Diss--Sozialwissenschaften--Augsburg, 1980. / Bibliogr. p. 253-270.

The deep mining industry and civil engineering need to perform rock stability analyses during excavation projects. These analyses are closely related with displacements in tunnel contours. The ground reaction curve is a powerful tool to characterize these displacements that is widely used in the New Austrian Tunneling Method. However, the analytical solutions that exist are only applicable under isotropic stress conditions for deep tunnels. This study aims to investigate when it is possible using the analytical methods to determine the ground reaction curves with enough accuracy in the case of shallow tunnels under anisotropic in-situ stress conditions. The method begins with a literature study. After that, with the help of a 2D model, a comparison between the analytical and the numerical solutions for ground reaction curves at different depths and at different initial in-situ stress ratios was carried out. The results show that both crown and floor displacements deviate more from the analytical solution than the wall displacement. The crown and floor can even move upwards under high initial in-situ stress ratios for shallow tunnels. Because of that, the analytical solution of the ground reaction curve at shallow depths under anisotropic stress conditions should not be used. In the case of isotropic stress field conditions for the analysis in this study, the results given by the analytical solution agree with the numerical ones at depths higher than 14 times the radius of the tunnel. On the other hand, the difference between numerical and analytical solutions becomes higher while increasing the initial in-situ stress ratio, even for very deep tunnels. Furthermore, an empirical equation to obtain the displacements of the ground surface, tunnel wall and tunnel crown has been obtained after a multiple linear regression analysis.

Student Number : 9901196J - MSc dissertation - School of Pathology - Faculty of Science / Fragile sites are highly unstable regions of the genome, which have a tendency to form gaps and breaks in metaphase chromosomes under replication stress conditions. There are many common fragile sites in the human genome and exposure to carcinogens may affect several genes localised in fragile sites within a single cell, which could lead to activation of oncogenes and inactivation of tumour-suppressor genes simultaneously. FRA3B on chromosome 3 and FRA16D on chromosome 16 are the two most commonly expressed fragile sites and contain the FHIT and WWOX genes respectively. These genes are tumour suppressor genes and are inactivated in a number of different ways. Carcinogens found in cigarette smoke have been found to increase fragile site expression and could alter the integrity of theses genes in active smokers. Ten healthy non-smoking (control) individuals and twenty active smokers were recruited for the purpose of this study. Fluorescence in situ hybridisation was performed with probes spanning spanning the FHIT gene and RT-PCR was performed to assess both FHIT and WWOX expression. No significant difference in breaks at fragile sites was observed between controls and active smokers in the FISH experiments. In addition, no aberrant transcripts were detected for either FHIT or WWOX with RT-PCR. Although the sampling group was limited and heterogenous, no increase in the expression of breaks at fragile sites was seen in active smokers in the present study.

Super-Dwarf wheat plants were grown in simulation growth chambers under 12 treatments with three photoperiods (18 h, 21 h, 24 h) and four carbon-dioxide levels (360, 1200, 3000, and 7000 11mol/mol). Carbon-dioxide concentrations affected flower initiation rates of Super-Dwarf wheat. The optimum C02level for flower initiation and development was 1200molμ•mol-1. Super-optimum C01 levels delayed flower initiation, but did not decrease final flower bud number per head. Longer photoperiods not only accelerated flower initiation rates, but also decreased deleterious effects of super-optimum C02. Flower bud size and head length at the same developmental stage were larger under longer photoperiods. But final flower bud number was not affected by photoperiod. Stomatal densities on the abaxial surface were more sensitive to the variation of photoperiod and C02 level than those on the adaxial surface for Super-Dwarf wheat. Stomatal density did not significantly change on the adaxial surface, but was significantly decreased on the abaxial surface under longer photoperiods and higher C02 levels at 27 day after planting (DAP). Cell-walls of both stem and leaf tissues did not significantly change with variation of photoperiod and carbon-dioxide levels at either seedling stage or mature stage. McDowell fixative was suitable for long-term storage of plant tissue for use in light microscopy. When stored up to 180 d, there was no significant change in leaf thickness, shape and size of mesophyll cells, and shape of chloroplasts for wheat leaves under the light microscope.

The aim of the study was to obtain and elaborate information focused on metamorphoses of Borrelia burgdorferi sensu lato (s.l.) spirochetes. The research included detection of various stress conditions for production of dormant forms of Borrelia burgdorferi s.l. spirochetes in vitro. Subsequently, metamorphoses from dormant to motile stages was observed under favourable conditions. Proper PCR method for primers aimed to detect dormant forms of Borrelia was delevoped. The infectious potential of dormant spirochetes of Borrelia burgdorferi sensu stricto (s.s.) complex was observed in vivo. Transformations of spirochetes have also been observed in real time and individual stages have been recorded.

