2,523 research outputs found

    Thinking Outside the Blue Box: Induced Fit within a Unique Self-Assembled Polycationic Cyclophane

    Get PDF
    This document is the Accepted Manuscript version of a Published Work that appeared in final form in Journal of the American Chemical Society.[Abstract] We present herein the development of a new polycationic molecular receptor, inspired by the ubiquitous cyclobis(paraquat-p-phenylene)cyclophane (“blue box”). Our analogue, the “white box”, has been easily self-assembled on a preparative scale in water, using a template-assisted process by acyl hydrazone bonding of complementary bis(pyridinium)xylylene tweezers, followed by kinetic trapping of the empty receptor. The obtained macrocycle was found to display a marked pH responsiveness in water, because of an abnormal acidity of the amide protons within its structure. Consequently, and because of the concurrence of rotational isomerism under acidic conditions (fixed at higher pH values), the compound was found to display a dual behavior as a conformationally locked/flexible molecular host, being able to recognize appropriate aromatic substrates, in a lock and key or induced fit fashion, by a conjunction of π–π, C–H···π, and, crucially, the hydrophobic effect.This research was supported by the Ministerio de Economía y Competitividad (MINECO FEDER, Grant CTQ2016-75629-P

    Corinth terraces re-visited: Improved paleoshoreline determination using Pleiades-DEMs

    Get PDF
    International audienceThe newest generation of satellites have greatly improved the capabilities of optical imagery over the last decade. Ground resolution has increased by one order of magnitude (to sub-metric pixel images), and improved sensors allow images to be located with an absolute accuracy of within a few meters. Better-resolved images facilitate refined tectonic studies of faults, basins, terraces, and other geomorphic features as it provides the opportunity to extract detailed topographic information. We have developed high-resolution digital elevation models (DEMs) in eight locations in Greece from tri-stereo satellite images acquired by the new Pleiades platform of CNES. With 0.5m resolution, these DEMs are state-of-the-art in comparison to previous DEMs made from satellite imagery. In this study we explore the potential of one of these DEMs, in the eastern Gulf of Corinth, for the analysis of a flight of marine terraces

    A convenient synthesis of new 6-substituted purinylcarbanucleosides on cyclopenta[b]thiophene

    Get PDF
    The 12th International Electronic Conference on Synthetic Organic Chemistry session Bioorganic Chemistry and Natural ProductsThe first members of a new family of heterocarbobicyclic nucleoside analogues have been synthesized from the cis/trans mixture of (4-amino-5,6-dihydro-4H-cyclopenta[b]thiophen-6-yl)methanols cis/trans-7. The separation of cis and trans intermediates during preparation of the 6-chloropurine derivatives allowed separate preparation of the purine heterocarbanucleosides cis-10 and trans-11, from which cis-(12-14) and trans-(16-18) were obtained by replacement of the 6-chloro substituent with amino, hydroxy and cyclopropylamino groups. Additionally, the 6-phenyl-purinyl analogues cis-15 and trans-19 were prepared from cis-10 and trans-11 using Suzuki-Miyaura methodologyThe authors thank the Xunta de Galicia for financial support under project PGIDIT02BTF20305P

    Desarrollo y validación experimental de una metodología para estudiar la propagación de grietas por fatiga en metales

