Aiming to understand the mechanism of ripening of the Fuyu persimmon and extend the storage period, experiments were preformed to evaluate the effect of the period of exposure to low temperature, controlled atmosphere and inhibitor the ethylene action in the beginning or in the end of storage period on the incidence of softening. In the first experiment following treatments were evaluated: [1] 3 days at -0.5°C; [2] 6 days at -0.5°C; [3] 9 days at -0.5°C; [4] 6 days at 10°C; [5] 9 days at 10°C; [6] 15 days at 10°C; [7] 9 days at 15°C and [8] 15 days at 15°C. In the second experiment treatments were obtained by combining the temperature (-0.5; 10; 12.5; 15 e 17.5°C) with and without application of 1-methylcyclopropene (1-MCP), before storage. The laboratory tests were performed after 1 and 2 months storage. In the third experiment at -0.5ºC were evaluated the treatments: [1] cold storage(CS), [2] application of 1ppm of 1-MCP and subsequent CS, [3] CS and subsequent application of 1-MCP, [4] controlled atmosphere (CA) with 1.0kPa O2 + 8.0kPa CO2, [5] application of 1-MCP and subsequent storage in CA, [6] CA storage and subsequent application of 1-MCP. The laboratory tests were performed after 2 months in fruits storage in CS and after 4 months in fruits storage in CA. According to the results of the experiments the period of 9 days at -0.5ºC does not provide sufficient cooling to stimulate the maturation process of persimmon, do not altering the production of ethylene, respiration and softening of the fruit when compared with 15ºC. The storage of Fuyu persimmon for one month at -0.5ºC is sufficient to stimulate the maturation process, with 100% fruit softened after 6 days at 20°C. Already, storage for two months at -0.5°C accelerates the maturation process and leaving 100% fruit soft after 4 days at 20°C. At the temperatures of 10, 12.5 and 15°C occurred softening of fruit during storage, showing that these temperatures for long periods, are also efficient in the unlock process of maturation. The softening is related with the ethylene action and probably with its receptor. The application of 1-MCP before or after storage block the maturation process even in fruit exposed at -0.5°C, not occurring softening after exposure at 20°C. Controlled atmosphere delayed the softening. CA condition with 1.0kPa O2 + 8.0kPa CO2 with application of 1-MCP was the most efficient treatment to control the maturation, but occurred high incidence of decay after 4 months storage of Fuyu persimmon. / Objetivando compreender o processo de amadurecimento do caqui Fuyu e prolongar o armazenamento foram conduzidos experimentos para avaliar o efeito do período de exposição à baixa temperatura, atmosfera controlada e aplicação de inibidor da ação do etileno em dois momentos, no início e no final do armazenamento, sobre o amolecimento, analisados visualmente. No primeiro experimento avaliou-se: [1] 3 dias na temperatura de -0,5°C; [2] 6 dias na temperatura de -0,5°C; [3] 9 dias na temperatura de -0,5°C; [4] 6 dias na temperatura de 10°C; [5] 9 dias na temperatura de 10°C; [6] 15 dias na temperatura de 10°C; [7] 9 dias na temperatura de 15°C e [8] 15 dias na temperatura de 15°C. No segundo experimento, os tratamentos foram originados da combinação de temperaturas (-0,5; 10; 12,5; 15 e 17,5°C) com e sem aplicação de 1-metilciclopropeno (1-MCP), antes do armazenamento. As análises laboratoriais foram realizadas após 1 e 2 meses de armazenamento. No terceiro experimento, na temperatura de -0,5ºC foram avaliados os seguintes tratamentos: [1] AR; [2] aplicação de 1ppm de 1-MCP durante 24h e posterior AR; [3] AR e posterior aplicação de 1ppm de 1-MCP durante 24h; [4] atmosfera controlada (AC) com 1,0kPa de O2 + 8,0kPa de CO2; [5] aplicação de 1ppm de 1-MCP 24h e posterior armazenamento em AC; [6] armazenamento em AC e posterior aplicação de 1ppm de 1-MCP. As análises laboratoriais foram realizadas após 2 meses nos frutos armazenados em AR e após 4 meses nos frutos armazenamentos em AC. Segundo os resultados dos experimentos, o período de 9 dias na temperatura de -0,5ºC não fornece frio suficiente para estimular o processo de maturação do caqui, não alterando a produção de etileno, a respiração e o amolecimento dos frutos em relação a 15ºC. O armazenamento de caqui por um mês na temperatura de -0,5ºC é suficiente para estimular o processo de maturação, com 100% dos frutos amolecidos aos 6 dias de exposição a 20ºC. Já, o armazenamento por dois meses na temperatura de -0,5ºC torna 100% dos frutos amolecidos aos 4 dias de exposição a 20ºC. As temperaturas de 10; 12,5 e 15ºC ocasionam amolecimento dos frutos durante o armazenamento, o que indica que essas temperaturas por longo período de tempo também são eficientes no desbloqueio da maturação. O amolecimento tem relação com a ação do etileno e, mais provavelmente, com o seu receptor. A aplicação de 1-MCP, antes ou após o armazenamento, bloqueia o processo de maturação, mesmo em frutos expostos ao frio de -0,5°C, evitando o amolecimento do caqui após exposição a 20ºC. A atmosfera controlada retardou o amolecimento, sendo que a condição de AC de 1,0kPa de O2 + 8,0Pa de CO2 com aplicação de 1-MCP foi a condição mais eficiente no controle da maturação, mas ocorreu alta incidência de podridão após 4 meses de armazenamento.

