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Možnosti využití skelného recyklátu pro přípravu směsných cementů / Possibilities of using recycled glass for the preparation of blended cementsDobrovolný, Petr January 2015 (has links)
This work focuses on the possibility of using recycled glass in the manufacture of blended portland cements. It examines the possibilities to improve pozzolanic properties of recycled glass with new milling processes, the formation of agglomerates material during the course of grinding and their subsequent effect on the hydration process of binders. It is also the optimization of the grinding process with respect to the wear of grinding bodies, grinding energy consumption and maximize the performance of the mill.
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On the kinetics of protein misfolding and aggregationBuell, Alexander Kai January 2011 (has links)
Protein (mis)folding into highly ordered, fibrillar structures, amyloid fibrils, is a hallmark of several, mainly neurodegenerative, disorders. The mechanism of this supra-molecular self-assembly reaction, as well as its relationship to protein folding are not well understood. In particular, the molecular origin of the metastability of the soluble state of proteins with respect to the aggregated states has not been clearly established. In this dissertation, it is demonstrated, that highly accurate kinetic experiments, using a novel biosensing method, can yield fundamental insight into the dynamics of proteins in the region of the free energy landscape corresponding to protein aggregation. First, a section on Method development describes the extension and elaboration of the previously established kinetic assay relying on quartz crystal microbalance measurements for the study of amyloid fibril elongation (Chapter 3). This methodology is then applied in order to study in great detail the origin of the various contributions to the free energy barriers separating the soluble state of a protein from its aggregated state. In particular, the relative importance of residual structure, hydrophobicity (Chapter 4) and electrostatic interactions (Chapter 5) for the total free energy of activation are discussed. In the last part of this thesis (Chapter 6), it is demonstrated that this biosensing method can also be used to study the binding of small molecules to amyloid fibrils, a very useful feature in the framework of the quest for potential inhibitors of amyloid formation. In addition, it is shown that Thioflavin T, to-date the most frequently employed fluorescent label molecule for bulk solution kinetic studies, can in the presence of potential amyloid inhibitor candidates be highly unreliable as a means to quantify the effect of the inhibitor on amyloid formation kinetics. In summary, the work in this thesis contributes to both the fundamental and the applied aspects of the field of protein aggregation.
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The influence of the Ionic Liquid [C14MIM][Cl] on the structural and thermodynamic features of zwitterionic and anionic model membrane / A influência do Líquido Iônico [C14MIM][Cl] nas características estruturais e termodinâmicas de membranas modelos zwiterionicas e ânionicas.Luma Melo de Oliveira 17 March 2017 (has links)
Ionic Liquids (ILs) has been attracting attention, both from academia and industry, given the numerous applications of these systems. ILs are salts, usually composed by an organic ion, and a counterion which could be organic or inorganic, and, interestingly they are found at liquid state at room temperature. Our interest in studying ILs comes from its low toxicity. Some recent studies have shown that the toxicity of the ILs ishigher than believed, in particular for biologically relevant systems. The main goal of this research is to study the influence of the ionic liquid 1-tetradecyl-3-methylimidazolium chloride ([C14MIM][Cl]) with membrane systems. To do so, we made use of different lipids: POPC, Sphingomyelin, Cholesterol, POPG, DPPC, DPPG and DMPC. For each of these systems, the influence of ILs concentration were elucidated by means of a systematic study through different experimental techniques: Small Angle X-ray scattering (SAXS), dynamic light scattering (DLS), fluorescence anisotropy, optical microscopy and