A major problem associated with the development of complex polymeric materials for food contact applications is the potential for migration of toxic substances from the polymer to the food. This thesis investigates the transfer of migrants from non-ovenable food contact materials at elevated temperatures, and several applications where migration has occurred have been identified. Boil in the bag applications lead to exposure times of 30 - 120 minutes for complex multilayer laminates, whilst plastic kettles are repeat exposure items, and plastic 'vacuum flasks' have a potential for up to 4 hours exposure. Analytical techniques including, GC-MS, LC-MS, HPLC and UV spectroscopy have been employed to quantify the species migrating from these food contact materials into aqueous and oil simulants, and to ensure that they conform to the implemented EC restrictions. Olive oil is a stipulated EC fatty food simulant, but it is unsuitable for specific migration analyses since it contains many interfering compounds. These could not be eliminated by repeated solvent extraction, and a silicone oil was therefore substituted. In an attempt to identify the species migrating into aqueous and fatty food simulants both the final materials and also the individual components i.e. nylon, adhesive, polyethylene and polypropylene were examined separately. HPLC techniques have been developed to quantify both the known levels of antioxidants present in the polymers and also the anticipated degradation products from these materials. Typical levels of antioxidants in simulants range from <0.1 (aqueous) to 45j..lgdm-2 (oil) and <0.1 (aqueous) to 200j..lgdm" (oil) for antioxidant degradation products. In commercial boil in the bag laminates the major migrants have been shown to be derived principally from the nylon film, and the polyurethane adhesive used to fabricate the laminate. Le-MS investigations have confirmed the presence of the residual monomer Ecaprolactarn and its cyclic oligomers (up to the nonarner) in aqueous food simulants boiled in direct contact with the nylon 6. This technique has also identified the main migrants from the aliphatic and aromatic polyurethane adhesives to be residual oligomers from the polyols. Any residual isocyanates in the adhesive are converted to the corresponding amine, and colourimetric assays have determined levels between 1.1 and O.lj..lgdm". Measured, migration levels into fatty food simulants were found to be greater than in aqueous food simulants. However, none of the material examined showed an overall migration value greater than the EC limit of 10mg dm" for single sided testing. Some instances were found where the consumer was instructed to boil the dry food part of a boil in the bag meal in the same water as that used to heat the pouch containing the meat, and under these circumstances a total migration value for the laminate greater than 10mg dm-2 was measured.

The basic aim of barley malt breeders and maltsters is to produce malt with optimum fermentability levels. The purpose of this research was to understand and evaluate the effect of wort boiling and autoclaving at varying time periods (30, 45, 60, 90, and 120 min) on malt fermentability. The effect of trub content was also analyzed. Small-scale fermentations were carried out using a ‘Control malt’ and a standard SMA yeast strain. The Apparent Degree of Fermentability (ADF), Turbidity (absorbance at 600nm), and Density (oPlato) were measured at specific time intervals over three day fermentation period and non-linearly modeled. From the results obtained, we suggest that heat treating wort with or without trub, (at 100°C, 121.1°C) for a range of times results in significant decline in the ADF (p<0.05). Free amino nitrogen levels of wort declined significantly with respect to both increase in wort boiling temperature and intervals (p<0.001).

Sand boil formation due to underseepage is a potential failure mechanism for levees in the Lower Mississippi River Valley. Sand boils were identified in the Buck Chute study area in the 1990s during high water events and during the 2009 Flood. The site is unique due to the presence of point bar and abandoned channel deposits. To understand the role of these alluvial deposits on sand boil formation at the site, a geologic investigation of the subsurface was conducted. Using shallow geophysics, cone penetrometer tests (CPT), borings, and a geographic information system (GIS), it was concluded that the thin blanket associated with point bar deposits, abandoned channel deposits causing a blocked seepage path, and head differential changes caused by the Muddy Bayou Control Structure were the controls of sand boil formation at Buck Chute.

