O uso de princípios ativos a base de plantas em alimentos pode ser interessante devido à sua atividade (ex.: antioxidante, antimicrobiana, dentre outros), entretanto, alguns desses aditivos são hidrofóbicos, sendo, portanto, de difícil dispersão na formulação do alimento, que é geralmente rico em água. Do mesmo modo, a diminuição da concentração utilizada de antisépticos é um desafio atual. Uma alternativa é a utilização desses princípios ativos na forma de nanoemulsões com baixas concentrações de princípios ativos. O objetivo geral desta tese foi o desenvolvimento de nanoemulsões a base de eugenol e extrato de pimenta dedo-demoça para uso em alimentos, e a base de triclosan, para uso tópico, como alternativa para higienização de mãos de manipuladores de alimentos. O desenvolvimento das nanoemulsões foi realizado com o auxílio de um homogeneizador de alta velocidade seguido de um homogeneizador de alta pressão. Foram estudados os seguintes parâmetros, em vários experimentos: tipo e concentração de tensoativos, valor ideal de HLB, relação fase lipídica/fase aquosa, relação tensoativo/óleo, e composição e processo. As nanoemulsões foram otimizadas por desenho experimental, avaliadas quanto à estabilidade por estresse térmico e força centrífuga e estabilidade ao armazenamento por 90 dias, caracterizadas por diferentes análises, incluindo a determinação do potencial antioxidante e antibacteriano. Foram desenvolvidas nanoemulsões com tamanho médio de gota menor que 200 nm, sendo que, a estabilidade frente ao estresse térmico e força centrífuga variaram para cada sistema, mas, todas nanoemulsões foram estáveis pelo período de 90 dias em temperatura ambiente. A nanoemulsão de eugenol demonstrou bom potencial antioxidante e a nanoemulsão de triclosan demonstrou alta atividade bacteriostática na concentração de 3% e atividade bactericida em concentração menor que 40µg/mL pelo período de 90 dias. As nanoemulsões desenvolvidas têm potencial de aplicação nas indústrias de alimentos e sanitária. / The utilization of plant bioactives in food can be interesting because of its activity (eg.: antioxidant, antimicrobial, among others) and to minimize the use of their high concentration of antiseptics. However, some of these additives are hydrophobic, and, therefore, are more difficult to be dispersed in food, which are generally water-based. A good alternative is the use of low concentration of these actives as nanoemulsions. The aim of this thesis was the development of nanoemulsions with eugenol, \"dedo-de-moça\" pepper extract for food applications, and of triclosan for topical application as hand\'s cleaner. The studies for development of these nanoemulsions were carried out with a high speed homogenizer followed by a high pressure homogenizer. The following parameters were tested: type and concentration of surfactants, ideal HLB value, lipid phase/aqueous phase relation, surfactant/oil relation, and composition and processing conditions. Nanoemulsions were optimized by experimental design, evaluated by preliminary and storage stability, characterized by different analysis, including antioxidant and antimicrobial activities. Nanoemulsions with mean droplet size lower than 200 nm were developed; the thermal stress and centrifuge stabilities were different for each system, but, all nanoemulsions were stable over 90 days on ambient temperature. The eugenol nanoemulsion had good antioxidant activity and triclosan nanoemulsion had high antimicrobial activity in the concentration of 3% and a bactericidal activity at concentration lower than 40µg/mL over 90 days period. The nanoemulsions developed have potential for applications in food and sanitary industries.

Purpose:Development of a stability-indicating high-performance liquid chromatography (HPLC) method for pyrimethamine analysis, with subsequent application of that method to assess the 90-day stability of a pyrimethamine suspension compounded from bulk USP-grade pyrimethamine powder, is described. Methods:A stability-indicating method of HPLC with ultraviolet detection specific to pyrimethamine was developed according to pharmacopeial recommendations and validated. The method was applied to investigate the stability of a 2-mg/mL pyrimethamine suspension in a vehicle consisting of Ora-Plus and Ora-Sweet (Perrigo) over a period of 90 days. Three replicate test preparations were stored at room temperature or refrigerated at 4.3–5.2 °C, and samples were analyzed in duplicate immediately after preparation and on study days 1, 2, 4, 7, 10, 14, 21, 30, 48, 60, 75, and 90. Results:The 2-mg/mL suspension of pyrimethamine in Ora-Plus and Ora-Sweet retained 90–110% of the labeled potency to 90 days at both temperature ranges. However, color changes in the samples stored at room temperature observed at day 60 indicated that a beyond-use date less than 90 days from the preparation date should be specified when the suspension is to be stored at room temperature. Conclusion:The study demonstrated that USP-grade pyrimethamine powder can be formulated as a 2-mg/mL suspension in a vehicle of Ora-Plus and Ora-Sweet and is stable when stored at room temperature and when refrigerated, in amber plastic bottles, for 48 and 90 days, respectively.

