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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.
201

Measuring the electric field of picosecond to nanosecond pulses with high spectral resolution and high temporal resolution

Cohen, Jacob Arthur 08 October 2010 (has links)
We demonstrate four experimentally simple methods for measuring very complex ultrashort light pulses. Although each method is comprised of only a few optical elements, they permit the measurement of extremely complex pulses with time-bandwidth products greater than 65,000. First, we demonstrate an extremely simple frequency-resolved-optical gating (GRENOUILLE) device for measuring the intensity and phase of pulses up to ~20ps in length. In order to achieve the required high spectral resolution and large temporal range, it uses a few-cm-thick second harmonic-generation crystal in the shape of a pentagon. This has the additional advantage of reducing the device's total number of components to three. Secondly, we introduce a variation of spectral interferometry (SI) using a virtually imaged phased array and grating spectrometer for measuring long complex ultrashort pulses up to 80 ps in length. Next, we introduce a SI technique for measuring the complete intensity and phase of relatively long and very complex ultrashort pulses. It involves making multiple measurements using SI (in its SEA TADPOLE variation) at numerous delays, measuring many temporal pulselets within the pulse, and concatenating the resulting pulselets. Its spectral resolution is the inverse delay range--many times higher than that of the spectrometer used. The waveforms were measured with ~ fs temporal resolution over a temporal range of ~ns and had time-bandwidth products exceeding 65,000, which to our knowledge is the largest time-bandwidth product ever measured with ~fs temporal resolution. Finally, we demonstrate a single-shot measurement technique that temporally interleaves hundreds of measurements with ~fs temporal resolution. It is another variation of SI for measuring the complete intensity and phase of relatively long and complex ultrashort pulses in a single shot. It uses a grating to introduce a transverse time delay into a reference pulse which gates the unknown pulse by interfering it at the image plane of an imaging spectrometer. It provided ~125 fs temporal resolution and a temporal range of 70 ps using a low-resolution spectrometer.
202

Measurement of the beta-neutrino correlation in laser trapped {sup 21}Na

Scielzo, Nicholas David January 2003 (has links)
Thesis (Ph.D.); Submitted to Univ. of California, Berkeley, CA (US); 1 Jun 2003. / Published through the Information Bridge: DOE Scientific and Technical Information. "LBNL--54350" Scielzo, Nicholas David. USDOE Director. Office of Science. Nuclear Physics (US) 06/01/2003. Report is also available in paper and microfiche from NTIS.
203

Electromagnetic Wave Propagation in Two-Dimensional Photonic Crystals

Stavroula Foteinopoulou January 2003 (has links)
Thesis (Ph.D.); Submitted to Iowa State Univ., Ames, IA (US); 12 Dec 2003. / Published through the Information Bridge: DOE Scientific and Technical Information. "IS-T 2048" Stavroula Foteinopoulou. 12/12/2003. Report is also available in paper and microfiche from NTIS.
204

Ion Acceleration from the Interaction of Ultra-Intense Lasers with Solid Foils

Allen, M January 2004 (has links)
Thesis (Ph.D.); Submitted to the Univ. of California, Berkeley, CA (US); 24 Nov 2004. / Published through the Information Bridge: DOE Scientific and Technical Information. "UCRL-TH-208645" Allen, M. 11/24/2004. Report is also available in paper and microfiche from NTIS.
205

Modélisation physique et numérique par la méthode des éléments finis de frontière de la distribution du potentiel et du champ électrique le long d'un isolateur standard de poste 735 KV recouvert de glace /

Volat, Christophe, January 2002 (has links)
Thèse (D.Eng.)-- Université du Québec à Chicoutimi, 2002. / Document électronique également accessible en format PDF. CaQCU
206

Correção fenotípica do nanismo avaliada por diferentes parâmetros de crescimento após administração de DNA plasmidial em modelo animal de deficiência isolada do hormônio do crescimento / Phenotypic correction of dwarfism mediated by different growth parameters after plasmid DNA administration in an animal model of isolated growth hormone deficiency

HIGUTI, ELIZA 22 June 2016 (has links)
Submitted by Claudinei Pracidelli (cpracide@ipen.br) on 2016-06-22T11:39:54Z No. of bitstreams: 0 / Made available in DSpace on 2016-06-22T11:39:54Z (GMT). No. of bitstreams: 0 / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / Tese (Doutorado em Tecnologia Nuclear) / IPEN/T / Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP / FAPESP:11/21708-6
207

