A quantitative study of the aggregation behaviour of the cationic cyanine dye pinacyanol chloride in aqueous solution and in the presence of various organic matrices (anionic alginates, anionic Aerosol-OT and g-cyclodextrin) is presented based on UV/Visible absorption and Circular Dichroism (CD) spectroscopy. The spectral data have been analysed using derivative spectra and a program (PeakFit) to model the mixtures of different absorbing species with strongly overlapping absorption bands. The structures of the aggregates have been analysed and discussed in terms of qualitative (H- vs. J-type aggregation) and quantitative arguments based on a program (OSCI) for the calculation of oscillator and rotatory strengths assuming an exciton-like delocalisation of molecular excitations through the entire aggregate. Models for the various complexes of the dye in the presence of various organic matrices have been proposed

Latest since the early eighties destandardisation of employment became a term of wide comprehension. Especially in Germany the once predictable employment biography would have been dissolving for an occupational career with phases of unemployment and many job changes. Employment careers are seen to be more heterogeneous, former guaranteed securities would have been broken and working future would be no more predictable. By means of a longitudinal dataset on the basis of the German Socio-economic panel covering the years 1985 to 2000 this dissertation is showing that the destandardisation of work in West Germany is first beginning in the middle of the nineties. This is reflected in the increase of flexibilisation, the reduction of job stability (quantitative dimension) and the decrease of job security (qualitative dimension). These developments do not affect the collectivity of the work force. In the course of time a polarisation of social unemployment is arised along occupational classes and levels of education.

In this thesis, a 3D CMOS imager based on time-of-flight (TOF) has been developed and successfully tested. It uses an active pulsed class 1 laser operating at 910nm to illuminate a 3D scene. The scene depth is determined by measurement of the travel time of reflected pulses by employing a fast on-chip synchronous shutter. A so-called Multiple Double Short Time Integration (MDSI) enables suppression of the background illumination and correction for reflectivity variations in the scene objects. The sensor chip contains two pixel lines with each pixel containing twin photodiodes, thus the chip contains 4´64 sensors. The chip allows tow operating modes; the first is the binning mode, where the twin pixels are short-circuited (tow lines on the die) and the average signal is measured. The second mode is the high-resolution mode. In this mode the pixels operate separately (four lines on the die). The chip has been realized in 0.5mm n-well standard CMOS process. The pixel pitch is 130mm. To get a good fill factor, the readout circuitry is located at the sides of the chip.

The dissertation describes the effects of operating frequency reduction on the transmission behaviour of power cables. Strongly reduced current losses, lowered induced voltages in the sheaths and lower charging currents offer new solutions for the transmission of energy by cables. The following facts can be obtained by reduction of the operating frequency: an increase of the current carrying capacity, an enlargement of the transmission distance, lower thermal stress of the cable and better efficiency of the power transmission. The above mentioned advantages are typical for direct current transmission systems, but can now also be achieved for usual alternating current cables by reduction of the operating frequency. The positive effects of frequency reduction are represented for different types of power cables. The second part of the thesis describes the transmission behaviour for high frequencies. Travelling electromagnetic waves in power cables are strongly influenced by the frequency- dependent attenuation. For many applications in overvoltage protection the knowledge of the attenuation is very important. Especially in long cable systems the attenuation can be so high that lightning or switching voltages will be reduced to an innocuous level. Another area is the Power Line Communication (PLC) which uses the energy power grid for signal transmission in a frequency range up to 30 MHz. Here an in-depth analysis of the attenuation of the transmission line is very important. Particularly the admittance of the cable, composed of insulating and semiconducting materials, is very important for the attenuation of high frequencies. Simulation results agree well with measurements at a 20-kV-XLPE cable, if the semiconducting layers between conductor and screen are thoroughly modeled. For the calculations, the material parameters of the commonly used carbon-polyethylene-compound and conductive paper layers were measured. Measurements at a test setup show the attenuation for several plies of conducting paper layers on the inner conductor of a coaxial pipe system. The effect of different numbers of plies on the impulse rise time were investigated.

This thesis deals with regualrity questions of elliptic and parabolic systems of partial differential equations of second order. With the help of a Harnack inequality it is shown that bounded weak solutions of certain parabolic systems are Hölder continous. In the second chapter we prove regularity theorems for weak harmonic mappings in the interior and at the boundary, an important tool for these theorems are again two Harnack inequalities. The last two chapters deal with degenerate elliptic systems, for certain degenerate elliptic coefficients (e.g. in the Muckenhouptclass A2) we prove two Harnack inequalities and show with these inequalities some regularity theorems for degenerate elliptic systems.

