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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
241

NANOPLASMONIC EFFICACY OF GOLD TRIANGULAR NANOPRISMS IN MEASUREMENT SCIENCE: APPLICATIONS RANGING FROM BIOMEDICAL TO FORENSIC SCIENCES

Thakshila Liyanage (8098115) 11 December 2019 (has links)
<p>Noble metal nanostructures display collective oscillation of the surface conduction electrons upon light irradiation as a form of localized surface plasmon resonance (LSPR) properties. Size, shape and the refractive index of surrounding environment are the key features that controls the LSPR properties. Surface passivating ligands have the ability to modify the charge density of nanostructures to allow resonant wavelength to match that of the incident light, a phenomenon called “plasmoelectric effect,”. According to the drude model Red and blue shifts of LSPR peak of nanostructures are observed in the event of reducing and increasing charge density, respectively. However, herein we report unusual LSPR properties of gold triangular nanoprisms (Au TNPs) upon functionalization with para-substituted thiophenols (X-Ph-SH, X = -NH<sub>2</sub>, -OCH<sub>3</sub>, -CH<sub>3</sub>, -H, -Cl, -CF<sub>3</sub>, and -NO<sub>2</sub>). Accordingly, we hypothesized that an appropriate energy level alignment between the Au Fermi energy and the HOMO or LUMO of ligands allows delocalization of surface plasmon excitation at the hybrid inorganic-organic interface, and thus provides a thermodynamically driven plasmoelectric effect. We further validated our hypothesis by calculating the HOMO and LUMO levels and also work function changes of Au TNPs upon functionalization with para substituted thiol. We further utilized our unique finding to design ultrasensitive plasmonic substrate for biosensing of cancer microRNA in bladder cancer and owe to unpresidential sensitivity of the developed Au TNPs based LSPR sensor, for the first time we have been utilized to analysis the tumor suppressor microRNA for more accurate diagnosis of BC. Additionally, we have been advancing our sensing platform to mitigate the false positive and negative responses of the sensing platform using surface enhanced fluorescence technique. This noninvasive, highly sensitive, highly specific, also does not have false positives technique provide strong key to detect cancer at very early stage, hence increase the cancer survival rate. Moreover, the electromagnetic field enhancement of Surface-Enhanced Raman Scattering (SERS) and other related surface-enhanced spectroscopic processes resulted from the LSPR property. This dissertation describes the design and development of entirely new SERS nanosensors using flexible SERS substrate based on unique LSPR property of Au TNPs and developed sensors shows excellent SERS activity (enhancement factor = ~6.0 x 106) and limit of detection (as low as 56 parts-per-quadrillions) with high selectivity by chemometric analyses among three commonly used explosives (TNT, RDX, and PETN). Further we achieved the programable self-assembly of Au TNPs using molecular tailoring to form a 3D supper lattice array based on the substrate effect. Here we achieved the highest reported sensitivity for potent drug analysis, including opioids and synthetic cannabinoids from human plasma obtained from the emergency room. This exquisite sensitivity is mainly due to the two reasons, including molecular resonance of the adsorbate molecules and the plasmonic coupling among the nanoparticles. Altogether we are highly optimistic that our research will not only increase the patient survival rate through early detection of cancer but also help to battle the “war against drugs” that together is expected to enhance the quality of human life. </p> <p> </p>
242

Amorçage en détonation des explosifs hétérogènes de type coulé fondu : Etablissement de corrélations entre microstructure et réactivité / Detonation initiation of heterogeneous melt-cast high explosives : Microstructure and reaction rate correlations

