Barreiras impermeáveis são uma necessidade em várias obras de engenharia e, em geral, naquelas destinadas à disposição de resíduos, como os aterros e as lagoas de efluentes. Solos compactados têm sido largamente utilizados para essa finalidade. Nesse sentido, esses solos devem ter características apropriadas, como baixa permeabilidade, as quais devem permanecer frente às solicitações de obra. Este trabalho trata do estudo da potencialidade do uso de solos lateríticos compactados em barreiras impermeáveis para sistemas de contenção de resíduos. Neste estudo avaliaram-se os efeitos da umidade e da energia de compactação em duas propriedades importantes para a finalidade desejada, a permeabilidade e a contração, por meio de corpos de prova de dimensões reduzidas, tal qual utilizado na metodologia MCT. Verificou-se que, em geral, a condutividade hidráulica diminuiu com o aumento da umidade, até a umidade ótima, permanecendo praticamente constante ou diminuindo ligeiramente a partir daí. O aumento da energia de compactação diminuiu as condutividades hidráulicas de forma pronunciada no ramo seco da curva de compactação, mas após a umidade ótima as variações foram pequenas para energias acima de 12 golpes. As mínimas condutividades hidráulicas obtidas foram da ordem de '10 POT.-7' cm/s para vários solos ensaiados. Outro fator que também influenciou na diminuição da condutividade hidráulica dos solos foi o aumento da porcentagem de argila. No que se refere às contrações dos solos, o aumento da umidade acarretou em aumento das contrações axiais, que atingiram valores máximos da ordem de 4%. Os solos mais arenosos apresentaram as menores contrações axiais, não ultrapassando valores da ordem de 1%, enquanto para os solos argilosos as contrações médias foram da ordem de 2%. O aumento da energia de compactação acarretou ligeiro aumento das contrações axiais / Impermeable barriers are a need in several engineering works, specially in waste containment systems and effluents ponds. Compacted soils have been used for that purpose. In that sense, the candidate soils should have appropriate characteristics, such as low permeability, which must remain throughout the design life. This work deals with the potentiality of using lateritic compacted soils in impermeable barriers for waste containment systems. In this study the influence of the water content and the compacting energy on the permeability and on the shrinkage of those soils was studied, through specimens of reduced dimensions, as used in the MCT methodology. It was verified that, in general, the hydraulic conductivity decreased with the increase of the water content, until the optimum water content, staying practically constant since then. The increase of the compacting energy reduced the hydraulic conductivities in the dry side of the compacting curve, but beyond the optimum water content the variations were small for energies larger than 12 blows. The lower hydraulic conductivities obtained were of the order of '10 POT.-7' cm/s for several soils. Hydraulic conductivity was also reduced with the increase of the clay percentage. Regarding soil shrinkage the increase of the water content caused an increase on the axial shrinkage that reached maximum values in the order of 4%. The sandy soils presented the smallest axial shrinkage (lower than 1%), while for the clayey soils the average shrinkage reached about 2%. The increase of the compacting effort caused a little increase of the axial shrinkage

A utilização de solo natural misturado com bentonita empregado em camadas impermeáveis para retenção de contaminante é bastante comum em aterros sanitários. Neste trabalho, serão apresentados os resultados de ensaios com misturas de solo-bentonita nos teores de 3%, 5% e 7%, utilizando-se um solo arenoso proveniente da região de Pindorama (SP). Os ensaios de condutividade hidráulica para o solo-bentonita foram realizados em permeâmetros de parede flexível. Os resultados obtidos indicam que para os teores de 5% e 7% de bentonita a condutividade hidráulica apresenta-se com valores adequados para a construção de barreiras impermeáveis. A resistência ao cisalhamento do solo compactado puro e das misturas compactadas foi avaliada através de ensaios triaxiais do tipo consolidado não drenado (CU) e ensaios de compressão simples. A coesão efetiva e o ângulo de atrito efetivo do solo aumentou e diminuiu, respectivamente, com a adição de bentonita. Os ensaios de resistência à compressão simples para as misturas com 5% de bentonita atingiram valores aceitáveis para o emprego em camadas impermeabilizantes. / It is becoming very common the use of soil-bentonite mixtures for building sanitary landfill liners with the purpose of retaining pollutants. This work shows the results of hydraulic conductivity and shear strength tests performed with soil-bentonite mixtures with 3%, 5% and 7% bentonite content. The natural soil was gathered in the Pindorama area, which is located in the northeast of Sao Paulo state. The hydraulic conductivity tests were performed in a flexible wall permeameter. Test results show that mixtures with 5% and 7% bentonite content are suitable, in terms of hydraulic conductivity, for construction of sanitary landfill liners. The shear strength parameters of natural soil and mixtures have been assessed performing undrained triaxial compression tests and unconfined compression tests. The effective cohesion and the effective friction angle increased and decreased with the increase of the bentonite content, respectively. The unconfined compression test results have shown that mixtures with 5% bentonite content are suitable, in terms of shear strength, for construction of sanitary landfill liners.