Underground excavations break the balance of the initial stress field and cause stress redistributions in the surrounding rock masses. Problems normally arise as the stress exceeds the rock mass strength. In addition, the rock mass contains preexisting defects, such as the fissures, fractures, joints, faults, shear zones, dikes, etc., which could significantly weaken the rock mass strength and make the rock mass behavior complicated. The stability of underground excavations is of great importance to an operating mine project since it ensures the safety of the working environment and the successful ore exploration. Due to the complex geological conditions and engineering disturbances, the assessment of rock mass stability for a practical engineering problem is extremely challenging and difficult, which needs to be solved by the modern numerical methods. In this dissertation, the rock mass stability around tunnels in an underground mine in the USA was investigated by performing three-dimensional modeling using the 3DEC 3-Dimensional Distinct Element Code. Comprehensive stress analyses were respectively carried out on a preliminary model and a more advanced model. In the preliminary study, the built model contains the inclined lithologies, a non-persistent fault, and a convoluted tunnel system. The geomechanical property values used for the rock masses and discontinuities in the numerical model were estimated using the available geotechnical information and the experience of the research group. The Mohr-Coulomb and strain softening constitutive relations were prescribed for the rock masses; the coulomb slip joint model was assigned for the discontinuities. The influence of the boundary conditions, block constitutive models, horizontal in situ stress and rock support system on the tunnel stability was investigated. The rock mass behavior was quantified using the results of stress, displacement, and yielded zones around the tunnels. It showed that the roller boundary conditions resulted in slightly different but comparable results with the combined boundary conditions (roller and stress combined) where K0 equals to 0.4 or 0.5. Whereas the in-situ stress field for a complex geological system can only be obtained by applying proper boundary stresses and then by performing stress analysis. The softening behavior of the rock masses caused more deformations and yielded zones around the tunnels; the rock masses around the tunnels were observed to reach the residual strength values, which can be treated as failed areas. In addition, the M-C and s-s rock masses reacted differently as the K0 value changed. At K0=1.0, the tunnels seemed to be the most stable; K0=1.5, however, provided the worst scenario with roof and floor problems. With respect to the effectiveness of the support system, a large amount of the bonds of the supports was failing, thus, the deformations and yielded zones around the tunnels were slightly improved. Finally, comparisons between the numerical modeling results and the field measurements implied the applicability of strain softening behavior and a K0 value between 0.5 and 1.0 for the mine. Based on the specific geological, geotechnical, and construction information, a numerical model incorporating accurate features was developed. It includes a non-planar, weak interlayer, the persistent and non-persistent faults, and the open and backfilled excavations. The mechanical property values used for the rock masses and faults were estimated based on the laboratory test results of the intact rock and smooth joints. The strain softening behavior was specified for the rock masses belonging to the average quality, and the rock masses that reached residual strengths were assumed to be failing. The linear relations between the fault stiffnesses and normal stress were described using the continuously yielding joint model. To simulate the mine construction process in the field, the sequential excavation, backfilling, and supporting procedures were numerically implemented; additionally, a novel routine was applied to account for the delayed installation of the supports. Results showed that the tunnels close to the fault and the backfilled area were less stable. Most of the displacements around the tunnels occurred within a distance of zero to 2 or 3 m from the tunnel surface. The varying K0 value caused great changes in the rock mass behavior and the shear behavior of the major fault; significant instability of the tunnels was triggered by the high horizontal in situ stress. Parametric studies on the rock mass condition, rock mass residual strengths, and fault property values showed that the tunnel stability was more sensitive to the former two factors than the last one. A systematic investigation was conducted to evaluate the current rock supports installed at the mine where the increasing stress relaxation was incorporated. The deformations and of the failure zone thicknesses around the tunnels were reduced up to 8% and 20% after applying the supports instantaneously, and the reductions were improved by the delayed installation of supports. Additionally, the safety of supports was evaluated by the bond shear and bolt tensile failures, which was also improved with incorporation of delayed supporting. It was found that the current rock supports are insufficient in length, bond and tensile strengths. Therefore, a stronger support system was suggested. The stronger supports worked better in stabilizing the tunnels. Based on the deformations and failures of the rock masses, the length of the bolts on walls was suggested to be 4-5 m. At the end, the horizontal convergence strain predicted by the numerical simulations were calculated at two locations where the tape extensometers were installed. Good agreements with the field measurements were obtained for the cases that have the average rock mass properties and K0 values in the range 0.5-1.25.

