Aujourd'hui, un grand nombre de nouvelles molécules peuvent être synthétisées à partir de la biomasse. Les tensioactifs dérivés de sucre sont notamment considérés comme une alternative aux tensioactifs fossiles en raison de leur biodégradabilité et de leur biocompatibilité. Cependant, les études associant la caractérisation physico-chimique et les propriétés biologiques de ce type de tensio-actifs sont limitées. Il est ainsi difficile de prédire les propriétés d'un tensioactif à partir de sa structure chimique. L'établissement d'une méthodologie permettant de relier la structure des surfactants à leurs propriétés apparait pertinent. Dans ce travail, quatre surfactants dérivés de sucre ayant chacun une chaîne C8 liée à une tête glucose ou maltose par un groupe amide ont été caractérisés par leurs propriétés tensio-actives dans différentes solutions (eau et milieu biologique). Leurs interactions avec des protéines ont également été analysées. Concernant l'évaluation des propriétés biologiques, des tests de cytotoxicité/irritation ont été effectués sur trois modèles in-vitro : 1) modèle cellulaire 20 (cellules L929 cultivées en monocouche), Il) modèle cellulaire 30 (cellules L929 cultivées dans un gel de collagène), Ill) épiderme humain reconstitué. Les résultats indiquent que les quatre surfactants synthétisés présentent de bonnes propriétés tensio-actives et trois d'entre eux sont moins cytotoxiques que des tensioactifs de référence. Plusieurs hypothèses permettant de relier la structure chimique des molécules à leurs propriétés physico-chimiques et biologiques ont été proposées. Des travaux futurs permettront d'enrichir la base de données sur les relations structure-propriétés des tensioactifs issus de la biomasse, et de l'utiliser pour synthétiser des surfactants présentant des propriétés adaptées aux applications envisagées. / Nowadays, a wide variety of new molecules can derive from biomass. Among them, the family of sugar-based surfactants, which are considered as alternatives to fossil-based surfactants, due to their relatively high biodegradability and biocompatibility, exhibit interesting properties both in terms of their self-assembly and their ability to induce biological responses. In the study, for the purpose to analyse these properties, different methodologies have been established. In this work, physico-chemistry and cellular biology methodologies are associated to analyse the properties of pre-selected molecules characterized by gradua) structure modifications. Firstly, we have screened synthesized sugar-based surfactants according to their solubility and their ability to reduce surface tension of water. Four pre-selected molecules, with a C8 chain linked to a glucose or maltose head through an amide functional group, either under the form of carbamoyl (carbohydrate scaffold bearing the carbonyl) or alkylcarboxamide (the alkyl chain bearing the carbonyl), were then dissolved in water/ cell culture media for surface tension measurements. Their behaviors in solutions were characterized by Krafft points, Critical Micellar Concentrations or self-assembling properties through different methods. To evaluate the cytotoxic/ irritant effects of these molecules on cells and tissues, 3 in-vitro models were established: I) 2D cell culture mode! (L929 cell monolayer) II) 3D ce!! culture mode! (L929 cells embedded in collagen gel) and III) Reconstituted human epidermis (differentiated human keratinocytes). Corresponding experiments were carried out on these models with increasing complexity. Results show that the synthesized sugar-based surfactants, GlulamideC8, Glu6amideC8, Glu6amideC8' and MallamideC8 can reduce the surface tension of water solution to the came level as standard surfactants (Tween 20 and Hecameg). In the meantime, GlulamideC8, Glu6amideC8' and MallamideC8 present Iess cytotoxicity effects on L929 cells both in the monolayer model and the 3D mode! than Tween 20 and Hecameg. All synthesized and standard surfactants (GlulamideC8, Glu6amideC8, Gu6amideC8', MallamideC8, Tween 20 and Hecameg) have no significant cytotoxic/ irritant effects on reconstituted human epidermis at 1000 ig/mL after 48 h of topical application. Discussions have been made according to the results of experiments to establish possible structures/ physico-chemical properties - cytotoxicity relationships of these surfactants.

