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Orientador: Marcela Rocha de Oliveira Carrilho / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Odontologia de Piracicaba / Made available in DSpace on 2018-08-09T14:06:10Z (GMT). No. of bitstreams: 1 Bail_Michele_M.pdf: 616698 bytes, checksum: d6737bc67e911ea44d56c9e9884e2c55 (MD5) Previous issue date: 2007 / Resumo: O objetivo deste estudo foi avaliar a eficácia de diferentes métodos empregados na eliminação dos solventes incorporados a sistemas de união com características hidrofílicas diferentes. As hipóteses avaliadas consideraram que a eliminação/retenção dos solventes seria dependente: 1) da característica hidrofílica da resina; 2) da técnica e intervalo de tempo empregados na eliminação desses solventes; 3) do tipo de solvente empregado. Três resinas experimentais, R2, R3 e R5, foram formuladas de modo a exibirem características hidrofílicas distintas, dadas pela seleção e proporcionamento de monômeros, comumente empregados na odontologia. A resina R2 era a menos hidrofílica e R5 a mais hidrofílica. Acetona ou etanol foram adicionados a cada resina numa proporção de 50% (em peso). A eliminação dos solventes foi verificada por método gravimétrico, aplicado antes e após a realização dos seguintes tratamentos: 1) jato de ar à temperatura ambiente (JAAmb) por 15s; 2) JAAmb por 30s; 3) JAAmb por 60s; 4) jato de ar aquecido (JAAq) por 15s; 5) JAAq por 30s ou 6) JAAq por 60s. Os dados foram analisados por análise de variância e teste de Bonferroni (a =0,05). Nenhum tratamento eliminou completamente o solvente incorporado às resinas. Maior eliminação do solvente foi verificada para a resina menos hidrofílica R2, sendo que, para maioria das condições avaliadas: R2 > R3 e R2 > R5 (p<0,05). Quanto maior tempo de aplicação dos métodos de evaporação, maior a eliminação do solvente, sendo que aos 60s o percentual de massa perdida foi significativamente maior do que aos 15s (p<0,05). Aplicação do JAAq resultou, em geral, na maior eliminação de solvente quando comparado ao JAAmb (p<0,05). Não houve diferença na capacidade de evaporação dos solventes, acetona e etanol (p>0,05). A eliminação de solventes em adesivos mais hidrofílicos pode ser favorecida adotando se períodos de evaporação mais longos do que os indicados pelos fabricantes e aplicando-se jato de ar aquecido / Abstract: The aim of the present study was to evaluate the ability of different methods to eliminate the solvents incorporated into experimental adhesives with different degree of hydrophilicity. The anticipated hypotheses considered that the elimination/retention of the organic solvents would be dependent on: 1) the hydrophilic features of the experimental resins; 2) the method and time employed to eliminate these solvents; 3) the sort of solvent incorporated into the resin. A series of resin comonomers were blended to create three experimental adhesive resins, R2, R3 and R5, with an increasing degree of hydrophilicity. Resin R2 is the most hydrophobic and R5 is the most hydrophilic. The solvents, acetone and ethanol, were added to each experimental resin in a proportion of 50 wt%, generating six different mixtures. The elimination of these solvents was verified by means a gravimetric method applied before and after the following treatments: 1) application of an air-drying at room temperature for 15 s (ART); 2) ART for 30s; 3) ART for 60s; 4) application of heat-air drying (AH - 40 ± 1°C) for 15s; 5) AH for 30s or 6) AH for 60s. Data were analyzed by ANOVA and Bonferroni¿s test (a =0,05). None of the treatments was able to eliminate completely the solvent incorporated into the experimental resins. The highest elimination of solvent was observed for the resin R2, being that for most of conditions: R2 > R3 and R2 > R5 (p<0.05). The percentage of solvent evaporation increased proportionally with the increase of the time of the air-drying application, being significantly higher in the 60s when compared to 15s (p<0.05). In general, the application of the AH resulted in higher elimination of the solvent when compared to that obtained by the application of the ART (p<0.05). The solvent elimination, in general, did not depend on the sort of the solvent incorporated into the resin (p>0.05). The elimination of solvents from hydrophilic resins can be favored by extending the time for solvent evaporation and applying heat-air drying / Mestrado / Materiais Dentarios / Mestre em Materiais Dentários

