Highly cross-linked monoliths prepared from single cross-linking monomers were found to increase surface area and stability. Therefore, seven cross-linking monomers, i.e., 1,3-butanediol dimethacrylate (1,3-BDDMA), 1,4-butanediol dimethacrylate (1,4-BDDMA), neopentyl glycol dimethacrylate (NPGDMA), 1,5-pentanediol dimethacrylate (1,5-PDDMA), 1,6-hexanediol dimethacrylate (1,6-HDDMA), 1,10-decanediol dimethacrylate (1,10-DDDMA), and 1,12-dodecanediol dimethacrylate (1,12-DoDDMA), were used to synthesize highly cross-linked monolithic columns in 75-µm i.d. capillaries by one-step UV-initiated polymerization using dodecanol and methanol as porogens for reversed-phase liquid chromatography (RPLC) of small molecules. Selection of porogen type and concentration was investigated in detail. Isocratic elution of alkylbenzenes at a flow rate of 300 nL/min was conducted for all of the monoliths. Gradient elution of alkylbenzenes and alkylparabens provided high resolution separations. Several of the monoliths demonstrated column efficiencies in excess of 50,000 plates/m. Monoliths with longer alkyl-bridging chains showed very little shrinking or swelling in solvents of different polarities. In addition, highly cross-linked monolithic capillary columns poly(1,6-HDDMA), poly(cyclohexanediol dimethacrylate) [poly(CHDDMA)] and poly(1,4-phenylene diacrylate) [poly(PHDA)], were synthesized and compared for RPLC of small molecules. Isocratic elution of alkylbenzenes was performed using 1,6-HDDMA and CHDDMA monolithic columns. Gradient elution of alkylbenzenes using all three monolithic columns showed good separations. Monolithic columns formed from 1,6-HDDMA, which had a linear alkyl-bridging chain structure, exhibited the highest column efficiencies (86,000 plates/m). Optimized columns showed high permeability and high run-to-run and column-to-column reproducibilities. Monoliths prepared from controlled/living polymerization was demonstrated exhibiting narrower molecular weight distribution and more homogeneous cross-linked structures due to the reversible character of this polymerization method. Thus, monolithic columns were developed from three cross-linking monomers, i.e., 1, 12-DoDDMA, trimethylolpropane trimethacrylate (TMPTMA) and pentaerythritol tetraacrylate (PETA) using organotellurium-mediated living radical polymerization (TERP) in 150-µm i.d. capillaries for RPLC of small molecules. Selection of the polymerization conditions for the 1,12-DoDDMA monolirh was investigated in detail. Isocratic elution of alkylbenzenes was achieved with good efficiency (47,700 to 64,200 plates/m for uracil) using all monolithic columns prepared using TERP.

