Angaben zur chemischen Zusammensetzung der wichtigeren ungarischen Pflaumensorten

Ohne Zusammenfassung     

Utilization of Hemicelluloses as Example for Holistic Recovery of Agricultural Residues

The objective of this work was to separate and characterize the hemicellulose from agricultural residues of annual plants and to achieve a suitable application for it. Therefore, different treatments for producing pulp were tested and compared. Wheat straw and oat husks were digested by alkaline pulping and delignification. Pectin from sugar beet pulp was obtained by acid extraction. Beside the production of pulp, the separation and utilization of hemicellulose as resource was a key aspect of this work. The hemicelluloses were tested as paper additives, flame retardants and flotation agents.     

Glasses as engineering materials: A review

Glass products have applications in design engineering, and they can solve many special problems. These materials can work in situations in which plastics and metals would fail and need to be part of designer’s repertoire. In some situations, by using these materials, some difficult problems would be solved. This paper contains a number of chapters as follows: a brief about ceramics family, a short history of glass, a brief about physics and the technology of glass fabrication, recently developed glasses with special destinations, testing methods and news about glass parts processing (grinding, waterjet processing, laser cutting, nanoimprint lithography, etc.). The last chapter of this review paper contain some strategic lines of glass usage in industry and estimations about the future of glass development.     

Spray pyrolysis of barrier layers for flexible thin film solar cells on steel

Thin film chalcopyrite solar cells grown on light-weight, flexible substrates are an appealing product. An insulating barrier layer is a requisite for flexible steel substrates to protect the chalcopyrite absorber layer from in-diffusion of iron and also to isolate the solar module, electrically, from the metal substrate. Spray pyrolysis is presented here as a means to deposit an aluminium oxide barrier layer. Optimised spray deposition conditions are investigated and subsequent solar cell results are presented. Resistivity measurements in conjunction with thermography allow assessment of the barrier layer’s insulating properties and occurrence of pin-holes in the layer. Resulting Cu(In,Ga)Se₂ cells, with a barrier layer, reach an efficiency of 14.4%.     

Approach to Obtain Electrospun Hydrophilic Fibers and Prevent Fiber Necking

Solution electrospinning of a blend containing a hydrophobic polymer with a hydrophilic functional polymer as an additive is a simple and straight‐forward route to obtain functional and hydrophilic fibers accompanied by the mechanical properties of the hydrophobic polymer. However, this process of thermodynamically unfavored surface segregation of the hydrophilic additive is not well understood. To understand the process the dependencies of the surface hydrophilization on type of hydrophilic polymers, the solvent, and the process, using poly(caprolactone) (PCL) as the matrix polymer is explored. The results show that hydrophilic fibers can be obtained using different additive hydrophilic polymers. The combination of polymer blends which show this effect can be predicted using the Flory–Huggins interaction parameter. In addition mechanical and micromechanical properties of PCL fibers blended with NCO‐terminated star‐shaped poly(ethylene glycol) (sPEG‐NCO) as additive are investigated. In this context blending with sPEG‐NCO turns out to be a powerful tool to prevent fiber necking rendering this method an interesting candidate for tissue engineering application, where it is mandatory to retain the surface properties under mechanical stress.     

Electrochemistry with alkyl-linked oligothiophenes

Two pairs of β,β′-didodecyl substituted quinquethiophenes linked via a tri- (3) and tetramethylene spacer (4) at their α-positions have been synthesized and their electrochemical behavior investigated with cyclic voltammetry in solution and in solid films. Both compounds can be charged to a tetracation in two two-electron transfer steps, which are reversible at room temperature but become partially irreversible at low temperatures. Concentration and scan rate dependent measurements support an intramolecular coupling of the oligothiophene units preferentially next to their bridging site with σ-bond formation. In solution no electropolymerization can be observed. In the solid state upon oxidation intermolecular coupling of the oligothiophene segments takes place. Conductance measurements confirm the voltammetric findings. Obviously, the mechanism of conductance is based on hopping processes within mixed valence states.