Semiconductor TiO2 Gas Sensor for Controlling Nitrocarburizing Processes

TiO₂ films can serve as oxygen sensors for controlling the nitrogen potential in the process of nitrocarburizing. In contrast to conventional semiconductor-base oxygen sensors that lose stability under extreme thermal and chemical conditions in nitriding and carburizing atmospheres, TiO₂ films obtained by the sol-gel method offer a promising alternative. In the present work TiO₂ films with a density of about 80% and a grain size of 30 – 50 nm are deposited by the sol-gel technology. Steel substrates and commercial substrates from Al2O3 aluminum oxide with platinum electrodes are coated and calcinated. In order to preserve the sensitive element of the sensor a special casing is constructed for operation under conditions very close to the atmosphere of nitrocarburizing. The sensitive element consists of an Al2O3 substrate with built-in Pt-electrodes, which is coated by a thin sol-gel TiO₂ film. The direct current in the furnace is measured for nitrocarburizing in various mixtures (N₂, O₂, H₂, and NH₃) at a temperature of 500 – 600°C. A linear dependence log[R] – log[p _O2], where R is the electrical resistivity, is obtained for the films in the studied range of partial pressure of oxygen independently p _O2 of the presence of NH₃ or H₂ in the atmosphere. The dependence log[R] – log[p _O2] for a nitriding furnace with a capacity of 90 liters is shown to be stable with 3% scattering per month.     

Crime and regional economic growth in Mexico: A spatial perspective

The aim of this paper is to examine the effects of crime on regional economic growth in Mexico. We estimate a growth model using a spatial panel data model and test for the presence and type of spatial interaction, as proposed by Elhorst. Our results suggest that a two‐way spatial Durbin model best fits the data, crime exerts a negative total effect on economic growth across Mexican states, particularly homicides and robbery, and significant spillover effects seem to reinforce the negative impact on regional growth.     

Science models as value-added services for scholarly information systems

The paper introduces scholarly Information Retrieval (IR) as a further dimension that should be considered in the science modeling debate. The IR use case is seen as a validation model of the adequacy of science models in representing and predicting structure and dynamics in science. Particular conceptualizations of scholarly activity and structures in science are used as value-added search services to improve retrieval quality: a co-word model depicting the cognitive structure of a field (used for query expansion), the Bradford law of information concentration, and a model of co-authorship networks (both used for re-ranking search results). An evaluation of the retrieval quality when science model driven services are used turned out that the models proposed actually provide beneficial effects to retrieval quality. From an IR perspective, the models studied are therefore verified as expressive conceptualizations of central phenomena in science. Thus, it could be shown that the IR perspective can significantly contribute to a better understanding of scholarly structures and activities.     

Konventionelle PCR- und Real-Time PCR- Verfahren zum Nachweis von thermophilen Campylobacter jejuni, C. coli und C. lari : ein Überblick

Many PCR-techniques have already been published for the detection of thermophilic Campylobacters. In order to provide a practical overview for the user – without laying claim to completeness – we present a collection of actual PCR detection methods, some of them were modified and some are still unpublished. They are listed along with their target genes and specificities. Four conventional and seven real-time PCR methods were tested and compared using a panel of 65 Campylobacter strains belonging to 12 different more or less related species. The regular PCR methodes tested include the 16S rRNA gene based technique that specifically detects C. jejuni, C. coli and C. lari without differenciating to species level, two flaA gene based typing-methods, one for C. jejuni and C. coli in combination, which was slightly modified according to Nachamkin et al. (1993, 1996), and additionally for C. lari. Another duplex PCR was carried out which allows identification of the two species C. jejuni and C. coli simultaneously. Among the real-time methods tested there were three techniques allowing identification of C. jejuni alone, two assays based on the flagellin A gene capable to identify C. jejuni and C. coli in combination, a duplex PCR performed as triplex PCR combined with an internal amplification control that detected C. jejuni and C. coli separately, and a Lightcycler method that detected C. jejuni, C. coli and C. lari simultaneously. Inclusivity and exclusivity were shown for each of the methods. In most cases inclusivity was good, but some techniques raised problems concerning exclusivity. Flagellin based real-time PCR techniques partially crossreacted either with C. lari or C. upsaliensis. C. hyoilei which is very closely related to C. coli reacted in almost all methods applied like C. coli.

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Zusammenfassung: Eine Vielzahl von PCR-Nachweismethoden für Campylobacter jejuni und C. coli wurden bereits publiziert. Hier wird eine Zusammenfassung von aktuellen PCR-Nachweismethoden für thermophile Campylobacter spp. pr?sentiert, die dem Anwender exemplarisch eine schnelle tabellarische übersicht über aktuelle Methoden bietet sowie über deren Zielgene und Spezifit?ten. Es wurden vier konventionelle und sieben Real-Time PCR-Methoden zur Identifizierung von Campylobacter spp. verglichen. Bei den konventionellen Methoden handelt es sich um eine auf dem 16S rRNA-Gen basierende PCR, die spezifisch mit C. jejuni, C. coli und C. lari reagiert, zwei auf dem Flagellin-Gen beruhende PCR-Typisierungsmethoden, die in modifizierter Form für C. jejuni, C. coli und zus?tzlich für C. lari durchgeführt wurden. Als vierte Methode wurde eine Duplex-PCR zur Identifzierung von C. jejuni und C. coli mit einbezogen. Unter den getesteten Real-Time PCR-Methoden befanden sich drei 5′-Nuklease Assays, die spezifisch C. jejuni detektieren, zwei Assays, die auf dem Flagellin-Gen beruhen und C. jejuni und C. coli gemeinsam erfassen, eine Duplex-PCR, die C. jejuni (mapA-Gen) und C. coli (ceu-EGen) identifizieren kann und noch mit einer unver?ffentlichten internen Kontrolle kombiniert wurde, sowie eine Lightcycler-Methode, die auf dem 16S rRNA-Gen basiert und C. jejuni, C. coli und C. lari gemeinsam detektiert, aber nicht differenziert. Die Methoden sind entweder unver?ndert aus Publikationen übernommen oder auch nach Datenbankanalysen modifziert worden. Zum Testen wurden 65 Campylobacter-St?mme aus 12 verschiedenen Spezies eingesetzt. Die Inklusivit?t war insgesamt bei allen Methoden sehr gut, bei der Exklusivit?t gab es Unsicherheiten. Real-Time PCR-Methoden, die auf dem Flagellin-Gen beruhen, k?nnen in manchen F?llen die verwandten Arten C. lari oder C. upsaliensis mit erfassen. Der enge Verwandte C. hyoilei wird in fast allen F?llen gleichzeitig mit C. coli detektiert.

