Wave equations onq-Minkowski space

We give a systematic account of a component approach to the algebra of forms onq-Minkowski space, introducing the corresponding exterior derivative, Hodge star operator, coderivative, Laplace-Beltrami operator and Lie-derivative. Using this (braided) differential geometry, we then give a detailed exposition of theq-d'Alembert andq-Maxwell equation and discuss some of their non-trivial properties, such as for instance, plane wave solutions. For theq-Maxwell field, we also give aq-spinor analysis of theq-field strength tensor.     

1H NMR study on the inclusion of bicyclo[3.3.1]nonanes in cyclodextrins

- and -cyclodextrins were found to form 1:1 inclusion complexes with 2,6- and 2,9-substituted bicyclo[3.3.1]nonanes. The binding constants and the structure of the complexes were estimated from titration studies and 2D ROESY experiments.     

Non-reactive metal/semiconductor interfaces: a combined AES,AFM andPAC study

Thin In films on Ge(100), Si(100) andSi(111) are investigated using Auger-electron spectroscopy (AES), atomic force microscopy (AFM) andperturbed -angular correlation (PAC) spectroscopy, respectively. The growth mode of the metal films is characterized by in situ AES measurements, indicating distinct differences between the different substrate surfaces. Additional AFM investigations are used to monitor the film topography at higher metal coverage. Finally, the local crystalline structure of the films is studied by the PAC technique.     

On spectral properties ofq-oscillator operators

The property of self-adjointness of the operatorQ =a ₊ +a _- in three types ofq-oscillator algebras is considered. Spectral measures and generalized eigenfunctions ofQ are found in the cases when this operator is bounded. Generalized eigenvectors are expressed in terms ofq-Hermite polynomials. If the operatorQ is unbounded, then its closure is not self-adjoint. However, in this case, admits self-adjoint extensions. Deficiency subspaces are one-dimensional. These subspaces are explicitly found.     

Quantum-chaotic scattering effects in semiconductor microstructures

We show that classical chaotic scattering has experimentally measurable consequences for the quantum conductance of semiconductor microstructures. These include the existence of conductance fluctuations-a sensitivity of the conductance to either Fermi energy or magnetic field-and weak-localization-a change in the average conductance upon applying a magnetic field. We develop a semiclassical theory and present numerical results for these two effects in which we model the microstructures by billiards attached to leads. We find that the difference between chaotic and regular classical scattering produces a qualitative difference in the fluctuation spectrum and weak-localization lineshape of chaotic and nonchaotic structures. While the semiclassical theory within the diagonal approximation accounts well for the weak-localization lineshape and for the spectrum of the fluctuations, we uncover a surprising failure of the semiclassical diagonal-approximation theory in describing the magnitude of these quantum transport effects.     

Determination of selenium in blood serum by ICP-OES including an on-line wet digestion and Se-hydride formation procedure

Summary An analytical procedure for the determination of Se, as well as of other trace elements of clinical interest, in undiluted blood serum samples is presented. This procedure allows the on-line wet ashing of the sample, the hydride generation and the determination of the SeH₂ formed in one step. For this purpose, carrier solution and the injected sample (300 l) were merged with an acid stream (80% H₂SO₄, 12% HClO₄, 8% HNO₃) and passed through a reaction coil heated up to 240°C. To increase the dispersion, the wet digestion was carried out in an ultrasonic field. After trapping of the gas bubbles, 5 mol/l HCl and 0.053 mol/l NaBH₄ solutions were added via T-junctions for Se-hydride generation. The nebulizing system of the ICP-OES was used as gas/liquid separator. The hydride was swept from the spray chamber into the plasma by an argon gas flow with droplets containing other sample constituents. This allows the simultaneous determination of other trace elements of clinical interest, for example Fe, Cu and Zn. The relative detection limit for Se in blood serum was 5 g/l. The quality of the developed procedure was verified in two ways: by measuring SRM Seronorm 116 and by comparing the results for different serum samples with the results obtained with ETAAS. Our results were in good agreement in both cases.Dedicated to Professor Dr. Wilhelm Fresenius on the occasion of his 80th birthday