Controlled interactions between silanol groups at the surface of sepiolite and an acrylate matrix: Consequences on the thermal and mechanical properties

Elastomer filled with fibrous clay (sepiolite) was manufactured using a hydrophilic elastomer matrix, poly 2-hydroxyethylacrylate (PHEA). The surface silanol groups located onto the channel sides of the sepiolite were functionalized with both octyltrimethoxysilane (OTMS) and 3-methacryloxypropyltrimethoxysilane (MPTMS), which form covalent bonds with the mineral surface and modify their properties. After the grafting of OTMS, PHEA is in contact with a non-polar chain, which prevents matrix–filler interactions. After the grafting of MPTMS, covalent bonds are formed between the acrylate groups of PHEA and MPTMS, which increase the matrix–filler interactions. After functionalization, there is no change in the structural and zeolitic water of the sepiolite which conserves its hydrophilic character. So, an equivalent distribution of the pristine and modified sepiolite is detected in the elastomeric matrices on transmission electron microscopy views of ultramicrotome cuts. The elastomeric macroscopic behavior is therefore related to the PHEA–sepiolite interactions. We show that the stronger the host–matrix interactions, the more important is the reinforcement effect. A direct relation between the interaction strength and the improvement of the mechanical properties was established. The control of the nature, quantity, and localization of the molecules grafted on the sepiolite surface allows us to manage the mechanical properties.     

Transparent conducting films from NbSe3 nanowires

We have developed methods to disperse and partially size separate NbSe(3) nanowires in aqueous surfactant solutions. These dispersions can easily be formed into thin films. Optical and electrical studies show these films to display sheet resistances and transmittances ranging from (460 Ω/□, 22%) to (12 kΩ/□, 79%) depending on thickness. For thicker films, we measured the transparent conducting figure of merit to be σ(DC, B)/σ(Op) = 0.32, similar to graphene networks. Thickness measurements gave individual values of σ(Op) = 17,800 S m(-1) and σ(DC, B) = 5700 S m(-1). Films thinner than ～ 70 nm displayed reduced DC conductivity due to percolative effects.     

Direct Social Contacts Override Auditory Information in the Song-Learning Process in Starlings (Sturnus vulgaris).

Social influence on song acquisition was studied in 3 groups of young European starlings raised under different social conditions but with the same auditory experience of adult song. Attentional focusing on preferred partners appears the most likely explanation for differences found in song acquisition in relation to experience, sex, and song categories. Thus, pair-isolated birds learned from each other and not from broadcast live songs, females did not learn from the adult male tutors, and sharing occurred more between socially associated peers. On the contrary, single-isolated birds clearly copied the adult songs that may have been the only source of attention stimulation. Therefore, social preference appears as both a motor for song learning and a potential obstacle for acquisition from nonpreferred partners, including adults. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Motivations to identify with social groups: A look at their positive and negative consequences.

Social identity is considered a key social psychological variable to understanding intergroup behaviors. Given that social identity has been associated with both positive (e.g., well-being, helping behaviors) and negative consequences (e.g., ingroup bias, nationalism), it remains to be explained which dimensions of social identification yield these divergent consequences. To this aim, these studies apply self-determination theory to understanding the reasons why group members identify with their ingroup. We hypothesized that when group members identify with their ingroup for self-determined reasons, this should predict more positive consequences. In contrast, identifying with one's ingroup for non–self-determined reasons should predict more negative consequences. Three studies tested these hypotheses among members of different social groups, namely, University of Queensland students (n = 272), residents of Québec (n = 196), and members of an online community (n = 278). Controlling for degree of identification, these hypotheses were supported when predicting the positive consequences, and mostly supported for the negative consequences. Results are interpreted in light of social identity theory and self-determination theory. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Propriétés psychométriques d'une version canadienne-fran?aise du Questionnaire des expériences dépressives.

The present study evaluates a French-Canadian version of the Depressive Experiences Questionnaire, originally developed by Blatt, D'Afflitti, et Quinlan (1976), to measure two personality dimensions predisposing to depressive affect, Dependency and Self-Criticism. Factor analysis with 762 undergraduate students showed a very high degree of conformity with the original version in terms of the number of factors, variance explained and the pattern of factor loadings for each scale. Congruence of factor scores calculated with the solutions derived from the English and French principal component analysis was very high, but somewhat lower for the Self-critical dimension for male subjects. The scales of the French-Canadian Questionnaire des Expériences Dépressives correlated with a measure of depression, and showed adequate test-retest reliability over an 8-week period. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Subthalamic nucleus stimulation affects fear and sadness recognition in Parkinson’s disease.

