<blockquote><div><div>Methods and techniques for tailoring the surface morphology of metallic surfaces are determined in part by the complex behavior of elemental interactions in conjunction with electrochemical reactions. In this work, we show how the surface morphology can be predicted based on experimental data resulting from polarization curves and compositional differences of Fe- and Ni-based superalloys. Electrochemical treatments utilizing NaCl as the electrolyte were adapted using parameters such as the pitting resistance equivalent (PRE) number and polarization curves to obtain both rough and smooth surfaces. Utilizing these metrics, we electrochemically etched Inconel 600, SS304, Inconel 718 and Inconel 625 obtaining average surface roughness values that ranged from 0.05 to 57.4 μm indicating the success of tailoring the technique to obtaining rough and smooth surfaces. The effect of current density, current pulsing, and temperature were varied to elucidate roughness and pitting behavior, and strong correlations to the PRE number and polarization curve properties of the alloy were observed. Heat treatments and subsequent evolution to the microstructure in the form of grain growth and precipitation altered the etching behavior. These techniques can be used in preventing corrosion failure and enhancing electrochemical machining</div></div></blockquote>

Aqueous electrolyte solutions at temperature and pressure conditions near the critical point of water are difficult to describe using traditional equations of state based upon the excess Gibbs energy. Models based upon the residual Helmholtz energy have proven more effective. Anderko and Pitzer1 developed a residual Helmholtz energy model (AP) for aqueous electrolyte solutions in which the electrolyte is assumed to be fully associated. The model has been effectively used in describing densities and vapor-liquid equilibria for simple electrolyte systems. The model is less effective for describing enthalpic properties such as heats of dilution. Oscarson and coworkers2, 3 modified the AP model for NaCl solutions by adding a term accounting for the change in Helmholtz energy as a result of aqueous dissociation reactions. This new model, called the RI model, is more accurate than the AP model at conditions where the NaCl dissociates more fully into ions. Liu et. al4, 5 modified the RI model by adding a term to describe interactions between ions in solution and by regressing new model parameter values. This new model, called the RIII model, is more accurate than both the AP model and the RI model and may be used to predict species concentrations in solution as a result of aqueous phase reactions. The RIII model has substantial thermodynamic inconsistencies, however, and is poorly suited for describing mixed solute solutions. This dissertation presents the RIV model which is an electrolyte solution model for solutions in the ranges of 350 °C to 400 °C and 18 MPa to 40 MPa. The RIV model has been applied to aqueous NaCl solutions and aqueous LiCl solutions. The RIV model is a modification of the AP model and includes aqueous phase reactions implicitly through fundamental species interactions. The RIV model is thermodynamically consistent. It is capable of describing densities and heats of dilution. Density predictions from the RIV model are less accurate than the AP model predictions (6.66 % error vs. 3.51 % error) but are reasonable. The heats of dilution predictions from the RIV model are much more accurate than those from the AP model (25.16 % error vs. 78.78 % error). Predictions of the ionic species concentration from the RIV model are likely to be poor as indicated by the poor agreement between experimental values and calculated values of equilibrium constants valid at infinite dilution. In order to provide the necessary data from which to regress the parameters of the RIV model, experimental heat of dilution values were determined using flow calorimetry techniques. These values are also reported in this dissertation.

No description available.

