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Redzuan, Norizah. "Cold plasma air decontamination." Thesis, University of Glasgow, 2010. http://theses.gla.ac.uk/2286/.
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Cold Plasma Discharges offer wide decontamination scenarios relevant to environmental, food and drink or clean room applications. The option to operate the discharge system in atmospheric or sub-atmospheric condition provides an opportunity to investigate a lowcost and simple system design. UV to NIR (200nm to 700nm) can be emitted by pulsed cold plasma discharge systems that operate at atmospheric pressure. Different wavelengths emitted from the discharge depend on the pressure and the type of gas mix used in the systems. The scope of the work involved in this research was to design and develop a prototype cold plasma system for air at atmospheric pressure. The prototype was used for air decontamination by passing seeded and unseeded air between the electrodes gap. Modelling of the discharge and pulse forming network circuit systems was carried out in MultiSim to investigate the circuit characteristic. The components values ie: capacitors, stray inductors and resistors in the model system are interchangeable which enabled simulation of individual component effects on the output pulse shape and magnitude. The optimum component properties from the modelling were used as a guide to designing the system. The main discharge system contained a pair of Chang Uniform Field Electrodes which were manufactured in-house, and provided a discharge area of 1.0cm x 60.0 cm. The discharge volume is varied depending on the gap between of the anode and cathode. Preionisation was achieved via trigger wire, built within the discharge system. This promotes the ionisation of the gas in between the electrodes in enhancing uniform discharge characteristics. Different types of electrodes were made from aluminium with the discharge size 300mm x 200mm, laser marked and unmarked surface were also used in the system in order to obtain wider discharge surface and reduce manufacturing costs.
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Liu, Jingjing. "Generation and characterisation of cold atmospheric liquid-containing plasmas." Thesis, Loughborough University, 2011. https://dspace.lboro.ac.uk/2134/7761.
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This thesis presents an experimental study of non-thermal atmospheric pressure gas plasmas in presence of liquid as an efficient source of transient and reactive species to initiate chemical reactions necessary for many important applications. Two types of liquid-containing plasmas are considered: discharges formed between a needle electrode and a liquid electrode, and plasma jets formed in a water vapour flow mixed in helium or argon gas. Two plasma modes (the pulsed and the continuous mode) are observed in the needle-to-liquid plasma. A comparative study of the needle-to-liquid plasma in the continuous mode with DC and AC excitations reveals that the plasmas are glow discharges, and AC excited plasmas have the highest energy efficiency. A study of helium/water vapour plasma jet shows that “plasma bullets” are formed even with water vapour in the gas mixture, but become quenched when the moist helium flow rate is above 300sccm (~1800ppm water concentration). Moderate amount of water vapour (~250ppm water concentration) is beneficial for active species production mainly due to the high electron density. Hydrogen peroxide production in saline solution with three different plasma sources is investigated due to the importance of H2O2 in several important applications. Long lifetime of H2O2 in the liquid after plasma treatment indicates an exciting possibility of plasma pharmacy.
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PIFERI, CECILIA. "Cold plasmas for air purification and sanitation." Doctoral thesis, Università degli Studi di Milano-Bicocca, 2023. https://hdl.handle.net/10281/402359.
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È comunemente accettato che il cambiamento climatico sia dovuto ad un effetto antropico. Gli agenti inquinati sono sicuramente responsabili del peggioramento della qualità della vita umana ed è necessario trovare una soluzione. Una importante classe di inquinati è quella dei Composti Organici Volatili (VOC). Molti di questi composti sono classificati come cancerogeni o possibili cancerogeni per le persone, oltre al fatto che possono causare danni a lungo termine sull'ambiente. Nonostante questi problemi, i VOC sono necessari nelle vernici di pareti o arredi, nei trattamenti dei tessuti e sono largamente utilizzati nei processi industriali, per poi essere rilasciati nell'ambiente come prodotti di scarico. Al momento, però, non è possibile sostituirli con altri composti meno dannosi, pertanto è necessario concentrarsi sulla loro degradazione dopo la diffusione nell'aria. Il modo più facile è tramite i reattori di combustione, ma sono molto ingombranti, richiedono molta energia ed è necessario raggiungere temperature superiori ai 300°C per essere efficaci. I plasmi a pressione atmosferica, in particolare le Surface Dielectric Barrier Discharge (SDBD), possono essere di aiuto nel miglioramento dell'abbattimento dei VOC. Infatti le SDBD richiedono molta meno energia dei tipici reattori di combustione, occupano volumi molto minori (generalmente meno di un metro cubo) e la temperatura globale del gas è dell'ordine della temperatura ambiente.
L'inquinamento da agenti chimici non è l'unico problema che dobbiamo affrontare per migliorare la qualità della vita. L'antibiotico resistenza è un problema crescente. I farmaci antibiotici hanno migliorato nettamente le condizioni di salute sin dal momento in cui sono stati scoperti, ma stanno diventando via via sempre meno efficienti a causa dell'uso improprio che è stato fatto negli ultimi decenni. Un modo per contrastare l'uso di antibiotici è quello di ridurre o eliminare le cariche batteriche presenti nell'aria, ad esempio usando filtri antiparticolato nei sistemi di ventilazione. In questo modo però gli agenti biologici sono raccolti nei filtri in modo passivo; vengono accumulati, possono proliferare sul lungo periodo specialmente in presenza di alta umidità (>80%), e venire successivamente ridiffusi. Parte di questa tesi si occupa di studiare una possibile soluzione a questo problema. Si fa uso di una SDBD in modo innovativo per ridurre la concentrazione di batteri nell'aria. Il volume ridotto delle SDBD permette di inserire questo sistema all'interno dei sistemi di ventilazione e di ridurre attivamente la carica microbica al loro interno.
L'ultima parte della tesi si concentra sulla modifica di superfici polimeriche attraverso l'uso di un plasma freddo capacitivo a bassa pressione. Negli ultimi decenni si sta sviluppando un crescente interesse nei materiali nanostrutturati. Tramite il plasma è possibile creare una nanostrutturazione sulle superfici polimeriche per diverse applicazioni, come ad esempio superfici antifouling in acqua o antibatteriche in aria.It is generally accepted that the reduction of life quality is largely due to anthropic effects, mainly due to pollutant agents, and possible solutions need to be addressed. An important class pollutants are the so-called Volatile Organic Compounds (VOCs). Many of these compounds are classified as carcinogenic, or possibly carcinogenic, for humans and, in addition, they can cause long term environmental damage. Despite these drawbacks, they are suitable for wall and/or furniture painting, for the textile treatments, and are widely used in a variety of industrial processes. Unfortunately, they are released into the environment as waste products. As of today, it is not possible to replace VOCs with other compounds, but one can attempt to modify them just before they get disseminated in the atmosphere. The easiest way to achieve that goal is by using combustion reactors. However, they are bulky, require a lot of energy and need to reach high temperatures up to 300°C, or more, to be effective. Atmospheric pressure cold plasmas, in particular Surface Dielectric Barrier Discharge (SDBD), can largely improve the abatement process of VOCs. Indeed, SDBD require much less energy than typical combustion reactors, they occupy much smaller volumes (less than a cubic meter) and the global gas temperature gets down to the order of room temperature. Chemical pollution is not the only problem affecting our living environment, for instance antimicrobial resistance is also becoming an important issue. The antimicrobial and antibacterial drugs have improved our health conditions since they were discovered, but they are becoming less and less effective as a result of their improper use during the last decades. A way to reduce the use of antibiotic can be obtained by eliminating or hindering microbial diffusion in air, such as using particulate filters in ventilation systems. However, the biological agents collected in the filters are not just passive, but get accumulated on the filter surface, thus proliferating during long periods of high relative humidity (>80\%), causing infections at distant places after dissemination. Part of this thesis is devoted to this problem. An innovative use of the SDBD was developed for the abatement of bacteria in air. Its limited volume permits to place the SDBD in contact with the air circulating system of a building, within which one can proceed to the denaturation of the diffusing bacteria by the reactive species produced in the plasma. Finally, the last part of this thesis is devoted to polymeric surfaces modifications through a capacitive coupled low pressure cold plasma. Surface modifications of materials by plasma treatments and depositions have attracted a great deal of interest in the last decades. We can create a nanostructurization over the polymeric treated surfaces that can have different applications, from antifouling in water to antibacterial in air.
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Honnorat, Bruno. "Application of cold plasma in oncology, multidisciplinary experiments, physical, chemical and biological modeling." Thesis, Sorbonne université, 2018. http://www.theses.fr/2018SORUS014/document.
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« La médecine- plasma» est le domaine de recherche décrivant les applications médicales des plasmas, principalement à pression atmosphérique. Les plasmas froids sont un état de la matière caractérisé par la présence d'électrons libres ayant une énergie cinétique de plusieurs eV alors même que les ions et les neutres peuvent être à température ambiante. Cet état transitoire, hors équilibre thermique, produit des espèces chimiques très réactives. L’objectif de ce travail multidisciplinaire a été d’évaluer le potentiel anti-tumoral des plasmas-froids. Deux types de dispositifs ont été conçus et fabriqués par impression 3D: des Décharges à Barrière Diélectrique et des jets plasmas. Des études in-vitro et in-vivo ont été menées avec les lignées cellulaires TC1 et CT26. La production d’espèces réactives produites dans un liquide exposé à un plasma a été étudiée afin de comprendre les résultats in-vitro et de comparer les dispositifs plasma entre eux. Différents dispositifs à plasmas ont été réalisés afin d’étudier in-vivo, l’effet de l’énergie déposée lors du traitement sur la peau et les tumeurs. Afin de limiter l’échauffement cutané et les lésions induites un dispositif refroidi à l’azote liquide a été développé. Enfin, une simulation numérique modélisant les transferts thermiques des tumeurs et tissus sous exposition plasmas a permis de quantifier l’hyperthermie et les lésions associées en validant le modèle sur des résulats expérimentaux. Une revue critique d’études in-vivo de « médecine plasma » publiées dans la littérature est proposée afin d’évaluer le rôle de l’hyperthermie dans les effets thérapeutiques observésPlasma-medicine is the field of research describing the medical applications of plasmas, mainly at atmospheric pressure. Cold plasmas are a state of matter characterized by the presence of free electrons with a kinetic energy of several electron volts even though the ions and neutrals may be at room temperature. This transient state, apart from thermal equilibrium, produces highly reactive chemical species. The objective of this multidisciplinary work was to evaluate the anti-tumor potential of cold plasmas. Two types of devices have been designed and manufactured by 3D-printing: Dielectric Barrier Discharge and plasma-jets. In-vitro and in-vivo studies were conducted with TC1 and CT26 cell lines. The production of reactive species produced in a liquid exposed to plasma has been studied in order to understand the in-vitro results and to compare the plasma devices with those of other teams. Various plasma devices have been made to study the effect of the energy deposited during the in-vivo treatment of skin and subcutaneous tumors. A device cooled with liquid nitrogen has been developed to limit skin damage induced by heating. Finally, a numerical simulation modeling the heat transfers of tumors and tissues under plasmas exposure enables to quantify the hyperthermia and the associated lesions by validating the model on experimental results. A critical review of in-vivo plasma-medicine studies published in the literature is proposed to evaluate the role of hyperthermia in the therapeutic effects reported
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Rezende, Dulce Cristina Jacinto. "Plasma ultrafrio em armadilha atômica." Universidade de São Paulo, 2005. http://www.teses.usp.br/teses/disponiveis/76/76131/tde-11112013-102236/.
