The repair of automobiles is a critical aspect in vehicle ownership and is potential source of volatile toxic compounds being brought into a home when repairs are conducted in an attached garage. The goal of this study was to assess the impact of the repair of automobiles in an attached garage on the exposure of the home mechanic and degradation of indoor air. Five common automotive tasks were performed in two garages with the garage door either opened 30.5 centimeters (n=5) or closed (n=4). The exposure to the home mechanic, the behavior of contaminants within the garage, and infiltration of contaminants in the home were the determinants of interest. Integrative sampling incorporating charcoal sorbent sampling tubes analyzed by gas chromatography and directs reading photo ionization detectors were used to assess exposure. The tasks with the greatest contributions to the home mechanic’s exposure were found to be brake pad replacement and oil change; these generated 95th percentile concentrations of 51.2 ppm and 12.8 ppm, respectively, with the garage door closed. In contrast, the tasks of refueling and shock replacement had 95th percentile contributions of 0.85 ppm and 2.99 ppm, respectively, in the closed garage. Equations were fitted to the aggregated concentrations during decay to estimate general ventilation (Q/V) in a closed garage. The contaminants within the garage were not found to infiltrate into the home as the average concentrations within the home never exceeded 1 ppm. It was found that automotive repair work in a closed garage may constitute up to 18% of threshold limit value of toluene over a 105 minute exposure at home. Automotive repair inside an attached garage has the potential to make a significant contribution to a mechanic’s daily exposure and should be incorporated into occupational exposure assessments of volatile organic compounds.

No description available.

No description available.

<p> Matrix diffusion from planar fractures was studied both mathematically and through physical model experiments. A conceptual model was developed based on previous work by Parker (1994) and Crank (1956). Mathematical models were developed to simulate diffusion from 2D and 3D instantaneous disk sources and a 3 D continuous disk source. The models were based on analytical solutions previously developed by Carslaw and Jaeger (1959). Analytical solution is not available for the total mass diffused into the porous matrix for a 3D continuous disk source, and it was therefore calculated through the summation of the iso-concentration lines, which were assumed to be a semi-spherical shape.</p> <p> The mathematical simulations indicated that the 2D scenario produces significantly different results from the 3D scenario, the time for mass disappearance is significantly larger for continuous sources than for instantaneous sources, the normalized concentration generally decreased over time for instantaneous sources while it increased over time for continuous sources, diffusion rates decrease significantly over time and space, and the normalized mass loss from the source zone never reaches 1 for continuous sources due to the semi-infinite integral. The simulations also showed that disappearance times increase exponentially with increasing source radii and matrix porosity, and decrease with increasing aqueous-phase NAPL solubilities.</p> <p> The observations from the physical model experiments were very close to the simulated data at z = 0, validating the 3D mathematical models for this elevation. A plot of the observed vs simulated data did not reveal any trends, indicating that the majority of the differences can be attributed to experimental error. The experimental concentrations were below the method detection limit at depths of 3 and 6 cm however, indicating that either the experiments should have been conducted over a longer time period or a more sensitive analytical method should have been employed, to enable model validation at these depths.</p> / Thesis / Master of Applied Science (MASc)

No description available.