Chuzeville, Vincent Pierre 20 October 2016 (has links)
Ce travail de thèse porte sur les mécanismes d’amorçage en détonation par choc des explosifs solides de type coulé-fondu. Les explosifs solides sont des matériaux hétérogènes constitués de grains de matière énergétique dans un liant pouvant être lui-même énergétique. Si l’existence des points chauds, sites préférentiels d’initiation des réactions chimiques à l’échelle locale, est largement reconnue, la topologie de la croissance des réactions, et l’influence de la microstructure sur cette dernière n’est que peu étudiée dans les explosifs coulés-fondus. Deux familles d’explosifs ont été retenues pour cette étude : les hexolites, mélanges de grains d’hexogène (RDX) et d’un liant trinitrotoluène (TNT) et les ontalites, composées d’oxynitrotriazole (ONTA) et de TNT. Les recherches se sont orientées autour du triptyque : caractérisation – expérimentations – modélisation.Un important travail de compilation et de ré-exploitation de données issues de la littérature, associé à une modélisation des équations d’état des explosifs purs, ont permis de définir des lois permettant de calculer le comportement de ces derniers sous choc. Ces lois ont ensuite été validées par une méthode de mélange sur différentes compositions coulées-fondues et composites. Parallèlement, la microstructure des compositions d’étude a également été caractérisée via des mesures de granulométrie et de microtomographie, inédites sur ce type d’explosif.Des expérimentations d’impact plan soutenu ont été réalisées afin d’établir les diagrammes de marche des ondes de choc réactives, permettant de relier la profondeur de transition à la détonation à la pression de sollicitation. Elles ont permis de mettre en lumière l’influence de la microstructure sur la sensibilité au choc de deux hexolites et d’acquérir des données sur deux ontalites. L’utilisation de deux métrologies innovantes, la radio-interférométrie à 94 GHz et les fibres optiques à réseau de Bragg, a permis de mesurer la transition choc – détonation (TCD) de façon continue avec une résolution inédite. Enfin des essais d’impact plan non soutenu ont été réalisés à des fins de validation.Un modèle de TCD est proposé. Ce dernier, basé sur une approche de germination-croissance des fronts de déflagration à l’échelle locale, permet de prendre en compte la microstructure des explosifs. Ces travaux semblent mettre en évidence l’influence de la fracturation des grains d’explosif sous choc, qu’il conviendra d’étudier dans le futur. Enfin, une étape de terminaison des réactions lors de la TCD, associée à des calculs thermocinétiques détaillés, a été étudiée. / This study deals with the detonation initiation by shock of condensed melt-cast high explosives. Solid explosives are heterogeneous materials, made of energetic material grains in a binder, which can be energetic itself. If the existence of hot-spots, preferred initiation sites for chemical reaction at the local scale, is widely recognized, the reaction growth topology, and the microstructure influence, are poorly known for melt-cast explosives. We study here two melt-cast explosive families: hexolites, a mix of hexogen (RDX) grains and trinitrotoluene (TNT) binder, and ontalites made of nitrotriazolone (NTO) and TNT. This study has been focused on the triptyque: characterization - experimentations - modeling.An important work of compilation and re-exploitation of literature data, combined with pure explosives’ equation of state modeling, allowed us to define laws to calculate the explosives’ comportment under a shock solicitation. These ones have been validated, thanks to a mixing method, on different melt-cast and cast-curd plastic bonded explosives. At the same time, the compositions’ microstructure has been also characterized via granulometry measurements and microtomographies, never published for this type of explosive.Plate impact tests have been performed in order to establish the reactive shock trajectory of these compositions, allowing us to determine the relation between the run-distance of detonation and the input pressure. It brought the microstructure influence on hexolite shock sensitivity to light, and gave us some first results for ontalites. The use of continuous and innovative measurements, as microwave interferometry and chirped fiber Bragg gratings, allowed us to study the shock to detonation transition (SDT) with a resolution never seen before. Finally, non-sustained plate impact test have been performed for a validation purpose.A SDT model is proposed. Based on a germination-growth approach of deflagration fronts at the local scale, it takes into account the explosive’s microstructure. This work seems to show the grain fragmentation under shock influence, point we will have to study in the future. Finally, a completion step of reactions, associated with chemical kinetics calculations, has been studied.
243

Functional hybrid materials for the optical recognition of nitroaromatic explosives involving supramolecular interactions