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Neste trabalho nós produzimos um plasma neutro ultrafrio de 85Rb através da fotoionização dos átomos aprisionados em uma armadilha magneto-óptica. Medimos o número de partículas que evaporam do plasma no momento de sua criação usando a técnica de tempo-de-vôo. A partir disto realizamos o estudo da taxa de evaporação com relação a energia cinética inicial do elétron fornecida ao sistema, onde para isto criamos o plasma com diferentes comprimentos de onda do laser de fotoinização. Nossos resultados indicam que conforme fornecemos mais energia ao sistema mais partículas evaporam e constatamos que está de acordo com a literatura. Interpretamos o resultado com um modelo analítico que considera a distribuição de energia de Maxwell-Boltzmann e encontramos a temperatura do plasma com relação a temperatura inicial dos elétronsIn this work we produced an ultracold neutral plasma of 85Rb formed by the photoionization of laser-cooled atoms. We measured the number of particles evaporated from the plasma in the moment of its formation using the time-of-flight technique. After this, we studied the evaporation rate as a function of the initial electron kinetic energy, for this we created the plasma at different wavelengths of the photoinization laser. Our results indicate that as we supplied more energy to the system more particles evaporate and we verified that it is in agreement with the literature. We interpreted the result with an analytic model that considers the Maxwell-Boltzmann energy distribution and we found the plasma temperature as a function initial electron temperature
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Schmitt, Andreas. "Spin-one color superconductivity in cold and dense quark matter." [S.l. : s.n.], 2004. http://deposit.ddb.de/cgi-bin/dokserv?idn=974955094.
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Zhou, Renwu. "Direct and indirect activation of biological objects using cold atmospheric plasma." Thesis, Queensland University of Technology, 2019. https://eprints.qut.edu.au/131872/2/Renwu%20Zhou%20Thesis.pdf.
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This project was a step forward in the development and application of chemically reactive physical plasmas for direct and indirect treatment of biological objects. The project unravelled the link between plasma-generated chemistry and resultant bioactivity, so as to improve the cold plasma devices for specific applications. The project investigated the interactions of cold plasmas with biological objects including plant seeds, living cells and microorganisms, to provide some theoretical and experimental bases for the development of plasma applications.
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Schulze, Robert. "From hot lattice QCD to cold quark stars." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2011. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-65426.
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A thermodynamic model of the quark-gluon plasma using quasiparticle degrees of freedom based on the hard thermal loop self-energies is introduced. It provides a connection between an established phenomenological quasiparticle model – following from the former using a series of approximations – and QCD – from which the former is derived using the Cornwall-Jackiw-Tomboulis formalism and a special parametrization of the running coupling.
Both models allow for an extrapolation of first-principle QCD results available at small chemical potentials using Monte-Carlo methods on the lattice to large net baryon densities with remarkably similar results. They are used to construct equations of state for heavy-ion collider experiments at SPS and FAIR as well as quark and neutron star interiors. A mixed-phase construction allows for a connection of the SPS equation of state to the hadron resonance gas.
An extension to the weak sector is presented as well as general stability and binding arguments for compact stellar objects are developed. From the extrapolation of the most recent lattice results [Baz09, Bor10b] the existence of bound pure quark stars is not suggested. However, quark matter might exist in a hybrid phase in cores of neutron stars.
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Köritzer, Julia. "Biophysical effects of cold atmopheric plasma on glial tumor cells." Diss., Ludwig-Maximilians-Universität München, 2013. http://nbn-resolving.de/urn:nbn:de:bvb:19-162120.
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Bekeschus, Sander [Verfasser]. "Effects of cold physical plasma on human leukocytes / Sander Bekeschus." Greifswald : Universitätsbibliothek Greifswald, 2015. http://d-nb.info/1072492830/34.
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Siddique, Shaikh. "Cold plasma inhibits growth and germination of avocado postharvest pathogens." Thesis, Siddique, Shaikh (2018) Cold plasma inhibits growth and germination of avocado postharvest pathogens. PhD thesis, Murdoch University, 2018. https://researchrepository.murdoch.edu.au/id/eprint/50154/.
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Cold plasma (CP) is composed of highly reactive species including gas molecules, charged particles in the form of positive ions, negative ions, free radicals and electrons at near-room temperature. CP has been demonstrated to successfully decontaminate food materials from food-borne pathogens at atmospheric pressure and offers new chemical-free sterilisation opportunities for the food sector. The efficacy of CP to control postharvest fungal pathogens is poorly studied. This study investigated the effects of CP generated in both open and sealed conditions, on the growth of Colletotrichum alienum and C. fioriniae, two important postharvest fungal pathogens of avocado (Persea americana cv. ‗Hass‘). In addition, plasma activated water (PAW) was tested on C. alienum. In vitro, mycelial growth and conidia germination decreased as the duration of CP treatment increased, with no mycelial growth or germination of conidia occurring after 6 min of treatment. PAW also decreased conidial germination, even when the PAW had been stored for 15 days prior to use. Optical emission spectroscopy identified production of active oxygen and nitrogen species during CP treatment. These were assumed to be responsible for the observed reduction in conidial germination. Transmission electron microscopy showed the majority of conidia treated with CP and PAW were deformed, with changes to the cell wall, and disorganised vacuoles and cytoplasm. In addition, some conidia also had disrupted nuclei and mitochondria after both treatments. In planta, CP treatment for up to 5 min was not phytotoxic to avocado fruit, and fruit were firmer compared to untreated and fungicide treated controls. However, significant variability was observed in individual fruit response to CP. CP treatment appeared to reduce postharvest body rot and stem end rot symptoms but this was not significantly different to the untreated control. It was assumed that CP either slowed the growth of the pathogens in the treated fruit or delayed the ripening of the fruit. These data suggest that cold plasma has the potential to be applied as a postharvest treatment for C. alienum and C. fioriniae on avocado fruit, and may contribute to reducing food wastage caused by these pathogens.
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Mollart, T. P. "Electron emission processes in cold cathode thermal arcs." Thesis, Durham University, 1993. http://etheses.dur.ac.uk/5546/.
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In this Thesis the processes of electron emission from cathode electrodes are studied theoretically, and the applicability of these mechanisms to the non refractory cathodes that can be used to sustain thermal arcs was examined. Apparatus that was used to generate and manipulate thermal arcs along rail electrodes is described in this thesis. Techniques for driving arcs over polished sample electrodes with magnetic or aerodynamic forces are outlined. Scanning electron microscopy was used to study emission site formation on highly polished electrodes with a natural 2.5 nm oxide layer. Theoretical maximum electron current densities that can be extracted by the arc were calculated and these were used, in conjunction with information from the experimental work, to make estimates of the lifetime of emission spots that are seen on the cathode electrodes of thermal arc devices. The lifetime was found to be dependent on the arc velocity over a range of velocity values from 3 to 80 ms(^-1). The lifetime measured ranged from 2.4 µs to 0.024 µs. Experiments on arcs driven at a constant velocity using a combination of aerodynamic and magnetic forces showed that the formation of emission spots was independent of die applied external magnetic field. The presence of artificially grown copper (11) oxide layers, 50 nm and 100 nm thick, were found to influence the lifetime. The effect of the oxide layer was predicted using a simple model accounting for the change of resistance that such an oxide layer would be expected to cause. Additional experiments showed that the resistance of the arc was independent of the oxide layer thickness, as predicted by the model.
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Varnasseri-Ghandali, Mehrvash. "Properties of a novel molecular ultra-cold laser produced Rydberg plasma." Thesis, University of Manchester, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.525929.
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Boxhammer, Veronika. "Developmant of a safe therapeutic window for cold atmospheric plasma treatments." Diss., Ludwig-Maximilians-Universität München, 2014. http://nbn-resolving.de/urn:nbn:de:bvb:19-177756.
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Bayliss, Danny. "Understanding the inactivation mechanism of foodborne pathogens using cold atmospheric plasma." Thesis, Loughborough University, 2012. https://dspace.lboro.ac.uk/2134/12844.
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Experimental studies into the use of cold atmospheric plasmas for inactivating foodborne pathogens are presented in this thesis. Eliminating the possibility that treatment delivered by a plasma to a population or assemblage of micro-organisms is unevenly distributed is an essential pre-requisite to attempting to interpret inactivation kinetics with a view to elucidating mechanisms of inactivation. A filtration method of depositing cells evenly on the surface of a membrane without cell stacking was developed and used throughout the work described here. Two atmospheric plasma systems were evaluated and each brought about microbial inactivation in a distinct way. A pulsed radio frequency plasma jet operated at 3.47 MHz caused gross morphological changes to L. innocua whereas a low frequency air mesh plasma system operated at a frequency of 24 kHz led to the inactivation of these bacteria without inducing observable structural changes. Changing the operating parameters of the plasma jet system had a significant effect on the composition of the reactive plasma species generated as revealed by changes to the mode of inactivation of bacteria. In addition to inactivating bacteria, the pulsed plasma jet was shown to be highly effective in degrading and removing amyloid aggregates from the surface of mica coupons. Amyloids have widely been used as a non-infectious model for prions, and the results obtained here show potential for the application of gas plasma technology for removing prions from abiotic surfaces in medical and other applications. It has widely been assumed that bacterial envelopes are the principal sites at which reactive plasma species bring about damage to cells. However, changing the composition of the bacterial membranes of E. coli and Listeria innocua by cultivating them at widely different temperatures to induce changes proved not to result in enhanced inactivation. Flow cytometry was also used to provide additional insights into possible mechanisms of inactivation. The following fluorescent dyes were used either singly or in combination; SYTO 13, DiBAC4(3), cFDA and PI. The results obtained with the dyes DiBAC4(3) and PI showed that Gram positive bacteria became depolarised prior to the bacterial membrane becoming compromised, possibly suggesting that the inactivating plasma species are affecting membrane proteins responsible for maintaining the bacterial charge. Differences between the fluorescent dye staining of Gram negative and Gram positive species were obtained using SYTO13 and PI demonstrating that the different membrane structures affect their interaction with the plasma. In additional studies, the air mesh plasma was used to treat multi-drug resistant strains of Methicillin resistant Staphylococcus aureus (MRSA) in an attempt to reverse antibiotic resistance. MRSA PM 64 was shown to reverse its antibiotic resistance to Oxacillin, Kanamycin and Trimethoprim. Culturing the bacteria in a nutrient limited media led to increased resistance towards plasma treatment and maintenance of their high levels of antibiotic resistance.
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Peillon, Etienne. "Simulation and analysis of sign-changing Maxwell’s equations in cold plasma." Electronic Thesis or Diss., Institut polytechnique de Paris, 2024. http://www.theses.fr/2024IPPAE004.
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De nos jours, les plasmas sont principalement utilisés à des fins industrielles. L'un des exemples les plus fréquemment cités d'utilisation industrielle est la production d'énergie électrique via des réacteurs nucléaires à fusion. Pour contenir le plasma correctement à l'intérieur du réacteur, un champ magnétique est imposé en arrière-plan, et la densité et la température du plasma doivent être précisément contrôlées. Cela est effectué en envoyant des ondes électromagnétiques à des fréquences et dans des directions spécifiques en fonction des caractéristiques du plasma.La première partie de cette thèse de doctorat est consacrée à l'étude du modèle du plasma avec un fort champ magnétique en arrière-plan, ce qui correspond à un métamatériau hyperbolique. L'objectif est d'étendre les résultats existant en 2D au cas 3D et de dériver une condition de radiation. Nous introduisons une séparation des champs électriques et magnétiques ressemblant à la décomposition TE et TM habituelle, puis nous présentons quelques résultats sur les deux problèmes résultants. Les résultats sont dans un état très partiel et constituent un brouillon approximatif sur le sujet.La deuxième partie étudie l'EDP dégénérée associée aux ondes résonantes « lower-hybrid » dans le plasma. Le problème aux limites associé est bien posé dans un cadre variationnel « naturel ». Cependant, ce cadre n'inclut pas le comportement singulier présenté par les solutions physiques obtenues via le principe d'absorption limite. Ce comportement singulier est important du point de vue physique car il induit le chauffage du plasma mentionné précédemment. Un des résultats clés de cette deuxième partie est la définition d'une notion de saut à travers l'interface à l'intérieur du domaine, ce qui permet de caractériser la décomposition de la solution d'absorption limite en parties régulière et singulièreNowadays, plasmas are mainly used for industrial purpose. One of the most frequently cited examples of industrial use is electric energy production via fusion nuclear reactors. Then, in order to contain plasma properly inside the reactor, a background magnetic field is imposed, and the density and temperature of the plasma must be precisely controlled. This is done by sending electromagnetic waves at specific frequencies and directions depending on the characteristics of the plasma.The first part of this PhD thesis consists in the study of the model of plasma in a strong background magnetic field, which corresponds to a hyperbolic metamaterial. The objective is to extend the existing results in 2D to the 3D-case and to derive a radiation condition. We introduce a splitting of the electric and magnetic fields resembling the usual TE and TM decomposition, then, it gives some results on the two resulting problems. The results are in a very partial state, and constitute a rough draft on the subject.The second part consists in the study of the degenerate PDE associated to the lower-hybrid resonant waves in plasma. The associated boundary-value problem is well-posed within a ``natural'' variational framework. However, this framework does not include the singular behavior presented by the physical solutions obtained via the limiting absorption principle. Notice that this singular behavior is important from the physical point of view since it induces the plasma heating mentioned before. One of the key results of this second part is the definition of a notion of weak jump through the interface inside the domain, which allows to characterize the decomposition of the limiting absorption solution into a regular and a singular parts
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Adikaram, Mudiyanselage Janith S. "Nanomaterial synthesis and surface treatment by atmospheric pressure cold plasmas." Thesis, Queensland University of Technology, 2022. https://eprints.qut.edu.au/232838/1/Janith_Adikaram%20Mudiyanselage_Thesis.pdf.
