The roles of Eu during the growth of eutectic Si in Al-Si alloys

Controlling the growth of eutectic Si and thereby modifying the eutectic Si from flake-like to fibrous is a key factor in improving the properties of Al-Si alloys. To date, it is generally accepted that the impurity-induced twinning (IIT) mechanism and the twin plane re-entrant edge (TPRE) mechanism as well as poisoning of the TPRE mechanism are valid under certain conditions. However, IIT, TPRE or poisoning of the TPRE mechanism cannot be used to interpret all observations. Here, we report an atomic-scale experimental and theoretical investigation on the roles of Eu during the growth of eutectic Si in Al-Si alloys. Both experimental and theoretical investigations reveal three different roles: (i) the adsorption at the intersection of Si facets, inducing IIT mechanism, (ii) the adsorption at the twin plane re-entrant edge, inducing TPRE mechanism or poisoning of the TPRE mechanism, and (iii) the segregation ahead of the growing Si twins, inducing a solute entrainment within eutectic Si. This investigation not only demonstrates a direct experimental support to the well-accepted poisoning of the TPRE and IIT mechanisms, but also provides a full picture about the roles of Eu atoms during the growth of eutectic Si, including the solute entrainment within eutectic Si

The problems of inattention: methods and interpretations. (Editorial)

Non

Conditioned blocking and schizophrenia: a replication and study of the role of symptoms, age, onset-age of psychosis and illness-duration

Introduction: Measures of selective attention processing like latent inhibition (LI) and conditioned blocking (CB) are disturbed in some patients with schizophrenia. (LI is the delay in learning about the associations of a stimulus that has been associated with no event [vs. de novo learning]; CB is the delay in learning the associations of a stimulus-component when the other component has already started to acquire these associations.) We proposed, - a) to replicate the reported decreases of CB in patients without paranoid-hallucinatory symptoms, b) to see if CB depends on the age of illness-onset and its duration, as reported for LI. Methods: We studied 101 young and old, acute and chronically ill patients with schizophrenia, of whom 62 learned a modified 'mouse-in-house' CB task, and compared them with 62 healthy controls matched for age, education and socio-economic background. Results: 1/ CB was more evident in patients with a diagnosis of paranoid schizophrenia than other subtypes. 2/ An unusual persistence of high CB scores through testing was associated with productive symptoms (including positive thought disorder). 3/ Reduced CB related to the increased expression of a) Schneider's first rank symptoms of ideas-of-reference and b) to negative symptoms like poor rapport and poor attention. 4/ CB was less evident in the older patients (age range 9.5-63.3y) and those with an earlier illness-onset (range 8.5-45.8y). Conclusions: In contrast to the similar LI test of selective attention CB is found in patients with paranoid schizophrenia and, unlike LI, the expression of CB by patients with schizophrenia is not related closely to illness-duration. Reduced CB tended to be found in those with an earlier onset, a group often noted for more severe cognitive problems. These results imply that CB and LI reflect the activity of different underlying processes. We suggest that reduced CB on the first few test-trials in nonparanoid schizophrenia reflects the unusual persistence of controlled information processing strategies that would normally become automatic during conditioning. In contrast continued CB during testing in patients with positive (paranoid) symptoms reflects an unusual persistence of automatic processing strategies

Disgust implicated in obsessive-compulsive disorder

Psychiatric classificatory systems consider obsessions and compulsions as forms of anxiety disorder. However, the neurology of diseases associated with obsessive-compulsive symptoms suggests the involvement of fronto-striatal regions likely to be involved in the mediation of the emotion of disgust, suggesting that dysfunctions of disgust should be considered alongside anxiety in the pathogenesis of obsessive-compulsive behaviours. We therefore tested recognition of facial expressions of basic emotions (including disgust) by groups of participants with obsessive-compulsive disorder (OCD) and with Gilles de la Tourette's syndrome (GTS) with and without co-present obsessive-compulsive behaviours (GTS with OCB; GTS without OCB). A group of people suffering from panic disorder and generalized anxiety were also included in the study. Both groups with obsessive-compulsive symptoms (OCD; GTS with OCB) showed impaired recognition of facial expressions of disgust. Such problems were not evident in participants with panic disorder and generalized anxiety, or for participants with GTS without obsessions or compulsions, indicating that the deficit is closely related to the presence of obsessive-compulsive symptoms. Participants with OCD were able to assign words to emotion categories without difficulty, showing that their problem with disgust is linked to a failure to recognize this emotion in others and not a comprehension or response criterion effect. Impaired recognition of disgust is consistent with the neurology of OCD and with the idea that abnormal experience of disgust may be involved in the genesis of obsessions and compulsions

