A nonthermal carbon monoxide plasma is known to produce a solid deposition which is thought to be a polymer of carbon suboxide (C3O2); however there are very few investigations of this deposition in the literature. This thesis contains an analysis of the theoretical thermodynamics and kinetics of carbon suboxide formation as well as experimental results. The theoretical analysis suggests that carbon suboxide may be an equilibrium product even at ambient conditions but favors lower temperatures; furthermore if solid carbon is considered to be kinetically limited, and therefore not a product, then carbon suboxide is more likely to be a product under these pseudo-equilibrium conditions. Experimentally, solid films were produced in a dielectric barrier discharge (DBD) containing pure carbon monoxide. Optical emission spectroscopy was used to analyze the plasma and models of the emission spectra were created to determine the plasma temperatures. Deposition rates were determined to be on the order of 0.2 mg/min at a power of about 10W; it is expected however that these conditions are not optimized. The overall kinetics of carbon suboxide was analyzed and optimal conditions for operation can be estimated. Characterization of the solid depositions were carried out using Solid State Nuclear Magnetic Resonance (NMR), Fourier Transform Infrared Spectroscopy (FTIR), Electrospray Ionization Mass Spectroscopy (ESI-MS), and Matrix-assisted Laser Desorption Ionization Mass Spectroscopy (MALDI-MS). The characteristics of the film are very comparable to hydrolyzed carbon suboxide polymer suggesting that carbon suboxide polymer were in fact created in the carbon monoxide plasma at atmospheric conditions.

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Milk is one of the eight major food allergens. Cow's milk allergy is the most common allergy in children under 2 years of age. About 1.6 to 2.8 percent of children under this age are reported to have cow's milk allergy. Casein, β-lactoglobulin and α-lactalbumin are major milk protein allergens. Nonthermal treatments like high intensity ultrasound, ultraviolet (UV) light and nonthermal plasma treatments have been reported in the literature to be effective in reducing the allergenicity of different food proteins. Hence it was expected for these treatments to reduce cow milk allergenicity. The objective of this study was to investigate the effect of high intensity ultrasound, nonthermal atmospheric plasma and UV-C light treatments in reducing the allergenicity of isolated major milk proteins. Sonics Vibracell VC 505 ultrasonic liquid processor was used to perform high intensity ultrasound treatments. UV light treatments were performed using a DDK Scientific Corporation UV tunnel. A nonthermal atmospheric plasma setup assembled in Department of Microbiology lab was used to perform plasma treatments. Samples were analyzed using sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) to estimate the change in protein concentration and enzyme linked immuno sorbent assays (ELISA) to observe the change in IgE binding. A one-way analysis of variance was conducted to evaluate the relationship between treatment time and percent IgE binding at 95% confidence level. Further investigation was conducted with nuclear magnetic resonance (NMR) spectroscopy on treated casein to assess any change in the structure of protein. SDS-PAGE results for ultrasound and plasma treatments didn't show any change in gel band intensities for casein, β-lactoglobulin and α-lactalbumin indicating no significant change in protein concentration. Ci-ELISA analysis showed that there was no significant difference (p>0.05) in IgE binding values for control and treated samples in ultrasound and plasma treatment conditions tested in this study. The intensities of all the three protein bands in SDS-PAGE gel were reduced by UV-C light treatment at 15 min treatment time. In Ci-ELISA, there was a significant difference (p< 0.05) in IgE binding values for control and treated samples and a reduction in allergenicity of proteins (25% reduction for casein and 28% reduction for whey protein fractions) was observed. Further investigations using in vivo clinical trials need to be conducted to confirm this result. NMR results didn't show any noticeable changes in the structures of casein with all three different treatments. In conclusion, UV-C light treatment can reduce the allergenicity of isolated major milk proteins to some extent. High intensity ultrasound and nonthermal atmospheric plasma treatments failed to generate effective results for reducing allergenicity at the conditions tested in this study. Higher intensity and longer treatment conditions might yield better results with ultrasound treatment. Different power and gas flow rates used to generate plasma with direct exposure of proteins might yield better results towards reducing the allergenicity of major milk allergens.