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The main goal of this study was to demonstrate the potential of atmospheric pressure cold plasmas to synthesize nanoparticles and surface treatments. Silver nanoparticles and carbon quantum dots were selected for this work. The use of silver nanoparticles in bactericidal applications has been tested. In addition, carbon quantum dots are used to manufacture a low-cost metal ion sensor for the detection of copper in drinking water. The second part of the study investigated the chemical reactions that occur in plasma treated mesoporous tin oxide films. These are used to increase the efficiency of dye sensitized solar cells.
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Young, Kevin. "Equivalent circuit modeling of TMS plasma polymer coating system on cold-rolled steel." Diss., Columbia, Mo. : University of Missouri-Columbia, 2004. http://hdl.handle.net/10355/4104.
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Thesis (M.S.) University of Missouri-Columbia, 2004.The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file viewed on (June 30, 2006). Vita. Includes bibliographical references.
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Schmidt-Bleker, Ansgar [Verfasser]. "Investigations on Cold Atmospheric Plasma Jets for Medical Applications / Ansgar Schmidt-Bleker." Greifswald : Universitätsbibliothek Greifswald, 2016. http://d-nb.info/1111579261/34.
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Delaux, Joakim. "Activation de biopolymères par plasma atmosphérique non thermique." Thesis, Poitiers, 2016. http://www.theses.fr/2016POIT2310.
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L'équipe de François Jérôme (IC2MP, UMR7285) a développé des procédés innovants et originaux dans les prétraitements de la biomasse lignocellulosique. Ces travaux fondamentaux sont basés sur l'utilisation de plasma atmosphérique non-thermique afin de dépolymériser des biopolymères (cellulose, amidon, inuline) de manière sélective. L'avantage de ce prétraitement physique est son absence de solvant et de catalyseur permettant ainsi de pallier les problèmes de purification ou de dilution habituellement rencontrés. On peut également citer la faible consommation énergétique. Ce prétraitement plasma permet d'accroitre l'accessibilité des biopolymères aux espèces réactives (lors d'une hydrolyse par exemple) et d'obtenir des rendements supérieurs aux procédés chimiques ou enzymatiques classiques.L'objectif de cette thèse est de comprendre quelles sont les bonnes conditions pour obtenir une cellulose moins réfractaire aux traitements chimiques et quel mécanisme est mis en jeu lors du traitement par plasma. Quels impacts ont les espèces qui interagissent avec la surface du biopolymère, comment elles diffusent au cœur des matrices polymériques ou encore quel est l'impact de la nature chimique du/des biopolymère(s) (cristallinité, type de liaisons, nature des saccharides…). Par la suite, une étude sur la réactivité de la cellulose traitée par plasma a été réalisée en se concentrant plus particulièrement sur les rendements en glucose suite à une hydrolyse acide en milieu dilué. Cela nous a permis d'évaluer l'impact des traitements physiques (plasma, broyage ou les deux) sur la réactivité de la cellulose. De plus, un panel d'analyses a été réalisé et nous a permis d'en déduire un mécanisme réactionnel possible pour le traitement de la cellulose par plasmaFrançois Jerome's team developed new processes for the pretreatment of lignocellulosic biomass. This fundamental work is based on the use of non-thermal atmospheric plasma for the deplolymerization of biopolymers (cellulose, inuline) selectively. The advantage of this physical pretreatment is the non-using of catalysis or solvent and so it's resolve the dilution problem or the purifying problem usually met. A low consummation of energy can be cited too. This pretreatment could be increase the reactivity of biopolymers (hydrolysis for example) and get a better yield than the chemical or enzymes processes.The goal of the thesis is to understand what are the good conditions to obtain a cellulose more reactive for the chemical reactions and what the mechanism for the plasma treatment are. What kind of species react with the surface of the polymers and how they enter in the bulk ? What is the role of the nature and constitution (crystallinity, different polymer, kind of link…) ? Then, a study on the reactivity of the plasma cellulose was performed and the focus was put on the yield of glucose after acid hydrolysis. Like this, we can see the influence of the physical pretreatment (plasma, milling or both) on the cellulose. At the end, a mechanism is proposed by using all the information recovered in particularly with the structural analysis
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Müller, Meike [Verfasser], and Gregor [Akademischer Betreuer] Morfill. "Characterisation of cold atmospheric plasma afterglow for decontamination / Meike Müller ; Betreuer: Gregor Morfill." München : Universitätsbibliothek der Ludwig-Maximilians-Universität, 2019. http://d-nb.info/1198112034/34.
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Bres, Lucie. "Interaction entre un plasma froid à la pression atmosphérique et des surfaces thermoplastiques industrielles : application à l'activation de surface." Thesis, Toulouse 3, 2017. http://www.theses.fr/2017TOU30273/document.
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Le développement dans l'industrie aéronautique des composites à matrices organiques renforcés par des fibres de carbone se justifie entre autres par leur très bonne capacité à transférer les efforts mécaniques élevés en rapport de leur faible masse. Les matrices Poly-EtherEtherCétone (PEEK) sont des candidates idéales pour les applications structurales en raison de leurs bonnes propriétés chimiques, mécaniques, ainsi que d'une stabilité thermique supérieure à d'autres polymères. Cependant celles-ci présentent des inconvénients majeurs pour la phase de mise en peinture, à savoir une faible réactivité de surface et une inertie chimique importante qui impliquent le développement d'un procédé d'activation de surface avant toute étape de revêtement. Ce travail se concentre sur une technologie de plasma froid à la pression atmosphérique développée par la société AcXys Technologie(r) : le module ULS en post-décharge. Cette technologie, choisie sur la base de considérations industrielles et environnementales, vise à garantir une activation de surface efficace, sans détérioration des propriétés intrinsèques de la matrice polymère. L'objectif de ce travail est alors d'améliorer la compréhension des mécanismes d'activation par plasma menant à une meilleure adhésion à l'interface composite PEEK/revêtement industriel. Des caractérisations électriques et optiques de la décharge et de la post-décharge nous permettront de mieux comprendre le fonctionnement intrinsèque de l'équipement. Tandis que la caractérisation des modifications de surface (de nature chimiques, physiques et/ou physico-chimiques), notamment au travers de la mouillabilité et de l'acido-basicité, permet d'appréhender l'influence des paramètres opératoires et du gaz plasmagène utilisé. Dans la perspective de mieux spécifier les conditions optimales d'utilisation industrielles, nous évaluons dans cette étude la pertinence de l'utilisation de la notion de dose plasma pour ce procédé, notion représentative de l'ensemble des paramètres opératoires. Cette notion, communément rencontrée dans d'autres procédés, est revue et développée pour correspondre à notre cas d'étude. Son utilisation permet une juste comparaison entre des configurations d'activation différentes puisqu'elle rend compte à la fois de la puissance dissipée sur le substrat et du temps d'interaction plasma/surface. Afin de valider la dose plasma exprimée pour notre équipement, nous introduisons des mesures d'adhérence effectuées entre le composite activé et le revêtement. Les résultats laissent entrevoir des perspectives d'améliorations dans les procédés industriels d'activation de surfaceCarbon Fiber Reinforced Polymer (CFRP) using thermoplastic polymer matrices as Poly-EtherEtherKetone (PEEK) for example, are increasingly being used in structural engineering due to their light weight coupled with good mechanical properties. In aeronautic industry, the adhesive bonding of these composites is often required. However, their low surface energy motivates the development of robust and reliable surface activation treatments aiming at increasing the surface reactivity before painting. For this reason, we have used an atmospheric pressure plasma torch developed by AcXys Technologies(r). It is a remote plasma, well known to be an effective process to improve surface reactivity without deterioration of the bulk matrix properties. This easily implementable technology attracts many industries looking for a cost-effective and eco-friendly surface activation process. The aim of this work is to contribute to the understanding of plasma activation mechanisms leading to a greater and a more durable adhesion between PEEK matrix and an industrial painting. This study provides some insight into the effects of process parameters (device power, distance between nozzle and substrate, etc) on adhesion improvement. Mechanisms which are attributed to it are investigated by means of three point bending and crosscut adhesion standard tests. Results are discussed with respect to surface properties characterized by wettability measurements including acid-base approach, X-ray Photoelectrons Spectroscopy and Atomic Force Microscopy. In order to facilitate industrialization of atmospheric pressure remote plasma as surface activation technique, this study proposes a new approach aiming at allowing a better and more equitable comparison between atmospheric pressure plasma processes. This comparison is made through the "plasma dose" expression, similar to the one commonly used in Corona process. It is applicable for one plasma gas and accounts for both received energy and interaction time of the post-discharge with the surface. Mechanisms assigned to improvement of adhesion will be more appreciated and their characterization will contribute to a greater definition of industrial surface preparation range by remote plasma
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Coulombe, S. (Sylvain). "A model of the electric arc attachment on non-refractory (cold) cathodes /." Thesis, McGill University, 1997. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=34710.
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In this work, a physical model describing the electric arc attachment on electron emitting non-refractory (cold) cathodes is developed and applied to Cu, Fe and Ti cathodes. The model considers the possibility of a pressure build up in the cathode region due to the strong vaporization of the cathode, the formation of a cathode sheath according to the Bohm's model, and the ion-enhanced thermo-field emission of electrons by the cathode surface. The self-sustaining operating conditions of the discharge are defined by two simple criteria based on particle and energy balance considerations. Results clearly show the necessity of having high local metallic vapor pressures in the cathode region of non-refractory cathodes in order to have a self-sustaining arc attachment. A minimum pressure of at least 19 atm is needed for a Cu cathode. This minimum pressure is shown to decrease as the cathode material boiling temperature increases according to an exponential decay law. Current densities of the order of 1010 A m--2 are maintained at the surface of a Cu cathode mainly by the emitted electrons. A comparison of the three different models for the electron emission current found in the literature allowed to define the limits of validity of each model for two typical arc-cathode interaction systems, and to evaluate the underestimation made on the emission current density when a less appropriate model is used. This underestimation is shown to cause an overestimation of important parameters such as the cathode surface temperature and metallic vapor pressure in the cathode region. An analysis of the mechanisms of heat transfer to the cathode surface allowed to show that the confinement of the cathode spot plasma forming the arc attachment could favor the production of vapors to the detriment of liquids. Such a phenomenon is of importance in Arc Ion Plating for instance. Heat losses by conduction in the cathode bulk larger than 1010 W m--2 are shown to favor the formation of liquid
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Elhenshir, Omar Said Ali. "Cold atmospheric plasma : studies on inactivation mechanisms in food-borne pathogens and laboratory strains." Thesis, University of Nottingham, 2013. http://eprints.nottingham.ac.uk/28391/.