Correção fenotípica do nanismo avaliada por diferentes parâmetros de crescimento após administração de DNA plasmidial em modelo animal de deficiência isolada do hormônio do crescimento / Phenotypic correction of dwarfism mediated by different growth parameters after plasmid DNA administration in an animal model of isolated growth hormone deficiency

HIGUTI, ELIZA 22 June 2016 (has links)
Submitted by Claudinei Pracidelli (cpracide@ipen.br) on 2016-06-22T11:39:54Z No. of bitstreams: 0 / Made available in DSpace on 2016-06-22T11:39:54Z (GMT). No. of bitstreams: 0 / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / A deficiência de hormônio de crescimento (DGH) é a deficiência mais comum entre os hormônios pituitários. A terapia utilizada atualmente consiste de injeções diárias de hormônio de crescimento humano recombinante (r-hGH), entretanto esta terapia apresenta alguns inconvenientes, como a necessidade de frequentes injeções de r-hGH durante um longo período de vida, dependendo da severidade da deficiência, e o alto custo do hormônio, em razão dos dispendiosos processos de purificação. Uma alternativa ao tratamento padrão seria aquele no qual fossem evitados estes tipos de inconvenientes e o processo de liberação da proteína fosse sustentável, por um longo período e promovesse níveis normais e sustentáveis do fator de crescimento semelhante à insulina I (IGF-I), o principal mediador dos efeitos do GH. Uma alternativa é a terapia gênica in vivo, baseada na administração de DNA plasmidial em diversos órgãos/tecidos, seguida de eletroporação. É considerada uma metodologia bastante promissora e que tem sido alvo de vários estudos para diversos tipos de deficiências sistêmicas. Neste trabalho foram realizadas diversas administrações de um plasmídeo contendo o gene do hormônio de crescimento humano, nos músculos quadríceps exposto ou tibial anterior sem exposição, seguidas de eletroporação, em camundongos anões e imunodeficientes (lit/scid) com 40-80 dias de idade, na tentativa de obter uma correção fenotípica do nanismo, mediante a avaliação de parâmetros de crescimento. A administração deste plasmídeo no músculo tibial anterior, em camundongos com a idade inicial de 40 dias, foi capaz de proporcionar uma normalização dos níveis de mIGF-I, quando comparados aos dos camundongos não-deficientes de GH. Além disso, foram obtidos valores de catch-up dos parâmetros de crescimento longitudinal de 36-77%. Visando uma maior eficiência na expressão de GH, foram construídos plasmídeos parentais, e a partir destes, foram produzidos minicírculos de DNA com os promotores do CMV e Ubiquitina C e com os cDNAs de hGH e mGH. Estes minicírculos de DNA foram transfectados em células HEK 293 e foram até 2 vezes mais eficientes em relação aos plasmídeos convencionais com o promotor do CMV. Estes dados são bastantes promissores e abrem caminho para ensaios mais eficientes, utilizando este tipo de protocolo de terapia gênica para a DGH, visando uma normalização de todos os parâmetros de crescimento. / Tese (Doutorado em Tecnologia Nuclear) / IPEN/T / Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP / FAPESP:11/21708-6
208

Aplicação de campos elétricos em procedimentos de extração em fase sólida. / Application of electric fields in solid phase extraction procedures