Enzymatic pre-treatment of microalgae cells for enhanced extraction of proteins

Crude proteins and pigments were extracted from different microalgae strains, both marine and freshwater. The effectiveness of enzymatic pre-treatment prior to protein extraction was evaluated and compared to conventional techniques, including ultrasonication and high-pressure water extraction. Enzymatic pre-treatment was chosen as it could be carried out at mild shear conditions and does not subject the proteins to high temperatures, as with the ultrasonication approach. Using enzymatic pre-treatment, the extracted proteins yields of all tested microalgae strains were approximately 0.7 mg per mg of dry cell weight. These values were comparable to those achieved using a commercial lytic kit. Ultrasonication was not very effective for proteins extraction from Chlorella sp., and the extracted proteins yields did not exceed 0.4 mg per mg of dry cell weight. For other strains, similar yields were achieved by both treatment methods. The time-course effect of enzymatic incubation on the proteins extraction efficiency was more evident using laccase compared to lysozyme, which suggested that the former enzyme has a slower rate of cell disruption. The crude extracted proteins were fractionated using an ion exchange resin and were analyzed by the electrophoresis technique. They were further tested for their antioxidant activity, the highest of which was about 60% from Nannochloropsis sp. The total phenolic contents in the selected strains were also determined, with Chlorella sp. showing the highest content reaching 17 mg/g. Lysozyme was also found to enhance the extraction of pigments, with Chlorella sp. showing the highest pigments contents of 16.02, 4.59 and 5.22 mg/g of chlorophyll a, chlorophyll b and total carotenoids, respectively

Lignin biomarkers as tracers of mercury sources in lakes water column

This study presents the role of specific terrigenous organic compounds as important vectors of mercury (Hg) transported from watersheds to lakes of the Canadian boreal forest. In order to differentiate the autochthonous from the allochthonous organic matter (OM), lignin derived biomarker signatures [Lambda, S/V, C/V, P/(V ? S), 3,5-Bd/V and (Ad/Al)v] were used. Since lignin is exclusively produced by terrigenous plants, this approach can give a non equivocal picture of the watershed inputs to the lakes. Moreover, it allows a characterization of the source of OM and its state of degradation. The water column of six lakes from the Canadian Shield was sampled monthly between June and September 2005. Lake total dissolved Hg concentrations and Lambda were positively correlated, meaning that Hg and ligneous inputs are linked (dissolved OM r2 = 0.62, p\0.0001; particulate OM r2 = 0.76, p\0.0001). Ratios of P/(V ? S) and 3,5-Bd/V from both dissolved OM and particulate OM of the water column suggest an inverse relationship between the progressive state of pedogenesis and maturation of the OM in soil before entering the lake, and the Hg concentrations in the water column. No relation was found between Hg levels in the lakes and the watershed flora composition—angiosperm versus gymnosperm or woody versus non-woody compounds. This study has significant implications for watershed management of ecosystems since limiting fresh terrestrial OM inputs should reduce Hg inputs to the aquatic systems. This is particularly the case for largescale land-use impacts, such as deforestation, agriculture and urbanization, associated to large quantities of soil OM being transferred to aquatic systems

Eliciting and Foregrounding the Voices of Young People at Risk of School Exclusion: How Does this Change Schools’ Perceptions of Pupil Disaffection?

