The freeze-thaw process controls several hydrologic processes including infiltration, runoff, and soil erosion. Simulating this process is important particularly in cold and mountainous regions. The Soil and Cold Regions Model (SCRM) was used to simulate, study, and understand the behavior of 12 homogenous soils, subject to a freeze-thaw process based on meteorological data at a snow dominated forest site in Laramie, WY, from 2010 and 2012. To complete a simulation, which accounts for all three phases of water (liquid, vapor, and ice), the model requires meteorological data, canopy characteristics, soil physical properties including the van Genuchten-Mualem parameters, and the initial state of the soil profile. Different model conditions were applied included the relationship between soil pore size, soil particle contact, soil thermal conductivities, soil ice/water content, snow cover, and meteorological data. Analysis of the simulations used metrics such as soil frost depth, days with ice, and maximum ice content. The results showed a threshold in snow depth ranging from 20 to 40 cm to fully insulate the soil from the atmosphere. Additionally, the model showed that the freeze-thaw process was strongest in the period with a shallow snow pack and that particle packing within the soil profile was an important factor in this process. Soil texture and water content controlled soil thermal properties. Water movement towards the freezing front was especially important in fine textured soils, where water and ice was concentrated in the upper layers. In coarser textured soil, frost also occurs, but not to the same extent. Based on these results, future research that combines a broader set of soil conditions with an extended set of field meteorology data could elucidate how soil texture controls thermal properties related to soil frost.

Many different bacteria have essential roles in the process ofrecycling organic waste, making them useful tools when it comes toestablishing artificial ecosystems, a key technology to master inthe expansion of human space travel.In order to further investigate bacteria growth conditions duringspace travel, the MOREBAC experiment was formulated. The objectivewas to design an experimental setup and develop measurementequipment with the capability of confirming successfulresuscitation of freeze-dried bacteria in space by measuringbacteria growth, on-board the student-built MIST-satellite.The experimental setup prototype consisted of an acrylic chipwherein the bacteria would be placed during experiments and anoptical measurements configuration using a photosensor with thepurpose of detecting bacteria cell growth. For experimentalenvironment monitoring, a temperature sensor and a pressure sensorwere calibrated.An Arduino Nano microcontroller was programmed to control allelectrical components during measurements. During the opticaldensity measurements blue dyed water and E.coli bacteria innutrition media were used as test samples.Provided varying blue dye or bacteria cell concentrations, in theform of dilution series and growth-over-time-series, the equipmentproved capable of producing measurements that indicate the opticaldensity of the test sample.Furthermore, a prototype experiment protocol simulating eventsthat will occur in the final experiment design, was implementedand was able to produce real-time monitoring graphs of optical,temperature and pressure measurements, as well as documentation ofall events and measurement data. / MOREBAC / MIST

