On the maximum damping performance of piezoelectric switching techniques

Synchronized switch damping on inductor offers a high damping performance in a broad frequency range. It consists of an inductor and resistor in a serial configuration, which are connected and disconnected from the piezoceramics in an alternating manner by a switch. When the switch is triggered by the vibration itself, it adapts to different excitation frequencies especially in the low frequency range. This article presents a detailed study of the damping performance of the synchronized switch damping on inductor technique. Calculations are performed in a normalized way. The optimal tuning of synchronized switch damping on inductor network parameters is derived, and the corresponding maximum damping performance is obtained. The results are further compared to standard linear inductance-resistance networks. For a validation of the theoretical results, measurements on a clamped beam test rig are performed. Therefore, the synchronized switch damping on inductor circuit is realized as a synthetic impedance in a DSpace environment. The measurement results are in good agreement with the theoretical calculations. © The Author(s) 2012

A new solution for the determination of the generalized couplingcoefficient for piezoelectric systems

Recently, novel damping devices based on shunted piezoceramics have been investigated. Piezoceramics are therefore embedded into the mechanical structure and convert some part of the kinetic vibration energy into electrical energy. Subsequently, this energy is dissipated in the electrical network that is connected at the electrodes of the piezoceramics. The network is designed with the aim to maximize the dissipation, which results in a damping effect on the mechanical system. Alternatively, the converted energy can be stored and utilized to power electronic devices like sensors for health monitoring, called Energy Harvesting. In both cases, the converted energy and the damping performance depend on the so called generalized electromechanical coupling coefficient K. It is therefore crucial to maximize this factor. Besider the piezoelectric material properties, the coupling coefficient also depends on the vibration mode of the piezoceramics. Only for a constant mechanical strain distribution in the whole volume the generalized coupling coefficient K is equal to the material coupling k. In all other cases, K is smaller than k. This publication presents a general derivation of the generalized coupling coefficient K for an arbitrary, uniaxial deformation of the piezoceramics, which is based on the potential energy stored in the piezoceramics. The general result is applied to a piezoelectric bending bimorph and verified by a finite element model

Assessment of a novel multiplex real-time PCR assay for the detection of the CBPP agent Mycoplasma mycoides subsp. mycoides SC through experimental infection in cattle

Mycoplasma mycoides subsp. mycoides SC is the pathogenic agent of contagious bovine pleuropneumonia (CBPP), the most important disease of cattle in Africa causing significant economic losses. The re-emergence of CBPP in Europe in the 1980s and 1990s illustrates that it is still a threat also to countries that have successfully eradicated the disease in the past. Nowadays, probe-based real-time PCR techniques are among the most advanced tools for a reliable identification and a sensitive detection of many pathogens, but only few protocols have been published so far for CBPP diagnosis. Therefore we developed a novel TaqMan®-based real-time PCR assay comprising the amplification of two independent targets (MSC_0136 and MSC_1046) and an internal exogenous amplification control in a multiplex reaction and evaluated its diagnostic performance with clinical samples

Norvaline is accumulated after a down-shift of oxygen in Escherichia coli W3110

<p>Abstract</p> <p>Background</p> <p>Norvaline is an unusual non-proteinogenic branched-chain amino acid which has been of interest especially during the early enzymological studies on regulatory mutants of the branched-chain amino acid pathway in <it>Serratia marcescens</it>. Only recently norvaline and other modified amino acids of the branched-chain amino acid synthesis pathway got attention again when they were found to be incorporated in minor amounts in heterologous proteins with a high leucine or methionine content. Earlier experiments have convincingly shown that norvaline and norleucine are formed from pyruvate being an alternative substrate of α-isopropylmalate synthase, however so far norvaline accumulation was not shown to occur in non-recombinant strains of <it>E. coli</it>.</p> <p>Results</p> <p>Here we show that oxygen limitation causes norvaline accumulation in <it>E. coli </it>K-12 W3110 during grow in glucose-based mineral salt medium. Norvaline accumulates immediately after a shift to oxygen limitation at high glucose concentration. On the contrary free norvaline is not accumulated in <it>E. coli </it>W3110 in aerobic cultures. The analysis of medium components, supported by transcriptomic studies proposes a purely metabolic overflow mechanism from pyruvate into the branched chain amino acid synthesis pathway, which is further supported by the significant accumulation of pyruvate after the oxygen downshift. The results indicate overflow metabolism from pyruvate as necessary and sufficient, but deregulation of the branched chain amino acid pathway may be an additional modulating parameter.</p> <p>Conclusion</p> <p>Norvaline synthesis has been so far mainly related to an imbalance of the synthesis of the branched chain amino acids under conditions were pyruvate level is high. Here we show that simply a downshift of oxygen is sufficient to cause norvaline accumulation at a high glucose concentration as a consequence of the accumulation of pyruvate and its direct chain elongation over α-ketobutyrate and α-ketovalerate.</p> <p>Although the flux to norvaline is low, millimolar concentrations are accumulated in the cultivation broth, which is far above the level which has been discussed for being relevant for misincorporation of norvaline into recombinant proteins. Therefore we believe that our finding is relevant for recombinant protein production but also may even have implications for the physiology of <it>E. coli </it>under oxygen limitation in general.</p