It is surprising to know the small amount of work that has been done on alternate freezing and thawing of seeds. Many experiments, however, have been conducted to see the effect of very low temperatures on seeds and to notice the effect it had on their vitality. Some experimenters subjected seeds to temperatures as low as liquid hydrogen with very interesting results but in very few cases, if any, was the effect of alternate freezing and thawing studied. The work that follows deals directly with the effects of alternate freezing and thawing on impermeable seeds of alfalfa and of dodder. It is known that this seed does not germinate readily; therefore it often lays over winter in the soil. Does this natural freezing and thawing aid or hinder this impermeable seed in it's later germination? this has been the main question kept in mind throughout this experiment.

Barreiras impermeáveis são uma necessidade em várias obras de engenharia e, em geral, naquelas destinadas à disposição de resíduos, como os aterros e as lagoas de efluentes. Solos compactados têm sido largamente utilizados para essa finalidade. Nesse sentido, esses solos devem ter características apropriadas, como baixa permeabilidade, as quais devem permanecer frente às solicitações de obra. Este trabalho trata do estudo da potencialidade do uso de solos lateríticos compactados em barreiras impermeáveis para sistemas de contenção de resíduos. Neste estudo avaliaram-se os efeitos da umidade e da energia de compactação em duas propriedades importantes para a finalidade desejada, a permeabilidade e a contração, por meio de corpos de prova de dimensões reduzidas, tal qual utilizado na metodologia MCT. Verificou-se que, em geral, a condutividade hidráulica diminuiu com o aumento da umidade, até a umidade ótima, permanecendo praticamente constante ou diminuindo ligeiramente a partir daí. O aumento da energia de compactação diminuiu as condutividades hidráulicas de forma pronunciada no ramo seco da curva de compactação, mas após a umidade ótima as variações foram pequenas para energias acima de 12 golpes. As mínimas condutividades hidráulicas obtidas foram da ordem de '10 POT.-7' cm/s para vários solos ensaiados. Outro fator que também influenciou na diminuição da condutividade hidráulica dos solos foi o aumento da porcentagem de argila. No que se refere às contrações dos solos, o aumento da umidade acarretou em aumento das contrações axiais, que atingiram valores máximos da ordem de 4%. Os solos mais arenosos apresentaram as menores contrações axiais, não ultrapassando valores da ordem de 1%, enquanto para os solos argilosos as contrações médias foram da ordem de 2%. O aumento da energia de compactação acarretou ligeiro aumento das contrações axiais / Impermeable barriers are a need in several engineering works, specially in waste containment systems and effluents ponds. Compacted soils have been used for that purpose. In that sense, the candidate soils should have appropriate characteristics, such as low permeability, which must remain throughout the design life. This work deals with the potentiality of using lateritic compacted soils in impermeable barriers for waste containment systems. In this study the influence of the water content and the compacting energy on the permeability and on the shrinkage of those soils was studied, through specimens of reduced dimensions, as used in the MCT methodology. It was verified that, in general, the hydraulic conductivity decreased with the increase of the water content, until the optimum water content, staying practically constant since then. The increase of the compacting energy reduced the hydraulic conductivities in the dry side of the compacting curve, but beyond the optimum water content the variations were small for energies larger than 12 blows. The lower hydraulic conductivities obtained were of the order of '10 POT.-7' cm/s for several soils. Hydraulic conductivity was also reduced with the increase of the clay percentage. Regarding soil shrinkage the increase of the water content caused an increase on the axial shrinkage that reached maximum values in the order of 4%. The sandy soils presented the smallest axial shrinkage (lower than 1%), while for the clayey soils the average shrinkage reached about 2%. The increase of the compacting effort caused a little increase of the axial shrinkage