This master thesis project aims to investigate the circumstances of boil-off for heavy vehicle transports, using LNG as fuel, and suggest possible ways of handling these gases otherwise released into the atmosphere. LNG, Liquefied Natural Gas, is when natural gas is cooled below its vaporisation point, turning it into liquid phase which is a much more dense way of storing and transporting the fuel. Trucks running on LNG store their fuel in super insulated tanks, but some heat are transferred to the fuel anyway, causing it to vaporise at a steady rate. During driving of these trucks, this vaporised gas is consumed and the pressure are kept at a certain level of 10 bar. Once the truck is turned off, consumption stops and the pressure starts to increase. After a period of standstill, normally several days, the pressure within the tank has increased to 16 bar where a valve opens to release gas from the tank. This is a safety feature, causing the pressure not to increase further creating hazards. While natural gas, mostly containing methane, is released, fuel is lost and an environmentally unfriendly substance is let out into the atmosphere. This should be avoided, to improve the environmental aspects of using LNG as a fuel for trucks, which most likely will be regulated by laws yet to come. Since the release of boil-off gases rarely should happen during the regular use of these trucks, but a system handling these gases should work at any time and place, a cheap and lightweight unit are to be fitted to these trucks. Equipment already on the truck should be used as much as possible, keeping additional costs and weight low. The only practical way of storing this gas, which is the most resource efficient way of handling these boil-off gases, is to re-liquefy it and transferring it back to the usual LNG tank on the vehicle. The second best option is to consume the gas, making it less environmentally unfriendly. While consuming the gas, as much as possible of its energy should be utilised as electricity and heat. Preferably, electricity should be produced as much as possible, charging the batteries on the truck, decreasing the fuel consumption while running and increasing the lifespan of the batteries. The most efficient way of managing the heat generated is to distribute it to the coolant system on the truck, providing it to the engine and several other components. Distributing the energy is also a matter of safety, as very hot areas otherwise might cause risks of fire. The most simple concept, that is easiest to implement in the near future, is to use a burner similar to the auxiliary diesel heaters fitted to some trucks today. This consumes fuel, generating heat to the coolant system. An additional cooler is needed, to cool of excess heat from the system keeping the temperatures to a certain level. Using this system for an extensive period of time needs an external power supply, since no electricity is generated from consuming the gas. Other technologies that could be used in the future, also generating electricity, is thermoelectric generators and solid oxide fuel cells. These are technologies now being further developed and adapted to the industry of vehicles. These technologies are especially interesting when they are implemented to these trucks for use within other systems as well, for instance utilisation of the heat within exhaust gases. A small scale re-liquefaction unit mounted to the truck is however seen as the most resource efficient solution, making it possible to keep using the gas for it intended purpose of propelling the trucks forward. This technology has to be made more compact, adapting it to the use on a truck.

Moisture susceptibility of hot mix asphalt (HMA) pavements continues to be a major pavement distress. Past research has primarily focused on HMA stripping prevention through material component evaluation/testing and addition of preventative additives. Stripping is caused by traffic, water, and high in-place service temperatures. Today, agencies use various methods to evaluate HMA moisture susceptibility with varying degrees of success. The study objective was to evaluate a prototype stripping simulator?s ability to predict HMA moisture susceptibility. The simulator evaluates moisture susceptibility by measuring conditioning water turbidity. Boil test and indirect tensile strength testing were also conducted for comparison purposes. Stripping simulator results indicate further refinement is required before it can be used for moisture susceptibility prediction.

