Embora o uso de etanol como combustível venha aumentando no Brasil e em diversos países, há uma grande escassez de dados relacionados à abundância desse álcool e de espécies orgânicas correlatas na atmosfera. O estudo temporal do comportamento do etanol em água de chuva no Brasil é pioneiro, e serve de base para melhor compreender as alterações que possam ocorrer na atmosfera devido ao aumento do uso desse combustível. Neste trabalho foi desenvolvido um novo método utilizando headspace GC-FID para a determinação simultânea de acetaldeído (AA), acetona (AC), metanol (MeOH) e etanol (EtOH), em concentrações ambientalmente relevantes em águas naturais. O método é mais simples do que aqueles apresentados na literatura, robusto e de custo relativamente baixo. O método apresentou boa recuperação, precisão, e sua exatidão foi comprovada pela forte correlação com o método que utiliza HPLC, e que já é bem estabelecido. A concentração de etanol foi determinada em amostras de água de chuva de Ribeirão Preto coletadas de 2012 a 2016 (n = 186). A média ponderada pelo volume (MPV) foi de 5,28 ± 0,49 µmol L-1, que é próxima da concentração esperada no equilíbrio entre a fase gasosa e aquosa. Esse valor de etanol é cerca de 28 vezes maior do que a média encontrada na cidade de Wilmington (EUA), refletindo o elevado uso de etanol combustível no Brasil. As concentrações médias anuais de etanol na chuva nos mais de 4 anos de estudo variaram pouco, e também não apresentaram diferenças significativas de acordo com a estação do ano, sazonalidade das atividades agrícolas, ou com a direção das massas de ar. Para as amostras de água de chuva coletadas de fevereiro a dezembro de 2016 a concentração MPV das espécies analisadas foram: 0,84 ± 0,12 µmol L-1 AA (n= 62); 0,70 ± 0,08 µmol L-1 AC (n = 59);10,9 ± 1,19 µmol L-1 MeOH (n = 62), 15,8 ± 1,64 µmol L-1 ácido fórmico (n = 67); e 9,76 ± 0,95 µmol L-1 ácido acético (n = 67). A massa média de carbono orgânico identificado nas amostras representou cerca de 20% do total de carbono orgânico dissolvido (COD) na água de chuva. O fluxo estimado de carbono orgânico por deposição úmida foi de 5,1 g C m-2 ano-1, sendo 1,0 g C m-2 ano-1identificados neste trabalho. Além da emissão veicular, uma importante fonte de COD para a atmosfera é a queima de biomassa, que ainda ocorre com frequência no estado. As ferramentas estatísticas aqui utilizadas considerando as espécies orgânicas identificadas juntamente com outras espécies inorgânicas majoritárias, não permitiram separar claramente as fontes predominantes de emissão na região. Isso deve ocorrer porque a emissão veicular durante todo o ano é predominante com relação às possíveis emissões biogênicas e por queima de biomassa. A exposição de amostras de água de chuva à irradiação com luz solar artificial mostrou que houve perda de EtOH e formação de AA, porém os processos não ocorreram em proporção estequiométrica, e nem na mesma taxa. No caso do MeOH e formaldeído, a formação e perda dessas espécies ocorreram de forma errática. A ausência de uma tendência clara nas transformações fotoquímicas dos álcoois reflete a complexidade da matriz e das reações envolvidas na atmosfera. / Although there has been a dramatic increase on the use of ethanol fuel in Brazil and in several other countries, there is a great lack of data related to the abundance of ethanol and associated organic species in the atmosphere. The temporal study of the behavior of ethanol in rainwater in Brazil is pioneer, and may serve as a basis to better understand the changes that occur in the atmosphere due to the increasing use of this fuel. This work presents a new headspace GC-FID method to simultaneously determine acetaldehyde (AA), acetone (AC), methanol (MeOH) and ethanol (EtOH) at environmentally relevant concentrations in the atmosphere and in a variety of natural waters. The method is simpler than those presented in the literature, robust and relatively low-cost. The method presented good recovery, precision and good agreement with a HPLC method for determination of acetaldehyde, methanol, and ethanol, which endorsed the accuracy of the proposed method. The ethanol concentration was determined in rainwater samples from Ribeirão Preto from 2012 to 2016 (n = 186). The volume-weighted mean (VWM) was 5.28 ± 0.49 mol L-1, which is close to the expected concentration at the equilibrium