Complex Organic Molecules (COMs) have been detected in objects across different stages of stellar evolution. Many of these COMs are expected to form on interstellar ice and transfer later to the... Show moreComplex Organic Molecules (COMs) have been detected in objects across different stages of stellar evolution. Many of these COMs are expected to form on interstellar ice and transfer later to the gas phase. However, due to the challenge of detecting and assigning molecules in interstellar ice observations, the only frozen COM that has been unambiguously identified is methanol. This scenario is about to change, as the exceptional capabilities of the James Webb Space Telescope (JWST) enable the observation of weak signatures of molecules in interstellar ice.This thesis has a main focus on laboratory studies to support interstellar ice observation with the JWST. The results of the spectroscopic characterization of three COMs, acetone, methylamine, and methyl cyanide mixed in interstellar ice analogs are presented in Chapters 3, 4, and 5, respectively. The potential of their absorption features to trace these species in JWST observations is also discussed. Chapter 6 presents a new experimental approach to studying morphological changes in frozen CO, which is important to understand its morphology in space. Chapter 7 presents a computational study that simulates the infrared spectra of small fullerenes (between 44-70 C atoms) and provides insights for future JWST searches for these molecules Show less
Barrier function is the natural role of the skin. The lipid matrix present in the outermost layer of the skin, the stratum corneum is important for this function. Barrier impairment and altered... Show moreBarrier function is the natural role of the skin. The lipid matrix present in the outermost layer of the skin, the stratum corneum is important for this function. Barrier impairment and altered lipid composition are observed in several inflammatory skin diseases including atopic dermatitis and psoriasis. However, the relationship between the lipid properties and barrier function is not comprehended.In this project, a lipid model was prepared from synthetic lipids that closely resemble the stratum corneum lipid composition and organization. Subsequently, diseased skin models were developed to mimic various abnormalities in lipid composition observed in atopic dermatitis patients’ skin. Biophysical methods were used to monitor the changes in lipid organization in these models. Diffusion studies and trans-epidermal water loss measurements were performed to monitor the barrier function. This allowed the determination of the changes in lipid properties that were most instrumental in reducing the lipid barrier.This thesis further describes the use of simple skin lipid model membranes incorporating fewer components to provide a detailed insight into the relationship between lipid composition, lipid organization, and the skin barrier. The information gained in this project offers the opportunity to develop a new generation of formulations to treat these patients. Show less
This thesis is largely an experimental study on the formation of solid-state simple and complex organic molecules in the H2O-rich and CO-rich ice phases of dense interstellar clouds and dark cores.... Show moreThis thesis is largely an experimental study on the formation of solid-state simple and complex organic molecules in the H2O-rich and CO-rich ice phases of dense interstellar clouds and dark cores. Astronomical ice observations are also presented and are strongly linked to the experimental work. For decades, it has been realized that particularly complex organic molecules can be formed at extremely low temperatures with the aid of 'energetic' particles, such as UV photons. In this thesis, it is clearly shown that complex organic molecules can also be formed without 'energetic' particles. The experimental laboratory work is supported by computational calculations to constrain which molecules are more or less likely to form under the extreme conditions of interstellar clouds. Show less
For decades a large amount of research has dealt with membrane interactions of peptides and proteins as well as peptide-peptide interactions to understand the mechanisms of essential biological... Show moreFor decades a large amount of research has dealt with membrane interactions of peptides and proteins as well as peptide-peptide interactions to understand the mechanisms of essential biological processes such as protein-driven vesicle budding and fission, cell penetration and lysis by peptides, and of course protein-driven membrane fusion. The advance of these fields, in combination with recent progress in cell biology, has inspired chemists to mimic these biological processes with simple model systems. However, it becomes apparent that these model systems are more complex than initially thought and the lessons that were learned from natural systems can also be applied here. The work reported in this thesis applied and extended classical methods for the study of peptide-peptide and peptide-membrane interactions to study the properties of the fusogenic coiled-coil forming lipopeptides in different membrane model systems or in solution. Hypotheses were constructed and tested based on the current biochemical and biophysical models of natural membrane fusion. Taken together, the results reported here led to a new perspective on lipopeptide mediated vesicle fusion. Show less
The Spectral Energy Distributions (SEDs) of star-forming regions and starburst galaxies are unique tracers of the star formation processes in these environments, since they contain information on... Show moreThe Spectral Energy Distributions (SEDs) of star-forming regions and starburst galaxies are unique tracers of the star formation processes in these environments, since they contain information on the escaping and processed photons emitted by newly formed massive stars. Understanding these internal processes is crucial in our physical interpretation of observations of unresolved star formation in the Universe. In the __rst part of this thesis, we study the physical conditions in resolved starburst regions using Bayesian __tting of their spatially integrated infrared SEDs, including both the thermal continuum and the atomic emission lines. We then apply the method to unresolved starburst to learn about their star formation physics. Our approach leads to robust constraints on physical parameters such as age, compactness, and amount of currently ongoing star formation in starburst, which are otherwise biased by model degeneracies, and allows us to link the resolved properties of giant H II regions to the star formation process at larger scales. In the second part of this thesis, we discuss the wavelength calibration of the next instrument to study the midinfrared spectral properties of starbursts, with improved resolution and sensitivity: the mid-infrared instrument (MIRI), which will __y onboard the James Webb Space Telescope in 2018. Show less
This thesis focuses on the interplay of the young star and its protoplanetary disk, on the evolution of the dust particles that make up the protoplanetary disk surrounding the young star, and thus... Show moreThis thesis focuses on the interplay of the young star and its protoplanetary disk, on the evolution of the dust particles that make up the protoplanetary disk surrounding the young star, and thus on the very first stage of the formation of planets like those that compose our own Solar system. Show less