Salinas Soler, Yolanda 02 September 2013 (has links)
La presente tesis doctoral titulada ¿Materiales funcionales híbridos para el reconocimiento óptico de explosivos nitroaromáticos mediante interacciones supramoleculares¿ se basa en la combinación de principios de Química Supramolecular y de Ciencia de los Materiales para el diseño y desarrollo de nuevos materiales híbridos orgánico-inorgánicos funcionales capaces de detectar explosivos nitroaromáticos en disolución. En primer lugar se realizó una búsqueda bibliográfica exhaustiva de todos los sensores ópticos (cromogénicos y fluorogénicos) descritos en la bibliografía y que abarca el periodo desde 1947 hasta 2011. Los resultados de la búsqueda están reflejados en el capítulo 2 de esta tesis. El primer material híbrido preparado está basado en la aplicación de la aproximación de los canales iónicos y, para ello, emplea nanopartículas de sílice funcionalizadas con unidades reactivas y unidades coordinantes (ver capítulo 3). Este soporte inorgánico se funcionaliza con tioles (unidad reactiva) y una poliamina lineal (unidad coordinante) y se estudia el transporte de una escuaridina (colorante) a la superficie de la nanopartícula en presencia de diferentes explosivos. En ausencia de explosivos, la escuaridina (color azul y fluorescencia intensa) es capaz de reaccionar con los tioles anclados en la superficie decolorando la disolución. En presencia de explosivos nitroaromáticos se produce una inhibición de la reacción escuaridinatiol y la suspensión permanece azul. Esta inhibición es debida a la formación de complejos de transferencia de carga entre las poliaminas y los explosivos nitroaromáticos. En la segunda parte de esta tesis doctoral se han preparado materiales híbridos con cavidades biomiméticas basados en el empleo de MCM-41 como soporte inorgánico mesoporoso (ver capítulo 4). Para ello se ha procedido al anclaje de tres fluoróforos (pireno, dansilo y fluoresceína) en el interior de los poros del soporte inorgánico y, posteriormente, se ha hidrofobado el interior de material mediante la reacción de los silanoles superficiales con 1,1,1,3,3,3-hexametildisilazano. Mediante este procedimiento se consiguen cavidades hidrófobas que tienen en su interior los fluoróforos. Estos materiales son fluorescentes cuando se suspenden en acetonitrilo mientras que cuando se añaden explosivos nitroaromáticos a estas suspensiones se observa una desactivación de la emisión muy marcada. Esta desactivación de la emisión es debida a la inclusión de los explosivos nitroaromáticos en la cavidad biomimética y a la interacción de estas moléculas (mediante interacciones de ¿- stacking) con el fluoróforo. Una característica importante de estos materiales híbridos sensores es que pueden ser reutilizados después de la extracción del explosivo de las cavidades hidrofóbicas. En la última parte de esta tesis doctoral se han desarrollado materiales híbridos orgánicoinorgánicos funcionalizados con ¿puertas moleculares¿ que han sido empleados también para detectar explosivos nitroaromáticos (ver capítulo 5). Para la preparación de estos materiales también se ha empleado MCM-41 como soporte inorgánico. En primer lugar, los poros del soporte inorgánico se cargan con un colorante/fluoróforo seleccionado. En una segunda etapa, la superficie externa del material cargado se ha funcionalizado con ciertas moléculas con carácter electrón dador (pireno y ciertos derivados del tetratiafulvaleno). Estas moléculas ricas en electrones forman una monocapa muy densa (debida a las interacciones dipolo-dipolo entre estas especies) alrededor de los poros que inhibe la liberación del colorante. En presencia de explosivos nitroaromáticos se produce la ruptura de la monocapa, debido a interacciones de ¿-stacking con las moléculas ricas en electrones, con la consecuencia de una liberación del colorante atrapado en el interior de los poros observándose una respuesta cromo-fluorogénica / Salinas Soler, Y. (2013). Functional hybrid materials for the optical recognition of nitroaromatic explosives involving supramolecular interactions [Tesis doctoral]. Editorial Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/31663 / TESIS / Premios Extraordinarios de tesis doctorales
244

Studium vlivu organických vláken na požární odolnost betonu / Study of the influence organic fibres on the fire resistance of concrete

Klobása, Jan January 2022 (has links)
The master thesis is focused on current issues of concrete behaviour under high temperatures. In the theoretical part, a search of knowledge about changes in concrete, which take place when exposed to thermal loads, which simulates the effect of fire, is performed, and summarized. It is also important to summarize the changes in the individual components that are used to produce concrete. This work describes the effect of high temperatures on mechanical and physical properties as well. There is an information about the most used fibres and their function in concrete. Emphasis is placed on describing the possibility of using recycled PET or cellulose fibres due to the positive environmental impact. In the experimental part, recipes with different types and amounts of fibres are proposed. The subject of the research was to determine how individual types and amounts of fibres affect the physical mechanical properties of concrete and their suitability for use at high temperatures. Microscopic scanning and study of changes in the structure of concrete was also performed.
245

VÝZKUM A VÝVOJ KOMPOZITNÍCH MATERIÁLŮ S VYŠŠÍ REZISTENCÍ VŮČI PŮSOBENÍ VYŠŠÍCH TEPLOT / RESEARCH AND DEVELOPMENT COMPOSITE MATERIAL WITH A HIGHER RESISTANCE TO HIGH TEMPERATURES

Válek, Jaroslav January 2014 (has links)
Concrete has many advantageous properties as regards resistance to fire. It is non-flammable and it has a low thermal conductivity. However, concrete structures, which are not designed for resistance against fire, show significant damage after heating. In particular, the explosive flaking with the consequence of weakening the reinforced concrete cross-section and exposing the steel reinforcement to the temperatures higher than critical temperature of reinforcement. There are only a few possible measures of preventing or mitigating the effects temperature load used. Ways of protection can be divided into two systems: active and passive. Active systems are designed to ensure the greatest possible reduction of temperatures the concrete is exposed to. Passive systems directly resist to high temperatures and fire. Design of composition of concrete with the aim of higher resistance to exposition to high temperatures belongs among the passive systems. A part of the work focuses on summary searches of the problems of concrete and reinforced concrete structures exposed to high temperatures and fire. The goal of the work is defining requirements for cement matrix based composite material and its design ensuring the highest possible resistance to high temperatures or direct fire.
246

Effects of high temperatures in the physical, mechanical, and drilling features of Prada limestone.

