No description available.

Les tensioactifs poly- et perfluoroalkylés (PFAS) sont des composés d’origine anthropique produits à partir des années 1950 et qui sont désormais considérés comme des polluants ubiquistes. La première partie de ce travail a consisté à optimiser et valider des procédures pour l’analyse ultra-trace des PFAS. Ces méthodes ont ensuite été utilisées afin d’apporter de nouveaux éléments de réponse sur l’occurrence et la dynamique des PFAS dans les environnements aquatiques. Une attention particulière a été accordée aux valeurs censurées (<LD). Dans les eaux de surface et les sédiments, à l’échelle nationale, le perfluorooctane sulfonate (PFOS) s’est avéré prédominant parmi les acides perfluoroalkylés (PFAA) considérés ; la fraction organique du sédiment est apparue un facteur de contrôle clé des teneurs sédimentaires. L’utilisation des cartes auto-organisatrices de Kohonen a facilité la synthèse des résultats et les comparaisons entre sites. A une échelle plus locale, ces travaux ont permis de cartographier la contamination sédimentaire d’un estuaire macrotidal et d’étudier les facteurs de contrôle de leur distribution. La dynamique spatio-temporelle des PFAS et leur transfert aux premiers maillons trophiques ont été évalués en milieu fluvial urbain (la Seine) et en milieu estuarien (la Gironde). La détermination des facteurs d’amplification trophique en estuaire de Gironde confirme le caractère bioamplifiable du PFOS et de certains PFAA à longue chaîne. Le dernier axe de ces travaux concernait la recherche de PFAS d’intérêt émergent zwittérioniques et cationiques ; des résultats préliminaires semblent dissiper les inquiétudes concernant leur potentiel de bioaccumulation. / Poly- and perfluoroalkyl surfactants (PFAS) are anthropogenic compounds that have been used sincethe 1950s in a variety of applications and that have emerged as ubiquitously distributed contaminants.The first aim of this work was to optimize and validate analytical procedures for the trace-leveldetermination of PFAS. These methods were then applied to various sets of environmental samples,providing new elements to document the occurrence and environmental fate of PFAS in aquaticecosystems. In terms of statistical analyses, a special care has been devoted to incorporate nondetects(data <LOD). In French surface waters and sediments, perfluorooctane sulfonate (PFOS) wasthe prevailing perfluoroalkylated acid (PFAA); sediment organic carbon fraction was a key controllingfactor of PFAS sedimentary levels. Kohonen self-organizing maps were used to highlight similaritiesand differences between sites, providing evidence for distinctive features, sometimes at watershedscale. A mapping of PFAS in sediments was established in a macrotidal estuary, along with theirpartitioning behavior in the water column. The spatio-temporal dynamics of PFAS and transfer to thefirst trophic levels were investigated in an urban freshwater hydrosystem (the Seine River) and in anestuarine environment (Gironde estuary). In the Gironde estuary, trophic magnification factors (TMF)were significantly >1 for PFOS and several long-chain PFAA, providing new evidence for theirbiomagnification. The last theme addressed in this work was the analysis of newly-identified cationicand zwitterionic PFAS ; preliminary evidence seem to dispel concerns about the bioaccumulationpotential of the latter.

In this diploma thesis, the interactions between polyelectrolyte and surfactant at low and also at high concentration were studied. There was used pyrene as fluorescent probe during the fluorescence spectroscopy measurement, a cationic surfactant cetyltrimethylammonium bromide and as a main polyelectolyte has been chosen sodium polystyrene sulfonate at 1 MDa molecular size. In the medium containing 0.15 M NaCl we could observed a creation of the complexes – precipitates in the surrounding of CMC concentration and behind of this concentration. In the mixtures containing sodium polystyrene sulfonate and hyaluronan together, there was stronger tend to keep aggregation properties of sodium polystyrene sulfonate during difference concentration ratios. Beyond CMC concentration, hyaluronan starts to influence the aggregation properties of the system as well.

No description available.