Nanoparticles have important applications in ceramics, metal catalysts, semiconductors etc. They are normally required to be of small size (~ nm) and monodisperse. The aim of the present work is to model the formation of nanoparticles, obtained by precipitation in reverse micellar microreactors. These are dispersions of tiny water drops in a surfactant laden oil medium. Two systems were investigated: (i) Reverse micelles, having nanometer sized spherical water droplets in the micellar core and (ii) Water-in-oil emulsions, having micron-sized aqueous drops. Two modes of precipitation, namely, gas-liquid (g-1) and liquid-liquid (1-1) were studied. In each case, the models could predict the number, average size and size distribution of the particles reported in literature. Two groups have obtained widely divergent number and size of CaCO3 nanoparticles, formed by g-1 precipitation in reverse micelles. These particles are used as a fine suspension in lube-oil additives, where they serve to neutralize acid produced during combustion in engines. Kandori et al. (J. Colloid Interface Sci, 122,1988, 78) obtained particles of about 100 nm size, by passing CO2 through a reverse micellar solution, containing dissolved Ca(OH)2 in the micellar core. Roman et al. (J. Colloid Interface Sci., 144,1991, 324), instead of using lime solution; added micron-sized solid lime particles in the oil and generated the reverse micelles by in situ reaction. This is a commercial process known as overbasing. It led to a higher amount of lime in the micelles as well as unreacted lime particles in oil, at the beginning of the experiment Upon passing CO2, they got particles of only 6 nm in size, compared to 100 nm reported by Kandori et al.. Furthermore, while Kandori et al. found that one particle formed from 108 micelles, Roman et al. got one particle out of only ten micelles. We have modelled the two processes in a common framework to explain the reported disparity in particle characteristics. A time scale analysis of CO2 mass transfer, reaction, collision-fusion of micelles, nucleation, and growth of particles was carried out It showed that, in the experiments of Kandori et al., the rate limiting steps are nucleation and fusion. The analysis also indicates that the contents of a particular micelle are well mixed and reaction of lime and incoming CO2 can be treated as instantaneous. In the process of Kandori et al., the amount of lime taken initially being very small, the average number of product molecules in a micelle is well below one. Rapid Brownian coalescence and exchange of micellar contents leads to Poisson distribution of CaCO3(l) molecules formed by reaction. The low occupancy therefore suggests that most of the micelles are empty. Nucleation in a particular micelle is much slow and occurs when it has a critical number of molecules. Thus only very few micelles can nucleate. Comparison of nucleation and growth time scales - both intrinsic growth in a micelle and growth during fusion of nucleated and non-nucleated micelles - show that growth is much faster than both nucleation and collision. Hence a micelle can have only one nucleus, with subsequent growth during collisions. A population balance equation (PBE) is written involving the above steps. Solution of the moments of the distribution yields the number of CaCO3 particles, its size, coefficient of variance (COV) etc. The model not only predicts the ratio of number of micelles to particles, obtained experimentally as 108, but also captures the maxima in this quantity with increasing micellar size. The increase in average particle size with micellar size is also predicted well. The process of of Roman et ai, in addition, involves the time scale of solubilization of solid lime into micelles. Its comparison with other time scales demarcates their experiments into two distinct phases. Phase I consists of reaction of lime initially present in micelles. Time scale analysis also suggests that, as the lime content in the micelles is large, a high degree of supersaturation is rapidly generated. This results in a burst of nuclei. The other conclusions, like, well-mixed micelle, Poisson distribution of CaCO3(l) molecules, instantaneous growth and mono-nucleated micelles are found to hold good. Once the pre-existing lime is finished, relative time scales indicate that, further precipitation is controlled entirely by fresh solubilization of lime. This marks the beginning of phase II. However, solubilization being the slowest step, CaCO3(l) in micelles never builds up for any further nucleation. Phase II thus consists of pure growth of the particles formed in phase I. On developing more general PBEs and with solution of resulting moment equations - written separately for the two phases - the experimental data on number of particles and temporal evolution to the final particle size of 6 nm could be predicted very well. The model also captures the qualitative trend in COV of particle radius with time. Thus within the same framework we could successfully predict both the results, differing by seven orders of magnitude. The above analysis indicates that relative rates of nucleation, fusion-growth and mass transfer of gas controls the carbonation process. We further simplify the process and obtain an analytical solution in the limit of instantaneous mass transfer. The solution gives close first estimates for both the experiments and also indicates the smallest panicle size that could be obtained for a given experimental condition. In contrast to g-1 mode, precipitation in 1-1 mode - using two reverse micellar solutions having two reactants- occurs only on coalescence of two micelles. To obviate the solution of multivariate PBEs, we have developed a general Monte Carlo (MC) simulation scheme for nanoparticle formation, using the interval of quiescence technique (IQ). Starting with a fixed number of micelles, we conduct each coalescence-redispersion and nucleation events in this population, in the ratio of their relative frequencies. Our simulation code is much more general and realistic than the scheme of Li and Park (Langmuir, 15,1999, 952). Poisson distribution with realistic micellar occupancies of reactants, binomial redispersion of solutes after fission, a nucleation rate with critical number of molecules and Brownian collision-fusion rates were used. These considerations are based on our earlier findings in g-1 precipitation and those known in the literature too. The simulation of Li and Park then becomes a special case of our code. Our simulation code was then used to predict experimental data on two systems. The results of Lianos and Thomas (Chem. Phys. Lett. 125, 1986, 299 and /. Colloid Interface 5c/., 117, 1987, 505), on number of molecules per CdS particle, as a function of micelle size and reactant concentrations have been predicted very well. For the Fe(OH)3 nanoparticles, our simulation provides a better prediction of the experimental particle size range, than that of Li and Park. Finally, 1-1 precipitation on mixing two emulsions, having respectively the two reactants, has been simulated. Here, large reactant amount leads to multiple nucleation in a single drop and renders growth rate to be finite. This requires solving a PBE for particle population in each drop. Moreover, emulsions have a drop size distribution due to independent coalescence and breakage. The IQ technique was used for handling these events. Thus a composite model of PBE and MC for a drop population was developed. Simulation of particle size distribution in MgCO3 precipitation shows that nearly monodisperse nanoparticles can be produced in emulsions. Furthermore, average particle size can be controlled by changing reactant concentration in a drop. The findings of the thesis have provided new issues to be addressed in modelling nanoparticle formation. It points out the importance of finding models for coalescence efficiency and critical nuclear size in micelles. Extension of our model and simulation to precipitation in other organized surfactant assemblies can be done by starting from appropriate time scale analysis.

