The objective of this thesis was to further develop a methodology for surface tension measurement called Axisymmetric Drop Shape Analysisn(ADSA) and to adapt it to studies of lung surfactants, i.e. the material that coats and facilitates the functioning of the lungs of all mammals. The key property of a functioning lung surfactant is its surface tension, which can reach extremely low values. Such values are difficult to measure; but a certain configuration of ADSA, using a constrained sessile drop (ADSA--CSD), is capable of performing such measurements. Clinically, lung surfactant films can be altered from both sides, i.e. from the airspace as well as from the bulk liquid phase that carries the film. Therefore, being able to access the interface from both sides is important. Here, ADSA--CSD was redesigned to be used as a micro film balance allowing access to the interface from both gas- and liquid-side. This allows deposition from the gas side as well as complete exchange of the bulk liquid phase. The new design was used to study lung surfactant inhibition and inhibition reversal. A dynamic compression-relaxation model (CRM) was developed to describe the mechanical properties of lung surfactant films by investigating the response of surface tension to changes in surface area. The model evaluates the quality of lung surfactant preparations -- beyond the minimum surface tension value -- and calculates the film properties, i.e. elasticity, adsorption and relaxation, independent of the compression protocol. The accuracy of the surface tension measurement can depend on drop size. A detailed analysis of drop shapes and accuracy of measured surface tension values was performed using a shape parameter concept. Based on this analysis, the design of ADSA--CSD was optimized to facilitate more accurate measurements. The validity analysis was further extended to the more conventional pendant drop setup (ADSA--PD). An overall upgrade of both hardware and software of ADSA--CSD, together with extensive numerical work, is described and applied to facilitate a more efficient operation. Finally, it is noted that the ADSA--CSD setup developed here can be used for a wide range of colloid and surface chemical applications.

Surfactant protein D (SP-D) is an important innate immune collectin involved in uptake and clearance of microbes and allergens in the lungs. SP-D has been shown to ameliorate allergic asthma reactions in mice; however, the mechanisms for this are not fully understood. We investigated the role of SP-D in the uptake and clearance of the model allergen ovalbumin (OVA) by macrophages. We discovered that SP-D does not bind OVA but binds fractions with contaminating proteins; ovomucin and ovomacroglobulin. We extended these findings to show that SP-D binds human alpha-2-macroglobulin (A2M) in its cleaved or intact state, in a concentration-, calcium-, and carbohydrate-dependent manner. A2M increases the innate immune potential of SP-D by increasing its ability to agglutinate the bacteria Escherichia coli and Bacillus subtilis. We found that SP-D does not increase the uptake of OVA by murine macrophage cell lines, or by alveolar macrophages in vivo in BALB/cJ mice.

The objective of this thesis was to further develop a methodology for surface tension measurement called Axisymmetric Drop Shape Analysisn(ADSA) and to adapt it to studies of lung surfactants, i.e. the material that coats and facilitates the functioning of the lungs of all mammals. The key property of a functioning lung surfactant is its surface tension, which can reach extremely low values. Such values are difficult to measure; but a certain configuration of ADSA, using a constrained sessile drop (ADSA--CSD), is capable of performing such measurements. Clinically, lung surfactant films can be altered from both sides, i.e. from the airspace as well as from the bulk liquid phase that carries the film. Therefore, being able to access the interface from both sides is important. Here, ADSA--CSD was redesigned to be used as a micro film balance allowing access to the interface from both gas- and liquid-side. This allows deposition from the gas side as well as complete exchange of the bulk liquid phase. The new design was used to study lung surfactant inhibition and inhibition reversal. A dynamic compression-relaxation model (CRM) was developed to describe the mechanical properties of lung surfactant films by investigating the response of surface tension to changes in surface area. The model evaluates the quality of lung surfactant preparations -- beyond the minimum surface tension value -- and calculates the film properties, i.e. elasticity, adsorption and relaxation, independent of the compression protocol. The accuracy of the surface tension measurement can depend on drop size. A detailed analysis of drop shapes and accuracy of measured surface tension values was performed using a shape parameter concept. Based on this analysis, the design of ADSA--CSD was optimized to facilitate more accurate measurements. The validity analysis was further extended to the more conventional pendant drop setup (ADSA--PD). An overall upgrade of both hardware and software of ADSA--CSD, together with extensive numerical work, is described and applied to facilitate a more efficient operation. Finally, it is noted that the ADSA--CSD setup developed here can be used for a wide range of colloid and surface chemical applications.

Surfactant protein D (SP-D) is an important innate immune collectin involved in uptake and clearance of microbes and allergens in the lungs. SP-D has been shown to ameliorate allergic asthma reactions in mice; however, the mechanisms for this are not fully understood. We investigated the role of SP-D in the uptake and clearance of the model allergen ovalbumin (OVA) by macrophages. We discovered that SP-D does not bind OVA but binds fractions with contaminating proteins; ovomucin and ovomacroglobulin. We extended these findings to show that SP-D binds human alpha-2-macroglobulin (A2M) in its cleaved or intact state, in a concentration-, calcium-, and carbohydrate-dependent manner. A2M increases the innate immune potential of SP-D by increasing its ability to agglutinate the bacteria Escherichia coli and Bacillus subtilis. We found that SP-D does not increase the uptake of OVA by murine macrophage cell lines, or by alveolar macrophages in vivo in BALB/cJ mice.