between the gas and aqueous phases. The ethanol value is about 28 times higher than the average found in the city of Wilmington (USA), reflecting the high use of ethanol fuel in Brazil. The annual mean concentrations of ethanol in rainwater samples over 4 years of monitoring varied little, and also did not show significant differences according to the season, agricultural activities, or the direction of the air masses. For the rainwater samples collected from February to December 2016 the VWM concentration of the other analyzed species were: 0.84 ± 0.12 mol L-1 AA (n = 62); 0.70 ± 0.08 mol L-1 AC (n = 59), 10.9 ± 1.19 mol L-1MeOH (n = 62), 15.8 ± 1.64 mol L-1formic acid (n = 67); and 9.76 ± 0.95 mol L-1 acetic acid (n = 67). The identified organic carbon average mass in the samples represented about 20% of the total dissolved organic carbon (DOC) in rainwater. The estimated flux of organic carbon by wet deposition was 5.1 g C m-2 year-1, being 1.0 g C m-2 year-1 identified in this work. In addition to the vehicular emission, an important source of DOC to the atmosphere is the biomass burning, which still occurs frequently in the state. The statistical tools used here, considering the organic species identified together with other major inorganic species, did not allow to clearly separate the predominant emission sources in the region. This may occur because the year-round vehicular emission is predominant in relation to the possible biogenic and by biomass burning emissions. Exposure of rainwater samples to irradiation with artificial sunlight showed that there was loss of EtOH and formation of AA, but the processes neither occurred in stoichiometric proportion, nor at the same rate. In the case of MeOH and formaldehyde, the formation and loss of these species occurred erratically. The absence of a clear trend in the photochemical transformations of alcohols reflects the complexity of the matrix and the reactions involved in the atmosphere.

A determinação de valores de referência de alguns xenobióticos naturalmente existentes no organismo é importante na biomonitorização, para comparação de níveis encontrados na população exposta com os da população de referência. A acetona é um solvente muito popular, utilizado em vários ramos da indústria e em laboratórios químicos. O isopropanol é um solvente largamente utilizado em indústrias, laboratórios e está presente em vários produtos domésticos. Este solvente é biotransformado no organismo humano, tendo como principal metabólito a acetona. A acetona em urina (AcU) é o bioindicador mais usado para avaliar a exposição de trabalhadores expostos a acetona e ao isopropanol. Como também é encontrada em pessoas não expostas ocupacionalmente a estes solventes, o objetivo deste trabalho foi verificar os níveis basais de AcU e a possível influência de fatores individuais nestes níveis. A população de referência foi constituída por 207 indivíduos (91 homens e 116 mulheres, com idades entre 18 e 80 anos). A AcU foi determinada por headspace/cromatografia em fase gasosa/DIC. O método mostrou linearidade de 0,1 a 5,0 mg/L; o limite de detecção e de quantificação de 0,1 mglL; precisão intra-ensaio, entre 4 e 5% e inter ensaio, entre 5,2 e 8,8% (urina sem adição e fortificada com 1,0 e 3,0 mgIL de acetona). Para a população total, os valores de referência encontrados foram: média (&#177;DP) de 1,12 (&#177;0,47) mgIL; mediana de 1,04 mgIL; média geométrica de 1,03 mglL; intervalo de confiança 95% entre 0,98-1,26 mglL e valor superior de referência (média + 2DP) de 2,06 mgIL. Devido ao fato da distribuição dos valores de AcU (mgIL) não ser Gaussiana, optou-se por uma transformação dos valores (Iog AcU) que aproximou os dados da distribuição normal ( W = 0,98532, P < 0,7000). A população selecionada demonstrou ser saudável e adequada ao estudo; o sexo e a ingestão de bebidas alcoólicas parecem afetar os teores de acetona urinária, enquanto a idade e o uso de tabaco não mostraram este efeito. / The determination of reference values of some xenobiotics is important for the biomonitoring, to compare the concentration in the exposed and the general population. The acetone is a very popular solvent, that is used in a large number of industries and laboratories. Isopropanol is used in industries, laboratories and cosmetic products. In the human body, this solvent is metabolized and the most important product is acetone. Acetone in urine (AcU) is the most used biomarker to monitore workers exposed to acetone/isopropanol. This substance is also found in non-exposed people, so, the main objective of this work was to verify the basal levels of AcU and if there are some factors that have influence on these levels. 