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Food-borne disease remains accountable for high levels of morbidity and mortality in the world. The World Health Organization (WHO) estimated that food-borne and water-borne diarrhoeal diseases kill about 2.2 million people annually (SGM, 2013). In this thesis, studies on microbial inactivation were carried out using Cold Atmospheric plasma (CAP) generated by a radiofrequency (RF) source at RF = 4.6 MHz. The operating gas used was a mixture of helium and oxygen. The study has investigated the effect of CAP on different strains of food-borne bacteria. These included strains/mutants of S. typhimurium, L. monocylogenes and E. coli. The result has shown that CAP has the capability to inactivate a wide range of food-borne bacteria. However, S. typhimurium LT2, E. coli 0157: H7 and E. coli HI 0407 showed more tolerance to CAP treatment than L. monocytogenes strains and E. coli K-12 MG 1655. This result led to further investigations into the role of lipopolysaccharide (LPS) structure in the tolerance to CAP treatment. To investigate the role of LPS structure, derivatives of E. coli K-12 which lack the O-antigen and isogenic mutants of them (core polysaccharide defective) were used. In addition to these strains and mutants, partially and fully restored LPS derivatives of E. coli K-12 MG1655 and S. typhimurium TA98 which is a mutant of S. typhimurium LT2 were also used. No significant differences in the sensitivity to CAP treatments between these mutant and their parental strains were found except between S. typhimurium TA98 and its parental strain. S. typhimurium TA 98 was missing many other genes, therefore it was not comparable to the parental strain. The results suggest no role for the LPS structure regions in the resistance to CAP treatment. The study has also investigated the role of oxidative stress in bacterial inactivation. Mutants of E. coli K-12 BW25113 were a single gene of the OxyR regulated genes has been deleted, were used. Three mutants were found significantly (P < 0.05) more sensitive to CAP treatments than other strains. These mutants were (delta dps), (delta grxA) and (delta sufC). The gene deleted from each mutant is hydrogen peroxide inducible and OxyR regulated (Zheng et al., 2001a). Since each of these genes has an important role in the resistance to oxidative stress, the result suggests the involvement of oxidative stress in inactivation by CAP treatments. To confirm these results and to find out whether the CAP treatment caused DNA damage or mutagenic effects, the Ames strains were used. Exposure to CAP treatment for 5 and 10 seconds caused a significant (P < 0.05) increase in the number of revertant colonies of S. typhimurium TA 100 and S. typhimurium TAI02. The results suggest that CAP caused base-pair substitution in the DNA of S. typhimurium TA 100 (Barnes et al., 1982) and transition/transversion mutations in the DNA of S. typhimurium TA 102 (Levin el al., I 982a) and potentially in the DNA of other bacteria. It can be concluded that CAP inactivates bacteria due to oxidative stress damage and induces mutation in the bacterial DNA. Modification of the Ames strain test was successfully validated. This finding highlights some concerns about application of CAP in dental and wound treatments.
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Lovascio, Sara. "Cold Plasma deposition of organosilicon films with different monomers in a dielectric-barrier discharge." Phd thesis, Université Pierre et Marie Curie - Paris VI, 2010. http://tel.archives-ouvertes.fr/tel-00815260.
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Cette thèse porte sur une étude fondamentale sur le dépôt des couches minces d'organosiliciés par des Décharges à Barrière Diélectrique (DBD), un procédé très intéressant pour l'application aux textiles. La plupart des dépôts des couches d'oxyde de silicium sont déposées à partir du précurseur hexaméthyle silixone (HMDSO).De plus très peu d'études sont consacrées aux mécanismes de dépôt des couches à la pression atmosphérique. Dans cette étude les propriétés des couches minces déposées par DBD alimentées par Ar/HMDSO/O2, Ar/PMDSO (pentaméthyldisiloxane)/O2 et Ar/TMDSO (tetraméthyldisiloxane)/O2, avec différentes proportions de l'oxygène, ont été confrontées aux analyses, par GC-MS, des gaz sortant du réacteur. Nous avons trouvé que l'ajout d'O2 au gaz d'alimentation n'améliore pas l'activation du précurseur organosilicié, même s'il augmente la puissance injectée. En revanche il influence fortement la composition chimique des dépôts et favorise une forte réduction de la concentration des sous-produits dans le gaz sortant du réacteur. Sans ajout de l'O2, des couches minces obtenues contiennent beaucoup de carbone , avec rétention de la structure du précurseur de départ. En réduisant le nombre de -CH3 dans le précurseur (HMDSO>PMDSO>TMDSO), le nombre et l'abondance des sous-produits détectés dans le gaz sortant du réacteur diminuent fortement. Il semblerait que les unités de répétition diméthylsiloxane et hydrométhylsiloxane jouent un rôle important dans l'oligomérisation des trois précurseurs. Différents mécanismes d'activation, ainsi que différents procédés de formation des groupes Si-OH dans les dépôts, ont été proposés pour les trois précurseurs.
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Lovascio, Sara. "Cold Plasma deposition of organosilicon films with different monomers in a dielectric-barrier discharge." Phd thesis, Paris 6, 2010. http://www.theses.fr/2010PA066069.
Full textAbstract:
Cette thèse porte sur une étude fondamentale sur le dépôt des couches minces d’organosiliciés par des Décharges à Barrière Diélectrique (DBD), un procédé très intéressant pour l’application aux textiles. La plupart des dépôts des couches d’oxyde de silicium sont déposées à partir du précurseur hexaméthyle silixone (HMDSO). De plus très peu d’études sont consacrées aux mécanismes de dépôt des couches à la pression atmosphérique. Dans cette étude les propriétés des couches minces déposées par DBD alimentées par Ar/HMDSO/O2, Ar/PMDSO (pentaméthyldisiloxane)/O2 et Ar/TMDSO (tetraméthyldisiloxane)/O2, avec différentes proportions de l’oxygène, ont été confrontées aux analyses, par GC-MS, des gaz sortant du réacteur. Nous avons trouvé que l’ajout d’O2 au gaz d’alimentation n’améliore pas l’activation du précurseur organosilicié, même s’il augmente la puissance injectée. En revanche il influence fortement la composition chimique des dépôts et favorise une forte réduction de la concentration des sous-produits dans le gaz sortant du réacteur. Sans ajout de l’O2, des couches minces obtenues contiennent beaucoup de carbone , avec rétention de la structure du précurseur de départ. En réduisant le nombre de –CH3 dans le précurseur (HMDSO>PMDSO>TMDSO), le nombre et l’abondance des sous-produits détectés dans le gaz sortant du réacteur diminuent fortement. Il semblerait que les unités de répétition diméthylsiloxane et hydrométhylsiloxane jouent un rôle important dans l’oligomérisation des trois précurseurs. Différents mécanismes d’activation, ainsi que différents procédés de formation des groupes Si-OH dans les dépôts, ont été proposés pour les trois précurseurs.
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BALTAZAR, Daniela Rubio. "Funcionalização do pericárdio bovino por plasma frio e análise de seu potencial como um biomaterial." Universidade Federal do Triângulo Mineiro, 2018. http://bdtd.uftm.edu.br/handle/tede/605.
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O colágeno é a proteína mais abundante em mamíferos, sendo o tipo I a forma
prevalente. Essa proteína possui propriedades interessantes, como baixa
imunogenicidade e toxicidade, biocompatibilidade, além de promover o
reconhecimento, adesão e diferenciação celular através de sequências RGD
(arginina-glicina-aspartato). Por isso, o colágeno é utilizado na composição de
diversos biomateriais. Contudo, após a implantação in vivo, a degradação do material
por colagenases endógenas pode ocorrer rapidamente, limitando sua utilização. A
funcionalização com plasma frio pode superar essa limitação, sendo capaz de
adicionar uniformemente grupos funcionais na superfície de materiais e ser modulada
para preservar ou alterar de maneira seletiva as propriedades do material. Este estudo
buscou funcionalizar o pericárdio bovino (PB) – composto principalmente por colágeno
tipo I – utilizando plasma frio a fim de obter um novo biomaterial. Para isso, amostras
de PB foram tratadas com plasma de argônio e CO2 a 2,45GHz e 500 W em um
intervalo tempo dede 0s (PBCT) a 240s (PB240) com incrementos de 30s. As
amostras foram analisadas por espectroscopia de infravermelho e a validação da
análise foi realizada através de modelagem molecular computacional. O material foi
caracterizado por microscopia óptica e eletrônica de varredura, ângulo de contato e
capacidade higroscópica. A biocompatibilidade do PB tratado foi verificada pela
implantação do material na camada subcutânea de camundongos Balb/c durante 3, 7
15 e 30 dias. Os resultados mostraram que as modificações causadas pelo tratamento
com plasma foram tempo dependente. Após 120s de tratamento (PB120) houve a
adição de grupos éster na forma de ligações crosslink sem alterações à estrutura
proteica. Entretanto, após 150s foi observado o início de um processo de etching e
degradação do colágeno, acentuado aos 240s. Além disso, o tratamento provocou um
aumento na hidrofobicidade da superfície do material. A implantação subcutânea
mostrou que não houve perda na biocompatibilidade do nos grupos tratados quando
comparado ao controle. Dessa forma, verificou-se que o tratamento com plasma pode
ser modulado para modificar o colágeno sem que haja perdas em suas propriedades
de interesse. Novos estudos são necessários para a adequação da funcionalização
com plasma, direcionando-a para modificações desejadas e aplicações específicas
do biomaterial.Collagen is the most commonly found protein in mammals and Type I is its most prevalent type. This protein shows interesting properties as low immunogenicity and toxicity, biocompatibility, besides the ability to promote cell recognition, differentiation and induce cell attachment through RGD (arginine-glycine-aspartate) sequences. Due to these characteristics, collagen is used in many biomaterials. However, after in vivo implantation, the degradation of the material by endogenous collagenases can occur too soon, impairing its application. Cold plasma functionalization can overcome this limitation; it is able to add evenly new functional groups on materials’ surfaces and can be tailored to preserve or alter selectively the bulk properties of the material. Therefore, this study aimed the functionalization of bovine pericardium (PB) – material composed of collagen type I – using cold plasma in order to obtain a new biomaterial. PB was treated with argon (Ar) and carbon dioxide (CO2), microwave power source 2.45Hz, 500 W. The treatment was carried out from 0 (PBCT) up to 240s (PB240), with a 30s increment. The samples were analysed by FTIR-ATR and the analysis validation was done through computing molecular modelling. The material was characterized by optical microscopy, SEM, contact angle and swelling. PB biocompatibility was assessed through subcutaneous implantation of the material in mice Balb/c for 3, 7, 15 and 30 days. The results indicated the changes caused by plasma treatment were time-dependent. By 120s of treatment (PB120) ester groups were added in the material, forming crosslink bonds without modification within the protein structure while 150s of treatment caused the beginning of an etching process and collagen degradation, which was more distinct at 240s; there was also an increase in the hydrophobicity on the surface of the treated material. The subcutaneous implantation test showed there wasn’t biocompatibility loss of treated PB when compared to control. Therefore, it was verified that plasma treatment can be tailored to modify collagen without impairing its properties of interest. New studies are necessary to suit plasma functionalization according the desired modifications and specific applications of the biomaterial.
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior
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Stekke, Jordan. "Contribution au perfectionnement de transformateurs pièzoélectriques dédiés à la génération de plasma froid pour applications biomédicales." Thesis, Toulouse, INPT, 2020. http://www.theses.fr/2020INPT0065.