Cette thèse concerne les phénomènes locaux qui se produisent dans une pile à combustible à membrane (PEMFC) fonctionnant en mode bouché. Ce mode de fonctionnement consiste à alimenter l’anode en hydrogène sec tout en maintenant sa sortie fermée ce qui favorise l’accumulation d’eau et d’azote (issus du compartiment cathodique) près de la sortie anodique. Certaines régions sont donc convenablement alimentées en gaz tandis que d’autres ne le sont plus. Ces déséquilibres s’accompagnent de hausses localisées de potentiel (à l'anode et à la cathode) qui accélèrent la dégradation du catalyseur et de son support carboné à la cathode. Afin d’étudier ces dégradations à une échelle locale, une cellule segmentée novatrice permettant la mesure simultanée des densités de courant et des potentiels locaux a été développée. Des protocoles de vieillissement accélérés reposant sur un fonctionnement prolongé en mode bouché montrent que les pics de potentiel ont pour conséquence, après quelques heures, une distribution non-uniforme de la surface active (ECSA) à la cathode et des courants le long de la cellule : les dommages sont plus prononcés dans les zones les plus touchées par le déficit en hydrogène. Des études paramétriques et un modèle numérique permettent de comprendre que le déficit en hydrogène résulte principalement de l’accumulation d’eau liquide dans les canaux de l’anode, bien que l'azote joue également un rôle. Par conséquent, la gestion de l’eau impacte fortement les variations de potentiel à la cathode et donc leurs conséquences en termes de dégradation ; basées sur ces constatations, des solutions sont proposées pour améliorer les durée de vie des piles / This work investigates the local transient phenomena occurring in proton exchange membrane fuel cells (PEMFC) operated with a dead-ended anode. The dead-end mode consists in closing the anode outlet, which leads eventually to local hydrogen starvation due to the excessive accumulation of liquid water and nitrogen (because of membrane crossover) in the anode compartment. Such fuel-starvation events may remain undetected but can entail a significant rise of the anode (and thus cathode) potentials and accelerate carbon corrosion and catalyst degradation. To access local information, we developed an innovative segmented linear cell with reference electrodes along the gas channels. By simultaneously monitoring the local potentials and current densities during operation, we assessed the impact of fuel starvation and observed strong local cathode potential excursions close to the anode outlet. Aging protocols based on fuel cell operation with a dead-ended anode (longer than in real use condition) showed non-uniform cathode ElectroChemical Surface Area (ECSA) losses and performance degradation along the cell area: the damage was more severe in the regions suffering the longest from fuel starvation. Parametric studies completed by numerical simulations showed that the fuel starvation is mainly governed by liquid water accumulation in the anode channels, as well as nitrogen crossover through the membrane. As a consequence, water management impacts significantly the cathode potential variations and thus the resulting electrode degradation. Starting from this founding, we propose strategies to improve fuel cell lifetime

Surfactants are used in a wide assortment of "down-the-drain" consumer products, yet they are often discharged in wastewater treatment plant effluent into receiving water, potentially causing environmental harm. The objective of this project was to predict surfactant toxic units and in-stream nutrients in the upper Trinity River watershed. Surface and pore water samples were collected in late summer 2005. General chemistries and surfactant toxic units were calculated. GIS models of anthropogenic and natural factors were collected and analyzed according to subwatersheds. Multiple regression analyses using the Maximum R2 improvement method were performed to predict surfactant toxic units and in-stream nutrients using GIS and in-stream values. Both geospatial and in-stream parameters generated multiple regression models for surfactant surface and pore water toxic units, as well as in-stream nutrients, with high R2 values. Thus, GIS and in-stream parameter modeling have the potential to be reliable and inexpensive method of predicting surfactant toxic units and nutrient loading in the upper Trinity River watershed.

The current increased use of antifungal agents has resulted in the development of resistance to these drugs. Search for new antifungals with different mechanisms of action overcoming the multidrug resistance is thus underway. Surface-active antifungals have the advantages of minimizing host toxicity and the emergence of drug resistance. We have developed a fluorescence method based on the use of the potentiometric fluorescent probe diS-C3(3), substrate of two major S. cerevisiae MDR pumps, Pdr5p and Snq2p. It allows us to monitor with high sensitivity and in real time changes in the activities of both pumps and also in membrane potential. We present here an efficient strategy for identifying pump inhibitors with minimal side effects on membrane integrity, and compare the potencies of different inhibitors towards MDR pumps. New efficient inhibitors of MDR pumps could potentially be used in conjunction with current antimicrobials that are MDR pump substrates. The method can be also used to determine the mechanism of action of surface-active drugs and their lowest effective concentrations.