O grafeno é um material bidimensional (2D) com espessura monoatômica, formado por átomos de carbono com hibridização sp2. Ele é a base das estruturas grafíticas, como os fulerenos, os nanotubos de carbono e o grafite, possuindo excepcionais propriedades eletrônicas, térmicas, mecânicas e ópticas. Entre os métodos de obtenção do grafeno, a esfoliação química do grafite em fase líquida é altamente promissora, pois pode ser escalonada, possibilitando a produção de grandes volumes. Além disso, apresenta alta versatilidade em termos de funcionalização química do grafeno e produção de filmes finos para a confecção de compósitos e de eletrodos transparentes e condutores. Desde que as singulares propriedades mecânicas e condutoras das nanoestruturas de carbono estão associadas a espécies individuais isoladas, a dispersão e estabilização de grafenos em diferentes líquidos são de extrema importância em estudos fundamentais e aplicados. Para tal, o potencial atrativo entre as folhas no grafite deve ser balanceado por um potencial repulsivo. Assim, o custo energético das interações grafeno-solvente, que depende fortemente do material de partida e das propriedades dielétricas do meio, precisa ser entendido. Teorias de solubilidade têm sido recentemente aplicadas a nanoestruturas de carbono. Neste estudo, usamos os parâmetros de solubilidade de Hansen para a proposição de solventes e misturas capazes de esfoliar em fase líquida o grafite natural da empresa Nacional de Grafite Ltda.. Utilizando um algoritmo no Matlab baseado nos parâmetros de solubilidade de Hansen, selecionou-se cinco misturas de solventes orgânicos, onde o clorofórmio é um dos componentes. O grafite natural na forma bruta e pré-esfoliada foi esfoliado em dispersões estáveis de grafenos, as quais foram caracterizadas por espectroscopia no UV-Vis e Raman, MET e DLS. As dispersões produzidas nas misturas de menor valor de D0, apesar de apresentarem uma menor concentração de material disperso, apresentaram flakes de tamanho maior e com poucas camadas de grafeno. Já nas misturas com maior valor de D0, observou-se uma maior concentração de material disperso, com grafenos de dimensões maiores e menores, porém com maior número de camadas. / Graphene is a two-dimensional material (2D) composed by a monoatomic thickness sheet of carbon atoms with sp2 hybridization. It is the basis of graphitic structures, such as fullerenes, carbon nanotubes and graphite, possessing exceptional electronic, thermal, mechanical and optical properties. The method of graphene obtention through graphite exfoliation in liquid phase is highly promising because it can be staggered, allowing the production of large quantities. In addition, it presents high versatility in terms of chemical functionalization of graphene and thin films production for the manufacture of composites and transparent and conducting electrodes, respectively. Since natural and mechanical properties of conductive carbon nanostructures are associated with individual isolated species, dispersion and stabilization of graphene in different liquids are of utmost importance in basic and applied studies. For this purpose, the attractive potential between the graphene sheets in the graphite must be balanced by a repulsive potential. Thus, the energy cost of graphene-solvent interactions, which strongly depends on the starting material and the dielectric properties of the medium, needs to be understood. Solubility theories have recently been applied to carbon nanostructures. In this study, we have used the Hansen solubility parameters for proposing solvent mixtures able to exfoliate the natural graphite from the Nacional de Grafite Ltda. company in the liquid phase. Using an algorithm in Matlab based on the Hansen solubility parameters, we have selected five mixtures of organic solvents, where chloroform is one of the components. The natural graphite in raw form and pre-exfoliated was exfoliated in stable dispersions of few-layer graphenes, which were characterized by UV-Vis and Raman spectroscopy, transmission electron microscopy (TEM) and dynamic light scattering (DLS). Dispersions produced in mixtures of lower value of D0, despite having a lower concentration of dispersed material, showed larger flakes size with few-layers of graphene. Mixtures with a higher value of D0 presented a higher concentration of dispersed material, but particles with smaller dimensions and a greater number of layers.