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Eingegangen: 31. Januar 2007     

Effects of functional electrical stimulation in denervated thigh muscles of paraplegic patients mapped with T 2 imaging

OBJECT: Functional electrical stimulation (FES) for paraplegic patients, with the long-term goal of ultimately restoring muscle function, is associated with several positive effects: improvement of blood circulation, skin condition, peripheral trophism and metabolism, prophylaxis against decubitus ulcer and better physical fitness. Since fibres of denervated muscles (lacking a supplying nerve) need to be activated directly, the fraction of elicited muscle tissue follows the geometric distribution of the electrical field, which can be simulated using electrophysiological computer models. Experimental validation of these results, however, has not yet been established. MATERIALS AND METHODS: We acquired T (2) parameter images using a multislice multi-spin-echo MR sequence before and immediately after FES in nine denervated paraplegic patients and three healthy subjects in order to visualise the geometric distribution of activation by electrically induced muscle stimulation in denervated versus innervated (healthy) thigh muscle. RESULTS AND CONCLUSION: After realigning and normalisation, maps of relative T (2) increase were calculated. The results demonstrate that the spatial distribution of short-term effects of FES of denervated muscle tissue of paraplegic patients who regularly perform FES can be visualised by T (2) parameter images. This may be used to refine models of the electrical field of FES in muscle and fibre activation in the future.     

Gefüge und mechanische Eigenschaften eines durch Sprühkompaktieren hergestellten Stahles 100Cr6

Microstructure and mechanical properties of a high strength bearing steel SAE 52100 produced by spray deposition Spray depositing allows the production of steels having a structure which is free of any macro‐segregation, homogeneous and equiaxed. Nevertheless the spray deposition of steels shows some effects that have to be regarded as disadvantages. A porous region at the billet border and a rather coarse‐grained microstructure can be noticed. As a result, in the presented work the influence of a subsequent hot rolling and a following heat treatment on microstructure and mechanical properties has been investigated. For this purpose the bearing steel SAE 52100 has been used as master material. The initial microstructure has been transformed to a homogeneous equiaxed fine‐grained pearlitic microstructure without any remaining porosity. To get use of the characteristic properties of this high‐strength steel an isothermal bainitic hardening has been carried out. Information about the mechanical properties of this material has been gained by tensile and fatigue tests. For fatigue tests in the longitudinal and cross direction of the hot rolled bars a special miniature specimen has been developed.     

Validation of a Duplex Real-Time PCR for the Detection of Salmonella spp. in Different Food Products

A 5′ nuclease duplex real-time polymerase chain reaction (PCR) assay was developed and validated with various food products for the specific and fast detection of Salmonella spp. in food. The assay used previously published primers in combination with a newly developed probe targeting the invA gene. An internal amplification control, which is coamplified in a duplex PCR, was included in the assay. The analysis of 1,934 natural food samples with real-time PCR and the cultural method in parallel resulted in a relative accuracy of 100% and 99.84% respectively, depending on the enrichment procedure in which buffered peptone water and selective enrichment in Rappaport–Vassiliadis (RV) broth were employed. The duplex real-time PCR assay has proven to be a specific, sensitive and fast screening method for Salmonella spp. in food. The overall analysis time of the PCR method was approximately 28 h, in contrast to 4 to 5 days with conventional Salmonella diagnostics. The developed assay has been shown to be a reliable diagnostic tool for use in routine analysis. It has been validated thoroughly and has become an official method in Germany for the detection of Salmonella spp. in food.     

Classification of incunable glyphs and out-of-distribution detection with joint energy-based models

Optical character recognition (OCR) has proved a powerful tool for the digital analysis of printed historical documents. However, its ability to localize and identify individual glyphs is challenged by the tremendous variety in historical type design, the physicality of the printing process, and the state of conservation. We propose to mitigate these problems by a downstream fine-tuning step that corrects for pathological and undesirable extraction results. We implement this idea by using a joint energy-based model which classifies individual glyphs and simultaneously prunes potential out-of-distribution (OOD) samples like rubrications, initials, or ligatures. During model training, we introduce specific margins in the energy spectrum that aid this separation and explore the glyph distribution’s typical set to stabilize the optimization procedure. We observe strong classification at 0.972 AUPRC across 42 lower- and uppercase glyph types on a challenging digital reproduction of Johannes Balbus’ Catholicon, matching the performance of purely discriminative methods. At the same time, we achieve OOD detection rates of 0.989 AUPRC and 0.946 AUPRC for OOD ‘clutter’ and ‘ligatures’ which substantially improves upon recently proposed OOD detection techniques. The proposed approach can be easily integrated into the postprocessing phase of current OCR to aid reproduction and shape analysis research.