Estudio sobre imidazoles sulfo-funcionalizados para aplicaciones catalíticas en síntesis orgánica

En este trabajo se recopilan los resultados del estudio llevado a cabo sobre la elaboración del 1,3-bis(sulfometil)imidazol (bsmim) y su aplicación como catalizador en reacciones donde se obtienen como producto derivados de quinolina y acridina. En primer lugar, se realizaron ensayos para la síntesis de la sal de imidazolio, variando las condiciones de temperatura, tiempo y equivalentes de los reactivos, con el fin de poder aislar la mayor cantidad de bsmim posible. Posteriormente se procedió a utilizar el bsmim para catalizar las reacciones que se mostraran más adelante. Se obtuvieron una serie de derivados de quinolina con buenos rendimientos en general, y de algunos otros productos no se pudo aislar suficiente cantidad

Low-Cost Piezoelectric Sensors for Time Domain Load Monitoring of Metallic Structures During Operational and Maintenance Processes

The versatility of piezoelectric sensors in measurement techniques and their performance in applications has given rise to an increased interest in their use for structural and manufacturing component monitoring. They enable wireless and sensor network solutions to be developed in order to directly integrate the sensors into machines, fixtures and tools. Piezoelectric sensors increasingly compete with strain-gauges due to their wide operational temperature range, load and strain sensing accuracy, low power consumption and low cost. This research sets out the use of piezoelectric sensors for real-time monitoring of mechanical strength in metallic structures in the ongoing operational control of machinery components. The behaviour of aluminium and steel structures under flexural strength was studied using piezoelectric sensors. Variations in structural behaviour and geometry were measured, and the load and μstrains during operational conditions were quantified in the time domain at a specific frequency. The lead zirconium titanate (PZT) sensors were able to distinguish between material types and thicknesses. Moreover, this work covers frequency selection and optimisation from 20 Hz to 300 kHz. Significant differences in terms of optimal operating frequencies and sensitivity were found in both structures. The influence of the PZT voltage applied was assessed to reduce power consumption without signal loss, and calibration to μstrains and loads was performed.This research was funded by Basque Government, grant number KK-2019/00051-SMARTRESNAK and by the European Commission, grant number 869884- RECLAIM

A new upper bound for 3-SAT

We show that a randomly chosen 3-CNF formula over n variables with clauses-to-variables ratio at least 4.4898 is, as n grows large, asymptotically almost surely unsatisfiable. The previous best such bound, due to Dubois in 1999, was 4.506. The first such bound, independently discovered by many groups of researchers since 1983, was 5.19. Several decreasing values between 5.19 and 4.506 were published in the years between. The probabilistic techniques we use for the proof are, we believe, of independent interest.Comment: 20 page

A New Approach for Eliminating the Spurious States in Recurrent Neural Networks

As is well known, the Convergence Theorem for the Recurrent Neural Networks, is based in Lyapunov ́s second method, which states that associated to any one given net state, there always exist a real number, in other words an element of the one dimensional Euclidean Space R, in such a way that when the state of the net changes then its associated real number decreases. In this paper we will introduce the two dimensional Euclidean space R2, as the space associated to the net, and we will define a pair of real numbers ( x, y ) , associated to any one given state of the net. We will prove that when the net change its state, then the product x ⋅ y will decrease. All the states whose projection over the energy field are placed on the same hyperbolic surface, will be considered as points with the same energy level. On the other hand we will prove that if the states are classified attended to their distances to the zero vector, only one pattern in each one of the different classes may be at the same energy level. The retrieving procedure is analyzed trough the projection of the states on that plane. The geometrical properties of the synaptic matrix W may be used for classifying the n-dimensional state- vector space in n classes. A pattern to be recognized is seen as a point belonging to one of these classes, and depending on the class the pattern to be retrieved belongs, different weight parameters are used. The capacity of the net is improved and the spurious states are reduced. In order to clarify and corroborate the theoretical results, together with the formal theory, an application is presented

Relapses and obstetric outcomes in women with multiple sclerosis planning pregnancy

Abstract Objective To evaluate the effect of discontinuation of different disease-modifying therapies (DMTs) before pregnancy with respect to the occurrence of relapses and pregnancy outcomes. Methods Women with multiple sclerosis who desire to bear children were followed prospectively. Demographic data, clinical characteristics, and the information on the use of DMTs were collected. A multivariate analysis was used to assess the relationship between relapses and the prior use of different DMTs. Results The present study assessed 75 consecutive pregnancy plans (66 women), 65 of which resulted in pregnancy. The mean age of the participants was 32.1 ± 4.2 years, and the mean disease duration was 6.1 ± 4.2 years. No relapses before pregnancy were reported in the group of women who maintained their DMT until pregnancy confirmation, while 14 relapses were reported in 12/42 women (29%) who discontinued DMT before pregnancy. During pregnancy, patients on natalizumab or fingolimod before pregnancy had a higher rate of relapses. Most women restarted their previous DMT after delivery within the first trimester. The relapse rate in postpartum was 0.07. Conclusions Disease-modifying therapies received influences the risk of relapse and disease progression from women who are planning pregnancy. The risk of relapse during pregnancy was significantly higher in the group of women treated with natalizumab or fingolimod compared to the group of women treated with interferon beta or glatiramer acetate. The postpartum risk of relapses was lower than that found in previous reports