Sceloporus halli

Number of Pages: 3Integrative BiologyGeological Science

Inmunosensors més eficaços gràcies a l'oxigen

El desenvolupament de nous biosensors amb elevada sensibilitat i baix cost de producció ha estat impulsat gràcies a la nanotecnologia. Aquest treball analitza la fabricació d'immunosensors electroquímics basats en un compòsit de nanotubs de carboni (CNT) i matriu polimèrica (poliestirè), sotmès a un plasma d'oxigen per millorar el rendiment dels sensors.El desarrollo de nuevos biosensores de gran sensibilidad y bajo coste se está potenciando gracias a la nanotecnología. Este trabajo explora la fabricación de inmunosensores electroquímicos a partir de un compuesto de nanotubos de carbono y matriz polimérica (poliestireno), sometido a un plasma de oxígeno para mejorar el rendimiento de los sensores

Sceloporus megalepidurus

Number of Pages: 5Integrative BiologyGeological Science

The AC-120: The advanced commercial transport

The main objective of this design was to fulfill a need for a new airplane to replace the aging 100 to 150 passenger, 1500 nautical mile range aircraft such as the Douglas DC9 and Boeing 737-100 airplanes. After researching the future aircraft market, conducting extensive trade studies, and analysis on different configurations, the AC-120 Advanced Commercial Transport final design was achieved. The AC-120's main design features include the incorporation of a three lifting surface configuration which is powered by two turboprop engines. The AC-120 is an economically sensitive aircraft which meets the new FM Stage Three noise requirements, and has lower NO(x) emissions than current turbofan powered airplanes. The AC-120 also improves on its contemporaries in passenger comfort, manufacturing, and operating cost

A dry electrophysiology electrode using CNT arrays

We describe the concept of a dry electrode sensor for biopotential measurement applications (ENOBIO) designed to eliminate the noise and inconvenience associated to the use of electrolytic gel. ENOBIO uses nanotechnology to remove gel-related noise, as well as maintaining a good contact impedance to minimise interference noise. The contact surface of the electrode will be covered with an array/forest of carbon nanotubes and will also be tested with an Ag/AgCl coating to provide ionic-electronic transduction. The nanotubes are to penetrate the outer layers of the skin, the Stratum Corneum, improving electrical contact. We discuss requirements, skin properties, nanotube penetration and transduction, noise sources, prototype design logic and biocompatibility. A future paper will report test results.Comment: Submitted to Sensors and Actuators, Proceedings of Eurosensors XIX, Barcelona, Spain, 2005. Figure 2 corrected, references correcte

ENOBIO - First Tests of a Dry Electrophysiology Electrode Using Carbon Nanotubes

We describe the development and first tests of ENOBIO, a dry electrode sensor concept for biopotential applications. In the proposed electrodes the tip of the electrode is covered with a forest of multi-walled Carbon Nanotubes (CNTs) that can be coated with Ag/AgCl to provide ionic–electronic transduction. The CNT brushlike structure is to penetrate the outer layers of the skin improving electrical contact as well as increase the contact surface area. In this paper we report the results of the first tests of this concept—immersion on saline solution and pig skin signal detection. These indicate performance on a par with state of the art researchoriented wet electrodes.</p

Análisis del comercio de mango en el marco del T-MEC, un análisis de competitividad