Enzimas são proteínas utilizadas em processos tecnológicos diversos. Estas enzimas dependendo do tipo e grau de pureza são geralmente caras. Comumente as enzimas exigem controle contínuo do processo no que se refere à temperatura, pH, agitação, entre outros, e após o uso são descartadas, o que torna o custo do processo mais elevado. Em decorrência disto, a imobilização de enzimas em suportes insolúveis e inertes, vem sendo proposta com resultados promissores de manutenção e até mesmo aumento da atividade enzimática, resistência mecânica, térmica e de pH, bem como por apresentar maior facilidade de remoção da enzima do sistema e possibilitar sua reutilização. Por causa disto, diferentes tipos de suportes vêem sendo estudados, dentre estes, os materiais poliméricos, tem recebido atenção especial. A quitosana é um polímero natural, biocompatível, biodegradável e atóxico. É obtida de fontes renováveis provenientes do descarte de cascas de crustáceos da indústria de alimentos, o que constitui um fator ambiental importante atualmente. Neste trabalho a enzima pepsina foi imobilizada em membranas liofilizadas de quitosana e O-carboximetilquitosana reticuladas ou não com glutaraldeído. A pepsina imobilizada na membrana de quitosana reticulada com glutaraldeído manteve sua atividade enzimática e o suporte apresentou propriedades físico-químicas de resistência a solubilização em pH ácido, o qual é necessário para atividade da pepsina. O processo de liofilização preservou a estrutura do suporte e não comprometeu a atividade enzimática. Demonstrando que o processo de liofilização é viável para secagem e incorporação de enzimas. / Enzymes are proteins used in a wide variety of biotechnological processes. Commonly, enzymes require stringent conditions, such as a particular pH, temperature, stirring, etc. In chemical and biochemical reactions, purified enzymes can be rather costly and additionally, must be discarded after each use, which is still less economical. As a result of this, enzyme immobilization on insoluble and inert supports has been studied as a manner to overcome these problems and optimize enzymes use. Promising results of greater immobilized enzyme activity and stability over a broader range of pH and temperature have been reported. As well, immobilized enzymes can be easily removed from the system and reused. Various materials have been employed as enzymes supports, among then, the polymers have received special attention. Chitosan is a natural polymer that presents biocompatibility, biodegradability and nontoxicity. Chitosan is obtained from crustacean shell wastes discarded by the food industry, and recover this material constitutes an important environmental factor nowadays. In this work the enzyme pepsin was immobilized on freezedried chitosan and O-Carboxymethylchitosan membranes crosslinked or not with glutaraldehyde. Pepsin immobilized on chitosan membrane crosslinked with glutaraldehyde maintained its enzymatic activity and the polymer support provided physicochemical properties such resistance to dissolution in acid pH. Acid pH is required for pepsin activity. The freeze-drying process preserved the support structure and did not compromise the enzymatic activity. Demonstrating that, freeze drying process, is viable for drying and enzymes incorporation.

In this Thesis, we propose a mechanism to dynamically adjust the video bit rates through the segmentation and the reassembly of SVC (Scalable Video Coding) segments in a P2P network. At the transmitter, an SVC film is segmented into a number of segments with different sizes. Each segment is further chopped into Torrents according to three scalabilities of SVC (Temporal, Quality, and Spatial). The Torrents with three scalabilities are referred to as 3D-Torrents. At the receiver, we present three approaches of grabbing Torrents (Temporal-First, Quality-First and Interleaving) form P2P networks to validate that the proposed 3D-Torrent reassembly can adapt to different bandwidths and to fit different hardware equipments so that any possible video freeze-up time can be avoided. To demonstrate how the proposed 3D-Torrent reassembly affect video bit rates in the P2P video streaming environment, we implement the segmentation, grabbing, and reassembly of Torrents on a Linux platform. In the P2P network built by Hadoop, we study (i) the video freeze-up time with/without adopting 3D-Torrent reassembly, (ii) video quality under different grabbing approaches using two different types of video, static and active background. To compare the video quality at the transmitter to that at the receiver, we modify the conventional PSNR equation. Two new dimensions, Temporal and Spatial, are included in the new PSNR3D equation to compare the video quality between the transmitter and the receiver. From the experimental results, we observe that the freeze-up time approaches zero using the 3D-Torrent reassembly and video bit rates can be dynamically adjusted according to the available bandwidth.

No description available.

A field experiment was carried out in Ontario, Canada to compare independently measured soil N2O profile concentration and surface N2O flux measurements overwinter and at spring thaw, to estimate the soil N2O content accumulation overwinter, and to estimate the magnitude of the contribution of the physical release of trapped N2O to surface fluxes at spring thaw. Gas samples at various depths were taken and N2O concentrations determined, soil profile gaseous N2O content was calculated by estimating the air-filled pore-space from soil condition measurements, and soil aqueous N2O content was calculated using liquid water content measurements and applying Henry’s Law. Soil N2O content was found to reach a maximum of ~25 mg N2O m-2, and by comparing changes in soil N2O content to surface fluxes measured using the micrometeorological flux-gradient technique, the physical release of previously produced N2O was estimated to contribute up to 47% of spring thaw N2O surface fluxes.