Orlando, Ricardo Mathias 06 March 2011 (has links)
Orientadores: Susanne Rath, Jarbas José Rodrigues Rohwedder / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Química / Made available in DSpace on 2018-08-19T11:12:21Z (GMT). No. of bitstreams: 1 Orlando_RicardoMathias_D.pdf: 5151319 bytes, checksum: 53a60cd9c94d86b8a9e269a87ef0c9ac (MD5) Previous issue date: 2011 / Resumo: O preparo de amostra representa uma etapa determinante e crítica no processo de análise e a extração em fase sólida (SPE) é uma técnica amplamente empregada no preparo de matrizes complexas. O objetivo deste trabalho foi o desenvolvimento de dispositivos e procedimentos que permitem aplicar campos elétricos em SPE empregando cartuchos (E-SPE®), visando adicionar os mecanismos da eletroforese ao processo cromatográfico. Para tanto, foram desenvolvidos eletrodos e cartuchos que possibilitam a aplicação de campos elétricos, além de um sistema para monitorar e controlar parâmetros eletrocromatográficos tais como: vazão, corrente elétrica, potencial elétrico e temperatura. Com esses dispositivos foram realizadas extrações com aplicação de campo elétrico empregando compostos modelo aniônicos, catiônicos e anfotéricos. Para permitir uma melhor compreensão dos fenômenos envolvidos foram avaliados diversos parâmetros de extração, entre esses: concentração de íons em solução, pH, modificador orgânico, volume de solução de lavagem e tipo de sorvente. O sistema foi avaliado também na determinação de antimicrobianos em leite. Dependendo da polaridade empregada sobre os eletrodos, a aplicação do campo elétrico foi capaz de modular (acelerar ou retardar) a saída dos compostos modelo do cartucho. Os resultados de extração obtidos demonstraram a eficácia dos dispositivos desenvolvidos, além da grande potencialidade do uso de campos elétricos em SPE para obter maiores recuperações dos analitos de interesse e/ou remoção de interferentes / Abstract: Sample preparation is a crucial and determinant step for the analysis process and solid phase extraction (SPE) is a widely used technique in the preparation of complex matrices. The aim of this work was the development of devices and procedures for applying electric fields to SPE cartridges (SPE-E ®), in order to add the mechanisms of electrophoresis to the chromatographic process. For this purpose, electrodes and cartridges that allow the application of electric fields were developed, besides a system to monitor and control electrochromatographic parameters such as: flow, electric current, electric potential and temperature. By means of these devices, extractions with application of electric fields were performed using anionic, cationic and amphoteric model compounds. In order to allow a better understanding of the phenomena involved several extraction parameters were evaluated, among these: the concentration of ions in solution, pH, organic modifier, volume of washing solution and type of sorbent. The system was also evaluated for the determination of antibiotics in milk. Depending on the polarity of the electrodes used, the application of an electric field was able to modulate (accelerate or retard) the output of the model compounds from the cartridge. The extraction results obtained showed the effectiveness of the devices developed, and the immense potential of the use of electric fields in SPE to obtain better recoveries of the analytes and/or for removing interferents / Doutorado / Quimica Analitica / Doutor em Ciências
209

Determination of the signaling pathways and subcellular targets in response to nanosecond pulsed electric fields / Détermination des cascades de signalisation et des cibles subcellulaires en réponse à des impulsions de champs électriques nanosecondes