Volvo Cars är ett välkänt företag som säljer bilar över hela världen. Idag skickar Volvo Cars sin kylvätska till leverantörer för analys. Processen är komplicerad och tar mycket tid. Det finns ett intresse hos Volvo Cars att själva kunna analysera kylvätskan. För att kunna göra detta krävs det att en metod som de kan använda för att analysera kylvätskan utvecklas. Examensarbetet syftar till att utveckla en metod som gör det möjligt att analysera koncentrationen av organiska syror i Volvos kylvätska. Analysen ska göras med hjälp av en High Performance Liquid Chromatography - HPLC. De organiska syrorna är inhibitorer som skyddar material i motorn från korrosion när det kommer i kontakt med kylvätskan. Metoden utvecklas i flera steg, det är viktigt att veta hur olika organiska syror kan analyseras med en HPLC. HPLC-analyser är mycket beroende av de intrumentella inställningarna. Inställningarna som ändrar när metoden utvecklas är pH, typ av kolonn, våglängd på detektorn, flödeshastighet i kolonnen, injektionsvolymen, sammansättning av eluent (lösningsmedel) och analystid. Kalibreringskurvor konstrueras för att sedan kunna användas i fortsatta studier. Tre av fem organiska syror som skulle analyseras var möjliga att analysera med två olika metoder. Den enda skillnaden mellan metoderna var våglängden på detektorn. En av de organiska syrorna hade en mer linjär kalibreringskurva vid en högre våglängd. / Volvo Cars is a well-known company and they are selling their cars all over the world. Today, Volvo Cars send their engine coolant to the supplier of engine coolant for analysis. This process is complicated and takes a lot of time. It is in the interest of Volvo Cars to be able to analyze the engine coolant themselves. In order to do that, a method where they can analyze the engine coolant must be developed. This exam work aim to develop a method where it is possible to analyze the concentration of organic acids in Volvo´s engine coolant with a High Performance Liquid Chromatography - HPLC. The organic acids are inhibitors that protect the materials in the engine from corrosion when in contact with the engine coolant. The method is developed in several steps. First it is important to know how different organic acids could be analyzed with an HPLC. HPLC-analysis is very dependent of the instrumental parameters. The parameters you change when developing a method are pH, kind of column, wavelength of the detector, kind of detector, flow rate in the column, injections volume, composition of the eluent (solvent) and, analysis time. Calibration curves are created and could be used as a reference in further analysis. Three of the five organic acids that were supposed to be analyzed were possible to analyze. Three organic acids were analyzed with one method and the two remaining organic acids with another method. The only difference between the methods is the wavelengths of the detector.