z-potential. Since [C14MIM][Cl] has a positive charge on the imidazolium group, the superficial charge of all vesicles increased. For zwitterionic vesicles no significant change in size and melting temperature were noticed. The imidazolium-based ionic liquid diminished the gel-fluid transition temperature for negatively charged lipids. For DPPC:DPPG (1:1), for instance, the transition temperature decreased from 42.50±0.13oC to 25.27±0.33oC and for DPPG from 46.12±0.22 oC to 36.6±0.38 oC. For DPPG, the vesicle hydrodynamic diameter increased from 84±0.1nm to 176±0.1nm, whereas for DPPC:DPPG it increased from 95±0.1nm to 196±0.1nm. The electronic density profile, obtained by SAXS, supported the penetration of the [C14MIM][Cl] into the negative bilayer structure. 15 mol% of [C14MIM][Cl] increased the polar head thickness of DPPC vesicles from 11.1±0.6 Å to 18.0±0.7 Å, without alter significantly the inner region of the membrane.Qualitative results obtained with optical microscopy showed that the IL incorporation destabilize the membrane asymmetry (between the leaflets) leading to the formation of pores (evidenced by optical contrast lost) and the presence of buds. We believe that this work could improve the understanding of the effects of ILs in the presence of biological relevant systems / Os líquidos iônicos (LI) tem atraído grande atenção, tanto da academia quanto da indústria, devido às suas numerosas aplicações. LI são sais, normalmente compostos por um íon orgânico, e um contra-íon que pode ser orgânico ou inorgânico, mas que tem como característica ser encontrado no estado líquido à temperaturas próximas a ambiente. Nosso interesse em estudar LIs vem de sua baixa toxicidade, atribuída a sua baixa volatilidade. Entretanto, alguns estudos recentes mostraram que a toxicidade dos LI é maior do que se acreditava, em particular com sistemas de relevância biológica.O objetivo principal desta dissertação é estudar a influência do líquido iônico 1-tetradecil-3-metilimidazólio cloreto ([C14MIM][Cl]) com sistemas de membrana. Para isso, utilizamos diferentes lipídios, como o POPC, esfingomielina, colesterol, POPG, DPPC,DPPG e o DMPC. Para cada um destes sistemas, a influência da concentração de LI foi elucidada por meio de um estudo sistemático através de diferentes técnicas experimentais, tais como: espalhamento de raio-X a baixos ângulos (SAXS), espalhamento dinâmico de luz (DLS), anisotropia de fluorescência, microscopia óptica e potencial-z. Uma vez que o componente iônico de [C14MIM][Cl] tem uma carga positiva no grupo imidazólio, a carga superficial de todas as vesículas estudadas aqui aumentou. Entretanto, para asvesículas compostas pelos lipídeos zwitteriónicos, não tenha sido observada qualquer alteração significativa no tamanho e na temperatura de transição de fase gel-fluido. O [C14MIM][Cl] altera a organização interna entre as moléculas de lipídio com carga negativa. Consequentemente, à medida que a quantidade de LI aumenta, a temperatura de transição de fase diminui e o tamanho médio das vesículas aumenta. Para o sistema DPPC:DPPG (1:1) a temperatura de transição de fase caiu de 42.50 ± 0.13 oC para 25.27 ± 0.33 oC e para as vesículas de DPPG de 46.12±0.22 oC para 36.6±0.38 oC. Quanto ao diâmetro hidrodinâmico médio, no caso do DPPG este valor aumentou de 84±0.1 nm para 176±0.1 nm, enquanto que para a mistura DPPC:DPPG (1:1) ele passou de 95±0.1nm para 196±0.1nm. Indicando assim que o LI incorpora na bicamada lipídica negativamente carregada. O perfil de densidade eletrônica, obtido por SAXS, confirma a penetração do [C14MIM][Cl] na bicamada lipídica. Diferentemente, para a membrana lipídica zwitteriónica o LI tende a se situar perto da região da cabeça polar sem afetar significativamente a região do interior da bicamada lipídica. Por outro lado, a presença de15 mol% de [C14MIM][Cl] aumenta a espessura da região polar das bicamadas das vesículas de DPPC de ~ 11.1±0.6 Å para ~ 18.0±0.7 Å. Os resultados qualitativos da microscopia óptica mostraram que a incorporação da LI desestabiliza a assimetria da membrana entre as camadas interna e externa, além de sugerir o aparecimento de poros (evidenciado pela perda do contraste ótico das vesículas) e estruturas chamadas de buds. Esperamos que este trabalho melhore a compreensão dos efeitos do LI na presença de organismos biológicos.