Martínez Ibáñez, Víctor 18 June 2023 (has links)
Tesis por compendio / [ES] Esta investigación se centra en la caliza de Prada, una formación del Cretácico inferior ubicada en la zona sur pirenaica de Cataluña (España). Se tomaron muestras de roca de sondeos perforados durante la etapa de diseño del túnel de Tres Ponts. El trabajo aquí presentado explora diferentes aspectos relacionados con el comportamiento térmi-co de la caliza de Prada y las consecuencias derivadas en el túnel de Tres Ponts. En primer lugar, este trabajo describe la variación en las propiedades texturales, físicas y mecánicas de la caliza de Prada después de ser sometida a temperaturas de entre 105 y 600 ºC, y luego enfriada a un ritmo lento o mediante templado, y determina las tem-peraturas clave y los métodos de enfriamiento que afectan más la estabilidad en caso de incendio en el túnel de Tres Ponts. En segundo lugar, esta investigación se centra en las causas y mecanismos implicados en el comportamiento explosivo y la liberación de gas sulfuroso observado en una fracción gris oscuro de muestras de caliza de Prada. Las implicaciones de tales muestras de color gris oscuro son críticas en infraestructuras subterráneas y en minería, ya que el potencial explosivo de esas muestras conlleva el riesgo de fracturación masiva y de disminución brusca en la resistencia. Además, el gas sulfuroso liberado tiene efectos nocivos sobre la salud de las personas y el poten-cial de formar compuestos ácidos que corroen los materiales, acortando su durabilidad y aumentando los costes de mantenimiento. Posteriormente, este trabajo determina si el tratamiento térmico sobre la caliza de Prada tiene un efecto significativo en facilitar su perforabilidad. Comprender la variación en el rendimiento de perforación de la caliza de Prada tratada térmicamente ayudaría a mejorar la eficiencia de los medios mecánicos de excavación. Finalmente, se proponen algunas correlaciones para deter-minar indirectamente las características de resistencia, deformación y perforabilidad de la caliza de Prada tras ser tratada térmicamente, a partir de pruebas simples, rápidas y no destructivas. / [CA] Aquesta investigació es centra en la calcària de Prada, una formació del Cretaci inferior situada a la zona sud pirinenca de Catalunya (Espanya). Es van prendre mostres de roca de sondejos perforats durant l'etapa de disseny del túnel de Tres Ponts. El treball aquí presentat explora diferents aspectes relacionats amb el comportament tèrmic de la calcària de Prada i les conseqüències derivades al túnel de Tres Ponts. En primer lloc, aquest treball descriu la variació en les propietats texturals, físiques i mecàniques de la calcària de Prada després de ser tractada a temperatures d'entre 105 i 600 ºC, i després refredada a un ritme lent o ràpid, i determina les temperatures clau i els mètodes de refredament que afecten més l'estabilitat en cas d'incendi al túnel de Tres Ponts. En segon lloc, aquesta investigació es centra en les causes i mecanismes implicats en el comportament explosiu i l'alliberament de gas sulfurós observat en una fracció gris fosc de mostres de calcària de Prada. Les implicacions de tals mostres de color gris fosc són crítiques en infraestructures subterrànies i en mineria, ja que el potencial explosiu d'aquestes mostres comporta el risc de fracturació massiva i de disminució brusca en la resistència. A més, el gas sulfurós alliberat té efectes nocius sobre la salut de les persones i el potencial de formar compostos àcids que corroeixen els materials, retallant la seua durabilitat i augmentant els costos de manteniment. Posteriorment, aquest treball determina si el tractament tèrmic sobre la calcària de Prada té un efecte significatiu en facilitar la seua perforabilitat. Comprendre la variació en el rendiment de perforació de la calcària de Prada tractada tèrmicament ajudaria a millorar l'eficièn-cia dels mitjans mecànics d'excavació. Finalment, es proposen algunes correlacions per determinar indirectament les característiques de resistència, deformació i perforabilitat de la calcària de Prada després de ser tractada tèrmicament, a partir de proves simples, ràpides i no destructives. / [EN] This research is focused on Prada limestone, a lower Cretaceous formation located in the Catalan south Pyrenean zone (Spain). Rock samples were taken from boreholes drilled during the design stage of the Tres Ponts Tunnel. The work presented here explores different aspects related to the thermal behaviour of Prada limestone and the derived consequences on the Tres Ponts Tunnel. Firstly, this work reports the variation in the textural, physical, and mechanical properties of Prada limestone after being heated at temperatures of between 105 and 600 ºC and then cooled at a slow rate or by quenching and determines key temperatures and cooling methods that would most affect stability in case of a fire in the Tres Ponts Tunnel. Secondly, this research fo-cuses on the causes and mechanisms involved in the explosive behaviour and release of sulphurous gas observed on a dark grey fraction of samples from Prada limestone. Implications of such dark grey samples are critical in underground infrastructure and mining engineering works, as the explosive potential of that sample represents risk of mass fracturing and dramatic strength decay. Moreover, the sulphurous gas released has harmful health effects and may form acid compounds that corrode materials, shorten their durability, and increase maintenance costs. Later, this work determines if thermal treatment on Prada limestone has a significant effect on improving its drilla-bility. Understanding the variation in the drilling performance of the thermally treated Prada limestone would help improve the efficiency of mechanical excavation means. Finally, some correlations are proposed to indirectly determine the strength, deformational, and drillability features of Prada limestone after being thermally treated from simple, quick and non-destructive tests. / This research was partially supported by the Spanish Government [grant number RTI2018-099052-B-I00], also the Vice-Rectorate of Research and Knowledge Transfer at the University of Alicante through projects UAUSTI19-25 and UAUSTI20-20, and by the Departamento de Ingeniería del Terreno at the Universitat Politècnica de València. / Martínez Ibáñez, V. (2021). Effects of high temperatures in the physical, mechanical, and drilling features of Prada limestone [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/171023 / Compendio
247

