Dissipation by adhesion hysteresis in dynamic force microscopy

Power dissipation, as measured in dynamic force microscopy, is usually considered to be proportional to the energy lost in the contact process through the oscillation period. In the presence of adhesion hysteresis, the dissipation is not triggered in each oscillation and only a fraction of the cycles contributes to the dissipated power. We derive a simple analytical closed expression for the dissipated power versus the oscillation amplitude which is in good agreement with the results of numerical simulations. Our theoretical and numerical results predict the existence of two possible dissipation regimes. In the first one, the power dissipated is linear with the energy dissipated by the substrate as expected. In the second regime, a beating pattern appears, causing the fraction of cycles undergoing hysteresis to be inversely proportional to the energy dissipated. As a consequence, the measured power dissipation is a function of a characteristic dissipation length and it is not proportional to the energy lost in a single adhesion processThis work was supported by the Spanish MICINN Plan Nacional (Grant No. FIS2009-13430-C02-02) and by the Comunidad de Madrid Microseres-CM (Grant No. S2009/TIC-1476

Sobre las fuerzas capilares en microscopía de fuerzas: adhesión y disipación

Tesis doctoral inédita. Universidad Autónoma de Madrid, Facultad de Ciencias, Departamento de Física de la Materia Condensada. Fecha de lectura: 4/3/201

Decrease of the adhesion force with vapor pressure

Trabajo presentado a NanoSpain 2010 celebrado en Málaga del 23-26 Marzo, 2010. -- Incluye comunicación oral y póster.Experimental evidence of a monotonous decrease of the capillary forces between hydrophilic surfaces with increasing relative humidity from 0 to 100% is presented. In concordance with the results of a theoretical simulation, we identified the objects’ shape as the origin of different adhesion force vs. RH behaviours when treating with nanoscale objects. If the water neck is formed between a flat surface and a nanometric object presenting a truncated cone shape the adhesion force decreases with increasing vapour pressure. The variety of meniscus force behaviours found for different shapes emphasizes the importance of geometry in capillary phenomena at the nanometric scale.Peer reviewe

Climatic diversity and ecological descriptors of wild tomato species (Solanum sect. lycopersicon) and close related species (solanum sect. juglandifolia y sect. lycopersicoides) in Latin America

Conservation and sustainable use of species diversity require a description of the environment where they develop. The objectives were to determine ecological descriptors and climatic diversity of areas along the distribution range of 12 species of wild tomatoes (Solanum sect. Lycopersicon) and four wild species of phylogenetically related groups (Solanum sect. Juglandifolia and sect. Lycopersicoides), as well as their ecological similarity in Latin America. With 4228 selected tomato accessions and an environmental information system (EIS) composed of 21 climatic variables, diversity patterns of the distribution areas were identified for each species, as well as ecological descriptors through the use of geographic information systems (GIS). The contribution of climatic variables to the species geographical distribution was identified by principal component analysis (PCA), and similarity in species distribution as a function of the variables identified with cluster analysis (CA). Climatic characteristics and the environmental amplitude of wild tomatoes and related species along their distributional range were satisfactorily determined by ecological descriptors. Eleven climate types were identified, predominantly BSk (arid, steppe, cold), BWh (arid, desert, hot), and Cfb (temperate, no dry season, warm summer). PCA determined 10 most important variables were the most important for the geographical distribution. Six groups of species were identified according to CA and climatic distribution similarity. This approach has shown promissory applications for biodiversity conservation of valuable genetic resources for tomato crop breeding.Fil: Ramírez Ojeda, Gabriela. Universidad Autónoma de Chapingo; MéxicoFil: Peralta, Iris Edith. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto Argentino de Investigaciones de las Zonas Áridas. Provincia de Mendoza. Instituto Argentino de Investigaciones de las Zonas Áridas. Universidad Nacional de Cuyo. Instituto Argentino de Investigaciones de las Zonas Áridas; ArgentinaFil: Rodríguez Guzmán, Eduardo. Universidad de Guadalajara; MéxicoFil: Chávez Servia, José Luis. Instituto Politécnico Nacional; MéxicoFil: Sahagún Castellanos, Jaime. Universidad Autónoma de Chapingo; MéxicoFil: Rodríguez Pérez, Juan Enrique. Universidad Autónoma de Chapingo; Méxic

Assessing the expression of emotions in breast cancer survivors during the time of recovery: perspective from focus groups