High-pressure needleless injection (HPNI) is a process where small-diameter, high-velocity burst of liquid, penetrate foods at pressures ≤ 10,000 psi. The potential of HPNI as an enhancing technique for meat was studied. In study 1, HPNI translocated surface E. coli O157 into the interior of beef eye-of-round subprimals with an incidence of 40 (±7), 25 (±8), and 25 (±8)% for meat that had been surface-inoculated with a four-strain cocktail at 0.5, 1, and 2 log10 CFU/cm2, respectively. Run-off water contained 2, 2, and 3 log10 CFU/ml and was used for HPNI of additional subprimals, which resulted in a cross-contamination incidence of 83 (±4), 60 (±15), and 37 (±6) %, respectively. Incidence of translocation and cross-contamination was similar at all sampled levels below the inoculated surface. Study 1 results indicate that surface microflora will be translocated from the surface into the interior of HPNI-treated beef by the injection fluid and by cross-contamination with recycled fluid. In study 2, E. coli was undetected in cooked steaks (63˚C internal) cut from subprimals inoculated with 2 log10 CFU/cm2 and HPNI processed (study 1). Although cooking reduced E. coli counts, determination of complete kill was not possible because the detection limit for bacterial recovery was about 1 log10 CFU/g. Steaks cut from HPNI-processed subprimals took longer (p <0.05) to reach 63˚C with grilling or broiling, compared to control steaks, possibly due to increased moisture in enhanced steaks. In study 3, sensory acceptance of steaks was evaluated by a consumer panel. Appearance, flavor, and overall acceptance were similar among the untreated control, HPNI steaks, blade tenderized steaks (BT steaks), and steaks cut from subprimals that had been needle-injected with 0.35% (wt/vol) sodium tripolyphosphate using needle injection (NI-subprimal steaks) or HPNI (HPNI-subprimal steaks). Texture of BT steaks (6.5±1.9) was more liked than control steaks (5.8±1.8), while texture was similar for all other comparisons. Conversely, Warner-Bratzler shear force was NI-subprimal steaks < control < HPNI steaks = HPNI-subprimal steaks = BT steaks. Lack of correspondence between texture acceptance data and WBSF suggests that sensory scores were influenced by factors other than the force required for mechanical shear.

No description available.

No description available.

Fiordland is located southwest of South Island of New Zealand. The field area of this thesis is in northern Fiordland, at the boundary of pristine arc rocks (Median Tectonic Zone) and a belt of Paleozoic paragneisses and orthogneisses of variable age that represent the metamorphosed paleo-Pacific Gondwana margin.