    Get PDF
    La presencia y propagación de grietas en estructuras y componentes es un reto para sectores industriales como el oil&gas, energía eólica o nuclear. El presente estudio resume la investigación realizada para desarrollar y validar un procedimiento basado en el método de los Elementos Finitos capaz de simular la propagación de grietas tridimensionales. La investigación comprende una parte experimental donde se ha caracterizado la velocidad de propagación de fisuras frente a fatiga del acero grado R5, utilizado en cadenas de fondeo offshore. Para ello se ha determinado la Ley de Paris del material mediante el ensayo de una probeta de flexión en tres puntos. Asimismo, se ha realizado un estudio estadístico para estimar la incertidumbre en la velocidad de propagación de la grieta. Los resultados experimentales han sido empleados como inputs del modelo numérico desarrollado en ANSYS APDL. Este algoritmo permite evaluar numéricamente los parámetros de la mecánica de la fractura en el frente de fisura durante su crecimiento. Esta información alimenta un algoritmo iterativo que proporciona el avance del frente de fisura. Finalmente, se ha realizado un estudio de sensibilidad para evaluar el efecto del tamaño del mallado en los resultados.The existence and propagation of cracks in structures and components is a challenge for industrial sectors such as oil & gas, wind or nuclear. The present study summarizes the research carried out to develop and validate a procedure, based on the finite element method, able to simulate the propagation of three-dimensional cracks. This research comprises an experimental part where the fatigue crack propagation rate of the grade R5 steel, widely used in offshore mooring chains, has been characterized. For this purpose, the Paris Law of the material has been determined by testing a three point bending specimen. Furthermore, a statistical study to estimate the uncertainty in the crack propagation rate was carried out. The experimental results have been used as inputs for the numerical model developed in ANSYS APDL. This algorithm allows numerical evaluating the fracture mechanics parameters in the crack front during its growth. This information feedbacks an iterative algorithm that provides the crack front growth. Finally, a sensitivity study was carried out to evaluate the effect of the meshing size on the results

    Relación entre las concentraciones de polen aéreo de Artemisia, Chenopodiaceae, Plantago y Taraxacum y la prevalencia de polinosis en estudiantes universitarios de León

    Get PDF
    XV lnternational A.P.L.E. Symposium of Palynolog

    “Skills for pills”: The dialectical-behavioural therapy skills training reduces polypharmacy in borderline personality disorder

    Get PDF
    Objective: Polypharmacy and overprescription of off-label medications are common in patients with borderline personality disorder (BPD). The aim of the present naturalistic study was to explore whether the skills training module of dialectical-behavioural therapy (DBT) can reduce polypharmacy in these patients in routine clinical practice. Methods: Retrospective, observational study of 377 patients with a primary diagnosis of BPD consecutively admitted to the BPD outpatient unit from 2010 through 2020. All patients were invited to participate in the DBT skills training module (DBT-ST). DBT-ST participants (n = 182) were compared with a control group who did not participate in DBT-ST (n = 195). Pre-post intervention changes in medication load and use of antidepressants, benzodiazepines, mood stabilizers, and antipsychotics were evaluated. Results: At baseline, most patients (84.4%) were taking at least one medication and 46.9% were on polypharmacy. Compared to controls, patients in the DBT-ST group presented a significant reduction in the number of medications (2.67–1.95 vs. 2.16–2.19; p < 0.001), medication load (4.25–3.05 vs. 3.45–3.48; p < 0.001), use of benzodiazepines (54.4%–27.5% vs. 40%–40.5%; p < 0.001), mood stabilizers (43.4%–33% vs. 36.4%–39.5%; p < 0.001), and antipsychotics (36.3%–29.1% vs. 34.4%–36.9%; p < 0.001). Conclusions: These findings suggest that patients with BPD can benefit from the DBT-ST module, which may reduce the medication load, particularly of sedatives. The results suggest that DBT-ST may be useful to treat overmedication in patients with BPD and could help to promote “deprescription” in clinical practice.This study was supported by Centro de Investigación Biomédica en Red de Salud Mental (CIBERSAM). The authors would like to thank Bradley Londres for professional English language editing