Contributions aux équations d'évolution frac-différentielles / Contributions to frac-differential evolution equations

Lassoued, Rafika 08 January 2016 (has links)
Dans cette thèse, nous nous sommes intéressés aux équations différentielles fractionnaires. Nous avons commencé par l'étude d'une équation différentielle fractionnaire en temps. Ensuite, nous avons étudié trois systèmes fractionnaires non linéaires ; le premier avec un Laplacien fractionnaire et les autres avec une dérivée fractionnaire en temps définie au sens de Caputo. Dans le premier chapitre, nous avons établi les propriétés qualitatives de la solution d'une équation différentielle fractionnaire en temps qui modélise l'évolution d'une certaine espèce. Plus précisément, l'existence et l'unicité de la solution globale sont démontrées pour certaines valeurs de la condition initiale. Dans ce cas, nous avons obtenu le comportement asymptotique de la solution en t^α. Sous une autre condition sur la donnée initiale, la solution explose en temps fini. Le profil de la solution et l'estimation du temps d'explosion sont établis et une confirmation numérique de ces résultats est présentée. Les chapitres 4, 5 et 6 sont consacrés à l'étude théorique de trois systèmes fractionnaires : un système de la diffusion anormale qui décrit la propagation d'une épidémie infectieuse de type SIR dans une population confinée, le Brusselator avec une dérivée fractionnaire en temps et un système fractionnaire en temps avec une loi de balance. Pour chaque système, on présente l'existence globale et le comportement asymptotique des solutions. L'existence et l'unicité de la solution locale pour les trois systèmes sont obtenues par le théorème de point fixe de Banach. Cependant, le comportement asymptotique est établi par des techniques différentes : le comportement asymptotique de la solution du premier système est démontré en se basant sur les estimations du semi-groupe et le théorème d'injection de Sobolev. Concernant le Brusselator fractionnaire, la technique utilisée s'appuie sur un argument de feedback. Finalement, un résultat de régularité maximale est utilisé pour l'étude du dernier système. / In this thesis, we are interested in fractional differential equations. We begin by studying a time fractional differential equation. Then we study three fractional nonlinear systems ; the first system contains a fractional Laplacian, while the others contain a time fractional derivative in the sense of Caputo. In the second chapter, we establish the qualitative properties of the solution of a time fractional equation which describes the evolution of certain species. The existence and uniqueness of the global solution are proved for certain values of the initial condition. In this case, the asymptotic behavior of the solution is dominated by t^α. Under another condition, the solution blows-up in a finite time. The solution profile and the blow-up time estimate are established and a numerical confirmation of these results is presented. The chapters 4, 5 and 6 are dedicated to the study of three fractional systems : an anomalous diffusion system which describes the propagation of an infectious disease in a confined population with a SIR type, the time fractional Brusselator and a time fractional reaction-diffusion system with a balance law. The study includes the global existence and the asymptotic behavior. The existence and uniqueness of the local solution for the three systems are obtained by the Banach fixed point theorem. However, the asymptotic behavior is investigated by different techniques. For the first system our results are proved using semi-group estimates and the Sobolev embedding theorem. Concerned the time fractional Brusselator, the used technique is based on an argument of feedback. Finally, a maximal regularity result is used for the last system.
248