Neste estudo foi investigada a alcoólise enzimática do óleo de soja com etanol, utilizando t-butanol como solvente e enzimas imobilizadas Lipozyme TL IM, Lipozyme RM IM e Novozym 435 como catalisadores. As reações foram realizadas em um reator batelada fechado acoplado a um condensador e com constante agitação. Foram avaliadas a influência do t-butanol, do tipo de enzima utilizada, da razão molar álcool/óleo e da temperatura no rendimento em biodiesel. A etanólise do óleo de soja por sucessivas adições de álcool foi investigada e as melhores condições foram obtidas em presença de t-butanol, razão molar etanol/óleo igual a 3, temperatura de 50C e 5% (m/m) de Novozym 435. Nas reações conduzidas em presença de t-butanol não foram observadas diferenças significativas entre a adição direta e a escalonada do álcool. Os efeitos da adição de álcool só foram observados na ausência de t-butanol. O rendimento máximo em ésteres etílicos atingido foi cerca de 66% após 4h de reação com Novozym 435 na presença de solvente. / In this research, the enzymatic alcoholysis of soybean oil was investigated by using commercial immobilized lipases: Lipozyme TL IM, Lipozyme RM IM and Novozym 435 as catalysts. The reactions were carried out in a closed batch reactor with constant stirring and coupled with condenser. The influence of t-butanol, type of enzyme, molar ratio (alcohol/soybean oil) and temperature on biodiesel yield were evaluated. The ethanolysis of soybean oil by stepwise additions of ethanol was also investigated. The best conditions were obtained in t-butanol presence with ethanol/oil molar ratio of 3, temperature of 50oC and 5 wt.% Novozym 435. For the reactions carried out with t-butanol, the effects of stepwise alcohol addition were not observed, but it was realized in t-butanol absence. The maximum biodiesel yield achieved was 66% after 4h of reaction with Novozym 435 in t-butanol system.

Submitted by Cássia Santos (cassia.bcufg@gmail.com) on 2016-08-10T10:25:28Z No. of bitstreams: 2 Dissertação - Roger Cardoso Moreira - 2015.pdf: 8605588 bytes, checksum: 30a0478ee44e03b86b3d5b0eec4354c1 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Approved for entry into archive by Luciana Ferreira (lucgeral@gmail.com) on 2016-08-10T12:09:17Z (GMT) No. of bitstreams: 2 Dissertação - Roger Cardoso Moreira - 2015.pdf: 8605588 bytes, checksum: 30a0478ee44e03b86b3d5b0eec4354c1 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Made available in DSpace on 2016-08-10T12:09:17Z (GMT). No. of bitstreams: 2 Dissertação - Roger Cardoso Moreira - 2015.pdf: 8605588 bytes, checksum: 30a0478ee44e03b86b3d5b0eec4354c1 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Previous issue date: 2015-12-01 / This study describes the development of an analytical methodology for the separation of quaternary amines using nonaqueous electrophoresis microchips coupled with capacitively coupled contactless conductivity detection (C4D). Initially, preliminary experiments were performed to evaluate two electrokinetic modes for sample introduction on chip, known as gated and floating approaches. Gated injection showed repeatability slightly better than floating mode. In addition, it also provided better analytical responses on the C4D system. During the development of analytical methodology for NAME-C4D, the electrolyte composition was optimized to ensure satisfactory separations on electrophoresis microchips. The electrolyte composed of sodium deoxycholate (NaDCHA) at concentration of 10 mmol/L dissolved in a mixture of MeOH/ACN at the ratio 90:10 (v/v) exhibited separations with high efficiency and resolution above 1. Then, it was realized the optimization of potential injection, separation and detection parameters (frequency and amplitude). Running electrolyte was prepared in both DMSO and DMF, however, the use of a mixture containing MeOH/ACN provided best analytical performance. The best results were obtained with electrolyte containing 10% ACN and 90% MeOH. In addition, different electrolyte compositions were also evaluated, but the electrolyte containing NaDCHA offered results slightly better when compared to others. The optimization of running buffer allowed the separation of nine quaternary amines in electrophoresis channels with effective length of 7.0 cm with analysis time lower than 120 s. The peak resolution was higher than 1 and the calculated separation efficiencies ranged from 77.000 to 185.000 pratos/m. This excellent performance was achieved using NAME conditions under high electric fields. The developed methodology was used for the analysis of quaternary amines in samples containing high salinity levels through the standard addition method. Linear correlation coefficients were obtained up to 0,990 for eight quaternary amines. Lastly, the use of NAME-C4D allowed to observe a strong dependence of the detector response according to the carbon number of quaternary amine molecules. / O presente trabalho descreve o desenvolvimento de uma metodologia analítica para separação de aminas quaternárias utilizando eletroforese não aquosa em microchips (NAME, do inglês non-aqueous microchip electrophoresis) com detecção condutométrica sem contato acoplada capacitivamente (C4D, do inglês capacitively coupled contactless conductivity detection). Inicialmente foi realizado um estudo para avaliação de dois modos de introdução da amostra nos microchips, denominados de gated e floating. O modo gated apresentou repetitividade ligeiramente melhor que o modo floating, além de proporcionar melhores respostas do detector C4D. No desenvolvimento da metodologia utilizando NAME-C4D, foi realizado um estudo para encontrar a composição ideal do eletrólito para as separações eletroforéticas. O eletrólito constituído de deoxicolato de sódio (NaDCHA), na concentração de 10 mmol/L, dissolvido em uma mistura de MeOH/ACN na proporção 90:10 (v/v), apresentou separações com alta eficiência e resolução superior a 1. A partir de então, foi realizada a otimização dos potenciais de injeção, separação e dos parâmetros de detecção (frequência e amplitude). Durante o desenvolvimento da metodologia, foram avaliados eletrólitos preparados em outros dois solventes, DMSO e DMF. Porém, a mistura de MeOH/ACN como solvente forneceu os melhores resultados, desta maneira também foi avaliada a adição de diferentes proporções de MeOH/ACN. Os melhores resultados foram obtidos com o eletrólito contendo 10% de ACN e 90% de MeOH. Na sequência, foram avaliadas diferentes composições do eletrólito, com a adição de outros compostos em substituição ao NaDCHA. Todos os eletrólitos avaliados apresentaram ótimas separações, porém o eletrólito com NaDCHA apresentou resultados ligeiramente superiores. Com a otimização da metodologia desenvolvida, obteve-se separações eletroforéticas de nove aminas quaternárias em microssistema contendo comprimento efetivo de 7,0 cm, com um tempo de análise inferior a 120 s. As separações apresentaram resolução superior a 1 e valores de eficiência entre 77,000 e 185,000 pratos/m, uma vez que com a utilização de solventes orgânicos, foi possível a aplicação de campos elétricos elevados. A metodologia desenvolvida foi avaliada através da determinação das aminas quaternárias, pelo método de adição de padrão, em uma matriz com elevada salinidade. Foram obtidos coeficientes de correlação lineares acima de 0,990 para oito aminas quaternárias. Durante o desenvolvimento do trabalho, foi observada uma clara dependência das respostas analítica em função da quantidade de carbono da molécula.

<p>The thesis describes an investigation into the interaction between the conducting polymer and cellulosic materials, and the preparation of electroconductive paper. The adsorption behavior of the conducting polymer onto cellulosic materials was characterized. Poly(3,4-ethylenedioxythiophene) doped with poly(4-styrene sulfonate) (PEDOT:PSS) was used as conducting polymer because of its attractive properties in terms of conductivity, water solubility, and environmental stability. The model substrate used for adsorption was microcrystalline cellulose (MCC). Various pH levels and salt concentrations were explored to completely understand the adsorption behavior of PEDOT:PSS. The variation in surface charge characteristics when the pH and salt concentration were changed was monitored by polyelectrolyte titration and zeta potential measurement. The adsorption isotherm showed a broad molecular distribution of the conducting polymer and considerable interaction between the polymer and MCC. As the pH of the solution was increased, the adsorbed amount decreased. With varying salt concentrations, the adsorption passed through a maximum. The extent of deposition of PEDOT:PSS on the surface of cellulosic fibers was investigated using X-ray Photoelectron Spectroscopy (XPS) with a commercial base paper as substrate. XPS analysis of dip-coated paper samples showed PEDOT enrichment on the surface. The degree of washing the dip-coated paper with acidic water did not significantly affect the PEDOT enrichment on the surface.</p><p> </p><p>A base paper was coated with PEDOT:PSS blends to produce electroconductive papers. The bulk conductivities (σ_dc) of the coated papers were measured using a four-probe technique and impedance spectroscopy. One-side and two-side coating gave comparable conductivity levels. Various organic solvents added to the PEDOT:PSS dispersion at different concentrations showed various effects on the bulk conductivity of the coated paper. Blends containing sorbitol and isopropanol did not enhance the bulk conductivity of the coated paper, and at high concentrations these organic solvents lowered the conductivity. Paper samples coated with a PEDOT:PSS blend containing N-methylpyrrolidinone (NMP) and dimethyl sulfoxide (DMSO) exhibited a higher conductivity than when coated with pure PEDOT:PSS, due to conformational changes and their plasticizing effect. The effect of calendering was investigated and only the sample subjected to 174 kN/m line load after coating showed significant conductivity enhancement. The addition of TiO₂ pigment lowered the bulk conductivity of the paper. Contact angle measurements were made to monitor the effect of coating the paper with PEDOT:PSS blends on the hydrophilicity of the paper samples. The amount of PEDOT:PSS deposited in the fiber network was determined using total sulfur analysis. Thus, this study makes use of conventional paper surface treatment as method for achieving bulk conductivity of paper in the semi-conductor range without significantly decreasing the paper strength.</p> / Printed Polymer Electronics