Safety is the most important aspect to the mining industry. Research having a direct and positive impact on mine safety is always needed and should be supported. There are several different types of primary roof supports that are used to try to maintain stable mine workings in order to extract the coal safely. The majority of roof bolts installed annually in underground coal mines in the USA use resin cartridges (Tadolini, 2006). The standard roof bolt used is a fully grouted resin rebar bolt. This is considered a passive (un-tensioned) support. Technological advances in roof support anchored with resin grout systems have resulted in the development of supports that are active (tensioned during installation). Generally it is thought that active anchors are superior in performance as roof support except in highly laminated weak roof. The assumption is that since an active system applies some pre-tension to the roof, it will provide a more stable roof beam. There is, however, a lack of real data to back up this perception. A systematic attempt is through this project that addresses this knowledge gap. Without a clear idea on how different roof bolt systems work in-situ, the consequences could have a significant impact on the safety of the miners working underground as well as production costs. Supports are now often only chosen based on perceived ideas instead of real data. Such assumed superior performance of the support system could lead to false economy. Essentially, it needs to be demonstrated to what degree or under what conditions, if any, these technological advances in roof support improve ground conditions and opening stability and ultimately improve the safety of the miners. There is an argument regarding whether passive bolts could truly be better than active bolts. The focus is centralized towards a cost and performance issue. The overall goal of the proposed project was to develop an understanding of the interaction between different roof bolt types and the immediate strata in a longwall headgate as the longwall face progresses. In order to monitor the interactions between the strata and roof bolts, specially instrumented bolts were installed with six strain gauges that were electronically accessed. A look into the initial bolt loads was used to compare three different bolt types (both tensioned and untensioned) upon installation. These loads continued to be monitored and analyzed as the longwall face approached and passed the location of the instrumented bolts. Along with analyzing instrumented bolt data compared to a passing longwall face, a limited finite element model was set up within Flac3D to represent real conditions, and compare the in situ data collected to the computer outputs in order to establish beginning phases of validating the results.

The presented work was focused on the comparison between the production of selected metabolites by carotenogenic yeasts and microalgae cultivated under conditions of external stress. The main metabolites of interest were carotenoids, further lipophilic substances and lipids. Biotechnological overproduction of these metabolites could serve as a source of potentially beneficial substances not only for the pharmaceutical, cosmetic and food industries, but also for the production of third generation biofuels. Recently, there has been a growing interest in biofuels primarily from microalgae, which have a high potential in biofuel production and seem to be a promising source. The theoretical part deals with the description of individual genera of carotenogenic yeasts, microalgae, cyanobacteria, chemical composition of produced metabolites and brief biosynthesis. In addition, individual methods for analyzing the production of the metabolites of interest were described. The experimental part is focused on the comparison of production of carotenoids, coenzyme Q, ergosterols (phytosterols) and lipids by yeasts, microalgae and cyanobacteria. As a source of external stress, temperature, salt and light stress were chosen. The strains of Rhodotorula glutinis, Rhodotorula mucilaginosa, Sporidiobolus pararoseus and Cystofilobasidium macerans were studied from the yeast strains. Microalgae and cyanobacteria were Scenedesmus obliqus, Scenedesmus dimorphus, Chlorella sorokiniana, Chlorella saccharophila, Botryococcus brauni, Synechococcus nidulans and Arthrospira maxima. The yeast and algal strains were optimized for growth, carotenoid and lipid production. Applied salt stress showed a significant liquidation effect on algal and cyanobacterial strains. The thesis also monitored the biological stress, so-called co-cultivation of microalgae and yeasts. Further experiments will be the subject of future work.

The aim of this diploma thesis is to optimize a method of interfacial rheology for testing the interfacial behaviour of biofilms on the liquid-air interface and after that use the method for studying the biofilm formation under optimal and stress conditions. For studying the biofilm formation, Kombucha was used. It is a microbial culture forming a cellulose biofilm on the interface. As the stress conditions, reduction of sucrose concentration, change of pH and change of ionic strength was used. Next, the ability of regeneration of biofilm formed on the interface was studied. The biofilm formation was occured in all cases except of increasing ionic strength. As expected, the best biofilm biofilm growth was observed under optimal condition, which means a sucrose concentration 100 g/l.

In a bacterium's environment, life conditions are subject to constant changes. One of the proposed mechanisms of adaptation to these changes is the increase in mutation rate. Bacterial mutability is generally kept very low by action of various mechanisms of control and repair, one of the most important ones being the Mismatch Repair, which is the master regulator of genetic stability of organisms. When its function is impaired, larger amounts of mutations occur in cells. In adverse conditions, these might be beneficial for cells' adaptation. The role of these repair mechanisms in adaptive processes in Bacillus subtilis has not yet been definitely resolved. The previous work in our lab focused on establishing an experimental system to measure the extent of mutagenesis in B. subtilis, and the influence of several stresses on mutation rate was assessed. No significant increase in mutability was found to be triggered by nutrient limitation in stationary growth phase, hyperosmotic stress or increased cultivation temperature. Furthermore, a system to monitor the expression of mismatch repair proteins was constructed, which has not revealed significant differences between stressed and nonstressed growth conditions. This thesis follows the results of previous experiments, expanding the range of stresses...

