The study of microstructure of Bi,Pb-Sr-Ca-Cu-O superconductors prepared by multiple intermediate processing

The influence of a multistep intermediate pressing and sintering process on microstructure and the relation between microstructure and values of critical current density, J _c, in Bi, Pb-Sr-Ca-Cu-O high-T _c polycrystalline superconductors was studied. The J _c values increased with increasing number of pressing and sintering steps, n, only up to a certain value of n. The increase of J _c was reached by improvement of connections between grains due to compacting and by the alignment of superconducting grains in the c-axis direction. The maximal value of J _c was found for n = 5. The crack development is responsible for decreasing J _c for a higher number of steps.     

Innovation,creative destruction and structural change: firm-level evidence from European countries

The shift of employment from lower to higher productive firms is an important driver for structural change and industry dynamics. We investigate this reallocation in terms of employment gains and losses from innovation. New employment created by product innovation may be offset by employment losses in related products, known as ‘cannibalisation’ or ‘business stealing’ effects in the literature, by employment losses from process and organisational innovation and by general productivity increases. The paper investigates this effect empirically with a large data set from the European Community Innovation Survey. We find that employment gains and losses increase with technology intensity of the sector. High-technology manufacturing shows the strongest employment gains and losses from innovation, followed by knowledge-intensive services, low-technology manufacturing and less knowledge-intensive services. The net contribution of innovation to employment growth is mostly positive, an exception being manufacturing industries in recession periods.     

Common browsing and retrieval of technical and experimental data for steady state experiments

Steady state experiments like Wendelstein 7-X have to deal with large amounts of data of different kind. Discharge lengths may last from less than a second up to 30 min. During this time diagnostics will measure data in different discharge phases with different rates depending on the physical program. Furthermore the technical configuration of all devices must be logged during the discharge as well as between experiment phases. This is necessary to allow supervision of constantly running devices. All measured data must be stored together in a common database to make it easily accessible and reduce the effort to combine data. Because of these requirements a continuous data acquisition system must be provided where data may exist at any time. Intelligent methods for browsing and retrieval of the acquired data from the common database are desired. This includes calendar-based time interval selection, overview plots for intervals that cover several days and online views of the last stored data. The contribution will explain the challenges and the advantages induced by this kind of data access methods. Existing and planned solutions for Wendelstein 7-X will be depicted. Particularly the “Data Browser” – a graphical tool specially designed to fulfil these tasks at W7-X – will be presented.     

Effect of filler dispersion on the electrical conductivity and mechanical properties of carbon/polypropylene composites

Conducting carbon/polypropylene composites containing a mixed filler of crystalline natural graphite powder, carbon black, and multiwalled carbon nanotubes have been prepared. The effect of the filler dispersion on the electrical conductivity and mechanical properties has been studied. Keeping the graphite content constant and increasing the ratio of carbon black to nanotubes, the conductivity and the flexural modulus increased linearly at different graphite contents. Graphite aggregates on the cross sections were analyzed by optical microscopy to characterize the dispersion of graphite. The results of the optical microscopy studies showed that the dispersion of graphite is affected by the composition and amount of the nanofiller system. Based on the observations simplified morphological models were set up, that allowed to explain the change in the electrical and mechanical properties of the composites of different compositions. POLYM. COMPOS., 34:1195–1203, 2013. © 2013 Society of Plastics Engineers     

Flavan‐3‐ol C‐glycosides – Preparation and model experiments mimicking their human intestinal transit

In order to study the human intestinal transit of flavan‐3‐ol C‐glycosides, several C‐glycosyl derivatives were prepared by non‐enzymatic reaction of (+)‐catechin with α‐D ‐glucose, α‐D ‐galactose and α‐D ‐rhamnose, respectively. In contrast to literature data, we propose that the reaction mechanism proceeds in analogy to the rearrangement of flavan‐3‐ols during epimerization under alkaline conditions. Four of the 12 synthesized flavan‐3‐ol C‐glycosides were incubated under aerobic conditions at 37°C using saliva (2 min) and simulated gastric juice (3 h). To simulate human intestine, the C‐glycosides were also incubated under anaerobic conditions at 37°C both in human ileostomy fluid (10 h) and colostomy fluid (24 h), respectively. The flavan‐3‐ol C‐glycosides under study, i.e. (+)‐epicatechin 8‐C‐β‐D ‐glucopyranoside (1a), (+)‐epicatechin 6‐C‐β‐D ‐glucopyranoside (1d), (+)‐catechin 6‐C‐β‐D ‐galactopyranoside (2b), (+)‐catechin 6‐C‐β‐D ‐rhamnopyranoside (3b) were analyzed in the incubation samples by HPLC‐DAD and HPLC‐DAD‐MS/MS. They were found to be stable in the course of incubation in saliva, simulated gastric juice and ileostomy fluid and underwent degradation in colostomy fluid. While the 6‐C‐β‐D ‐glucopyranoside 1d was completely metabolized between 2 and 4 h, decomposition of the 6‐C‐β‐D ‐galactopyranoside 2b reached only 16±2% within 4 h of incubation. Linear degradation rates of 1d and 2b in colostomy fluid differed significantly. As microbial metabolism of flavan‐3‐ols is known not to be influenced by the stereochemistry of the aglycon, varying degradation rates are ascribed to the effect of the sugar moiety. Based on these results we assume that flavan‐3‐ol C‐glycosides pass through the upper gastrointestinal tract (oral cavity, stomach and small intestine) unmodified and are then metabolized by the colonic microflora.     

Nonenzymatic ligation of DNA with a reversible step and a final linkage that can be used in PCR

Nonenzymatic DNA ligation chemistries containing a reversible step allow thermodynamic control of product formation, but they are not necessarily compatible with polymerase enzymes. We report a ligation system that uses commercially available reagents, includes a reversible step, and results in a linkage that can function as a template for PCR amplification with accurate sequence transfer.     

The differential specificity of chymotrypsin A and B is determined by amino acid 226

The A and B isoforms of the pancreatic serine proteinase, chymotrypsin are known to cleave substrates selectively at peptide bonds formed by some hydrophobic residues, like tryptophan, phenylalanine and tyrosine. We found, however, that the B forms of native bovine and recombinant rat chymotrypsins are two orders of magnitude less active on the tryptophanyl than on the phenylalanyl or tyrosyl substrates, while bovine chymotrypsin A cleaves all these substrates with comparable catalytic efficiency. Analysing the structure of substrate binding pocket of chymotrypsin A prompted us to perform an Ala226Gly substitution in rat chymotrypsin B. The specificity profile of the Ala226Gly rat chymotrypsin B became similar to that of bovine chymotrypsin A suggesting that only the amino acid at sequence position 226 is responsible for the differential specificities of chymotrypsin A and B isoenzymes.     

Lead poisoning caused by lead-glazed ceramic household article, initially assumed to be of occupational origin

The authors observed serious lead intoxication of a 18 year old female ceramic apprentice caused by tea with lemon stored in a glazed ceramic teapot made by the patient herself. The case history suggests: 1. the need of warning people to avoid the use of ceramic tablewares made by insufficient technology for alimentary purposes. 2. Patient with lead exposure can have also alimentary intoxication. 3. It seems advisable to perform screening tests of the ceramic apprentices who use lead glazes in order to detect the eventual increased absorption of lead in time.