The thesis describes an investigation into the interaction between the conducting polymer and cellulosic materials, and the preparation of electroconductive paper. The adsorption behavior of the conducting polymer onto cellulosic materials was characterized. Poly(3,4-ethylenedioxythiophene) doped with poly(4-styrene sulfonate) (PEDOT:PSS) was used as conducting polymer because of its attractive properties in terms of conductivity, water solubility, and environmental stability. The model substrate used for adsorption was microcrystalline cellulose (MCC). Various pH levels and salt concentrations were explored to completely understand the adsorption behavior of PEDOT:PSS. The variation in surface charge characteristics when the pH and salt concentration were changed was monitored by polyelectrolyte titration and zeta potential measurement. The adsorption isotherm showed a broad molecular distribution of the conducting polymer and considerable interaction between the polymer and MCC. As the pH of the solution was increased, the adsorbed amount decreased. With varying salt concentrations, the adsorption passed through a maximum. The extent of deposition of PEDOT:PSS on the surface of cellulosic fibers was investigated using X-ray Photoelectron Spectroscopy (XPS) with a commercial base paper as substrate. XPS analysis of dip-coated paper samples showed PEDOT enrichment on the surface. The degree of washing the dip-coated paper with acidic water did not significantly affect the PEDOT enrichment on the surface.   A base paper was coated with PEDOT:PSS blends to produce electroconductive papers. The bulk conductivities (σdc) of the coated papers were measured using a four-probe technique and impedance spectroscopy. One-side and two-side coating gave comparable conductivity levels. Various organic solvents added to the PEDOT:PSS dispersion at different concentrations showed various effects on the bulk conductivity of the coated paper. Blends containing sorbitol and isopropanol did not enhance the bulk conductivity of the coated paper, and at high concentrations these organic solvents lowered the conductivity. Paper samples coated with a PEDOT:PSS blend containing N-methylpyrrolidinone (NMP) and dimethyl sulfoxide (DMSO) exhibited a higher conductivity than when coated with pure PEDOT:PSS, due to conformational changes and their plasticizing effect. The effect of calendering was investigated and only the sample subjected to 174 kN/m line load after coating showed significant conductivity enhancement. The addition of TiO2 pigment lowered the bulk conductivity of the paper. Contact angle measurements were made to monitor the effect of coating the paper with PEDOT:PSS blends on the hydrophilicity of the paper samples. The amount of PEDOT:PSS deposited in the fiber network was determined using total sulfur analysis. Thus, this study makes use of conventional paper surface treatment as method for achieving bulk conductivity of paper in the semi-conductor range without significantly decreasing the paper strength. / Printed Polymer Electronics