Este trabalho tem por objetivo estudar a molhabilidade e a permeabilidade para quatro espécies de madeiras tropicais (Pinus elliottii, Araucaria angustifolia, Eucalyptus grandis e Eucalyptus citriodora). A molhabilidade é um parâmetro importante para a caracterização de diferentes espécies de madeira e, portanto, depende de fatores como o estado de limpeza da superfície da madeira, orientação das fibras, tipo de amostra (alburno ou cerne), secagem, tratamentos térmicos e químicos, rugosidade superficial, etc. Primeiramente, investigamos a molhabilidade para as quatro espécies tropicais por medida de ângulo de contato aparente para diferentes solventes na superfície da madeira As amostras foram tratadas termicamente no intervalo 100 200º C, por 8h e foi utilizado o método da gota séssil e um goniômeto. Os valores dos ângulos de contato foram maiores para as amostras submetidas aos tratamentos térmicos, indicando um aumento no caráter hidrofóbico da madeira. A técnica de ângulo de contato não foi eficiente para tratamentos térmicos superiores a 200º C, devido a sua degradação. No experimento de permeabilidade foi utilizado um fluxo de ar através das amostras com poros fechados e abertos. Foi verificado um acréscimo de 82 % na vazão para as situações de poros abertos no Eucalyptus citriodora. Nossos resultados permitem detectar mudanças consideráveis na molhabilidade e permeabilidade da madeira, sendo informações valiosas para a conservação e utilização destas madeiras. / This work aims to study wettability and permeability for tropical wood species (Pinus elliotti, Araucaria angustifolia, Eucalyptus grandis and Eucalyptus citriodora).The adhesive wettability is an important parameter for characterizing different wood species and depends on factors such as cleaning state of the wood surface, orientation of the wood fibers, type of sample (sapwood or heartwood), drying, thermal and chemical treatments, surface roughness, etc. First, we investigated the wettability of the four tropical wood species by measuring the apparent contact angles of different solvents on the wood surfaces. The samples were heat treated from 100 to 200 °C for 8 h, and the contact angles measured by the sessile drop method with a home-made goniometer. For samples heat-treated below 200 °C, higher values of contact angles were obtained, indicating a hydrophobic character for thermal treated woods. After this temperature, the wood degradation took place. For permeability experiments, a flow of air was used for wood samples with closed and open pores. An increase of 82% in flow was verified for open pores woods such as Eucalyptus citriodora. Our results allowed us to detect considerable changes on wood wettability and permeability and that are powerful information for conservation and use of these woods.

Si l’eau d’une rivière coule sous l’influence d’une petite pente, une goutte de pluie millimétrique s’accroche généralement à son substrat. Cette thèse considère les problèmes engendrés par cette adhésion liquide-solide à l’aune de l’application culinaire. Nous nous intéressons aux surfaces superhydrophobes dont la chimie et la rugosité rendent ces solides non-adhérents. Par ailleurs, le comportement de ces matériaux en température rend compte de différents domaines d’adhésion. Ces surfaces voient leur adhésion augmenter avec la température lorsque la vapeur se recondense au sein des textures du solide. Mais, à mesure que la température s’élève, des bulles de vapeur se forment et réduisent l’adhésion, jusqu’à l’annuler lorsque le liquide lévite sur un coussin continu de vapeur. Nous décrivons cet état, dit de caléfaction, et notamment l’origine de la température critique pour laquelle ce phénomène apparaît. La superhydrophobie permet de réduire considérablement cette température, dite de Leidenfrost, et de rendre accessible la caléfaction pour des températures typiques de cuisson. Enfin, nous comparons ces résultats aux stratégies de non-adhésion culinaire : à savoir les revêtements hydrophobes et l’utilisation d’huile. Des surfaces mixtes piégeant une fine couche d’huile dans des textures hydrophobes sont ainsi discutées. / Water flows inside a river due to extremely low slopes whereas a millimetric raindrop generally sticks on its substrate. This thesis investigates problematics induced by liquid-solid adhesion as regards the cooking device application. We study superhydrophobic substrate whose both chemistry and roughness promote anti-adhesion. We describe the anti-adhesive behaviour in temperature. First, because of condensation through the porous media, the adhesion rises with temperature before vapour bubbles nucleate below the drop. Then, the production of vapour generates a lack of contact. Thus, adhesion decreases until the liquid levitates on its own vapour. We describe this phenomenon known as the Leidenfrost effect. We especially discuss the critical Leidenfrost temperature and its origin. Superhydrophobic coatings promote Leidenfrost effect at remarkably low temperature close to cooking typical one. Finally, those results are compared to two strategies used in cooking: hydrophobic anti-adhesive coatings and lubrication by oil. Some lubricant-infused substrates are investigated.

