Electromagnetic Pump Made in a Hybrid Polymer-Ceramic Technology--Preliminary Results

This paper describes technology of the electromagnetic pump made in a hybrid polymer-ceramic technology. The pumping mechanism is realized with a mutual excitation between an electromagnetic coil and a neodymium magnet bonded to a flexible membrane. A PDMS （poly（dimethylsiloxane）） material was used to manufacture a membrane sufficient for the presented micropump. A fish trap construction is adapted to the ceramic technology. The bonding process of ceramics and polymer, using plasma oxidation method, is described as well. Moreover, a membrane deflection depending on magnet dimensions and applied voltage was measured.     

Interaction of sealing material mica with interconnect steel for solid oxide fuel cells application at 600 °C

In the last few years, a lot of effort has been undertaken to reduce the operation temperature of solid oxide fuel cells (SOFCs). Intermediate temperatures in the range of 600-650 °C are thought to be highly attractive due to the expected reduction of high-temperature corrosion and interdiffusion phenomena. Furthermore, each stack operated at higher temperatures has to pass this temperature range during thermal cycling. In this work, a study has been carried out to investigate the interaction between interconnect steel (DIN 1.4760) and vermiculite mica paper filled with talc at 600 °C. Mica paper has been implemented recently as a new sealing material for SOFC stacks, aiming to replace established but brittle glass ceramics. Corrosion experiments were conducted at 600 °C under dual gas atmosphere conditions as well as in air. The interconnect steel showed the formation of non-protective oxide scales in contact with mica, especially in the presence of air. The morphology of oxide scales was investigated by SEM/EDX. Possible reasons for this unexpected result are discussed. The complete encapsulation of mica by embossed and welded sheets made of FeCrAlY-steel (DIN 1.4767) as well as the pre-oxidation of interconnect steel were investigated as solutions to this problem. Pre-oxidation was found to be a promising measure to protect the interconnect steel from breakaway oxidation in contact with mica.     

Micro Ceramic Cell Analyzer (MCCA) - Preliminary results

This paper describes the preliminary results of a detection module for a Micro Ceramic Cell Analyzer (MCCA) development and fabrication process. The detector with integrated light source (electroluminescence diode) and photodetector (light-to-voltage converter) is made using Low Temperature Co-fired Ceramics (LTCC) technology. The presented device is assigned for use in fluorescence activated cell detection. Its performance is examined experimentally for two test solutions, which consist of Escherichia coli and Saccharomyces cervisiae cells. Investigated biological material is marked using the DAPI (4′, 6-diamidino-2′-phenylindole, dihydrochloride) fluorescent stain. After exposure to a 370 nm excitation light, the cells bonded with DAPI fluorescent blue (460 nm). Using the photodetector, fluorescence intensity was found to be proportional to the number of the cells in the test solutions.     

Evaluation of compatibility of thick-film PTC thermistors and LTCC structures

The electrical and microstructural characteristics of 1 kΩ/sq. thick-film thermistors with high positive temperature coefficients of resistivity, i.e. PTC 5093 (Du Pont) fired either on “green” LTCC (low temperature cofired ceramics) substrates or buried within LTCC structures, were evaluated. The active phase (ruthenium oxide) in the PTC thermistors is not present in the dried films but is formed during firing due to the decomposition of the ruthenate phase. Because of interactions between a glassy LTCC material and thermistors electrical characteristic, i.e. sheet resistivities and noise indices of thermistors fired on the surface LTCC substrates, changed from values obtained on alumina substrates. The differences in the measured electrical parameters were attributed to the interactions between the thermistor layers and the glassy LTCC substrates. The inter-diffusion of oxides, mainly PbO and Al₂O₃, was confirmed by microanalysis. In the case of buried thermistors, presumably due to the incompatibility of both materials, the structure de-laminated during firing. Cracks between the buried PTC films and the LTCC substrates as well as cracks in PTC films resulted in high sheet resistivities and high noise indices.     