This thesis comprises two papers. Paper One: Previous research in relation to young people who are at risk of school exclusion can be criticised for the lack of studies that truly elicit and foreground the voices of these young people within a school context. While retrospective studies have explored their views post exclusion, few have examined their perceptions within a mainstream context prior to exclusion. This can be explained in terms of the inherent difficulties of engaging disaffected young people with research, often attributed to a combination of poor language skills and negative perceptions of adults, and schools’ reluctance to foreground these voices. This paper reports how a participatory research method, which took into account the individual needs of disaffected young people, overcame these difficulties and succeeded in eliciting the voices of ten young people at risk of school exclusion within their mainstream context. Rich, meaningful and contextualised data were generated about disaffected young people’s perceptions of their mainstream school experiences. The data were thematically analysed and then interpreted using self determination theory (Ryan & Deci, 2000). This revealed that from young people’s perspectives the need for a sense of relatedness was more relevant than the need for a sense of autonomy. The need to feel competent only became relevant in certain subject contexts. Findings showed a more holistic and nuanced perspective of disaffection. The young people perceived their engagement to be context driven and, importantly, were able to view themselves as positively engaged with some aspects of school. This highlights the need for further research into disaffected young people’s voices regarding what they perceive to be positive engagement as this may differ from practitioners’ perceptions. Implications for practice are that Educational Psychologists (EPs) are well placed to foreground the voice of disaffected young people with practitioners. In so doing they help them make better sense of disaffected young people’s school experiences and enhance practitioners’ ability to support these young people. Paper Two: Interventions in relation to young people at risk of exclusion tend to be drawn from education practitioner views which focus on a particular perspective of disaffection such as within child or curricular factors. Consequently interventions are ‘done to’ rather than ‘with’ young people and lack an integrated, holistic approach. In this small case study the researcher facilitated an intervention with seven Learning Mentors (LMs) set within two different school contexts. The aim of the intervention was to engage LMs with the voice of disaffected young people. The LMs met in two groups over two months during which vignettes of disaffected young people’s voices were used as stimuli for prioritising, implementing and evaluating changes to current LM practice. LMs’ personal constructs of disaffected young people were elicited pre and post intervention. The findings reveal that when LMs are facilitated to engage with the voice of disaffected young people it can have a positive impact on their perceptions of those young people. The effectiveness of the impact was dependent on the context of the school, level of training received and the extent to which LMs engaged with the facilitative process. As this is one of few studies which have implemented an intervention to engage schools with the voice of disaffected young people, further research exploring whether the intervention could be replicated in other school contexts would be of value. This study adds to the body of knowledge on school disaffection in young people and indicates that EPs are well placed to manage facilitative processes aimed at engaging schools with the voices of disaffected young people. In doing so they support practitioners to broaden their understanding of these young people and, importantly, enable them to act on their voices