Акутни ефекти различитих садржаја уводно-припремног дела тренинга на моторичке способности и неуромишићну адаптацију кошаркаша / Akutni efekti različitih sadržaja uvodno-pripremnog dela treninga na motoričke sposobnosti i neuromišićnu adaptaciju košarkaša / Acute Effects of Different Types of Warm-up and Stretching on Motor Abilities and Neuromuscular Adaptation of Basketball Players

Stevanović Vuk 06 September 2016 (has links)
<p>Циљ рада: Циљ истраживања је да се утврди разлика у акутним ефектима статичког (СИ) и динамичког истезања (ДИ), у комбинацији са специфичним кошаркашким загревањем (СКЗ), на флексибилност, експлозивну снагу ногу, брзину, агилност и неуромишићну адаптацију кошаркаша јуниорског узраста.</p><p>Методе: Истраживање у оквиру ове докторске тезе су чинила два одвојена експеримента, један спроведен у теренским условима, и други спроведен у лабораторијским. Оба су била &bdquo;cross-over&ldquo; дизајна. У теренском експерименту је учествовало 46 кошаркаша (узраста 17&plusmn;0,83 година), док је у лабораторијском учествовало 12 (узраста 17,7&plusmn;0,49 година). У теренском експерименту су тестиране четири моторичке способности. За процену флексибилности коришћен је тест досезања у седећем претклону, експлозивна снага ногу је процењивана уз помоћ вертикалног скока са контактне плоче, брзина трчањем на 20 метара, док је Т тест коришћен за процену агилности. У лабораторијском експерименту је као мера неурофизиолошке адаптације коришћена промена ексцитабилности &alpha;-мотонеурона, која је представљена као однос Хофмановог (Х) рефлекса и М таласа (Х/М). За њихово одређивање се користио Medelec ST-10 стимулатор (Medelec, Old Woking, UK). Површинске електромиографске електроде су биле постављене на унутрашњој глави m.gastrocnemius-a одскочне ноге, применом тзв. &bdquo;belly-tendon&ldquo; монтаже. Као третмани, у оба експеримента су коришћени протокол статичког и протокол динамичког истезања, уз комбинацију са специфичним кошаркашким загревањем. Мерења су се у оба експеримента изводила у 3 временске тачке и то пре протокола истезања, одмах након протокола истезања (а пре специфичног кошаркашког загревања) и одмах након специфичног кошаркашког загревања.</p><p>Резултати: Резултати истраживања показују да постоје одређене разлике акутних ефеката комбинација протокола СИ+СКЗ и ДИ+СКЗ. Комбинација протокола СИ+СКЗ је повољније утицала на експлозивну снагу ногу и на агилност кошаркаша јуниорског узраста. Ефекти обе комбинације протокола су били готово идентични на флексибилност, а разлика је изостала и у ефектима на брзину, иако је пре СКЗ био&nbsp;уочљив негативан ефекат СИ. Однос Х/М се значајно разликовао одмах након истезања, када је СИ значајно оборило однос, али су се те разлике изгубиле након примене СКЗ.</p><p>Закључак: Посматрајући ефекте комбинације протокола СИ+СКЗ и ДИ+СКЗ на моторичке способности и неуромишићну адаптацију кошаркаша јуниорског узраста, може се закључити да је примена СИ+СКЗ препоручљивија у свакодневном тренингу и такмичењу.</p> / <p>Cilj rada: Cilj istraživanja je da se utvrdi razlika u akutnim efektima statičkog (SI) i dinamičkog istezanja (DI), u kombinaciji sa specifičnim košarkaškim zagrevanjem (SKZ), na fleksibilnost, eksplozivnu snagu nogu, brzinu, agilnost i neuromišićnu adaptaciju košarkaša juniorskog uzrasta.</p><p>Metode: Istraživanje u okviru ove doktorske teze su činila dva odvojena eksperimenta, jedan sproveden u terenskim uslovima, i drugi sproveden u laboratorijskim. Oba su bila &bdquo;cross-over&ldquo; dizajna. U terenskom eksperimentu je učestvovalo 46 košarkaša (uzrasta 17&plusmn;0,83 godina), dok je u laboratorijskom učestvovalo 12 (uzrasta 17,7&plusmn;0,49 godina). U terenskom eksperimentu su testirane četiri motoričke sposobnosti. Za procenu fleksibilnosti korišćen je test dosezanja u sedećem pretklonu, eksplozivna snaga nogu je procenjivana uz pomoć vertikalnog skoka sa kontaktne ploče, brzina trčanjem na 20 metara, dok je T test korišćen za procenu agilnosti. U laboratorijskom eksperimentu je kao mera neurofiziološke adaptacije korišćena