Gating-induced large aqueous volumetric remodeling and aspartate tolerance in the voltage sensor domain of Shaker K+ channels

Indexación: Scopus.ACKNOWLEDGMENTS. We thank Chris Lingle and Yu Zhou (Washington University) for critical reading of the manuscript and Victoria Prado for Xenopus care and oocyte preparation. We also thank Millennium Scientific Initiative P029-022-F. This work was supported by Fondecyt Postdoctoral Grants 3170599 (to I.D.-F.) and 3160321 (to H.M.).Neurons encode electrical signals with critically tuned voltage-gated ion channels and enzymes. Dedicated voltage sensor domains (VSDs) in these membrane proteins activate coordinately with an unresolved structural change. Such change conveys the transmembrane translocation of four positively charged arginine side chains, the voltage-sensing residues (VSRs; R1–R4). Countercharges and lipid phosphohead groups likely stabilize these VSRs within the low-dielectric core of the protein. However, the role of hydration, a sign-independent charge stabilizer, remains unclear. We replaced all VSRs and their neighboring residues with negatively charged aspartates in a voltage-gated potassium channel. The ensuing mild functional effects indicate that hydration is also important in VSR stabilization. The voltage dependency of the VSR aspartate variants approached the expected arithmetic summation of charges at VSR positions, as if negative and positive side chains faced similar pathways. In contrast, aspartates introduced between R2 and R3 did not affect voltage dependence as if the side chains moved outside the electric field or together with it, undergoing a large displacement and volumetric remodeling. Accordingly, VSR performed osmotic work at both internal and external aqueous interfaces. Individual VSR contributions to volumetric works approached arithmetical additivity but were largely dissimilar. While R1 and R4 displaced small volumes, R2 and R3 volumetric works were massive and vectorially opposed, favoring large aqueous remodeling during VSD activation. These diverse volumetric works are, at least for R2 and R3, not compatible with VSR translocation across a unique stationary charge transfer center. Instead, VSRs may follow separated pathways across a fluctuating low-dielectric septum. © National Academy of Sciences. All rights reserved.https://www.pnas.org/content/115/32/820

Promotion to Innovation, Understanding and Transfer of Technology Through Hubs Projects Promoted by the National Secretariat of Higher Education

This article allows us to expose the promotion of innovation, entrepreneurship and technology transfer and the importance of a society demanding new things, as a result of which there is an increasingly demanding need for satisfaction for those who consume them and make the generation of new products, goods or services are mostly in demand. This research work aims to externalize the national situation of ecosystems of innovation, generation of knowledge and commercialization of the same for its use in the post of the development and consolidation of the HUB project. In this article, an exploratory research was carried out for the selection of relevant diagnostic information on these issues at the global and regional level, and a deductive study of situations already established to situations that are emerging in our country as novel fields of opportunity in difficult situations. There are disparities in the results of the HUBs at the national level, due to the difficulties that this project has generated in trying to adapt to their local realities, despite this, they have been able to generate operating regulations that support the efforts of this project and also the status regarding the activities in which each one is. Keywords: innovation, entrepreneurship, technology transfer, HUBS. Resumen Este artículo permite exponer el fomento a la innovación, el emprendimiento y la transferencia de tecnología y la importancia de una sociedad demandante de cosas nuevas, producto de ello se genera una necesidad de satisfacción cada vez más exigente de quienes las consumen y hacen que la generación de nuevos productos, bienes o servicios sean mayormente demandados. Este trabajo de investigación pretende exteriorizar la situación nacional de ecosistemas de innovación, generación de conocimiento y comercialización del mismo para su aprovechamiento en post del desarrollo y consolidación del proyecto HUB. En este artículo se realizó una investigación exploratoria para la selección de información relevante del diagnóstico de éstas temáticas a nivel mundial y regional, y un estudio deductivo de situaciones ya establecidas a situaciones que están surgiendo en nuestro país como campos novedosos de oportunidad en situaciones difíciles. Existen disparidad de resultados de los HUB´s a nivel nacional, debido a las dificultades que este proyecto ha generado al tratar de adaptarse a sus realidades locales, a pesar de ello, se han logrado generar una normativa de funcionamiento que de soporte a las gestiones de este proyecto y también el estado respecto de las actividades en las que se encuentran cada uno. Palabras clave: innovación, emprendimiento, transferencia de tecnología, HUBS

