Increasing the effective interfacial area in plastic packed absorption columns.

Effective interfacial areas for gas absorption were measured at various irrigation rates for Raschig rings made of a ceramic (industrial porcelain) and of various plastics. The plastics used were polyethylene and polypropylene having very low wettabilities with water. The surface of some of the plastic packings was covered with a hydrophilic layer. The absorption of pure oxygen by a sodium sulphite solution containing cobalt catalyst was used for the measurement of effective interfacial area. It has been found that the effective interfacial area of plastic packings was about 40 per cent of that of geometrically similar ceramic packings. The effective interfacial area of the plastic packings was increased about 2·5 times by application of the hydrophilic layer. Thus, the wetted surface areas of plastic packings with hydrophilic surface and of ceramic packings are practically the same.     

Negative electrodes for nickel-cadmium accumulators: their properties as determined by impregnation procedure

Sintered negative electrodes for nickel-cadmium secondary cells were studied. Model electrodes prepared by means of three different impregnation methods were evaluated. It was demonstrated that the impregnation procedure may affect properties of active mass and the service life of electrodes in a significant way.     

Cultivar differences of total anthocyanins and anthocyanidins in red and purple-fleshed potatoes and their relation to antioxidant activity

Total anthocyanins (TAC) and individual anthocyanidins (AN) after hydrolysis were measured in 15 red and purple-fleshed potato cultivars produced in five different locations in the Czech Republic and a new cultivar Blaue St. Galler from Switzerland. It was found that TAC, expressed as cyanidin content, varied between 0.7 mg 100 g⁻¹ FW (cv. Blue Congo) and 74.3 mg 100 g⁻¹ FW (cv. Blaue Ludiano). Major differences in cultivars were found for AN relative abundance. For cv. Highland Burgundy Red a high proportion of pelargonidin (98.7%) was characteristic, whereas cv. British Columbia Blue contained almost exclusively cyanidin. Cultivars Violette and Vitelotte showed a relatively high content of malvidin. Cultivar Shetland Black differed from others with its higher content of peonidin (on average 36.7%). High petunidin abundance in the cultivars Valfi, Blue Congo, Salad Blue, Blaue St. Galler, Blaue Hindel Bank, Blaue Ludiano, Blaue Schweden, Farbe Kartoffel and Salad Red was found. TAC and AN contents highly corresponded with antioxidant activity (AA) determined with the ABTS, FRAP and DPPH assays in vitro. High AA was shown by the cultivars Vitelotte, Violette, Blaue Ludiano, Hafija, and Highland Burgundy Red. Increased height above sea level, higher annual sum of precipitation, and lower annual average temperatures caused higher AA and TAC. A high degree of hydroxylation and/or methoxylation of individual anthocyanidins could contribute in conjunction with other phenolics to high AA (peonidin, delphinidin and malvidin in the cultivars Blue Congo, Highland Burgundy Red and Shetland Black). Consequently, new red and purple-fleshed cultivars with high TAC and highly methoxylated and/or hydroxylated AN could be a promising source of favourable antioxidants in human nutrition.     

Polymer derived ceramic materials from Si,B and MoSiB filler-loaded perhydropolysilazane precursor for oxidation protection

Silica-based coating systems were developed using polymer derived ceramics (PDCs) technology. Ceramic composites on the base of a SiO₂ and SiNO matrix and homogeneously distributed Mo₅SiB₂, SiB₆, Si and B fillers were manufactured. The coating systems have low porosity and provide a high oxidation resistance up to 100 h at 800 °C and 1100 °C in air. The influence of temperature and atmosphere of pyrolysis on the polymer precursor, the volume fraction of filler materials on the chemical composition of compacts as well as their high-temperature oxidation protection was investigated.     

A new ternary phase in the system CaO–Al2O3–Cr2O3: Crystal structure and thermal expansion of CaAl2Cr2O7

Polycrystalline material of a novel phase in the system CaO–Al₂O₃–Cr₂O₃ has been obtained by solid-state reactions. Chemical analysis indicated the composition CaAl₂Cr₂O₇. Single-crystal growth of the new compound using borax as a mineralizer was successful. Diffraction experiments at ambient conditions on a crystal with composition CaAl_2.13Cr_1.87O₇ yielded the following basic crystallographic data: space group P 3, a = 7.7690(5) Å, c = 7.6463(5) Å, V = 399.68(6) ų, Z = 3. Structure determination and subsequent least-squares refinements resulted in a residual of R(|F|) = 2.3% for 1440 independent observed reflections and 113 parameters. To the best of our knowledge, the structure of CaAl_2.13Cr_1.87O₇ or CaAl₂Cr₂O₇ represents a new structure type. It belongs to the group of double layer structures where individual double layers contain octahedrally and tetrahedrally coordinated cation positions. Linkage between neighboring sheet packages is provided by additional calcium cations. Furthermore, thermal expansion has been studied in the interval between 29 and 790°C using in situ high-temperature single-crystal diffraction. No indications for a structural phase transition were observed. From the evolution of the lattice parameters the thermal expansion tensor has been obtained. A pronounced anisotropy is evident. The response of structural building units to variable temperature has been discussed.     