Conselho Nacional de Desenvolvimento Científico e Tecnológico / This work presents as objective to study the simultaneous influence of pH, temperature and sulphite concentration on situations comprising stress situations for the yeast on the alcoholic fermentation by the use of a central composite design (CCD). The yeast Saccharomyces cerevisiae Y-940 was used and the experiments were carried out in a temperature and agitation controlled mixture reactor with a useful volume of 2L. The conditions defined on the CCD were: temperature ranging from 21.5 to 48.5ºC, pH ranging from 1.5 to 5.5 and sulphite concentration ranging from 0 to 345mg/L. The fermentations were accompanied throughout time by sucrose, ethanol, glycerol and cells concentrations and, by the end of 12 hours, cell viability and trehalose concentration were determined as well. From the obtained data, cell viability, the final amount of intracellular trehalose, ethanol yield and productivity and glycerol yield were analyzed as responses. The variables values that maximized the cell viability were temperature ranging from 21.5 to 31ºC, pH ranging from 3.2 to 4.2 and sulphite concentration from 0 to 45mg/L. For the final amount of trehalose, the temperature interval that maximized the response ranged from 23.5 to 38ºC, the pH ranging from 3.5 to 4.6 and the sulphite concentration ranging from 0 to 90mg/L. To achieve the maximum ethanol yield (g/g), the temperature ranged from 32.5 to 39ºC, the pH ranged from 3.5 to 4.3 and the sulphite concentration from 0 to 90 mg/L. The ethanol maximum productivity (g/L.h) was attained in a temperature of 33.5ºC, in a pH of 3.9 and in absence of sulphite. The conditions for a maximum glycerol yield were: 48.5ºC, pH of 5.5 and a sulphite concentration of 345 mg/L. With the objective of investigating the sulphite effect on fermentation with a greater level of detail, additional experiments were conducted by adopting conditions that allowed to evaluate the isolated effect of sulphite on fermentations, allowing to reach the conclusion that greater sulphite concentrations generates a high glycerol yield and lowers ethanol productivity and cell viability. The fermentation kinetic at the point defined as optimal by analyzing the CCD responses was well adjusted to the model proposed by Ghose and Thiagy. The found μmax parameter was 0,15h-1, Ks of 3,31g/L, Ki of 135,87g/L and a Pm of 84,23g/L. / O presente trabalho teve como objetivo estudar a influência conjunta do pH, temperatura e concentração de sulfito em condições que englobaram situações de estresse para levedura na fermentação alcoólica, utilizando um planejamento composto central (PCC). Foi utilizada a levedura Saccharomyces cerevisiae Y-940, sendo os ensaios conduzidos em um reator de mistura com volume útil de 2L, com controles de temperatura e agitação. As condições definidas pelo PCC foram: temperatura na faixa de 21,5 a 48,5°C; pH de 1,5 a 5,5 e a concentração de sulfito de 0 a 345 mg/L. As fermentações foram acompanhadas ao longo do tempo pelas medidas de concentrações de sacarose, etanol, glicerol e células e, ao final de 12h, foram determinadas, também, a viabilidade celular e a concentração de trealose, sendo analisadas como respostas a viabilidade celular, a quantidade final de trealose intracelular, o rendimento e produtividade de etanol e rendimento em glicerol. As faixas das variáveis que maximizaram a viabilidade celular foi temperatura de 21,5 a 31ºC, de pH de 3,2 a 4,3, e concentração de sulfito de 0 a 45 mg/L. Para a quantidade final de trealose, o intervalo da temperatura que maximizou a resposta foi de 23,5 a 38ºC, o pH, de 3,5 a 4,6 e a concentração de sulfito, de 0 até 90mg/L. Para atingir o máximo rendimento em etanol (g/g) a faixa de temperatura foi de 32,5 a 39°C, o pH de 3,5 a 4,3 e a concentração de sulfito de 0 a 90mg/L. A máxima produtividade de etanol (g/L.h) foi obtida nas condições de temperatura de 33,5ºC, pH de 3,9 e na ausência de sulfito. As condições para o máximo rendimento de glicerol foram: temperatura de 48,5°C, pH 5,5 e concentração de sulfito 345mg/L. Com o objetivo de se investigar mais detalhadamente o efeito do sulfito na fermentação foram realizados experimentos complementares, adotando-se condições que permitiram avaliar o efeito isolado do sulfito na fermentação e concluiu-se que maiores concentrações de sulfito no meio geram maior rendimento em glicerol e menores produtividade de etanol e viabilidade celular. A cinética da fermentação no ponto definido como ótimo pelas análises das repostas do PCC se ajustou bem ao modelo proposto por Ghose e Thiagy. O parâmetro μmax encontrado foi de 0,15h-1, Ks de 3,31g/L, Ki de 135,87g/L e o Pm de 84,23g/L. / Mestre em Engenharia Química