A utilização de solo natural misturado com bentonita empregado em camadas impermeáveis para retenção de contaminante é bastante comum em aterros sanitários. Neste trabalho, serão apresentados os resultados de ensaios com misturas de solo-bentonita nos teores de 3%, 5% e 7%, utilizando-se um solo arenoso proveniente da região de Pindorama (SP). Os ensaios de condutividade hidráulica para o solo-bentonita foram realizados em permeâmetros de parede flexível. Os resultados obtidos indicam que para os teores de 5% e 7% de bentonita a condutividade hidráulica apresenta-se com valores adequados para a construção de barreiras impermeáveis. A resistência ao cisalhamento do solo compactado puro e das misturas compactadas foi avaliada através de ensaios triaxiais do tipo consolidado não drenado (CU) e ensaios de compressão simples. A coesão efetiva e o ângulo de atrito efetivo do solo aumentou e diminuiu, respectivamente, com a adição de bentonita. Os ensaios de resistência à compressão simples para as misturas com 5% de bentonita atingiram valores aceitáveis para o emprego em camadas impermeabilizantes. / It is becoming very common the use of soil-bentonite mixtures for building sanitary landfill liners with the purpose of retaining pollutants. This work shows the results of hydraulic conductivity and shear strength tests performed with soil-bentonite mixtures with 3%, 5% and 7% bentonite content. The natural soil was gathered in the Pindorama area, which is located in the northeast of Sao Paulo state. The hydraulic conductivity tests were performed in a flexible wall permeameter. Test results show that mixtures with 5% and 7% bentonite content are suitable, in terms of hydraulic conductivity, for construction of sanitary landfill liners. The shear strength parameters of natural soil and mixtures have been assessed performing undrained triaxial compression tests and unconfined compression tests. The effective cohesion and the effective friction angle increased and decreased with the increase of the bentonite content, respectively. The unconfined compression test results have shown that mixtures with 5% bentonite content are suitable, in terms of shear strength, for construction of sanitary landfill liners.

Monolayer molybdenum disulfide (MoS2) is a three-atom-thick direct band gap semiconductor, which has received considerable attention for use as a channel material in atomically thin transistors, photodetectors, excitonic LED’s, and many other potential applications. It is also a mechanically exceptional material with a large stiffness and flexibility, and can withstand very large strains (11%) before rupture. In this dissertation we investigated the mechanics of the stiffness and adhesion forces in atomically thin MoS2 membranes, and how biaxial strains can be used to induce large modulations in the band structure of the material. First, we used chemical vapor deposition (CVD) to grow MoS2 crystals that are highly impermeable to gas, and used a pressure difference across suspended membranes to induce large biaxial strains. We demonstrated the continuous and reversible tuning of the optical band gap of suspended monolayer membranes by as much as 500 meV, and induced strains of as much as 5.6% before rupture. We observed the effect of strain on the energy and intensity of the peaks in the photoluminescence (PL) and Raman spectra and found their linear strain tuning rates, then report evidence for the strain tuning of higher level optical transitions. Second, we determined the Young’s modulus and works of separation and adhesion of MoS2 membranes, and found that adhesion hysteresis is an important effect in determining the behavior of our systems. Finally, we investigated the use of atomically thin materials as nanofiltration membranes, by perforating the material with nanopores which selectively permit the transport of smaller molecules while rejecting larger ones. We studied ion transport through nanopores in graphene membranes and demonstrate that in-situ atomic force microscope measurements in liquid are a powerful way to reveal occlusions and contaminants around the pores - work which will aid future researchers in further unveiling the properties of these fascinating systems.