Orientadores: Maria Regina Wolf Maciel, Patrícia Fazzio Martins Martinez / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Química / Made available in DSpace on 2018-08-26T01:57:05Z (GMT). No. of bitstreams: 1 Medeiros_HeloisaHelenaBerredoReisde_D.pdf: 2926658 bytes, checksum: ecdad0019abf8c59be4ebbda4314ac06 (MD5) Previous issue date: 2014 / Resumo: O Brasil é o maior produtor mundial de laranjas, sendo também considerado um grande produtor e exportador mundial do óleo de laranja. Óleo de laranja doce, um importante subproduto gerado a partir da produção de suco de laranja, é constituído por aproximadamente 400 compostos, dentre os quais, destacam-se as classes de terpenos, oxigenados e flavonoides. Essas classes de compostos apresentam elevado potencial para as indústrias alimentícia, cosmética, farmacêutica e química. O fracionamento deste óleo tem recebido grande atenção da comunidade científica e industrial devido à instabilidade de determinados componentes. Neste trabalho, a separação e concentração dos componentes limoneno, valenceno, decanal, tangeritina e nobiletina foram realizadas utilizando-se um sistema híbrido de evaporação a pressões de 2 e 20 mbar. Três frações resultantes do sistema foram obtidas, são elas: destilado, lateral e resíduo. Através de um planejamento experimental do tipo composto central, observou-se que a temperatura do evaporador é a variável que tem maior influência nos resultados. As maiores concentrações de limoneno foram encontradas nas frações destilado e lateral, chegando-se à concentração de 99,5%. Os compostos valenceno e decanal não foram identificados na fração destilado e suas maiores concentrações estão presentes na fração resíduo. Comportamento semelhante foi observado para os flavonoides tangeritina e nobiletina, os quais foram concentrados na fração resíduo. De acordo com os resultados obtidos neste trabalho, é promissor separar e concentrar os compostos citados acima presentes no óleo de laranja doce utilizando um sistema híbrido de evaporação / Abstract: Brazil is the world¿s largest orange producer, and is also considered a major producer and exporter of orange oil. Sweet orange oil, an important by-product generated from the production of orange juice, consists of approximately 400 compounds, among which stand out the classes of terpenes, oxygenated and flavonoids. These classes of compounds have high potential for the food, cosmetic, pharmaceutical and chemical industries. Fractionation of this oil has received great attention of the scientific and industrial community due to the intability of certain components. In this work, the separation and concentration of the components limonene, valencene, decanal, tangeritin and nobiletin were performed using a hybrid system of evaporation at pressures from 2 and 20 mbar. Three fractions of the resulting system were obtained, they are: distillate, side and residue. Through an experimental design of the central composite type, it is observed that the evaporator temperature is the variable that has the greatest influence on the results. The highest concentrations of limonene were found in the distillate and side fractions, reaching to the concentration of 99.5%. The valencene and decanal compounds were not identified in the distillate fraction and its highest concentrations are present in the residue fraction. Similar behavior eas observed for tangeritin and nobiletin flavonoids, which are concentrated in the residue fraction. According to the results obtained in this study it is promising to separate and concentrate the compounds mentioned above present in sweet orange oil using a hybrid system of evaporation / Doutorado / Desenvolvimento de Processos Químicos / Doutora em Engenharia Quimica

8 pp. / Reviewed 2/2017; Originally Published 2000 / El manejo apropiado del riego requiere la evaluación de parte del agricultor de sus necesidades de riego en base a medidas de varios parámetros físicos del suelo. Algunos productores utilizan equipo sofisticado mientras que otros se basan en métodos empíricos o en el sentido común. Cualquiera que sea el método usado, cada uno tiene sus propios méritos y limitaciones. El agricultor generalmente se hace dos preguntas al desarrollar una estrategia para el manejo del riego: “¿Cuándo regar?” y “¿Cuánta agua aplicar?”. Este boletín responde a la pregunta CUÁNDO. Reviewed 2/2017; Originally Published 09/2010.

