Tratamento do problema de contato-impacto entre corpos flexíveis em grandes deformações pelo método dos elementos finitos

O tratamento do problema de contato entre corpos flexíveis foi implementado no módulo METAFOR4, que permite o tratamento de problemas de conformacáo mecanica. O presente algoritmo emprega o método da penalidade para o cálculo de forcas de contato. Os elementos de contato sáo percorridos duas vezes em cada passo de tempo para que seja assegurada a deteccáo de todas as formas de interpenetracao. O algoritmo apresentou-se extremamente robusto. Um exemplo de impacto entre um tubo e uma placa é mostrado.The treatment of the contact problem between flexible bodies has been implemented in the METAFOR modulus4, which allows the treatment of metal forming problems. The described algorithm uses the penalty method for the calculation of the contact forces. The contact elements are checked twice at each time step to assure the detection of al1 forms of penetration. The algorithm demonstrated to be extremely robust. An example of impact between a tube and a plate is given.Peer Reviewe

Tratamento do problema de contato-impacto entre corpos flexíveis em grandes deformações pelo método dos elementos finitos

O tratamento do problema de contato entre corpos flexíveis foi implementado no módulo METAFOR4, que permite o tratamento de problemas de conformacáo mecanica. O presente algoritmo emprega o método da penalidade para o cálculo de forcas de contato. Os elementos de contato sáo percorridos duas vezes em cada passo de tempo para que seja assegurada a deteccáo de todas as formas de interpenetracao. O algoritmo apresentou-se extremamente robusto. Um exemplo de impacto entre um tubo e uma placa é mostrado.The treatment of the contact problem between flexible bodies has been implemented in the METAFOR modulus4, which allows the treatment of metal forming problems. The described algorithm uses the penalty method for the calculation of the contact forces. The contact elements are checked twice at each time step to assure the detection of al1 forms of penetration. The algorithm demonstrated to be extremely robust. An example of impact between a tube and a plate is given.Peer Reviewe

Intraguild aggressiveness between an alien and a native predatory mite

The predatory mite Amblydromalus limonicus, non-native in Europe, can be used legally in several European countries as greenhouse biocontrol agent against thrips species, although this species is also able to feed on whiteflies and gall mites. The first record of the unintended occurrence of A. limonicus in apple orchards in Europe comes from Catalonia (Spain), where A. limonicus is well established in the native predatory mite community since 2011. The dominant species in this community is Amblyseius andersoni, which has a similar life-style as A. limonicus (large, aggressive predator with broad diet range) making intraguild (IG) interactions between the two predators likely. Thus, we tested the IG aggressiveness of native and alien female predators, when provided with IG prey (larvae). Alien females of A. limonicus proved to be highly aggressive IG predators against native larvae of A. andersoni, which were attacked earlier and more frequently than alien larvae by the native predator. Nearly all attacks by the alien predator resulted in the death of native IG prey, whereas about 10% of the alien intraguild prey escaped the attacks of the native predator. Additionally, native IG prey is smaller than alien prey, which should facilitate the overwhelming by the alien predator. We argue that the strong aggressive intraguild behavior of A. limonicus is contributing to its establishment success in the native predatory mite community.info:eu-repo/semantics/acceptedVersio

Denitrification-derived nitric oxide modulates biofilm formation in Azospirillum brasilense

Azospirillum brasilense is a rhizobacterium that provides beneficial effects on plants when they colonize roots. The formation of complex bacterial communities known as biofilms begins with the interaction of planktonic cells with surfaces in response to appropriate signals. Nitric oxide (NO) is a signaling molecule implicated in numerous processes in bacteria, including biofilm formation or dispersion, depending on genera and lifestyle. Azospirillum brasilense Sp245 produces NO by denitrification having a role in root growth promotion. We analyzed the role of endogenously produced NO on biofilm formation in A. brasilense Sp245 and in a periplasmic nitrate reductase mutant (napA::Tn5; Faj164) affected in NO production. Cells were statically grown in media with nitrate or ammonium as nitrogen sources and examined for biofilm formation using crystal violet and by confocal laser microscopy. Both strains formed bio- films, but the mutant produced less than half compared with the wild type in nitrate medium showing impaired nitrite production in this condition. NO measurements in biofilm confirmed lower values in the mutant strain. The addition of a NO donor showed that NO influences biofilm formation in a dose-dependent manner and reverses the mutant phenotype, indicating that Nap positively regulates the formation of biofilm in A. brasilense Sp245.Fil: Arruebarrena Di Palma, Andrés. Universidad Nacional de Mar del Plata; Argentina. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Buenos Aires Sur. Estación Experimental Agropecuaria Balcarce; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Pereyra, Cintia Mariana. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Buenos Aires Sur. Estación Experimental Agropecuaria Balcarce; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Mar del Plata; ArgentinaFil: Moreno Ramírez, Lizbeth. Benemérita Universidad Autónoma de Puebla; MéxicoFil: Xiqui Vazquez, Maria L.. Benemérita Universidad Autónoma de Puebla; MéxicoFil: Baca, Beatriz E.. Benemérita Universidad Autónoma de Puebla; MéxicoFil: Pereyra, María Alejandra. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Buenos Aires Sur. Estación Experimental Agropecuaria Balcarce; Argentina. Universidad Nacional de Mar del Plata; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Lamattina, Lamattina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Biológicas. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Biológicas; ArgentinaFil: Creus, Cecilia Mónica. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Buenos Aires Sur. Estación Experimental Agropecuaria Balcarce; Argentina. Universidad Nacional de Mar del Plata; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