promena ekscitabilnosti &alpha;-motoneurona, koja je predstavljena kao odnos Hofmanovog (H) refleksa i M talasa (H/M). Za njihovo određivanje se koristio Medelec ST-10 stimulator (Medelec, Old Woking, UK). Površinske elektromiografske elektrode su bile postavljene na unutrašnjoj glavi m.gastrocnemius-a odskočne noge, primenom tzv. &bdquo;belly-tendon&ldquo; montaže. Kao tretmani, u oba eksperimenta su korišćeni protokol statičkog i protokol dinamičkog istezanja, uz kombinaciju sa specifičnim košarkaškim zagrevanjem. Merenja su se u oba eksperimenta izvodila u 3 vremenske tačke i to pre protokola istezanja, odmah nakon protokola istezanja (a pre specifičnog košarkaškog zagrevanja) i odmah nakon specifičnog košarkaškog zagrevanja.</p><p>Rezultati: Rezultati istraživanja pokazuju da postoje određene razlike akutnih efekata kombinacija protokola SI+SKZ i DI+SKZ. Kombinacija protokola SI+SKZ je povoljnije uticala na eksplozivnu snagu nogu i na agilnost košarkaša juniorskog uzrasta. Efekti obe kombinacije protokola su bili gotovo identični na fleksibilnost, a razlika je izostala i u efektima na brzinu, iako je pre SKZ bio&nbsp;uočljiv negativan efekat SI. Odnos H/M se značajno razlikovao odmah nakon istezanja, kada je SI značajno oborilo odnos, ali su se te razlike izgubile nakon primene SKZ.</p><p>Zaključak: Posmatrajući efekte kombinacije protokola SI+SKZ i DI+SKZ na motoričke sposobnosti i neuromišićnu adaptaciju košarkaša juniorskog uzrasta, može se zaključiti da je primena SI+SKZ preporučljivija u svakodnevnom treningu i takmičenju.</p> / <p>Objective: The aim of this study was to determine the difference of acute effects of static stretching (SS) and dynamic stretching (DS), in combination with specific basketball warm-up (SBWU), on flexibility, explosive leg strength, speed, agility and neuromuscular adaptation of basketball players U18.</p><p>Methods: This study consisted of two separated experiments, first in field conditions, and second conducted in laboratory. Both had &bdquo;cross-over&ldquo; design. Forty-six basketball players (age: 17&plusmn;0,83 years) participated in field experiment, while twelve participated in laboratory experiment (age 17,7&plusmn;0,49 years). In field experiment, four motor abilities were tested. Seat and rech test was used for the evaluation of flexibility, explosive leg strength was evaluated by vertical jump from contact plate, speed by 20m run, and T test was used for agility testing. In laboratory experiment, the excitability of &alpha;-motoneuron was taken for the evaluation of neuromuscular adaptation. It is presented as a ratio of the maximal amplitudes of Hoffman (H) reflex and M wave (H/M). For their determining we used Medelec ST-10 stimulator (Medelec, Old Woking, UK). Surface electromyographic (EMG) electrodes were placed over the m.gastrocnemius medialis, and Achilles tendon, in a &bdquo;belly-tendon&ldquo; montage. In both experiments, SS protocol and DS protocol, in the combination with SBWU, were used as a treatment. Measures were taken in 3 time points: before the stretching, immediately after stretching (and before SBWU) and immediately after the SBWU.</p><p>Results: Results of this study showed that there are certain differences in acute effects of combination of protocols SS+SBWU and DS+SBWU. Combination of protocols SS+SBWU had more positive influence on explosive leg strength and agility of U18 basketball players. The effects of both protocols were almost the same on flexibility, and there was no noticeable difference in effects on speed, although before SBWU there was significant negative of SS. Immediately after the stretching there was significant difference in H/M ratio, it was significantly lower after the SS, but after the application of SBWU, differences disappeared.<br />&nbsp;<br />Conlcusion: Regarding the effects of SS+SBWU and DS+SBWU protocols on motor abilities and neuromuscular adaptation of U18 basketball players, it could be concluded that the use of SS+SBWU is more preferrable in everyday practice and competition.</p>
249