[EN] Breast cancer has major public health implications, as it is the most frequent malignant tumor and the leading cause of cancer death in women. Survivors have many needs, including strategies to cope with the associated distress. We explore whether focus groups are useful for nurses to obtain information about the emotional state of breast cancer women, and develop strategies for coping with the stress that this disease entails. A qualitative study was carried out, involving 25 focus groups with 83 women treated for breast cancer, recruited from the local Breast Cancer Association (ALMOM). Four open-ended questions were employed, and 60-min discussions were carried out. They were transcribed, analyzed, coded, and the themes identified. Four major themes emerged, including “complex emotional evolution”, “emotional isolation”, “lack of information” and “inability to give advice”. Women admitted that this disease had been a stressful factor for them, causing emotional (anxiety, irritability, anger or guilt) and cognitive disorders (confusion, lack of concentration, forgetfulness). The use of focus groups in breast cancer survivors allows nurses to evaluate the expression of emotions in these women, and collect and share information about their feelings, thoughts and experiences, so that survivors can cope more easily with the stress related to their illness.S

Edaphoclimatic descriptors of wild tomato species (Solanum Sect. Lycopersicon) and closely related species (Solanum Sect. Juglandifolia and Sect. Lycopersicoides) in South America

Wild species related to cultivated tomato are essential genetic resources in breeding programs focused on food security to face future challenges. The ecogeographic analysis allows identifying the species adaptive ranges and most relevant environmental variables explaining their patterns of actual distribution. The objective of this research was to identify the diversity, ecological descriptors, and statistical relationship of 35 edaphoclimatic variables (20 climatic, 1 geographic and 14 edaphic variables) from 4,649 accessions of 12 wild tomato species and 4 closely related species classified in Solanum sect. Lycopersicon and clustered into four phylogenetic groups, namely “Lycopersicon group” (S. pimpinellifolium, S. cheesmaniae, and S. galapagense), “Arcanum group” (S. arcanum, S. chmielewskii, and S. neorickii), “Eriopersicon group” (S. habrochaites, S. huaylasense, S. corneliomulleri, S. peruvianum, and S. chilense), “Neolycopersicon group” (S. pennellii); and two phylogenetically related groups in Solanum sect. Juglandifolia (S. juglandifolium and S. ochranthum), and section Lycopersicoides (S. lycopersicoides and S. sitiens). The relationship between the climate and edaphic variables were determined by the canonical correlation analysis, reaching 89.2% of variation with the first three canonical correlations. The most significant climatic variables were related to humidity (annual evapotranspiration, annual precipitation, and precipitation of driest month) and physicochemical soil characteristics (bulk density, pH, and base saturation percentage). In all groups, ecological descriptors and diversity patterns were consistent with previous reports. Regarding edaphoclimatic diversity, 12 climate types and 17 soil units were identified among all species. This approach has promissory applications for biodiversity conservation and uses valuable genetic resources related to a leading crop.Fil: Ramírez Ojeda, Gabriela. Universidad Autónoma Chapingo; MéxicoFil: Peralta, Iris Edith. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto Argentino de Investigaciones de las Zonas Áridas. Provincia de Mendoza. Instituto Argentino de Investigaciones de las Zonas Áridas. Universidad Nacional de Cuyo. Instituto Argentino de Investigaciones de las Zonas Áridas; ArgentinaFil: Rodríguez Guzmán, Eduardo. Universidad de Guadalajara; MéxicoFil: Sahagún Castellanos, Jaime. Universidad Autónoma de Chapingo; MéxicoFil: Chávez Servia, José Luis. Instituto Nacional Politécnico; MéxicoFil: Medina Hinostroza, Tulio Cecilio. Gobierno del Perú. Ministerio del Ambiente; PerúFil: Rijalba Vela, Jorge Rodrigo. Universidad Pedro Ruiz Gallo; PerúFil: Vásquez Núñez, Leopoldo Pompeyo. Univeridad Pedro Ruiz Gallo; PerúFil: Rodríguez Pérez, Juan Enrique. Universidad Autónoma de Chapingo; Méxic

Phase contrast in simultaneous topography and recognition imaging

The operation of a force microscope in Simultaneous Topography and Recognition Imaging (TREC) mode is analyzed by means of numerical simulations. Both topography and recognition signals are analyzed by using a worm-like chain force as the specific interaction between the functionalized tip probe and the sample. The special feedback mechanism in this mode is shown to couple the phase signal to the presence of molecular recognition interactions even in absence of dissipation.M.F. acknowledges the hospitality offered to her by P. Hinterdorfer’s group at the Institute of Biophysics, University of Linz, during the completion of this work. This work was supported by the Spanish MICINN through the projects CTQ2005-07993-C0202/BQU, NAN2004-09125-C07-02, FIS2006-11170-C02-02, and FIS2005-05137, the Comunidad de Madrid Project Microseres-MC and by the EU IP “Molecular Imaging” (LSHG-CT-2003-503259). M.F. acknowledges financial support from the MICINN. M.K. acknowledges an I3P scholarship. M.L. acknowledges financial support from the MICINN through the Ramón y Cajal program.Peer reviewe