild cataract vision. In Study 6, speech intelligibility was tested while SIN Sentences were presented via recorded talker at eight luminance levels using neutral density filters ranging from 0 to 4.2 ND at .6 steps under normal vision and simulated severe cataract vision. Participants‘ ability to use visual information to support speech understanding was significantly reduced under simulated mild cataracts and was nearly eliminated under simulated severe cataracts. This effect was observed under natural levels of luminance of the talker‘s face and was mitigated by high levels of luminance.Thesis (Ph.D.)--Wichita State University, College of Liberal Arts and Sciences, Dept. of Psychology
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Head, Ashley Lauren Rose. "Photoelectron Spectroscopy and Computational Studies of Molecules with Delocalized Electronic Structure and Extended Electronic Structure Interactions." Diss., The University of Arizona, 2011. http://hdl.handle.net/10150/203484.
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The localized model of a chemical bond has had a long and prominent role in chemistry, but situations of extended charge delocalization and dipole effects remain topics in need of greater understanding. Both orbital delocalization in isolated molecules and induced molecular dipoles in condensed phases serve to move electron density and influence the chemical and physical properties of a system. This dissertation studies these aspects of electronic structure for selected organic, inorganic, and organometallic systems by means of electronic structure calculations and photoelectron spectroscopy, which is well-suited for studying both intramolecular and intermolecular effects by providing a direct probe of orbital energies and characters. Photoelectron spectra of P₄ and AsP₃ reveal differences in the molecular symmetry and cationic state effects between the two molecules in Chapter 3. Despite these differences, AsP₃ is found to have electron delocalization and vibrational structures that are comparable to P₄. A similar study of the delocalized -system of 2H-1,2,3-triazole in Chapter 4 relates the vibrational structure in photoelectron spectroscopy data to a series of Rydberg excitations in the vacuum UV photoabsorption spectrum. Chapters 5 and 6 examine extended electronic structures in organometallic complexes. The electron delocalization and charge transfer between two Ru centers along a bridging ethynediyl ligand is studied in [CpRu(CO)₂]₂(μC≡C). Details of the Ru-alkynyl interaction were explored by comparing the spectra of CpRu(CO)₂C≡CMe with CpRu(CO)₂Cl, including the -backbonding ability of alkynyl ligands. Chapter 6 moves from the realm of intramolecular effects to intermolecular interactions to understand how surrounding media affect electronic properties of molecules. The reversal of ionization energies between the gas and solid phases of M(CO)₄dmpe and M(CO)₄dppe, where M = Mo, W, is explored with photoelectron spectroscopy. The surrounding molecular environment stabilizes the cation, resulting in this reversal that extends to core ionization energies. The variety of systems presented illustrates the wide applicability of photoelectron spectroscopy and computations to different electronic structure studies, including how gas phase results can be related to condensed phase studies. This work continues the progress of photoelectron spectroscopy from small molecules to larger molecular systems and even further to bulk systems.
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Acton, J. M. "Quantum coherence effects in electronic, photonic and atomic structures." Thesis, University of Cambridge, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.595334.
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Light propagating through a disordered dielectric exhibits mesoscopic phenomena, such as coherent back scattering. In electronic systems, equivalent phenomena have been successfully described by the non-linear s-model. Starting from Maxwell’s equation in its full vector form, it is shown that disordered photonic systems, in two and three dimensions, can also be described by a non-linear s-model. The quasi classical approximation on which this theory is based is found to be valid in a window of frequencies. Numerical simulations of these systems are consistent with the s-model predictions. The mathematical equivalence between disordered photonic and electronic systems shows that the mechanisms for localization in the electronic and photonic band gaps are the same; numerical simulations to demonstrate this are presented. An investigation into the interplay of s-wave superconductivity and itinerant antiferromagnetism in disordered metals is presented. First, a s-model to describe this interplay is derived. It is used to obtain the phase diagram for the mean field phase transition between superconductivity and antiferromagnetism. The suppression of antiferromagnetism by disorder (which is analogous to the effect of magnetic disorder on superconductivity) culminates in a quantum critical point. The bilayer proximity effect is also investigated and the density of states inside an antiferromagnet coupled to a superconductor is obtained. Feshback resonance phenomena in ultracold Fermi gases are normally described by a Fermi-Bose model in which the Feshback molecule is treated as a point-like boson. We consider an alternative model of the 6Li system, in which a spin state is shared between the open and closed channels. In contrast to the Fermi-Bose model, a critical coupling in the open channel is required to induce a Feshback resonance, even at small detuning.
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Monturet, Serge. "Inelastic effects in electronic currents at the nanometer scale." Phd thesis, Université Paul Sabatier - Toulouse III, 2008. http://tel.archives-ouvertes.fr/tel-00469906.