La ingesta de una fuente vegetal de ácido α-linolénico (Salvia hispanica L.) mejora alteraciones renales inducidas por una dieta rica en sacarosa

El síndrome metabólico (SM) humano actualmente alcanza proporciones epidémicas en todo el mundo. Por lo tanto, resulta esencial identificar estrategias nutricionales efectivas a fin prevenir/atenuar la progresión de las patologías asociadas. Numerosa evidencia ha demostrado que los ácidos grasos poliinsaturados n-3 (EPA, DHA y ALA) impactan positivamente sobre varias de las anomalías presentes en el SM (dislipidemia, sensibilidad insulínica, adiposidad visceral, entre otras). Sin embargo, es escaso el conocimiento de sus efectos sobre el daño renal asociado al SM.Fil: Creus, Agustina . Universidad Nacional del LitoralFil: D`Alessandro, María E.. Universidad Nacional del Litora

Study of nuclear recoils in liquid argon with monoenergetic neutrons

For the development of liquid argon dark matter detectors we assembled a setup in the laboratory to scatter neutrons on a small liquid argon target. The neutrons are produced mono-energetically (E_kin=2.45 MeV) by nuclear fusion in a deuterium plasma and are collimated onto a 3" liquid argon cell operating in single-phase mode (zero electric field). Organic liquid scintillators are used to tag scattered neutrons and to provide a time-of-flight measurement. The setup is designed to study light pulse shapes and scintillation yields from nuclear and electronic recoils as well as from {\alpha}-particles at working points relevant to dark matter searches. Liquid argon offers the possibility to scrutinise scintillation yields in noble liquids with respect to the populations of the two fundamental excimer states. Here we present experimental methods and first results from recent data towards such studies.Comment: 9 pages, 8 figures, proceedings of TAUP 2011, to be published in Journal of Physics: Conference Series (JCPS

Microscopic spheroidal particles obtained by laser cutting

In this work we study the characteristics of the particles ejected from the cutting zone of a SAE 1010 steel while using a CO2 gaseous laser with the purpose of determining the feasibility to use this technique in the production of microscopic particles for nuclear applications [2] as well as for other scientific and technological uses [1].Instituto de Física La Plat

In vitro PGPR properties and osmotic tolerance of different Azospirillum native strains and their effects on growth of maize under drought stress

Osmotic variations in the soil can affect bacterial growth diminishing the number ofinoculated bacteria. In a scenario of water deficit having tolerant bacteria would bebeneficial to achieve a better response of the plant to stress. Thus, selection of moreresistant bacteria could be useful to design new inoculants to be used in arid zones. In thissense, a group of Azospirillum isolates deposited in INTA collection was characterized inorder to select strains tolerant to osmotic stress. The results obtained demonstrated that Az19 strain has similar in vitro PGPR characteristics to Az39, the most used strain inArgentina for inoculants industries, with the advantage of a better tolerance to osmotic andsalt stress. Inoculation of maize plants with this strain resulted in a better response againstwater deficit compared to Az39 strain, encouraging us to further study the behavior of thisstrain in greenhouse and field trials in view of developing new inoculants suitable for areaswith water deficit.Fil: García, Julia E.. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigación en Ciencias Veterinarias y Agronomicas. Instituto de Microbiología y Zoología Agrícola; ArgentinaFil: Maroniche, Guillermo Andrés. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Buenos Aires Sur. Estación Experimental Agropecuaria Balcarce; ArgentinaFil: Creus, Cecilia Mónica. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Buenos Aires Sur. Estación Experimental Agropecuaria Balcarce; ArgentinaFil: Suarez Rodriguez, Ramón. Universidad Autónoma del Estado de Morelos; MéxicoFil: Ramirez Trujillo, José Augusto. Universidad Autónoma del Estado de Morelos; MéxicoFil: Groppa, María Daniela. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Reconstrucción paleoclimática y paleoambiental de la Península Ibérica durante el Cuaternario, aplicación de modelos geoprospectivos para la evaluación de escenarios futuros

Esta comunicación trata de resumir el trabajo realizado por el ITGE, BRGM, CCMA, IPE, ETSIMM y ENRESA en el proyecto titulado "Paleoclimatological Revision of Climate Evolution and Environment in Western Mediterranean Region. Evaluation of future evolution scenarios in the Iberian Peninsula", en el marco del Programa de la Comisión de las Comunidades Europeas sobre Gestión y Almacenamiento de Residuos Radioactivos (contrato CEC FI2WCT91- 0075)

Dynamics of surface alloying promoted by cadmium underpotential deposition-anodic stripping cycles on irregular silver electrodeposits

The underpotential deposition of Cd from dilute aqueous 5 × 10−3 M CdSO4 + 0.5 M Na2SO4 + 0.01 M H2SO4 on Ag electrodeposits grown on polyfaceted Pt single-crystal microspheres was studied using potentiodynamic and potentiostatic techniques, transmission electron diffraction, scanning tunneling microscopy and X-ray photoelectron spectroscopy. Ag electrodeposits were grown in 5 × 10−3 M Ag2SO4 + 0.5 M Na2SO4 + 0.01 M H2SO4 at cathodic overpotentials ηc of −0.06 V and −0.58 V to form a columnar and dendritic Ag surface respectively. Surface rearrangement processes involving the formation of Cd + Ag alloys were studied by stripping voltammetry after the potential was held for a certain time at different preset values covering the potential range in which the degree of surface coverage by Cd atoms was less than or close to unity (θc⩽ 1) on both Ag surfaces. Surface diffusion and penetration of Cd atoms into bulk Ag for θc⩽ 1 are discussed. A place-exchange mechanism is advanced to account for the kinetics of Cd + Ag alloy formation.Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicada