The effect of short-term lipid infusion on liver function and biliary secretion in rats

This study was undertaken to determine the effect of various lipid emulsions on the hepato-biliary system in rats. Rats were randomly divided into six groups and infused continuously for 48 hr with either long-chain triglycerides (LCT), medium-chain triglycerides (MCT) or a mixture of MCT and LCT. One group infused with physiological saline solution served as controls. Throughout this period the rats received a fat free dietad libitum. During the last hour of lipid infusion bile was collected for determination of bile flow and composition. Subsequently, the rats were sacrificed and the morphology and lipid content of the liver determined. Only LCT lipid emulsions induced morphological changes and increased liver cholesterol content. In two rats infused with radiolabeled LCT, no labeled cholesterol was found in the liver, indicating that the excess hepatic cholesterol level may originate from enhanced cholesterol mobilization to the liver. Biliary cholesterol and phospholipid concentrations in LCT-treated rats were also elevated, as was the lithogenic index, whereas the other emulsions had no such effects. None of the emulsions affected the plasma liver function tests or bile flow. We therefore conclude that the lithogenicity of the bile in rats is directly related to the lipid components of the total parenteral nutrition and the type of triglyceride infused.     

Magnetron-sputtered cobalt-based protective coatings on ferritic steels for solid oxide fuel cell interconnect applications

Co, Co–Mn (67:33 at.%) and Co–Cu (67:33 at.%) coatings were fabricated using magnetron sputtering on two kinds of ferritic stainless steels (Crofer22APU and F17TNb) in order to form spinel protective coatings on metallic interconnects for solid oxide fuel cells. Despite the thickness unevenness at different regions, dense metallic coatings were successfully applied onto all necessary surfaces of the channelled interconnect substrates. Upon oxidation, spinel oxide coatings with very low Cr content were formed, reducing effectively the Cr release. Among the three protective coatings, Co–Cu coating showed the lowest area specific resistance (<15 mΩ cm² at 800 °C).     

Automatisierte enzymatische Bestimmung von Glucose,Maltose und Stärke auf Mikrotiterplatten

Automated Enzymatic Determination of Glucose, Maltose and Starch on Microtiter Plates. An automated enzymatic method for the determination of sugars and starch is described. The elimination of inherent methodical errors in the optical measurement of microtiter plates and the evalution of 96 raw data is done with the “LBR1993” software. Analysis is based on a 10min hydrolysis by glucoamylase at room temperature and determination of glucose with the GOD-PAP-method. A recovery of greater 99% for maize and potato starch is possible if the starch is transformed at 100°C by α-amylase to α-dextrins and converted in a second step with 8.88 g glucoamylase/g substrate to glucose. Solubilization of potato starch in 1 N sodium hydroxide at room temperature gives a recovery of 93%. Heating (60°C) in 0.5 N sodium hydroxide (AFNOR-method) is not suitable for sugar analysis and certain kinds of starch.     

Imaging and Diffraction Study of Continuous α-Fe2O3 Films on (0001)Al2O3

Continuous α-Fe₂O₃ films grown on bulk (0001)Al₂O₂ substrates by low-pressure chemical vapor deposition have been studied by transmission electron microscopy and the observations compared to those obtained from discontinuous films at an earlier stage of the growth process. Plan-view specimens revealed significant thermal stress in the continuous films, while cross-sectional specimens showed that cracking occurs in thicker films. The free surface of the film and the film/substrate interface appeared sharp and flat, apart from growth ledges and steps. Weak-beam imaging revealed a hexagonal misfit dislocation network consisting of perfect edge dislocations. Fine structure in the selected-area diffraction patterns which corroborates these observations is also discussed. The misfit network of partial dislocations previously observed in the discontinuous films was not observed for the continuous films, indicating an effect of film thickness, growth rate, or surface preparation on the Fe₂O₃/(0001)Al₂O₃ interface structure.     

Evaluation of commercial alloys as cathode current collector for metal-supported tubular solid oxide fuel cells

Ferritic stainless steels have become promising candidate materials for interconnects in tubular metal-supported solid oxide fuel cell stacks. A number of ferritic alloys containing between 18 and 26 mass% Cr and discrete changes in minor alloying elements and reactive elements were isothermally oxidized at 800 °C in air and their electrical resistance was measured with the objective of obtaining an overview of the properties relevant for applications for cathode side interconnect. The alloys containing Mn showed a (Mn,Cr)₃O₄ spinel layer on top of a Cr₂O₃ oxide. The electrical conductivity of the steels forming this kind of oxide layer was higher than the measured for only Cr₂O₃ former or oxide dispersion strengthened alloys and increased when the alloy contained Ti or Nb. Oxide scale spallation was observed for F18TNb and E-Brite, both containing Si. The influence of different cyclic oxidations was studied for the Crofer22APU steel, showing an irregular oxide growth as well as an increase in conductivity of the oxide scale formed when 12-h cycles were applied.     

Interfacial properties of (Ag + CuO) brazes used as sealing materials in SOFC stacks

Ceramic insulation layers in combination with air braze filler metals were investigated as material compositions suitable for joining the metallic components in planar solid oxide fuel cell stacks. This paper reports on a series of wetting experiments for determination of the interfacial properties of pure Ag and Ag + CuO brazes in contact with the oxides MgO, MgAl₂O₄, Al₂O₃ and the mixture MgO + MgAl₂O₄, as well as with ferritic steel at 1273 K. The long-term stability of the ceramic/Ag + CuO/steel joints after exposure for longer periods of time (1000 h) at 1073 K is also assessed. The influence on joining of CuO additions in the noble metal was investigated following two different routes. The first one involved melting of Ag + 4 wt% CuO brazes on the surface of solid substrates (ceramic, steel), and the second one involved melting of pure Ag on the substrates coated with a thin CuO_x layer. No differences in the values of the measured contact angles were observed. Furthermore, it was found that the reactions taking place at the interface braze/steel at the initial stage of brazing is extended in the case of Ag + 4 wt% CuO during the long-term exposure at envisaged operating temperature limiting the stability of the joint.