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This thesis deals with inelastic effects in electronic currents. We developed a time-dependent technique and show that this approach gives rich insight into electron-phonon coupling during transport. We compare our results with a time-independent technique and analyse the validity of our model. Finally, the results of a quantum chemistry calculation are presented in the framework of scanning tunneling miscroscopy (STM). We study the chemisorption of a tetrathiafulvalene molecule on a gold surface by performing the calculation of the charge transfer, the induced dipole, and the STM images using the density functional theory.
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Lu, Shi-Jian. "The significance of atmospheric effects in electronic distance measurement." Thesis, University of Leeds, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.278369.
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Flores, Jaime. "The Effects of an Electronic Feedback Sign on Speeding." Thesis, University of North Texas, 2006. https://digital.library.unt.edu/ark:/67531/metadc5280/.
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Although a handful of experiments have utilized indirect feedback in attempts to reduce speeding on roadways, fewer experiments have utilized direct feedback as a means to reduce incidences of speeding. The current study evaluated the effects of direct and individualized feedback provided by a large electronic feedback sign that displayed the speed of oncoming vehicles as they approached the sign along the roadways of a college campus. The effects of the sign were evaluated using a non-simultaneous multiple baseline experimental design employing two control conditions and intervention phase. Each condition was implemented at three sites on the college campus. The results showed that intervention produced significant decreases in both measures of vehicle speeds at each site, relative to measures collected during both control conditions.
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Van, Belle Daniel. "Computer studies of electronic polarization effects in biological systems." Doctoral thesis, Universite Libre de Bruxelles, 1992. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/212930.
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Daraszewicz, S. L. "The modelling of electronic effects in molecular dynamics simulations." Thesis, University College London (University of London), 2014. http://discovery.ucl.ac.uk/1430367/.
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This thesis describes the development and applications of the continuum-atomistic molecular dynamics (MD) model in the context of radiation damage. By extending the classical MD method to incorporate the electronic excitations represented as an electron fluid and coupled to the ions in the two-temperature (2T) formalism, we have been able to correctly capture the physics governing the atomistic dynamics under huge electronic excitations. The integrated 2T-MD model has been specifically adapted to study three types of non-equilibrium scenarios: laser excitations, swift heavy ion impacts and large-scale high energy collision cascades. Using the 2T-MD model we have estimated the impact of the electron-phonon coupling and the electronic stopping power on the primary radiation damage yield in bcc iron. We have found that the cascade dynamics and the resultant damage from 50-100 keV primary knock-on atom impacts is highly sensitive to the electronic stopping treatment at low projectile velocities, which represents the first rigorous study of this type. By examining the temporal evolution of the structure factor of laser-irradiated gold thin films, we have been able to directly compare the 2T-MD results with Bragg peaks measured by ultrafast electron diffraction and have achieved an excellent agreement between theory and experiment with no fitting parameters. This has enabled us to elucidate the melting dynamics following laser irradiation at a picosecond resolution for the first time and also to validate the two-temperature approach. To simulate semiconductors under electronic excitations, the continuum part of the 2T-MD model, which represents electrons, has been replaced by two continuum equations: one for carrier density and one for their energy, to account for the finite band-gap effects. We have applied such extended method to simulate ion tracks, which result from swift heavy ion impacts. We have achieved a very good agreement with the experimental results on the ion track radii, provided that we are free to adjust the strength of the electron-phonon coupling. We propose future studies in the field of non-equilibrium atomistic modelling. In particular, we discuss ab initio methods and further improvements to hybrid MD to study the effects of the interatomic potential changes in response to high electronic excitations.
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Parada-Valdes, Lorena. "The effects of intrusiveness on protective details." abstract and full text PDF (UNR users only), 2009. http://0-gateway.proquest.com.innopac.library.unr.edu/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:1472971.
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Thesis (Master of Justice Management (M.J.M.))--University of Nevada, Reno, 2009."December, 2009" Includes bibliographical references (leaves 33-46). Online version available on the World Wide Web.
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Ellingham, Tim John. "Raman amplification and performance altering effects." Thesis, Aston University, 2006. http://publications.aston.ac.uk/8024/.
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This thesis presents an experimental investigation into several applications of the Raman scattering effect in communication optical fibres as well as how some of these applications can be modified to enhance the resulting performance. The majority of the work contained within is based on laboratory results using many commercially available components. The results can be divided into and presented in three main parts: Firstly, a novel application of a known effect is used to broaden Raman pump light in order to achieve a more continuous distribution of gain with respect to wavelength. Multiple experimental results are presented, all based around the prior spreading of the pump spectrum before being used in the desired transmission fibre. Gathered results show that a notable improvement can be obtained from applying such a technique along with the scope for further optimisation work. Secondly, an investigation into the interaction between the well known effect of Four Wave Mixing (FWM) and Raman scattering is provided. The work provides an introduction to the effect as well commenting on previous literature regarding the effect and its mitigation. In response to existing research experimental results are provided detailing some limitations of proposed schemes along with concepts of how further alleviation from the deleterious effects maybe obtained. Lastly, the distributed nature of the Raman gain process is explored. A novel technique on how a near constant distribution of gain can be employed is implemented practically. The application of distributed gain is then applied to the generation of optical pulses with special mathematical properties within a laboratory setting and finally the effect of pump noise upon distributed gain techniques is acknowledged.