In this thesis, the effect of surfactants (Bi /Sb) on GaAs(111) is explored, particularly in regards to modifying the surface morphology and growth kinetics. Both molecular beam epitaxy (MBE) and metal-organic chemical vapour deposition (MOCVD) techniques are discussed in this context. InAs/GaAs(111) quantum dots (QDs) have been promoted as leading candidates for efficient entangled photon sources, owing to their high degree of symmetry (c_3v). Unfortunately, GaAs(111) suffers from a defect-ridden homoepitaxial buffer layer, and the InAs/GaAs(111) material system does not natively support Stranski{Krastanov InAs QD growth. Surfactants have been identified as effective tools to alter grown surface morphologies and growth modes, potentially overcoming these obstacles, but have yet to be studied in detail in this context. For MBE, it is shown that Bi acts as a surfactant when employed in GaAs(111) homoepitaxy, and eliminates defects/hillocks, yielding atomically-smooth surfaces with step-flow growth, and RMS roughness values of 0.13 nm. The effect is more pronounced as the Bi flux increases, and Bi is suggested to be increasing adatom diffusion. A novel reflection high energy electron diffraction (RHEED)-based experiment was also designed and performed to measure the desorption activation energy (U_Des) of Bi on GaAs(111), yielding U_Des = 1.74 ± 0.38 eV. GaAs(111) homoepitaxy was also investigated using MOCVD, with GaAs(111)B exhibiting RMS roughness values of 0.09 nm. Sb is shown to provoke a morphological transition from plastically-relaxed 2D to 3D growth for InAs/GaAs(111)B, showing promise in its ability to induce QDs. Finally, simulations for GaAs-based quantum well (QW) photoluminescence were conducted, and such QWs are shown to potentially produce very sharp linewidths of 3.9 meV. These results enhance understanding of Bi surfactant behaviour on GaAs(111) and can open up its use in many technological applications, paving the way for the realization of high efficiency/viable QD entangled photon sources. / Thesis / Master of Applied Science (MASc)

No description available.