Hautphysiologische Untersuchungen zu repetitiven Handschuhokklusionen EINLEITUNG: Berufsbedingte Hauterkrankungen nehmen in Deutschland die führende Position unter den gemeldeten berufsbedingten Krankheiten ein (DGUV 2009). Als ein Risikofaktor für chronische, irritative Kontaktdermatitiden werden repetitive Handschuhokklusionen mit hautphysiologischen Auswirkungen auf die Epidermale Barriere (z.B. Exsikkationseffekte, Barriereschädigungen und Verschiebungen des Hautoberflächen-pH-Wertes) angeführt (FLUHR et al. 2005; FROSCH/JOHN 2006; GRAVES et al. 1995; JUNGBAUER et al. 2004a, 2004b und 2004c; RAMSING/AGNER 1996b; TSAI/MAIBACH 1999; WULFHORST et al. 2010; ZHAI/MAIBACH 2002). In der einschlägigen Literatur wird der hautschädigende Einfluss von Langzeit-Okklusionen jedoch kritisch diskutiert, da widersprüchliche Studienergebnisse vorliegen (FLUHR et al. 1999b; RAMSING/AGNER 1996a und 1996b; WETZKY et al. 2009a). Hardening-Effekte werden als ein Erklärungs-ansatz für die Kompensation hautschädigender Okklusionseffekte angegeben, die auch im Kontext von Spontanremissionen irritativer Dermatitiden trotz konstanter äußerer Risikofaktoren diskutiert werden (ELIAS et al. 2001; LAMMINTAUSTA/MAIBACH 1990; WATKINS/MAIBACH 2009; WULFHORST 1996a, 1996b, 1996c und 2000). ZIELE: Aus diesen Gründen wurden in der vorliegenden Arbeit neben den Kurzzeit- auch die Langzeit-Okkusionseffekte von 14 verschiedenen, impermeablen (Einmal- und Mehrweg-) Handschuh-Testpatches aus den Materialien Polyvinylchlorid, Naturlatex, Nitril und Polyethylen untersucht. Des Weiteren wurde erstmalig versucht, Hardening-Effekte nach repetitiven Handschuhokklusionen hautphysiologisch zu detektieren. METHODIK: An den volaren Unterarmen 40 hautgesunder Probanden wurden mittels der Laborparameter Relative Hornschichtfeuchte (RHF), Transepidermaler Wasserverlust (TEWL) bzw. Skin Surface Water Loss (SSWL), Hautoberflächen-Farbe und Hautoberflächen-pH-Wert hautphysiologische Einflüsse untersucht. Nicht nur die Kurzzeiteffekte wurden 30 Minuten nach singulärer, 4stündiger Handschuhokklusion, sondern auch die Langzeiteffekte einen Tag nach 14maligem, täglich 4stündigem Aufkleben von Handschuh-Patches ermittelt. Unter der Voraussetzung signifikanter Kurzzeit-Okklusionseffekte wurden außerdem potenzielle Hardening-Effekte auf die vier hautphysiologischen Parameter 30 Minuten nach einwöchigen sowie zweiwöchigen, täglich 4stündigen Okklusionen erfasst. Die statistische Auswertung erfolgte anhand nicht-parametrischer