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Face à l’évolution de notre compréhension des plasmas froids, leur spectre d’exploitation n’a cessé de croître durant ces dernières décennies. Même si dans le domaine biomédical, l'intérêt s'est aujourd'hui étendu à applications diverses telles que la thérapie cellulaire, le soin des plaies, la chirurgie dentaire ou le traitement cornéen, la désinfection par plasma froid reste un sujet d’étude prépondérant dans le domaine. De nombreux générateurs plasma ont été développés dans le but de répondre aux exigences de désinfection des outils thermosensibles ou chimiosensibles. De nombreuses difficultés telles qu'un niveau de désinfection élevé, une durée de traitement minimale, un rapport de forme ou une géométrie complexe des outils doivent être prises en compte. Leur caractéristique commune est la nécessité d'une source de haute tension en entrée. Elle se justifie par l’obligation d'atteindre la valeur de tension de claquage du gaz de plusieurs kVolts. Dans certaines applications, cette source de haute tension peut représenter un problème de sécurité pour les personnes (choc électrique) et les appareils électriques (interférences électromagnétiques)With the evolution of our understanding of cold plasmas, their spectrum of exploitation has continued to increase over the past decades. Even if in the biomedical field, the interest has now extended to various applications such as cell therapy, wound care, dental surgery or corneal treatment, cold plasma disinfection remains a major subject of study in this field. Many plasma generators have been developed to meet the disinfection requirements of heat-sensitive or chemosensitive tools. Many difficulties such as a high level of disinfection, a minimum treatment time, a shape ratio or complex tool geometry must be taken into account. Their common feature is the need for a high voltage input source. It is justified by the obligation to reach the gas breakdown voltage value of several kVolts. In some applications, this high voltage source can be a safety problem for people (electric shock) and electrical equipment (electromagnetic interference)
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Fogleman, Myles. "Cold X-ray Effects on Satellite Solar Panels in Orbit." VCU Scholars Compass, 2019. https://scholarscompass.vcu.edu/etd/6065.
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An exo-atmospheric nuclear detonation releases up to 80 percent of its’ energy as X-rays. Satellite’s solar cells and their protective coatings are vulnerable to low energy X-ray radiation. Cold X-rays (~1-1.5 keV) are absorbed close to the surface of materials causing the blow-off and rapid formation of Warm Dense Plasmas (WDPs), particularly in a gap between the unshielded active elements of solar cells. To understand how WDPs are created, it is necessary to investigate the power density distribution produced by cold X-rays for typical solar panel surface materials. The Monte Carlo stepping model implemented in the GEANT4 software toolkit is utilized to determine the power density created by cold X-rays in a multi-layered target composed of a layer of an active cell shielded by layers of cover glass and anti-reflective coating. The power density generated by cold X-rays in the unshielded semiconductor layer at different incidence angles is also investigated in order to account for different orientations of the satellite’s solar panels with respect to the point of nuclear detonation. The flux spectrum of X-rays originating from a nuclear blast is described by the Planck's blackbody function with the temperature from 0.1 keV to 10 keV. The secondary radiation (photo-electrons, fluorescence photons, Auger- and Compton-electrons) resulting from absorption and scattering of primary X-rays is taken into account in the redistribution of energy deposition within slabs. The profiles of power density within the slab system produced by primary cold X-rays, secondary photons and electrons are calculated as a function of depth. The discontinuity in power density profiles is observed at the interfaces of slabs due to discrete changes in stopping power between slab materials. The power density is found to be higher in slab materials with higher mass density. The power density profiles are then used in the atomistic Momentum Scaling Model (MSM) coupled with the Molecular Dynamics (MD) method (MSM-MD) to predict the spatiotemporal evolution of WDP in vacuum. The spatial and temporal distribution of density and temperature fields of expanding WDP is evaluated from the MSM-MD simulations. These modeling results provide insights into the underlining physics of the formation and spatiotemporal evolution of WDPs induced by cold X-rays.
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Liu, Bo. "Non-thermal atmospheric pressure plasma interacting with water for biological applications." Thesis, Université Paris-Saclay (ComUE), 2019. http://www.theses.fr/2019SACLX049/document.
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Les plasmas froids produits par les décharges électriques sont des gaz faiblement ionisés, ce qui maintient la température du gaz à une température proche de la température ambiante, contrairement à la température de l'électron qui peut atteindre plusieurs électron-volts. Les applications des plasmas froids en médecine et en agriculture sont des nouveaux domaines de recherche multidisciplinaires basés sur les interactions de ces plasmas avec des organismes vivants. Le champ électrique ainsi que les espèces réactives de l’oxygène et de l'azote peuvent inactiver les bactéries, stimuler la régénération de la peau (dermatologie), la réduction tumorale (oncologie) et la germination des graines (agriculture). Ces nouveaux domaines de recherche, basé sur la chimie produite par l’interaction plasma-liquide est très prometteur et se développe rapidement. L’objectif de ce travail est d’étudier les interactions entre les plasmas froids et l’eau pour les applications biologiques, d’une part la promotion de la germination des graines au moyen d’une décharge à barrière diélectrique (DBD) et, d’autre part, l’effet ex vivo d’un traitement par jet de plasma froid sur la peau.Ce manuscrit est divisé en cinq chapitres: i) On présente tout d'abord une revue de la littérature présentant l'état de l’art concernant l'interaction plasma-liquide et les principales avancées en matière d'applications des plasmas froids à la germination des semences. Ii) Deuxièmement, les dispisitifs expérimentaux sont décrits, en particulier la fabrication de réacteurs à plasma utilisant l’impression 3D. Iii) Ensuite, la production d'espèces réactives gazeuses et aqueuses formées par des plasmas de type DBD a été mesurée quantitativement et l'interaction plasma-liquide a été analysée. Iv) Puis, plusieurs variétés de graines ont été sélectionnées pour évaluer l’effet un traitement par plasma DBD ; l'étude des mécanismes de promotion de la germination du plasma a été spécifiquement étudiée en traitant les graines de soja vert dans différentes conditions de décharge, dans différents milieux, avec un champ électrique seul et dans différentes conditions de cultures ou de niveau d'hydratation des graines.v) Enfin, l'imagerie paramétrique de Muller (MPI) a été appliquée pour la modification de la peau de souris ex vivo traitées par un plasma à jet d'héliumNon-Thermal-Plasmas (NTP) produced by electric discharges are weakly ionized gases, which keeps the gas temperature at near room temperature contrary to the electron temperature which can reach several electron-Volts. Applications of NTP to medicine and agriculture are new multidisciplinary research fields based on interactions of the Non-Thermal-Plasmas with living organisms. Electric field as well as Reactive Oxygen and Nitrogen Species produced by NTP may inactivate bacteria, stimulate skin regeneration (dermatology), tumor reduction (oncology) and seeds germination (agriculture). These new fields of research are based on the plasma-liquid chemistry. The objective of this work is to study the NTP interacting with water for biological applications including on one hand, the promotion of the germination of seeds using a Dielectric Barrier Discharge (DBD) and on the other hand, the effect of a plasma jet treatment ex vivo on skinThis manuscript is divided in five chapters: i) First a literature review is presented showing the state of the art of the plasma-liquid interaction, and the main advances of the application of non thermal plasmas to seed germination. Ii) Second, experimental set ups are described, in particular the manufacturing of plasma reactors using 3D printing. Iii) then , the production of gaseous and aqueous reactive species formed by DBD plasmas was measured quantitatively and plasma-liquid interaction was analyzed. Iv) Next, different varieties of seeds were selected to evaluate the effect of a DBD plasma treatment and the study of the mechanisms of plasma germination promotion was specifically investigated by treating mung bean seeds in different discharge conditions, in different mediums, in electric field alone and in different hydration levels of seeds.v) Finally, Muller parametric imaging (MPI) was applied to study the modification of ex vivo mice skin treated by a helium jet plasma
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Williams, David. "The use of cold atmospheric plasma (CAP) treatment for the structural adhesive bonding of metals." Thesis, University of Surrey, 2018. http://epubs.surrey.ac.uk/845705/.
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Adhesive bonding for structural applications has many advantages such as reducing the weight of vehicles and providing efficient stress transfer across joined materials. The largest asset of adhesive bonding is that they can join dissimilar materials. To achieve the highest joint strength possible when using metals, however, the metal surfaces have to be pre-treated. This can be done in a variety of ways, such as grit blasting or chemical etching. Chemically etching the surface produces the highest strength joints, but has many drawbacks. The first of which is that each metal used requires a different treatment chemistry. This reduces the materials available for selection as a result of increased pre-treatment complexity. The current work focusses on stainless steel and titanium alloy. The lap shear bond strength for both metals increased significantly after a cold atmospheric plasma (CAP) treatment and was in line with the chemical etching processes. The durability of both metals demonstrated that the plasma treatment increases the performance. For stainless steel the durability is similar to the chemical etch process. For titanium the durability performance is increased, but does not reach the level of the chemical treatment process. A combination of surface science techniques has revealed that there are three mechanisms which lead to an increased bond strength. These are: a reduction in hydrocarbon contamination, shown using X-ray photoelectron spectroscopy (XPS) and time of flight\,-\,secondary ion mass spectrometry (ToF-SIMS). The growth of the surface oxide layer, analysed using an XPS sputter depth profile, and functionalisation of the oxide layer, which has been probed using ToF-SIMS, both lead to an increase in lap shear bond strength. The feasibility of the process rests on two factors. The first is achieving equivalent mechanical properties, the second factor is the energy, resources and time required for a given treatment. The first has been satisfied in this work, the second has been investigated using a life cycle analysis approach which found that plasma treatment had a higher impact on the environment when compared to oxalic acid etching. but this assumed that the acid is 100\% efficient, which is far from the case. When simulated in a `real world' scenario, there is nearly parity between the two treatments Based on the data presented in this work, including analysis of the process life cycle, CAP has the potential as a first multi material pre-treatment for structural adhesive bonding.
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Köritzer, Julia [Verfasser], and Gregor [Akademischer Betreuer] Morfill. "Biophysical effects of cold atmopheric plasma on glial tumor cells / Julia Köritzer. Betreuer: Gregor Morfill." München : Universitätsbibliothek der Ludwig-Maximilians-Universität, 2013. http://d-nb.info/1043906576/34.
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Lo, Yi-Ping. "A new individual-based modelling framework for bacterial biofilm growth applied to cold plasma treatment." Thesis, Loughborough University, 2013. https://dspace.lboro.ac.uk/2134/12311.
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Biofilms are colonies of bacteria attached to the surface at a solid-fluid interface. Bacteria in biofilm produce exopolysaccharides (EPS) that form a gel-like matrix in which the bacteria are embedded. Biofilms have numerous consequences in industrial and medical settings, both positive (bioreactors, digestion) and negative (blocking, as corrosive damage of materials/devices, food contamination, clinical infection). The use of antibiotics or mechanical clearing can be effective at removing biofilms, but such treatments are not always effective or appropriate in all situations. Recently, non-thermal atmospheric plasma treatments have been proposed as an alternative (or complementary) form of treatment, that can target sites of infection with minimal damage to the surroundings (e.g. host cells in a clinical setting). These plasmas generate a multitude of chemical species, most of which are very short lived, that can infiltrate and diffuse into the biofilm killing the bacteria within. The aim of this thesis is to develop a multi-dimensional mathematical model to investigate the effect of a non- thermal plasma on biofilms in time and space and to identify key factors that determine effectiveness of the treatment. Most of the chemical products of cold plasmas are too short lived, or too reactive, to be effective in killing the biofilms, it is the longer live species, e.g. ozone, hydrogen peroxide, acid species, that penetrated the biofilm and do the most damage. However, the EPS in biofilms is an effective barrier against ozone and hydrogen peroxide. No published biofilm model combines multi-dimensional growth with a detailed description of EPS production, hence a new mathematical model is developed and applied to simulating plasma treatment. The thesis is split broadly into two parts. The first part presents a new biofilm model framework that simulates growth in response to any number of substrates (e.g. nutrient, oxygen). The model combines an Individual based model (IbM) description of bacteria (individuals or clusters) and substrates are described as a continuum. Novel features of the framework are the assumption that EPS forms a continuum over the domain and the explicit consideration of cellular energy (ATP). Simulations of this model demonstrate the contrast between biofilm grown with topical nutrient sources (forming irregular, bumpy biofilm) and basal nutrient source with topical oxygen such as biofilm grown on agar (forming regular spatially uniform biofilms). The former is in broad agreement with experiments whilst the latter, to our knowledge, has been the subject of very little experimental study. The second part extends the modelling framework to consider the effect of the plasma species. The simulations demonstrate that penetration is a key factor in their effectiveness, for which EPS plays a key role in preventing spread within and beyond the plasma treated zone. The simulations provide estimates of the timescale of equilibration of the main plasma species, predict the effect of combining these species and demonstrate how the constituents of the biofilm can change following treatment. A number of recommended suggestions for future theoretical and experimental study are discussed in the conclusions.