[pt] O uso de espumas de CO2 em aplicações de recuperação avançada de petróleo (EOR) requer a formação de espumas estáveis sob condições adversas de reservatório, como salmouras contendo cátions bivalentes, alta temperatura e pressão, e uma ampla faixa de pH. Nesse contexto, os surfactantes responsivos ao pH que se comportam como surfactantes não-iônicos em meio básico (ausência de CO2), e são convertidos em espécies catiônicas em condições ácidas (presença de CO2), têm se mostrado uma alternativa adequada para formulações espumantes usadas em métodos de EOR baseados em injeção de CO2. O bis-(2-hidroxietil) cocoalquilamina (C12) se destaca como um surfactante responsivo ao pH (pKa = 6,4) promissor, com potencial para estas aplicações. Contudo, há poucos trabalhos sobre as propriedades das espumas de C12 em diferentes condições de pH, principalmente quando o surfactante se encontra na forma não-iônica. O objetivo deste trabalho foi estudar o comportamento deste surfactante em misturas, visando potencializar suas propriedades espumantes através de efeitos de sinergia na interface. Para isso foram estudadas diferentes propriedades do C12, como comportamento de fases, propriedades interfaciais e comportamentos das espumas, tanto em formulações individuais quanto em misturas com outros surfactantes. Estes dados foram correlacionados com o comportamento do C12 em diferentes condições (pH, temperatura, pressão, e misturas de diferentes composições). Foi observado que em condições básicas ocorre separação de fases, enquanto a espumabilidade e a estabilidade das espumas de C12 no estado catiônico (pH menor que pKa) foram superiores, comparado ao estado não-iônico (pH maior que pKa). Para as misturas de C12 com outros surfactantes (alfa-olefina sulfonato de sódio, AOS; alquilamina etoxilada, TFA20; e cocamidopropil hidroxisultaína, CAHS), as formulações contendo CAHS promoveram uma melhora da solubilidade do C12 em pH alcalinos, estendendo sua aplicabilidade, e foram as únicas a exibir uma sinergia significativa em relação à redução da tensão superficial e à estabilização da espuma. A sinergia interfacial entre C12 e CAHS foi confirmada pelo valor negativo do parâmetro de interação. O efeito sinérgico na estabilidade da espuma também foi observado em condições de alta pressão (100 bar) e alta temperatura (65 graus C), evidenciado pela diminuição da taxa de crescimento de bolhas obtida com a mistura C12:CAHS (1:2) em relação aos componentes individuais, o qual indica uma redução dos fenômenos de coalescência e envelhecimento de Ostwald. Os resultados obtidos neste estudo, mostraram o potencial do uso de misturas sinérgicas com surfactantes para ajustar a sua solubilidade e as propriedades das espumas de surfactantes responsivos ao pH, para um melhor desempenho dos métodos de EOR baseados no uso de espuma sob condições de alta pressão e alta temperatura. / [en] The use of CO2-foams in enhanced oil recovery (EOR) applications requires the formation of stable foams under harsh reservoir conditions, such as brines containing divalent cations, high temperature and pressure and a wide pH range. In this context, pH-responsive surfactants that behave as nonionic surfactants in a basic medium (absence of CO2), and are converted to cationic species under acidic conditions (presence of CO2), have been shown to be a suitable alternative for foaming formulations used in CO2-based EOR methods. The bis-(2-hydroxyethyl) cocoalkylamine (C12) has been reported as a promising pH-responsive surfactant (pKa = 6.4), with great potential for this type of applications. However, there is limited work on the properties of C12 foams under different pH conditions, especially in the nonionic state of the surfactant. This work aimed to study the behavior of this surfactant in mixtures, aiming to improve its foaming properties through synergy effects at the interface. For this, different properties of C12 were studied, such as phase behavior, interfacial properties, and foam behavior, in individual formulations and in mixtures with other surfactants. These data were correlated with the individual behavior of C12 under different conditions (pH, temperature, pressure, mixtures of different compositions). It was observed that under basic conditions phase separation occurs, while the foamability and stability of C12 foams in the cationic state (pH less than pKa) were higher compared to the nonionic state (pH bigger then pKa). For mixtures of C12 with other surfactants (sodium olefin sulfonate, AOS; ethoxylated alkylamine, TFA20; and cocamidopropyl hydroxysultaine, CAHS), formulations containing CAHS promoted an improvement in the solubility of C12 at alkaline pH, extending its applicability, and were the only ones to exhibit significant synergy in terms of surface tension reduction and foam stabilization. The interfacial synergy between C12 and CAHS was confirmed by the negative value of the interaction parameter. The synergistic effect on foam stability was also observed under high pressure (100 bar) and high temperature (65 degrees C) conditions, evidenced by the decrease in the bubble growth rate obtained with the C12:CAHS mixture (1:2) in relation to the individual components, which indicates a reduction of the Ostwald ripening and coalescence. The results obtained in this study showed the potential use of synergistic mixtures of surfactants to adjust the solubility and properties of foams with pH-responsive surfactants for better performance in foam-based EOR methods, under high pressure and high temperature conditions.

No description available.

No description available.