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Estimation des propriétés électriques/diélectriques et des performances de séparation d'ions métalliques de membranes d'ultrafiltration et/ou de nanofiltration / Estimate the electrical/dielectric properties and metals ions separation performances of ultrafiltration and/or nanofiltration membranesEfligenir, Anthony 22 October 2015 (has links)
La caractérisation des propriétés électriques et diélectriques des membranes d’UF et de NF constitue une étape essentielle pour la compréhension de leurs performances de filtration. Une nouvelle approche a été développée pour déterminer les propriétés diélectriques d’une membrane de NF par spectroscopie d’impédance. Celle-ci repose sur l’isolement de la couche active du support membranaire et sur l’utilisation de mercure comme matériau conducteur, ce qui nous a permis de prouver que la constante diélectrique de la solution à l’intérieur des nanopores est inférieure à celle de la solution externe. Deux configurations de cellule (fibres immergées dans la solution d’étude ou fibres noyées dans un gel isolant) ont été étudiées pour la réalisation de mesures électrocinétiques tangentielles sur fibres creuses et la solution autour des fibres s’est avérée influencer à la fois le courant d’écoulement et la conductance électrique de la cellule. De plus, la contribution importante du corps poreux des fibres au courant d’écoulement ne permet pas de convertir cette grandeur en potentiel zêta luminal. Les propriétés intéressantes de ces membranes ont finalement été mises à profit pour décontaminer des solutions contenant des ions métalliques. Les performances de dépollution, en termes de rétention des polluants et d’impact écotoxicologique, ont été étudiées sur des solutions synthétiques et un rejet issu de l’industrie du traitement de surface. Bien que les performances de rétention aient été remarquables, la toxicité de l’effluent réel n’a pu être totalement annihilée. Une étude approfondie de la rétention des polluants non métalliques s’avère donc nécessaire. / The characterization of electrical and dielectric properties of UF and NF membranes is an essential step to understand their filtration performance. A new approach has been developed to determine the dielectric properties of a NF membrane by impedance spectroscopy. This is based on the isolation of the membrane active layer and the use of mercury as conductive material, which allowed us to prove that the dielectric constant of the solution inside nanopores is lower than that of the external solution. Two cell configurations (fibers immersed in the solution or fibers embedded in an insulating gel) were investigated for the implementation of tangential electrokinetic measurements with hollow fibers and the solution around the fibers was found to influence both streaming current and cell electrical conductance. Moreover, the important contribution of the fiber porous body to the streaming current does not allow the conversion of the latter to luminal zeta potential. The advantageous properties of these membranes were finally used to decontaminate solutions containing metal ions. Decontamination performances in terms of both pollutant retention and ecotoxicological impact were studied on synthetic solutions and a discharge water from surface treatment industry. Although retention performances were remarkable, the toxicity of the real effluent could not be totally annihilated. A thorough study of the retention of non-metallic contaminants is thus required.
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Studium interakcí biopolymer - tenzid pomocí mikrokalorimetrie a metod rozptylu světla / Microcalorimetric and Light Scattering Methods in the Study of Interactions in Biopolymer - Surfactant SystemŠojdrová, Kamila January 2018 (has links)
Biopolymer surfactant systems have been studied by using different physico chemical methods. As the biopolymer, it was chosen high (1400–1600 kDa), medium (250–450 kDa) and low (8–15 kDa) molecular weight sodium hyaluronate. Two cationic surfactants – cetyltrimethylammonium bromide (CTAB) and carbethopendecinium bromide (Septonex) were selected to provide polyelectrolyte complexes with oppositely charged hyaluronan. The critical aggregation concentration of the surfactant in the system was monitored by dynamic light scattering (Zetasizer Nano ZS). SEC-MALS method was used for the description of the conformation of sodium hyaluronate of different molecular weights and polyelectrolytes complexes hyaluronan surfactant after reaching the aggregation point. Isothermal titration calorimetry (ITC) was used to determine the critical aggregation concentration of the surfactant by monitoring the thermal changes accompanying the aggregation of the system. It was found out that the increasing molecular weight of hyaluronan in these systems decreases the critical aggregation concentrations and conversely.