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Wang, Peiyu. "Strategy and molecular mechanism study of cold atmospheric plasma applications in oncotherapy, virucide and nanotechnology." Thesis, Queensland University of Technology, 2021. https://eprints.qut.edu.au/214016/1/Peiyu_Wang_Thesis.pdf.
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This thesis is the study of cold atmospheric plasma (CAP) applications in cancer, anti-viral treatments, and nano-biotechnology. The optimal treatment strategy, potential molecular mechanism and methods to increase selectivity and efficiency of plasma treatment were investigated for each application. In the near future, CAP or plasma activated medium (PAM) would likely become a widely used, high-efficiency and targeted clinical therapeutic tool.
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Kopytko, Nathalie. "Valorisation chimique du méthane par plasma froid microondés." Vandoeuvre-les-Nancy, INPL, 1993. http://www.theses.fr/1993INPL100N.
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Le but de ce travail de thèse était d'étudier les réactions chimiques du méthane excité dans une décharge micro-ondes, a basse pression, de manière à former un plasma froid. Nous nous sommes principalement intéressés aux produits obtenus par la réaction chimique du méthane, en particulier les hydrocarbures en c#2. Nous avons étudié d'abord le plasma de méthane pur. Après la mise au point de l'installation, nous avons effectué une étude paramétrique (influence du temps de passage des gaz dans le réacteur de la puissance micro-ondes incidente, du débit et de la pression de méthane). Nous avons ensuite examiné dans quelle mesure les mécanismes réactionnels simplifiés proposés dans la littérature pouvaient correspondre à nos résultats expérimentaux. Nous avons ensuite brièvement étudié les plasmas méthane-hydrogène, méthane-oxygène et méthane-dioxyde de carbone. Nous avons comparé nos résultats avec ceux obtenus par une autre méthode plasma de transformation du méthane ainsi qu'avec ceux résultant d'autres procédés de valorisation directe du méthane actuellement à l'étude. Nous avons déterminé quelles étaient les directions de recherche à envisager pour une suite de ce travail
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Magi, Linda. "Caratterizzazione e ottimizzazione di sorgenti plasma di non equilibrio a pressione atmosferica (CAP) per applicazioni biomedicali." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2018.
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Il plasma freddo di non equilibrio a pressione atmosferica (Cold Atmospheric pressure Plasma,CAP) è in grado di produrre un blend di specie chimiche in grado di conferirgli proprietà sia antibatteriche sia antitumorali. La tecnologia CAP quindi trova un potenziale impiego sia in ambito dentale sia in campo oncologico. Nel presente lavoro di tesi sperimentale è stato condotto uno studio di ottimizzazione di una sorgente Dielectric Barrier Discharge – Jet (DBD-Jet) per applicazioni dentali col fine di massimizzare le specie reattive prodotte in liquido e verificare il potere battericida mediante prove biologiche su sospensione liquida. I risultati ottenuti dimostrano come le specie reattive prodotte nel liquido siano in grado di determinare inattivazione totale della crescita batterica.
Successivamente, sono stati analizzati gli effetti antitumorali di un trattamento plasma assistito indiretto su una linea cellulare leucemica mediante un mezzo di coltura attivato plasma (PAM). Questa ampia attività di ricerca in campo oncologico è stata finanziata da un progetto SIR e prevede la collaborazione di differenti gruppi di ricerca. In questo progetto è stato condotto uno studio di sensibilità per una sorgente Plasma Gun al fine di verificare quanto ogni variabile di natura sperimentale possa influire sulla produzione di specie reattive in liquido. I risultati riportano che nessun parametro analizzato ha influenza sulla produzione di specie reattive nel PAM. La valutazione degli effetti indotti sulle cellule tumorali dal mezzo di coltura attivato plasma è stata effettuata mediante analisi cito-tossicologiche che evidenziano il livello di necrosi, apoptosi e vitalità cellulare a 24h e 48h. I risultati evidenziano che le specie reattive generate nel liquido inducono morte cellulare per via apoptotica. Infine sono stati effettuati test ex vivo su cellule espiantate da pazienti sani e malati col fine di valutare la selettività di un trattamento con PAM sulle cellule leucemiche.
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Morillo, candas Ana. "Investigation of fundamental mechanisms of CO2 plasmas." Thesis, Université Paris-Saclay (ComUE), 2019. http://www.theses.fr/2019SACLX091.
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Les plasmas froids constituent l’une des voies les plus prometteuses pour recycler efficacement le CO2 en carburants de synthèse ou en molécules de base pour la chimie organique « verte ». Pour obtenir des rendements énergétiques satisfaisants, il est nécessaire de bien contrôler les transferts d’énergie vibrationnelles dans la molécule de CO2 considérés bénéfiques pour la dissociation, mais aussi l’énergie transférée aux états électroniquement excités ainsi que les processus de recombinaison de O avec CO. Toutefois, en dépit d’une littérature conséquente sur les lasers CO2 et les plasmas de rentrée atmosphérique, de nombreux processus essentiels à la description des plasmas de CO2 sont encore très mal compris. Cette thèse a donc pour objectif de réaliser des mesures dans des conditions suffisamment bien contrôlées pour identifier et étudier certains de ces mécanismes. Pour y parvenir Deux types de sources de plasma, une décharge "luminescente" DC et une décharge radiofréquence (RF) ont été étudiées à basse pression (27-1000 Pa) ce qui ralentit les temps caractéristiques des différents processus. Ces sources plasmas ont été étudiées à l’aide de techniques optiques de pointe complémentaires afin d’obtenir dans un même système, tous les paramètres pertinents pour une description complète du plasma. Ainsi les densités et températures vibrationelles de CO2 et CO ont été mesurées par spectroscopie d’absorption infrarouge (FTIR), la densité et les fréquences de perte des atomes d’oxygène par TALIF haute résolution, actinométrie et CRDS, alors que des mesures d’échanges isotopiques ont donné des informations notamment sur le rôle de O(1D). La plupart de ces techniques permettent également de déterminer la température du gaz illustrant simultanément la précision et la cohérence des mesures obtenues par différentes techniques.Toutes ces mesures ont pu être réalisées in situ et résolues en temps pour suivre l’évolution de ces paramètres durant et après des pulses du plasma, que ce soit en DC glow ou en RF. Outre la validation de modèles cinétiques développés à l’IST Lisbonne, toutes ces données ont permis d’obtenir de nombreux résultats parmi lesquels l’identification de la meilleure section efficace de dissociation du CO2 par impact électronique, ou la quantification de la désexcitation vibrationelle du CO2 par les atomes d’oxygène.Un aspect important du travail a également porté sur l’influence des surfaces sur le plasma. Les processus de perte d'atomes de O dominés par la recombinaison en surface, se sont avérés dépendre de la température des atomes près de la surface. Il a aussi été montré qu’un plasma de CO2 peut passiver la surface de SiO2 diminuant la probabilité de recombinaison des atomes d’oxygène aux parois, et la rendant identique sous exposition au plasma et en post-décharge contrairement a ce qui est observé en plasma de O2. Une comparaison préliminaire avec un modèle de surface Monte-Carlo donne un bon éclairage sur les mécanismes de surface impliqués. En utilisant des fibres de SiO2 de grandes surfaces spécifiques, la formation de CO2 en surface a été mise en évidence ce qui limite l'efficacité de dissociation. Au contraire des surfaces à base de carbone ont permis une augmentation importante de la conversion du CO2 en piégeant les atomes d'oxygène. Ceci démontre le rôle essentiel que des surfaces catalytiques pourraient jouer dans l’efficacité de conversion du CO2 et l'importance de contrôler la réactivité des atomes d'oxygène.L’ensemble de ces résultats offre une vision beaucoup plus détaillée de la cinétique des plasmas de CO2. Il s’agit donc d’un travail utile non seulement pour développer de nouveaux procédés efficaces de conversion du CO2 avec ou sans catalyseurs, mais également dans des domaines tels que les traitements de surfaces utilisant des plasmas contenant du CO2 ou les problèmes d’entrée atmosphériques par exempleThe use of non thermal plasmas is one of the most promising paths to efficiently recycle CO2 into more complex organic molecules, such as energy-dense hydrocarbon fuels, and it is compatible with the use of intermittent renewable energy sources. To obtain satisfactory energy yields, it is necessary to properly control the energy transfer processes, including the vibrational energy of the CO2 believed to be beneficial for the CO2 conversion, or the energy stored in electronically excited species. Recombination processes producing CO2 from the dissociation products (the so-called back reaction) must also be prevented. However, despite the extensive literature in the fields of CO2 lasers, atmospheric entry plasmas or CO2 conversion, many of the basic mechanisms essential for the description of CO2 plasmas are still very poorly understood. The objective of this thesis is therefore to perform experiments under sufficiently well controlled conditions to identify and study some of these fundamental mechanisms. Two types of plasma sources, a DC "glow" discharge and a radio frequency (RF) discharge were studied at low pressures (27-1000 Pa) to slow down characteristic times of various processes. Advanced optical diagnostic techniques were used in situ and time-resolved to obtain all the relevant parameters for a complete description of the plasma. The densities and vibrational temperatures of CO2 and CO were measured by infrared absorption spectroscopy (FTIR), giving also insight in back reaction mechanisms. The density and loss frequencies of oxygen atoms were obtained with High Resolution Two photon Absorption Laser Induced Fluorescence (HR-TALIF), actinometry and Cavity Ring Down Spectroscopy (CRDS), while isotopic exchange measurements provided information on the role of O(1D). Most of these techniques were also used to determine the gas temperature showing simultaneously the consistency and accuracy of the different techniques.The experimental results made possible, for instance, the identification of the most accurate cross section for CO2 dissociation by electronic impact or the quantification of the vibratory de-excitation of CO2 by oxygen atoms. The obtained data were also used to validate a 0D kinetic model developed at IST Lisbon, which allowed the validation of the rates for vibration-vibration or vibration-translation energy transfer processes for the low vibrational levels of CO2.Another important part of the work focused on the role of the surfaces on the CO2 plasma kinetics. The O atoms loss processes were found to be dominated by surface recombination, dependent on the temperature of the O atoms near the surface, similarly to a pure O2 plasma. However, it was found that CO2 plasma can passivate SiO2 surfaces, reducing the recombination probability of oxygen atoms at the walls, and making it identical under plasma exposure and in post-discharge, unlike what is observed in O2 plasma. A preliminary comparison with a Monte-Carlo surface model, provides a valuable insight in the surface mechanisms involved. Large specific SiO2 surfaces were found to induce CO2 formation in the surface under high O atom flux regimes, limiting dissociation efficiency, whereas the use of carbon-based surfaces showed an enormous potential to use the oxygen atoms to enhance the final CO2 conversion, demonstrating the key role of the surfaces in the efficiency of the CO2 conversion and the importance of a proper handling of the oxygen atoms. These results are therefore very valuable to understand which materials would be relevant to be used as catalysts to improve CO2 conversion efficiency by plasma.The thesis provides a detailed view on the fundamental mechanisms controlling the kinetics of CO2 plasmas, and the results presented are therefore useful not only for developing more efficient CO2 conversion processes, with or without catalysts, but they are also relevant in fields such as surface treatment using O2/CO2-containing plasmas
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Amadori, Raul. "Trattamenti sanificanti a freddo: ozono e plasma freddo a confronto." Bachelor's thesis, Alma Mater Studiorum - Università di Bologna, 2021.
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Da parte dei consumatori si sta assistendo ad un aumento della domanda relativa agli alimenti minimamente trasformati ed alla produzione di alimenti sicuri e di alta qualità.
Di conseguenza, le tecnologie di trasformazione non termica possono essere dei metodi alternativi per la conservazione di alimenti e per ridurre gli aspetti negativi sul profilo nutrizionale.
Tra queste, l’ozono e il plasma freddo sono classificate tecnologie non termiche in via di sviluppo.
Essendo tecnologie non termiche non si basano sulle alte temperature, di conseguenza non portano alterazioni significative sulla qualità del prodotto e non portano alla creazione di sostanze dannose per la salute umana; si ottiene un giusto compromesso tra qualità e sicurezza microbica.
Inoltre, rispetto agli altri metodi tradizionali non lasciano residui nell’ambiente e per tanto non causano inquinamento; per questo motivo possono andare a sostituire i normali disinfettanti.