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Hessami, Pilehrood Saeid. "Electronic properties of semiconductor nanostructures under terahertz radiation." Access electronically, 2006. http://www.library.uow.edu.au/adt-NWU/public/adt-NWU20061026.162405/index.html.
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Boda, Pranav. "Effects of global warming on transmission line sag." Thesis, Wichita State University, 2012. http://hdl.handle.net/10057/5377.
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Global warming has forced the power industry to adapt its infrastructure and develop technology in order to mitigate the effects and reduce the extent to which it will affect the operation of the electrical grid. With this goal in mind, the project attempts to quantify the effect of global warming on transmission line sag. First, a climate model that could predict temperature data for the time period (2001-2100) was needed. Next, a relationship between temperature and electricity demand needed to be quantified. Using this relationship and the temperature values generated by the climate model, the predicted electricity demand values were calculated for the examined time period. Since the voltage at which power is transported remains constant, the rate at which power is delivered will be given by the current flowing through the conductor. Using the estimated current values, the temperature of the conductor was calculated. This value is then used to calculate incremental sag due to the additional electrical demand.
The calculated incremental sag is then plotted across time to show the increase in sag as temperatures increase. The plots also show various spikes in transmission line sag values ranging from less than an inch to just over two inches over the examined time period which does not significantly affect the operation of the grid. However, the project was performed using ideal values and is only a best case scenario. Overall, the project was successful in establishing that a relationship between global warming and transmission sag does exist, and that it needs to be addressed during future infrastructure planning.Thesis (M.S.)--Wichita State University, College of Engineering, Dept. of Electrical Engineering and Computer Science
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Greenwald, Ashley E. "Effects of discrimination abilities on functional analysis outcomes." abstract and full text PDF (UNR users only), 2009. http://0-gateway.proquest.com.innopac.library.unr.edu/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:1472954.
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Bessis, Charlotte. "Quantum interference and thermoelectric effects in molecular junctions." Thesis, Sorbonne Paris Cité, 2016. http://www.theses.fr/2016USPCC140/document.
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Cette thèse rapporte les mesures de transport réalisées sur des jonctions moléculaires à l'état solide large échelle, mettant en évidence des effets d'interférence quantique. Le premier chapitre pose les bases théoriques de ce phénomène et introduit le formalisme des fonctions de green hors équilibre adapté à la description du couplage molécules/interfaces métalliques. Le second chapitre présente l'état de l'art expérimental dans ce domaine et résume les principales expériences ayant permis de mettre en évidence des effets d'interférences à l'échelle moléculaire. Le troisième chapitre décrit les étapes de fabrication mises en place pour construire les dispositifs mesures pendant ce travail de thèse. Les résultats expérimentaux obtenus sur les mesures de conductance des jonctions moléculaires sont décrits dans le quatrième chapitre et compares a plusieurs modèles théoriques qui confirme la présence d'interférences quantiques. Le dernier chapitre aborde les effets de thermoélectricité qui peuvent avoir lieu dans ces jonctions en présence d'interférenceThis thesis reports the transport measurement performed on large scale solid state molecular junctions, highlighting quantum interference effect. First chapter set the theoretical basis of such a phenomenon and introduces the out of equilibrium green's functions formalism which is adapted to the description of coupling molecules/metallic interfaces. Second chapter presents the corresponding experimental state of the art and summarizes the experiments that have contributed to highlight interference effect at the molecular scale. Third chapter describes the fabrication steps optimized to build the devices measured during the thesis work. Experimental results obtained on conductance measurements are described and compared to several theoretical models that confirm the presence of quantum interference. Last chapter deals with thermoelectric effect that can occur in presence of interference
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Byrne, Christopher J. "The effect of molecular geometry on the electronic effects of the azo and azoxy groups." Thesis, University of Canterbury. Chemistry, 1986. http://hdl.handle.net/10092/8551.
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The effect of molecular geometry on the electronic effect of the azo and azoxy groups has been examined in two
ways.