La dynamique des plasmas de fusion par confinement magnétique dans la configuration Reversed Field Pinch (RFP) est ´étudiée en utilisant la description magnétohydrodynamique (MHD) incompressible. Une méthode pseudo-spectrale et une technique de pénalisation en volume sont utilisées pour résoudre le système d’équations dans un cylindre. Les simulations numériques montrent que la pression joue un rôle important dans la dynamique des RFP et ne peut pas être négligée. Ainsi, ß n’est plus le paramètre principal pour décrire la dynamique des RFPs mais plutôt ß’ ∇, un nouveau paramètre qui équivaut le rapport du module de gradient de pression et le module de la force de Lorentz. A un autre niveau, l’effet du changement de la section poloïdale du RFP sur la dynamique est étudié. Les simulations des écoulements RFP ayant le même nombre de Lundquist et des sections différentes (circulaire et elliptique), montrent une grande différence dans les spectres et la diffusion turbulente radiale. Finalement, les écoulements RFP sont utilisés pour étudier l’effet dynamo. Les résultats obtenus montrent que les écoulements RFP sont capables d’amplifier un champ magnétique passif qui aura une tendance à être plus non-linéaire que le champ magnétique du RFP dans les régimes turbulents. / The dynamics of magnetic fusion plasmas in the Reversed Field Pinch (RFP) configuration are studied using an incompressible magnetohydrodynamics (MHD) description. A pseudospectral method combined with a volume penalization method are used to resolve the governing equations in a straight cylinder. Numerical simulations show that the pressure effects on the RFP dynamics cannot be neglected, and thus the _ parameter is not adequate to characterize the importance of pressure in the dynamics. A new parameter, _0r , which is the ratio of the pressure gradient’s magnitude to the Lorentz force’s magnitude, is proposed to be the proper parameter to describe the RFP dynamics. Another investigated influence on the RFP dynamics is the shaping of the poloidal cross-section. Simulations of flows with the same Lundquist number and different cross-sections (circular and elliptic) show a clear change in the spectral behaviour, as well as in the radial turbulent diffusion. Finally, the RFP flows are used to study the dynamo effect. Numerical results show that RFP flows are capable of amplifying a seed magnetic field, which will have tendency to be more nonlinear than the RFP magnetic field in the turbulent regime.

The Supercritical Fluid Extraction (SFE) technique was used to fractionate Suwannee River reference fulvic acid (FA). The fractions were characterized by gas chromatography (GC) and reversed-phase high performance liquid chromatography (RP-HPLC). A SFE fractionation method was developed using stepwise gradient of supercritical CO₂ and methanol. Three FA fractions were separated. The average mass recovery was 102% with the coefficient of variation of 2.8%. The fractionation dynamics and the difference in the ratios of UV absorption to fluorescence emission indicate the real fractionation of the FA. The HPLC chromatographic peak patterns and the spectra of the corresponding peaks were almost indistinguishable. The overall results of this research support the argument that FA exhibits polymer-like molecular structure.

The thesis is focused on application of ion chromatography in pharmaceutical analyses of organic ions. Ion chromatography is increasingly used in the field of pharmaceutical analysis. This includes the analysis of impurities and metabolites. In the first part of this thesis, ion chromatography is compared with common separation techniques used in pharmacy, such as gas chromatography and high performance liquid chromatography. In the second part development and validation of methods of ion chromatography for purity evaluation and quality control of active pharmaceutical substances Rivastigmine hemitartrate and Pramipexole hydrochloride were carried out. Key words: ion chromatography, reversed-phase chromatography, ion-pair chromatography, ion-exclusion chromatography, ion-exchange chromatography, GC, HPLC

