Atomic force microscopy (AFM) can be used to acquire high-resolution topographical images of surfaces, but has the additional capability of detecting the local nanometer scale mechanical properties. For these reasons, it becomes a standard research tool in the surface science recently. In this paper, we used AFM to measure the several properties of two different human hepatocellular carcinoma cell lines, Hep G2 ( known as well differentiated and more highly carcinomatous hepatoma cell lines ) and SK-HEP-1 ( known as poorly differentiated and more lightly carcinomatous hepatoma cell lines ) cells fixed on the glass substrate, which including the surface morphology and the relationship between the cantilever deflections and loading forces ( force curve ). Considered the heterogeneous characteristics of the cell surface, the preferred experimental method is to make pixel-by-pixel force curves in a designated area ( force map ) , both adhesion forces and elasticity associated with different locations on the cell surfaces will be obtained. Finally, we use Hertzian model to calculate Young's modulus of Hep G2 and SK-HEP-1 respectively. Based on these results, we can understand the surface properties of two human hepatocarcinoma cell lines with different differentiated stage. The results showed the difference of the morphology, height, cell migration, degree of cell aggregation, roughness, elasticity, adhesive force of two cells. SK-HEP-1 cell has the wide distance of the folds, better cell migration, homogeneous properties of elasticity. It can be assumed that the SK-HEP-1 cells have a dense network structure of actin filaments under the cell membrane like branches (branched networks); Hep G2 cell has the narrow distance of the folds, poor cell migration, heterogeneous properties of elasticity. It can be assumed that the Hep G2 cells have the individual actin filaments and cross-linked network structure of actin filaments under the cell membrane. The above results can be speculated that the elastic properties of the membrane surface will be influenced of actin filaments.

An underinhibited system is defined as a system where an insufficient amount of thermodynamic inhibitor is present to prevent hydrate formation. Underinhibition might occur due to malfunctioning of equipment, temporary limitations in the inhibitor supplies or operational limitations or errors. Understanding the plugging risk of such systems is important in order to take the correct precautions to avoid blocked flowlines. In this paper we summarize the experimental efforts for the last decade within StatoilHydro on the hydrate plugging risk in underinhibited systems. The flow simulator has been used as the main experimental equipment. The overall results for systems underinhibited with ethylene glycol or methanol show that the plugging potential increases up to a maximum at concentrations around 10-15 wt%. At higher concentrations the plugging potential reduces compared to the uninhibited system. The results can be explained as follows: As water is converted to hydrates in a system containing a thermodynamic inhibitor, the inhibitor concentration will increase until the remaining aqueous phase is inhibited. This self-inhibited aqueous phase will wet the hydrate particles, giving raise to the characteristic term of “sticky” hydrate particles. The aqueous layer surrounding the hydrate particles will form liquid bridges, by capillary attractive forces, upon contact with other hydrate particles or the pipe wall. During the hydrate formation period, there is also a possibility that some of the liquid bridges are converted to solid ones, strengthening the agglomerates. Depending on the oil-water interfacial tension, the phase ratio between the aqueous phase and the solid hydrates and the conversion of liquid bridges to solid ones, this leads to increased plugging risk at lower concentrations of inhibitor (< 20 wt%) and reduced risk at higher concentrations as compared to the uninhibited system.

The primary focus of this study is the reduction of sensitivity to contamination of the battery pack surfaces. During the project, information on adhesion mechanisms that cause particles to accumulate on surfaces has been collected through literature research. This has been done to create a fundamental understanding regarding the factors that affect dust and particle accumulation. In addition, an in-depth study of articles concerning the modification of surface structure has been carried out. In connection with the literature study, an experimental analysis was carried out where a number of surfaces provided by Scania were examined to understand their structure and properties. This was done in order to identify suitable surface treatments/methods that could be applied. The experimental results show that all the surfaces consist of only micro-level structures. Two of the samples showed increased risk for dust accumulation due to one of them having a step profile and the other having a wavy surface structure with peaks and valleys. Previous research suggests that surfaces that are structured on the micro- and nano-level are essential to achieve dust- and particle-free/repellent surfaces. By structuring surfaces at the micro- and nano-level, a so-called hierarchical structure inspired by the natural self-cleaning mechanisms of the lotus leaf can be achieved. This results in surfaces with a high water contact angle and low surface energy, which contribute to minimized adhesion forces and in turn particle repellent surfaces.

