Dynamics of elastocapillary rise

We present the results of a combined experimental and theoretical investigation of the surface-tension-driven coalescence of flexible structures. Specifically, we consider the dynamics of the rise of a wetting liquid between flexible sheets that are clamped at their upper ends. As the elasticity of the sheets is progressively increased, we observe a systematic deviation from the classical diffusive-like behaviour: the time to reach equilibrium increases dramatically and the departure from classical rise occurs sooner, trends that we elucidate via scaling analyses. Three distinct temporal regimes are identified and subsequently explored by developing a theoretical model based on lubrication theory and the linear theory of plates. The resulting free-boundary problem is solved numerically and good agreement is obtained with experiments

The hydrogen isotopic composition of fossil micrometeorites: Implications for the origin of water on Earth.

Accepted versio

Nuclear break-up of 11Be

The break-up of 11Be was studied at 41AMeV using a secondary beam of 11Be from the GANIL facility on a 48Ti target by measuring correlations between the 10Be core, the emitted neutrons and gamma rays. The nuclear break-up leading to the emission of a neutron at large angle in the laboratory frame is identified with the towing mode through its characteristic n-fragment correlation. The experimental spectra are compared with a model where the time dependent Schrodinger equation (TDSE) is solved for the neutron initially in the 11 Be. A good agreement is found between experiment and theory for the shapes of neutron experimental energies and angular distributions. The spectroscopic factor of the 2s orbital is tentatively extracted to be 0.46+-0.15. The neutron emission from the 1p and 1d orbitals is also studied

Mechanical tuning of the evaporation rate of liquid on crossed fibers

We investigate experimentally the drying of a small volume of perfectly wetting liquid on two crossed fibers. We characterize the drying dynamics for the three liquid morphologies that are encountered in this geometry: drop, column and a mixed morphology, in which a drop and a column coexist. For each morphology, we rationalize our findings with theoretical models that capture the drying kinetics. We find that the evaporation rate depends significantly on the liquid morphology and that the drying of liquid column is faster than the evaporation of the drop and the mixed morphology for a given liquid volume. Finally, we illustrate that shearing a network of fibers reduces the angle between them, changes the morphology towards the column state, and so enhances the drying rate of a volatile liquid deposited on it

Phytochemical and crystallographic studies of Azara dentata extracts and its cytotoxic effects on human breast cancer cell, MCF-7

Azara dentata Ruiz & Pav. also called “Corcolen” is an endemic shrub of Chile. The honey produced in areas with abundance of Azara dentata is highly appreciate by its polyphenols. In the present work, we isolated and identified for the first time the phytochemical components of Azara dentata and its cytotoxic effects were analyzed on cancer cells together with its antimicrobial activity. The results showed that palmitic acid methyl ester, linolenic acid methyl ester, α-tocopherol and β-sitosterol are the main non-polar constituents of the plant, while the compounds AD-3 (3-phenylisocoumarin, 0.0001% yield) and AD-4 (methyl 2-phenacyl-benzoate, 0.00039% yield) were isolated by column chromatography with n-hexane/EtOAc (3:2 v/v) and their structures were determined using NMR analysis. In addition, the structure of AD-4 was complemented by a single crystal x-ray structural determination. Azara dentata showed moderate antibacterial activity against S. aureus and S. epidermidis with a MIC of 5.0 and 10 mg/mL respectively. The cytotoxic activity of Azara dentata against MCF-7 cancer cells showed an IC50 of 15.63 µg/mL, this is a promissory value for the deeper study of its metabolites in cancer models.Fil: Paz, Cristian. Universidad de La Frontera; ChileFil: González Chavarría, Iván. Universidad de Concepción; ChileFil: Freire Espeleta, Eleonora. Comisión Nacional de Energía Atómica. Gerencia del Área de Investigaciones y Aplicaciones no Nucleares. Gerencia de Física (Centro Atómico Constituyentes); Argentina. Universidad Nacional de San Martín. Escuela de Ciencia y Tecnología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Ortiz, Leandro. Universidad Austral de Chile; ChileFil: Karpiński, Tomasz M.. Poznan University Of Medical Sciences; PoloniaFil: Duprat, Felix. Universidad de Concepción; ChileFil: Baggio, Ricardo Fortunato. Comisión Nacional de Energía Atómica. Gerencia del Área de Investigaciones y Aplicaciones no Nucleares. Gerencia de Física (Centro Atómico Constituyentes); Argentin

Mechanism for the Singlet to Triplet Superconductivity Crossover in Quasi-One-Dimensional Organic Conductors

Superconductivity of quasi-one-dimensional organic conductors with a quarter-filled band is investigated using the two-loop renormalization group approach to the extended Hubbard model for which both the single electron hopping t_{\perp} and the repulsive interaction V_{\perp} perpendicular to the chains are included. For a four-patches Fermi surface with deviations to perfect nesting, we calculate the response functions for the dominant fluctuations and possible superconducting states. By increasing V_{\perp}, it is shown that a d-wave (singlet) to f-wave (triplet) superconducting state crossover occurs, and is followed by a vanishing spin gap. Furthermore, we study the influence of a magnetic field through the Zeeman coupling, from which a triplet superconducting state is found to emerge.Comment: 11 pages, 15 figures, published versio

The Supernova Triggered Formation and Enrichment of Our Solar System

We investigate the enrichment of the pre-solar cloud core with short lived radionuclides (SLRs), especially 26Al. The homogeneity and the surprisingly small spread in the ratio 26Al/27Al observed in the overwhelming majority of calcium-aluminium-rich inclusions (CAIs) in a vast variety of primitive chondritic meteorites places strong constraints on the formation of the the solar system. Freshly synthesized radioactive 26Al has to be included and well mixed within 20kyr. After discussing various scenarios including X-winds, AGB stars and Wolf-Rayet stars, we come to the conclusion that triggering the collapse of a cold cloud core by a nearby supernova is the most promising scenario. We then narrow down the vast parameter space by considering the pre-explosion survivability of such a clump as well as the cross-section necessary for sufficient enrichment. We employ numerical simulations to address the mixing of the radioactively enriched SN gas with the pre-existing gas and the forced collapse within 20kyr. We show that a cold clump of 10Msun at a distance of 5pc can be sufficiently enriched in 26Al and triggered into collapse fast enough - within 18kyr after encountering the supernova shock - for a range of different metallicities and progenitor masses, even if the enriched material is assumed to be distributed homogeneously in the entire supernova bubble. In summary, we envision an environment for the birth place of the Solar System 4.567Gyr ago similar to the situation of the pillars in M16 nowadays, where molecular cloud cores adjacent to an HII region will be hit by a supernova explosion in the future. We show that the triggered collapse and formation of the Solar System as well as the required enrichment with radioactive 26Al are possible in this scenario.Comment: 12 pages, 8 figures, accepted for publication in ApJ. Resolution of most figures degraded to fit within arXiv size limits. A full resolution version is available at http://www.usm.uni-muenchen.de/~gritschm/Gritschneder_2011_sun.pd