Rapporté à la tonne de fret, le trafic maritime est un mode de transport relativement « propre ». Néanmoins, par l’intensification des échanges mondiaux, sa part dans les émissions de Gaz à Effet de Serre (GES) au niveau mondial est appelée à augmenter. Conscients des effets néfastes associés aux GES, les pays membres des nations unies, via l’organisation maritime internationale, imposent le cadre réglementaire pour que ce secteur, vital dans une économie mondialisée, demeure écologiquement acceptable. Des objectifs ambitieux sont établis à court (2020) et moyen terme (2050). Or, d’après l’hypothèse faible de Porter, fixer des objectifs environnementaux sans imposer les moyens à mettre en oeuvre favorise l’innovation. Aussi, dans l’industrie du « shipping », les solutions fleurissent au premier rang desquelles figure l’emploi du Gaz Naturel Liquéfié (GNL) en tant que combustible. D’un point de vue thermodynamique, les inévitables infiltrations thermiques à travers les parois des réservoirs cryogéniques entraînent une variation de la pression dans le réservoir et des fluctuations de la qualité du gaz à l’admission moteur. Selon le schéma d’exploitation navire, ces deux phénomènes impactent significativement la pertinence de l’option GNL. En réponse, cette thèse propose un ensemble de modèles 0D pour, à partir d’un profil opérationnel, évaluer :1. l’évolution de la pression dans les réservoirs ;2. l’évolution de la qualité du gaz à l’admission moteur.Dans une première partie, des modèles sont proposés pour simuler les infiltrations thermiques à travers le réservoir, l’évaporation du GNL, son vieillissement (altération des propriétés du gaz par évaporation différenciée des composés) et l’évolution du taux de méthane à l’admission moteur. Puis, les modèles sont assemblés à travers une étude de cas apportée par un acteur du transport maritime. / In proportion to the ton of cargo, shipping is a relatively “clean” transportation mode. Nevertheless, due to global trade intensification, its share in the global greenhouse gas (GHG) emissions should increase. Aware that GHG adverse effects are a major concern for humanity, united nation member states impose, via the international maritime organization, a regulatory framework so that this vital sector in a global economy remains sustainable. Short (2020) and medium (2050)-term goals are set. According to the weak version of Porter’s hypothesis, strict environmental regulations encourage innovations. Hence, in the shipping industry solutions flourish among which the use of Liquefied Natural Gas (LNG) as a fuel. On a thermodynamic basis, the unavoidable heat leaks into the cryogenic tanks cause variations of the tank pressure and the natural gas quality at engine inlet. Depending on the ship’s operational profile, those two phenomena will impact significantly the LNG as a fuel option relevance. One major bottleneck slowing the uptake of LNG as a marine fuel is the lack of methods and models to perform, at a concept design level, the feasibility study. In response, this thesis proposes 0D models to assess from the operational profile:1. the tank pressure evolution;2. the gas quality evolution at engine inlet.In the first part, models are proposed to simulate heat leaks into the tanks, LNG vaporization, ageing (the alteration of natural gas thermophysical properties by a differentiate vaporization of its compounds) and methane number evolution at engine inlet. Then, the models are put together and applied on a case study. The ship concept is proposed by a freight company.

Master of Science / Department of Civil Engineering / Yacoub M. Najjar / Reliable and economical design of Portland Cement Concrete (PCC) pavement structural systems relies on various factors, among which is the proper characterization of the expected permeability response of the concrete mixes. Permeability is a highly important factor which strongly relates the durability of concrete structures and pavement systems to changing environmental conditions. One of the most common environmental attacks which cause the deterioration of concrete structures is the corrosion of reinforcing steel due to chloride penetration. On an annual basis, corrosion-related structural repairs typically cost millions of dollars. This durability problem has gotten widespread interest in recent years due to its incidence rate and the associated high repair costs. For this reason, material characterization is one of the best methods to reduce repair costs. To properly characterize the permeability response of PCC pavement structure, the Kansas Department of Transportation (KDOT) generally runs the Rapid Chloride Permeability test to determine the resistance of concrete to penetration of chloride ions as well as the Boil test to determine the percent voids in hardened concrete. Rapid Chloride test typically measures the number of coulombs passing through a concrete sample over a period of six hours at a concrete age of 7, 28, and 56 days. Boil Test measures the volume of permeable pore space of the concrete sample over a period of five hours at a concrete age of 7, 28, and 56 days. In this research, backpropagation Artificial Neural Network (ANN)-based and Regression-based permeability response prediction models for Rapid Chloride and Boil tests are developed by using the databases provided by KDOT in order to reduce or eliminate the duration of the testing period. Moreover, another set of ANN- and Regression-based permeability prediction models, based on mix-design parameters, are developed using datasets obtained from the literature. The backpropagation ANN learning technique proved to be an efficient methodology to produce a relatively accurate permeability response prediction models. Comparison of the prediction accuracy of the developed ANN models and regression models proved that ANN models have outperformed their counterpart regression-based models. Overall, it can be inferred that the developed ANN-Based permeability prediction models are effective and applicable in characterizing the permeability response of concrete mixes used in transportation applications.