In der serienmäßigen Verarbeitung von hochfesten Feinkornbaustählen zeigte sich, dass verschiedene Stähle gleicher Festigkeitsklasse zu stark unterschiedlichen Schweißergebnissen beim Laserstrahltiefschweißprozess führen können. Die materialbedingten Einflüsse auf das Schmelzbadverhalten sind bisher in keiner bekannten Forschungsarbeit untersucht worden. Diese Arbeit erweitert die bisherige Forschung mit neuen Erkenntnissen aus umfangreichen Materialanalysen und Schweißversuchen. Dadurch wurde es möglich, ein ganzheitliches Erklärungsmodell der materialbedingten Einflüsse beim Laserstrahltiefschweißprozess zu beschreiben. Diese Arbeit fokussierte sich einerseits auf die Analyse der chemischen Zusammensetzung der Grundmaterialien und die Auswirkungen der Legierungselemente auf die Schweißnahtvorbereitung in Kombination mit dem Vorprozess Laserstrahlbrennschneiden. Andererseits wurde gezielt die Auswirkung der chemischen Grundmaterialzusammensetzung auf das Schmelzbadverhalten im Laserstrahltiefschweißprozess untersucht. Dabei wurden die Blechstärken so variiert, dass durchgeschweißte und nicht durchgeschweißte I-Naht-Verbindungen, geschweißt unter konstanten Schweißbedingungen, analysiert werden konnten. Die Schweißparameter und der Hilfsstoffeinsatz wurden dabei konstant gehalten, sodass Vergleichsanalysen der Schweißergebnisse möglich waren. Bei durchgeschweißten Stößen wurde die Schmelzbadoberfläche, aber auch die Schmelzbadunterseite per Hochgeschwindigkeitskamera inkl. Laserlichtfilter analysiert. Bei nicht durchgeschweißten Stößen wurde die Wirkung der verschiedenen Schnittkantenzustände auf das Einschweißverhalten und die Einbrandgeometrie an mehr als 100 Makroschliffen untersucht. Die Untersuchungen zeigten, dass die Art der Schnittkantenbehandlung nach dem Laserstrahlbrennschneidprozess materialbedingt zu unterschiedlichen Schnittkantenzuständen führt. Diese können in weiterer Folge die Schweißergebnisse stark beeinflussen. Auch bei mechanisch bearbeiteten Schweißnahtvorbereitungen wurden grundwerkstoffbedingte Unterschiede in der Einbrandform und im Erstarrungsgefüge nachgewiesen. Unbehandelte und somit schnittoxidbehaftete Schnittkanten bzw. auch Schweißnahtvorbereitungen mit manuell aufgetragenem SiO2 führen zu einer Stabilisierung der Dampfkapillare und erhöhen die Einschweißtiefe signifikant. Die positive Wirkung von Oxiden, welche direkt in der Schweißfuge dem Schmelzbad zugeführt werden, wurden mit den experimentellen Versuchen in dieser Arbeit erstmals nachgewiesen. Bei den gewählten Schweißparametersätzen stellen die Oxide in der Schweißfuge die dominierende Einflussmöglichkeit beim Laserstrahltiefschweißprozess dar. Vergleiche der mechanisch-technologischen Verbindungseigenschaften bei unterschiedlichen Schnittkantenzuständen und Schweißversuche mit unterschiedlichen Schutzgaszusammensetzungen zeigten die Auswirkungen der verschiedenen Fugenvorbereitungen auf die Schweißergebnisse. Durch die Kombination der bisherigen Erkenntnisse aus der Forschung mit den neu gewonnenen Erkenntnissen aus dieser Arbeit, konnte ein ganzheitliches Erklärungsmodell aufgestellt werden, das die Einflüsse der Grundmaterialzusammensetzung entlang der Prozesskette beschreibt und die materialabhängigen Unterschiede der Schweißergebnisse aus dem Laserstrahltiefschweißprozess nachvollziehbar macht. Die Erkenntnisse dieser Arbeit ermöglichen ein erhöhtes Prozessverständnis und zeigen neue Möglichkeiten zur Effizienzsteigerung in der Blechverarbeitungsprozesskette mit Lasertechnologien.:1 Einleitung 2 Zielsetzung 3 Stand der Technik 4 Experimentelles 5 Ergebnisse der experimentellen Untersuchungen 6 Zusammenfassung und Diskussion der Ergebnisse 7 Schlussfolgerungen und Ausblick / In the industrial series processing of high-strength fine grain steels, it was found that different steels of the same strength class can lead to different welding results by the laser beam keyhole welding process. The material-related influences on the molten pool behavior have not yet been investigated in any known research. This research work extends the state of knowledge with new findings from extensive material analysis and welding tests. This new findings made it possible to describe a holistic explanatory model of the material-related influences in the laser beam keyhole welding of high-strength fine grain steels. On the one hand, this work focused on the analysis of the chemical composition of the base materials and the effects of the alloying elements on the weld preparation in combination with the laser cutting process. On the other hand, the effect of the chemical base material composition on the melt pool behavior during laser keyhole welding process was specifically investigated. The welding parameters and the use of filler material were kept constant so that comparative analysis