Effects of Radiographic Contrast Media on the Micromorphology of the Junctional Complex of Erythrocytes Visualized by Immunocytology

Effects of radiographic contrast media (RCM) application were demonstrated in vitro and in vivo where the injection of RCM into the A. axillaris of patients with coronary artery disease was followed by a significant and RCM-dependent decrease of erythrocyte velocity in downstream skin capillaries. Another study in pigs revealed that the deceleration of erythrocytes coincided with a significant reduction of the oxygen partial pressure in the myocardium—supplied by the left coronary artery—after the administration of RCM into this artery. Further reports showed RCM dependent alterations of erythrocytes like echinocyte formation and exocytosis, sequestration of actin or band 3 and the buckling of endothelial cells coinciding with a formation of interendothelial fenestrations leading to areas devoid of endothelial cells. Key to morphological alterations of erythrocytes is the membrane cytoskeleton, which is linked to the band 3 in the erythrocyte membrane via the junctional complex. Fundamental observations regarding the cell biological and biochemical aspects of the structure and function of the cell membrane and the membrane cytoskeleton of erythrocytes have been reported. This review focuses on recent results gained, e.g., by advanced confocal laser scanning microscopy of different double-stained structural elements of the erythrocyte membrane cytoskeleton.     

Polyaniline–silver composites prepared by the oxidation of aniline with silver nitrate in solutions of sulfonic acids

Aniline was oxidized with silver nitrate in aqueous solutions of sulfonic acids: camphorsulfonic, methanesulfonic, sulfamic, or toluenesulfonic acids. Polyaniline–silver composites were produced slowly in 4 weeks in good yield, except for the reaction, which took place in sulfamic acid solution, where the yield was low. Polyaniline in the emeraldine form was identified with UV–visible, FTIR, and Raman spectra. Thermogravimetric analysis was used to determine the silver content, which was close to the theoretical prediction of 68.9 wt.%. Transmission electron microscopy demonstrated the presence of silver nanoparticles of ca 50 nm average sizes as the dominating species, and hairy polyaniline nanorods having diameter 150–250 nm accompanied them. The highest conductivity of 880 S cm⁻¹ was found with the composite prepared in methanesulfonic acid solution. Its conductivity decreased with temperature increasing in the 70–315 K range, which is typical of metals such as silver. The conductivity of composites prepared in solutions of other acids was lower and increased with increasing temperature. Such dependence is typical of semiconductors, reflecting the dominating role of polyaniline in the conductivity behaviour. It is proposed that interfaces between the polyaniline matrix and dispersed silver nanoparticles play a dominating role in macroscopic level of conductivity.     

Efficient data association for view based SLAM using connected dominating sets

Loop closing in vision based SLAM applications is a difficult task. Comparing new image data with all previously acquired image data is practically impossible because of the high computational costs. Most approaches therefore compare new data with only a subset of the old data, for example by sampling the data over time or over space by using a position estimate. In this paper, we propose a more natural approach, which dynamically determines a subset of images that best describes the complete image data in the space of all previously seen images. The actual problem of finding such a subset is called the “Connected Dominating Set” (CDS) problem, which is well studied in the field of graph theory. Application on large indoor datasets results in approximately the same map using only 13% of the computational resources with respect to comparing with all previous images. Also, it outperforms other sampling approaches. The proposed method is particularly beneficial for realistic mapping scenarios including moving objects and persons, motion blur and changing light conditions.¹     

Mechanical testing of a FW panel attachment system for ITER

An objective of experiments and finite element simulations was to check the stiffness, the strength and the fatigue resistance of the attachment of the First Wall panels onto a shield block of blanket modules according to the ITER 2001 design. The panel has a poloidal key at the rear side (in so-called option A with the rear access bolting) and it is attached by means of special studs located on a key-way in the shield block. Special device for a test of stud tensile pre-load relaxation during a thermal cycling was developed. True-to-scale panels, the shield block mock-up and simplified studs were fabricated and the assembly was loaded alternatively by radial moment, poloidal force or poloidal moment simulating the loading during off-normal plasma operations. Thermal cycling led to an acceptable stud pre-load relaxation. Mechanical cycling caused neither the pre-load relaxation nor the loss of the contact in the key-way nor a damage of the attachment system. The combination of poloidal moment and radial force during vertical displacement events (VDEs) seems to be a most dangerous case because it could lead to the loss of the key–key-way contact.