Aim: to develop and understand which are the elements that influence the conventional and reversed knowledge transfer, how they influence it and the benefits of transferring knowledge within a multinational corporation. Methods: qualitative research strategy, inductive approach, and single case study design. Ten semi-structured interviews were conducted face-to-face and though video-calls. Four interviewees belong to Italian headquarters, three to the Canadian subsidiary and three to the US subsidiary. Results and conclusions: the research identifies culture, relationship HQ-subsidiary, geographical distance, expatriates, relationship between employees, language difference, trust, transparency, motivation, and technology as the elements influencing conventional and reversed knowledge transfer; the influences these elements exercise on them, and the benefits of knowledge transfer flows. Suggestions for further research: to replicate the qualitative study with a multi-case study design; to develop a deeper understanding on the relationship between the elements; and to deeper understand how knowledge transfer benefits can influence the MNC’s overall performance and subsidiaries’ performance. Contribution of the thesis: it contributes with in-depth understanding of the elements influencing conventional and reversed knowledge transfer, their benefits and a theoretical framework; highlights the importance of knowledge transfer for social development; and it provides an understanding of the benefits of knowledge transfer to achieve competitive advantage.

In the present work, Current Reversal Equilibrium Configurations (CRECs) in the context of Magnetohydrodinamic (MHD) equilibrium are considered. The hamiltonian nature of the magnetic field lines is used to introduce the concept of magnetic surfaces and their relation to the Grad-Shafranov (G-S) equation. From a geometrical perspective and the Maxwell equations, it is shown that current reversal configurations in two-dimensional equilibrium do not generate the usual nested topology of the equilibrium magnetic surfaces. The concept of intersecting critical curves is introduced to describe the CRECs and recently published equilibria are shown to be compatible with such description. The equilibrium with a single magnetic island is constructed analytically, through a local successive approximations method, valid for any choice of the source functions of the G-S equation. From the local solution, an estimate of the island width in terms of simple quantities is deduced and verified to a good accuracy with recently published CRECs; the accuracy of this simple model suggests the existence of strong topological constraints in the formation of the equilibria. Lastly, an instability mechanism is conjectured to explain the lack of conclusive experimental evidence of reversed currents, in favor of the current clamp hypothesis. / No presente trabalho, as configurações de equilíbrio com corrente reversa (CRECs), são consideradas no contexto de Equilíbrio Magnetoidrodinâmico. A natureza hamiltoniana das linhas de campo magnético é usada para introduzir o conceito de superfícies magnéticas, e sua relação com a equação de Grad-Shafranov (G-S). Desde uma perspectiva geométrica e usando as equações de Maxwell, é demonstrado que as configurações de corrente reversa em equilíbrios bidimensionais não é compativel com as topologias aninhadas usuais para as superfícies magnéticas de equilíbrio. O conceito de curvas críticas é introduzido para descrever as CRECs e é observado que os equilíbrios recentemente publicados satisfazem esta descrição. O equilíbrio com uma única ilha magnética é construído analiticamente, por meio de aproximações sucessivas locais, este é válido para qualquer escolha das funções arbitrárias da equação G-S. A partir da solução local, se desenvolve uma estimativa do tamanho da ilha magnética em termos de quantidades simples. Esta estimativa concorda bem com as CRECs da literatura recente, sugerindo pela simplicidade do modelo, que existem fortes restrições topológicas no estabelecimento do equilíbrio. Finalmente, na forma de conjectura, introduzimos um mecanismo para instabilidades que tenta dar conta da falta de evidência experimental conclusiva em relação às CRECs em favor da hipótese de corrente unidirecional (current clamp).

Capsaicinoids are a class of compounds responsible for the "heat" of hot peppers. Capsaicin and dihydrocapsaicin have the highest burning effect. The aim of this work is to separate and quantify the two major capsaicinoids in fruits harvested at different stages of development and at different seasons. Simple and rapid HPLC method involves 73:27% methanol water mobile phase with C18 stationary phase and UV-Vis detector set at 210 nm. The method showed good reproducibility with 1.74% - 4.72% relative standard deviations, a linear response within 0.65–45.5 and 0.25-17.5 μg/mL for capsaicin and dihydrocapsaicin, respectively. The method achieved average recovery of 106% for capsaicin and 102% dihydrocapsaicin. Determination of capsaicinoids in four naturally grown chili and commercial source habanero were analyzed. The amount in the sample ranged from 1184-8156 μg/g for capsaicin and 430-3299 μg/g for dihydrocapsaicin.

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