Högt saltintag har traditionellt kopplats till ökad risk för hypertoni, särskilt bland vissa grupper. I detta arbete utforskas relationen mellan saltintag och blodtryck genom en systematisk litteraturgenomgång av randomiserade kontrollerade studier, med fokus på friska individer. Syftet är att utvärdera om och i vilken omfattning saltkonsumtion påverkar blodtrycksnivåerna hos denna population. Studien bygger på litteratursökning i PubMed där relevanta artiklar identifieras med hjälp av sökorden ((high-salt) OR (high-sodium)) AND ((hypertension) OR (blood pressure) AND (healthy). En analys av 17 studier visar att effekten av saltintag på blodtrycket är försumbar eller obefintlig hos friska individer. Dessa resultat betonar behovet av att skilja mellan olika grupper avseende kostrekommendationer och pekar på att individuella skillnader, inklusive saltkänslighet, kan vara avgörande. Diskussionen lyfter fram komplexiteten i förhållandet mellan salt och blodtryck och det är svårt att dra slutsatser om de långsiktiga effekterna av en hög saltkonsumtion. Det understryker att vikten av ytterligare forskning för att klargöra sambandet mellan saltkonsumtion och kardiovaskulär hälsa över olika populationer. / High salt intake has traditionally been linked to an increased risk of hypertension, particularly among certain groups. In this work, the relationship between salt intake and blood pressure is explored through a systematic literature review of randomized controlled trials, focusing on healthy individuals. The aim is to evaluate whether and to what extent salt consumption affects blood pressure levels in this population. The study is based on a literature search in PubMed where relevant articles are identified using the search terms ((high-salt) OR (high-sodium)) AND ((hypertension) OR (blood pressure) AND (healthy)). An analysis of 17 studies shows that the effect of salt intake on blood pressure is negligible or nonexistent in healthy individuals. These results emphasize the need to differentiate between different groups regarding dietary recommendations and point out that individual differences, including salt sensitivity, may be crucial. The discussion highlights the complexity of the relationship between salt intake and blood pressure, and it is difficult to draw conclusions about the long-term effects of high salt consumption. It underlines the importance of further research to clarify the relationship between salt consumption and cardiovascular health across different populations.

We present 2-D numerical simulations of two phase flow in seafloor hydrothermal systems using the finite control volume numerical scheme FISHES. The FISHES code solves the coupled non-linear equations for mass, momentum, energy, and salt conservation in a NaCl-H2O fluid to model the seafloor hydrothermal processes. These simulations use homogeneous box geometries at a fixed seafloor pressure of 25 MPa with constant bottom temperature boundary conditions that represent a sub-axial magma chamber to explore the effects of permeability, maximum bottom temperature and system depth on the evolution of vent fluid temperature and salinity, and heat output. We also study the temporal and spatial variability in hydrothermal circulation. The two-phase simulation results show that permeability plays an important role in plume structure and heat output of hydrothermal systems, but it has little effect on vent fluid temperature and salinity, given the same bottom temperature. For some permeability values, multiple plumes can vent at the seafloor above the simulated magma chamber. Temporal variability of vent fluid temperature and salinity and the complexity of phase separation suggest that pressure and temperature conditions at the top of the axial magma chamber cannot be easily inferred from vent fluid temperature and salinity alone. Vapor and brine derived fluids can vent at the seafloor simultaneously, even from neighboring locations that are fed by the same plume. / Master of Science

In many geologic environments, fluids have compositions that are approximated by the H₂O-NaCl system. When minerals grow in the presence of such fluids, some of the solution is trapped in the growing mineral as fluid inclusions. The salinity, temperature of homogenization, and pressure of homogenization are required to predict the trapping conditions of the fluid inclusion. In the laboratory the salinity and the temperature of homogenization of the trapped fluid are easily determined however, the pressure of homogenization cannot be determined directly, and must be calculated from an equation of state. A statistical model that relates the vapor pressure of H₂O-NaCl to the fluid temperature and composition has been developed. The model consists of equations that predict the vapor pressure of H₂O-NaCl from the eutectic temperature (-21.2°C) to 1500°C and for all compositions between the pure end-members. The model calculates the vapor pressure based on the composition (wt% NaCl) and the temperature of homogenization, which can be directly obtained from laboratory studies of fluid inclusions. This information in turn can be used to construct the isochore, or line of constant volume, along which the fluid inclusion was trapped. Finally the isochore can be used to determine the temperature and pressure at which the host mineral of the fluid inclusion was trapped. / Master of Science

