Intrinsic Optical Dichroism in the 2d Model of Chiral Superconducting State

Recently, we have found a new intrinsic mechanism of dichroism in chiral superconductors. It relies on the existence of many orbital character of the superconducting state as in Sr₂RuO₄. Using three orbital but a two-dimensional model relevant for superconducting strontium ruthenate, we calculate temperature T and frequency ω dependent ac Hall conductivity σ _xy (ω,T) for a number of parameters. In particular, we study the changes of σ _xy due to changes in the light frequency ω, spin–orbit coupling λ and effective interaction parameters U _ij between electrons occupying in-plane d _2g orbitals. Our calculations qualitatively agree with the measured Kerr rotation angle in Sr₂RuO₄ and have a potential to describe other superconductors.     

Degradation behaviour and mechanical properties of magnesium implants in rabbit tibiae

To investigate the initial mechanical strength and the degradation behaviour with the associated changes in mechanical properties of magnesium-based osteosynthesis implants, 30 rabbits were implanted with cylindrical pins of the alloys MgCa0.8 (magnesium with 0.8 wt% calcium), LAE442 (magnesium with 4 wt% lithium, 4 wt% aluminium and 2 wt% rare earths) and WE43 (magnesium with 4 wt% yttrium and 3 wt% rare earths). The implants were inserted into the medullary cavity of both tibiae. After 3 and 6 months, each half of the animals was euthanized, respectively, and the implants were taken out. A determination of volume, three-point bending tests, scanning electron microscopy (SEM) and energy dispersive X-ray analyses as well as metallographic and μ-computed tomography examinations were accomplished. All implants were clinically well tolerated. MgCa-implants showed the least initial strength and the highest loss in volume after 6 months. SEM- and μ-computed tomography examinations revealed a pronounced pitting corrosion. Therefore, their use as degradable implant material seems to be limited. LAE442 has the best initial strength which seems to be sufficient for an application in weight-bearing bones. The degradation behaviour is very constant. However, possible unknown side effects of the rare earths have to be excluded in further investigations on biocompatibility. Considering all results of WE43, its application as osteosynthesis material for fracture repair is ineligible due to its heterogeneous and unpredictable degradation behaviour.     

Einsatz von Biocompounds zum Abbau chlorierter Kohlenwasserstoffe in der Grund- und Abwasserreinigung

Use of Biocompounds for Degradation of Chlorinated Hydrocarbons in Treatment of Ground Water and Waste Water . Process engineering approaches to waste water treatment using immobilised microorganisms (MO) permit greater biomass concentrations in the bioreactor and hence higher conversions per unit time. Moreover, the biofilms formed assure favourable conditions for degradation specialists. Immobilisation of microorganisms is feasible on both static and freely mobile supports. Use of the latter permits modification of the flow conditions in the reactor.     

Electrocrystallisation of CoFe alloys under the influence of external homogeneous magnetic fields—Properties of deposited thin films

The influence of homogeneous magnetic fields with flux density up to 1 T superimposed during the deposition of CoFe thin films on their properties has been studied. It has been clearly demonstrated that the superimposition of magnetic fields influences the resulting layer properties significantly. A pronounced impact on the layer morphology has been observed. The layers deposited under the influence of the parallel-to-electrode magnetic field appear denser and more homogenous than those obtained without a magnetic field. On the contrary, the layers deposited in the perpendicular-to-electrode magnetic field appeared more diverse. A scaling analysis revealed a smoothing effect of a parallel- and a roughening effect of a perpendicular-to-electrode magnetic field. No influence of magnetic fields neither on the deposited layers chemical composition nor the structure and texture has been found, whereas the internal stress state of the layer is affected by the superimposition. The effects are discussed with respect to the Lorentz force driven convection, which increases the electrochemical reaction's rates and improves desorption of hydrogen from the electrode surface. The alterations of magnetic properties of the CoFe thin films correlate well with the observed microstructural changes. Moreover, an in-plane magnetic anisotropy is induced by a parallel magnetic field superimposition. This phenomenon origins from a preferential next neighbour atomic pair-ordering in the direction of the magnetic field, e.g. magnetization, during deposition of the ferromagnetic alloy.     

Zero-point vibrational energy of an adsorbed film

The ground-state energy of a submonolayer⁴He film is studied, taking into account vibration perpendicular to the surface. We use an adiabatic approximation that evaluates thez motion with the surface-parallel coordinatesx, y of the atoms held fixed. The coupled atoms' dynamical equations are solved using various assumptions, all of which yield a similar result. The numerical results for the zero point energy indicate that⁴He does not form a 2D liquid at zero temperature on K, Rb, or Cs surfaces; instead it is a quantum gas.     

Synthesis of water-soluble cellulose esters applying carboxylic acid imidazolides

Water-soluble, non-ionic cellulose esters with a degree of substitution in the range from 0.11 to 3.0 were synthesized homogeneously using ionic liquids (1-butyl-3-methylimidazolium chloride, 1-ethyl-3-methylimidazolium chloride, and 1-allyl-3-methylimidazolium chloride) as reaction medium. Highly substituted 3,6,9-trioxadecanoic acid esters and 3,6-dioxaheptanoic acid esters of cellulose were obtained via the activation of the carboxylic acids with N,N’-carbonyldiimidazole. The products were characterized by the means of FTIR-, ¹H- and ¹³C NMR spectroscopy.