Recent droughts in South Africa have highlighted the vulnerability of the economy to water restrictions. However, the degree of surface aridity in southern Africa is not only a function of precipitation, but also one of evaporation. The quantitative assessment of evaporative loss is important since it is a major component of the water budget. For example, in southern Africa, evaporation accounts for 79.5% of the hydrological water budget. As the cost of water resource development increases, so there has been an increasing demand for hydrological modelling to optimise project planning. Reliable estimates of evaporation are essential to significant improvements in the practice of hydrology and particularly in a country like South Africa which is prone to the adverse effects of drought. It is difficult to adequately measure potential evaporation over an area as large and as sparsely populated as southern Africa. Despite the research that has been undertaken to estimate evaporation from related meteorological and physical variables, generally, the estimation of evaporation in southern Africa has been unsatisfactory. There are a number of methods for estimating potential evaporation. However, a major problem tends to be the incompatibility between the data requirements of some of the more physically-based models, and the actual data that is available and collected on a routine basis at a sufficient number of stations. In existing water resources estimation models, evaporation is often incorporated as a time series input of pan evaporation, using daily or monthly values. The lack of a nearby record of pan evaporation often necessitates the use of published regionalised mean monthly pan values. This technique of using the mean monthly evaporation values in water resources estimation models tends to overestimate or underestimate the actual evaporation that is occurring, depending on the actual amount of rain occurring in a specific month. This is because no attempt has been made to correct these mean evaporation values for the amount of rainfall that occurs in a specific month, in a specific region. The regional rainfall/evaporation relationships (that vary spatially and temporally) are not taken into account. A need was identified for an assessment of the value of grouping data by rainfall as a better tool for estimating evaporation. Here, the monthly evaporation and the mean monthly evaporation for a specific rainfall group category will be estimated using daily data. Due to data availability, the most appropriate time scale to use is one day. Therefore, in this study an attempt has been made to relate rainfall amounts to evaporation values and to develop rainfall/evaporation relationships, identifying variations by season and region. It is important to identify and quantify these relationships and assess the possibility of incorporating these variations into existing Water Resource Estimation Models. The ability to derive and develop meaningful relationships between daily rainfall and daily evaporation for each season, and for a number of sites considered representative of the climatological zones for southern Africa was assessed. The first approach was to compare daily evaporation plotted against daily rainfall, and in the process develop a quantitative rainfall/evaporation relationship. Unfortunately, no direct linear relationships were identified. The second approach was to test the performance of the water resource estimation model using the following possible choices, (i) a real daily input (COREVAP1) - here the estimated monthly evaporation is the sum of the product number of days within each month * mean daily evaporation for each specified raingroup category, (ii) a distributed mean monthly input (COREVAP2) - here evaporation is estimated using a random sampling procedure to draw samples from a restricted part of the daily evaporation distribution for each raingroup and is defined by the mean and standard deviation, and (iii) a distributed mean monthly input and correction (COREVAP3) - here samples are drawn from the full distribution of daily evaporation for each raingroup category. The performance of the COREVAP programs was analyzed in terms of the improvement effected by estimating evaporation using the mean monthly evaporation regardless of rain. COREVAP1 produced the best simulations of monthly evaporation. This was expected as the program uses the straight-forward mean evaporation value multiplied by the number of days to simulate the monthly evaporation values. However, the COREVAP programs did not perform well when using the monthly evaporation data based on daily infilled values using the transformed parameters. Any regionalisation of parameter files would mean that a range of parameters in a region would now be represented by a single value. The need to assess the effect of this change from a regional range of values to a single representative value was identified. This was done by conducting a sensitivity analysis, in terms of what effect a percentage increase or decrease in the lambda, mean evaporation and mean rainfall values would have on the resultant simulated monthly evaporation and coefficient of efficiency values. A sensitivity analysis was conducted on COREVAP1 to determine which parameters of the model had the greatest influence on the simulations. This was done with reference to the percentage error of monthly evaporation and the monthly and accumulative coefficient of efficiency values. Generally, the percentage increase/decrease in mean evaporation values that are acceptable for the representative stations are low. In contrast, fairly high percentage changes in mean rainfall values are tolerated. The objective of the regionalisation of parameters was to determine whether general characteristics can be applied to some stations that are significantly different compared to other stations, so that the stations may be combined to represent a separate region. The demarcation of regions was conducted on the basis of the regional relative mean evaporation values (per raingroup, per season), the daily mean evaporation values per month and the average number of days within each raingroup, per season. Intra-station and inter-region variability was analysed using the Kruskal-Wallis H test and the Friedman Fr test. The regional parameters were then used as input into the COREVAP programs and the simulation results were analysed in terms of whether the simulations still produce positive accumulative coefficient of efficiency values. The results obtained when substituting the regional parameters were not good. Based on these results, it has been concluded that the hypothesis that grouping data by rainfall may be a better tool for estimating evaporation compared to simply using the mean monthly evaporation, may be rejected.