207 volunteers were studied (91 men and 116 women, and the ages between 18-80 years). The AcU was determinated by headspace/gas chromatography/ FID. The method showed linearity between 0.1-5.0 mg/L; limit of detection (LOD) and limit of quantification of 0.1 mglL; intra-assay precision, between 4 and 5%; inter-assay precision, between 5.2 and 8.8% (urine without addition, and spiked 1.0 and 3.0 mg/L of acetone). In the total population, the reference values obtained were: mean (&#177;SD) 1.12 (&#177; 0.47) mg/L; median 1.04 mg/L; geometric mean 1.03 mg/L; 95% confidence range between 0.98-1.26 mg/L and upper reference value (mean + 2 SD) of 2.06 mg/L. The values distribution wasn\'t \"normal\", therefore, the ,transformation of the values was necessary (109 AcU). Sex and alcohol intake showed significant influence on the concentration of acetone in urine. No interference was verified for smoking or the age of the volunteers.

This study applied sputtering technology to prepare composite film photocatalyst TiO2/ITO for investigating the decomposition efficiency of acetone using composite TiO2/ITO made by single- and multi-layer processes. The influences of operating parameters, including sputtering operating parameters and photocatalytic operating parameters, on the decomposition efficiency of acetone were further investigated. Operating parameters investigated for the sputtering process included oxygen to argon ratio (O2/Ar), temperature, substrate, sputtering dutation, and sputtering layers, while operating parameters investigated for the photocatalytic decomposition of acetone included light wavelength, H2O concentration, O2 concentration, initial acetone concentration, and the type of photocatalysts. In the experiments, acetone was degraded by the composite film photocatalyst TiO2/ITO in a self-designed batch photocatalytic reactor. Operating parameters included light wavelength (350~400 nm, 435~500 nm, 506~600 nm), the type of photocatalysts (single-layer film photocatalyst TiO2/ITO with the thickness of 355.3, 396.6, 437.5, 487.5, and 637.5 nm; double- and triple-layer TiO2/ITO), H2O concentration (0, 50, 100, 200, and 300 ppm). The incident light with different wavelength irradiated with three 15-W lamps of near UV light or LED lamps of blue and green lights placed on the top of the photocatalytic reactor. Acetone was injected into the reactor by using a gasket syringe and vaporized for further photocatalytic degradation on the film photocatalyst TiO2/ITO placed at the bottom of the reactor. Air samples were taken to analyze acetone concentration with a GC/FID. The composite film photocatalyst TiO2/ITO was mainly composed of anatase with a few rutile. The thicknesses of the single- and IV double-layer film photocatalyst with the thickness of 473.5 nm and 506.0 nm, respectively. Experimental results indicated that the highest decomposition efficiency of acetone was obtained by using TiO2/ITO, followed by TiO2/ground glass and TiO2/glass. The highest decomposition efficiency of acetone was observed by using TiO2/ITO at 50¢XC, 20% O2, and 100 ppm H2O. In the kinetic model, the acetone decomposition of single-layer TiO2/ITO was zero-order reaction. The acetone decomposition of double-layer TiO2/ITO in high initial acetone concentration was zero-order reaction, while that in low initial acetone concentration was first-order reaction. Thus, the decomposition of acetone exerted by TiO2 film photocatalyst can be enhanced efficiently by ITO. Under the incidence of blue light, the reaction rate of acetone decomposition were 2.353¡Ñ10-5 and 3.478¡Ñ10-5 £gmole/cm2-s for using single- and double-layer TiO2/ITO, respectively. Finally, a bimolecular Langmuir-Hinshelwood (L-H) kinetic model was applied to simulate the influences of initial acetone concentration, temperature, and relative humidity on the promotion and inhibition for the photocatalytic degradation of acetone. This study revealed that the L-H kinetic model could successfully simulate the photocatalytic reaction rate of acetone.

