89 research outputs found
Life history of Capnia bifrons (Newman, 1838) (Plecoptera, Capniidae) in a small Apennine creek (NW Italy)
Life history of Capnia bifrons (Newman, 1838) (Plecoptera, Capniidae) in a small Apennine creek (NW Italy)
Living apart together: on the biology of two sympatric Leuctra species (Plecoptera, Leuctridae) in an Apenninic stream, Italy
Water insertion and combined interstitial-vacancy oxygen conduction in the layered perovskites La1.2Sr0.8−xBaxInO4+δ
Layered perovskites of K2NiF4-type consist of single octahedral sheets alternating with NaCl-type layers, containing a substantial interstitial space. Based on the parent LaSrInO4+δ oxide, the series of title compounds have been prepared and investigated as possible solid electrolytes for solid-oxide fuel cells (SOFC). A charge misbalance is created by departure from the La/Sr = 1 : 1 ratio, favoring the insertion of extra oxygen atoms. The oxygen diffusion is further favored by introducing large Ba2+ ions, expanding the unit-cell size. Surprisingly, the presence of basic Ba ions drives the spontaneous insertion of water molecules in the interstitial space, as unveiled by a neutron powder diffraction (NPD) study at RT. Moreover, H2O molecules are split within the structure with protons bonded to the axial oxygens of the InO6 octahedra, and with OH units occupying the interstitial space. Electrical Conductivity measurements were made. The dc conductivity was measured under different oxygen partial pressures for both Ba-doped compounds at 600 °C and 800 °C showing mixed ionic and p-type electronic behavior at different oxygen partial pressures but with conductivities of the order of ≈10−4 (S cm−1), far below the conductivities values of the oxide electrodes used in SOFCs. To analyze the nature of the majority charge carrier, ac impedance spectroscopy (IS) was applied. In the temperature range 500-900 °C, La1.2Sr0.6Ba0.2InO4+δ oxide exhibits a conductivity improvement with respect to La1.2Sr0.8InO4+δ. Temperature-dependent NPD data show at 600 °C and 800 °C the presence of oxygen vacancies at the axial octahedral positions as well as interstitial oxygen, favoring a mixed conduction mechanism for oxide ions, which may account for the enhancement of the transport properties. The present result endorses the validity of this design procedure and supports K2NiF4-related compounds as promising candidates for solid-oxide electrolytes.Fil: Troncoso, L.. Universidad Austral de Chile; ChileFil: Arce, Mauricio Damián. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Unidad Ejecutora Instituto de Nanociencia y Nanotecnología. Unidad Ejecutora Instituto de Nanociencia y Nanotecnología - Nodo Bariloche | Comisión Nacional de Energía Atómica. Unidad Ejecutora Instituto de Nanociencia y Nanotecnología. Unidad Ejecutora Instituto de Nanociencia y Nanotecnología - Nodo Bariloche; ArgentinaFil: Fernández Díaz, M. T.. Institut Laue Langevin; FranciaFil: Mogni, Liliana Verónica. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Unidad Ejecutora Instituto de Nanociencia y Nanotecnología. Unidad Ejecutora Instituto de Nanociencia y Nanotecnología - Nodo Bariloche | Comisión Nacional de Energía Atómica. Unidad Ejecutora Instituto de Nanociencia y Nanotecnología. Unidad Ejecutora Instituto de Nanociencia y Nanotecnología - Nodo Bariloche; ArgentinaFil: Alonso, J. A.. Instituto de Ciencia de Materiales de Madrid; Españ
Conservación comunitaria de la quínoa en el norte de Neuquén. Argentina
Tradicionalmente agricultores familiares de Neuquén (Argentina) cultivan quínoa (Chenopodium quinoa Willd.), el estudio pone en valor un material genético de quínoa en Varvarco. Se identificaron y entrevistaron a las familias guardianas de las semillas de quínoa; se realizaron observaciones del cultivo in situ y se validó la información en talleres con la comunidad. Los resultados mostraron que la quínoa forma parte del patrimonio histórico y cultural de Varvarco ya que contribuyó a la seguridad alimentaria en épocas de crisis económicas producto de distintos eventos históricos que afectaron económica y culturalmente al norte neuquino. Lleva al menos 90 años en la zona, el ciclo de cultivo es de noviembre a marzo, con características fenotípicas y de manejo similares a los materiales del Centro de Chile. El estudio mejora el conocimiento el comportamiento de la quínoa local para adaptar los calendarios, formas de manejo del cultivo, suelo y sanidad en otros agroecosistemas.This study aimed to highlight the local variety of Quinoa from Varvarco. The research took into account the guardian families of quinoa seeds. The team identifi ed and interviewed family farmers; the crop was observed in situ and the information was validated in workshops with the Varvarco community. The results showed that this quinoa is part of Varvarco’s historical and cultural herita-ge, it contributed to food security in times of economic crisis because of different historical events that affect the economy and culture of the north of Neuquén. This quinoa has been in this area for at least 90 years. The cultivation cycle is from November to March, its phenotypic characteristics and management are similar to Central Chile varieties. The study improves the knowledge of qui-noa behavior to adapt the calendars, forms of crop management, soil and plant protection in other agroecosystems.IPAF Región PatagónicaFil: Barrionuevo, Myrian Elisabeth. Instituto Nacional de Tecnología Agropecuaria (INTA). Área Investigación y Desarrollo Tecnología Agricultura Familiar. Región Patagonia; ArgentinaFil: Mogni, Javier Alejandro. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Bariloche. Agencia de Extensión Rural Chos-Malal; ArgentinaFil: Vázquez, A. Provincia de Neuquén. Ministerio de Producción de Industria. Dirección Regional Norte de Producción; ArgentinaFil: Navarrete, L. Universidad Nacional del Comahue. Facultad de Ciencias Agrarias; Argentin
Simulations of the inelastic response of silicon to shock compression
Recent experiments employing nanosecond white-light X-ray diffraction have demonstrated a complex response of pure, single crystal silicon to shock compression on ultra-fast timescales. We present here details of a Lagrangian code which tracks both longitudinal and transverse strains, and successfully reproduces the experimental response by incorporating a model of the shock-induced, yet kinetically inhibited, phase transition. This model is also shown to reproduce results of classical molecular dynamics simulations of shock compressed silicon
Revisiting the Crystal Structure of BaCe0.4Zr0.4Y0.2O3-δ Proton Conducting Perovskite and Its Correlation with Transport Properties
Oxides with proton conductivity have a great potential for applications in environmental energy technology. Despite the BaCe0.4Zr0.4Y0.2O3-δ (BCZY) perovskites being well-known proton conductors, it is a challenge to determine the optimal operating temperature range where the energy applications benefit most from this unique property. The protonic transport properties strongly depend on crystal structure and local distortions in the participating cation coordination sphere, according to related temperatures and gas feed. The transport and crystallographic properties of BCZY were simultaneously studied by impedance spectroscopy (IS) and synchrotron X-ray diffraction (S-XRD). A strong correlation between conductivity and the lattice parameter, corresponding in principle to a cubic symmetry, was observed, mainly between 400 and 700 °C. The protonic conductivity range was analyzed by the H/D isotopic effect on the impedance spectra, which helped to identify protonic conduction as the governing transport mechanism below 600 °C, while the transport via oxygen vacancies dominates above this temperature. In order to assess the real crystallographic structure, the simultaneous refinement of laboratory XRD and neutron diffraction (ND) patterns was performed. According to this, BCZY changes from rhombohedral symmetry below 400 °C to cubic at 600 °C in a second-order phase transition. Complementary quasielastic neutron scattering (QENS) enables us to determine a protonic jump length of 3.1 Å, which matches the O-O distances in the octahedral oxygen coordination sphere around the cations. These results support the protonic self-diffusion through proton hopping between intraoctahedral O sites as the main transport mechanism up to 600 °C.Fil: Basbus, Juan Felipe. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Unidad Ejecutora Instituto de Nanociencia y Nanotecnología. Unidad Ejecutora Instituto de Nanociencia y Nanotecnología - Nodo Bariloche | Comisión Nacional de Energía Atómica. Unidad Ejecutora Instituto de Nanociencia y Nanotecnología. Unidad Ejecutora Instituto de Nanociencia y Nanotecnología - Nodo Bariloche; ArgentinaFil: Arce, Mauricio Damián. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Unidad Ejecutora Instituto de Nanociencia y Nanotecnología. Unidad Ejecutora Instituto de Nanociencia y Nanotecnología - Nodo Bariloche | Comisión Nacional de Energía Atómica. Unidad Ejecutora Instituto de Nanociencia y Nanotecnología. Unidad Ejecutora Instituto de Nanociencia y Nanotecnología - Nodo Bariloche; ArgentinaFil: Napolitano, Federico Ricardo. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Unidad Ejecutora Instituto de Nanociencia y Nanotecnología. Unidad Ejecutora Instituto de Nanociencia y Nanotecnología - Nodo Bariloche | Comisión Nacional de Energía Atómica. Unidad Ejecutora Instituto de Nanociencia y Nanotecnología. Unidad Ejecutora Instituto de Nanociencia y Nanotecnología - Nodo Bariloche; ArgentinaFil: Troiani, Horacio Esteban. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Unidad Ejecutora Instituto de Nanociencia y Nanotecnología. Unidad Ejecutora Instituto de Nanociencia y Nanotecnología - Nodo Bariloche | Comisión Nacional de Energía Atómica. Unidad Ejecutora Instituto de Nanociencia y Nanotecnología. Unidad Ejecutora Instituto de Nanociencia y Nanotecnología - Nodo Bariloche; ArgentinaFil: Alonso, José Antonio. Instituto de Ciencia de Materiales de Madrid; EspañaFil: Saleta, Martin Eduardo. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Unidad Ejecutora Instituto de Nanociencia y Nanotecnología. Unidad Ejecutora Instituto de Nanociencia y Nanotecnología - Nodo Bariloche | Comisión Nacional de Energía Atómica. Unidad Ejecutora Instituto de Nanociencia y Nanotecnología. Unidad Ejecutora Instituto de Nanociencia y Nanotecnología - Nodo Bariloche; Argentina. Centro Nacional de Pesquisa em Energia e Materiais; BrasilFil: González, Miguel A.. Institut Laue Langevin; FranciaFil: Cuello, Gabriel Julio. Institut Laue Langevin; FranciaFil: Fernández Díaz, María Teresa. Institut Laue Langevin; FranciaFil: Pardo Sainz, Miguel. Universidad de Zaragoza. Instituto de Ciencias de Materiales de Aragon; EspañaFil: Bonanos, Nikolaos. Technical University of Denmark; DinamarcaFil: Jimenez, Catalina Elena. Helmholtz-Zentrum; AlemaniaFil: Giebeler, Lars. No especifíca;Fil: Figueroa, Santiago J. A.. Centro Nacional de Pesquisa em Energia e Materiais; BrasilFil: Caneiro, Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Unidad Ejecutora Instituto de Nanociencia y Nanotecnología. Unidad Ejecutora Instituto de Nanociencia y Nanotecnología - Nodo Bariloche | Comisión Nacional de Energía Atómica. Unidad Ejecutora Instituto de Nanociencia y Nanotecnología. Unidad Ejecutora Instituto de Nanociencia y Nanotecnología - Nodo Bariloche; ArgentinaFil: Serquis, Adriana Cristina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Unidad Ejecutora Instituto de Nanociencia y Nanotecnología. Unidad Ejecutora Instituto de Nanociencia y Nanotecnología - Nodo Bariloche | Comisión Nacional de Energía Atómica. Unidad Ejecutora Instituto de Nanociencia y Nanotecnología. Unidad Ejecutora Instituto de Nanociencia y Nanotecnología - Nodo Bariloche; ArgentinaFil: Mogni, Liliana Verónica. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Unidad Ejecutora Instituto de Nanociencia y Nanotecnología. Unidad Ejecutora Instituto de Nanociencia y Nanotecnología - Nodo Bariloche | Comisión Nacional de Energía Atómica. Unidad Ejecutora Instituto de Nanociencia y Nanotecnología. Unidad Ejecutora Instituto de Nanociencia y Nanotecnología - Nodo Bariloche; Argentin
Multipotent mesenchymal stromal cells from amniotic fluid: solid perspectives for clinical application
Inelastic response of silicon to shock compression
The elastic and inelastic response of [001] oriented silicon to laser compression has been a topic of considerable discussion for well over a decade, yet there has been little progress in understanding the basic behaviour of this apparently simple material. We present experimental x-ray diffraction data showing complex elastic strain profiles in laser compressed samples on nanosecond timescales. We also present molecular dynamics and elasticity code modelling which suggests that a pressure induced phase transition is the cause of the previously reported 'anomalous' elastic waves. Moreover, this interpretation allows for measurement of the kinetic timescales for transition. This model is also discussed in the wider context of reported deformation of silicon to rapid compression in the literature
Case report: Gastroenterological management in a case of cardio-facio-cutaneous syndrome
Backgroundcardio-facio-cutaneous syndrome is a rare genetic disorder affecting less than 900 people in the world. It is mainly characterized by craniofacial, dermatologic and cardiac defects, but also gastroenterological symptoms may be present, ranging from feeding difficulties to gastroesophageal reflux and constipation.In this report we describe a case of this syndrome characterized by severe feeding and growth difficulties, with a particular focus on the management of gastroenterological complications.Case presentationthe patient was a caucasian male affected by Cardio-Facio-Cutaneous syndrome who presented feeding difficulties already a few hours after birth. These symptoms worsened in the following months and lead to a complete growth arrest and malnutrition. He was first treated with a nasogastric tube placement. Subsequently, a laparoscopic Nissen fundoplication and a laparoscopic Stamm gastrostomy were performed. The child was fed with nocturnal enteral nutrition and diurnal oral and enteral nutrition. Eventually the patient resumed feeding validly and regained adequate growth.Conclusionthis paper aims to bring to light a complex rare syndrome that infrequently comes to the attention of the pediatricians and whose diagnosis is not always straightforward. We also highlight the possible complications under a gastroenterologic point of view. Our contribution can be helpful to the pediatrician in the first diagnostic suspect of this syndrome. In particular, it is worth highlighting that -in an infant with Noonan-like features- symptoms like suction or swallowing problems, vomiting and feeding difficulties should orient towards the diagnosis of a Cardio-facio-cutaneous syndrome. It is also important to stress that its related gastroenterological issues may lead to severe growth failure and therefore the role of the gastroenterologist is key to manage supplemental feeding and to establish whether a nasogastric or gastrostomic tube placement is necessary
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