Low-cycle fatigue of Type 347 stainless steel and Hastelloy alloy X in hydrogen gas and in air at elevated temperatures

An investigation was conducted to assess the low-cycle fatigue resistance of two alloys, Type 347 stainless steel and Hastelloy Alloy X, that were under consideration for use in nuclear-powered rocket vehicles. Constant-amplitude, strain-controlled fatigue tests were conducted under compressive strain cycling at a constant strain rate of 0.001/sec and at total axial strain ranges of 1.5, 3.0, and 5.0 %, in both laboratory-air and low-pressure hydrogen-gas environments at temperatures from 538 to 871 C. Specimens were obtained from three heats of Type 347 stainless steel bar and two heats of Hastelloy Alloy X. The tensile properties of each heat were determined at 21, 538, 649, and 760 C. The continuous cycling fatigue resistance was determined for each heat at temperatures of 538, 760, and 871 C. The Type 347 stainless steel exhibited equal or superior fatigue resistance to the Hastelloy Alloy X at all conditions of this study

Chlamydia Pneumoniae CdsL Regulates CdsN ATPase Activity, and Disruption with a Peptide Mimetic Prevents Bacterial Invasion

Chlamydiae are obligate intracellular pathogens that likely require type III secretion (T3S) to invade cells and replicate intracellularly within a cytoplasmic vacuole called an inclusion body. Chlamydia pneumoniae possess a YscL ortholog, CdsL, that has been shown to interact with the T3S ATPase (CdsN). In this report we demonstrate that CdsL down-regulates CdsN enzymatic activity in a dose-dependent manner. Using Pepscan epitope mapping we identified two separate binding domains to which CdsL binds viz. CdsN221–229 and CdsN265–270. We confirmed the binding domains using a pull-down assay and showed that GST–CdsN221–270, which encompasses these peptides, co-purified with His–CdsL. Next, we used orthology modeling based on the crystal structure of a T3S ATPase ortholog from Escherichia coli, EscN, to map the binding domains on the predicted 3D structure of CdsN. The CdsL binding domains mapped to the catalytic domain of the ATPase, one in the central channel of the ATPase hexamer and one on the outer face. Since peptide mimetics have been used to disrupt essential protein interactions of the chlamydial T3S system and inhibit T3S-mediated invasion of HeLa cells, we hypothesized that if CdsL–CdsN binding is essential for regulating T3S then a CdsN peptide mimetic could be used to potentially block T3S and chlamydial invasion. Treatment of elementary body with a CdsN peptide mimetic inhibited C. pneumoniae invasion into HeLa cells in a dose-dependent fashion. This report represents the first use of Pepscan technology to identify binding domains for specific T3S proteins viz. CdsL on the ATPase, CdsN, and demonstrates that peptide mimetics can be used as anti-virulence factors to block bacterial invasion

Narratives from the road to social justice in PETE: teacher educator perspectives

Developing teacher education programmes founded upon principles of critical pedagogy and social justice has become increasingly difficult in the current neoliberal climate of higher education. In this article, we adopt a narrative approach to illuminate some of the dilemmas which advocates of education for social justice face and to reflect upon how pedagogy for inclusion in the field of physical education (PE) teacher education (PETE) is defined and practiced. As a professional group, teacher educators seem largely hesitant to expose themselves to the researcher's gaze, which is problematic if we expect preservice teachers to engage in messy, biographical reflexivity with regard to their own teaching practice. By engaging in self- and collective biographical story sharing about ‘our’ teacher educator struggles in England and Norway, we hope that the reader can identify ‘her/his’ struggles in the narratives about power and domination, and the spaces of opportunity in between

Coordination and Engineering Support to COSMO End-to-End Operations

COSMO-SkyMed is an Earth Observation space program conducted by the Italian Space Agency (ASI) in conjunction with It-MoD. In the framework of the current programmatic phase concerning the operational management of the constellation, a set of qualified teams was introduced in order to perform technical, operational and engineering activities on the system, and tailored information flows were developed among ASI, It- MoD and Industrial staff in order to continuously guarantee the performances and the availability of the system and to identify potential enhancements and changes for the optimization of the overall cost/benefit ratio and the increase of the performances with respect to the original specification. Aim of this paper is to describe the conceived organization oriented to perform maintenance, operations and sustaining engineering activities in the frame of the operational management of the COSMO-SkyMed system, and to assess the tasks performed and the capabilities assured by the instituted teams, showing in detail the anomalies and non-conformances management process, the process assumed to keep the system performances inside the thresholds, to measure and validate the availability, effectiveness and efficiency figures of COSMO-SkyMed system, and to continuously figure out lessons learnt, trend analyses and optimization strategies. The efficiency of the conceived organization and processes in performing such activities is assessed in this paper through specific test cases and examples

New Parameters for Automatic End-to-End COSMO-SkyMed System Performances Monitoring

COSMO-SkyMed is an Earth Observation space program funded by the Italian Ministry of Research and Italian Ministry of Defence (It-MoD) and conducted by the Italian Space Agency (ASI) in conjunction with It-MoD. In the framework of the programmatic phase concerning the maintenance of the constellation in operational conditions, already in place, new parameters have been conceived in order to automatically monitor end-to-end system performances and engineering support efficiency. Aim of this paper is to describe all the parameters currently used to measure availability, effectiveness and efficiency figures of COSMO-SkyMed system, the lessons learned and optimization strategies concerning the parameters used during the development phase, with a particular focus on the new parameters recently designed and introduced to assess anomalies and non conformance management process efficiency. Methodologies, process architecture solutions, parameters detailed algorithms, test cases and validation strategy will be assessed in this paper, pointing out how the conceived frame gives the system owner the right confidence of an automatic monitoring of the end-to-end performances of the COSMO-SkyMed system