Polar desert environments are limiting in plant available nutrients, mainly nitrogen (N) and phosphorus (P) that severely limit plant growth and establishment. Cryogenic activity regularly patterns the ground into a patchwork of frost boils – sorted circles that are associated with an increase in moisture, fertility and plant cover. Within some frost boils, the accumulation of ice-rich soil at the permafrost table can cause an upward flow of soil organic carbon (SOC) enriched permafrost material into the active layer. These diapiric intrusions are predicted to fuel microbial activity and enrich the horizon in N and P; however, the enrichment of the diapir horizon and accessibility by plants has yet to be studied. The aim of this research was to characterize the N distribution within diapir horizons located in frost boils and the effect of these intrusions on vascular plant N uptake in a polar desert ecosystem of the Canadian High Arctic. Natural abundance and enriched isotope 15N techniques were used to trace the flow of N through the soil-plant system. Surface and diapir horizons contained the highest total C and total N content within frost boils. Natural abundance δ15N analysis indicated that uptake by Salix arctica plants located on frost boils in the absence of a diapir horizon were sourcing N from the surface. However, when diapir nutrients became available, S. arctica plants began sourcing N from the diapir horizon and underlying low SOC sources in the soil, while reducing uptake from the surface. The altered foraging strategy of S. arctica in response to diapir horizon formation was further indicated by significant uptake of atom%15N nutrients that were injected directly into diapir horizons. These findings suggest diapir horizons are enriched in N and accessible by plants roots as an important nutrient source that is instrumental in their survival within frost boils of a polar desert ecosystem in the high arctic.

A análise microbiológica atua como ferramenta fundamental para a obtenção de dados sobre a qualidade, sanidade, higiene e segurança na produção de alimentos; desta forma, tem sido adotada na indústria alimentícia para o controle de qualidade. Por sua composição completa e balanceada, o leite é um substrato ideal para o desenvolvimento de diversos grupos de microrganismos. Com o objetivo de pesquisar bactérias da espécie Bacillus cereus em amostras de leite fluido, bem como a capacidade de germinação de esporos e a multiplicação dessa bactéria após processo de fervura, com manutenção das amostras à temperatura ambiente e à temperatura de refrigeração por períodos de 1, 2, 4, 6, 8, 10 e 12 horas, foram analisadas 75 amostras de leite, conforme as metodologias recomendadas por Silva et al. (2007). Destas, 46 amostras (61,3%) mostraram-se com algum grau de contaminação pela bactéria antes de serem submetidas à fervura. Por sua vez, as amostras mantidas à temperatura ambiente após a fervura, tiveram suas contagens bacterianas, principalmente a partir da 8a hora, superiores à contagem inicial, inclusive atingindo níveis capazes de desencadear uma toxinfecção alimentar, demonstrando a ocorrência da germinação dos esporos e a multiplicação das células vegetativas. Por outro lado, alíquotas dessas mesmas amostras mantidas sob refrigeração (7ºC) não atingiram populações preocupantes, enfatizando, desse modo, a importância da necessidade da refrigeração do leite após a fervura. / The microbiological analysis acts as basic tool for the attainment of data on the quality, health, hygiene and security in the food production, in such a way, she has been adopted in the nourishing industry for the quality control. For its complete and balanced composition, milk is an ideal substratum for the development of diverse groups of microorganisms. With the objective to search cereus bacteria of the Bacillus species in fluid milk samples, as well as the capacity of germination of spores and the multiplication of this bacterium after boil process, with maintenance of the samples to the ambient temperature and the temperature of refrigeration for periods of 1, 2, 4, 6, 8, 10 and 12 hours, 75 milk samples had been analyzed, as the methodologies recommended for Silva et al. (2007). Of these, 46 samples (61.3%) had revealed with some degree of contamination for the bacterium before being submitted to the boil. In turn, the samples kept to the ambient temperature after the boil, had its bacterial countings, mainly from 8a hour, superiors to the initial counting, also reaching levels capable to unchain an alimentary toxinfection, demonstrating to the occurrence of the germination of the spores and the multiplication of the vegetative cells. On the other hand, aliquot of these same samples kept under refrigeration (7ºC) had not reached preoccupying populations, emphasizing, in this manner, the importance of the necessity of the refrigeration of milk after the boil.

The study presents a systematic single and two-phase analysis of fluid flow and heat transfer in a liquid hydrogen storage vessel for both earth and space applications.The study considered a cylindrical tank with elliptical top and bottom. The tank wall ismade of aluminum and a multi-layered blanket of cryogenic insulation (MLI) has been attached on the top of the aluminum. The tank is connected to a cryocooler to dissipate the heat leak through the insulation and tank wall into the fluid within the tank. The cryocooler has not been modeled; only the flow in and out of the tank to the cryocooler system has been included. The primary emphasis of this research has been the fluid circulation within the tank for different fluid distribution scenario and for different level of gravity to simulate all potential earth and space based applications. The equations solved in the liquid region included the conservation of mass, conservation of energy, and conservation of momentum. For the solid region only the heat conduction equation was solved. The steady-state velocity, temperature and pressure distributions were calculated for different inlet positions, inlet opening sizes, inlet velocities and for different gravity values. The above simulations were carried out for constant heat flux and constant wall temperature cases. It was observed from single-phase analysis that a good flow circulation can be obtained when the cold entering fluid was made to flow in radial direction and the inlet opening was placed close to the tank wall. For a two-phase analysis the mass and energy balance at the evaporating interface was taken into account by incorporating the change in specific volume and latent heat of evaporation. A good flow circulation in the liquid region was observed when the cold entering fluid was made to flow at an angle to the axis of the tank or aligned to the bottom surface of the tank. The fluid velocity in the vapor region was found to be higher compared to the liquid region. The focus of the study for the later part of the present investigation was the conjugate heat transfer during a confined liquid jet impingement on a uniform and discrete heating source. Equations governing the conservation of mass, momentum, and energy were solved in the fluid region. In the solid region, the heat conduction equation was solved. The solid-fluid interface temperature shows a strong dependence on several geometric, fluid flow, and heat transfer parameters. For uniform and discrete heat sources the Nusselt number increased with Reynolds number. For a given flow rate, a higher heat transfer coefficient was obtained with smaller slot width and lower impingement height.The average Nusselt number and average heat transfer coefficient are greater for a lower thermal conductivity substrate. A higher heat transfer coefficient at the impingement location was seen at a smaller thickness, whereas a thicker plate or a higher thermal conductivity plate material provided a more uniform distribution of heat transfer coefficient. Compared to Mil-7808 and FC-77, ammonia provided much smaller solidfluid interface temperature and higher heat transfer coefficient whereas FC-77 provided lower Nusselt number. In case of discrete heat sources calculations were done for two different physical conditions, namely, when the total input power is constant and when the magnitude of heat flux at the sources are constant. There was a periodic rise and fall of interface temperature along the heated and unheated regions of the plate when the plate thickness was negligible. The average Nusselt number and average local heat transfer coefficient were highest for uniform heating case and it increased with number of heat sources during discrete heating.