Carr, Lynn 15 December 2016 (has links)
Les impulsions de champ électrique nanoseconde de forte intensité (nsPEF) ont été proposées pour le traitement du cancer avec des effets secondaires minimes et peu susceptibles de conduire à une résistance de la tumeur au traitement. Le glioblastome multiforme (GBM) est un cancer du cerveau incurable montrant une résistance aux traitements actuels tels que la chirurgie, la radiothérapie et la chimiothérapie. Dans cette thèse, l'imagerie des cellules vivantes est utilisée pour étudier in vitro les effets de nsPEF sur une lignée de cellules de glioblastome humain (U87-MG), et pour évaluer la pertinence de l'utilisation des nsPEF en tant que nouveau traitement pour le GBM. En accord avec les résultats publiés précédemment, nous montrons que les cellules U87-MG répondent aux nsPEF avec une poration de la membrane plasmique, une augmentation rapide du calcium intracellulaire et une perte progressive du potentiel de membrane mitochondriale. De nouveaux résultats montrent que 100 impulsions de 10 ns délivrées à 44 kV/cm perturbent la dynamique de croissance des microtubules indépendamment du calcium et du gonflement, ces derniers étant connus pour provoquer la dépolymérisation des microtubules. La microscopie à super-résolution nous a permis de visualiser les flexions et ruptures de microtubules après l'application nsPEF suggérant un effet plus direct des impulsions. L'étude des nsPEF sur le calcium a également été menée via des indicateurs de calcium génétiquement encodés (GECIs) qui permettent une comparaison entre les GECIs et les indicateurs chimiques couramment utilisés. En utilisant le GECI GCaMP, le potentiel d'expression des GECIs dans des endroits subcellulaires spécifiques a permis de mettre en évidence une onde de calcium induite par l'application des nsPEF, grâce à une forme de GCaMP fixée à la membrane plasmatique. Ce phénomène, qui n'est pas habituel avec des indicateurs chimiques cytosoliques classiques en raison de la diffusion, permet de confirmer l'origine extracellulaire des pics de calcium post nsPEF. Cette thèse démontre que les nsPEF appliqués à des cellules U87-MG induisent plusieurs effets cellulaires majeurs et potentiellement destructeurs. La perturbation du réseau de microtubules par les nsPEF pourrait éventuellement être exploitée comme un antimitotique, administré localement, pour le traitement de GBM, avec des effets secondaires systémiques réduits et une faible résistance au traitement. / High powered, nanosecond duration pulsed electric fields (nsPEF) have been proposed as a minimal side-effect, electrical cancer therapy that is unlikely to result in tumour resistance. Glioblastoma multiforme (GBM) is an incurable brain cancer showing resistance to current treatments such as surgery, radiotherapy and chemotherapy. This thesis uses live-cell imaging to look in vitro at the effects of nsPEF on a human glioblastoma cell line (U87-MG) in a first step towards assessing its suitability as a novel treatment for GBM. In agreement with previously published results we show that U87-MG cells respond to nsPEF with plasma membrane poration, a rapid increase in intracellular calcium and a gradual loss of mitochondrial membrane potential. We present novel results showing that 100, 10 ns pulses delivered at 44 kV/cm disrupt microtubule growth dynamics in a way that is independent of calcium and swelling, both of which are known to cause microtubule depolymerisation. Super-resolution microscopy allowed us to visualise microtubules bending and breaking following nsPEF application suggesting a more direct effect of the pulse. We look also at the application of genetically encoded calcium indicators (GECIs) to nsPEF calcium studies making a comparison between GECIs and commonly used chemical indicators. Using the GECI GCaMP, we show the advantages of being able to express GECIs in specific subcellular locations by visualising an nsPEF induced calcium wave with a plasma membrane bound form of GCaMP. This event, which is not evident with classic cytosolic chemical indicators due to diffusion, helps confirm the extracellular origin of the post-nsPEF calcium spike. The work in this thesis demonstrates that nsPEF causes several major, and possibly destructive, cellular events when applied to U87-MG cells. The disruption of the microtubule network by nsPEF could potentially be exploited as a locally administered antimitotic, for GBM treatment, with reduced systemic side effects and lower occurrences of resistance.
210

Application des électrotechnologies pour une valorisation optimisée de la betterave à sucre dans un concept de bioraffinerie / Application of electrotechnologies for an optimized valorization of sugar beet in biorefinery concept