Orientador: Munemasa Machida / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Física Gleb Wataghin / Made available in DSpace on 2018-08-24T01:40:20Z (GMT). No. of bitstreams: 1 Aguera_JoaoJulioMendes_M.pdf: 1866218 bytes, checksum: 21fe14d8d370e0121be6f854084afb06 (MD5) Previous issue date: 2013 / Resumo: Os plasmas DBD, Descargas com Barreira de Dielétrico, em pressões atmosféricas têm despertado grande interesse nas pesquisas nos últimos anos, principalmente pelas suas aplicações práticas: deposição de materiais, tratamento de superfícies, tratamento de cáries, esterilização de bactérias e destruição de células cancerígenas. Estes plasmas são chamados de plasmas não-térmicos e diferem dos plasmas de alta temperatura (estelares e de reatores de fusão nuclear) e dos plasmas térmicos (tochas de plasmas e plasmas industriais), por possuírem temperaturas translacional, eletrônica, vibracional e rotacional distintas. Para determinar a temperatura de plasmas DBD em descargas elétricas nos gases Ar e He, utilizamos um método indireto que avalia a temperatura por meio de um plasma de Nitrogênio molecular formado pela colisão dos plasmas de Ar e He com o Nitrogênio presente no ar. O espectro luminoso deste plasma é medido, as principais linhas de emissão catalogadas e depois analisado com um software específico para determinação de temperaturas de gases moleculares. Também são mostradas aqui algumas das principais técnicas de espectroscopia usadas na captação de espectros luminosos de plasmas laboratoriais, realizadas em dois dispositivos, plasma DBD produzido com jato de seringa, e plasma fracamente ionizado produzido com uma descarga DC entre dois eletrodos / Abstract: Research on DBD (Dieletrical Barrier Discharges) plasmas at atmospheric pressure have attracted attention and great interest on its research upon the last few years, mostly because of its practical applications: material deposition, surface treatment, cavity treatment, bacterial sterilization and cancer cell destruction. These plasmas are called nonthermal plasmas and differ from the high temperature plasmas (stellar and fusion reactors) and thermal plasmas (plasma torches and industrial plasmas) because of its distinct translational, electronic, vibrational and rotational temperatures. For temperature determination in DBD plasmas formed by electrical discharges on Ar and He gases, an indirect method is used evaluating the temperature of molecular nitrogen plasma formed by collision between the Ar and He plasmas with the nitrogen present in air. The luminous specter of this plasma is measured, the principal emission lines cataloged and then analyzed with specific software for molecular gases temperature determination. The main spectroscopic techniques used for analysis of the luminous spectra obtained from two devices: DBD plasma generated by a syringe jet and weakly ionized plasma produced by a DC discharge between two electrodes, are show on this thesis / Mestrado / Física / Mestre em Física

Background: Bacterial contamination of surfaces with methicillin-resistant Staphylococcus aureus (MRSA) is a serious problem in the hospital environment and is responsible for significant nosocomial infections. The pathogenic contaminants form biofilms, which are difficult to treat with routine biocides. Thus, a continuous search for novel disinfection methods is essential for effective infection control measures. This demonstration of a novel technique for the control of virulent pathogens in planktonic form as well as in established biofilms may provide a progressive alternative to standard methodology. Methods: We evaluated a novel technique of normal atmospheric nonthermal plasma known as floating-electrode dielectric-barrier discharge (FE-DBD) plasma against a control of planktonic and biofilm forms of Escherichia coli, S aureus, multidrug-resistant methicillin-resistant S aureus (MRSA) -95 (clinical isolate), -USA300, and -USA400, using widely accepted techniques such as colony count assay, LIVE/DEAD BacLight Bacterial Viability assay, and XTT (2,3-Bis(2-methoxy-4-nitro-5-sulfophenyl)-2H-tetrazolium-5-carboxanilide) assay. Results: Exposure of free living planktonic forms of E coli, S aureus, and MRSA were rapidly inactivated by DBD plasma. Approximately 107 bacterial cells were completely (100%) killed, whereas 108 and 109 were reduced by approximately 90% to 95% and 40% to 45%, respectively, in less than 60 seconds (7.8 J/cm2) and completely disinfected in ≤120 seconds. In established biofilms, the susceptibility of MRSA USA400 was comparable with USA300 but less susceptible than MRSA95 (clinical isolate), S aureus, and E coli (P < .05) to FE-DBD plasma, and plasma was able to kill MRSA more than 60% within 15 seconds (1.95 J/cm2). The killing responses were plasma exposure-time dependent, and cell density dependent. The plasma was able disinfect surfaces in a less than 120 seconds. Conclusion: Application of DBD plasma can be a valuable decontamination technique for the removal of planktonic and biofilm-embedded bacteria such as MRSA -USA 300, -USA 400, methicillin-sensitive S aureus (MSSA), and E coli, the more common hospital contaminants. Of interest, E coli was more resistant than S aureus phenotypes.