The concept of creating heterogeneous structures by nanocasting techniques from a combination of several homogeneous surfactant templated structures to model reservoir rock properties has not been approached prior to this research project, and will be used to test and provide better understanding of gas adsorption theories such as the pore blocking phenomenon (Seaton, 1991). Porous media with controlled pore sizes and geometry can be used to mimic a variety of reservoir rock structures, as it can be engineered to consist of a network of elements which, individually, could have either regular or irregular converging and diverging portions. The restrictions in these elements are called throats, and the bulges pores. Catalysts developed from a range of Nanotechnology applications could be used in down-hole catalytic upgrading of heavy oil. They could also be used as catalyst supports or to analyse the coking performance of catalysts. These studies will highlight the pore structure effects associated with capillary trapping mechanisms in rocks, and potentially allow the manipulation of transport rates of fluids within the pore structure of catalysts. Mercury-injection capillary pressure is typically favoured for geological applications such as inferring the size and sorting of pore throats. The difference between mercury injection and withdrawal curves will be used to provide information on recovery efficiency, and also to investigate pore level heterogeneity. Mercury porosimetry studies are carried out to provide a better understanding of the retraction curve and the mechanisms controlling the extrusion process and subsequently the entrapment of the non-wetting phase. The use of model porous media with controlled pore size and surface chemistry allows these two effects to be de-convolved and studied separately. The nanotechnology techniques employed mean that uncertainty regarding exact pore geometry is alleviated because tight control of pore geometry is possible. Trapping of oil and gas on a microscopic scale in a petroleum reservoir rock is affected by the geometric and topologic properties of the pores, by the properties of the fluids and by properties related to fluid-rock interaction such as wettability. Several distinct mechanisms of trapping may occur during displacement of one fluid by another in a porous media, however in strongly water-wet rocks with large aspect ratios, trapping in individual pores caused by associated restricting throats (may be/is) the most important mechanism of trapping. The results of the proposed research will be both relevant to the Irene Osagie Evbuomwan PhD. Thesis (2009) 9 oil and gas as well as the solid mineral sector for application as catalyst or catalyst supports. By providing a better understanding of the relationship between reservoir rock pore space geometry and surface chemistry on the residual oil levels, a more accurate assessment of the potential of a particular reservoir could be generated. The analysis of gas adsorption/desorption isotherms is widely used for the characterization of porous materials with regard to their surface area, pore size, pore size distribution and porosity, which is important for optimizing their use in many practical applications. Although nitrogen adsorption at liquid nitrogen temperature is considered to be the standard procedure, recent studies clearly reveal that the use of additional probe molecules (e.g. argon, butane, carbon dioxide, water, hydrogen, and hydrocarbons e.g. cyclohexane and ethane) allows not only to check for consistency, but also leads to a more comprehensive and accurate micro/mesopore size analysis of many adsorbents. Furthermore, significant progress has been achieved during recent years with regard to the understanding of the adsorption mechanism of fluids in materials with highly ordered pore structures (e.g., M41S materials, SBA-15). This has led to major improvements in the pore size analysis of nanoporous materials. However, there are still many open questions concerning the phase and sorption behaviour of fluids in more complex pore systems, such as materials of a heterogeneous nature/differing pore structures, which are of interest for practical applications in catalysis, separation, and adsorption. In order to address some of these open questions, we have performed systematic adsorption experiments on novel nanoporous materials with well defined pore structure synthesised within this research and also on commercial porous silicas. The results of this study and experiments allow understanding and separating in detail the influence of phenomena such as, pore blocking, advanced condensation and delayed condensation on adsorption hysteresis and consequently the shape of the adsorption isotherms. The consequences of these results for an accurate and comprehensive pore size analysis of nanomaterials consisting of more complex nanoporous pore networks are also investigated.

A one-dimensional porous media model has been developed to investigate water based fire suppression. The model is for heat and mass transfer in porous materials subjected to external water sprays and radiant heating. In the model, heat transfer inside the material occurs by conduction, convection, and phase change. Mass transfer occurs by gas phase diffusion and convection in the liquid and gas phases. Convective mass fluxes are driven by pressure gradients according to Darcy’s Law. Boundary conditions that are appropriate for a range of cases are presented. The model was used, along with experiments, to investigate two scenarios relevant to water based suppression: spray wetting and radiant heating. Ceramic fiberboard samples were used as a test material. For the wetting tests, the model is shown to be able to reasonably predict the rate of water absorption into the samples. Radiant heating tests were conducted in the cone calorimeter with pre-wetted samples. For the heating tests, the model is shown to reasonably predict the drying behavior that would directly precede an ignition event.

"The temperature dependence of the contact angle of water on graphite, silicon and gold was investigated under various conditions to test the Sharp-Kink Approximation. Despite correctly predicting the contact angle at room temperature, the ideal Sharp-Kink Approximation was not found to accurately describe the contact angle's temperature dependence. The discrepancies from the predicted contact angle were characterized in terms of a correction H(T) to the liquid-solid surface tension. H(T) was found to be linear in temperature and decreasing, and is consistent with electrostatic charge effects."