In Part I the pKa's of a series of substituted benzoic and phenylacetic acids were measured in 50% 0.1MKCl-ethanol at 25%. The results were interpreted in terms of the
Hammett equation to derive σm, σp and σp° substituent constants. In addition the rates of solvolysis of a series of aryldimethylcarbinyl chlorides were measured in 87.5%, 80% and 72.5% acetone-water at 25°, with the results being interpreted in terms of σ p+ substituent constants. The electronic effect of the following groups was investigated in this way; phenylazo, (σm, σp, σp°, σp+); arylazo, (σp+); 2,6-dimethylphenylazo, (σp+); t-butylazo, (σm, σp, σp+); phenyl-ONN-azoxy, (σm, σp, σp+); and phenyl-NNO-azoxy, (σm, σp). The results suggested that the phenylazo group was in a coplanar configuration with respect to the ring bearing the reaction site. The electronic effect of these substituents in the non-planar configuration was also investigated by determining the effect on σp and σp+ when the coplanar configuration was hindered by two flanking methyl groups. The results showed that the non-planar configuration is intrinsicially more electron donating than the coplanar one. The relevance of these results to the different reported assessments of the activating power of the phenylazo group in electrophilic aromatic substitution is discussed.
In Part II the ¹³C n.m.r. spectra of a series of 3' and 4'- substituted 2,6-dimethylazobenzenes have been measured in deuterochloroform. The effect of substituents in one ring on the chemical shift of the carbons in the other were interpreted in terms of their inductive and resonance effects by means of a dual substituent parameter analysis. The results showed that relative to the previously reported unhindered azobenzene series, a significant increase in the sensitivity to both inductive and resonance effects was observed at all positions. Possible explanations for this effect in terms of the modes of operation of the inductive and resonance effects are discussed.
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Bordacchini, Ivan. "Discerning between thermal and electronic effects in plasmonenhanced organic reactions." Doctoral thesis, Universitat Politècnica de Catalunya, 2020. http://hdl.handle.net/10803/670350.
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Since the pioneering work of Fujishima and Honda on titanium dioxide, TiO2, for the electrochemical photolysis of water under ultraviolet (UV) irradiation, semiconductor-based photocatalysis and photovoltaics have become a rapidly growing field of investigation.
However, UV light accounts for only 4% of the solar spectrum, whereas the visible light represents 42% of the total solar radiation. Therefore, the scientific community focused their efforts on the optimization and extension of the absorption spectrum of semiconductor-based materials to the visible region of the solar spectrum. Well-established techniques include doping of the semiconductor or the deposition of a different element or substance on the surface of the material.
Since 2004, the deposition of plasmonic nanoparticles (NPs) on semiconductors emerged as a possible solution to generate energetic electrons capable of driving reactions under visible irradiation. Since then, numerous contributions have been published in the field of plasmon-enhanced photocatalysis with relevant applications in water splitting, organic synthesis, and photovoltaics.
In the field of heterogeneous photocatalysis, plasmon-generated energetic electrons were widely accepted as responsible for the observed catalytic effect of plasmonic NPs. Recently, several scientific contributions have questioned the actual mechanism triggering plasmonenhanced reactions, hypothesising that thermal effects are instead the predominant factor that influences the activity of a plasmonic catalyst.
In this work, we aimed at differentiating between the thermal and electronic effects of plasmonic NPs in a test reaction—the reductive coupling of nitrobenzene to azobenzene—under irradiation with 532 nm and/or 875 nm lasers. Moreover, we also aimed at developing a methodology that could be easily replicated in other laboratories and used as a benchmark test for plasmon-enhanced reactions run in solution.
We optimized the size and shape of AuNPs plasmonic catalysts to obtain materials with different absorption in the visible and near-infrared (NIR) region to tune the electronic and thermal effects of the catalyst. The activity of the synthesised catalysts for the test reaction was compared with the activity of the Gold World Council reference catalyst type A.
Characterization of the synthesised Au/TiO2 catalyst with diffuse reflectance measurements evidenced that the presence of small amounts of AuNPs did not modify the band gap position of the support, hence suggesting that, under visible light irradiation, the catalysis occurred on the surface of the AuNPs. The determination of the enthalpy of activation for each step of the reaction showed that the second step of the reaction was strongly influenced by the 532 nm laser irradiation. Indeed, our calculations demonstrated an energy difference between the illuminated and the dark reactions in the first step of reaction of 1.1 Kcal moll!’’ whereas the one for the second step was 5.9 Kcal mol!’’.
We further analysed the results of designed experiments running the test reaction in the presence of two catalysts differing by the shapes of the AuNPs and under different laser sources and irradiances. The results were processed to obtain predictive phenomenological models for the intermediate and the product of the reaction, azoxybenzene and azobenzene, respectively.