In this thesis, a direct method of Atomic Force Microscopy (AFM) technique has been developed to measure the adhesion forces between BSA and two different surfaces: mica (a hydrophilic surface); and polystyrene (a hydrophobic surface); in PBS solution. We have shown possible to measure interactions between proteins and substrate surface directly without any modification to the substrate and the AFM tip; this means protein molecules can keep the natural elastic property within the force measurements. The average measured value of adhesion forces between BSA and mica is 0.036 ± 0.002 nN, and between BSA and polystyrene is 0.066 ± 0.003 nN. The polystyrene surface is more adhesive to BSA than the mica surface. This is consistent with previous research, which assessed that hydrophobic surfaces enhance protein adhesion but hydrophilic surfaces do not.

Cette étude vise à une meilleure compréhension des phénomènes rencontrés en filtration des aérosols nanométriques, c’est-à-dire inférieurs à 100 nm, neutres et/ou chargés. Pour ce faire, trois différents types de média ont été étudiés : des grilles, en acier et matières synthétiques, des filtres non tissés, en fibres de verre ou polymériques, et des lits granulaires, constitués de billes d’acier ou de zéolithe. Il ressort des résultats expérimentaux obtenus que quel que soit le média testé, l’efficacité de collecte des particules augmente lorsque le diamètre de l’aérosol diminue, et ce jusque 4 nm. Ceci entre en contradiction avec l’approche théorique dite du rebond thermique, développée par Wang et Kasper en 1991, selon laquelle l’efficacité de collecte serait susceptible de diminuer en-dessous de 10 nm. La vérification des calculs de Wang et Kasper permet d’expliquer cette incohérence, et montre, à partir de valeurs plus réalistes de l’énergie d’adhésion particule-fibre, que si le rebond thermique existe, celui-ci ne pourra se manifester qu’en-dessous de 1 nm, au mieux. Ainsi, les perméances expérimentales des différents médias testés ont pu être modélisées en tenant compte des mécanismes de collecte par diffusion et/ou par effets électrostatiques. Une étude originale sur les performances, dans le domaine nanométrique, de filtres en fibres de verre intentionnellement percés complète ce travail. Pour un même média fibreux, la perméance augmente avec le diamètre de perforation réalisée. Par ailleurs, pour une taille de perforation donnée, la perméance devient indépendante du diamètre des particules en-dessous d’une taille limite, fonction de la dimension de la perforation. Il a enfin été mis en évidence que la baisse d’efficacité est d’autant plus importante que la résistance à l’écoulement de l’air du filtre est importante. Un modèle semi-empirique, fondé sur la différenciation du flux d’aérosol traversant la fuite du flux traversant le matelas fibreux résiduel du filtre, permet de bien représenter ces états de fait / This study aims to better understand the mechanisms encountered in nanoparticles aerosol filtration, the particles being charged or not. Three different types of media were studied: stainless steel or synthetics wire screens, unwoven filters in glass or polymer fibres, and at last, granular beds made from steel or zeolite balls. Experimental results show that, whatever the media, collection efficiency increases as the particle diameter decreases down to 4 nm. This point conflicts with the so-called thermal rebound effect developed by Wang and Kasper in 1991, according to which collection efficiency could decrease below 10 nm. The checking of Wang and Kasper’s calculations enables to explain this discrepancy and shows from more probable particle-to-fibre adhesion energy values that if thermal rebound phenomenon exists, it would only be measurable below 1 nm. Then, experimental points can be modelled from both diffusion and electrostatic forces collection mechanisms. An investigation on the filtration behaviour of fibreglass filters in the nanometric domain when intentionally-pierced with calibrated needles completes the above-mentioned works. For a same media, penetration increases as the leak diameter does. On the other hand, for a given hole size, penetration becomes independent of the particle diameter below a critical scale, which is a function of the leak diameter. It was lastly shown that the efficiency of a pierced media decreases all the more that its air flow resistance is higher. A semi-empirical model based on the differentiation between the aerosol flow across the leak and the one through the residual fibrous bed of the filter enables to well represent these points