With the increasing pressure of providing reliable potable water in a sustainable way, it is important to understand water phase change phenomena (condensation and evaporation) as the water phase change is involved in many processes such as membrane distillation and solar still which can be a feasible choice of supplementing the present potable water access. In the present thesis, we first elucidate the role of wettability of water condensation substrate by combining the droplet growth dynamics and droplet population evolution. The results show that wettability has a negligible effect on water condensation rate in an atmospheric environment. After confirming the role of substrate wettability, we provide a quantitative analysis of the effect of substrate geometry on water condensation in the atmospheric environment. The analysis can help to predict the efficiency of water condensation rate with a given substrate of a certain geometry with the aid of computational simulation tools. The results show that water condensation can be increased by 40% by rationally designing the geometry of the condensation surface. However, the condensation rate in the atmospheric environment is relatively slow due to the presence of non-condensable gas. In order to increase the condensation rate, a relatively pure vapor environment is desired, in which condensed water will be the major heat transfer barrier. Coalescence induced jumping of condensed droplets on superhydrophobic surfaces is an interesting phenomenon to help faster removal of condensed droplets. However, it is still not clear how to optimize the overall heat transfer efficiency by condensation on such surfaces. We observed an interesting phenomenon on a superhydrophobic nano-cones array, on which water preferentially condenses within larger cavities among the nanocones. Droplets growing form larger cavities have larger growth rate. This finding can possibly provide a solution to optimizing heat transfer efficiency. Finally, a nylon-carbon black composite is prepared by electrospinning to enhance water evaporation under solar radiation. The composite shows an interesting light absorption property. In a wet state, the composite can absorb around 94% of the incident sunlight. The composite also shows strong mechanical and chemical stability. Thus, the composite is considered to be a practical candidate to be applied in the solar distillation process.