Le but de cette étude est de développer une méthodologie permettant d'obtenir le pH des paléofluides du système H2O-CO2-HCO3--NaCl dans leurs conditions P-T de circulation. Ceci combine une approche expérimentale pour le calibrage d'une méthode analytique, la spectrométrie Raman et une modélisation numérique pour l'interprétation quantitative des équilibres de phase ou d'espèces chimiques. Les techniques analytiques utilisées en routine pour l'étude des inclusions fluides, comme la microthermométrie et la micro-spectrométrie Raman sont utilisées pour la détermination des concentrations. Les expériences sont basées à la fois sur l'utilisation d'inclusions fluides synthétiques fabriquées dans des cristaux de quartz et sur une nouvelle méthode de synthèse de fluides dans des capillaires de silice pure. La technique des fluides contenus dans des capillaires de silice pure peut être appliquée dans une gamme de pressions, jusqu'à 2 ou 3 Kbar à température ambiante, et de températures au moins jusqu'à 400°C sous 2 Kbar de pression. Le protocole expérimental de chargement des fluides du système H2O-CO2-HCO3--NaCl et les méthodes de quantification sont élaborées et validées. La modélisation numérique est basée sur le modèle de Pitzer pour décrire la phase liquide aqueuse, en particulier les coefficients d'activité de chaque espèce chimique des espèces présentes dans la phase aqueuse. L'équation d'état de Duan est utilisée pour le calcul des propriétés P-V-T-X des phases liquide et vapeur dans le sous-système H2O-CO2-NaCl. Les conditions d'application du modèle de Pitzer dans le champ température-pression sont respectivement comprises entre 273 et 523 K et 0 et 2000 bar. La gamme de concentration en NaCl de notre modèle est comprise entre 0 et 5 molal, gamme qui correspond aux températures de fusion de la glace (Tmice) comme dernière phase. La détermination de la concentration des espèces HCO3- et CO2 est réalisée à l'aide de la micro-spectrométrie Raman et est calibrée grâce à l'utilisation des standards que sont les inclusions fluides synthétiques et la technique des capillaires de silice fondue. Un programme de calcul utilisant les modèles de Pitzer et de Duan est réalisé afin d'interpréter i) la température de fusion de la glace et la concentration en bicarbonate en termes de concentration de NaCl et ii) la température d'homogénéisation globale en termes de volume molaire global et de pression à la température d'homogénéisation. Ensuite, la spéciation du fluide est calculée le long de l'isochore à la température de piégeage si celle-ci est inférieure à 250°C. Une première application au gisement d'or de Mokrsko dans le massif de Bohême est discutée / The aim of this study is to develop the methodology to get the pH values of the palaeo-circulation in the system H2O-CO2-HCO3--NaCl in the P-T conditions of circulation. It combines the use of an experimental approach for calibrating the analytical method, Raman spectrometry, and numerical modelling for the quantitative interpretation of phase and chemical species equilibria. The routine analytical techniques for fluid inclusions are used to carry out the experimental analyses, such as microthermometry and micro-Raman spectroscopy. Experiments are based both on the use of synthetic fluid inclusions produced in quartz crystal and a new method to make synthetic fluids in fused-silica glass capillary. The synthetic fluid in silica glass capillary can be applied to a wide range of pressure (up to 2 to 3 kbar) at room temperature and temperature (as high as at least 673 K). The experimental protocol of capillary loading with different chemical species in the system H2O-CO2-HCO3--NaCl and the methods to quantify their amount are elaborated and validated. Numerical modelling is based on the use of the Pitzer model to describe the liquid aqueous phase, especially the activity coefficients of each chemical species in the liquid aqueous phase. The Duan equation of state is used for the P-V-T-X properties of the liquid and vapour phases in the simplified subsystem H2O-CO2-NaCl. The application pressure and temperature ranges of the model are respectively 273 to 523 K, and 0 to 2000 bar. Range of NaCl concentration is between 0 and 5 molal and corresponds to the range of ice melting temperature (Tmice). The determination of the concentration of aqueous species HCO3- and CO2 is performed by using micro-Raman spectrometry and is calibrated with using the standards of synthetic fluid inclusion and silica glass capillary. A software program based on the Pitzer and Duan models has been done for the interpretation of i) ice melting temperature (Tmice) and bicarbonate concentration in terms of NaCl concentration, and ii) total homogenisation temperature in terms of bulk molar volume and pressure at homogenisation temperature. Then speciation of the fluid is calculated along the isochore till the trapping temperature if lower than 250 °C. A first application to the Mokrsko gold deposit in Bohemian Massif is done and discussed