Doping of Conjugated Polythiophenes with Alkyl Silanes

A strong modification of the electronic properties of solution‐processable conjugated polythiophenes by self‐assembled silane molecules is reported. Upon bulk doping with hydrolized fluoroalkyl trichlorosilane, the electrical conductivity of ultrathin polythiophene films increases by up to six orders of magnitude, reaching record values for polythiophenes: (1.1 ± 0.1) × 10³ S cm^?1 for poly(2,5‐bis(3‐tetradecylthiophen ‐2‐yl)thieno[3,2‐b]thiophene) (PBTTT) and 50 ± 20 S cm^?1 for poly(3‐hexyl)thiophene (P3HT). Interband optical absorption of the polymers in the doped state is drastically reduced, making these highly conductive films transparent in the visible range. The dopants within the porous polymer matrix are partially crosslinked via a silane self‐polymerization mechanism that makes the samples very stable in vacuum and nonpolar environments. The mechanism of SAM‐induced conductivity is believed to be based on protonic doping by the free silanol groups available within the partially crosslinked SAM network incorporated in the polythiophene structure. The SAM‐doped polythiophenes exhibit an intrinsic sensing effect: a drastic and reversible change in conductivity in response to ambient polar molecules, which is believed to be due to the interaction of the silanol groups with polar analytes. The reported electronic effects point to a new attractive route for doping conjugated polymers with potential applications in transparent conductors and molecular sensors.     

Angriff von Alkalien auf die Hochofenzustellungen aus Kohlenstoff und Graphit

Erstellung eines Modells für den Verlauf des Angriffs von Alkalien auf kohlenstoff- und graphithaltige Auskleidungen des Hochofens. Überlegung zur Steigerung ihrer Haltbarkeit.     

Modeling and Optimization of β-Galactosidase Entrapping in Polydimethylsiloxane-Modified Silica Composites

Protein entrapment has multiple applications in enzymatic hydrolysis, drug delivery, etc. Here, we report the studies that successfully utilized the Box–Behnken design to model and optimize the parameters of β-galactosidase entrapment in sol–gel-derived silica composites. We have also demonstrated the influence of polymer–polydimethylsiloxane as a composite modifying agent on the activity of entrapped enzymes. We have determined how different sol-gel process parameters influence the activity of entrapped enzymes. The highest impact on β-galactosidase activity was exerted by the water:tetramethoxysilane ratio, followed by polydimethylsiloxane content. Optimized synthesis parameters have been utilized to obtain a composite with maximum β-galactosidase activity. Performed porosity studies have shown that the addition of polydimethylsiloxane increased the pore diameter. Microscopy studies demonstrated that polydimethylsiloxane-modified composites are softer and less rough. Studies of β-galactosidase activity using the o-NPG test showed statistically significant shifts in the enzyme temperature and pH profiles compared to the soluble form. An improvement in the reusability of the enzyme and a significant increase in the thermal stability was also observed. When lactose was used, a strong correlation was observed between the substrate concentration and the type of the catalyzed reaction. Moreover, we have demonstrated that the yields and rates of both lactose hydrolysis and galactooligosaccharides formation were correlated with reaction temperature and with the presence of polydimethylsiloxane. All these findings provide the opportunity for industrial use of optimized PDMS-modified silica composites in lactose elimination from dairy products, e.g., milk or whey.     

Screening for differences in the proteolytic systems of Lactococcus, Lactobacillus and Propionibacterium

The caseinolytic, and the endo- and aminopeptidase activities of the intracellular (IC) and cell-envelope-associated (CE) fractions of selected strains of Lactococcus, Lactobacillus and Propionibacterium have been compared. With the exception of one Lactococcus strain, most of the caseinolytic activity of the three genera was located in the IC fraction, as was the case for the amino- and endopeptidases. The lactococci showed low activity on Pro-pNA and high activity on Gly-Pro-pNA, the reverse was characteristic for the propionibacteria (PAB) while lactobacilli took an intermediary position. Lactococcus lactis ssp. cremoris INF-C12 was the strain with the highest total endopeptidase activity. The experiment with phosphoramidon and a peptide inhibitor, β-casein f58–72 (β-CN f58–72), indicated differences of IC endopeptidases of lactic acid bacteria (LAB) and PAB. In contrast to the LAB endopeptidases, the PAB endopeptidases were little inhibited by β-CN f58–72, and were not affected by phosphoramidon. Lysozyme was used to produce spheroplasts from whole cells; however, the susceptibility to such treatment varied. Intracellular material, ≥97%, was easily released from the lactococci strains, for other strains additional sonication was most often necessary for ≥93% lactate dehydrogenase release.