No description available.

Capacitive deionization technologies have gained significant attention in recent years. The development and availability of a variety of materials have enabled the growth of research on electrosorption, which makes capacitive deionization increasingly attractive. This technology has a wide range of applications, such as softening, desalination and selective removal, each of which has been the focus of the experimental part of this work. The theoretical part is devoted to the issue of functioning of capacitive deionization, electrode material and especially the specific application. Water desalination is a major issue, given the global shortage of drinking water and the possibility of using capacitive deionization as a competitive method to conventional desalination methods. Conversely, softening and selective removal of ions can pose everyday problems both in the treatment of drinking water or pre-treatment of industrial water and in the treatment of wastewater. In this diploma thesis, it was proved that the method of capacitive deionization can be used to solve all the above problems. Although capacitive deionization is not a commercially available technology in the Czech Republic yet, it can be expected to be used more and more in the future.

Asphalt binder ageing and experiences with various ageing methods from abroad are described in this thesis. The practical part deals with the RTFOT aging and with the influence of the duration of this test. The comparison of test results is conducted before and after the aging by values of needle penetration, elastic recovery, softening point and resilience tests are evaluated and compared.

No description available.

[pt] Bandas de cisalhamento ocorrem quando há a localização de deformações inelásticas provenientes de esforços cisalhantes em regiões estreitas de um material. Estas estruturas podem influenciar diretamente nas propriedades dos materiais, além de afetar sua integridade e contribuir para o início de falhas estruturais. Este trabalho apresenta uma metodologia para a caracterização das bandas de cisalhamento na rocha carbonática Indiana Limestone por meio de modelagens numéricas utilizando o método dos elementos finitos (MEF). Ao modelar o fenômeno de localização de deformações, o MEF apresenta algumas limitações como perda da elipticidade das equações governantes, produzindo problemas de convergência e resultados dependentes da discretização de malha. Algumas alternativas para superar estes inconvenientes são apresentadas e discutidas, com especial enfase dada à técnica de regularização viscosa utilizada nas modelagens numericas de ensaios biaxiais e triaxiais. Estudos parametricos e de sensibilidade foram conduzidos para identificar o impacto das propriedades mecânicas na ocorrencia das bandas de cisalhamento. Os resultados mostraram que as propriedades de resistência, o uso de leis de fluxo não associadas e o amolecimento por deformação são os fatores que mais influenciam na iniciação e desenvolvimento das bandas de cisalhamento. / [en] Shear bands occur when inelastic shear deformation localize in narrow regions of the material. These structures can directly influence the properties of materials, in addition to affecting their integrity and contributing to the initiation of structural failures. This study presents a methodology for the characterization of shear bands in Indiana Limestone carbonate rock through numerical modeling using the finite element method (FEM). As it is known, the numerical modeling of strain localization phenomena using FEM has some drawbacks, such as loss of ellipticity of the governing equations, triggering convergence problems and results dependent on the mesh discretization. Some alternatives to overcome these problems are presented and discussed, giving a special emphasis to the viscous regularization technique used in the numerical modeling of biaxial and triaxial tests. Parametric and sensitivity studies were performed to identify the impact of the mechanical properties on the occurrence of shear bands. The results showed that strength properties, non associative flow rules and strain-softening are the factors with larger influence on the initiation and development of shear bands.

