Estudio de la agregación de colorantes en películas mixtas ultrafinas

Uno de los objetivos de la química supramolecular ha sido y sigue siendo el desarrollo de métodos o estrategias para construir películas orgánicas ordenadas en estructuras bien definidas y de gran extensión. A escala nanoscópica, las propiedades físicas de estos sistemas moleculares se determinan mediante las relaciones entre su composición química, estructura y la organización de los materiales utilizados. En particular, cuando las moléculas que forman esos sistemas tienden a la agregación, también se ven afectadas sus características moleculares. De hecho, las consecuencias más importantes de la agregación molecular de colorantes orgánicos no son sólo los cambios químicos que se producen, sino principalmente los cambios detectados en las propiedades ópticas de las unidades cromóforas que interactúan entre sí. Ante este hecho es necesario buscar nuevas estrategias para la construcción de estructuras bi-dimensionales bien definidas en superficies (interfases) donde se facilite el control de la organización de los componentes de esos bloques moleculares. En este marco, la interfase aire-agua se constituye como interfase modelo donde la organización lateral es controlada mediante la preparación de películas delgadas. En estas películas ultrafinas mixtas, se seleccionan los componentes sobre la base de la formación de interacciones atractivas entre ellos, estableciendo la conexión lateral entre los mismos a través de la auto-agregación de los colorantes. Una estrategia para lograr esta conexión lateral es establecer un balance adecuado entre el tamaño de los grupos hidrofóbicos y los grupos polares. En este contexto mediante ciertos métodos experimentales se pueden formar películas con propiedades estructurales y ópticas bien definidas compuestas por mezclas de colorantes y lípidos. De esta forma, se preparan películas delgadas mixtas mediante el método de Langmuir en la interfase aire-agua y los métodos Langmuir-Blodgett (LB) y Langmuir-Schaeffer (LS) sobre soportes sólidos. Dichas películas mixtas están formadas por lípidos, tales como ácido 1,2-dimiristoil-sn-glicero-3-fosfato DMPA, ácido esteárico SA, y colorantes de carga opuesta como acridinas, cianinas y derivados de las cianinas, cuya estructura molecular les confiere un comportamiento anfifílico (cadenas alquílicas hidrófobas, grupo polar hidrofílico). Para poder estudiar y caracterizar estas películas delgadas mixtas es necesario disponer de técnicas que nos aporten información tanto de la organización de la parte polar, como de las cadenas alquílicas. No obstante, la mayoría de las técnicas de caracterización de monocapas Langmuir están centradas en el estudio y organización de las cadenas alquílicas que conforman el sistema, como la Espectroscopía infrarroja de absorción-reflexión con modulación de polarización (PM-IRRAS) , la técnica de Difracción de rayos X de incidencia rasante (GIXS) y la técnica de Reflectividad especular de rayos X (XRR), siendo más escasas aquellas que proporcionan información directa de la organización del grupo polar. Por todo ello es necesario desarrollar técnicas ópticas como la Microscopía de ángulo Brewster (BAM) y espectroscópicas como la Espectroscopía de Reflexión UV-visible bajo ángulo variable y luz polarizada (RAV) con el objetivo de obtener información útil acerca de la organización de las unidades moleculares que conforman la región polar y el uso de otras técnicas complementarias (fluorescencia, dicroismo circular), que aumenten el abanico de potenciales aplicaciones de estas películas. Por otra parte, es importante resaltar la utilización de técnicas de simulación en ordenador, así como el desarrollo de modelos teóricos y matemáticos en el sentido de validar y complementar los datos obtenidos experimentalmente

