The Lotic Intersite Nitrogen Experiments: an example of successful ecological research collaboration

Collaboration is an essential skill for modern ecologists because it brings together diverse expertise, viewpoints, and study systems. The Lotic Intersite Nitrogen eXperiments (LINX I and II), a 17-y research endeavor involving scores of early- to late-career stream ecologists, is an example of the benefits, challenges, and approaches of successful collaborative research in ecology. The scientific success of LINX reflected tangible attributes including clear scientific goals (hypothesis-driven research), coordinated research methods, a team of cooperative scientists, excellent leadership, extensive communication, and a philosophy of respect for input from all collaborators. Intangible aspects of the collaboration included camaraderie and strong team chemistry. LINX further benefited from being part of a discipline in which collaboration is a tradition, clear data-sharing and authorship guidelines, an approach that melded field experiments and modeling, and a shared collaborative goal in the form of a universal commitment to see the project and resulting data products through to completion

Elastic scattering with weakly bound projectiles

Possible effects of the break-up channel on the elastic scattering threshold anomaly has been investigated. We used the weakly bound 6,7Li nuclei, which is known to undergo break-up, as projectiles in order to study the elastic scattering on a 27Al target. In this contribution we present preliminary results of these experiments, which were analyzed in terms of the Optical Model and compared with other elastic scattering data using weakly bound nuclei as projectile. © 2007 American Institute of Physics.Fil:Figueira, J.M. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina.Fil:Fernández Niello, J.O. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina.Fil:Arazi, A. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina.Fil:Capurro, O.A. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina.Fil:Martí, G.V. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina.Fil:Pacheco, A.J. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina

Photonic microwave filter employing multimode optical sources and wideband chirped fibre gratings

A compact photonic microwave filter employing multimode lasers and wideband chirped fibre gratings is proposed. Experimental results are provided using a Fabry-Perot laser as a multimode optical source and a 4 nm chirped fibre grating with a group delay slope of nearly 400 ps/nm and single-mode optical fibre as the wideband dispersive media

Process Intensification with Bifunctional Heterogeneous Catalysts: Selective One-Pot Synthesis of 2′-Aminochalcones

2′-Aminochalcones of pharmaceutical and commercial interest have been obtained in high yields and selectivities through a one-pot process using a bifunctional heterogeneous catalyst bearing base and metal active sites. This is a physical mixture material formed by a high-surface-area MgO and Pt on TiO₂. The process involves as the first step the Claisen–Schmidt condensation between <i>o</i>-nitroacetophenone and benzaldehyde derivatives on the basic catalytic function. This is followed by a chemoselective hydrogenation of the nitro group in the presence of the carbonyl and double-bond carbon–carbon groups within the molecule. Using the bifunctional catalyst and the reaction system proposed here, it is possible to produce, under mild reaction conditions and short reaction times, 2′-aminochalcones with higher yields and selectivities than those obtained by conventional multistep methods

Characterization of the Methane–Graphene Hydrophobic Interaction in Aqueous Solution from <i>Ab Initio</i> Simulations

In this article, the interaction between a methane molecule and a graphene plane in liquid water has been characterized employing DFT-based free energy Molecular Dynamics calculations. This system represents a good model to understand the generic interaction between a small hydrophobic solute (methane molecule) and an extense hydrophobic surface (graphene plane). The structural and dynamical properties of graphene and methane hydration water are analyzed and found to be closely related to the main features of the potential of mean force. The results could be used in coarse-grained models to take into account the effect of the hydrophobic interaction in realistic systems relevant to experiment

A Novel Strategy to Study Electrostatic Effects in Chemical Reactions: Differences between the Role of Solvent and the Active Site of Chalcone Isomerase in a Michael Addition

The electrostatic behavior of active site residues in enzyme catalysis is quite different from that of water molecules in solution. To highlight the electrostatic differences between both environments, we propose a QM/MM strategy to study the role of the environment in chemical reactions. The novelty of the present communication is that free energy surfaces are generated by means of two distinguished reaction coordinates: a solute coordinate and the electrostatic potential created by the environment. This is applied to analyze the origin of catalysis in the transformation of a chalcone into a flavanone, a Michael addition that requires the desolvation of the nucleophile

Thermomechanical Response of a Representative Porin for Biomimetics

The thermomechanical response of Omp2a, a representative porin used for the fabrication of smart biomimetic nanomembranes, has been characterized using microcantilever technology and compared with standard proteins. For this purpose, thermally induced transitions involving the conversion of stable trimers to bigger aggregates, local reorganizations based on the strengthening or weakening of intermolecular interactions, and protein denaturation have been detected by the microcantilever resonance frequency and deflection as a function of the temperature. Measurements have been carried out on arrays of 8-microcantilevers functionalized with proteins (Omp2a, lysozyme and bovine serum albumin). To interpret the measured nanofeatures, the response of proteins to temperature has been also examined using other characterization techniques, including real time wide angle X-ray diffraction. Results not only demonstrate the complex behavior of porins, which exhibit multiple local thermal transitions before undergoing denaturation at temperatures higher than 105 °C, but also suggest a posttreatment to control the orientation of immobilized Omp2a molecules in functionalized biomimetic nanomembranes and, thus, increase their efficacy in ion transport