Aim of this thesis is to investigate the optimum working parameters of a helium-neon laser. Partial pressure ratios, total pressures of the gases and voltage-current characteristics were studied. The analysis of the results includes the minor factors (impurity, volume, etc.) and their effects to main parameters (laser power, voltage, current). Tables, which were formed by measured optical parameters as wavelength and power, converted to graphs and from these graphs optimal working conditions for the laser are obtained.

Laser diagnostics are fast-response, non-intrusive and species-specific tools perfectly applicable for studying combustion processes. Quantitative measurements of species concentration and temperature require spectroscopic data to be well-known at combustion-relevant conditions. Absorption cross-section is an important spectroscopic quantity and has direct relation to the species concentration. In this work, the absorption cross-sections of basic hydrocarbons are measured using Fourier Transform Infrared (FTIR) spectrometer, tunable Difference Frequency Generation laser and fixed wavelength helium-neon laser. The studied species are methane, methanol, acetylene, ethylene, ethane, ethanol, propylene, propane, 1-butene, n-butane, n-pentane, n-hexane, and n-heptane. The Fourier Transform Infrared (FTIR) spectrometer is used for the measurements of the absorption cross-sections and the integrated band intensities of the 13 hydrocarbons. The spectral region of the spectra is 2800 – 3400 cm-1 (2.9 – 3.6 μm) and the temperature range is 673 – 1100 K. These valuable data provide huge opportunities to select interference-free wavelengths for measuring time-histories of a specific species in a shock tube or other combustion systems. Such measurements can allow developing/improving chemical kinetics mechanisms by experimentally determining reaction rates. The Difference Frequency Generation (DFG) laser is a narrow line-width, tunable laser in the 3.35 – 3.53 μm wavelength region which contains strong absorption features for most hydrocarbons due to the fundamental C-H vibrating stretch. The absorption cross-sections of propylene are measured at seven different wavelengths using the DFG laser. The temperature range is 296 – 460 K which is reached using a Reflex Cell. The DFG laser is very attractive for kinetic studies in the shock tube because of its fast time response and the potential possibility of making species-specific measurements. The Fixed wavelength helium-neon (HeNe) laser at 3.39 μm is used to measure the absorption cross-section of the fuels mentioned above. The dependence on temperature, pressure and bath gas (helium, argon and nitrogen) is also examined. The temperature and pressure ranges of this study are 296 – 800 K and 250 – 1000 Torr, respectively. These are the first measured cross-sections at HeNe laser wavelength that are applicable at combustion-relevant conditions.

Orientador: Liana Maria Cardoso Verinaud / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Biologia / Made available in DSpace on 2018-08-21T05:41:31Z (GMT). No. of bitstreams: 1 AlvesdaCosta_Thiago_M.pdf: 4142749 bytes, checksum: 3a67ca785afa76fb4962f6825b00c86b (MD5) Previous issue date: 2012 / Resumo: Nosso grupo tem explorado os mecanismos biológicos que fundamentam o processo inflamatório das lesões paracoccidioidomicóticas cutâneas, causadas pela inoculação de leveduras no coxim plantar esquerdo de camundongos BALB/c, quando tratadas com laser HeNe. Neste trabalho, é mostrado que camundongos tratados com laser apresentaram redução do edema da pata, maior organização histológica, menor infiltrado inflamatório, maior organização do tecido de granulação ao redor da lesão, e imunomarcação maior da iNOS. A imunomarcação da elastase não apresentou diferenças estatisticamente significativas. Além disso, a atividade da SOD e a produção de NO foram aumentadas. A expressão gênica das quimiocinas inflamatórias CCL3 e CXCL10 é menor nos animais tratados com 3 sessões de irradiação, enquanto que a expressão de CCL5 não apresentou diferenças significativas. A citometria de fluxo revelou uma maior porcentagem de macrófagos, em detrimento de menores números de neutrófilos, ao longo do tratamento. A porcentagem de células NK e NKT ligeiramente mais elevada após a sessão primeiro laser. No linfonodo poplíteo esquerdo, após uma sessão de tratamento com o laser, a porcentagem de macrófagos e neutrófilos é maior nos animais tratados, após 3 sessões de tratamento a porcentagem dessas células é igual nos 2 grupos experimentais, no entanto, a porcentagem de células dendríticas maduras é maior nos animais tratados. A quantidade de linfócitos T CD4+ é maior no linfonodo dos animais tratados com 2 sessões de irradiação, enquanto que a quantidade de T CD8+ é menor. No seu conjunto estes resultados apontam para um duplo efeito do tratamento, diminuindo a resposta inflamatória e acelerando a cicatrização das lesões. Neste sentido, o laser de HeNe pode ser considerado como uma nova estratégia de terapia a ser utilizada como uma ferramenta adjuvante aos agentes anti-fúngicos para melhorar o tratamento de lesões de paracoccidioidomicóticas (PCM) / Abstract: Our group has been exploring the biological mechanisms underlying the inflammatory process of paracoccidioidomycotic lesions treated by HeNe laser on cutaneous lesions caused by the inoculation of yeast cells into the back foot-pad of Balb/c mice. In this work we showed that laser-treated mice presented reduction of footpad edema, greater histologic organization, milder inflammatory infiltrate, higher organization of the granulation tissue around the lesion, and enhanced immunolabeling of iNOS. The immunolabeling of elastase showed no significant alterations. In addition the SOD activity and NO production were increased. Chemokines CCL3 and CXCL10 showed decreased levels in animals treated with 3 laser sessions, but no significant difference was observed in realtion to CCL5 expression. Also, a higher percentage of macrophages, in detriment of lower neutrophil numbers, were observed throughout the treatment. The percentage of NK and NKT cells were slightly higher after the first laser session. At the popliteal lymph node after one laser session the percentage of macrophages and neutrophils population were increased, after three laser sessions those percentages were similar with the non-treated group, however the mature dendritic cell population percentage was higher on the treated animals. CD4+ T Lymphocytes percentage was higher in animals treated with two laser sessions while CD8+ percentage was lower. Altogether these results point towards a dual effect of the treatment, decreasing the inflammatory response and accelerating the healing of the lesions. We believe that HeNe laser is a new non-harmful strategy that may be used as an adjuvant tool to be combined with anti-fungal agents for improving the treatment of PCM lesions / Mestrado / Imunologia / Mestre em Genética e Biologia Molecular