The obtained models allowed to confirm that the investigated reaction was triggered by electronic effects and that the contribution of thermal effects, generated by the electron-phonon decay of elongated AuNPs, was not significantly influencing the reaction outcome.A partir del trabajo pionerito de Fujishima y Honda sobre el dióxido de titanio, TiO2, para la fotólisis electroquímica de agua bajo irradiación ultravioleta (UV), la fotocatálisis basada en semiconductores y la energía fotovoltaica se han convertido en un campo de investigación en rápido crecimiento. Sin embargo, la luz ultravioleta representa solo el 4% del espectro solar, mientras que la luz visible representa el 42% de la radiación solar total. Por lo tanto, la comunidad científica centró sus esfuerzos en la optimización y extensión del espectro de absorción de materiales, basados en semiconductores, a la región visible del espectro solar. Las técnicas establecidas incluyen el dopaje del semiconductor o la deposición de un elemento o sustancia diferente sobre la superficie del material. Desde 2004, la deposición de nanopartículas plasmónicas (NP) en semiconductores surgió como una posible solución para generar electrones energéticos capaces de impulsar reacciones bajo irradiación visible. Desde entonces, se han publicado numerosas contribuciones en el campo de la fotocatálisis por medio de la excitación de plasmones con aplicaciones relevantes en la disociación de agua, síntesis orgánica y energía fotovoltaica. En el campo de la fotocatálisis heterogénea, los electrones energéticos generados por plasmón fueron ampliamente aceptados como responsables del efecto catalítico observado de las NP plasmónicas. Recientemente, varias contribuciones científicas han cuestionado el mecanismo real que desencadena las reacciones catalizadas por plasmón, con la hipótesis de que los efectos térmicos son, en cambio, el factor predominante que influye en la actividad de un catalizador plasmónico. Nuestro objetivo fue diferenciar entre los efectos térmicos y electrónicos de los NP plasmónicos en una reacción de prueba, el acoplamiento reductor de nitrobenceno a azobenceno, bajo irradiación con láseres de 532 nm y/o 875 nm. Además, también nos propusimos desarrollar una metodología que pudiera replicarse fácilmente en otros laboratorios y usarse como prueba de referencia para reacciones en solución donde se explota la excitación de plasmones. En este trabajo se ha optimizado el tamaño y la forma de las partículas de oro, AuNPs, para obtener catalizadores caracterizados de diferente absorción en la región visible e infrarroja cercana (NIR) para controlar y seleccionar los efectos electrónicos y térmicos del catalizador. La actividad de los catalizadores sintetizados para la reacción de prueba se comparó con la actividad del catalizador de referencia tipo A del Gold World Council. La caracterización del catalizador de Au/TiO2 sintetizado con mediciones de reflectancia difusa evidenció que la presencia de pequeñas cantidades de AuNP no modificó la posición de la banda prohibida del soporte, lo que sugiere que, bajo irradiación de luz visible, la catálisis se produjo en la superficie de los AuNP. La determinación de la entalpía de activación para cada paso de la reacción mostró que el segundo paso de la reacción estaba fuertemente influenciada por la irradiación láser de 532 nm. De hecho, nuestros cálculos demostraron una diferencia de energía entre las reacciones iluminadas y oscuras en el primer paso de reacción de 1.1 Kcal mol!’, mientras que la del segundo paso fue de 5.9 Kcal mol!’ Además, se analizaron los resultados de experimentos diseñados explotando principios de estadística y ejecutando la reacción de prueba en presencia de dos catalizadores que se diferencian por las formas de las AuNP y bajo diferentes fuentes de láser. Los resultados se procesaron para obtener modelos fenomenológicos predictivos para el intermedio y el producto de la reacción, azoxibenceno y azobenceno, respectivamente. Los modelos obtenidos permitieron confirmar que en la reacción investigada los efectos electrónicos son predominantes con respecto a la contribución de los efectos térmicos, generados por interacción electrón-fonón de los AuNP cilíndricos, no influyó significativamente en el resultado de la reacción
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Kleimann, Tobias. "Interaction effects in electronic transport through one-dimensional quantum dots." [S.l. : s.n.], 2003. http://deposit.ddb.de/cgi-bin/dokserv?idn=967921325.
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Ormerod, Robert Mark. "Structural and electronic effects in the catalytic chemistry of palladium." Thesis, University of Cambridge, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.335746.
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Cho, Hyuksoo. "Determinants and effects of electronic intermediary use in export marketing." Online access for everyone, 2004. http://www.dissertations.wsu.edu/Dissertations/Spring2004/h%5Fcho%5F050404.pdf.
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West, Allen M. "Effects of dislocations on electronic properties of III-nitride materials." [Gainesville, Fla.] : University of Florida, 2005. http://purl.fcla.edu/fcla/etd/UFE0009281.
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Day, Amanda Michele. "Generation Y physical activity: the physiologic effects of exergaming." Thesis, Wichita State University, 2012. http://hdl.handle.net/10057/5385.
