Product properties of a two-phase magneto-electric composite: Synthesis and numerical modeling

Magneto-electric (ME) materials are of high interest for a variety of advanced applications like in data storage and sensor technology. Due to the low ME coupling in natural materials, composite structures become relevant which generate the effective ME coupling as a strain-mediated product property. In this framework, it seems to be possible to achieve effective ME coefficients that can be exploited technologically. The present contribution investigates the realization of particulate ME composites with a focus on their experimental and computational characterization. We will show that different states of pre-polarizations of the ferroelectric material have a decisive influence on the overall obtainable ME coefficient. Details on the synthesis of two-phase composite microstructures consisting of a barium titanate matrix and cobalt ferrite inclusions will be discussed. Subsequently we will employ computational homogenization in order to determine the effective properties of the experimental composite numerically. We investigate the influence of different states of pre-polarization on the resulting ME-coefficients. For the numerical incorporation of the pre-polarization we use a heuristic method.     

13C- and 23Na-NMR investigations on alkali cellulose

Summary Solid state ²³Na- and ¹³C-NMR spectra of alkali cellulose are presented as a function of NaOH-concentration of the steeping lye, steeping temperature and amount of adhering lye (press factor). Results are discussed with regard to chemical binding of NaOH to the cellulose chain in the system cellulose/ NaOH/H₂O.Presented at the 22nd Microsymposium, Characterization of Structure and Dynamics of Macromolecular Systems by NMR Methods, Prague, CSSR, July 20–23,1981     

Wasserkraft in Österreich — ein traditioneller Energieträger mit Zukunft

Hydropower occupies a leading position in the energy structure in Austria. No other country in the European Union has such a high percentage of hydropower in its energy structure in proportion to other energy sources. Due to the topographic basis and the engagement of a few pioneers hydropower came into this unique position. In fact, it is the most important domestic energy source in Austria. Like no other technology hydropower has been influenced in a strong way by the values and attitudes of the Austrian society depending on the prevailing lifestyle. In addition to the technological progress the social and economical framework has changed into a liberalized and deregulated electricity market. Besides automation and the improvement in efficiency, the environmental questions are the big challenges. Unconventional innovative strategies are demanded to give and keep hydropower the importance in (energy) business it deserves, especially because of its multifunctionality and its lasting effect for the following generations.     

Health human periodontal versus peri-implant gingival tissues: an immunohistochemical differentiation of the extracellular matrix

Healthy human periodontal and peri-implant (ITI Bonefit) keratinized gingival tissues were studied immunohistochemically to evaluate the possible presence of structural differences in the extracellular matrix protein localization. Collagen types I, III, IV, and VII and fibronectin showed similar distribution in these tissues. Compared to the periodontal tissues, collagen type V was localized in higher amounts in the lamina propria of the peri-implant gingival tissues. Collagen type VI stained the periodontal tissues as a delicate microfibrillar network contrasting to the not well-stained peri-implant gingival tissues. The data show that structural differences between these tissues are present. The structural differences may be responsible for the defense of peri-implant keratinized gingival connective tissues to bacterial penetration, because of the high amount of the collagen type V component, which is responsible for the higher collagenase stability.     

Hydrogen sorption performance of pure magnesium during continued cycling

Preliminary investigations of the hydrogen absorption - desorption by commercially pure magnesium powder under continuous operation show little or no reduction in hydrogen capacity up to 70 cycles and high temperature exposure exceeding 1200 h. Absorption was studied at 260°–425°C and hydrogen pressures up to 2.0 MPa above equilibrium. Desorption was with a few exceptions done at 400°C at hydrogen pressures below 150 kPa. For practical application the hydrogen exchange may be limited to 75–90% of the complete metal to stoichiometric hydride reaction. A change of the macroscopic structure of the powder into a highly porous, sintered agglomerate did not reduce the hydrogen capacity or the reaction rate. Although this change in structure caused no deterioration of the cycling performance a further development may not be acceptable. For observation over a much larger number of cyclings a fully automated, triple line cycling facility permitting simultaneous testing under different conditions has been constructed.