Submitted by Jorge Silva (jorgelmsilva@ufrrj.br) on 2016-10-05T18:21:53Z No. of bitstreams: 1 2016 - Jo?o Pedro Chalfun Haouche Meneses.pdf: 6719960 bytes, checksum: ac9a27b5731b19e4693f71fae09adefe (MD5) / Made available in DSpace on 2016-10-05T18:21:53Z (GMT). No. of bitstreams: 1 2016 - Jo?o Pedro Chalfun Haouche Meneses.pdf: 6719960 bytes, checksum: ac9a27b5731b19e4693f71fae09adefe (MD5) Previous issue date: 2016-01-25 / Petrobras / The drilling of wells in salt layers faces major challenges in Brazil?s oil industry. Drilling in such layers requires the development of new technologies and operational procedures to make the process economically viable. One of the main problems is the dissolution of the salt layers in water-based drilling fluids. An uncontrolled dissolution presents a potential risk for the operation and can cause abrupt changes in the properties of the fluids. The main objective of this work was to study the effects of the dissolution of sodium chloride particles in non-Newtonian fluids containing xanthan gum. The study was divided into three parts, rheological experiments, kinetics experiments in a mixing tank and a mathematical modeling. The rheological experiments aimed at studies of the effect of the addition of saline particles on the rheology of non-Newtonian fluids, the effect of the concentration of suspended particles in the rheology of saturated fluids and the effect of the size of suspended particles in the rheology of saturated fluids. The Einstein equation was used to calculate the apparent viscosity of saturated fluids, taking into account the effect of the concentration of salt particles in suspension. The experiments in the mixing tank aimed at the study of the kinetics of dissolution with time in different operating conditions. Fluids were prepared using different concentrations of xanthan gum and different initial concentrations of sodium chloride. The effects of the viscosifier concentration and the initial concentration gradient were evaluated. A phenomenological model was used to represent the dissolution process, which provides the variation of the concentration of the fluid, the variation of the volume fraction of solids, the variation of the particles mean diameter and the variation of the interfacial mass transfer area as a function of time. In the rheology studies, it was verified that the addition of sodium chloride to the non-Newtonian fluid, in the studied conditions, increased the apparent viscosity of the solution. The increase of the concentration of suspended sodium chloride particles increased the apparent viscosity of the suspensions. The increase of the size of the suspended particles decreased the apparent viscosity of the suspension. Statistical tests were made in order to evaluate the statistical relevance of the performed studies. In the kinetics study, the convective mass transfer coefficient was estimated and simulations were made for the other variables of the process. The estimations showed that the xanthan gum concentration in the fluid and the initial sodium chloride concentration in the fluid affect the mass transfer coefficient. The average relative error observed for the simulations was 2,2%. / A perfura??o de po?os em camadas salinas enfrenta grandes desafios na ind?stria de petr?leo do Brasil. A perfura??o em tais camadas exige o desenvolvimento de novas tecnologias e procedimentos operacionais para tornar a perfura??o economicamente vi?vel. Um dos principais problemas enfrentados ? a dissolu??o das camadas de sais em fluidos de perfura??o base ?gua. Uma dissolu??o descontrolada apresenta um risco em potencial para a opera??o, podendo causar mudan?as bruscas nas propriedades dos fluidos. Este trabalho teve como principal objetivo estudar os efeitos da dissolu??o de part?culas de cloreto de s?dio em fluidos n?o-Newtonianos contendo goma xantana. O estudo foi dividido em tr?s partes, experimentos reol?gicos, experimentos de cin?tica em um tanque de mistura e modelagem matem?tica. Os experimentos reol?gicos tiveram como objetivo os estudos do efeito da adi??o de part?culas salinas na reologia de fluidos n?o-Newtonianos, do efeito da concentra??o de part?culas suspensas na reologia de fluidos saturados e do efeito do tamanho das part?culas suspensas na reologia de fluidos saturados. A equa??o de Einstein foi utilizada para calcular a viscosidade aparente dos fluidos saturados levando em conta o efeito da concentra??o de part?culas salinas em suspens?o. Os experimentos no tanque de mistura tiveram como objetivo o estudo da cin?tica de dissolu??o com o tempo em diferentes condi??es operacionais. Foram preparados fluidos com diferentes concentra??es de goma xantana e diferentes concentra??es iniciais de cloreto de s?dio. Foi analisado o efeito da concentra??o do viscosificante na cin?tica de dissolu??o bem como o efeito do gradiente de concentra??o inicial. Um modelo fenomenol?gico foi utilizado para representar o processo de dissolu??o, o qual prev? as varia??es da concentra??o do fluido, a varia??o da fra??o volum?trica de s?lidos, a varia??o do di?metro m?dio das part?culas e a varia??o da ?rea interfacial de transfer?ncia de massa em fun??o do tempo. Nos estudos de reologia, verificou-se que a adi??o de cloreto de s?dio ao fluido n?o-Newtoniano, nas condi??es estudadas, aumentou a viscosidade aparente da solu??o. O aumento da concentra??o de part?culas suspensas de cloreto de s?dio provocou um aumento na viscosidade aparente das suspens?es. O aumento do tamanho das part?culas suspensas de cloreto de s?dio diminuiu a viscosidade aparente da suspens?o. Testes estat?sticos foram feitos para analisar a relev?ncia estat?stica dos estudos realizados. No estudo da cin?tica, o coeficiente convectivo de transfer?ncia de massa foi estimado e simula??es foram feitas para as demais vari?veis do processo. As estima??es mostraram que a concentra??o de goma xantana no fluido e a concentra??o inicial de cloreto de s?dio no fluido influenciam o coeficiente de transfer?ncia de massa. O erro relativo m?dio simula??es observado para as simula??es foi de 2,2%.