The potassium pentafluorophenylfluoroborates were prepared by hydroxy-fluoride-substitution of fluoroorganoalkoxyboranes and -borates with potassium bifluoride. Those intermediate boranes and borates were obtained by the reaction of fluoroorganomagnesium reagents and alkoxyboranes. The introduction of one or two pentafluorophenylgroups into various alkoxyboranes is investigated to optimize the yield of potassium pentafluorophenyltrifluoroborate and bis(pentafluorophenyl)difluoroborate. Reactions of pentafluorophenylfluoroborates with the Lewis acids borontrifluoride and tris(pentafluorophenyl)borane show the Lewis acidity of pentafluorophenyldifluoroborane compared with borontrifluoride and tris(pentafluorophenyl)borane. Pentalfuorophenylfluoroborate salts reacted with iodinepentafluoride by transfer of a pentafluorophenylgroup to iodinepentafluoride. To develop an alternative method to fluorooganofluoroborates systematic investigations on the reactivity of fluoroorganoboranes to fluorides were undertaken. Potassium-1H,1H,2H,2H-perfluorooctyltrifluoroborate is prepared by the reaction of an organogrignard reagent with chlorodimethoxyborane and hydrolysis and hydoxy-fluoride-substitution of the product. Treatment of the borate wit borontrifluoride provides the corresponding difluoroborane with ponytailgroup.

The protein Myoglobin was used as matix-molecule to produce monomeric porphyrins in solution. The protein complexes of differen zinc pheophorbides and zinc protoporphyrin have been studied by UV/Vis and NMR spectroscopy. The protein stability versus unfolding and NMR results Based on quantum mechanical calculations analysis of EPR- and ENDOR-spectra of the light excited triplet state yielded identification of α-protons and methyl β-protons have been identified for the first time. The data acquired agrees well with previously published data on native reaction centers. The terminal electron acceptors, [4Fe4S] centers FA and FB in Photosystem I (PSI), have been modelled by peptides with 16 amino acid length synthezied by SPPS Fmoc strategy. Both peptides incorporated a [4Fe4S] cluster in oxidation state 2 /1 as prooven by UV/Vis, EPR and Mössbauer spectroscopy. The redoxpotential for the one electron reduction was found to be -470 mV for both modell peptides.

Temperature dependent swelling of different polymer networks was performed in the liquid and gaseous solvent water. To determine the swelling ratio in the water vapour gravimetrically, depending on the change of temperature, a new measure device was developed. Object of this thesis was, to qualify the shape of the swelling curves in the region of the boiling point. Swelling curves were analysed with the results of the statistic theory of swelling additionally. Together with the results of measurements of the same polymer networks in crystalline water, a mathematical description of the swelling curves was performed in solid, liquid and gaseous phase for the first time.

Two new optical analysis methods in the field of nanotechnology are introduced. Both methods are based on optical microscopy coupled with a digital image analysis system. The first method can be used as a low cost quality control process for nanoimprint lithography. Here, fluorescence microscopy is used in combination with a standard printable polymer labeled with a fluorescent dye. The optical detection allows for the observation of imprinted structures down to 100 nm of lateral size. The second method uses either dark field or fluorescence microscopy for analysis of the particle size distribution of dispersed nanoparticles with diameters between 100 and 1000 nm. Both methods are characterized by a high reliability and reproducibility as well as user-friendliness and quickness.

Ultrasonic imaging uses higher ultrasound frequencies and power levels to achieve better spacial resolution and image quality. Potential hazard for patients have to be evaluated on the basis of relevant acoustic parameters. Measurements of the acoustic pressure with piezoelectric hydrophones is only reliable up to 40 MHz because of minimum sensor size. This work improves a pizooptical measurement method for acoustic pressure. Acoustic pressure changes the refractive index of water. This is determined by measuring laser power, reflected at a fiber/water interface. To improve calibration uncertainty for that kind of measurement to the level of piezoelectric hydrophones (11% - 14%) was the primary goal. Therefore a piezooptic fiber hydrophone with single mode fiber and single mode light source (laser diode) is developed. The active area of the used single mode fiber type has a diameter of 5 µm. Since the fiber influences sound field propagation due to reflection and diffraction, sensitivity of the device is frequency dependent. These effects are compensated by mathmatic modelling. By calculaing the exact curve progression of the factor of reflection depending on the refractive index gradient at the fiber/water interface, calibration uncertainty is improved from 18% to below 11%. Results are validated by intercomparison with several calibarted piezoelectric hydrophones. Measurements are carried out on different ultrasound imagaing systems.