Berlin, Techn. Univ., Diss., 2002. / Computerdatei im Fernzugriff.

Hannover, Universiẗat, Diss., 2003.

München, Techn. Universiẗat, Diss., 2000.

München, Techn. University, Diss., 2003.

Hannover, Universiẗat, Diss., 2000.

Hannover, University, Diss., 2004 und Università degli Studi di Trento, Diss., 2004.

Siegen, Universiẗat, Diss., 1999.

In this thesis it will be shown that the hydrogen atom has a SU(2) × SU(2) symmetry generated by the quantum mechanical angular momentum and Runge-Lenz vector operators. Additionally, the hydrogenic atom will be studied with supersymmetric methods to identify a supersymmetry that relates different such systems. This thesis is intended to present the material in a manner accessible to people without background in Lie groups and supersymmetry, as well as fill in some calculations between steps that are not spelt out in the litterature.

A Vernier spectrometer is built with a near-infrared mode-locked Er:doped fiber laser, a Fabry-Perot cavity with finesse of 1000, a diffraction grating and a photo detector. The optical cavity provides high sensitivity in absorption detection by enhancing the interaction length of the light with molecular species contained in the cavity. Coupling an optical frequency comb to the cavity provided a broadband spectral bandwidth with high precision to measure the absorption of several molecular species simultaneously. Also, by using the optical cavity as a filter, transmission of some bunch comb lines was achieved. This comb filtering together with a simple grating and a photodiode formed the Vernier detection technique to provide very fast measurements while it kept the setup very simple and compact. The system allows to detect carbon dioxide in the air and water vapor and OH radicals in the flame in a spectrum spanning from 1550 nm to 1590 nm, approximately. The retrieved spectrum has a resolution of 9.3 GHz being acquired in 0.05 s.

A common consequence of protein denaturation is the loss of biological activity. Natural osmolytes such as Trimethylamine N-oxide (TMAO) contribute to protein folding, whereas other osmolytes such as urea act as an agent in the denaturation of proteins. Many studies have shown that denaturation of proteins could occur for certain concentrations of urea, however, this effect could be prevented with the presence of Trimethylamine N-oxide (TMAO) molecules. The aim of the present study is to find out the mechanism of TMAO as a protein stabilizer against urea. Firstly, Molecular Dynamics simulations were carried out for 1, 8, 27 and 64 TMAO molecules. The time-average location of the TMAO molecules during the simulation was studied by the partial density. These simulations examine if TMAO is amphiphilic molecule, i.e contains both hydrophobic and hydrophilic parts. However, these results might not be representative due to bad statistics. Secondly, an experiment ran at BESSY II at Helmholtz-Zentrum Berlin using X-ray Photoelectron Spectroscopy in liquids. In this experiment, Lauryldimethylamine oxide(LDAO) was used instead of Trimethylamine N-oxide (TMAO) due to some practical reasons. The behaviour of urea and LDAO molecule was studied when these molecules were in different and same solutions. The purpose of this experiment is to find out the mechanism of LDAO against urea. Finally, LDAO interacts with urea and a possible mechanism between them is suggested. A common consequence of protein denaturation is the loss of biological activity. Natural osmolytes such as Trimethylamine N-oxide (TMAO) contribute to protein folding, whereas other osmolytes such as urea act as an agent in the denaturation of proteins. Many studies have shown that denaturation of proteins could occur for certain concentrations of urea, however, this effect could be prevented with the presence of the Trimethylamine N-oxide (TMAO) molecules. The aim of the present study is to find out the mechanism of TMAO as a protein stabilizer against urea. Firstly, Molecular Dynamics simulations were carried out for 1, 8, 27 and 64 TMAO molecules. The time-average location of TMAO molecules during the simulation was studied by the partial density. These simulations examine if TMAO is amphiphilic molecule, i.e contains both hydrophobic and hydrophilic parts. However, these results might not be representative due to bad statistics. Secondly, an experiment ran at BESSY II at Helmholtz-Zentrum Berlin using X-ray Photoelectron Spectroscopy in liquids. In this experiment, Lauryldimethylamine oxide (LDAO) was used instead of Trimethylamine N-oxide (TMAO) due to some practical reasons. The behaviour of urea and LDAO molecule was studied when these molecules were in different and same solutions. The purpose of this experiment is to find out the mechanism of LDAO against urea. Finally, LDAO interacts with urea and a possible mechanism between them is suggested. / <p></p><p></p><p></p><p></p><p></p><p></p><p></p><p></p><p></p><p></p><p></p>