High Temperature Corrosion Behavior of Iron Aluminide Alloys and Coatings

A multi-year effort has been focused on optimizing the long-term oxidation performance of ingot-processed (IP) and oxide-dispersion strengthened (ODS) Fe{sub 3}Al and iron aluminide-based coatings. Based on results from several composition iterations, a Hf-doped alloy (Fe-28Al-2Cr-0.05at.%Hf) has been developed with significantly better high temperature oxidation resistance than other iron aluminides. The scale adhesion is not significantly better; however, the {alpha}-Al{sub 2}O{sub 3} scale grows at a slower rate, approximately a factor of 10 less than undoped iron aluminide. The benefit of Hf is greatest at 1100-1200 C. Long-term oxidation resistance of commercially fabricated ODS Fe{sub 3}Al has been determined and compared to commercially available ODS FeCrAl. Scale spallation rates for ODS Fe{sub 3}Al are higher than for ODS FeCrAl. To complement studies of iron-aluminide weld-overlay coatings, carbon steel was coated with Fe-Al-Cr by thermal spraying. These specimens were then exposed in air at 900 and 1000 C and in air-1%SO{sub 2} at 800 C. Most likely due to an inadequate aluminum concentration in the coatings, continuous protective Al{sub 2}O{sub 3} could not be maintained and, consequently, the corrosion performance was significantly worse than what is normally observed for Fe{sub 3}Al

Ti alloy with enhanced machinability in UAT turning

Metastable β-titanium alloys such as Ti 15V 3Al 3Cr 3Sn are of great technological interest thanks to their high fatigue strength-to-density ratio. However, their high hardness and poor machinability increase machining costs. Additionally, formation of undesirable long chips increases the machining time. To address those issues, a metastable β-titanium alloy (Ti 15V 3Al 3Cr 2Zr 0.9La) with enhanced machinability was developed to produce short chips even at low cutting speeds. A hybrid ultrasonically assisted machining technique, known to reduce cutting forces, was employed in this study. Cutting force components and surface quality of the finished work-pieces were analyzed for a range of cutting speeds in comparison with those for more traditional Ti 15V 3Al 3Cr 3Sn. The novel alloy demonstrated slightly improved machining characteristics at higher cutting speeds and is now ready for industrial applications

Teacher performance evaluation: conflict, uncertainties and the search for meaning(s)

O texto que propomos parte de uma pesquisa longitudinal, realizada em Portugal entre 2008 e 2010, com professores do 1º Ciclo do Ensino Básico. Procura evidenciar os conflitos e incertezas que a avaliação do desempenho docente tem produzido e a busca de sentido(s) para esta avaliação e para o ‘ser professor/a’. A implementação de sistemas de avaliação do desempenho dos professores insere-se na procura de soluções para esta inquietação. Foi o que aconteceu em Portugal, em Janeiro de 2007, com a publicação em Diário da República do novo Estatuto da Carreira Docente e o Decreto que regulamentava a Avaliação do Desempenho Docente. As tensões emergiram entre docentes e Ministério da Educação, agudizaram-se com a tomada de consciência da problemática da avaliação do desempenho dos docentes com impacto na carreira profissional e provocaram incertezas e desmotivação face ao sentido do trabalho docente com impacto na identidade profissional dos professores.This article stems from a longitudinal research carried out with primary school teachers in Portugal between 2008 and 2010. The research sought to identify the conflicts and uncertainties, which have been caused by the evaluation of teacher performance, as well as to search for meaning(s) related to that evaluation and to ‘being a teacher’. The implementation of systems for the evaluation of teacher performance fits into the search for solutions to that concern. This is what happened in Portugal, in January 2007, when the new Statute of the Teaching Profession and the law to regulate Teacher Performance Assessment were published in Diário da República – the official government publication. Tensions arose between teachers and the Ministry of Education and they were aggravated by an awareness of how the problem of teacher performance evaluation would impact on the professional career of teachers and how it would cause uncertainties and demotivation concerning the vocation of teaching and its subsequent impact on the professional identity of teachers

Sequential analysis of global gene expression profiles in immature and in vitro matured bovine oocytes: potential molecular markers of oocyte maturation

Abstract Background Without intensive selection, the majority of bovine oocytes submitted to in vitro embryo production (IVP) fail to develop to the blastocyst stage. This is attributed partly to their maturation status and competences. Using the Affymetrix GeneChip Bovine Genome Array, global mRNA expression analysis of immature (GV) and in vitro matured (IVM) bovine oocytes was carried out to characterize the transcriptome of bovine oocytes and then use a variety of approaches to determine whether the observed transcriptional changes during IVM was real or an artifact of the techniques used during analysis. Results 8489 transcripts were detected across the two oocyte groups, of which ~25.0% (2117 transcripts) were differentially expressed (p < 0.001); corresponding to 589 over-expressed and 1528 under-expressed transcripts in the IVM oocytes compared to their immature counterparts. Over expression of transcripts by IVM oocytes is particularly interesting, therefore, a variety of approaches were employed to determine whether the observed transcriptional changes during IVM were real or an artifact of the techniques used during analysis, including the analysis of transcript abundance in oocytes in vitro matured in the presence of α-amanitin. Subsets of the differentially expressed genes were also validated by quantitative real-time PCR (qPCR) and the gene expression data was classified according to gene ontology and pathway enrichment. Numerous cell cycle linked (CDC2, CDK5, CDK8, HSPA2, MAPK14, TXNL4B), molecular transport (STX5, STX17, SEC22A, SEC22B), and differentiation (NACA) related genes were found to be among the several over-expressed transcripts in GV oocytes compared to the matured counterparts, while ANXA1, PLAU, STC1and LUM were among the over-expressed genes after oocyte maturation. Conclusion Using sequential experiments, we have shown and confirmed transcriptional changes during oocyte maturation. This dataset provides a unique reference resource for studies concerned with the molecular mechanisms controlling oocyte meiotic maturation in cattle, addresses the existing conflicting issue of transcription during meiotic maturation and contributes to the global goal of improving assisted reproductive technology