The aim of this thesis was to elaborate the issue of the decomposition of volatile organic compounds in the Gliding Arc plasma discharge at atmospheric pressure. Technologies based on nonthermal plasma could offer a good alternative to conventional techniques for the decomposition of volatile organic compounds, such as thermal and catalytic oxidation. Gliding Arc discharge (GidArc) is a widely exploited nonthermal plasma source used for many industrial applications, such as air-pollution control. The energy efficiency, reaction selectivity or production of specific species may be achieved in this kind of plasma, and thus for various chemical processes it can be much more effective then in conventional techniques. Presented experiments are linked to the previous results published in diploma thesis, which gave us the basics for construction of new reactor and optical emission spectroscopy measurements have been done to characterize the plasma. Toluene (aromatic, unsaturated), cyclohexane (aromatic, saturated) and hexane (aliphatic, saturated) were used as the model compounds for these experiments in the concentration range from hundreds to thousands ppm. Results focused on the electrical parameters of the reactor were carried out, with the aim to operate the system at a lower energy cost. In order to get the time-resolved diagnostics of the moving plasma channel, the evolution of the plasma channel was recorded continuously by using a high-speed video camera. In next part of the work, some results concerning generation of low molecular products like nitric oxide, nitrogen dioxide, hydrogen and carbon monoxide on the discharge conditions are presented. In combustion process, undesirable mixture of toxic highmolecular by-products can be formed. Samples were therefore analysed in gas chromatograph linked to mass spectrometer, to characterize the chemical transformation pathway of VOC in plasma.

Orientadores: Jayr de Amorim Filho, Marco Aurélio Pinheiro de Lima / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Física Gleb Wataghin / Made available in DSpace on 2018-08-24T21:57:52Z (GMT). No. of bitstreams: 1 Ridenti_MarcoAntonio_D.pdf: 6265448 bytes, checksum: 384897ffe1b8b10a23a0ab7c3b206b76 (MD5) Previous issue date: 2014 / Resumo: Neste trabalho plasmas não térmicos gerados em pressão atmosférica e sustentados por ondas de superfície em micro-ondas, tendo o argônio como gás de alimentação, foram estudados experimentalmente e teoricamente tendo em vista aspectos pouco compreendidos de suas propriedades físicas e aplicações voltadas ao tratamento de biomassa. Medições da composição elementar e dos parâmetros físicos foram realizados por meio de técnicas de diagnóstico baseadas em espectrometria de massa e espectroscopia óptica de emissão. O sistema físico foi modelado por meio das equações de continuidade das espécies neutras e carregadas, da equação do calor e da equação de Boltzmann dos elétrons, que foram acopladas utilizando um procedimento auto-consistente. Uma vez obtido o quadro geral das propriedades do plasma, foi estabelecida a condição de operação adequada ao tratamento das amostras derivadas de biomassa. O tratamento foi realizado sobre quatro tipo de amostras: lignina, xilana, celulose e bagaço de cana-de-açúcar. Dentre as contribuições importantes deste trabalho podem ser destacadas: (i) a verificação experimental do papel dos íons moleculares do argônio no processo de contração da descarga; (ii) a determinação do perfil axial no plasma dos principais íon positivos e negativos, da densidade e temperatura eletrônicas, da temperatura do gás e da densidade do estado metaestável Ar(1s5); (iii) verificação da seletividade do tratamento a plasma, tendo sido observada uma alteração significativa dos espectros de absorção no infravermelho nos casos da lignina e da xilana, mas não no caso da celulose. Esse último resultado sugere uma rota inusitada para novas tecnologias de deslignificação e síntese de novos materiais a partir de biomassa / Abstract: In this work non-thermal argon plasmas produced at atmospheric pressure and sustained by microwave surface waves were theoretically and experimentally studied in view of their non understood aspects and also the applications aimed at biomass treatment. Measurements of elemental composition and physical parameters were carried by means of plasma diagnostic techniques such as mass spectrometry and optical emission spectroscopy. Plasma modelling based on the self-consistent solution of the continuity equations of the neutral and charged species, the heat equation and the electron Boltzmann equation was developed to describe the plasma properties. Once a complete picture of the plasma behaviour was obtained, a promising condition for plasma treatment was established. Four types of biomass derived material were plasma treated: lignin, cellulose, xylan and sugarcane bagasse. Among the important contributions of this work one may highlight the following: (i) the experimental verification of the crucial role of argon molecular ions in the discharge contraction; (ii) axial profile determination of the main positive and negative ions, the electronic temperature and density, the gas temperature and the metastable state Ar(1s5) density; (iii) important modification of the infrared absorption spectra after plasma treatment in the cases of lignin and xylan, but not in the case of cellulose, suggesting a unexpected route for delignification and new materials synthesis from biomass / Doutorado / Física / Doutor em Ciências

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