Mangifera indica L., generally known as mango, is a product in demand throughout the world and especially in the US. The lack of knowledge of the commercial positioning within the framework of the T-MEC of the Mexican mango is a significant problem to study due to the relevance of the product. The goal of this study was to examine the commercial competitiveness of the Mexican mango within the US trade in the framework of the USMCA, through the determination of logarithmic growth rates using data exports, imports, and mango production, as well as commercial competitiveness indices during the period 1994-2020. As a methodology, a data set of production, exports, and imports in tons and dollars was documented. The sources consulted were TRADEMAP, SIAP, USDA, and FAOSTAT in the period 1994-2020 and trade competitiveness indices were calculated. The results indicate that exports grew 361%, and imports grew, but they continue to be insignificant; the indicators showed a positive situation in general, the relative trade balance index was very close to 1, the tradability index was 0.13 on average, the degree of export openness was positive in all years, imports presented in the degree of penetration values ​​very close to 0. We conclude that the demand of the United States grows in greater proportion than the Mexican supply. Therefore, the increases in national production are expected to be absorbed by the US market, leading to a significant and sustained increase in competitiveness.  El Mangifera indica L., conocida generalmente como mango, es un producto demandado en el mundo y especialmente en Estados Unidos. El desconocimiento del posicionamiento comercial en el marco del t-mec del mango mexicano resulta una problemática significativa a estudiar, debido a la relevancia del producto. Se tiene como objetivo examinar la competitividad comercial del mango mexicano dentro del comercio estadounidense en el marco del t-mec, determinando tasas de crecimiento logarítmicas usando exportaciones, importaciones, índices de competitividad comercial y producción del mango de 1994 al 2020. Como metodología, se documentaron datos de producción, exportaciones e importaciones en toneladas y dólares. Se consultaron fuentes como Trademap, siap, usda y fao de 1994 al 2020 y se calcularon índices de competitividad comercial. Los resultados señalan que las exportaciones crecieron 361 %, las importaciones crecieron, pero continúan siendo poco significativas; los indicadores demostraron positividad general, el índice de la balanza comercial relativa fue cercano a 1, el índice de transabilidad fue de 0,13 en promedio, el grado de apertura exportadora fue positivo en dicho periodo y las importaciones presentaron en el grado de penetración valores cercanos a 0. Así, se concluye que la demanda de los Estados Unidos crece en mayor proporción que la oferta mexicana. A futuro, los aumentos de producción nacional serán absorbidos por el mercado estadounidense, por lo que se prevé un aumento significativo y sostenido de la competitividad

Simulación de la onda de avenida por ruptura de tanque de enfriamiento

Se llev&oacute; a cabo la simulaci&oacute;n de la ruptura del borde de un tanque de enfriamiento usando dos m&eacute;todos: Uno de vol&uacute;menes finitos denominado CARPA y un algoritmo en diferencias finitas centradas. El algoritmo en vol&uacute;menes finitos CARPA utilizado con el pre y post procesador GiD mostr&oacute; ser una herramienta muy poderosa en la animaci&oacute;n de planicies de inundaci&oacute;n, &uacute;tiles en la interpretaci&oacute;n de resultados tanto en el espacio como en el tiempo, para la protecci&oacute;n civil, as&iacute; como para definir las posibles zonas afectadas debido a fen&oacute;menos como el de la ruptura de bordo

Exceptional oxidation activity with size-controlled supported gold clusters of low atomicity