of the welding results was possible. The sheet thicknesses were varied so that full penetration and partly penetration I-seam-butt-welds could be analyzed. While welding full penetration welds, the surface of the molten pool as well as the root of the melt pool was analyzed by a high-speed camera equipped with laser light filter. For the partly penetration welds, the effect of the different cutting edge conditions on the penetration depth and the weld penetration geometry was investigated on more than 100 macro sections. The investigations have shown that the type of cut edge treatment after the laser beam cutting process leads to different cutting edge conditions depending on the material. These different conditions can subsequently strongly influence the welding results. Base-material-related differences in the penetration shape and in the solidification structure were detected in the cross sections even on seams welded on mechanically processed edge preparations. After laser beam cutting, untreated and thus cut-oxide-containing cut edges lead to a stabilization of the keyhole and increase the penetration depth significantly. This effect could also be observed with manually applied SiO2 on the mechanically processed edge preparations before welding. The positive effects of oxides, which are existing directly in the weld preparation groove, were first detected with the experimental investigations during this work. With regard to the selected welding parameter sets, the oxides that are directly on the weld preparation edges are the dominant influence option in the laser beam keyhole welding process. Comparisons of the mechanical-technological joint properties at different cutting edge conditions and welding tests with different protective gas compositions showed the impacts of various joint preparations on the final welding results. By combining previous experience with the results of this work, a holistic explanatory model was developed, which describes the influence of the base material composition along the process chain and makes the material-dependent differences of the welding results of the laser beam keyhole welding process comprehensible. The findings of this work enable a better understanding of the process and show new possibilities for increasing efficiency in the concerned sheet metal processing chain with laser technologies.:1 Einleitung 2 Zielsetzung 3 Stand der Technik 4 Experimentelles 5 Ergebnisse der experimentellen Untersuchungen 6 Zusammenfassung und Diskussion der Ergebnisse 7 Schlussfolgerungen und Ausblick

Indiana University-Purdue University Indianapolis (IUPUI) / Toner analysis has become an area of increased interest due to the wide availability of laser printers and photocopiers. Toner is most often encountered on paper in questioned document analysis. Because of this, it is important to develop methods that limit the interference of paper without damaging or destroying the document. Previous research using Fourier transform infrared spectroscopy (FTIR) has differentiated toners based on their polymer resin components. However, Raman spectroscopy and chemometric analysis are not typically used for the examination of this material. Raman spectroscopy is a popular tool for the chemical analysis of pigmented samples and was used to characterize cyan, yellow, and magenta toners. Analyses were performed using a dispersive micro-Raman spectrometer equipped with a 785nm diode laser, a CCD detector, and an objective at 20X magnification. One hundred samples of each color toner were collected. Three different and separate methods were developed for cyan, yellow, and magenta toners on paper to optimize results. Further analysis of the magenta toners was excluded due to a weak signal and significant paper interference. The data collected from the analyses of the blue and yellow toners was then processed using a combination of statistical procedures, including principal component analysis (PCA), agglomerative hierarchal clustering (AHC), and discriminative analysis (DA). Ninety-six blue toners were analyzed by PCA and three classes of spectra were suggested. Discriminant analysis showed that the three classes were well-differentiated with a cross-validation accuracy of 100% for the training set and 100% cross-validation accuracy for the external validation set. Eighty-eight yellow toners were analyzed by AHC and four classes of spectra were suggested. Discriminant analysis showed good differentiation between the classes with a cross-validation accuracy of 95.45% for the training set, but showed poor differentiation for the external validation set with a cross-validation accuracy of 72%. While these toners were able to be discriminated, no correlation could be made between the manufacturer, printer make and model, and the toner sample.