Almohammed, Fouad 24 January 2017 (has links)
Ce travail de thèse concerne l’utilisation des électrotechnologies pour une valorisation optimisée de la betterave à sucre conformément au concept de bioraffinerie. Les électro-technologies appliquées sont les champs électriques pulsés (CEP) et les décharges électriques de haute tension (DEHT). L’étude s’attache d’une part à l’optimisation d’un procédé alternatif pour l’extraction du sucre par pressage alcalin à froid assisté par CEP. D’autre part, elle propose des nouvelles voies pour la valorisation de deux coproduits de l’industrie betteravière qui sont les radicelles et la pulpe de betterave. Dans la première partie, le traitement électrique par CEP couplé au chaulage permet une meilleure désintégration du tissu betteravier. Il permet d’accélérer les cinétiques du pressage, d’améliorer le rendement ainsi que la qualité du jus et d’alléger la procédure de purification en aval de l’extraction. Une étude paramétrique d’optimisation a permis d’identifier le meilleur itinéraire d’application de ce nouveau procédé d’extraction. Les cossettes fraîches de betterave sont prétraitées par CEP à 600 V/cm pour 10 ms (Q = 2,7 Wh/kg). Les cossettes électroporées sont ensuite pressées à froid pour extraire 75 % du jus. Les cossettes pressées subissent un pressage alcalin avec 10 % du lait de chaux. Afin d’extraire le sucre résiduel dans le gâteau de pressage obtenu, deux étapes de pressage supplémentaires avec une étape intermédiaire d’hydratation sont nécessaires. Ce procédé optimisé permet de bien épuiser les cossettes en sucre (perte en sucre de 0,23 % et matière sèche de pulpes de 39 %) pendant une courte durée d’extraction (30 min) avec un faible soutirage (108 %) par rapport au procédé de diffusion. Il permet ainsi des économies significatives de matière et d’énergie surtout pour les étapes d’extraction du jus et de séchage de pulpes. Par rapport au procédé conventionnel, le gain énergétique s’élève à 91,96 × 106 kWh pour une usine traitant 10 000 t/j de betteraves pendant une campagne de 110 jours. De plus, le procédé proposé permet de simplifier la procédure de purification et de réduire de 50 à 60 % la quantité de chaux utilisée. Dans la deuxième partie de cette étude, deux procédés de transformation ont été proposés et optimisés à l’échelle laboratoire pour la valorisation des radicelles et de la pulpe de betterave à sucre. Les radicelles ont été utilisées pour produire du bioéthanol. Le jus brut de radicelles a été extrait par pressage à froid assisté par CEP. La production du bioéthanol a été achevée par fermentation alcoolique. Le prétraitement par CEP (450 V/cm, 10 ms) a permis d’accélérer la cinétique de pressage, d’augmenter le rendement en solutés (79,85 % vs. 16,8 %) et d’obtenir un jus plus concentré (10 % vs. 5,2 %). Le procédé optimisé permet de produire environ 41,75 L de bioéthanol par tonne de radicelles lorsque l’on applique un prétraitement par CEP contre seulement 8,2 L de bioéthanol sans prétraitement électrique confirmant ainsi le potentiel de ce nouveau schéma de valorisation. La pulpe de betterave déshydratée ayant une matière sèche de 92,8 % a été utilisée pour l’extraction de pectines. L’étude réalisée a montré que l’application d’un prétraitement par DEHT permet d’intensifier l’extraction des pectines. Le gain relatif de rendement en pectines est de 25,3 % pour une énergie consommée de 76,2 kJ/kg. Le schéma de bioraffinage proposé pourra aider au maintien de la filière betteravière en France après la suppression de système de quotas sucriers dans l’Union européen qui entrera en vigueur le 1er octobre 2017. / This work discusses the use of electrotechnologies for an optimized valorization of sugar beet according to the concept of biorefinery. The applied electrotechnologies are pulsed electric fields (PEF) and high-voltage electrical discharges (HVED). The study firstly aims at optimizing an alternative method for sugar extraction by PEF assisted cold alkaline pressing. On the other hand, it proposes new ways for valorizing two by-products of sugar beet industry, which are sugar beet tails and pulps. In the first part, PEF treatment combined with liming leads to a better disintegration of beet tissue. It permits accelerating of pressing kinetics, improvement of juice yield and quality, and reduction of subsequent purification procedure. A parametric optimization study identified the best application itinerary of the proposed extraction process. Fresh sugar beet cossettes are pretreated by PEF at 600 V/cm for 10 ms (Q = 2.7 Wh/kg). The electroporated cossettes are then pressed to extract 75% of intracellular juice. Compressed cossettes are subjected to an alkaline pressing with 10% lime milk. In order to extract the residual sucrose in the obtained press-cake, two additional steps of pressing with an intermediate hydration are required. This optimized process allows well exhausting the sugar cossettes (sugar loss of 0.23% and pulp dry matter of 39%) for a short extraction (30 min) and with low draft (108%) compared to diffusion method. Thus, it allows substantial saving in materials and energy especially for juice extraction and pulp drying. Compared to the conventional method, the energy saving amounted to 91.96 × 106 kWh for a sugar beet factory treating 10 000 tons per day for a campaign of 110 days. In addition, the proposed method simplifies the purification procedure of raw juice and reduces the used amount of lime from 50 to 60%. In the second part of this study, two processing methods were proposed and optimized at lab-scale for valorization of sugar beet tails and pulps. Sugar beet tails were used to produce bioethanol. Raw juice of beet tails was extracted by PEF assisted cold pressing. Bioethanol production was then done by alcoholic fermentation. Pretreatment of beet tails with PEF (450 V/cm, 10 ms) permits accelerating the pressing kinetics, increasing the yield of solutes (79.85% vs. 16.8%), and leads to a more concentrated juice (10% vs. 5.2%). The optimized process permits the production of about 41.75 L of bioethanol per ton of beet tails when PEF pretreatment is applied against only 8.2 L of bioethanol without PEF confirming the potential of this new valorization scheme. Dried beet pulp having a dry matter of 92.8% was used for pectin recovery. The present study showed that the application of HVED pretreatment leads to intensify pectin extraction. The relative gain of pectin yield is 25.3% with an energy consumption of 76.2 kJ/kg. The proposed biorefinery scheme could protect the sugar beet industry in France after the suppression of the sugar quota system in the European Union, which will take effect on 1st October 2017.

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