Secondo gli studi presenti in letteratura, la loro applicazione si può estendere su tutti i tipi di prodotti e le loro azioni antimicrobiche sono efficaci sulla maggior parte dei microrganismi patogeni dell’alimentazione.
Il loro effetto antimicrobico si basa sull’ossidazione, quindi non hanno bisogno di reagenti specifici ma è bene ricordare che se il trattamento non viene eseguito in maniera adeguata, esso può portare danni al prodotto abbassando qualità.
Entrambe sono classificate come tecnologie ad ostacoli, infatti sono numerosi gli studi in cui l’ozono e il plasma freddo vengono combinati con altre tecniche per aumentare l’efficacia antimicrobica mantenendo inalterata la qualità dell’alimento. Dall’esame della letteratura aggiornata possiamo affermare che entrambe le tecnologie si sono dimostrate ottime soluzioni alternative per la decontaminazione microbica e possono rappresentare una valida alternativa ai metodi tradizionali per soddisfare la domanda globale di apporto nutrizionale e della richiesta di alimenti di alta qualità.
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Bafoil, Maxime. "Stimulation de la germination des graines et de la croissance des plantes par plasmas froids à la pression atmosphérique." Thesis, Toulouse 3, 2020. http://www.theses.fr/2020TOU30208.
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Ces travaux s'inscrivent à la convergence des domaines de la physique des plasmas et de la biologie végétale. L'objectif de cette thèse est de contribuer à apporter des réponses quant aux mécanismes impliqués dans les effets des plasmas froids à pression atmosphérique sur la germination et le développement des plantes. La plante modèle en biologie végétale Arabidopsis thaliana est utilisée ; en considérant le génotype de référence Col-0 et plusieurs de ses mutants (gl2 et gpat5) afin de mieux mettre en évidence l'effet du plasma notamment sur les stress osmotiques et salins. Pour le traitement direct des graines afin de favoriser la germination, les plasmas d'air sont utilisés. Le traitement indirect, servant à la stimulation de la croissance, utilise l'eau activée par plasma (PAW) grâce aux jets de plasma d'hélium. Les résultats montrent un effet positif du traitement au plasma d'air généré par un dispositif de décharge à barrière diélectrique sur électrode flottante (FE-DBD) et également un dispositif corona dans l'air ambiant. Ces traitements directs permettent une augmentation du taux de germination mais surtout une augmentation de la vitesse de germination. Une analyse de la perméabilité des graines a mis en évidence un changement à la surface des graines dû à un effet physique du plasma sur la surface. L'analyse des résidus de surface montre un changement en composition lipidique. Cela étant fortement corrélé avec la germination, ces résultats permettent la mise en évidence de piste de compréhension des effets des plasmas sur la germination des graines. Dans une seconde partie, le traitement indirect des plantes par le PAW a pour effet une augmentation de la vitesse de croissance. Le plasma créant un nombre certains d'espèces réactive de l'oxygène et de l'azote (notamment des nitrates et des nitrites) agit comme un engrais stimulant la croissance des plantesThis work is part of the convergence of the fields of plasma physics and plant biology. The objective of this thesis is to contribute answers to the mechanisms involved in the effects of cold plasmas at atmospheric pressure on the germination and development of plants. The plant model in plant biology Arabidopsis thaliana is used; by considering the reference genotype Col-0 and several of its mutants (gl2 and gpat5) in order to better highlight the effect of plasma, in particular on osmotic and saline stresses. For the direct treatment of seeds to promote germination, air plasmas are used. Indirect treatment for growth stimulation uses plasma-activated water (PAW) thanks to helium plasma jets. The results show a positive effect of the plasma treatment of air generated by a dielectric barrier discharge device on a floating electrode (FE-DBD) and also a corona device in ambient air. These direct treatments allow an increase in the germination rate but above all an increase in the speed of germination. Analysis of the seed permeability revealed a change in the seed surface due to a physical effect of the plasma on the surface. Analysis of the surface residues shows a change in lipid composition. This being strongly correlated with germination; these results allow the identification of an understanding track of the effects of plasmas on the germination of seeds. In a second part, the indirect treatment of plants with PAW has the effect of increasing the growth rate. The plasma creating a certain number of reactive species of oxygen and nitrogen (in particular nitrates and nitrites) acts as a fertilizer stimulating the growth of plants
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Boxhammer, Veronika [Verfasser], and Gregor [Akademischer Betreuer] Morfill. "Developmant of a safe therapeutic window for cold atmospheric plasma treatments / Veronika Boxhammer. Betreuer: Gregor Morfill." München : Universitätsbibliothek der Ludwig-Maximilians-Universität, 2014. http://d-nb.info/1065610483/34.
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Magalhães, Washington Luiz Esteves. "Deposição de filmes protetores sobre madeira pela técnica do plasma frio." Universidade de São Paulo, 2002. http://www.teses.usp.br/teses/disponiveis/88/88131/tde-12032014-202931/.
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A madeira maciça é um compósito polimérico natural que pode sofrer tratamentos para atender a diversas especificações técnicas. Uma característica da madeira é a sua higroscopicidade. A madeira úmida é vulnerável ao ataque de térmitas e fungos, além de perder estabilidade dimensional. Os tratamentos mais usados são a impregnação e/ou o revestimento com tintas e vernizes. Uma técnica promissora para o revestimento de madeira maciça é o plasma frio ou descarga luminescente. Neste trabalho produziu-se plasmas frios através de descargas elétricas luminescentes em gases rarefeitos. Os precursores gasosos usados foram o etileno, acetileno, 1-buteno, e vapor de metil metacrilato e de acetato de vinila. A superfície de madeira maciça tratada por estes plasmas ficaram hidrofóbicas, sendo que os melhores resultados foram alcançados usando 1-buteno como gás precursor. Apesar do tratamento promover repelência à água, a superfície tratada continuou permeável ao vapor d\'água. Com o emprego de uma mistura gasosa formada por vapor de TEOS e O2, foi possível constatar a ineficiência da descarga luminescente capacitiva em revestir o interior de orifícios em madeira. A deposição de filmes finos a partir de plasmas de 1-buteno foi caracterizada, tendo apresentado propriedades distintas do polímero convencional. O filme depositado por plasma apresentou hidrofobicidade, resistência química, insolubilidade em solventes comuns, e resistência contra teste acelerado de intemperismo. A espectroscopia de infravermelho e a análise elementar também revelaram diferenças entre os filmes convencional e depositado por plasma. As reações químicas no plasma podem ser controladas através de ajustes na potência transferida ao reator, pressão da câmara, vazão dos gases, e tempo de exposição à descarga. Com o uso de plasmas menos energéticos é possível produzir filmes poliméricos com estruturas menos entrecruzadas. Duas técnicas distintas foram testadas neste trabalho: o plasma capacitivo e o jato de plasma. Ambas as técnicas são promissoras em função do baixo nível de vácuo necessário, baixas freqüências, pequeno consumo de energia, ausência de poluição e solventes, e o uso de reagentes disponíveis em escala industrial.Solid wood is a natural polymer composite that can be subjected to a wide variety of treatments to make it suitable for specific technical applications. The greatest disadvantage of solid wood is its hygroscopicity. Moist wood is vulnerable to attack by fungi and termites, and loses its dimensional stability. The most widely used treatments for solid wood are impregnation and coating with paint and varnish. A promising future technique for solid wood surface coating is a plasma treatment in a glow discharge. Cold plasmas were produced by electrical glow discharges in a gas medium at reduced pressure. The precursor gases used were ethylene, acetylene, 1-butene, and vapor of vinyl acetate. The treatment caused the solid softwood surface to become hydrophobic; 1-butene-plasma produced the best results. Although the surface plasma treatment resulted in water repellence, permeability to water vapor remained. Using a mixture of tetraethyl orthosilicate vapor (TEOS) and oxygen (O2) it was possible to investigate the inability of the glow discharge to coat the surface of wood orifices. Deposition of non-conventional polymeric thin films were observed on solid wood substrate after injecting a 1-butene-argon gas mixture into a glow discharge chamber. The deposited film showed water repellence, chemical resistance, insolubility in most common organic solvents and some protection against weathering. Infrared analyses revealed differences between conventional and plasma polymerized 1-butene. Plasma chemistry can be controlled by external conditions of plasma, such as input power, gas flow rate, pressure, and the time of exposure. Using low energetic plasmas the deposited film can be polymer like with a less crosslinked structure. Two different techniques - known capacitive coupled plasma and plasma jet - were tested in this study. Both these techniques appear promising in view of the low vacum level and low frequency, low power supply required, the lack of pollutants and solventes, and the use of industrial chemicals.
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Karderinis, Sideris. "Spectroscopic studies of radio-frequency plasmas." Thesis, University of Oxford, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.325952.
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Jiang, Xuewen. "Sustainable Methods for Cyanotoxin Treatment and Discovery of the Cyanophage." The Ohio State University, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=osu1492098348720028.
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Bakshi, Srinivasa R. "Plasma And Cold Sprayed Aluminum Carbon Nanotube Composites: Quantification Of Nanotube Distribution And Multi-Scale Mechanical Properties." FIU Digital Commons, 2009. http://digitalcommons.fiu.edu/etd/97.
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Carbon nanotubes (CNT) could serve as potential reinforcement for metal matrix composites for improved mechanical properties. However dispersion of carbon nanotubes (CNT) in the matrix has been a longstanding problem, since they tend to form clusters to minimize their surface area. The aim of this study was to use plasma and cold spraying techniques to synthesize CNT reinforced aluminum composite with improved dispersion and to quantify the degree of CNT dispersion as it influences the mechanical properties. Novel method of spray drying was used to disperse CNTs in Al-12 wt.% Si pre-alloyed powder, which was used as feedstock for plasma and cold spraying. A new method for quantification of CNT distribution was developed. Two parameters for CNT dispersion quantification, namely Dispersion parameter (DP) and Clustering Parameter (CP) have been proposed based on the image analysis and distance between the centers of CNTs. Nanomechanical properties were correlated with the dispersion of CNTs in the microstructure. Coating microstructure evolution has been discussed in terms of splat formation, deformation and damage of CNTs and CNT/matrix interface. Effect of Si and CNT content on the reaction at CNT/matrix interface was thermodynamically and kinetically studied. A pseudo phase diagram was computed which predicts the interfacial carbide for reaction between CNT and Al-Si alloy at processing temperature. Kinetic aspects showed that Al4C3 forms with Al-12 wt.% Si alloy while SiC forms with Al-23wt.% Si alloy. Mechanical properties at nano, micro and macro-scale were evaluated using nanoindentation and nanoscratch, microindentation and bulk tensile testing respectively. Nano and micro-scale mechanical properties (elastic modulus, hardness and yield strength) displayed improvement whereas macro-scale mechanical properties were poor. The inversion of the mechanical properties at different scale length was attributed to the porosity, CNT clustering, CNT-splat adhesion and Al4C3 formation at the CNT/matrix interface. The Dispersion parameter (DP) was more sensitive than Clustering parameter (CP) in measuring degree of CNT distribution in the matrix.
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Teixeira, Rafael Eduardo da Silva. "Targeting cancer with cold atmospheric plasma." Master's thesis, 2017. http://hdl.handle.net/10316/82236.