<p>The objective of this work has been to study equilibrium and non equilibrium situations during high pressure gas processing operations with emphasis on utilization of the high reservoir pressure. The well stream pressures of some of the condensate and gas fields in the North Sea are well above 200 bar. Currently the gas is expanded to a specified processing condition, typically 40-70 bar, before it is recompressed to the transportation conditions. It would be a considerable environmental and economic advantage to be able to process the natural gas at the well stream pressure. Knowledge of thermodynamic- and kinetic properties of natural gas systems at high pressures is needed to be able to design new high pressure process equipment. </p><p>Nowadays, reactive absorption into a methyldiethanolamine (MDEA)solution in a packed bed is a frequently used method to perform acid gas treating. The carbon dioxide removal process on the Sleipner field in the North Sea uses an aqueous MDEA solution and the operation pressure is about 100 bar. The planed carbon dioxide removal process for the Snøhvit field in the Barents Sea is the use of an activated MDEA solution. </p><p>The aim of this work has been to study high-pressure effects related to the removal of carbon dioxide from natural gas. Both modelling and experimental work on high-pressure non-equilibrium situations in gas processing operations have been done. </p><p>Few experimental measurements of mass transfer in high pressure fluid systems have been published. In this work a wetted wall column that can operate at pressures up to 200 bar was designed and constructed. The wetted wall column is a pipe made of stainless steel where the liquid is distributed as a thin liquid film on the inner pipewall while the gas flows co- or concurrent in the centre of the pipe. The experiments can be carried out with a well-defined interphase area and with relatively simple fluid mechanics. In this way we are able to isolate the effects we want to study in a simple and effective way. </p><p>Experiments where carbon dioxide was absorbed into water and MDEA solutions were performed at pressures up to 150 bar and at temperatures 25 and 40°C. Nitrogen was used as an inert gas in all experiments. </p><p>A general non-equilibrium simulation program (NeqSim) has been developed. The simulation program was implemented in the object-oriented programming language Java. Effort was taken to find an optimal object-oriented design. Despite the increasing popularity of object-oriented programming languages such as Java and C++, few publications have discussed how to implement thermodynamic and fluid mechanic models. A design for implementation of thermodynamic, mass transfer and fluid mechanic calculations in an object-oriented framework is presented in this work. </p><p>NeqSim is based on rigorous thermodynamic and fluid mechanic models. Parameter fitting routines are implemented in the simulation tool and thermodynamic-, mass transfer- and fluid mechanic models were fitted to public available experimental data. Two electrolyte equations of state were developed and implemented in the computer code. The electrolyte equations of state were used to model the thermodynamic properties of the fluid systems considered in this work (non-electrolyte, electrolyte and weak-electrolyte systems).</p><p>The first electrolyte equation of state (electrolyte ScRK-EOS) was based on a model previously developed by Furst and Renon (1993). The molecular part of the equation was based on a cubic equation of state (Scwarzentruber et.al. (1989)’s modification of the Redlich-Kwong EOS) with the Huron-Vidal mixing rule. Three ionic terms were added to this equation – a short-range ionic term, a long-range ionic term (MSA) and a Born term. The thermodynamic model has the advantage that it reduces to a standard cubic equation of state if no ions are present in the solution, and that public available interaction parameters used in the Huron-Vidal mixing rule could be utilized. The originality of this electrolyte equation of state is the use of the Huron-Vidal mixing rule and the addition of a Born term. Compared to electrolyte models based on equations for the gibbs excess energy, the electrolyte equation of state has the advantage that the extrapolation to higher pressures and solubility calculations of supercritical components is less cumbersome. The electrolyte equation of state was able to correlate and predict equilibrium properties of CO₂-MDEA-water solutions with a good precision. It was also able to correlate high pressure data of systems of methane-CO₂-MDEA and water. </p><p>The second thermodynamic model (electrolyte CPA-EOS) evaluated in this work is a model where the molecular interactions are modelled with the CPA (cubic plus association) equation of state (Kontogeorgios et.al., 1999) with a classical one-parameter Van der Walls mixing rule. This model has the advantage that few binary interaction parameters have to be used (even for non-ideal solutions), and that its extrapolation capability to higher pressures is expected to be good. In the CPA model the same ionic terms are used as in the electrolyte ScRK-EOS. </p><p>A general non-equilibrium two-fluid model was implemented in the simulation program developed in this work. The heat- and mass-transfer calculations were done using an advanced multicomponent mass transfer model based on non-equilibrium thermodynamics. The mass transfer model is flexible and able to simulate many types of non-equilibrium processes we find in the petroleum industry. A model for reactive mass transfer using enhancement factors was implemented for the calculation of mass transfer of CO₂ into amine solutions. The mass transfer model was fitted to the available mass transfer data found in the open literature. </p><p>The simulation program was used to analyse and perform parameter fitting to the high pressure experimental data obtained during this work. The mathematical models used in NeqSim were capable of representing the experimental data of this work with a good precision. From the experimental and modelling work done, we could conclude that the mass transfer model regressed to pure low-pressure data also was able to represent the high-pressure mass transfer data with an acceptable precision. Thus the extrapolation capability of the model to high pressures was good. </p><p>For a given partial pressure of CO₂ in the natural gas, calculations show a decreased CO₂ capturing capacity of aqueous MDEA solutions at increased natural gas system pressure. A reduction up to 40% (at 200 bar) compared to low pressure capacity is estimated. The pressure effects can be modelled correctly by using suitable thermodynamic models for the liquid and gas. In a practical situation, the partial pressure of CO₂ in the natural gas will be proportional to the total pressure. In these situations, it is shown that the CO₂ capturing capacity of the MDEA solution will be increased at rising total pressures up to 200 bar. However, the increased capacity is not as large as we would expect from the higher CO₂ partial pressure in the gas.</p><p>The reaction kinetics of CO₂ with MDEA is shown to be relatively unaffected by the total pressure when nitrogen is used as inert gas. It is however important that the effects of thermodynamic and kinetic non- ideality in the gas and liquid phase are modelled in a consistent way. Using the simulation program NeqSim – some selected high-pressure non-equilibrium processes (e.g. absorption, pipe flow) have been studied. It is demonstrated that the model is capable of simulating equilibrium- and non-equilibrium processes important to the process- and petroleum industry.</p>