The Role of Technology in the Learning Process: A Decision Tree-Based Model Using Machine Learning

Machine learning approaches may establish a complex and non-linear relationship among input and response variables for the assessment of the Basic Education Development Index (IDEB) database and show indicators that may contribute to monitoring the quality of education. This paper uses extensive experimental databases from public schools, consisting of a case study in Brazil, to analyze data such as the physical and technological structure of schools and teacher profiles. The research proposes decision tree-based machine learning models for predictions of the best attributes to positively contribute to IDEB. It employs a newly developed SHapley Additive exPlanations (SHAP) approach to classify input variables, so to identify variables that impact the most the final model; a non-probabilistic sample was used, composed from three official databases of 450 schools, and 617 teachers. Results show that the number of computers per student, teachers’ service time, broadband internet access, investments in technology training for teachers, and computer labs in schools are the variables that have the greatest effect on IDEB. The model applied shows high prediction accuracy for test data (MSE = 0.2094 and R² = 0.8991). This article contributes to improving efficiency when monitoring parameters used to measure the quality of a teaching-learning process. Doi: 10.28991/ESJ-2022-SIED-020 Full Text: PD

On the Study of Vehicle Density in Intelligent Transportation Systems

Vehicular ad hoc networks (VANETs) are wireless communication networks which support cooperative driving among vehicles on the road. The specific characteristics of VANETs favor the development of attractive and challenging services and applications which rely on message exchanging among vehicles. These communication capabilities depend directly on the existence of nearby vehicles able to exchange information. Therefore, higher vehicle densities favor the communication among vehicles. However, vehicular communications are also strongly affected by the topology of the map (i.e., wireless signal could be attenuated due to the distance between the sender and receiver, and obstacles usually block signal transmission). In this paper, we study the influence of the roadmap topology and the number of vehicles when accounting for the vehicular communications capabilities, especially in urban scenarios. Additionally, we consider the use of two parameters: the SJ Ratio (SJR) and the Total Distance (TD), as the topology-related factors that better correlate with communications performance. Finally, we propose the use of a new density metric based on the number of vehicles, the complexity of the roadmap, and its maximum capacity. Hence, researchers will be able to accurately characterize the different urban scenarios and better validate their proposals related to cooperative Intelligent Transportation Systems based on vehicular communications

NADH Oxidation onto Different Carbon-Based Sensors: Effect of Structure and Surface-Oxygenated Groups

Different carbon-based materials have been compared for the development of NADH sensors: glassy carbon electrodes (GCE), multiwalled carbon nanotubes (MWCNT), and carbon black (CB). The GCE and MWCNT has been subjected to oxidative pretreatment to study the influence of oxidative groups for NADH oxidation. The materials had been characterized by FT-IR to identify the surface composition. The response of bare (GC) and GC/modified electrodes toward potassium ferricyanide have been employed to obtain information about the electroactive area and electron transfer rate. Studies of NAD+/NADH redox behavior showed that MWCNT and GCE exhibit high degree of passivation while CB shows no fouling effects. Catalytic effect of surface-oxygenated groups was also proved for GCE and MWCNT, and both, O-GCE and O-MWCNT, exhibited a lower oxidation overpotential compared to the respective untreated materials. Chronoamperometric quantification showed a linear dependence between 2–18 μmol·L−1 and a detection limits of 6.2 μmol·L−1 (GCE), 5.4 μmol·L−1 (O-GCE), 3.2 μmol·L−1 (GCE/CB), 9.6 μmol·L−1 (GCE/MWCNT), and 4.9 μmol·L−1 (GCE/O-MWCNT) were obtained. The analytical performances suggest that a careful choice of the material for NADH sensing is necessary depending on the sensor application