Bilateral subthalamic nucleus (STN) deep brain stimulation (DBS) in Parkinson’s disease (PD) can produce emotional disorders that have been linked to disturbance of the STN’s limbic territory. The aim of this study was to confirm the impairment of the recognition of facial emotions (RFE) induced by STN DBS, not only ruling out the effect of the disease’s natural progression in relation to the effect of DBS, but also assessing the influence of modifications in dopamine replacement therapy (DRT) following STN DBS. RFE was investigated in 24 PD patients who underwent STN DBS and 20 PD patients treated with apomorphine. They were assessed 3 months before and after treatment. The 2 patient groups were compared with a group of 30 healthy matched controls. The results showed that RFE for negative emotions (fear and sadness) was impaired in only the STN DBS group in the posttreatment condition and was unrelated to DRT. Results confirm the selective reduction of RFE induced by STN DBS, due neither to the disease’s natural progression nor to modifications in DRT. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Review of Microstructure–Mechanical Property Relationships in Cast and Wrought Ni-Based Superalloys with Boron,Carbon, and Zirconium Microalloying Additions

Cast and wrought Ni-based superalloys are materials of choice for harsh high-temperature environments of aircraft engines and gas turbines. Their compositional complexity requires sophisticated thermo-mechanical processing. A typical microstructure consists of a polycrystalline γ-matrix, strengthening Ni₃(Al,Ti) γ′ precipitates, carbides (MC, M₆C, and M₂₃C₆), borides (M₂B, M₃B₂, and M₅B₃), and other inclusions. Microalloying additions of B, C, and Zr commonly improve high-temperature strength and creep resistance, although excessive additions are detrimental. Grain boundary (GB) segregation may improve cohesion and displace embrittling impurities. Finely dispersed carbides and borides are desired to control grain size via GB pinning. However, excessive decoration of GBs may lead to failure during processing and in-service. Hence, a systematic review on the roles of B, C, and Zr in cast and wrought Ni-based superalloys is required. The current state of knowledge on GB segregation and precipitation is reviewed. Experimental and modeling results are compared across various processing steps. The impact of GB precipitation on mechanical properties is most well researched. Co-precipitation in proximity to GBs interacting with local microstructure evolution and mechanical properties remains less explored. Addressing these gaps in knowledge allows a more complete understanding of processing–microstructure–properties relationships in advanced cast and wrought Ni-based superalloys.     

La numération de position : où en sont les connaissances d'élèves québécois?

RÉSUMÉ

La numération a fait l'objet d'études importantes, notamment au Québec, durant les années 1980–2000. Les études ont révélé sa complexité ainsi que les difficultés que posent à la fois son enseignement et son apprentissage. La présente étude s'inscrit dans le prolongement d'une suite d'études didactiques sur ces difficultés. Plus précisément, elle investigue les connaissances d'élèves québécois de 3^e année primaire sur la numération de position et les compare à celles d'une recherche phare menée par Bednarz et Dufour-Janvier dont les résultats ont fait l'objet de plusieurs publications (1982 Bednarz, N. et Dufour-Janvier, B. (1982). The understanding of numeration in primary school. Educational Studies in Mathematics, 13, 33–57. [Google Scholar], 1984a Bednarz, N. et Dufour-Janvier, B. (1984a). La numération: les difficultés suscitées par son apprentissage ; une stratégie didactique cherchant à favoriser une meilleure compréhension. Grand N, 33, 5–31. [Google Scholar], 1984b Bednarz, N. et Dufour-Janvier, B. (1984b). La numération: une stratégie didactique cherchant à favoriser une meilleure compréhension. Grand N, 34, 1–17. [Google Scholar], 1988 Bednarz, N. et Dufour-Janvier, B. (1988). A constructivist approach to numeration in primary school: Results of a three year intervention with the same group of children. Educational Studies in Mathematics, 19, 299–331. [Google Scholar]). Les résultats de notre étude montrent que si 30 ans ont passé depuis la recherche de Bednarz et Dufour-Janvier, peu de changements sont observés dans les conduites mathématiques des élèves en numération. Quelques hypothèses, relatives à la fois aux contraintes d'enseignement et aux difficultés spécifiques d'appropriation de la numération sont, au terme de l'article, formulées pour expliquer ces résultats.     

A Multi-formalism Approach for the Validation of UML Models

Our approach is based on UML models. They are edited with the rational Rose^™ tool [Rat96] and complemented with annotations that state several constraints. The class diagram is the starting point of a translation process that produces formal specifications in Z [Spi92] and Lustre [CHP87]. The RoZ tool is used to translate the class diagram into Z automatically. The Z and Lustre specifications are used to validate the UML models by means of a prover and a testing environment. Received February 2000 / Accepted in revised form December 2000     

A program for individual and population optimal design for univariate and multivariate response pharmacokinetic-pharmacodynamic models

The design of pharmacokinetic and pharmacodynamic experiments concerns a number of issues, among which are the number of observations and the times when they are taken. Often a model is used to describe these data and the pharmacokinetic-pharmacodynamic behavior of a drug. Knowledge of the data analysis model at the design stage is beneficial for collecting patient data for parameter estimation. A number of criteria for model-oriented experiments, which maximize the information content of the data, are available. In this paper we present a program, Popdes, to investigate the D-optimal design of individual and population multivariate response models, such as pharmacokinetic-pharmacodynamic, physiologically based pharmacokinetic, and parent drug and metabolites models. A pre-clinical and clinical pharmacokinetic-pharmacodynamic model describing the concentration-time profile and effect of an oncology compound in development is used for illustration.