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Příprava a charakterizace komplexních liposomálních systémů pro distribuci léčiv / Preparation and characterization of complex liposomal for drug delivery systemsSzabová, Jana January 2019 (has links)
This diploma thesis deals with the preparation and characterization of stealth liposomes and their combination with trimethylchitosan (TMC). This complex could find application in the field of inhalation administration. Stealth liposomes were prepared from neutral phophatidylcholine, negatively charged fosfatidic acid and polyethyleneglycol bounded to phosphatidylethanolamine. We have managed to prepare stealth liposomes with suitable properties that should guarantee passive targeting without evocation an immune response, despite the content of the negative component. We also found a suitable method of preparation for stealth liposome–TMC complex, where the change of size and zeta potential confirmed the non–covalent bound between two components despite the content of the polyethyleneglycol.
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Syntéza kvantových teček pro in-vivo zobrazování / Synthesis of quantum dots for in-vivo imagingFerdusová, Helena January 2015 (has links)
The aim of this work was to synthesise water-soluble QDs using different precursors and stabilizers and to determine the toxicity of the synthesized QDs by in vivo imaging. Experiments were performed on water-soluble QDs (MPA-CdTe, MPA-CdTe/ZnS, MSA-CdTe, MSA-CdTe/ZnS, GSH-CdTe, GSH-CdTe/ZnS, TGA-CdTe, TGA-CdTe/ZnS, GSH-ZnSe and GSH-ZnSe/ZnS ) and toxicity was measured. Synthesized QDs were characterized by high intensity (fluorescence spectroscopy), FWHM and zeta potential (ZS Zetasizer) were selected due to their suitability for this task. The toxicity of QDs was determined by the MTT assay on the cell line HEK 293. The experiments show that a core/shell structure is less toxic than a core structure. The results indicate that the toxicity of our synthesized QDs is the lowest for MPA-CdTe (core structure) and MPA-CdTe/ZnS (core/shell structure).
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Metody rozptylu světla a kalorimetrie ve studiu systémů hyaluronan-albumin / Study of hyaluronan-albumin systems using light scattering methods and calorimetrySereda, Alena January 2016 (has links)
This thesis, which is a continuation of the previous Bachelor thesis, is dedicated to the study of polyelectrolyte complexes between hyaluronan (HA) and bovine serum albumin (BSA). Interactions between HA and BSA and a formation of complexes were studied by SEC-MALLS method, where a molar mass, a root mean square (rms) radius, a hydronamic radius and an intrinsic viscosity of particles of the system were defined. Furthermore the interactions were studied by calorimetric measurement ITC, where thermodynamic character of complex formation was determined. Additionally, dynamic and electrophoretic light scattering methods (DLS and ELS) were applied, where hydrodynamic radius and a value of the zeta potential were defined. Also the effect of higher temperature on the character and complex formation was examined by SEC-MALLS and ITC measurements. The interactions were confirmed at any of the used media, but with different efficiency. It was also proved that complexes become smaller in their radii and viscosity with growing BSA concentration. Furthermore it was proved, that the high ionic strength hinders surface charges of HA and BSA molecules and minimizes their mutual interactions. At the higher ionic strength the radii of the complexes, their intrinsic viscosity and zeta potential are increased. The higher temperature has only minimal effect on the formation of the complexes.