Theory of Caroli-de Gennes-Matricon analogs in full-shell nanowires

Full-shell nanowires are hybrid nanostructures consisting of a semiconducting core encapsulated in an epitaxial superconducting shell. When subject to an external magnetic flux, they exhibit the Little-Parks (LP) phenomenon of flux-modulated superconductivity, an effect connected to the physics of Abrikosov vortex lines in type-II superconductors. We show that full-shell nanowires can host subgap states that are a variant of the Caroli-de Gennes-Matricon (CdGM) states in vortices. These CdGM analogs are in fact shell-induced Van Hove singularities in propagating core subbands. We elucidate their structure, parameter dependence and behavior in tunneling spectroscopy through a series of models of growing complexity. We show through microscopic numerical simulations that they exhibit a characteristic skewness towards high magnetic fields inside non-zero LP lobes resulting from the interplay of three ingredients. First, core subbands exhibit a diamagnetic response, so that they disperse with flux depending on their generalized angular momentum. Second, the band bending at the core/shell interface induces a ring-like profile on the CdGM analog state wavefunctions with average radius smaller than the core radius. And last, degeneracy points emerge where all the CdGM Van Hove singularities coalesce. This happens when the flux threading each wavefunction is equal to an integer multiple of the flux quantum, a condition that shifts the degeneracy points away from the center of the LP lobes, skewing the CdGM analogs. Our analysis unlocks a transparent analytical description that allows to extract precise microscopic information about the nanowire by measuring the energy and skewness of CdGM analogs.Comment: 15 pages, 9 figure

Development and validation of a dynamic thermal model of a minibus using TRNSYS

[EN] The current paper presents a dynamic thermal model of a vehicle including two thermal zones, one for the front region (driver) and one for the back (passengers). The model, developed in TRNSYS, is able to predict the cabin¿s thermal behaviour under variable ambient temperatures and solar radiation. A minibus was used to validate the model using experimental data for ambient temperature, solar radiation and the indoor temperature of a minibus parked both inside and outside a garage in Torino (Italy). The proposed model accurately reproduces the warm-up and cool-down of the cabin. In addition, the model has been used to calculate the cooling load of the cabin during a summer day, and to quantify the thermal loads under variable ambient conditions. In future work, the model will be used to predict the dynamic performance of the A/C system in an urban driving cycle and to optimise the compressor control strategy.Daniela C. Vásconez-Núñez acknowledges the financial support provided by the CONVOCATORIA ABIERTA 2013-SEGUNDA FASE program, which was funded by the SENESCYT (Secretaría Nacional de Educación Superior, Ciencia, Tecnología e Innovación) (Grant No 2014-AR3R7463) of Ecuador.Vásconez-Núñez, DC.; Gonzálvez-Maciá, J.; Corberán, JM.; Payá-Herrero, J. (2018). Development and validation of a dynamic thermal model of a minibus using TRNSYS. International Journal of Vehicle Design. 77(1/2):87-107. https://doi.org/10.1504/IJVD.2018.098272S87107771/

Quantitative traits for the tail suspension test: automation, optimization, and BXD RI mapping

Immobility in the tail suspension test (TST) is considered a model of despair in a stressful situation, and acute treatment with antidepressants reduces immobility. Inbred strains of mouse exhibit widely differing baseline levels of immobility in the TST and several quantitative trait loci (QTLs) have been nominated. The labor of manual scoring and various scoring criteria make obtaining robust data and comparisons across different laboratories problematic. Several studies have validated strain gauge and video analysis methods by comparison with manual scoring. We set out to find objective criteria for automated scoring parameters that maximize the biological information obtained, using a video tracking system on tapes of tail suspension tests of 24 lines of the BXD recombinant inbred panel and the progenitor strains C57BL/6J and DBA/2J. The maximum genetic effect size is captured using the highest time resolution and a low mobility threshold. Dissecting the trait further by comparing genetic association of multiple measures reveals good evidence for loci involved in immobility on chromosomes 4 and 15. These are best seen when using a high threshold for immobility, despite the overall better heritability at the lower threshold. A second trial of the test has greater duration of immobility and a completely different genetic profile. Frequency of mobility is also an independent phenotype, with a distal chromosome 1 locus

The impact of age and comorbidity on the postoperative outcomes after emergency surgical management of complicated intra-abdominal infections