Genetic variants in eleven central and peripheral chemoreceptor genes in sudden infant death syndrome

Background: Sudden infant death syndrome (SIDS) is still one of the leading causes of postnatal infant death in developed countries. The occurrence of SIDS is described by a multifactorial etiology that involves the respiratory control system including chemoreception. It is still unclear whether genetic variants in genes involved in respiratory chemoreception might play a role in SIDS. Methods: The exome data of 155 SIDS cases were screened for variants within 11 genes described in chemoreception. Pathogenicity of variants was assigned based on the assessment of variant types and in silico protein predictions according to the current recommendations of the American College of Medical Genetics and Genomics. Results: Potential pathogenic variants in genes encoding proteins involved in respiratory chemoreception could be identified in 5 (3%) SIDS cases. Two of the variants (R137S/A188S) were found in the KNCJ16 gene, which encodes for the potassium channel Kir5.1, presumably involved in central chemoreception. Electrophysiologic analysis of these KCNJ16 variants revealed a loss-of-function for the R137S variant but no obvious impairment for the A188S variant. Conclusions: Genetic variants in genes involved in respiratory chemoreception may be a risk factor in a fraction of SIDS cases and may thereby contribute to the multifactorial etiology of SIDS. Impact: What is the key message of your article? Gene variants encoding proteins involved in respiratory chemoreception may play a role in a minority of SIDS cases. What does it add to the existing literature? Although impaired respiratory chemoreception has been suggested as an important risk factor for SIDS, genetic variants in single genes seem to play a minor role. What is the impact? This study supports previous findings, which indicate that genetic variants in single genes involved in respiratory control do not have a dominant role in SIDS

Spectroscopic study of the magnetic ground state of Nb1−y_{1-y}Fe2+y_{2+y}

We have investigated single crystals and polycrystals from the series Nb$_{1-y}$Fe$_{2+y}$, $-0.004 \leq y \leq 0.018$ by electron spin resonance, muon spin relaxation and M\"ossbauer spectroscopy. Our data establish that at lowest temperatures all samples exhibit bulk magnetic order. Slight Fe-excess induces low-moment ferromagnetism, consistent with bulk magnetometry ($\simeq 0.06 ~\mu_B/{\rm Fe}$), Nb--rich and stoichiometric NbFe$_2$ display spin density wave order with small magnetic moment amplitudes of the order $\sim 0.001 - 0.01 ~\mu_B/{\rm Fe}$. This provides microscopic evidence for a modulated magnetic state on the border of ferromagnetism in NbFe$_2$.Comment: 7 pages, 9 figure

Comparative in silico genome analysis of Clostridium perfringens unravels stable phylogroups with different genome characteristics and pathogenic potential

Clostridium perfringens causes a plethora of devastating infections, with toxin production being the underlying mechanism of pathogenicity in various hosts. Genomic analyses of 206 public-available C. perfringens strains ' sequence data identified a substantial degree of genomic variability in respect to episome content, chromosome size and mobile elements. However, the position and order of the local collinear blocks on the chromosome showed a considerable degree of preservation. The strains were divided into five stable phylogroups (I-V). Phylogroup I contained human food poisoning strains with chromosomal enterotoxin (cpe) and a Darmbrand strain characterized by a high frequency of mobile elements, a relatively small genome size and a marked loss of chromosomal genes, including loss of genes encoding virulence traits. These features might correspond to the adaptation of these strains to a particular habitat, causing human foodborne illnesses. This contrasts strains that belong to phylogroup II where the genome size points to the acquisition of genetic material. Most strains of phylogroup II have been isolated from enteric lesions in horses and dogs. Phylogroups III, IV and V are heterogeneous groups containing a variety of different strains, with phylogroup III being the most abundant (65.5%). In conclusion, C. perfringens displays five stable phylogroups reflecting different disease involvements, prompting further studies on the evolution of this highly important pathogen