Full textAbstract:
Childhood obesity is on the rise, and many critics claim that environmental factors, such
as screen-based media, are a contributing factor to this epidemic. Video games have gained
popularity among this age group, especially exergames, which have researchers pondering the
physiological effects of playing exergames. The purpose of this study is to examine the
differences in heart rate achieved and maximum heart rate achieved between three exergaming
systems, and to analyze the intensity level achieved while playing exergames. Twenty males and
females ages 8-12 were in this study. Participants were allowed three sessions to become
familiarized with equipment and were allowed to play three game systems: (1) Nintendo Wii, (2)
Dance Dance Revolution (DDR), (3) Xbox Kinect. Heart rate monitors were worn on the wrist
by each participant and were used to record heart rates during six exergaming sessions.
Participants played one type of exergaming system for 30 minutes each session, collecting heart
rate seven times. Heart rate data were compared to baseline measures, between the threeexergaming
systems, and to heart rate thresholds of 50 percent and 70 percent of maximum heart
rate. Repeated Measures ANOVA did not show significance for heart rate achieved and heart
rate ranges achieved (p=0.563, p= 0.738 respectively). Sixty-four percent of participants
achieved heart rates that ranged between set thresholds of 50 percent and 75 percent on all three
exergaming systems. Thus, exergaming can be used as physical activity to supplement other
forms of physical activity.Thesis (M.Ed.)--Wichita State University, College of Education, Dept. of Human Performance Studies
40
Juza, Stephen Paul. "The effects of student engagement on high school mathematics." Thesis, Wichita State University, 2013. http://hdl.handle.net/10057/7037.
Full textAbstract:
My thesis focuses on the impact student engagement has on tenth grade mathematic test scores. Using secondary data from the Education Longitudinal Survey, I examined the math scores of 7,480 tenth graders in 2004. I predicted that students who were more engaged in their school environment will have higher test scores. In addition to engagement, I examine the impact that social networks and parental influences play in these math scores. I predicted that school engagement, school factors, parental influences, and peer relationships would play a role in determining tenth grade math scores. In addition, I predicted that socioeconomic status (SES) would play a role in determining extracurricular activities and parental involvement.
Overall, many of the hypotheses tested were supported, indicating that increasing student engagement with their school will have a positive impact on their math scores. Parental involvement had a more positive impact on math scores among higher SES families, particularly because the social expectations and network surrounding the students. SES had a significant impact on math scores by impacting the school, the expectations, and the parental influence on the child. Peer influences researched here had a negligible impact on math scores. Future research from here needs to focus on the implementation of student engagement activities and the effectiveness of these activities.Thesis (M.A.)--Wichita State University, Fairmount College of Liberal Arts and Sciences, Dept. of Sociology.
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Asmar, Mahmoud M. "Electronic and Spin Transport in Dirac-Like Systems." Ohio University / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1437564830.
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Brown, Christopher Michael. "Specific effects of action video games on perception and attention." Diss., Wichita State University, 2012. http://hdl.handle.net/10057/5352.
Full textAbstract:
Many research studies have
established that playing
action video games can
lead
to
visual
attention
and
perception
benefits
for
the
player.
This
dissertation
pioneers
the
use
of
custom
designed
video
game
levels
to
determine
if
a
single
aspect
of
action
video
game
play
has
specific
effects
on
the
player.
In
the
following
studies,
specific
aspects
of
action
video
games
can
indeed
be
isolated
and
thus
potentially
used
as
training
tools
for
targeted
perceptual
benefits.
Experiment
1
demonstrates
that
just
two
hours
of
training
in
a
custom
designed
video
game
world
that
emphasizes
friend
vs.
foe
discrimination
benefits
players’
ability
to
focus
on
relevant
visual
information,
and
leads
to
marginally
decreased
flanker
interference
and
marginally
improved
filtering
capacity.
Experiment
2
examines
the
beneficial
effects
of
dispersed
vs.
narrowly
focused
attention
in
a
second
custom
designed
video
game
world.
After
two
hours
of
game
play,
players
in
the
dispersed
attention
condition
significantly
increased
their
visual
working
memory
capacity
and
ability
to allocate
attention
to
peripheral
items.Thesis (Ph.D.)--Wichita State University, College of Liberal Arts and Sciences, Dept. of Psychology
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Epps, Elizabeth J. "Effects of exercise on balance and function in Parkinson's patients." Thesis, Wichita State University, 2013. http://hdl.handle.net/10057/6814.
