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Koschwitz T.,Fakultat fur Naturwissenschaften | Meinel B.,Fakultat fur Naturwissenschaften | Acker J.,Fakultat fur Naturwissenschaften
Energy Procedia

The acidic texturization using HF/HNO3/H2SiF 6 mixtures is the standard treatment of as-cut multicrystalline silicon (mc-Si) wafers to remove the saw damage and to reveal the undisturbed bulk material. Furthermore, by the texturization a certain surface morphology at the bulk silicon should be generated that leads to an enhanced light trapping by multi-reflection of the incident light within the surface. The present paper work is focused on the development of the surface morphology formed during the horizontal etching of an as-cut multicrystalline silicon wafer in a common HF/HNO3/H2SiF6 etch mixture. In a procedure of stepwise etching about 1 μm silicon was removed per etching step. After each step the same spot of the silicon surface, one on the upper side and one on the lower side, was measured by confocal microscopy. The obtained micrographs were treated with image analytical methods and line profiles and other relevant morphology sensitive parameters were extracted. It can be shown, that the resulting morphology depends on the blueprint of the microcracks under the as cut structure, and that the first microns of saw damage removal are the important steps to generate an effective texture. Furthermore, a statistically significant relationship between the reflectivity of the wafer surface and a morphology parameter was derived. © 2013 The Authors. Source

Rodiger S.,Fakultat fur Naturwissenschaften | Rodiger S.,Attomol GmbH | Lehmann W.,Attomol GmbH | Schroder C.,Fakultat fur Naturwissenschaften | And 2 more authors.

PCR is a simplistic and robust laboratory technology for nucleic acid detection. However, for research and diagnostics processing multiple targets within one reaction in an automatic fashion is a demanded feature. Combining two multiplex read out technologies, such as microarray and microbeads, the VideoScan platform was designed. This microscope imaging technology enables an automatable high throughput multiplex measurement of genetic material from biological and patient samples. © 2013 Springer-Verlag Berlin Heidelberg. Source

Bednorz C.,Free University of Berlin | Oelgeschlager K.,Free University of Berlin | Kinnemann B.,Free University of Berlin | Hartmann S.,Free University of Berlin | And 8 more authors.
International Journal of Medical Microbiology

Following the Europe-wide ban of antimicrobial growth promoters, feed supplementation with zinc has increased in livestock breeding. In addition to possible beneficial effects on animal health, feed supplementation with heavy metals is known to influence the gut microbiota and might promote the spread of antimicrobial resistance via co-selection or other mechanisms. As Escherichia coli is among the most important pathogens in pig production and often displays multi-resistant phenotypes, we set out to investigate the influence of zinc feed additives on the composition of the E. coli populations in vivo focusing on phylogenetic diversity and antimicrobial resistance.In a piglet feeding trial, E. coli were isolated from ileum and colon digesta of high dose zinc-supplemented (2500. ppm) and background dose (50. ppm) piglets (control group). The E. coli population was characterized via pulsed-field gel electrophoresis (PFGE) and multi-locus sequence typing (MLST) for the determination of the phylogenetic background. Phenotypic resistance screening via agar disk diffusion and minimum inhibitory concentration testing was followed by detection of resistance genes for selected clones.We observed a higher diversity of E. coli clones in animals supplemented with zinc compared to the background control group. The proportion of multi-resistant E. coli was significantly increased in the zinc group compared to the control group (18.6% vs. 0%).For several subclones present both in the feeding and the control group we detected up to three additional phenotypic and genotypic resistances in the subclones from the zinc feeding group. Characterization of these subclones suggests an increase in antimicrobial resistance due to influences on plasmid uptake by zinc supplementation, questioning the reasonability of zinc feed additives as a result of the ban of antimicrobial growth promoters. © 2013 Elsevier GmbH. Source

Schierack P.,Fakultat fur Naturwissenschaften | Rodiger S.,Fakultat fur Naturwissenschaften | Kuhl C.,Fakultat fur Naturwissenschaften | Hiemann R.,Fakultat fur Naturwissenschaften | And 10 more authors.

We established an automated screening method to characterize adhesion of Escherichia coli to intestinal porcine epithelial cells (IPEC-J2) and their probiotic activity against infection by enteropathogenic E. coli (EPEC). 104 intestinal E. coli isolates from domestic pigs were tested by PCR for the occurrence of virulence-associated genes, genes coding for resistances to antimicrobial agents and metals, and for phylogenetic origin by PCR. Adhesion rates and probiotic activity were examined for correlation with the presence of these genes. Finally, data were compared with those from 93 E. coli isolates from wild boars.Isolates from domestic pigs carried a broad variety of all tested genes and showed great diversity in gene patterns. Adhesions varied with a maximum of 18.3 or 24.2 mean bacteria adherence per epithelial cell after 2 or 6 hours respectively. Most isolates from domestic pigs and wild boars showed low adherence, with no correlation between adhesion/probiotic activity and E. coli genes or gene clusters. The gene sfa/foc, encoding for a subunit of F1C fimbriae did show a positive correlative association with adherence and probiotic activity; however E. coli isolates from wild boars with the sfa/foc gene showed less adhesion and probiotic activity than E. coli with the sfa/foc gene isolated from domestic pigs after 6 hour incubation.In conclusion, screening porcine E. coli for virulence associated genes genes, adhesion to intestinal epithelial cells, and probiotic activity revealed a single important adhesion factor, several probiotic candidates, and showed important differences between E. coli of domestic pigs and wild boars. © 2013 Schierack et al. Source

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