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Trabalho de Projeto do Mestrado Integrado em Medicina apresentado à Faculdade de MedicinaNos países desenvolvidos, o diagnóstico de cancro é cada vez mais comum. Numa era em que as atuais terapias no combate ao cancro não são isentas de riscos, uma nova terapia baseada em plasma, o quarto estado da matéria, captou a atenção da comunidade médica. O objetivo deste trabalho foi avaliar o efeito, a seletividade e os mecanismos de ação do plasma frio atmosférico (CAP) numa linha celular humana de retinoblastoma Y79. Desenvolvemos um dispositivo eletrónico capaz de gerar CAP, com ar, 2mm acima de uma suspensão de células Y79, em placas multipoços. O espectro de emissão do plasma (OES) foi obtido por um espectrómetro. Para testar a citotoxicidade e a seletividade do CAP, avaliou-se a atividade metabólica de células Y79 e fibroblastos humanos HFF1 tratados de forma semelhante. O protocolo de deteção de apoptose, a análise do potencial de membrana mitocondrial (MMP) e a microscopia óptica para avaliação da morfologia celular foram usados para esclarecer o tipo de morte celular. A coloração com iodeto de propídio e RNAse foi empregue para estudo do ciclo celular e avaliaram-se os efeitos genotóxicos através do ensaio cometa. As espécies reativas de oxigênio e nitrogênio (RS) e as defesas oxidativas foram quantificadas. Para explorar o efeito do campo elétrico sobre os canais de cálcio dependentes de voltagem, procedeu-se ao bloqueio farmacológico com verapamil. A sobrevivência celular foi avaliada pelo ensaio clonogénico. Finalmente, os efeitos antiangiogénicos foram quantificados pelo ensaio do anel aórtico. Após 60s de tratamento com CAP, a atividade metabólica das células de retinoblastoma sofreu uma redução superior a 50%, principalmente devido à apoptose, sem afetar a viabilidade das células HFF1. A diminuição da sobrevivência celular e a acumulação de células nas fases S e G2/M foram vistas sem terem sido detetadas quebras das cadeias de DNA. O OES revelou vários picos no domínio da radiação ultravioleta (UV). Em relação às RS, a concentração de peróxidos intracelulares e óxido nítrico aumentou, apesar da ausência de ativação das defesas antioxidantes e da falta de sucesso na reversão da citotoxicidade com inibidores das espécies reativas de oxigênio (ROS). De igual forma, o verapamil não conseguiu prevenir a morte celular. Adicionalmente, os efeitos antiangiogénicos máximos foram obtidos com 60s de exposição ao plasma. Estes resultados sugerem que a CAP poderá ser uma terapia seletiva anti-inflamatória com o potencial de atingir células tumorais e estruturas de suporte.
In developed countries, the number of new diagnosed cancers is expected to keep rising. Considering the increased demand for alternatives to hazardous current treatments, a new therapy based on plasma, the fourth state of matter, has recently raised the medical community’s attention. The aim of this work was to evaluate the effect, selectivity and mechanisms of action of cold atmospheric plasma (CAP) in a human retinoblastoma cell line.An electronic device was designed to generate CAP, in open air, 2mm above multiwell plates where Y79 cell cultures were seeded. Plasma emission spectrum was obtained by a spectrometer. In order to evaluate the cytotoxicity and selectivity of CAP, the metabolic activity of similarly treated Y79 and human fibroblasts HFF1 cells was assessed. Apoptosis detection, analysis of mitochondrial membrane potential (MMP) and cell morphology were performed to clarify the type of cell death. Propidium-iodide/RNAse staining solution for cell cycle study was used and genotoxic effects were evaluated by comet assay. Oxygen and nitrogen reactive species (RS) and oxidative defenses were quantified. In order to explore the effect of electric fields in voltage-gated calcium channels, blockade with verapamil was applied. Clonogenic assay screened for survival. Finally, antiangiogenic effects were tested with aortic ring assay.After 60s of CAP treatment, the metabolic activity of retinoblastoma cells decreased more than 50%, mainly due to apoptosis, while HFF1 remain viable. Cell survival was reduced and an accumulation of cells in S and G2/M phases was observed, however, no DNA strand breaks were detected. Plasma emission spectrum revealed several peaks in ultraviolet (UV) domain. Regarding RS, the concentration of intracellular peroxides and nitric oxide was increased, despite no activation of antioxidative defenses and lack of success in reverting cytotoxicity with reactive oxygen species (ROS) inhibitors. Likewise, verapamil failed to protect cells from cell death. Additionally, maximal antiangiogenic effects were obtained with 60s of plasma exposure.These results suggest that CAP might be an anti-inflammatory selective therapy with the potential to target tumor cells and supporting structures.
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Lopes, Beatriz Pinheiro. "Cold Atmospheric Plasma in the treatment of Retinoblastoma." Master's thesis, 2018. http://hdl.handle.net/10316/86186.
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Dissertação de Mestrado em Bioquímica apresentada à Faculdade de Ciências e TecnologiaCom o aumento do número de novos casos de cancro diagnosticados, novas alternativas aos tratamentos atuais têm sido desenvolvidas. Para o retinoblastoma (RB), o cancro intraocular mais comum em crianças, a procura de novas terapias com efeitos secundários menores tem uma grande relevância. A quimioterapia é das opções terapêuticas atuais com maiores efeitos secundários. Por esta razão, a sua combinação com novas terapias locais tem uma grande importância na investigação clínica. Nos últimos anos surgiu uma nova abordagem terapêutica anticancerígena, o plasma atmosférico frio (CAP). O plasma, quarto estado físico da matéria, é produzido aquando da ionização de átomos e moléculas de um gás. Para avaliar a existência de um possível efeito parácrino, e para ultrapassar alguns dos obstáculos do CAP, foram estudados os meios condicionados (CM) e os meios ativados por plasma (PAM).Esta dissertação permitiu avaliar o efeito do tratamento com PAM sozinho ou em combinação com a carboplatina numa linha celular de retinoblastoma humano. Para avaliar a seletividade das terapias derivadas do CAP, foi avaliada a viabilidade celular e o conteúdo proteico em células de retinoblastoma (Y79), fibroblastos humanos (HFF1) e células humanas do epitélio pigmentado da retina tratadas igualmente. Para clarificar o mecanismo de ação do tratamento com PAM, a sobrevivência celular foi observada pelo ensaio clonogénico. A morfologia celular e a marcação com iodeto de propídeo/RNAse foram realizadas para elucidação sobre o tipo de morte celular e paragem do ciclo celular. As espécies reativas de oxigénio e nitrogénio (RONS), bem como as defesas antioxidantes foram quantificadas. Para o tratamento combinado, foram obtidas curvas dose-resposta da carboplatina (CPT) sozinha e da carboplatina+PAM para avaliar a viabilidade celular e o conteúdo proteico.A viabilidade celular e o conteúdo proteico das células Y79 diminuíram no tratamento direto (CAP), bem como no tratamento indireto (CM e PAM), enquanto que as células HFF1 e RPE-D407 mantiveram-se viáveis em todos os tratamentos. Com o tratamento com PAM, as células Y79 parecem sofrer apoptose, acumulando-se na fase S, e perdendo a capacidade de replicação. A concentração do anião superóxido e óxido nítrico intracelulares está aumentada, enquanto que a concentração intracelular de peróxidos está diminuída. Em relação às defesas antioxidantes, a concentração intracelular da glutationa (GSH) está aumentada, enquanto que a atividade da superóxido dismutase se mantém constante. Com o tratamento da carboplatina, a viabilidade celular e o conteúdo proteico diminuem de uma forma dependente da concentração. A viabilidade celular do tratamento combinado é menor do que a viabilidade da carboplatina e PAM sozinhos. O conteúdo proteico mostra um comportamento semelhante ao da carboplatina sozinha.Estes resultados mostram que as terapias derivadas do CAP têm um efeito anti proliferativo e seletivo em células tumorais. Tendo o tratamento com PAM um efeito semelhante ao tratamento com CAP, mas com uma aplicação clínica mais simples, poderá tornar-se uma nova terapia sólida para retinoblastoma. Estes resultados também sugerem que o tratamento com PAM pode ser uma forte abordagem na terapia adjuvante com a quimioterapia.
With the rising of the number of new diagnosed cases of cancer, alternatives to current treatments have been developed. Being the most common intraocular cancer in children, retinoblastoma (RB) has great relevance in the search for new therapies with less side effects. Chemotherapy is one of the current therapies that have more side effects. For this reason, combination with new local therapies has also importance in clinical research. Cold atmospheric plasma (CAP), a new therapy against cancer, have been developed over the last years. Plasma, fourth physical state of matter, is generated by ionization of gas atoms and molecules. To evaluate the possible existence of a paracrine effect and to overcome some drawbacks of CAP, conditioned medium (CM) and plasma-activated media (PAM) have been studied.This work allowed to evaluate the effect of PAM treatment alone or in combination with carboplatin in human retinoblastoma cell line. To assess the selectivity of CAP derived therapies, the cell viability and protein content were measured in similarly treated retinoblastoma (Y79), human fibroblasts (HFF1) and human retinal pigment epithelial (RPE-D407) cells. In order to clarify the mechanism of action of PAM treatment, surveillance was assessed by clonogenic assay. Cell morphology and propidium-iodide/RNAse staining were performed to elucidate the type of cell death and cell cycle arrest. Reactive oxygen and nitrogen species (RONS), as well as antioxidative defences, were quantified. For combination treatment, dose-response curves to carboplatin (CPT) alone and carboplatin+PAM were performed to assess cell viability and protein content.The cell viability and protein content of Y79 cells decreased in direct treatment (CAP), as well as in indirect treatment (CM and PAM), while HFF1 and RPE-D407 remains viable in all the treatments. With PAM treatment, Y79 cells seems to undergo apoptosis, accumulates in S phase, and lose the replication ability. The concentration of intracellular superoxide anion and nitric oxide was increased, while the intracellular concentration of peroxides was decreased. Regarding antioxidative defences, the intracellular concentration of glutathione (GSH) was increased, while the activity of superoxide dismutase remains stable. With carboplatin treatment, cell viability and protein content were decreased in a concentration dependent manner. The cell viability of combination treatment was lower than the cell viability of carboplatin and PAM alone. The protein content showed a similar behaviour than carboplatin alone.These results show that CAP derived therapies have a selective antiproliferative effect in tumoral cells. Having PAM treatment, a similar effect of CAP treatment, with an easier clinical application, it could become a new therapy for retinoblastoma. These results also suggest that PAM treatment could be a strong approach for adjuvant therapy with chemotherapy.
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Wallenhorst, Lena. "Protective Particle Coatings applied by Cold Plasma Spraying." Doctoral thesis, 2017. http://hdl.handle.net/11858/00-1735-0000-002E-E37A-A.
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Shih, Yi-Cyuan, and 石逸泉. "Application of Atmospheric Cold Plasma-Escalator Sterilization Device." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/c29afx.
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碩士龍華科技大學
化工與材料工程系碩士班
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This report presents a complete document of an atmospheric pressure cold plasma sterilization system for escalator handrail disinfection. The document has been prepared to fulfill its future needs such as patent applications, commercialization, form improvements, plasma performance parameters identification for various applications, future industrial production, etc. The aim of this report is to ensure a successful prototype development of this cold plasma escalator cleaning equipment, and finally the public acceptance of this plasma sterilization technology. A patent map has been made according to the type and scope of patent application, it reveals that in the past five years, there has been 4807 cold plasma sterilization applications worldwide in the area of biomedical engineering. Among these applications, there is a case, US 9034270B2, which is similar to the design of this cold plasma escalator cleaning equipment. A thorough investigation has been made therefore to differentiate these two patent applications, result of the analysis confirms that the subject of this report achieves an effective sterilization rate, up to 90%, after 6 seconds of plasma treatment. In addition, the equipment is compatible to the existing escalator from most of the factories, no changing or modification of the escalator structure is required. The design of this device therefore conforms to the invention patent elements such as "industry availability", "novelty" and "progressive". Experimental prototype of this escalator disinfection device with technology of atmospheri¬c pressure cold plasma has been successfully completed based on the conceptual design, the optimized performance parameters are the frequency of 7kHz~15kHz, the voltage of 3kV~4.5kV pulse voltage, and the total power consumption of 900W ~ 1100W. This report also confirms that the design of this atmospheric pressure cold plasma escalator sterilization device has successfully completed the examination of the invention patent of Taiwan, the reply of the invention patent of the United States and the approval of the new Chinese patent. It is about to be transformed into industrial prototype, and ready to participate in future government-related business competition.
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Jian, Shih-Jie, and 簡士傑. "Research of Atmospheric Pressure Line-shaped Cold Plasma." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/12307139731534034342.
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Galindo, Diego A. "Self-similar solutions of cold-ion plasma equations." 2008. http://www.library.wisc.edu/databases/connect/dissertations.html.
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