[EN] The catalytic activity of gold depends on particle size, with the reactivity increasing as the particle diameter decreases. However, investigations into behaviour in the subnanometre regime (where gold exists as small clusters of a few atoms) began only recently with advances in synthesis and characterization techniques. Here we report an easy method to prepare isolated gold atoms supported on functionalized carbon nanotubes and their performance in the oxidation of thiophenol with O-2. We show that single gold atoms are not active, but they aggregate under reaction conditions into gold clusters of low atomicity that exhibit a catalytic activity comparable to that of sulfhydryl oxidase enzymes. When clusters grow into larger nanoparticles, catalyst activity drops to zero. Theoretical calculations show that gold clusters are able to activate thiophenol and O-2 simultaneously, and larger nanoparticles are passivated by strongly adsorbed thiolates. The combination of both reactants activation and facile product desorption makes gold clusters excellent catalysts.Financial support from the Spanish Science and Innovation Ministry (Consolider Ingenio 2010-MULTICAT CSD2009-00050, Subprograma de apoyo a Centros y Universidades de Excelencia Severo Ochoa SEV 2012 0267, MAT2011-28009 and MAT2010-20442 projects) and Xunta de Galicia (Grupos Ref.Comp.2010/41) is acknowledged. M.J.Y. and E. L. acknowledge the support of the National Centre for Research Resources (5 G12RR013646-12) and the National Institute on Minority Health and Health Disparities (G12MD007591) from the National Institutes of Health and of the National Science Foundation for support with grants DMR-1103730 and PREM: NSF PREM Grant # DMR 0934218. We also acknowledge the support of Consejo Nacional De Ciencia y Tecnologia. J.N. expresses his gratitude to Consejo Superior de Investigaciones Cientificas for a JAE Fellowship.Corma Canós, A.; Concepción Heydorn, P.; Boronat Zaragoza, M.; Sabater Picot, MJ.; Navas Escrig, J.; Yacaman, MJ.; Larios, E.... (2013). Exceptional oxidation activity with size-controlled supported gold clusters of low atomicity. Nature Chemistry. 5(9):775-781. https://doi.org/10.1038/NCHEM.1721S77578159Hughes, M. D. et al. Tunable gold catalysts for selective hydrocarbon oxidation under mild conditions. Nature 437, 1132–1135 (2005).Hashmi, A. S. K. & Hutchings, G. J. Gold catalysis. Angew. Chem. Int. Ed. 45 7896–7936 (2006).Corma, A. & Garcia, H. Supported gold nanoparticles as catalysts for organic reactions. Chem. Soc. Rev. 37, 2096–2126 (2008).Haruta, M. Size- and support-dependency in the catalysis of gold. Catal. Today 36, 153–166 (1997).López, N. et al. On the origin of the catalytic activity of gold nanoparticles for low-temperature CO oxidation. J. Catal. 223, 232–235 (2004).Hutchings, G. J. Catalysis by gold. Catal. Today 100, 55–61 (2005).Chen, M. S. & Goodman, D. W. Catalytically active gold: from nanoparticles to ultrathin films. Acc. Chem. Res. 39, 739–746 (2006).Risse, Th., Shaikhutdinov, Sh., Nilius, N., Sterrer, M. & Freund, H. J. Gold supported on thin oxide films: from single atoms to nanoparticles. Acc. Chem. Res. 41, 949–956 (2008).Liu, Y., Tsunoyama, H., Akita, T., Xie, S. & Tsukuda, T. Aerobic oxidation of cyclohexane catalysed by size-controlled Au clusters on hydroxyapatite: size effect in the sub-2 nm regime. ACS Catal. 1, 2–6 (2011).Huang, J. et al. Propene epoxidation with O2 and H2: identification of the most active gold clusters. J. Catal. 278, 8–15 (2011).Haruta, M. et al. Low-temperature oxidation of CO over gold supported on TiO2, α-Fe2O3, and Co3O4 . J. Catal. 144, 175–192 (1993).Tsunoyama, H., Ichikuni, N., Sakurai, H. & Tsukuda, T. Effect of electronic structures of Au clusters stabilized by poly(N-vinyl-2-pyrrolidone) on aerobic oxidation catalysis. J. Am. Chem. Soc. 131, 7086–7093 (2009).Herzing, A. A., Kiely, C. J., Carley, A. F., Landon, P. & Hutchings, G. J. Identification of active gold nanoclusters on iron oxide supports for CO oxidation. Science 321, 1331–1332 (2008).Lupini A. R., Veith, G. M., Dudney, J. & Pennycook, S. J. Understanding catalyst stability through aberration-corrected STEM. Microsc Microanal. 15, 1408–1409 (2009).Allard, L. F. et al. Evolution of gold structure during thermal treatment of Au/FeOx catalysts revealed by aberration-corrected electron microscopy. J. Electron Microsc. 