The study combined photoelectrocatalytic technology (PEC) with electrical glassfiber filter (EGF) to decompose volatile organic compounds (VOCs). External electrical voltage was applied to retard the recombination of electron-electron hole pairs and increase the surface temperature of the photocatalysts coated on the electrical glassfiber filter, which could further decompose VOCs more effectively via photoelectrocatalytic technology. Acetone was selected as the gasous pollutant for this particular study. A commercial TiO2 photocatalyst (AG-160) was coated on GFF via impregnation to decompose acetone in a batch PEC reactor. Operation parameters investigated in this study included acetone concentration (50~400 ppm), electrical voltage (0~6,500V), water content (0~20,000 ppm), reaction temperature (40¢J~80¢J).The incident UV light of 365 nm wavelength was irradiated by three 15-wat low pressure mercury lamps (£f=365 nm) placing above the batch PEC reactor. The TiO2-coated EGF was placed at the center of the batch PEC reactor. Acetone was injected into the reactor by a gasket syringe to conduct the PEC decomposition test. Acetone was analyzed quantitatively by a gas chromatography with a flame ionization detector (GC/FID). Finally, a Langmuir-Hinshelwood kinetic (L-H) model was proposed to simulate the PEC reaction rate of acetone. Experimental results showed that the size range of the self-produced nano-sized photocatalyst prepared by sol-gel was 35~50 nm. Three duplicate tests of PC and PEC degradation of acetone indicated that TiO2 was not deactivated during the PC and PCE reactions, hence TiO2 can be reused in the experiments. Results obtained from the PC and PEC degradation experiments indicated that the PEC reaction rate was higher than the PC reaction rate.The PEC reaction rate increased with applied electrical voltage, and the highest decomposition efficiency occurred at 6,500 V. Electrical field generated by the differences of electrical voltage can effectively enhance the oxidation capability of TiO2 since electron (e-) can be conducted to retard the recombination of electron and electron hole pairs. Both PC and PEC technologies could be used to decompose acetone. Among them, PEC had highter decomposition efficiency of acetone than PC up to 34%. Rsults obtained from the operation parameter tests reaveled that raising electrical voltage could enhance the decomposition efficiency of acetone only for electrical voltages above 2,000 V. However, the decomposition efficiency of acetone tended to level off as electrical voltage became higher. Zero-order reaction rate of the PEC reaction was observed for initial acetone concentration of 100~400 ppm, while the PEC reaction decreased gradually for initial acetone concentration reaction below 100 ppm. It revealed that the PEC reaction was pseudo ozero-order for initial acetone concentration of 100~400 ppm, and pseudo first-order reaction for acetone concentration below 100 ppm. Additionally, the PC reaction rate increased with temperature at 45-80¢J. However the PEC reaction rate increased with temperature at 45-60¢J, and decreased with temperature at 60-80¢J. An adsorptive competition between acetone and water molecules at the active sites over TiO2 surface caused either promotion or inhibition of TiO2 decomposition depending on moisture content . For the PC and PEC reactions, the optimum operating condition of water vapor concentration was 10,000 ppm, but inhibition occurred when the water vapor concentration increased up to 20,000 ppm. Finally, the Langmuir-Hinshelwood kinetic model was applied to investiage the influences of reaction temperature, initial concentration of acetone, and water content on the photoelectrocatalytic reaction rate of acetone. Model simulation results showed that photoelectrocatalytic reaction rate constant of acetone(kLH) and adsorptive equilibrium constant(KA) increased with electrical voltage and acetone initial concentration. This study sevealed that experimental and simulated results were in good agreement. Thus, PEC reaction rate of acetone on the surface of TiO2 can be also succesfully simulated by the L-H kinetic model.

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No description available.

The work presented in this thesis describes an investigation into the properties and behaviour of a new class of nonlinear optical organic chromophores. This study contributes to the optimisation of nonlinear optical molecules through an improved understanding of the relationships between the molecular nonlinear optical properties and the measured macroscopic quantities. A series of highly dipolar non-linear optical chromophores with absorption typically in the range of 350-500 nm have been synthesised by the reactions of amines with tetracyanoquinodimethane (TCNQ). One of the advantages of these materials is the large molecular figure of merit (μβ where μ is the molecular dipole moment and P is the second order polarisability), which theoretically allows large nonlinear optical coefficients to be obtained. The molecular dipole moments of these chromophores were determined both experimentally and theoretically, and were found to agree. The nonlinear optical properties of these compounds in solution were studied using an electric field induced second harmonic generation (EFISH) technique. The measurements of μβ at 1064 nm and 1907 nm in chloroform and acetone are presented. Moderate μβ values were obtained but β is found to be unexpectedly small in chloroform and shows unusual dispersion characteristics in this solvent compared to acetone. Further concentration investigations revealed features that suggest the presence of aggregates within solution. Optical spectroscopy measurements provide evidence of new species whose presence and conformation were found to be solvent-dependent. The results of this work highlight the need for an entire concentration range to be studied if accurate determination of molecular properties of highly dipolar molecules is required. Guest-host polymer films of these materials have been corona poled using a constant current corona triode. Detailed characterisation studies of the second order nonlinearities using second harmonic generation (SHG) were compared to a less dipolar molecule. These investigations showed that the highly dipolar TCNQ derivatives show severe aggregation within the polymer films. The magnitude of the SHG that can be obtained from such systems is therefore limited by this aggregation.

abstract: In the search for chemical biosensors designed for patient-based physiological applications, non-invasive diagnostic approaches continue to have value. The work described in this thesis builds upon previous breath analysis studies. In particular, it seeks to assess the adsorptive mechanisms active in both acetone and ethanol biosensors designed for breath analysis. The thermoelectric biosensors under investigation were constructed using a thermopile for transduction and four different materials for biorecognition. The analytes, acetone and ethanol, were evaluated under dry-air and humidified-air conditions. The biosensor response to acetone concentration was found to be both repeatable and linear, while the sensor response to ethanol presence was also found to be repeatable. The different biorecognition materials produced discernible thermoelectric responses that were characteristic for each analyte. The sensor output data is presented in this report. Additionally, the results were evaluated against a mathematical model for further analysis. Ultimately, a thermoelectric biosensor based upon adsorption chemistry was developed and characterized. Additional work is needed to characterize the physicochemical action mechanism. / Dissertation/Thesis / M.S. Bioengineering 2011