京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第22440号 / 工博第4701号 / 新制||工||1734(附属図書館) / 京都大学大学院工学研究科原子核工学専攻 / (主査)教授 横峯 健彦, 教授 佐々木 隆之, 教授 鈴木 基史 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM

Repellents play a key role in preventing mosquito-borne diseases such as malaria by reducing human-vector contact. The general mechanism of action relies on providing a repelling vapour around the applied area on the skin. Thus, the proper evaporation rate and consistency of the composition of the released vapour are factors determining the performance of repellent formulations. The formulation should evaporate fast enough to provide a sufficient level of repellence during its life time. However, if evaporation proceeds too fast, then it will be depleted rapidly so that activity is lost within a short period of time, which makes the repellent inefficient. Several controlled-release approaches have been developed to improve both the protection time and level. However, these techniques have inherent drawbacks from the industrial point of view. Moreover, these techniques mostly focus only on reducing the release rate, while the consistency of the vapour composition has not been addressed. In the present study, a novel approach towards controlling the evaporation behaviour of repellents is proposed. It is based on engineering the molecular interactions in order to design negative pseudo-azeotrope formulations. Negative pseudo-azeotrope mixtures are less volatile than the pure parent components and they do not undergo separation during evaporation. The feasibility of the idea was investigated by studying the molecular structure of generally available repellents. Among known molecular interactions, hydrogen bonding has the most likely impact on the formation of azeotropes and in particular pseudo-azeotropes. Thus, established repellents were classified based on their chemical structures and their capability to take part in hydrogen bonding. Next, a simple spectroscopic method for anticipating pseudoazeotropes formation was developed. Binary compositions of nonanoic acid and ethyl butylacetylaminopropionate (IR3535) showed a potential for forming pseudo-azeotrope mixtures. Hence R3535 and nonanoic acid were selected as model compounds to test the hypothesis. An experimental technique to confirm pseudo-azeotrope formation and to locate the composition of the probable pseudo-azeotrope point was required. To this end, an oven test was designed. The temporal mass loss, under an isothermal program, of a series of evaporating mixtures was measured. Simultaneously, the Fourier transform infrared (FTIR) spectra of the liquid remaining was recorded. Inverse analysis techniques were used to determine the composition of remaining liquid mixtures from the recorded FTIR spectra. The oven tests revealed that, as vaporisation progressed, the composition of the liquid remaining and the emitted vapour converged to a fixed IR3535 content of ca. 75 mol%. Mixtures close to this composition also featured the lowest volatility. Oven test also showed that the composition of the liquid mixtures diverged from the fixed IR3535 content of ca. 10 mol%. Mixtures close to this composition featured the highest volatility. These observations showed that IR3535 and nonanoic acid forms two pseudo-azeotrope compositions, i.e. a negative pseudo-azeotrope at an IR3535 content of ca. 75 mol%, and a positive pseudo-azeotrope at IR3535 content of ca. 10 mol%. Thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) were applied to check these results. TGA confirmed that the negative pseudo-azeotrope mixture is less volatile while the positive pseudo-azeotrope is more volatile than the parent compounds. The DSC results revealed that in comparison with the pure compounds, negative pseudo-azeotrope had a lower boiling point onset while the positive pseudo-azeotrope had a higher boiling point. Although negative pseudo-azeotrope repellent formulations have the desired lower constant release rate, their repellent activity needed to be tested. This is due to the fact that mixing the ingredients to formulate a negative pseudo-azeotrope results in interactions among the components. As a consequence, the inherent repellence effect of the compounds might have been impaired in the mixture. The modified arm-in-cage test was used to test the repellence of the controlled-release repellent formulation i.e. the negative pseudo-azeotrope of the IR3535 + nonanoic acid system. Results showed that the mixture featured improved performance with respect to both repellence efficacy and persistence. Moreover, the negative pseudo-azeotrope also exhibited a knock down effect, even resulting in mortality of most of the test mosquitoes. The presence of two pseudo-azeotrope points at different composition in the IR3535 + nonanoic acid system is a rare occurrence, analogous to double azeotropy. Thus, molecular simulation techniques were used to explore the nature of system and the interactions responsible for this unique behaviour. Gibbs-Monte Carlo simulation results suggest that variations in the sizes of the molecular clusters present in the liquid at various compositions might be responsible. They revealed that IR3535 and nonanoic acid in neat form are both highly structured liquids. The break-down in the structure of IR3535 at high concentrations of the acid may be the origin of increased evaporation rate and formation of the positive pseudo-azeotrope. On the other hand, negative pseudo-azeotrope may be resulted from formation of bulkier clusters at the ration of 3:1 (IR3535: nonanoic acid). / Thesis (PhD (Chemical Technology))--University of Pretoria, 2016. / English / PhD (Chemical Technology) / Unrestricted

Master thesis is focused on design of ground heat pump with direct evaporation. First part is dedicated to description of heat pump technology, cooling circulation and sources of low-potential heat. Heat pump ground-water, its main components, classification of refridgerant and systems of direct evaporation are all described in the second part. The last part consists of design of each individual component of heat pump and solution of ground heat exchanger for direct evaporation of refridgerant.