    Strain-balanced type-II superlattices for efficient multi-junction solar cells

    Get PDF
    Multi-junction solar cells made by assembling semiconductor materials with different bandgap energies have hold the record conversion efficiencies for many years and are currently approaching 50%. Theoretical efficiency limits make use of optimum designs with the right lattice constant-bandgap energy combination, which requires a 1.0–1.15 eV material lattice-matched to GaAs/Ge. Nevertheless, the lack of suitable semiconductor materials is hindering the achievement of the predicted efficiencies, since the only candidates were up to now complex quaternary and quinary alloys with inherent epitaxial growth problems that degrade carrier dynamics. Here we show how the use of strain-balanced GaAsSb/GaAsN superlattices might solve this problem. We demonstrate that the spatial separation of Sb and N atoms avoids the ubiquitous growth problems and improves crystal quality. Moreover, these new structures allow for additional control of the effective bandgap through the period thickness and provide a type-II band alignment with long carrier lifetimes. All this leads to a strong enhancement of the external quantum efficiency under photovoltaic conditions with respect to bulk layers of equivalent thickness. Our results show that GaAsSb/GaAsN superlattices with short periods are the ideal (pseudo)material to be integrated in new GaAs/Ge-based multi-junction solar cells that could approach the theoretical efficiency limit

    Prediction of adverse neonatal outcome at admission for early-onset preeclampsia with severe features

    Full text link
    Preeclampsia remains the leading cause of maternal morbidity and mortality. Consequently, research has focused on validating tools to predict maternal outcomes regarding clinical and biochemical features from the maternal compartment. However, preeclampsia also leads to neonatal complications due to placental insufficiency and prematurity, being the early-onset type associated with the poorest outcome. Hence, it is imperative to study whether these existing tools can predict adverse neonatal outcome.To assess the predictive value for adverse neonatal outcome of Doppler ultrasound, angiogenic factors and multi-parametric risk-score models in women with early-onset severe preeclampsia.This is a prospective cohort study of consecutive singleton pregnancies complicated by early-onset (developed before 34 week's gestation) severe preeclampsia.63 women with early-onset severe preeclampsia, 18 (28.6%) presented an adverse neonatal outcome. Placental growth factor (PlGF) showed the best discrimination between neonatal outcomes among angiogenic factors. PREP-L score is a multi-parametric risk-score for the prediction of complications in early-onset preeclampsia which includes maternal characteristics and clinical and analytical data obtained at admission. Good predictive values for the prediction of neonatal complications were found with the combination of PREP-L score with advanced Doppler (AUC ROC 0.9 95% CI 0.82-0.98]) and with PlGF levels (AUC ROC 0.91 [95% CI 0.84-0.98]).The combination of maternal risk scoring (PREP-L score) with angiogenic factors or fetal Doppler ultrasound at the time of diagnosis of early-onset preeclampsia with severe features performs well in predicting adverse neonatal outcome.Copyright © 2023 International Society for the Study of Hypertension in Pregnancy. Published by Elsevier B.V. All rights reserved

    Spatial modeling for low pathogenicity avian influenza virus at the interface of wild birds and backyard poultry

    Get PDF
    Low pathogenicity avian influenza virus (LPAIV) is endemic in wild birds and poultry in Argentina, and active surveillance has been in place to prevent any eventual virus mutation into a highly pathogenic avian influenza virus (HPAIV), which is exotic in this country. Risk mapping can contribute effectively to disease surveillance and control systems, but it has proven a very challenging task in the absence of disease data. We used a combination of expert opinion elicitation, multicriteria decision analysis (MCDA), and ecological niche modeling (ENM) to identify the most suitable areas for the occurrence of LPAIV at the interface between backyard domestic poultry and wild birds in Argentina. This was achieved by calculating a spatially‐explicit risk index. As evidenced by the validation and sensitivity analyses, our model was successful in identifying high‐risk areas for LPAIV occurrence. Also, we show that the risk for virus occurrence is significantly higher in areas closer to commercial poultry farms. Although the active surveillance systems have been successful in detecting LPAIV‐positive backyard farms and wild birds in Argentina, our predictions suggest that surveillance efforts in those compartments could be improved by including high‐risk areas identified by our model. Our research provides a tool to guide surveillance activities in the future, and presents a mixed methodological approach which could be implemented in areas where the disease is exotic or rare and a knowledge‐driven modeling method is necessary
    corecore