Submitted by Emanuel Varela Cardoso (emanuel.varela@ufcg.edu.br) on 2018-10-09T20:31:46Z No. of bitstreams: 1 CHRISTIAN EIKE PRECKER – DISSERTAÇÃO (PPGFísica) 2013.pdf: 1407137 bytes, checksum: 7c5cdef4ee790652d5d7b4f0c648d68a (MD5) / Made available in DSpace on 2018-10-09T20:31:46Z (GMT). No. of bitstreams: 1 CHRISTIAN EIKE PRECKER – DISSERTAÇÃO (PPGFísica) 2013.pdf: 1407137 bytes, checksum: 7c5cdef4ee790652d5d7b4f0c648d68a (MD5) Previous issue date: 2013-07 / Capes / A evolução dinâmica e o mecanismo da corrosão sob tensão fraturante acelerada (accelerated stress corrosion cracking – aSCC) em uma amostra de acrílico (PMMA – poly methyl 2-methylpropenoate) foi explorada quantitativamente na ausência de carga mecânica externa. Uma incomum e rápida propagação de trincas em amostras usinadas deste material foi induzida por solvente, onde estas foram monitoradas por imagens de vídeo de um microscópio. As trincas emanaram de canais fresados na amostra a partir de um breve contato do solvente acetona com a sua superfície. O período da propagação das trincas durou em torno de 1 minuto, compreendendo um comprimento final de 0,2 a 0,3 mm, e uma taxa de crescimento que decai de 5 2 10  para 6 10 m/s. A evolução temporal da trinca concorda com a difusão unidimensional do solvente ao longo da trinca, sobreposto por um campo de tensão residual. Através de birrefringência que foi oticamente registrada, bem como uma simulação da estrutura mecânica foi feita por meio de elementos finitos, identificamos tensão de tração residual (residual tensile stress) na zona da trinca como sendo uma força motriz. O fator de intensidade de tensão residual ΔK foi determinado em 1–2 MPa m1/2. A aSCC no material se origina de uma combinação de tensões residuais, induzida pela fresagem da superfície da amostra; stress que induz uma rápida difusão do solvente acetona no material e uma degradação associada com os parâmetros da estrutura mecânica. / The dynamic evolution and mechanism of accelerated stress corrosion cracking (aSCC) in an acrylic (PMMA–poly methyl 2-methylpropenoate) polymer sample have been exploited quantitatively, in absence of external mechanical load. Unusually fast propagation of solvent induced cracks in micro-machined sections of the material has been monitored by microscopic video imaging of a test device. Crack emanation from milled micro-channels was precisely triggered by brief surface wetting with acetone solvent. The crack propagation period persists over a time span of approximately 1 min, comprises a final crack length of 0.2–0.3 mm, and an associated crack growth rate that decreases from 5 2 10  to 6 10 m/s. The temporal crack evolution scales in accord with 1-dim solvent diffusion along the flaw, superimposed with the residual stress field. Optically recorded birefringence, as well as finite element structure mechanic simulation, identified residual tensile stress in the crack zone as the driving force. The residual stress intensity factor ΔK was determined to 1–2 MPa m1/2. The aSCC (accelerated stress corrosion cracking) in the material originates from a detrimental combination of residual stress, induced by surface milling; stress induced fast diffusion of the acetone solvent into the material and an associated degradation of structure-mechanic parameters.

The aim of this diploma thesis was to evaluate the occurrence of ketones and free fatty acids in milk of high-yielding cows. Ketosis is a very common metabolic disorder in dairy cows resulting in reduced milk production, fertility disturbance and more frequent occurrences of other diseases. Ketosis is not only a serious health problem, but also an economic problem, that can be avoided by balancing the feeding dose respecting the physiological needs of energy delivery after birth and at the beginning of lactation of high-yielding cows. The monitoring was carried out in 2016 at Chyšná, which is one of the centers of Agribusiness Košetice a.s. Owerall were 1407 cows monitored during the 6 utility tests (from January to June 2016). The occurrence of subclinical ketoses was defined by the content of ketones in milk (acetone and beta-hydroxybutyric acid). Critical was the period of the first 12 days of lactation, when the occurence of subclinical ketoses was the highest, the occurence of this disease was lower than in other breeds. At Chyšná breeding, the low incidence of subclinical ketoses is mainly influenced by zootechnical work and by working with the feed consultant and the company for the production of compound feeds. As a precautionary process, regular feed analysis and examination of free fatty acids and ketones in milk can be recommended.