58, 199–212 (2009).Uzun, A., Ortalan, V., Hao, Y., Browning, N. D. & Gates, B. C. Imaging gold atoms in site-isolated MgO-supported mononuclear gold complexes. J. Phys. Chem. C 113, 16847–16849 (2009).Lu, J., Aydin, C., Browning, N. D. & Gates, B. C. Imaging isolated gold atom catalytic sites in zeolite NaY. Angew. Chem. 51, 5842–5846 (2012).Yoon, B., Häkkinen, H. & Landman, U. Interaction of O2 with gold clusters: molecular and dissociative adsorption. J. Phys. Chem. A 107, 4066–4071 (2003).Lang, S. M., Bernhardt, T. M., Barnett, R. N., Yoon, B. & Landman, U. Hydrogen-promoted oxygen activation by free gold cluster cations. J. Am. Chem. Soc. 131, 8939–8951 (2009).Hagen, J. et al. Coadsorption of CO and O2 on small free gold cluster anions at cryogenic temperatures: model complexes for catalytic CO oxidation. Phys. Chem. Chem. Phys. 4, 1707–1709 (2002).Molina, L. M., Lesarri, A. & Alonso, J. A. New insights on the reaction mechanism for CO oxidation on Au catalysts. Chem. Phys. Lett. 468, 201–204 (2009).Joshi, A. M., Delgass, W. N. & Thomson, K. T. Comparison of the catalytic activity of Au3, Au4+, Au5 and Au5− in the gas-phase reaction of H2 and O2 to form hydrogen peroxide: a density functional theory investigation. J. Phys. Chem. B 109, 22392–22406 (2005).Lee, S. et al. Selective propene epoxidation on immobilized Au6–10 clusters: the effect of hydrogen and water on activity and selectivity. Angew. Chem. Int. Ed. 48, 1467–1471 (2009).Guzman, J. & Gates, B. C. Structure and reactivity of a mononuclear gold-complex catalyst supported on magnesium oxide. Angew. Chem. Int. Ed. 42, 690–693 (2003).Robinson, P. S. D., Khairallah, G. N., da Silva, G., Lioe, H. & O'Hair, R. A. J. Gold-mediated C–I bond activation of iodobenzene. Angew. Chem. Int. Ed. 51, 3812–3817 (2012).Jia, C. J. & Schüth, F. Colloidal metal nanoparticles as a component of designed catalyst. Phys. Chem. Chem. Phys. 13, 2457–2487 (2011).Tran, M. L., Zvyagin, A. V. & Plakhotnik, T. Synthesis and spectroscopic observation of dendrimer-encapsulated gold nanoclusters. Chem. Commun. 2400–2401 (2006).Ledo-Suárez, A. et al. Facile synthesis of stable subnanosized silver clusters in microemulsions. Angew. Chem. Int. Ed. 46, 8823–8827 (2007).Turner, M. et al. Selective oxidation with dioxygen by gold nanoparticle catalysts derived from 55-atom clusters. Nature 454, 981–983 (2008).Liu, Y. M., Tsunoyama, H., Akita, T. & Tsukuda, T. Chem. Commun. 46, 550–552 (2010).Shichibu, Y. & Konishi, K. HCl-induced nuclearity convergence in diphosphine-protected ultrasmall gold clusters: a novel synthetic route to ‘magic-number’ Au13 clusters. Small 6, 1216–1220 (2010).Xie, S., Tsunoyama, H., Kurashige, W., Negishi, Y. & Tsukuda, T. Enhancement in aerobic alcohol oxidation catalysis of Au25 clusters by single Pd atom doping. ACS Catal. 2, 1519–1523 (2012).Sanchez, A. et al. When gold is not noble: nanoscale gold catalysts. J. Phys. Chem. A 103, 9573–9578 (1999).Hoober, K. L. & Thorpe, C. Egg white sulfhydryl oxidase: kinetic mechanism of the catalysis of disulfide bond formation. Biochemistry 38, 3211–3217 (1999).Jaje, J. et al. A flavin-dependent sulfhydryl oxidase in bovine milk. Biochemistry 46, 13031–13040 (2007).Dumont, E., Michel, C. & Sautet, P. Unraveling gold(I)-specific action towards peptidic disulfide cleavage: a DFT investigation. ChemPhysChem 12, 2596–2603 (2011).Barton, D. G. & Podkolzin, S. G. Kinetic study of a direct water synthesis over silica-supported gold nanoparticles. J. Phys. Chem. B 109, 2262–2274 (2005).Ntainjua, E. N. et al. The role of the support in achieving high selectivity in the direct formation of hydrogen peroxide. Green Chem. 10, 1162–1169 (2008).Jadzinsky, P. D., Calero, G., Ackerson, C. J., Bushnell, D. A. & Kornberg, R. D. Structure of a thiol monolayer-protected gold nanoparticle at 1.1 Å resolution. Science 318, 430–433 (2007).Häkkinen, H. The gold–sulfur interface at the nanoscale. Nature Chem. 4, 443–455 (2012).Alves, L. et al. Synthesis and stabilization of subnanometric gold oxide nanoparticles on multiwalled carbon nanotubes and their catalytic activity. J. Am. Chem. Soc. 133, 10251–10261 (2011).Santiago-González, B. et al. One step synthesis of the smallest photoluminescent and paramagnetic PVP-protected gold atomic clusters. Nano Lett. 10, 4217–4221 (2010).Becke, A. D. Density-functional thermochemistry. III. The role of exact exchange. J. Chem. Phys. 98, 5648–5652 (1993).Lee, C., Yang, W. & Parr, R. G. Development of the Colle–Salvetti correlation-energy formula into a functional of the electron density. Phys. Rev. B 37, 785–789 (1988).Frisch, M. J. et al. Gaussian 03, Revision B.04 (Gaussian, 2003).McLean A. D. & Chandler G. S. Contracted Gaussian basis sets for molecular calculations. I. Second row atoms, Z = 11–18. J. Chem. Phys. 72 5639–5648 (1980).Krishnan, R., Binkley, J. S., Seeger, R. &. Pople, J. A. Self-consistent molecular orbital methods. XX. A basis set for correlated wave functions. J. Chem. Phys. 72 650–654 (1980).Hay P. J. & Wadt, W. R. Ab initio effective core potentials for molecular calculations. Potentials for the transition metal atoms Sc to Hg. J. Chem. Phys. 82, 270–283 (1985).Reed, A. E., Weinstock, R. B. & Weinhold, F. Natural population analysis. J. Chem. Phys. 83, 735–747 (1985)