Etude de la réaction 18F(p,alpha)15O par réction de transfert pour application à l'émission gamma des novae

de Séréville, Nicolas 11 December 2003 (has links) (PDF)
L'émission gamma des novae à, et en dessous, de 511 keV provient essentiellement de l'annihilation des positrons venant de la décroissance beta+ du 18F. L'interprétation de cette émission, à l'aide d'observations par le satellite INTEGRAL par exemple, nécessite une bonne connaissance de la nucléosynthèse du 18F. Dans ce contexte, le taux de la réaction 18F(p,alpha)15O est le moins bien connu à cause de deux résonances correspondant aux niveaux excités Ex = 6.419 et 6.449 MeV dans le 19Ne dont les largeurs protons sont totalement inconnues. Nous avons déterminé ces largeurs protons par le biais d'une réaction de transfert d'un nucléon D(18F,p alpha)15N peuplant les niveaux analogues, dans le 19F, des niveaux d'intérêt astrophysique. Nous avons utilisé un faisceau radioactif de 18F accéléré à 14 MeV au Centre de Recherche du Cyclotron de Louvain--la--Neuve sur une cible de CD2 en cinématique inverse ainsi que le détecteur multi--piste au silicium LEDA. Une analyse en DWBA a permi de déterminer la largeur proton de ces deux résonances et a montré qu'elles ne pouvaient pas être négligées dans le calcul du taux de réaction. Une étude détaillée des incertitudes restantes sur le taux de réaction a été entreprise et particulièrement en ce qui concerne les interférences entre ces résonances et une autre résonance à plus haute énergie dans le 19Ne. Le taux de réaction ainsi établi diffère peu de l'ancien taux nominal mais repose maintenant sur des bases plus solides permettant une meilleure interprétation des futures observations gamma des novae et donc une meilleure contrainte des modèles astrophysiques.
250

Numerical Simulation of Blast Interaction with the Human Body: Primary Blast Brain Injury Prediction

Haladuick, Tyler January 2014 (has links)
In Operations Enduring Freedom and Iraqi Freedom, explosions accounted for 81% of all injuries; this is a higher casualty percentage than in any previous wars. Blast wave overpressure has recently been associated with varying levels of traumatic brain injury in soldiers exposed to blast loading. Presently, the injury mechanism behind primary blast brain injury is not well understood due to the complex interactions between the blast wave and the human body. Despite these limitations in the understanding of head injury thresholds, head kinematics are often used to predict the overall potential for head injury. The purpose of this study was to investigate head kinematics, and predict injury from a range of simulated blast loads at varying standoff distances and differing heights of bursts. The validated Generator of body data multi-body human surrogate model allows for numerical kinematic data simulation in explicit finite element method fluid structure interaction blast modeling. Two finite element methods were investigated to simulate blast interaction with humans, an enhanced blast uncoupled method, and an Arbitrary Lagrangian Eularian fully coupled method. The enhanced blast method defines an air blast function through the application of a blast pressure wave, including ground reflections, based on the explosives relative location to a target; the pressures curves are based on the Convention Weapons databases. LBE model is efficient for parametric numerical studies of blast interaction where the target response is the only necessary result. The ALE model, unlike classical Lagrangian methods, has a fixed finite element mesh that allows material to flow through it; this enables simulation of large deformation problems such as blast in an air medium and its subsequent interaction with structures. The ALE model should be used when research into a specific blast scenario is of interest, since this method is more computationally expensive. The ALE method can evaluate a blast scenario in more detail including: explosive detonation, blast wave development and propagation, near-field fireball effects, blast wave reflection, as well as 3D blast wave interaction, reflection and refraction with a target. Both approaches were validated against experimental blast tests performed by Defense Research and Development Valcartier and ConWep databases for peak pressure, arrival time, impulse, and curve shape. The models were in good agreement with one another and follow the experimental data trend showing an exponential reduction in peak acceleration with increasing standoff distance until the Mach stem effect reached head height. The Mach stem phenomenon is a shock front formed by the merging of the incident and reflected shock waves; it increases the applied peak pressure and duration of a blast wave thus expanding the potential head injury zone surrounding a raised explosive. The enhanced blast model was in good agreement with experimental data in the near-field, and mid-field; however, overestimated the peak acceleration, and head injury criteria values in the far-field due to an over predicted pressure impulse force. The ALE model also over predicted the response based on the head injury criteria at an increased standoff distance due to smearing of the blast wave over several finite elements leading to an increased duration loading. According to the Abbreviated Injury Scale, the models predicted a maximal level 6 injury for all explosive sizes in the near-field, with a rapid acceleration of the head over approximately 1 ms. There is a drastic exponential reduction in the insult force and potential injury received with increasing standoff distance outside of the near-field region of an explosive charge.

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