Texture Evolution of AZ31 Magnesium Alloy Sheet at High Strain Rates

In the current contribution the mechanical behaviour at high strain rates of AZ31 magnesium alloy sheet is studied. Uniaxial deformation properties were studied by means of tensile split Hopkinson pressure bar (SHPB) at different temperatures. The influence of the strain rate and temperature on the deformation mechanisms was investigated by means of electron backscatter diffraction (EBSD) and neutron diffraction. It is shown that twinning plays an important role on high strain rate deformation of this alloy, even at elevated temperatures. Significant evidence of prismatic slip as a deformation mechanism is observed, also at warm temperatures, leading to the alignment of directions with the tensile axis and to a spread of the intensities of the basal pole figure towards the in-plane direction perpendicular to the tensile axis. The rate of decrease of the CRSS of non-basal systems is observed to be slower than at quasi-static rates. Secondary twinning and pyramidal slip were also outlined for some conditions. At warm temperatures, in contrast to quasi-static range, a generalized dynamic recrystallization is not observed. Moreover, the activation of rotational recrystallization mechanisms is reporte

Twinning and grain subdivision during dynamic deformation of a Mg AZ31 sheet alloy at room temperature

The microstructural evolution of an AZ31 rolled sheet during dynamic deformation at strain rates of ∼103 s−1 has been investigated by electron backscatter diffraction, X-ray and neutron diffraction. The influence of orientation on the predominant deformation mechanisms and on the recovery processes taking place during deformation has been systematically examined. The results have been compared with those corresponding to the same alloy tested quasi-statically under equivalent conditions. It has been found that strain rate enhances the activation of extension twinning dramatically, while contraction and secondary twinning are not significantly influenced. The polarity of extension twinning is even reversed in some grains under selected testing conditions. Significant grain subdivision by the formation of geometrically necessary boundaries (GNBs) takes place during both quasi-static and dynamic deformation of this AZ31 alloy. It is remarkable that GNBs of high misorientations form even at the highest strain rates. The phenomenon of recovery has been found to be orientation dependen

Identification of structural motifs as tunneling two-level systems in amorphous alumina at low temperatures

One of the most accepted models that describe the anomalous thermal behavior of amorphous materials at temperatures below 1 K relies on the quantum mechanical tunneling of atoms between two nearly equivalent potential energy wells forming a two-level system (TLS). Indirect evidence for TLSs is widely available. However, the atomistic structure of these TLSs remains an unsolved topic in the physics of amorphous materials. Here, using classical molecular dynamics, we found several hitherto unknown bistable structural motifs that may be key to understanding the anomalous thermal properties of amorphous alumina at low temperatures. We show through free energy profiles that the complex potential energy surface can be reduced to canonical TLSs. The tunnel splitting predicted from instanton theory, the number density, dipole moment, and coupling to external strain of the discovered motifs are consistent with experiments.We acknowledge financial support from the Marie Curie International Incoming Fellowship (Grant Agreement PIIF-GA-2012-326435 RespSpatDisp) and the European Research Council Advanced Grant DYNamo (ERC-2010-AdG-267374), both within the 7th European Community Framework Programme. We also thank “ayuda para la Especializacion de Personal Investigador del Vicerrectorado de Investigacion UPV/EHU-2013”, Grupos Consolidados UPV/EHU del Gobierno Vasco (IT-578-13), and the Ikerbasque Foundation. This research was supported, in part, by a grant of computer time from the CUNY HPC under NSF Grants CNS-0855217, CNS-0958379, and ACI-1126113.Peer Reviewe

Identificación de regiones genómicas de almendro en progenies de híbridos interespecíficos (abstract)

La mejora genética de portainjertos tiene por objetivo obtener diferentes híbridos interespecíficos y combinar la tolerancia a estreses abióticos. Distintos cruzamientos entre almendro, melocotonero y ciruelo se están estudiado para su adaptación a un amplio rango de condiciones edafoclimáticas. En este estudio analizamos 49 individuos de cuatro progenies de híbridos interespccíficos de tres especies y sus parentales (dos ciruelos mirobolanes: 'P.2175' y 'P.2980'; los híbridos almendro x melocotonero 'Garnem' y 'Felinem'; el almendro 'Garfi'; y el melocotonero 'Nemared'). Se analizaron 48 SSRs polimórficos en los parentales a lo largo de los 8 grupos de ligamiento a partir de varios mapas de referencia de Prunus. El dendrograma UPGMA generado con la variabilidad genética observada, clasificó los genotipos en 5 grupos, permitiéndonos diferenciar en nuestras progenies las regiones genómicas del almendro entre las regiones del melocotonero y el ciruelo. En estas regiones se va a llevar a cabo el estudio de distintos genes implicados en la tolerancia a la sequía, puesto que el almendro es más tolerante que las otras dos especies, melocotonero y cirueloPublishe

Identification of almond genomic regions in four 3-way interspecific hybrid progenies (abstract)

