2021-(II)-Lecture: Angewandte Medizin-Technik
2018-(II)-Surface Tension in Critical Mixtures
Parameters which have been obtained from ultrasonic spectrometry, dynamic light scattering and shear viscosity are presented in Table (5.9). It is a fascinating aspect of the dynamic scaling theory of ultrasonic attenuation that, due to scaling of frequency data of different critical mixtures fall on one scaling function. However, the most curious specific system parameter is the characteristic relaxation rate amplitude Γ_0, which according to Bhattacharjee-Ferrell theory, corresponds with the mutual diffusion coefficient D and the fluctuation correlation length ξ. In Table (5.9) parameters Γ_0 and ξ_0 are listed for various binary mixtures with critical demixing point. The isobutoxyethanol-water system exhibits by far the smallest amplitude Γ_0 in the relaxation rate of order parameter fluctuations. In comparison, with the system n-pentanol-nitromethane, Γ_0 is 35 times larger. Assuming, that the life time of fluctuations τξ = Γ_0^−1, as inverse characteristic relaxation rate reflects intermolecular properties as well the geometry of considered components the strong variation of Γ_0 of various liquids can be understood. In addition, due to the Coulombic interactions, relaxation from a local nonequilibrium distribution of electrical charges into thermal equilibrium will involve extensive redistribution of ions in ionic solutions and may, therefore, proceed with a smaller relaxation rate than a molecular liquid mixture at the same reduced temperature. A quantity, which may be taken to summarize the above mentioned molecular properties, is the surface tension σ. If considering critical fluctuations, reflected by the fluctuation relaxation rate Γ_0 , to depend on the surface tension, a correlation between both quantities should exist.
2018-(I)-Critical Contribution, Dynamic Scaling and Crossover Theory
The following project deals with the dynamic scaling aspects within the framework of Bhattacharjee-Ferrell theory. Furthermore, relationships between the critical sound attenuation and the dynamic scaling function are presented. Moreover, crossover effects for binary and ternary fluids are presented.
Bhattacharjee-Ferrell scaling hypothesis - binary systems:
Critical phenomena, as all continuous phase transitions, Show universal characteristics of their thermodynamic properties, if they belong to the same universality class and if their dimension is identical. The concepts and consequences of critical slowing down have been presented in 2005-(II)-Critical Phenomena and Universality. In particular, the light scattering is well represented and described by dynamic scaling theories, resulting from the mode-coupling considerations. However, the treatment of critical ultrasonic attenuation necessitates the development of new theories in order to get an access to critical fluctuations in a sound field. Bhattacharjee and Ferrell have presented a general theory of the critical ultrasonic attenuation, based on an extension of the concept of the frequency-dependent specific heat. This conception was firstly introduced by Herzfeld and Rice in 1928.
2009-(I)-Fluorescence Change Detection of Glycopolymers during Phathogen Binding via Waveguide Technology
2008-(II)-13th. Parabolic-Flight (micro-gravitation research): The German Society of Aerospace: Electrical impedance tomography
The idea of the project, under the direction of Dr. Günther Hahn, was (with the help of "Electrical impedance tomography") to study the behavior of the lungs in micro gravitation (0~g,) (1-g), and (2-g). The experiment provided important results for research in micro gravitational environment, as well as data for human medicine on earth. The experiments were conducted aboard the Zero-G, during several parabolic flight maneuvers.
"Electrical impedance tomography (EIT) is a noninvasive type of medical imaging in which the electrical conductivity, permittivity, and impedance of a part of the body is inferred from surface electrode measurements and used to form a tomographic image of that part. Electrical conductivity varies considerably among various biological tissues (absolute EIT) or the movement of fluids and gases within tissues (difference EIT). The majority of EIT systems apply small alternating currents at a single frequency, however, some EIT systems use multiple frequencies to better differentiate between normal and suspected abnormal tissue within the same organ (multifrequency-EIT or electrical impedance spectroscopy)." wiki
Project Impressions:
2006-(I)-Critical Behavior and Crossover Effects in the Properties of Binary and Ternary Mixtures and Verification of the Dynamic Scaling Conception
Nature comprises a multitude of critical phenomena. Spontaneous symmetry breaking at the origin of the universe and gravitation collapse are spectacular examples. Critical phenomena occur at phase transitions. Theories of phase transitions use methods of catastrophe theory and also of theory of percolation which currently attract considerable attention. In order to understand critical phenomena, investigations of liquid-liquid phase transitions in binary and ternary mixtures are very instructive. Especially the understanding of the phase behavior and the critical phenomena in ternary mixtures, biophysics and membrane physics have attracted attention during the last years . The essential and most amazing feature of critical phenomena was the discovery of critical point universality indicating that the microscopic structure of fluids becomes unimportant in the vicinity of the critical point. The understanding of such phenomena is also of great importance for chemistry and chemical engineering in procedures like liquid and solid extraction, drying, absorption, distillation and many other chemical reaction processes, as well as for biology in operations like fermentation, biological filtration and syntheses. Moreover, theories of critical phenomena are substantial for many innovative applications such as supercritical extraction, enhanced oil recovery and supercritical pollution oxidation. The importance of the understanding and application of critical phenomena is demonstrated by the recently (08.28.07) provided studies performed in the International Space Station (ISS).
2005-(II)-Critical Phenomena and Universality
The fascination about critical phenomena is based on the universality of the behaviour of systems, which can be quite different in many of their properties. Theoretical models of critical behavior are based on the terms renormalization and scaling. Such a new model shall be verified by comprehensive measurement of coupled parameters of critically segregating binary fluids. In addition, binary mixtures are to be investigated whose spectra reflect both universal and individual behaviour. Of particular interest is the coupling of critical dynamics to elementary chemical processes.
The similarity of different systems can be described by universal power laws which determine the thermodynamic and transport properties close to a critical point. In order to study the critical behavior in different systems it is convenient to use the so-called reduced temperature:
When the temperature T of a system is close to its critical temperature T , some relevant parameters F follow a power law:
with x > 0. At ε → 0, that is T → T , all terms except the 1 in the brackets disappear. Therefore, F satisfies the power law:
with ϕ, denoting the critical exponent for the particular variable F.
2005-(I)-Game Theory (ger. Spieltheorie)
2004-(II)-Dynamic light scattering
In the last decades, light scattering techniques have been used with increasing effort for investigations of the physical properties of pure fluids and multicomponent fluids. The dynamic light scattering is a very powerful technique to determine the size of particles or to study critical fluctuations in multi-component fluids. According to the semi-classical theory, when light interacts with matter, the electric field of the light induces an oscillating electronic polarization in the molecules or atoms. With the aid of electromagnetic theory, statistical mechanics and hydrodynamics it is possible to gain information about the structural and dynamic properties of a sample.
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