Genomic insight into Campylobacter jejuni isolated from commercial turkey flocks in Germany using whole-genome sequencing analysis

Campylobacter (C.) jejuni is a zoonotic bacterium of public health significance. The present investigation was designed to assess the epidemiology and genetic heterogeneity of C. jejuni recovered from commercial turkey farms in Germany using whole-genome sequencing. The Illumina MiSeq® technology was used to sequence 66 C. jejuni isolates obtained between 2010 and 2011 from commercial meat turkey flocks located in ten German federal states. Phenotypic antimicrobial resistance was determined. Phylogeny, resistome, plasmidome and virulome profiles were analyzed using whole-genome sequencing data. Genetic resistance markers were identified with bioinformatics tools (AMRFinder, ResFinder, NCBI and ABRicate) and compared with the phenotypic antimicrobial resistance. The isolates were assigned to 28 different sequence types and 11 clonal complexes. The average pairwise single nucleotide-polymorphisms distance of 14,585 SNPs (range: 0–26,540 SNPs) revealed a high genetic distinction between the isolates. Thirteen virulence-associated genes were identified in C. jejuni isolates. Most of the isolates harbored the genes flaA (83.3%) and flaB (78.8%). The wlaN gene associated with the Guillain–Barré syndrome was detected in nine (13.6%) isolates. The genes for resistance to ampicillin (blaOXA), tetracycline [tet(O)], neomycin [aph(3')-IIIa], streptomycin (aadE) and streptothricin (sat4) were detected in isolated C. jejuni using WGS. A gene cluster comprising the genes sat4, aph(3′)-IIIa and aadE was present in six isolates. The single point mutation T86I in the housekeeping gene gyrA conferring resistance to quinolones was retrieved in 93.6% of phenotypically fluoroquinolone-resistant isolates. Five phenotypically erythromycin-susceptible isolates carried the mutation A103V in the gene for the ribosomal protein L22 inferring macrolide resistance. An assortment of 13 β-lactam resistance genes (blaOXA variants) was detected in 58 C. jejuni isolates. Out of 66 sequenced isolates, 28 (42.4%) carried plasmid-borne contigs. Six isolates harbored a pTet-like plasmid-borne contig which carries the tet(O) gene. This study emphasized the potential of whole-genome sequencing to ameliorate the routine surveillance of C. jejuni. Whole-genome sequencing can predict antimicrobial resistance with a high degree of accuracy. However, resistance gene databases need curation and updates to revoke inaccuracy when using WGS-based analysis pipelines for AMR detection

Building University Schools in Teacher Education Programmes

Pre-gradual teacher education involves students’ practice teaching as carried out in so-called university schools or faculty schools. The objective of this digital handbook is to provide various options of implementation of university school concepts in teacher education programmes. General ideas and specific steps comprising organization of collaboration-supporting practices, internship activities and requirements for school-based teacher educators’ competences are presented within this structure. This digital handbook is one of the outputs of Enhancing European Teacher Education through University Schools, an Erasmus+ EdUSchool project aimed to develop a common European understanding of university schools and their concepts among all stakeholders

BioOK – a Comprehensive System for Analysis and Risk Assessment of Genetically Modified Plants