Publishe

Situacions d'aula. Materials docents d'ús interdisciplinari

Presentem material de treball per a la formació del professorat d’Educació Infantil i Primària. Les situacions que presentem són les següents: I) «Hi ha boira al Grau de Castelló». L’Escriptura d’una notícia. ceip «La Marina». En aquesta situació, un grup de xiquets i xiquetes d’Educació Infantil, de 5 anys, amb la seua mestra, escriuen de manera col•lectiva una notícia (Durada de la tasca: 28 min.). II) «Pasamos lista». ceip «Lluís Vives». En aquesta situació, un grup de xiquets i xiquetes de 4 anys, junt amb la seua mestra, passen llista al començament de la classe per comprovar que els xiquets han anat a l’escola aquell dia (Durada de la tasca: 5 min. 30 s.) III) «El Caballo». Reelaboració del coneixement a partir d’un projecte de treball globalitzat. ceip «Lluís Vives». En aquesta situació, un grup de xiquets i xiquetes de 4 anys i la seua mestra tracten de recordar les activitats realitzades al llarg d’un projecte de treball globalitzat sobre «El Caballo» amb la finalitat de donar-les a conèixer als seus companys d’altres cursos i a altres persones. (Durada de la tasca: 27 min.) En cada situació mostrem la interacció oral i les activitats realitzades per la mestra i els xiquets, per a portar a terme la tasca que s’han proposat. La llengua utilitzada en les interaccions en l’aula (castellà o valencià) s’ha mantingut en la transcripció. Les transcripcions, obtingudes a partir de l’enregistrament en vídeo, divideixen el temps en episodis i seqüències. Cada episodi està constituït per un segment de transcripció que reflecteix una activitat central dins de la tasca, en relació amb el contingut d’ensenyament (per exemple, planificar o escriure una part del text, corregir el text escrit en la pissarra, passar llista, elegir el tema d’un projecte, etc.). Les seqüències representen unitats d’acció i/o temàtiques dins de l’episodi, i es troben aïllades en funció de la seua finalitat, per facilitar-ne la comprensió i l’anàlisi.We present working material for teacher training and Primary Education. The situations presented are: I) "There is fog in Grau de Castelló." Writing a story. CEIP "La Marina". In this situation, a group of boys and girls infant, 5 years old, with his teacher, so write a new collective bargaining • (task duration: 28 min.). II) "Pasamos list." ceip "Luis Vives". In this situation, a group of boys and girls 4 years, along with their teacher, go shopping at the beginning of the class to ensure that the children have gone to school that day (the task duration: 5 min. 30 s.). III) "El Caballo". Reworking of knowledge from a global project work. ceip "Luis Vives". In this situation, a group of boys and girls 4 years and their teacher trying to remember the activities carried out during a global project work on "El Caballo" to give them to know their fellow other courses and others. (Task duration: 27 min.) In each situation shows oral interaction and activities carried out by the teacher and the children, to carry out the tasks that have been proposed. The language used in the interactions in the classroom (Spanish or English) has been in the transcript. Transcripts obtained from recording video, divided into episodes and time sequences. Each episode consists of a segment of a transcript that reflects activity within the central task, in relation to the content of education (eg, plan and write some text, edit the text written on the blackboard, roll, choosing the theme of a project, etc.). The units represent sequences of action and / or themes in the episode, and are isolated based on their purpose, to facilitate understanding and analysis

Bacteriophages as fecal pollution indicators

Bacteriophages are promising tools for the detection of fecal pollution in different environments, and particularly for viral pathogen risk assessment. Having similar morphological and biological characteristics, bacteriophages mimic the fate and transport of enteric viruses. Enteric bacteriophages, especially phages infecting Escherichia coli (coliphages), have been proposed as alternatives or complements to fecal indicator bacteria. Here, we provide a general overview of the potential use of enteric bacteriophages as fecal and viral indicators in different environments, as well as the available methods for their detection and enumeration, and the regulations for their application

Local adsorption structure and bonding of porphine on Cu(111) before and after self-metalation

We have experimentally determined the lateral registry and geometric structure of free-base porphine (2H-P) and copper-metalated porphine (Cu-P) adsorbed on Cu(111), by means of energy-scanned photoelectron diffraction (PhD), and compared the experimental results to density functional theory (DFT) calculations that included van der Waals corrections within the Tkatchenko-Scheffler approach. Both 2H-P and Cu-P adsorb with their center above a surface bridge site. Consistency is obtained between the experimental and DFT-predicted structural models, with a characteristic change in the corrugation of the four N atoms of the molecule's macrocycle following metalation. Interestingly, comparison with previously published data for cobalt porphine adsorbed on the same surface evidences a distinct increase in the average height of the N atoms above the surface through the series 2H-P, Cu-P, cobalt porphine. Such an increase strikingly anti-correlates the DFT-predicted adsorption strength, with 2H-P having the smallest adsorption height despite the weakest calculated adsorption energy. In addition, our findings suggest that for these macrocyclic compounds, substrate-to-molecule charge transfer and adsorption strength may not be univocally correlated