<p>Crystallization of C₆₀ and C₇₀ from organic solution often leads to the formation of new solvates and other fullerene compounds. In the present thesis, a number of such solvates were obtained and their phase transitions studied using <i>in situ</i> "in solution" techniques. New fullerene materials can be also obtained using High Pressure High Temperature (HPHT) treatment. The formation of C₆₀ polymers in thin films and bulk samples has been studied in situ over a wide pressure-temperature range.</p><p>New methods for single-crystal growth of fullerenes and their compounds have been developed. It was found by <i>in situ</i> "in solution" XRD and Raman spectroscopy that solvate C₆₀ crystals with benzene, toluene and hexane are stable only in equilibrium with their solution. Their melting points coincide with the maximum in the temperature dependence of solubility. C₇₀ solvates grown from these solutions are stable out of solution, and decompose above the boiling points of the solvents. Vibrational signatures were found for the C₆₀ and C₇₀ solvates which are very similar to these for fullerene-sulfur compounds obtained as thin films and single crystals. A new C₇₀S₈ compound was obtained as relatively large single crystals. </p><p>C₆₀ polymerisation under HPHT conditions was studied on thin films and showed a thickness effect on the phase transition around 20 GPa. Superhard and superelastic films were obtained by treatment at 23 GPa and 570K. In situ Raman and XRD studies were performed on bulk samples at pressures up to 27 GPa and temperatures up to 850K. Below 13 GPa, only one- and two-dimensional polymers were found to form during the heating. The observed polymerisation pathway suggests a gradual increase in polymerisation. Above 18 GPa, the <i>in situ</i> Raman spectra obtained during heating remained almost unchanged. The XRD study showed that heating at 830K and 13 GPa leads to the formation of a rhombohedral phase with a volume per C₆₀ molecule of 560-570 ų/M, which is below the value for two-dimensional polymers. Nevertheless, no superhard, highly dense phases were observed under these conditions, in contrast to previous studies.</p>

<p>Knowledge about the stability of phases and their relationships in the Fe-O system at high pressures and temperatures is essential in implications of the multifarious states of iron oxides for models of the evolution of the Earth. In this respect, the iron ferrite magnetite (FeFe₂O₄) plays a significant role since it participates in the control of geochemistry of ferric iron, and hence oxygen fugacity in the Earth`s deep interior.</p><p>High-pressure experiments on Fe₃O₄ were performed using the diamond anvil cell technique combined with the laser and electrical resistive heating. The approach based on the combination of the synchrotron x-ray diffraction with Raman spectroscopic measurements benefited from the complementarity of the two methods originating from the different sensitivity to a range of structural order. High-pressure transformation of magnetite to a dense polymorph of the CaTi₂O₄-type structure proceeds via an intermediate step of the decomposition into a mixture of oxides on a microscopic scale. The kinetic hindrance of the reaction of the decomposition effectively prevents a phase separation controlled by diffusion and restricts the formation of the daughter products to locally ordered structures in the strained lattice of magnetite.</p><p>Thermodynamic analysis of the observed phase transformations along with published results on the elastic properties and pressure-induced transitions of iron oxides has led to the reassessment of the phase diagram of Fe₃O₄. The pressure - temperature field of its stability with respect to the breakdown to a mixture of oxides FeO and Fe₂O₃, and to the transition to a high-pressure form, has been accordingly modified.</p>

Crystallization of C60 and C70 from organic solution often leads to the formation of new solvates and other fullerene compounds. In the present thesis, a number of such solvates were obtained and their phase transitions studied using in situ "in solution" techniques. New fullerene materials can be also obtained using High Pressure High Temperature (HPHT) treatment. The formation of C60 polymers in thin films and bulk samples has been studied in situ over a wide pressure-temperature range. New methods for single-crystal growth of fullerenes and their compounds have been developed. It was found by in situ "in solution" XRD and Raman spectroscopy that solvate C60 crystals with benzene, toluene and hexane are stable only in equilibrium with their solution. Their melting points coincide with the maximum in the temperature dependence of solubility. C70 solvates grown from these solutions are stable out of solution, and decompose above the boiling points of the solvents. Vibrational signatures were found for the C60 and C70 solvates which are very similar to these for fullerene-sulfur compounds obtained as thin films and single crystals. A new C70S8 compound was obtained as relatively large single crystals. C60 polymerisation under HPHT conditions was studied on thin films and showed a thickness effect on the phase transition around 20 GPa. Superhard and superelastic films were obtained by treatment at 23 GPa and 570K. In situ Raman and XRD studies were performed on bulk samples at pressures up to 27 GPa and temperatures up to 850K. Below 13 GPa, only one- and two-dimensional polymers were found to form during the heating. The observed polymerisation pathway suggests a gradual increase in polymerisation. Above 18 GPa, the in situ Raman spectra obtained during heating remained almost unchanged. The XRD study showed that heating at 830K and 13 GPa leads to the formation of a rhombohedral phase with a volume per C60 molecule of 560-570 Å3/M, which is below the value for two-dimensional polymers. Nevertheless, no superhard, highly dense phases were observed under these conditions, in contrast to previous studies.