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Flottation des particules fines : application aux résidus miniers contenant des minéraux porteurs de terres rares / Fine particles flotation : Application to mine tailings containing rare earth bearing mineralsGeneyton, Anthony 06 September 2019 (has links)
La flottation des particules fines est un challenge technique que l’industrie minière doit relever pour pouvoir exploiter de manière optimale certains types de gisement dont les minerais présentent des textures particulièrement fines. Cette problématique revêt une importance particulière avec la diminution des ressources minérales considérées comme conventionnelles du point de vue de la maille de libération des minéraux d’intérêt. Il existe deux manières d’optimiser les procédés de flottation pour un minerai, la recherche des paramètres de fonctionnement optimaux des équipements de flottation existants et l'élaboration de nouveaux réactifs de flottation. Les travaux des dernières décennies ont mis en évidence qu’en raison de leurs hauts régimes hydrodynamiques favorisant le contact entre les bulles et les particules, les techniques de flottation intensive étaient beaucoup plus adaptées pour le traitement des fines que les dispositifs de flottation mécanique. Cependant, en raison du temps de résidence très court au sein de ces dispositifs de flottation, il est nécessaire que la surface des minéraux d’intérêts soit rendue particulièrement hydrophobe. En ce sens, l’amélioration des performances de flottation, pour les minerais à granularité réduite, par des techniques de flottation intensive requiert l’élaboration de réactifs de flottation plus efficaces et plus sélectifs. L’objet d’étude qui a été choisi est un résidu fin produit à l’issue des différentes étapes nécessaires à l’extraction de l’or et du tellure à partir du minerai de la mine de Kankberg en Suède. Ce résidu à granularité fine possède une faible teneur en terres rares présentes sous la forme de monazite, un minéral de type phosphate. Les travaux de thèse présentés dans ce manuscrit consistaient à développer un réactif permettant d’améliorer l’adsorption d’un collecteur sur la surface de la monazite pour faciliter sa récupération lors de la flottation intensive. Il ressort de ces études que les ions lanthane peuvent améliorer significativement l’adsorption des collecteurs de type carboxylate sur la surface de la monazite et donc améliorer la flottabilité de cette dernière. Les connaissances actuelles concernant les propriétés de surface de la monazite et les mécanismes d’adsorption des collecteurs anioniques sur la surface de ce minéral sont relativement limitées. Il paraissait donc judicieux de contribuer au cours de cette thèse à l’amélioration de ces connaissances. Une étude a été menée pour évaluer l’hydroxylation de surface de la monazite qui est largement considérée dans la littérature comme influençant l’adsorption du collecteur. La manipulation de monazite peut conduire à une exposition aux radiations en raison de la radioactivité émise par la chaîne de désintégration des actinides souvent présents en quantité significative dans le réseau cristallin de la monazite. Au cours de ce projet doctoral, la synthèse de matériaux indurés analogues à la monazite a également été étudiée dans le but de faciliter le déroulement des expérimentations qui nécessitent l’utilisation de monazite. Un protocole de synthèse de poudre de monazite suffisamment indurée pour être agitée a été développé. Des mesures de mobilité électrophorétiques ont par ailleurs montré que les propriétés de surface de ces monazites de synthèse sont identiques à celles d’une monazite naturelle à composition complexe démontrant par ailleurs que la présence de nombreuses substitutions atomiques dans le réseau cristallin de la monazite n’avait pas d’influence sur sa mobilité électrophorétique. / The flotation of fine particles is a technical challenge that the mining industry must address to efficiently exploit certain types of deposit whose ores are finely textured. This issue is of particular importance with the depletion of mineral resources considered as “conventional” with regards to the liberation mesh of minerals of interest. There are two basic approaches to optimise the flotation process for a particular ore, the research for the best working parameters of existing flotation devices and the development of new flotation reagents. The research works in the past decades highlight that, owing to their high hydrodynamic regimes, intensive flotation technologies are more adapted to the treatment of fine particles than conventional mechanical flotation devices. However, due to the short residence time in intensive flotation cells, it is essential that the surface of the minerals of interest has been particularly hydrophobised. In this sense, the improvement of the flotation performance for fine grained ores implies both the use of new flotation technologies and the development of more efficient and more