Lycopene has recently received interest as an antioxidant in human tissues. These same antioxidant properties present challenges in preventing oxidative degradation within food products. In this research, degradation of lycopene in model emulsion systems was examined to better understand the chemical stability of this potential functional food ingredient.

Emulsions and foams are thermodynamically unstable dispersions that will eventually succumb to coalescence, leading to phase separation. However the kinetic stability of emulsions and foams can vary from transiently stable systems with lifetimes of seconds to indefinitely stable systems with lifetimes of many years. Understanding and controlling emulsion and foam stability is fundamental to their widespread application in consumer products and industrial processes. Designed stimuliresponsive peptide surfactants that allow the stability of emulsions and foams to be controlled by changes in solution conditions have recently been developed at the University of Queensland. The research objective of this thesis was to establish the mechanism by which these switchable biosurfactants control emulsion and foam stability and hence contribute design rules for future generations of peptide surfactants. In particular, research focused on the control of emulsion coalescence kinetics and the fundamental insights that these peptide-based emulsions provide into the coalescence phenomena. It was proposed that these switchable peptide surfactants allow the mechanical strength of the viscoelastic surfactant layer to be decoupled from other contributions to emulsion stability. It was found that the established Derjaguin– Landau–Vervey–Overbeek (DLVO) theory, which is frequently used as the basis for predicting emulsion stability, was not able to describe the stability switching observed in the peptide-based emulsions. Different designs of peptide surfactant were used to demonstrate that the kinetics of emulsion coalescence could be shifted by changing the interfacial elasticity, clearly illustrating the critical role of the surfactant layer’s mechanical properties in the coalescence mechanism. Where the peptide-surfactant-based emulsions enabled triggering a rapid transition to coalescence from a flocculation stable system it was shown that both the electrostatic repulsion (flocculation barrier) and the interfacial elasticity (coalescence barrier) were switched. This work made use of a number of experimental techniques to study the coalescence mechanism, including the observation of droplet interactions in microfluidic channels. The switchable peptide surfactants were shown to enable triggered coalescence in droplet based microfluidics, something that had hereto with proved an intractable challenge for surfactant containing oil-in-water systems. Having established the importance of the mechanical properties of the adsorbed peptide layer in enabling control over coalescence kinetics, it was of interest to study the effect of adding other surfactant species. Mixed surfactant systems are likely to be encountered in industrial applications or commercial products. The peptide surfactant AM1 was mixed with the common anionic surfactant sodium dodecyl sulfate (SDS) and synergistic behaviour was identified, including enhanced interfacial adsorption and reversible association of structures in the bulk solution. Furthermore the interfacial layers formed by AM1-SDS retained the switchable mechanical behaviour despite considerable increases in the absolute mechanical strength.

"March 2001". / Bibliography: leaves 193-238. / vii, 238 leaves : ill. (some col.) ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Relates changes in the development of the pulmonary surfactant system in response to birth strategy, lung morphology and phylogeny in order to determine the extent of conservation in this process, by quantifying the total of phsospholipid, disaturated phospholipid and cholesterol in the lung washings of embryonic and hatchling chickens, oviparous bearded dragons and viviparous sleepy lizards, snapping turtles and green sea turtles throughout the final stages of incubation and gestation. Finds that the pattern of development of pulmonary surfactant lipids is consistent with that of mammals. / Thesis (Ph.D.)--University of Adelaide, Dept. of Physiology, 2001

"March 2001". / Bibliography: leaves 193-238. / vii, 238 leaves : ill. (some col.) ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Relates changes in the development of the pulmonary surfactant system in response to birth strategy, lung morphology and phylogeny in order to determine the extent of conservation in this process, by quantifying the total of phsospholipid, disaturated phospholipid and cholesterol in the lung washings of embryonic and hatchling chickens, oviparous bearded dragons and viviparous sleepy lizards, snapping turtles and green sea turtles throughout the final stages of incubation and gestation. Finds that the pattern of development of pulmonary surfactant lipids is consistent with that of mammals. / Thesis (Ph.D.)--University of Adelaide, Dept. of Physiology, 2001

Tez (Tıpta Uzmanlık) - Süleyman Demirel Üniversitesi, Tıp Fakültesi, Kadın Hastalıkları ve Doğum Anabilim Dalı, 2005. / Bibliyografya var.

Thesis (Ph.D)--Murdoch University, 2007. / Thesis submitted to the Faculty of Sustainability, Environmental and Life Sciences. Includes bibliographical references (leaves [134]-158).