Chemical and physical interactions play important roles in surface film formation and fluid slip at the fluid-solid interface. It has been shown that the fluid molecules at this solid interface behave differently than the molecules in the bulk. To investigate fluid film formation and the fluid’s transition between bulk and interfacial regions, a dynamic wetting technique is utilized. This technique allows the formation of variable thickness fluid films. When used in conjunction with vibrational spectroscopy and ellipsometry, direct analysis of variable thicknesses films, spanning the bulk to interfacial transition, can be obtained. Film thickness are predicted using the Landau-Levich model and the Lifshitz model, and comparisons generally agree with experimental results. According to hydrodynamic no slip boundary condition, fluid molecules near a solid surface can have no velocity with respect to the solid substrate. Recent theories state more specifically that, if a fluid comes in contact with an ultra-smooth surface (< 5-7 nm RMS roughness), the no slip boundary condition might be violated. We confirmed violation of the no slip boundary condition in two specific cases for fluid layers on SAM-modified substrates. To understand how the fluid/solid properties affect this condition, an acetophenone and bare silver surface was studied. Our results show that the structure and ordering of fluid molecules within these films are highly dependent on the film’s thickness and confinement. Temperature control wetting studies also corroborate with these results showing that as a frozen film of large thickness approaches the melting point, a molecular reorganization occurs creating a crystalline structure before the film melts into an isotropic bulk structure. Structure dependence on alkyl-chain length was then investigated using a series of trialkylamine fluids. Results show significant changes in the vibrational profile as a function of film thicknesses and rotational velocity as the alkyl-chains increase in length. These are ascribed to changes in primary carbon attached to the nitrogen as a function shearing and the rigidity of the molecule. These results reveal interactions taking place at the solid-liquid interface and have impacts on a broad spectrum of industrial, commercial, and research applications including lubrication and transportation vehicles.

Investigations were carried out to study the effect of alternate wetting and drying cycles on the mineralization, nitrification, and denitrification of soil nitrogen in two soils, in the presence or absence of added ammonium and nitrite. Soils were analyzed at the end of each drying cycle for total inorganic nitrogen, ammonium, and nitrite nitrogen. Gaseous products, i.e., ammonia, and the oxides of nitrogen (NO and NO2) were collected in the course of drying for determination. The drying cycles accelerated the rate of nitrogen mineralization in both soils and further increased the oxidation of applied and available ammonium. The rate of ammonium transformation was faster in Yolo clay loam soil than in Miami silt loam. A faster rate of nitrification was also observed in Yolo clay loam. This may be because of a higher pH of the Yolo clay loam soil. The successive drying cycles had a pronounced effect on the nitrate formation in both soils. The extent of nitrite decomposition was inversely related to soil pH. The amount of nitrogen oxides (NO and NO2) evolved were inversely related to soil pH, but significant amounts of NO and N02 were evolved from even the slightly alkaline Yolo clay loam. The loss of nitrogen oxides increased with increased number of drying cycles and, further, the losses of nitrogen increased with increase in nitrite level. The majority of the nitrogen losses from these soils may be due to the direct decomposition of nitrite and possibly slight losses due to an interaction of nitrite and ammonium ions during the course of drying the soil. A considerable amount of nitrogen remained as undetected in treatments receiving either ammonium or nitrite or both. These losses of nitrogen apparently are other than by the release of NO, NO2, and NH3. The undetected nitrogen loss from the soil system may be either in the form of N2O or N2. No volatile losses of ammonia were recorded from the acid Miami silt loam soil. The greatest amount of applied ammonium nitrogen volatilized as ammonia in Yolo clay loam during the initial drying cycles. The rate of ammonia volatilization increased with increase in applied ammonium concentration.

Thesis (Ph. D.)--University of Wyoming, 2006. / Title from PDF title page (viewed on Dec. 21, 2007). Includes bibliographical references (p. 199-216).

Purpose: The relationship between severity of voiding dysfunction and quality of life in children with daytime wetting was analyzed. Materials and Methods: The relationship between age, gender, severity of voiding dysfunction (measured by DVSS) and quality of life (measured by PinQ) in the child with daytime wetting was analyzed. Twenty-four children (4 males, 20 females) aged 5-10 years (x 8.17 years, SD 1.37) and their parents completed the DVSS and PinQ. Results: Parent and child total DVSS and total PinQ Scores had similar results with only a significant mean difference between the parent total DVSS scores based on gender. Only Gender with Parental Total DVSS Score (r = 0.462, p = 0.023) and Child Total DVSS Score with Parent Total DVSS Scores (r = 0.472, p = 0.020) were significant correlations. Conclusions: Results illustrate the importance of early recognition and intervention to minimize the impact daytime wetting has on the child.

The carrier capture and relaxation of Type II ZnTe/ZnSe quantum dots(QDs) were investigated with ultrafast photoluminescence upconversion. We found that carrier relaxation of QDs under Volmer-Weber(VW) growth mode exhibits faster decay and rise than that of QDs under Stranski-Krastanow(SK) growth mode due to the wetting layer in SK growth mode provides as a pathway for carriers to diffuse and migrate from large(small) to small (larger) QDs. The wetting layer level was found by analyze the decay time of PL with different wavelength and temperature. The PL of VW mode and SK mode by using 532nm Nd-YAG laser also prove the existence of wetting layer. We interpret our results of VW mode in terms of Auger process with large carrier density.