Microbes have a remarkable ability to adapt to a host of environmental stressors, including low temperature, high pressure and osmotic stresses. The adaptations of resistant microbes to low temperatures are varied, and may include the accumulation of solutes to maintain osmotic balance, the production of antifreeze proteins (AFPs) or ice nucleation proteins (INPs) to manipulate ice growth or formation. AFPs depress the freezing point, inhibit ice recrystallization, and have been reported to inhibit or delay the growth of gas hydrates. Conversely, INPs precipitate ice formation at relatively high subzero temperatures. Collectively, these activities can be described as ‘ice-association’ activities. Here, ice-affinity and/or freeze-thaw cycling were used to either select for isolates with ice association properties or to assess the low temperature resistance of microbial consortia derived from various environments. Ice-affinity successfully selected psychrotolerant microbes from cultured temperate and boreal soils, some of which had been previously reported in glaciers and Arctic/Antarctic sites. Many of the recovered microbes demonstrated ice-association activities. Freeze-thaw selection also greatly decreased the abundance and diversity of consortia from distinct sites, and allowed the recovery of individual isolates, many of which demonstrated ice-association. Freeze-thaw selection was also used to assess the role of cross-tolerance between osmotic and freeze-thaw stresses, based on the common challenge of desiccation. Microbial consortia from lakes with varying degrees of salinity were subjected to freeze-thaw stress, and the consortia from more saline lakes tended to show greater low temperature resistance. While few of the recovered microbes demonstrated ice-association activities, those from the more saline lakes tended to contain a higher intracellular solute concentration and were more likely to form biofilms. This underscores the diversity of resistance strategies and supports the notion of cross-tolerance. To determine if these selective regimes would have applications for hydrate growth inhibition, microbes derived from an oil well sample were subjected to freeze-thaw stress. Selection reduced microbial abundance, shifted the diversity, and resulted in the recovery of microbes with some ice-association activity. Taken together, this thesis demonstrates that the application of low temperature stress can be used to successfully investigate stress resistance mechanisms within microbial communities from distinct environments. / Thesis (Ph.D, Biology) -- Queen's University, 2010-09-21 15:58:14.932

No description available.

Pseudomonas Aeruginosa is a common gram-negative bacterium present in the environment. It causes severe infections in immunosuppressed patients. Cystic fibrosis patients are especially at risk of being infected with Pseudomonas Aeruginosa. Ongoing studies are preformed to find alternative therapies to antibiotics, due to increased resistance. One new treatment is intake of specific IgY antibodies against Pseudomonas Aeruginosa as an oral therapy. The problem today is that IgY solutions must be kept frozen until consumed.  In this study we examined the possibility to freeze-dry specific IgY antibodies without losing any activity or specificity of the antibodies. This would be more convenient of patients, as well as it makes transportation and storage easier.  The methods used were ELISA for control of activity, western blot analysis and SDS-PAGE gel for control of specificity. Three different batches of the IgY anti-Pseudomonas Aeruginosa solution were tested. The results showed that no loss in activity occurred that would affect clinical outcome or change of specificity in the antibodies after freeze-drying appears. This indicates that it is possible to replace the liquid antibody to a freeze-dried powder.

In this thesis freeze-thaw along roads in northern Sweden is examined. The examinations are put in a context of changing climate and its amplification towards the Arctic region on earth. The research focuses on the impact of a warmer climate on ground freeze-thaw and in exten- sion road maintenance in the region. The investigation is presented through two scientific papers, where the first examines how ground temperatures are developed during a single frost season experiment, where a natural accumulation of snow cover and a continual removal of snow cover occur respectively. In the second paper, ground temperature data from sub-Arctic Sweden that has been logged by the Swedish Transport Administration, has been collected and freeze-thaw cycles have been calculated and analysed. The results are related to regional landscape factors and are in the context of regional climate change discussed to reach understanding of challenges for road maintenance in the region and opportunities to reach resilience. The results in Paper 1 show that also a thin cover of snow has impact on the freeze-thaw frequency, duration and intensity that occur in and on the surface of the ground. Furthermore the results show that the ground temperatures rise in due to an increase in snow cover amounts and that this process occurs in several steps. Paper 2 shows that the occurrence of ground freeze-thaw is affected by the proximity to open waters. Warmer temperatures in the air may cause later ice freeze-up and earlier ice break-up on lakes, rivers and on the Gulf of Bothnia and roads in northern Sweden are in general situated on the coast or near rivers. Ground temperatures around 0 °C has a high negative impact on road stability and a warmer and wetter climate in northern Sweden may thus increase road deterioration. The economic development in Sweden stays dependent on extraction of natural resources in sub-Arctic Sweden and thus it is of major concern to main- tain and improve road infrastructure in the region.