Testverfahren (Längsschnitt-Studien: Friedman- und Wilcoxon-Test; Querschnitt-Studien: Kruskal-Wallis- und Mann-Whitney-U-Test). ERGEBNISSE: Während Kurzzeit-Okklusionseffekte auf die Parameter RHF sowie TEWL bzw. SSWL in Form einer signifikanten Hyperhydratation des Stratum corneum (p<.013) bei der Hälfte der untersuchten Handschuhe sowie eine Verschiebung des Hautoberflächen-pH-Wertes in Richtung des alkalischen Bereichs (p=.007) bei einem von 14 Handschuh-Ausschnitten objektiviert werden konnten, wurden keine signifikanten Veränderungen der Hautoberflächen-Farbe 30 Minuten nach einmaliger, 4stündiger Okklusion ermittelt. Des Weiteren ließen sich keine signifikanten Langzeit-Okklusionseffekte – auf keinen der vier Parameter – nachweisen, d.h. keines der 14 untersuchten Handschuh-Testmaterialien bewirkte einen Tag nach täglich 4stündigen Okklusionen über zwei Wochen signifikante Exsikkationseffekte, Barriereschädigungen, Verschiebungen des Hautoberflächen-pH-Wertes in Richtung des alkalischen Bereichs oder Erytheme bzw. Blanching-Effekte. Hinsichtlich des Induktionsversuchs von Hardening-Effekten auf die vier untersuchten hautphysiologischen Parameter ist zu konstatieren, dass keine eindeutigen statistisch belegbaren Hardening-Effekte induziert wurden. Es lagen für einzelne Handschuh-Testpatches jedoch Hinweise vor. DISKUSSION: Da in der vorliegenden Arbeit bei keinem der 14 untersuchten Handschuhe ein hautschädigender Langzeit-Okklusionseffekt detektiert wurde, sind die Gleichsetzung von Feuchtarbeit mit repetitiven Okklusionen anhand impermeabler Handschuhe in der Gefahrstoffverordnung (Fassung von 2007) sowie die Festsetzungen in der Verordnung zur arbeitsmedizinischen Vorsorge (2008) zu diskutieren. Da aufgrund relativ weniger signifikanter Kurzzeit-Okklusionseffekte nur einzelne Handschuhe in die Untersuchung der Hardening-Effekte eingeschlossen werden konnten, ist die dringende Notwendigkeit weiterer Okklusionsstudien gegeben. Dennoch konnten Vorschläge für weiterführende Hardening-Okklusionsstudien abgeleitet werden. Weitere Studien hierzu sind dringend erforderlich, um Vorhersagen treffen zu können, welcher Personenkreis möglicherweise an einer chronischen Form einer irritativen Kontaktdermatitis erkranken und wessen irritative Kontaktdermatitis durch Hardening-Effekte wieder ausheilen könnte. Somit könnte ein wichtiger Beitrag zur Berufsberatung und Berufsprognose geleistet werden (LAMMINTAUSTA/MAIBACH 1990; WATKINS/MAIBACH 2009; WULFHORST 1996a, 1996b, 1996c und 2000).