Die kooperative Gestaltung des Übergangs zur weiterführenden Schule

Übergänge im Lebenslauf gelten als richtungsweisend für den Bildungs- und Berufserfolg und tragen damit zur Ermöglichung einer gesellschaftlichen Teilhabe bei (Tillmann, 2013). Der Übergang zur weiterführenden Schule gilt dabei als einer der bedeutsamsten, da dieser als zentrale Weichenstellung innerhalb der Bildungsbiografie von Schülerinnen und Schülern begriffen wird, welche die weiteren Qualifikationen der Schülerinnen und Schüler und in der Folge den beruflichen Erfolg beeinflusst (Berkemeyer, Bos, Manitius, Hermstein & Khalatbari, 2013; Holtappels, 2017). Darüber hinaus können große Schulleistungsstudien, wie beispielsweise die Internationale Grundschul-Lese-Untersuchung (IGLU), trotz seiner zentralen Bedeutung auch noch aktuell erhebliche Missstände an diesem Übergang konstatieren (Stubbe, Lorenz, Bos & Kasper, 2016; vgl. Wendt et al., 2016). Hieraus wird die Relevanz einer erfolgreichen Bewältigung dieses Übergangs seitens der Kinder und Jugendlichen unmittelbar deutlich, weshalb einer umfassenden Gestaltung dieses Übergangs auch seitens der Politik und der Gesellschaft eine wachsende Bedeutung zugesprochen wird (vgl. Bellenberg & Forell, 2013). Insbesondere im formalen Bildungswesen lassen sich dahingehend auch bereits vermehrt verschiedene Programme und Initiativen ausmachen, die sich der Gestaltung der verschiedenen institutionellen Bildungsübergänge im Lebenslauf widmen, um Angebote im Sinne einer nahtlosen Bildungsbiografie des Einzelnen aufeinander abzustimmen (Brandel, Gottwald & Oehme, 2010). Hierfür wird im Rahmen des Aufbaus von Bildungslandschaften eine Zusammenarbeit von allen an Bildung beteiligten Akteuren aus unterschiedlichen Kontexten fokussiert, sodass die einzelnen Übergänge möglichst ganzheitlich bearbeitet werden können (ebd.). In der Folge kann angenommen werden, dass neben den einzelnen Akteuren auch unterschiedliche Systeme, wie etwa Schulen, Kindertagesstätten oder kommunale Koordinierungsstellen, zur Gestaltung dieser Übergänge aufeinandertreffen. Es ist ferner anzunehmen, dass diese Akteure den Übergang entlang ihrer eigenen Systemlogik gestalten, was zu möglichen Kommunikationsschwierigkeiten zwischen den Systemen führen kann und somit die geforderte Kooperation der Systeme hinsichtlich der Übergangsgestaltung erschwert. Von diesen Überlegungen ausgehend soll am Beispiel der Gestaltung des Übergangs zur weiterführenden Schule unter Zuhilfenahme systemtheoretischer Ansätze die Kommunikation zwischen verschiedenen Systemen analysiert werden. Übergreifend lässt sich die Arbeit dabei in zwei Teile gliedern. Im ersten Teil geht es zunächst darum, in den aktuellen Diskurs zum Lebenslangen Lernen und den damit verbunden Auf- bzw. Ausbau der Bildungslandschaften einzuführen, wobei hier vor allem die kommunale Gestaltung des Übergangs von der Grundschule zur weiterführenden Schule fokussiert wird. Hierbei wird neben einem kurzen Überblick über aktuelle Herausforderungen an diesem Übergang ein theoretisches Rahmenmodell von van Ophuysen und Harazd (2014) vorgestellt, das den Übergang von der Grundschule zur weiterführenden Schule aus einer Schulqualitätsperspektive fokussiert und das, der Idee des Auf- und Ausbaus von Schul- und Bildungslandschaften folgend, Kooperationen für die Gestaltung dieses Übergangs auf unterschiedlichen Ebenen voraussetzt. Einige von den in diesem Modell theoretisch angenommen Bausteinen werden sodann anhand weiterer Forschungsarbeiten, die den Kumulus dieser Arbeit bilden, empirisch abgesichert. Danach werden weitere Implikationen für das Modell herausgearbeitet. Im zweiten Teil der Arbeit wird dann zunächst ein Überblick über systemtheoretische Grundlagen gegeben, bevor die Charakteristika der für diese Arbeit relevanten Systeme dargestellt werden. Entlang des eingeführten Modells von van Ophuysen und Harazd (2014) werden in einem weiteren Schritt am Beispiel des Übergangs von der Grundschule zur weiterführenden Schule mögliche Kommunikationen zwischen Systemenv orgestellt, wobei in der Nomenklatur der Systemtheorie potenzielle Kommunikationsschwierigkeiten fokussiert werden. Die dadurch gewonnenen Erkenntnisse berücksichtigend wird das Modell in einem nächsten Schritt mittels der systemtheoretischen Überlegungen zu diesem Übergang weiterentwickelt. Nach einer kritischen Diskussion der gewonnen Ergebnisse werden abschließend die Limitationen sowie praktische Implikationen dieser Arbeit aufgezeigt

Elastic-plastic-creep analysis of thermal ratchetting in straight pipe and comparisons with test results

From winter meeting of American Society of Mechanical Engineers; Detroit, Michigan, USA (11 Nov 1973). An experimental and analytical study of ratchetting in a simple structural component is described. A straight pipe from a wellcharacterized heat of Type 304 stainless steel was subjected to a series of thermal downshocks followed by sustained periods of high-temperature operation under internal pressure. The test was performed in a special sodium test facility built for the purpose. The inelastic analysis predictions were obtained using a one-dimensional finite-element procedure, and they were based on interim constitutive equations that have been recommended for use in design analyses of liquid-metal fast-breeder reactor components. The agreement between the measured and predicted ratchetting behavior is good. (8 references) (auth