No / PURPOSE: Self-emulsifying systems (SES) emulsify spontaneously to produce fine oil-in-water emulsion when introduced into aqueous phase. The self-emulsification process plays an important role during formation of emulsion. The objective of current work was to understand and explore the inner structuration of SES through controlled hydration and further to study the influence of additive on the same which ultimately governs performance of final formulation in terms of droplet size. METHODS: Droplet size of final formulations containing structural analogues of ibuprofen was determined. Microstructural properties of intermediate hydrated regimes of SES were investigated using techniques such as small angle X-ray scattering, differential scanning calorimetry and rheology. RESULTS: The current work established inverse relationship between droplet size of the formulations containing structural analogues of ibuprofen and their Log P values. Microstructural analysis of intermediate hydrated regimes of the prepared samples showed formation of local lamellar structure. Structural analogues of ibuprofen significantly altered microstructure of lamellae which was well correlated with the droplet size of final formulations. In vitro drug release study showed increase in dissolution rate of lipophillic drugs when formulated as SES. CONCLUSION: The current work emphasizes the fact that tailor-made formulations can be prepared by controlling the properties of intermediate regimes.

The development of analytical methods for emerging contaminants creates many unique challenges for analytical chemists. By their nature, emerging contaminants have inherent data gaps related to their environmental occurrence, fate, and impact. This dissertation is a compilation of three studies related to method development for the structural identification of emerging contaminants, the detection and quantification of chemicals used in unprecedented quantities and applications, and the extraction of compounds from complex matrices where the solvent-solute-matrix interactions are not completely understood. The three studies present analytical methods developed for emerging contaminants in complex matrices, including: fluorochemical surfactants in aqueous film-forming foams, oil dispersant surfactants in seawater, and fullerene nanomaterials in carbonaceous solids. Aqueous film-forming foams, used in military and commercial firefighting, represent environmentally-relevant commercial mixtures that contain a variety of fluorochemical surfactants. Combining the surfactant-selective ionization of fast atom bombardment mass spectrometry with high resolution mass spectrometry, chemical formulas for 11 different fluorochemical classes were identified. Then AFFF-related patents were used to determine the structures. Of the eleven classes of fluorochemicals, ten have little, if any, data on their environmental occurrence, fate, and potential impacts in the peer-reviewed literature. In addition, nine of the identified classes had either cationic or zwitterionic functionalities and are likely to have different transport properties compared to the well-studied anionic fluorochemicals, such as perfluorooctanoate. After the Deepwater Horizon oil spill in the summer of 2010, one of the emergency response methods for the mitigation of the oil's environmental impact was the use of unprecedented amounts of oil dispersant to break down the oil slick and encourage biodegradation. This event illustrated the need for rapid analytical method development in order to respond to the potential environmental disaster in a timely manner. Using large volume injection liquid chromatography with tandem mass spectrometry, an analytical method was developed for the trace analysis of the multiple dispersant surfactant classes and the potential degradation products of the primary surfactant. Limits of detection ranged from 49 ��� 3,000 ng/L. The method provided excellent recovery (86 ��� 119%) and precision (10 ��� 23% RSD), while also accommodating for the high salinity of seawater samples and analyte contamination. Despite the fact that fullerene nanomaterials have been studied for almost three decades, research is still being conducted to fully understand the environmental properties of these materials. Previous studies to extract fullerenes from environmental matrices have resulted in low efficiency, high variability, or the extraction efficiencies have gone unreported. Extraction by ultrasonication with toluene and 1-methylnaphthalene increased the recovery 5-fold of a spiked, isotopically-labeled C������ surrogate from carbon lampblack as compared to that of the conventional approach of extracting with 100% toluene. The study revealed the importance of evaluating experimental variables such as extraction solvent composition and volume, and sample mass, as they have a significant impact on the quantitative extraction of fullerenes from environmental matrices. / Graduation date: 2013 / Access restricted to the OSU Community at author's request from Aug. 15, 2012 - Aug. 15, 2013