No description available.

L’objectif de ce travail est de comprendre les effets d’un changement de composition des modèles fromagers sur la mobilité, la libération et la perception de molécules de la flaveur (sel, composés d’arôme). Six modèles fromagers aromatisés ont été formulés (3 ratios lipides/protéines (L/P) et 2 teneurs en sel). La microstructure et les propriétés rhéologiques des modèles fromagers ont été caractérisées respectivement par microscopie confocale et par compression uniaxiale. La mobilité des ions sodium a été analysée par RMN 23Na. La cinétique de libération des ions sodium a été suivie dans l’eau, puis dans la salive, en situation de consommation. La libération rétronasale des composés d’arôme a été suivie par nose-space APCI-MS, simultanément au suivi des déglutitions, et de la mastication par électromyographie. Enfin, les propriétés sensorielles des modèles fromagers (intensité salée, arôme, texture) ont été étudiées.Une diminution du ratio L/P et une diminution de la teneur en sel diminuent la taille des gouttelettes lipidiques et augmentent la fermeté. Cela conduit à une diminution de la mobilité des ions sodium, qui se traduit par une diminution de la quantité de sodium libéré dans la salive et une diminution de la perception salée. De plus, le maximum de libération d’arôme est atteint plus tard et la perception aromatique est diminuée. Ces effets peuvent être expliqués par la répartition lipides/protéines observée en microscopie, par une déglutition plus tardive et une plus grande activité masticatoire / The aim of this work is to understand the effects of changes in the composition of model cheeses on mobility, release and perception of flavor molecules (salt, aroma compounds). Six flavoured model cheeses were formulated (3 lipid/protein (L/P) ratios and 2 salt contents). The microstructure and the rheological properties of the model cheeses were characterized respectively by confocal microscopy and by uniaxial compression test. The mobility of sodium ions was analyzed by 23Na NMR. The kinetics of sodium release was followed in water and then in saliva during consumption of the model cheeses. The retronasal release of aroma compounds was followed by nose-space APCI-MS, simultaneously with the study of swallowing and chewing by electromyography. Then, the sensory properties of the model cheeses (saltiness, aroma, texture) were studied.A decrease in the L/P ratio and a decrease in salt content reduce the fat droplet size and increase the hardness. This leads to a decrease in sodium ion mobility, which results in a decrease in sodium release in saliva and a decrease in salty perception. Moreover, the maximum intensity of aroma release is reached later and the aroma perception is decreased. These effects can be explained by the observed lipid/protein distribution in microscopy, by the later swallowing and by the higher chewing activity