Gentechnisch veränderte (GV) Pflanzen müssen im Rahmen des Zulassungsverfahrens in der EU auf ihre potentiellen Auswirkungen auf die Umwelt und die mensch­liche oder tierische Gesundheit analysiert werden. Der gegenwärtige Zulassungsprozess ist ein Konglo­merat verschiedenster Analysemethoden und extrem zeit- und kostenaufwendig. Das Anliegen von BioOK als ein multidisziplinäres wissenschaftliches Netzwerk ist die Entwicklung von maßgeschneiderten Ansätzen zur Risikoanalyse von GV Pflanzen auf der Grundlage von Ursache-Wirkungs­hypothesen mit dem Ziel des Aufbaus eines effektiven und qualifizierten Risikobewertungssystems. Die Forschungsaktivitäten von BioOK zielen auf einen Paradigmenwechsel im aktuellen Zulassungsprozess. Sie basieren auf einem modularen System, das alle Aspekte des Risikomanagements umfasst: molekulare Charakterisierung, Inhaltsstoffanalyse, agronomische Eigenschaften, Ziel- und Nichtzielorganismen, Boden und Mikroorganismen, Toxikologie, Allergenität und Überwachung nach Markt­einführung, wobei jeder Modul unterschiedliche Analysemethoden beinhaltet. Die durch BioOK angestrebte Reform des Risikobewertungsprozesses von GV Pflanzen umfasst zwei Phasen: zunächst die Optimierung der Analysemethoden selbst und dann die Etablierung eines Entscheidungsunterstützungssystems (Test Decision System – DSS), basierend auf biologischen Schwankungsbreiten (baselines), Zeigermerkmalen (indicators) und Grenzwerten (thresholds) für jede Analysemethode. BioOK hat in einer ersten Entwicklungsphase bereits optimierte Testmethoden entwickelt: Für die Inhaltsstoffanalyse wurde die Untersuchung auf substantielle Äquivalenz durch GC-MS, LC-MS und HPLC/RI Methoden vereinfacht. Ein neu eingeführtes Analyseschema zur Ermittlung potentieller Effekte von GV Pflanzen auf den Boden kombiniert ein in vitro System zur Beprobung von Rhizodepositaten von Pflanzen, die unter kontrollierten Umweltbedingen gewachsen sind, sowie die entsprechenden Bodentypen und deren Charakterisierung mit offenen und hochsensitiven molekular-chemischen Screening und Fingerprinting-Methoden. Ein neues in vitro System zur Simulation des Transports von Substanzen aus dem Darm ins Blut, das das Risiko der Aufnahme durch Mensch oder Tier zu einem frühen Zeitpunkt misst, wurde entwickelt. Um die Effektivität und Reproduzierbarkeit von Probenahmen an der Pflanze zu erhöhen, wird ein genau definiertes Probenahmeschema entwickelt. Schließlich, in Ergänzung der aktuellen Methodik zur Allgemeinen Überwachung (General Surveillance) von GV Pflanzen im Anbau, wurde eine Herangehensweise zur Abschätzung der Notwendigkeit für ein europaweites fallspezifisches (Case Specific) Monitoring beruhend auf Ursache-Wirkungsszenarien, erarbeitet. Die zweite Phase der BioOK F&amp;E-Arbeiten konzentriert sich auf die Entwicklung eines Entscheidungsunterstützungssystems (Decision Support System, DSS). Dazu wird ein computergestütztes System implementiert, in dem alle standardisierten und validierten Methoden zu einem Entscheidungsbaum mit Knotenpunkten, definiert über biologische Schwankungsbreiten und potentielle Risiken definierenden Grenzwerten für Zeigermerkmale, zusammengeführt sind. &nbsp; &nbsp;Genetically modified (GM) plants have to be analyzed for their potential impacts on the environment and on human or animal health before authorisation by the EU. The approval process currently refers to a conglomeration of diverse analytical methods and is intensive in time and costs. The intention of BioOK as a multidisciplinary scientific network is the development of tailor-made approaches for GM plants based on a cause-effect hypothesis to obtain an effective and qualified risk assessment system. The research activity of BioOK aims to renew the current approval process. It is based on a modular system covering all aspects of risk assessment: molecular characterisation, compound analysis, agronomic traits, target and non-target organisms, soil and micro organisms, toxicology, allergenicity and post-market monitoring, each module containing several test methods. The renewal of the risk assessment procedure intended by BioOK consists of two phases: first the optimization of test methods and second the establishment of a decision support system (DSS) based on baselines, indicators and thresholds developed for each of the methods. Optimized test methods have been developed mainly during the first phase: For compound analysis methods have been developed to ease the analysis of substantial equivalence of the events by GC-MS, LC-MS and HPLC/RI. A newly introduced testing scheme for the detection of potential effects of GM plants on soil combines an in-vitro system to collect rhizodeposits from plants grown under controlled environmental conditions and the correspon­ding bulk soil, and their characterisation by untargeted and highly sensitive molecular-chemical screening and fingerprinting technique. A novel in vitro system simula­ting the transport of substances from the gut into the blood that detects the risk of incorporation in human or animal at an early time point was developed. In order to increase the effectiveness and reproducibility of the sampling procedure we developed a valid defined sampling scheme. Finally, complementing the actual General Surveillance methodology, an approach for a Europe-wide case specific monitoring referring to cause-effect sce­narios was developed. The second phase concentrates on the development of a Decision Support System (DSS). A computer-based system will implement and merge all standardized methods in a decision tree system following decision rules defined by baseline and thresholds for indicators. &nbsp; &nbsp