Nanomaterial produceras och används alltmer i tekniska lösningar för att förbättra t.ex. materialegenskaper. Eftersom ett materials egenskaper förändras när det är i nanoskala så påverkas även dess toxikologiska egenskaper. För närvarande finns det ett flertal rapporter om oavsiktligt bildande av metalliska nanopartiklar, Me NPs, vid byggarbetsplatser, vilket riskerar att byggarbetarna exponeras för att andas in dessa partiklar.  På grund av nanomaterialens storleksberoende egenskaper så är inte dagens toxikologiska utvärderingsmetoder sällan anpassade för dessa typer av material. Att undersöka växelverkan mellan Me NPs och pulmonella biomolekyler och utveckla metoder för analys därför av hög prioritet.  I detta examensarbete har en metod för upplösning av det pulmonellt ytaktiva ämnet fosfolipid 1,2-dipalmitoylfosfatidylkolin, DPPC, baserat på sonikering i vattenbad testats och utvärderats. Den simulerade lungvätskan Gambles lösning har testats och utvärderats som en möjlig lösning för att studera växelverkan mellan DPPC och Co NPs. Växelverkan mellan dess komponenter och Co NPs har studerats med hjälp av PCCS, NTA samt ATR-FTIR. Då examensarbetet genomfördes under den pågående Covid-19 pandemin har anpassningar i det experimentella arbetet gjorts med hänsyn till det rådande läget. PCCS visade att vid upplösning av DPPC i lösningen så minskade sonikering omfattningen av sedimentationen och den resulterande storleken på liposomerna låg inom intervallet mellan 50 och 70 nm i ultrarent vatten och mellan 30 och 40 nm i Gamble’s lösning. Skillnaden i liposomstorlek tros bero av växelverkan mellan komponenterna i Gamble’s lösning och DPPC, vilket även observerades med FTIR och överensstämmande med litteraturen. Den relativa skillnaden i liposomstorlek i de olika lösningarna observerades också med NTA, men experimentella problem kan ha påverkat resultaten. Gamble’s lösning hade en inverkan på Co NPs i lösningen, bland annat genom att uppmätta partikelkoncentrationer bestämde med hjälp av PCCS och NTA var mindre än hälften av motsvarande koncentration initialt i ultrarent vatten (vid 0 h). En trolig förklaring är att den högre jonstyrkan hos Gamble’s lösning orsakar snabb sedimentation och/eller snabb upplösning av Co NPs. Tillsättning av DPPC till en lösning av Co NPs i Gamble’s lösning släckte ut effekten, vilket indikerar en växelverkan mellan Co NPs och komponenter i Gamble’s lösning. Jämförelse av normaliserade integraler från ATR-FTIR med DPPC i Gamble’s lösning utan Co NPs och när lösningen exponerades för en Co NP film visade en signifikant skillnad efter 90 min och vid sköljning. Baserat på projektets resultat så föreslås Gamble’s lösning att bytas ut på grund av dess växelverkan med de olika komponenterna samt att liposomstorleken studeras mer i detalj. Framtida studier uppmuntras omfatta en upprepning av ATR-FTIR- mätningarna samt en frisättningsstudie av Co NPs i olika lösningar. / Nanomaterials, NMs, are increasingly produced and applied in technical applications to enhance, e.g. material properties. Since material properties change when in nanoscale, they influence their toxicological properties. There are also numerous reports of incidental formation of metallic nanoparticles, Me NPs, at construction sites, which may place workers at risk of occupational exposure by inhaling these materials. However, because of NMs size-dependent properties, current standard toxicological evaluation methods are not always well suited to these types of materials. Investigations into interactions between Me NPs and pulmonary biomolecules and method development for analysis of these interactions are therefore of high priority. In this master thesis, a description on how to dissolve the pulmonary surface active phospholipid 1,2-dipalmitoylphosphatidylcholine, DPPC, via water bath sonification has been elaborated and evaluated. The simulated lung fluid, Gamble’s solution, has been tested and evaluated as a possible medium to study interactions between DPPC and cobalt (Co) NPs under more realistic laboratory conditions. Interactions between the sample components have been studied using Photon cross-correlation spectroscopy, PCCS, Nanoparticle Tracking Analysis, NTA, and Attenuated Total Reflection Fourier Transform Infrared Spectroscopy, ATR-FTIR. Since the master thesis study was conducted during the onset of the Covid-19 pandemic, adjustments related to experimental work had to be made. PCCS showed that sonication of the DPPC solution reduced the extent of sedimentation, and the resulting size range of liposomes in solution was in the range between 50 and 70 nm in ultrapure water and between 30 and 40 nm in Gamble’s solution. Observed differences in liposome size are believed to be due to the interaction between the components of Gamble’s solution and the DPPC. This was also observed in the IR- spectra and comparable with literature findings. NTA measurements similarly visualize the relative difference in the size of the liposomes in the different media, but difficulties with the experiments may have affected the results. Gamble’s solution affected the Co NPs, such that measured particle concentrations of the NPs by means of PCCS and NTA were approximately less than half of the initial observations in ultrapure water (at 0 h). A likely explanation is that the high ionic strength of Gamble’s solution induces either fast sedimentation and/or rapid dissolution of the Co NPs. The addition of DPPC to Co NPs in Gamble’s solution cancelled this effect and suggest interactions between Co NPs and Gamble’s solution. Comparison of the normalized integrals of the ATR-FTIR- spectra of DPPC in Gamble’s solution with and without exposure to a Co NP film showed a significant difference after 90 min and upon rinsing the flow cell. Based on these results, an alternative to Gamble’s solution is suggested due to its interaction with other experimental components and that DPPC is used at a lower concentration investigation on liposome sizes are made in more detail. In addition, the ATR-FTIR measurements should be repeated, and dissolution studies of Co NPs in different synthetic media are encouraged in future studies.