Full textAbstract:
INTRODUCTION: Parkinson's disease (PD) is a disturbance of the neurotransmitter dopamine in the brain. Dopamine aids the muscle in normalization of sequential muscle movements, muscle tone, and automatic learned movements; balance is a combination of visual, vestibular and mechanoreceptors that factor into body position while standing. This study evaluated the effects of exercise on postural balance and strength in people diagnosed with Parkinson's disease. METHOD: Seven PD patients (5 male; 2 female) aged 55-76 participated in an exercise program consisting of progressive strength and balance training 3 days per week for 12 weeks. Balance was measured using the Biodex Balance System. Functional strength, endurance and flexibility were measured utilizing a battery of tests, including arm curls, chair stand, up and go, 6-minute walk, back scratch, and sit-and-reach. RESULTS: Pre to post comparisons found no significant difference in arm curl (P= .071), chair rise (P =.586), up and go (P= .906), 6-minute walk (P= .619), back scratch (P=.257), or sit and reach (P= .604). The Biodex Balance test showed no significant difference in anterior/posterior sway (P= .456), medial/lateral sway (P= .248), or stability index (P= 0.82). CONCLUSION: There was no difference after 12 weeks of postural balance and progressive strength training classes. Future testing should involve a longer training period, a greater number of participants, and a control group.Thesis (M.Ed)--Wichita State University, College of Education, Dept. of Human Performance Studies
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Knaub, Daniel P. "Examining the effects of tabloid discourse(s) /." Electronic version (PDF), 2007. http://dl.uncw.edu/etd/2007-1/knaubd/danielknaub.pdf.
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Drake, Rachel Mari’. "Effects of severe and persistent mental illness on maximal aerobic capacity." Thesis, Wichita State University, 2011. http://hdl.handle.net/10057/3950.
Full textAbstract:
Maximal aerobic capacity (VO2max) is a good indicator of overall health and is commonly
measured in the general population, but often goes overlooked in individuals with SMI.
Previous studies involving exercise and SMI focus mainly on self-perception and mood.
Only one study has measured the VO2max in this select population while promoting exercise
and dietary changes. Purpose: To assess the maximum aerobic capacity, weight, and body
fat percentage (BF%) in individuals with SMI. Methods: Weight, BF%, and VO2max were
measured prior to wellness intervention (pre) and following wellness intervention (post).
Forty-nine individuals (27=male, 22=female) with a mean age of 43±13.20 years of age and
a diagnosis meeting the criteria for severe and persistent mental illness (SMI) were
assessed. SMI classification among the subjects as follows: schizophrenia (n=11), bipolar
disorder (n=17), schizoaffective disorder (n=14), major depressive disorder (n=7).
Results: No significant difference was observed between baseline and endpoint
measurements of BF% in all diagnoses except MDD. Males with MDD benefited from a
wellness intervention with a significantly lower BF% (p(.036);p<0.05). A wellness
intervention did not increase in the VO2max in individuals with SMI (p(.0358);p<0.05).
Individuals with SMI continually rated in the very poor to poor section for VO2max.
Conclusion: Individuals with SMI tend to have low aerobic capacity and high body fat
percentage. Individuals in the current study did not benefit from a wellness intervention in
terms of BF% and VO2max except males with MDD. Males with MDD significantly lowered
their BF% following a wellness intervention.Thesis (M.Ed.)--Wichita State University, College of Education, Dept. of Human Performance Studies.
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Oswald, Dana R. "Effects of rhythmic movements on students’ behaviors, emotions and academic growth." Thesis, Wichita State University, 2010. http://hdl.handle.net/10057/3320.
Full textAbstract:
This study investigated the effects of rhythmic movements on students' behaviors, emotions, and academic growth. The study concentrated on a fourth grade class from a Title 1 building, where the majority of students came from poverty, and were scoring below grade level in reading and mathematics. A series of ball exercises were implemented in the classroom for 15-20 minutes daily for nine weeks. The behavior, emotions and academic growth of the students were monitored and recorded. Academically, reading scores significantly increased as compared with the control group. Results also showed a decrease in negative behaviors from 35 interruptions per hour to 5 and an increase in student engagement by 15%. Throughout this study, students also claimed to feel less stressed and have fewer worries while at school.Thesis (M.Ed.)--Wichita State University, College of Education, Dept. of Curriculum and Instruction.
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Berry, Bobby D. "Effects of upper body resistance while treadmill walking in older adults." Thesis, Wichita State University, 2013. http://hdl.handle.net/10057/6804.