Age-adjusted Charlson Comorbidity Index (a-CCI) score has been used to weight comorbid conditions in predicting adverse outcomes. A retrospective cohort study on adult patients diagnosed with complicated intra-abdominal infections (cIAI) requiring emergency surgery was conducted in order to elucidate the role of age and comorbidity in this scenario. Two main outcomes were evaluated: 90-day severe postoperative complications (grade ≥ 3 of Dindo-Clavien Classification), and 90-day all-cause mortality. 358 patients were analyzed. a-CCI score for each patient was calculated and then divided in two comorbid categories whether they were ≤ or > to percentile 75 (= 4): Grade-A (0–4) and Grade-B (≥ 5). Univariate and multivariate regression analyses were performed, and the predictive validity of the models was evaluated by the area under the receiver operating characteristics (AUROC) curve. Independent predictors of 90-day severe postoperative complications were Charlson Grade-B (Odds Ratio [OR] = 3.49, 95% confidence interval [95%CI]: 1.86–6.52; p < 0.0001), healthcare-related infections (OR = 7.84, 95%CI: 3.99–15.39; p < 0.0001), diffuse peritonitis (OR = 2.64, 95%CI: 1.45–4.80; p < 0.01), and delay of surgery > 24 hours (OR = 2.28, 95%CI: 1.18–4.68; p < 0.02). The AUROC was 0.815 (95%CI: 0.758–0.872). Independent predictors of 90-day mortality were Charlson Grade-B (OR = 8.30, 95%CI: 3.58–19.21; p < 0.0001), healthcare-related infections (OR = 6.38, 95%CI: 2.72–14.95; p < 0.0001), sepsis status (OR = 3.98, 95%CI: 1.04–15.21; p < 0.04) and diffuse peritonitis (OR = 3.06, 95%CI: 1.29–7.27; p < 0.01). The AUROC for mortality was 0.887 (95%CI: 0.83–0.93). Post-hoc sensitivity analyses confirmed that the degree of comorbidity, estimated by using an age-adjusted score, has a critical impact on the postoperative course following emergency surgery for cIAI. Early assessment and management of patient’s comorbidity is mandatory at emergency setting

Organización lateral de monocapas mixtas

III Encuentro sobre Nanociencia y Nanotecnología de Investigadores y Tecnólogos Andaluce

A new role for green leaf volatile esters in tomato stomatal defense against Pseudomonas syringe pv. tomato

[EN] The volatile esters of (Z)-3-hexenol with acetic, propionic, isobutyric, or butyric acids are synthesized by alcohol acyltransferases (AAT) in plants. These compounds are differentially emitted when tomato plants are efficiently resisting an infection with Pseudomonas syringae pv. tomato. We have studied the defensive role of these green leaf volatile (GLV) esters in the tomato response to bacterial infection, by analyzing the induction of resistance mediated by these GLVs and the phenotype upon bacterial infection of tomato plants impaired in their biosynthesis. We observed that treatments of plants with (Z)-3-hexenyl propionate (HP) and, to a greater extent with (Z)-3-hexenyl butyrate (HB), resulted in stomatal closure, PR gene induction and enhanced resistance to the bacteria. HB-mediated stomatal closure was also effective in several plant species belonging to Nicotiana, Arabidopsis, Medicago, Zea and Citrus genus, and both stomatal closure and resistance were induced in HB-treated NahG tomato plants, which are deficient in salicylic acid (SA) accumulation. Transgenic antisense AAT1 tomato plants, which displayed a reduction of ester emissions upon bacterial infection in leaves, exhibited a lower ratio of stomatal closure and were hyper-susceptible to bacterial infection. Our results confirm the role of GLV esters in plant immunity, uncovering a SA-independent effect of HB in stomatal defense. Moreover, we identified HB as a natural stomatal closure compound with potential agricultural applications.This work was funded by Grant AICO/2017/048 from the Generalitat Valenciana and by Grant INNVAL10/18/005 from the Agencia Valenciana de la Innovacio (Spain). We would like to thank the Metabolomics Service of the IBMCP (Valencia, Spain), especially to Teresa Caballero for her excellent technical support in the VOCs quantification. We also thank Eduardo Moya for technical assistance.López-Gresa, MP.; Payá, C.; Ozáez-Martínez, M.; Rodrigo Bravo, I.; Conejero Tomás, V.; Klee, H.; Belles Albert, JM.... (2018). A new role for green leaf volatile esters in tomato stomatal defense against Pseudomonas syringe pv. tomato. Frontiers in Plant Science. 9:1-12. https://doi.org/10.3389/fpls.2018.01855S112