Methyl bromide (MBr) was widely used as a soil fumigant to manage soilborne pests in plasticulture vegetable production; however, it has been banned by the United Nations Environment Programme. Alternatives to MBr must be implemented to sustain fresh market tomato productivity. Possible MBr alternatives include new fumigant compounds, improved plastic mulch, and grafting. Methyl iodide (MeI) and dimethyl disulfide (DMDS) were tested as fumigant alternatives to MBr for the control of yellow nutsedge and soilborne pathogens of tomato. Virtually impermeable film (VIF) and totally impermeable film (TIF) were tested for fumigant retention and yellow nutsedge control in tomato. Grafting onto resistant rootstocks was tested for bacterial wilt and nematode management in tomato. In the absence of a soil fumigant, TIF suppressed yellow nutsedge better than VIF. TIF increased fumigant retention compared to VIF at similar application rates. Reduced fumigant application rates could be used in combination with TIF while maintaining fumigant concentrations, weed control, and crop yields comparable to greater use rates with VIF. Shank applied DMDS rates could be lowered to 281 L/ha under TIF from 468 L/ha under VIF; shank applied MeI application rates could be reduced to 56 L/ha under TIF compared to 93 L/ha under VIF and drip applied DMDS could be reduced from 561 L/ha under VIF film to 374 L/ha under TIF. Grafting susceptible commercial tomato cultivars onto resistant tomato hybrid rootstocks increased yields and plant survival in bacterial wilt infested fields. "Cheong Gang", "BHN 998", and "BHN 1054" were the best performing rootstocks for bacterial wilt resistance and tomato fruit yield in severely infested fields. Grafting increased tomato yield and decreased root galling from root-knot nematodes in an infested field. Hybrid rootstock "RST 106" resulted in the lowest root-knot nematode galling. In conclusion, TIF with reduced rates of DMDS or MeI is a viable MBr alternative for fresh market tomato production to retain effective doses of fumigant, manage yellow nutsedge and maintain yields. Grafting is an effective MBr alternative to manage bacterial wilt and root-knot nematode and maintain tomato yields. / Ph. D.

[pt] O processo de manufatura de fitas adesivas geralmente envolve uma etapa de retirada dos solventes presentes na solução revestida e formação de uma camada de material semi- sólido sobre um substrato impermeável. Devido a alta espessura de adesivo requerida no produto final e a alta concentração de solventes característica da solução revestida, a secagem se torna, muitas vezes, o gargalo do processo produtivo. Ganhos de produtividade em linhas que podem produzir centenas de milhares de metros quadrados de fita adesiva por mês são importantes para viabilizar incrementos na oferta ou redução dos custos operacionais. Esta dissertação apresenta a análise do processo de secagem de soluções poliméricas revestidas sobre substratos impermeáveis através do desenvolvimento de um modelo matemático para representar os fenômenos de transferência de calor e massa. Também propõe uma metodologia para atingir ganhos de produtividade utilizando um programa computacional especialmente desenvolvido para simulação do processo de secagem. A utilidade da metodologia e da simulação é demostrada por um estudo de caso realizado na manufatura de fitas adesivas da 3M do Brasil. / [en] In the manufacturing process of adhesive tapes usually there is a step where the solvents of solution are evaporated in order to allow the formation of a semisolid layer of material over a suitable substrate. As the final product requires high coating weight and solvent concentration on adhesive solution is high as well, the drying becomes, most of the time, the constraint of the overall process. Productivity increase on machines that can produce hundred of thousands of square meters of adhesive tapes per month can represent additional sale volumes or possibility to reduce operating costs. This dissertation presents the analysis of drying process of polymeric solutions coated over impermeable substrates through the development of a mathematical model to represent the heat and mass transfer. It also proposes a methodology to achieve productivity increases using a computer code specially developed to simulate the drying process. The power of this methodology and of the computer- aided simulation is showed by a case study in the manufacturing department of adhesive tapes at 3M Brazil.

This theses is focused on the description of subsurface in the area of interest - Kopaninský and Jenínský stream catchment - and consequently thy most accurate interpretation depth of impermeable bedrock. Geophysical multicable metod (ERT - electrical resistivity tomography") was selected for field measurements. This method of geophysical survey provides the information on subsurface structures, verifies hypotheses and brings new information on the lithological and structural conditions below the surface. ERT measurements were performed automatically by geoelektrical ARES device in combination with inteligent electrodes. The data obtained by field measurements were plotter in the form of resistive sections (using ReS2DInv software) which were used for the later interpretation. The given results determine the depth and process of impermeable bedrock which are important for more accurate data inputs like for modeling rainfall-runoff processes especially in the field of calibration and validation of each adjustment of models as well as for the next other hydrogical analyzes and studies carried out in the research projects. The purpose of this work is to determine the depth of impermeable bedrock and could serve as a data input for MIKE SHE hydrological modeling.