selective flotation reagents. The selected object of studies is a fine grained residue produced after the extraction of gold and tellurium out of the ore from the Kankberg mine which is located in Sweden. This fine material contains low amounts of rare earth elements, in the form of monazite, a phosphate mineral. The thesis works presented in this manuscript consists of developing a reagent that improves the adsorption of the collector on the surface of monazite to facilitate its recovery throughout intensive flotation. The conducted studies emphasise that lanthanum ions significantly promote the adsorption of carboxylate type collectors on the monazite surface thereby increasing the floatability of this mineral. Current knowledge regarding the surface properties of monazite and the mechanism of anionic collectors adsorption on the monazite surface are relatively limited. Therefore, it seems wise to contribute to improving this knowledge during this thesis. A study was carried out to assess the hydroxylation of the monazite surface which is largely considered in the literature as a phenomenon influencing the collector adsorption. The handling of monazite may cause radiation exposure because of the radioactive decay chains of the actinide elements naturally present in the monazite crystal lattice. During this thesis, the synthesis of indurated monazite analogue materials was also investigated to facilitate the conduct of experiments. A protocol of synthesis of monazite powder sufficiently indurated to be mechanically stirred has been developed. Electrophoretic mobility measurements highlight that the surface properties of the synthetic monazite materials were similar to those of natural monazite with complex chemistry showing, in addition, that the presence of several atom substitutions in the monazite crystal lattice has no influence on its electrophoretic mobility.
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Mechanisms of polymer adsorption in nanoparticle stabilization for poorly water soluble compoundsWiser, Lauren Sample 01 January 2011 (has links)
In this dissertation, the mechanisms of nanosuspension stabilization via polymer adsorption on nanoparticle surface were investigated. As the electrokinetic behavior and colloidal stability depend on the surface characteristics, altering the surface adsorbed polymers affords the different surface properties of nanoparticles and leads to the insight on the mechanism of nanoparticle stabilization. Drug nanosuspensions were prepared by wet milling of drug with water as medium and polymers as stabilizers. Block copolymers were evaluated based on varying the hydrophobic and hydrophilic amounts, polymer concentration, and polymer affinity differences onto the nanoparticle surface. Specifically, block copolymers of ethylene oxide (EO) and propylene oxide (PO) with different EO chain lengths were used to modify the nanoparticle surface and investigate the mechanisms of stabilization by varying the ratio of hydrophobic (PO) and hydrophilic (EO) units. It was hypothesized that the PO chain of block copolymers adsorb at the solid-solution interface and the EO chain provides steric hindrance preventing aggregation. Block copolymer adsorption layer thicknesses were experimentally determined with adsorption layer thicknesses increasing from 4.7 to 9.5 nm as the number of EO increase from 26 to 133 monomer units. Nanoparticle aggregation occurred with insufficient polymer monolayer coverage and electrokinetic zeta potential greater than -20 mV. The amount of block copolymers on the surface of nanoparticles was quantified and the affinity of polymer adsorption increased as the copolymer hydrophobic units increased. The amount adsorbed and affinity provides a qualitative ranking of the affinities between a specific polymer and nanoparticle substrate to provide a method in determining the mechanism of stabilization, where specific functional groups for adsorption could be selected for maximum nanoparticle stability. A molecular modeling was conducted to visualize and support the mathematical model and the proposed mechanism of block copolymer adsorption onto a nanoparticle surface. The time lapse molecular modeling of a block copolymer in an aqueous media showed the hydrophobic units adsorbing onto the nanoparticle surface with the hydrophilic units projecting into the aqueous media. For the first time in pharmaceutical research, a systematic series of studies were conducted to elucidate the mechanisms of adsorption with both surface charge and polymer affinity analyses. A series of studies evaluating the adsorption properties polymer stabilizers provided useful information on how a block copolymer comprised of both hydrophilic and hydrophobic domains adsorbs onto an active pharmaceutical ingredient. A systematic set of experimental techniques were presented with novel analysis tools and predictors to construct stable nanoparticle formulations.
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