Networks of crosslinked keratin filaments are abundant in epithelial cells and tissues, providing resilience against mechanical forces and ensuring cellular integrity. Although studies of in vitro models of reconstituted keratin networks have revealed important mechanical aspects, the mechanical properties of crosslinked keratin structures remain poorly understood. Here, we exploited the power of electron beam irradiation (EBI) to crosslink in vitro networks of soft epithelial keratins 8 and 18 (k8–k18) filaments with different irradiation doses (30 kGy, 50 kGy, 80 kGy, 100 kGy, and 150 kGy). We combined bulk shear rheology with confocal microscopy to investigate the impact of crosslinking on the mechanical and structural properties of the resultant keratin gels. We found that irradiated keratin gels display higher linear elastic modulus than the unirradiated, entangled networks at all doses tested. However, at the high doses (80 kGy, 100 kGy, and 150 kGy), we observed a remarkable drop in the elastic modulus compared to 50 kGy. Intriguingly, the irradiation drastically changed the behavior for large, nonlinear deformations. While untreated keratin networks displayed a strong strain stiffening, increasing irradiation doses shifted the system to a strain softening behavior. In agreement with the rheological behavior in the linear regime, the confocal microscopy images revealed fully isotropic networks with high percolation in 30 kGy and 50 kGy-treated keratin samples, while irradiation with 100 kGy induced the formation of thick bundles and clusters. Our results demonstrate the impact of permanent crosslinking on k8–k18 mechanics and provide new insights into the potential contribution of intracellular covalent crosslinking to the loss of mechanical resilience in some human keratin diseases. These insights will also provide inspiration for the synthesis of new keratin-based biomaterials.

No description available.

Discrete (mm- to m-scale) mylonitic shear zones in the northeastern Harquahala metamorphic core complex, Arizona, show evidence of fluid-mineral interactions catalyzing deformation and metamorphism. Many contain a deformed central epidote vein with adjacent bleached haloes and flanking paired shear zones that indicate significant fluid-rock interaction during deformation. An integration of structural and geochemical methods was employed to understand timing, metamorphic conditions, and physiochemical processes responsible for producing the discrete shear zones. Field and microstructural evidence suggest the zones initiated on antecedent fractures. Electron backscatter diffraction (EBSD) analyses show a significant coaxial contribution to the shear, and quartz deformation predominately by prism <a> slip, along with some rhomb <a> slip, suggesting amphibolite-facies conditions during shearing. Fourier Transform Infrared spectroscopy analyses of quartz reveal higher water contents within shear zones than within country rocks, indicating fluid infiltration synchronous with shearing. Stable isotope analyses of quartz and feldspar from mylonites are consistent with an igneous or metamorphic fluid origin. Microstructural observations suggest that the zone morphology with epidote veins, bleached haloes, and flanking discrete paired shear zones was developed predominantly from reaction softening mechanisms. The increase in deformation from bleached rock to flanking shear zones is marked by progressive modal increases in biotite and myrmekite, and modal decreases in K-feldspar, and locally epidote and titanite. Myrmekitic textures recrystallized readily and resulted in progressively greater grain size reduction of feldspar, which aided in the progressive alignment and linkage of the biotite grains, which together concentrated the deformation in bands. Volume reduction resulting from some of the metamorphic reactions may have led to a positive feedback cycle among fluid infiltration, metamorphism and deformation. U-Pb isotope analyses of syn-metamorphic titanite yield an age of ~70 Ma, suggesting the shear zones formed during cooling of the Late Cretaceous (75.5±1.3 Ma) Brown’s Canyon pluton, consistent with their top-to-the-southwest sense of shear, rather than during top-to-the-northeast directed Miocene metamorphic core complex exhumation. Petrography, EBSD analyses, and U-Pb dating of titanite from other (non-discrete) mylonites in the area imply most formed synchronously with the discrete shear zone mylonites. Only rare, scattered mylonites show features consistent with metamorphic core complex exhumation. / text