Perceiving pure evil: The influence of cognitive load and prototypical evilness on demonizing

The present research sought to investigate the psychological dynamics underlying demonizing, that is, the tendency to see others as personifications of pure evilness. Building on an integrative theoretical framework, it is hypothesized that the extent to which a perpetrator matches prototypical expectations of evilness shapes demonizing responses to offenders particularly when cognitive resources are impaired. In two experiments, participants were asked to memorize either a difficult or an easy telephone number (cognitive load vs. control), and were then asked to evaluate a perpetrator who murdered a young woman (Experiment 1) or who kidnapped a child (Experiment 2). Results revealed that the extent to which the description of the perpetrator was consistent with a prototypical evilness scheme influenced demonizing particularly under conditions of cognitive load. It is concluded that impairment of cognitive resources increases the influence of prototypical evilness on demonizin

Twenty years of stereotype threat research: A review of psychological mediators

This systematic literature review appraises critically the mediating variables of stereotype threat. A bibliographic search was conducted across electronic databases between 1995 and 2015. The search identified 45 experiments from 38 articles and 17 unique proposed mediators that were categorized into affective/subjective (n = 6), cognitive (n = 7) and motivational mechanisms (n = 4). Empirical support was accrued for mediators such as anxiety, negative thinking, and mind-wandering, which are suggested to co-opt working memory resources under stereotype threat. Other research points to the assertion that stereotype threatened individuals may be motivated to disconfirm negative stereotypes, which can have a paradoxical effect of hampering performance. However, stereotype threat appears to affect diverse social groups in different ways, with no one mediator providing unequivocal empirical support. Underpinned by the multi-threat framework, the discussion postulates that different forms of stereotype threat may be mediated by distinct mechanisms

Proteomics-Based Systems Biology Modeling of Bovine Germinal Vesicle Stage Oocyte and Cumulus Cell Interaction

BACKGROUND: Oocytes are the female gametes which establish the program of life after fertilization. Interactions between oocyte and the surrounding cumulus cells at germinal vesicle (GV) stage are considered essential for proper maturation or 'programming' of oocytes, which is crucial for normal fertilization and embryonic development. However, despite its importance, little is known about the molecular events and pathways involved in this bidirectional communication. METHODOLOGY/PRINCIPAL FINDINGS: We used differential detergent fractionation multidimensional protein identification technology (DDF-Mud PIT) on bovine GV oocyte and cumulus cells and identified 811 and 1247 proteins in GV oocyte and cumulus cells, respectively; 371 proteins were significantly differentially expressed between each cell type. Systems biology modeling, which included Gene Ontology (GO) and canonical genetic pathway analysis, showed that cumulus cells have higher expression of proteins involved in cell communication, generation of precursor metabolites and energy, as well as transport than GV oocytes. Our data also suggests a hypothesis that oocytes may depend on the presence of cumulus cells to generate specific cellular signals to coordinate their growth and maturation. CONCLUSIONS/SIGNIFICANCE: Systems biology modeling of bovine oocytes and cumulus cells in the context of GO and protein interaction networks identified the signaling pathways associated with the proteins involved in cell-to-cell signaling biological process that may have implications in oocyte competence and maturation. This first comprehensive systems biology modeling of bovine oocytes and cumulus cell proteomes not only provides a foundation for signaling and cell physiology at the GV stage of oocyte development, but are also valuable for comparative studies of other stages of oocyte development at the molecular level

Oxidation and oxygen diffusion in Ti-6al-4V alloy: improving measurements during sims analysis by rotating the sample

Titanium alloys are attractive to the industrial world, as they offer the benefits of low density, great corrosion resistance, and relatively good strength, making them viable candidates for a multitude of applications. However, above 500 °C, oxidation and oxygen diffusion in titanium alloys need to be taken into account as they change their microstructure and then their mechanical properties. Oxidations were carried out between 600 and 750 °C on a specific titanium alloy: an a-b annealed Ti-6Al-4V. Oxidation kinetics and oxygen diffusion in the matrix were studied. SIMS analyses were realized on rotating specimens of this two-phase polycrystalline alloy in order to reduce roughness. Composition profiles along the sample thickness were compared to microhardness measurements. SIMS mappings were realized on the smooth slopes of the crater