Structure characterization of foams and filled polymers by means of MRI

The structure of foams and filled polymers can be analyzed by means of MRI. It is also possible to observe the deformation behavior of the structure of foams and filled polymers in situ. A displacement experiment (rigid body) was performed in the magnet and observed by MRI. The NMR images are analyzed by image processing. Average distances between particles are estimated by the use of the autocorrelation function and the spectrum of the autocorrelation function. The spectrum shows the spatial frequency of the distances. The displacement field was calculated by the cross-correlation function. Information about particle distances and micromechanical deformation can be obtained by NMR imaging methods by combining autocorrelation and cross-correlation.     

A microcalorimetric investigation of the thermodynamics of formation of the HSO4-, AlSO4+, and Al(SO4)2- ions in aqueous solutions at temperatures between 25 and 70°c

The formation constants and enthalpies of formation of the hydrogen sulfate ion anc the mono- and bisulfato complexes of aluininum(III), in aqueous solutions having ionic strengths of 1 M and temperatures ranging from 25 to 70° C, have been evaluated by microcalorimetry.     

Gauge invariance,lorentz covariance and the observer

We discuss a number of questions related to the role of the observer in classical and quantum theories of fields, in particular electrodynamics. We find the gauge-independent parts of the electromagnetic potential, which are classical observables, both in a non-covariant manner and in a Lorentz covariant, observer-dependent way. We present an analysis of the probabilistic interpretation of relativistic quantum mechanics, similar to that of the nonrelativistic theory, and discuss the gauge invariance of the corresponding probability amplitudes.     

Causal green function in relativistic quantum mechanics

The causal Green function or Feynman propagator for the free-field Klein-Gordon equation and related singular functions, defined as distributions, are related to the causal time-boundary data. Probability densities and amplitudes are defined in terms of the solutions of the Klein-Gordon equation for a complex scalar field interacting with an electromagnetic field. The convergence of the perturbation expansion of the solution of the Klein-Gordon equation for a charged scalar particle in an external field is shown for well-behaved electromagnetic potentials. Other relativistic wave equations are discussed briefly.     

Gauge-independent quantization of the schrödinger and radiation fields

The quantization of several Schrödinger fields interacting with the electromagnetic field is carried out without reference to a particular gauge. The canonical formalism requires a modification introduced by Dirac and Bergmann for constraints. The Coulomb interaction is separated from the radiation and it gives rise to bound states of atoms and molecules. Particle operators are represented in the usual manner in Fock space, while the radiation field can be described by state functionals. Constraints can be included in the canonical formalism by Lagrange multipliers, leading to results equivalent to those of Dirac and Bergmann.     

Thermofraktographie

The further development of the Thermo-Micro-Extraction, Transfer and Application Procedure (TAS) resulted in Thermofractography (TFG). The necessary apparatus for this (TASOMAT and regulating mechanisms) is desribed. In TFG a few milligrams of a sample are heated with linear rise of temperature from, e.g., 20° C–450° C. The volatile and condensable components, as well as the products of thermolysis of polymeric material, are caught continually and fractioned as the starting line of a TLC-plate. After chromatography, rapid information can thus be obtained about the components of a complex sample of mixtures which were hithertoo difficult to analyse, like e.g., chewing gum, lignins, coloured mixed textiles and fats with additives.