Diese Arbeit setzt sich mit der Messung und Modellierung von Haftkräften auf rauen Oberflächen auseinander, wobei Filtermaterialien aus dem Sonderforschungsbereich 920 mittels Rasterkraftmikroskopie-Methoden untersucht wurden. Durch eine Vielzahl an Haftkraftmessungen konnte gezeigt werden, dass für schlecht benetzende Oberflächen die Rauheit zur Erhöhung der attraktiven Kräfte führt, da vermehrt mit Kapillarwechselwirkungen zu rechnen ist. Aus diesem Grund erfolgte eine Charakterisierung der Oberflächenmorphologien der Filtermaterialproben und eine kritische Bewertung von Modellen, welche aus Kontaktwinkeldaten die Oberflächenenergien ermitteln. Im Modellierungsteil der Arbeit wurden gängige van der Waals-Kraftmodelle mit Berücksichtigung von Retardationseffekten untersucht. Weiterhin wurden AFM-Scans mit dem Schichtmodell von Dagastine verbunden sowie für die Bewertung von Kapillarkraftmodellen verwendet.:Abbildungsverzeichnis Tabellenverzeichnis 1 Einleitung 2 Stand der Technik 2.1 Reinigung von Metallschmelzen 2.1.1 Stellung des Sonderforschungsbereichs 920 innerhalb der Thematik der Metallschmelzereinigung 2.1.2 Inklusionen in Metallschmelzen - Schmelzprozess, relevante Einschlusstypen und Problematik verunreinigter Gussprodukte 2.1.3 Möglichkeiten der Metallschmelzereinigung 2.1.4 Metallschmelzefiltration 2.2 Rasterkraftmikroskopie 2.2.1 Funktionsweise, Kraftspektroskopie und Imaging 2.2.2 Colloidal Probe Technik 2.3 Benetzung und deren Phänomene 2.3.1 Ansätze zur Quantifizierung von Benetzungsgrößen 2.3.2 Diskussion bezüglich der Oberflächenenergiemodelle 2.3.3 Realsystem: Benetzungsphänomene bei Metallschmelzen auf Keramiken am Beispiel Aluminium 2.4 Haftkräfte und deren Berechnung 2.4.1 DLVO-Kräfte: van der Waals-Wechselwirkungen 2.4.2 nonDLVO-Kräfte 2.4.3 Nanoblasen und Kapillarkräfte 2.4.4 Haftkräfte unter erhöhten Temperaturen, Sinterung 2.4.5 Haftkräfte auf rauen Oberflächen 2.4.6 Kontaktmechanik 2.5 Genutztes Modellsystem, Abgrenzung der Arbeit 3 Material und Methoden 3.1 Material 3.1.1 Substrate 3.1.2 Partikel 3.1.3 Modellschmelze Wasser, Flüssigkeiten für die Kontaktwinkelmessung 3.2 Methoden 3.2.1 Kontaktwinkelmessgerät G10 3.2.2 Rasterkraftmikroskope XE-100 und UHV750 3.2.3 MatLAB-Skripte 3.2.4 Silanisierung 3.3 Vorbetrachtungen 3.3.1 Berechnung der Hamaker-Konstanten der untersuchten Stoffsysteme 3.3.2 Bedeutung eines einheitlichen Protokolls bei AFM- und KWMessungen 4 Auswertung 4.1 Charakterisierung der untersuchten Oberflächen bezüglich ihrer Rauheit mithilfe von AFM-Scans 4.1.1 Kontaktmechanik und sinnvolle Wahl der Scan-Größen sowie Lateral-Auflösung 4.1.2 Höhenprofile (z-Werte) der Filtermaterialien 4.1.3 Rauheitskenngrößen der AFM-Scans 4.1.4 Zusammenfassung 4.2 Kontaktwinkelmessungen und Oberflächenenergieverteilungen 4.2.1 Kontaktwinkelmessungen auf den Filtermaterialien 4.2.2 Oberflächenenergie - Komponentenansätze 4.2.3 Oberflächenenergie - Equation of State 4.2.4 Abschätzen der Hamaker-Konstanten aus der Oberflächenenergie des Feststoffs 4.2.5 Zusammenfassung 4.3 Ergebnisse Kraftspektroskopie 4.3.1 Experimentelle Ergebnisse - Einflussfaktoren Benetzbarkeit, Rauheit und Gasübersättigung 4.3.2 Sondergeometrien 4.3.3 Nachbetrachtung zu den Ergebnissen des Modellsystems 4.3.4 HT-Messungen mit dem Rasterkraftmikroskop 4.3.5 Zusammenfassung 5 Modellierung 5.1 Berücksichtigung von Retardation bei gängigen van der Waals- Kraftmodellen auf rauen Oberflächen in der Mechanischen Verfahrenstechnik 5.2 Van der Waals-Kraft-Modelle für raue Oberflächen zur Beschreibung der experimentellen Daten 5.3 Dagastines Modell in Kombination mit dem Cooper-Ansatz 5.4 Kapillarkräfte durch Nanoblasen auf rauen Oberflächen 5.4.1 Zusammenfassung 6 Zusammenfassung und Ausblick 6.1 Zusammenfassung 6.2 Ausblick 7 Anhang 7.1 Ergänzungen zum Kapitel Stand der Technik 7.2 Ergänzungen zum Kapitel Material und Methoden 7.3 Ergänzungen zum Kapitel Auswertung: Rauheit 7.4 Ergänzungen zum Kapitel Auswertung: Kontaktwinkelmessungen und Oberflächenenergien 7.5 Ergänzungen zum Kapitel Auswertung: Literatur- und Messdaten 7.6 Ergänzungen zum Kapitel Auswertung: Modellierung Literaturverzeichnis