Full textAbstract:
Individuals have been adding hand-weights to walking regimens to increase caloric expenditure and arm strength. This is typically contraindicated due to changes in mechanics caused by weighted swinging arms. To address this safety concern we used a new commercial treadmill with a modified support rail that allowed a resistance to be applied to the upper body without the force of the swinging hand-weights. PURPOSE: The purpose of this study was to assess functional strength, balance and walking speed on older adults, while walking on a modified treadmill that applied intermittent upper-body static presses and see the effects. METHODS: Five older adults (age: 75 plus-minus 14 yrs) males(n= 2) and females (n=3) completed four weeks of exercise trials twice per week. (WALK + RES) were tested on the same days. The WALK + RES trial used a specially designed treadmill equipped with an adjustable weighted sled apparatus. Subjects walked at their desired speed throughout the trial starting at a grade of 0% which was not increased during the ten minutes. The WALK + RES trial incorporated an upper body static press against a weighted sled set at 5% of their body weight as resistance. During the WALK + RES trial, subjects completed ten minutes of 30 second static presses separated by 30 seconds of upper-body relaxation. RPE was recorded at the ten minute trial using the Borg scale, respectively. At the start and finish of the four weeks balance, & strength were retested to see if any gains were made. RESULTS: Strength gains were made on everyone tested and balance gains were also made. CONCLUSION: Adding upper-body resistance to walking significantly increases workload. The modified treadmill allows participants to fix their hands to a rail, similar to pushing a cart addressing the safety concerns of lumbar rotation caused by hand-weights Adding functional resistance upper-body exercise during walking may be an effective mode of exercise to increase strength, balance and activities of daily living in special populations.Thesis (M.Ed)--Wichita State University, College of Education, Dept. of Human Performance Studies
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Compton, Meredith. "Parent involvement in pre-kindergarten and the effects on student achievement." Thesis, Wichita State University, 2013. http://hdl.handle.net/10057/10630.
Full textAbstract:
An ever-present achievement gap has been found among students and their peers. Educational research and literature have found that the growing gap is due in part to a lack of parent involvement in their students' education and academic performance. The purpose of this study is to investigate how parent involvement affects student achievement and academic success in Pre-Kindergarten. It is hypothesized that parents who display higher levels of involvement will have children that perform better academically. The participants in this study included 38 preschool children and their parents. The researcher utilized a curriculum based measurement, AIMSweb, and IGDI's (Indicators of Individual Growth and Development for Infants and Toddlers), a pre-k assessment measure used to monitor and assess early literacy development in preschool children. A modified version of the Parent Involvement Project Questionnaire (PIPQ) was also used to determine if there is a positive correlation between parent involvement and student achievement. Results of the study indicate that student achievement is not statistically correlated with any of the scales from the parental involvement survey. Because the results were based on self-report and included a relatively small sample size, the outcomes of the study may not align with the majority of published studies pertaining to parent involvement and student achievement, due to its subjective nature. Or, perhaps for some students, there may be other factors that are more influential than parent involvement. Implications and further research are discussed.Thesis (M.A.T.)--Wichita State University, College of Education, Dept. of Curriculum and Instruction
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Razinobakht, Seyed Alireza. "Silanization effects of carbon black nanoparticles on curing kinetics of nanocomposites." Thesis, Wichita State University, 2014. http://hdl.handle.net/10057/10973.
Full textAbstract:
This study presents the development of a nanocomposite using carbon black and Epoxy Resin 828 to improve the curing kinetics of nanocomposite. There is little to no data on curing kinetics of silanized carbon nanocomposite. In this study, carbon black was modified using silanization process to improve its dispersion in epoxy resin which resulted in a change of curing kinetics. Silanization is a surface modification technique to improve carbon black stability and decrease agglomeration of carbon black during the mixing process. Different methods such as stability in acetone, Fourier Transform Infrared Spectrometer (FTIR), and Scanning Electron Microscopic (SEM) were used to confirm the silanization process of carbon black. Differential Scanning Calorimetry (DSC) was used to test the curing kinetics of carbon black nanocomposite. In order to find the curing kinetics of nanocomposite using DSC, finding a baseline was essential. Epoxy resin 828 and 12%wt curing agent were mixed and samples were tested in DSC at different temperatures to find the baseline. After finding the baseline, nanocomposite was prepared using unmodified and modified (silanized) carbon black at 2%, 4% and 8% weight percentage of carbon black. Curing kinetics of modified and unmodified carbon black nanocomposite revealed that curing temperature of 110 degrees F for modified CB nanocomposite had a higher Degree of Cure (DOC) than unmodified. Curing kinetics for 220 degrees F for unmodified and modified did not show significant differences, since curing occurred faster at a higher temperature. However, curing time was shorter for modified CB than unmodified. Acceleration in curing kinetics could have a positive effect on processing of nanocomposites by decreasing cure time at a lower temperature. This study may open up some new opportunities for curing kinetics of various nanoparticle nanocomposites used in many nanocomposite manufacturing industries.Thesis (M.S.)--Wichita State University, College of Engineering, Dept. of Mechanical Engineering
50
Lear, Benjamin James. "The effects of electronic delocalization in highly coupled mixed valence systems." Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC campuses, 2007. http://wwwlib.umi.com/cr/ucsd/fullcit?p3273182.
Full textAbstract:
Thesis (Ph. D.)--University of California, San Diego, 2007.Title from first page of PDF file (viewed August 31, 2007). Available via ProQuest Digital Dissertations. Vita. Includes bibliographical references (p. 138-146).