Mapas escalares de un convertidor elevador en modo corriente

"En esta contribución se analiza una clase de mapa escalar obtenido a partir de las formas de onda del convertidor elevador controlado en modo corriente pico sin rampa estabilizadora. Se establecen condiciones necesarias y suficientes para caracterizar el comportamiento estable y periódico del ciclo de trabajo. Las propiedades geométricas de los mapas escalares son ilustradas con mapas iterativos.

Copper(I)-Catalyzed Azide-Alkyne Cycloaddition Microwave-Assisted: Preparation of 7-(4-Substituted-1H1,2,3-Triazol-1-yl)-Fluoroquinolones

Nowadays, the pharmaceutical industry faces the challenge of innovating and increasing the productivity of new medicines due to the increasing multidrug resistance among bacteria, viruses and fungi. The main objective of the present study is connected quinolone and triazole molecules to enhance and broad antibacterial spectrum as well as to have multiple mechanisms of action. Preparation of 4-substituted-1H-1,2,3-triazol-1-yl in C-7 of 6-fluoro- and 6,8-difluoro-quinolone ring is showed. The synthesis involved the preparation of intermediate ethyl 7-azide-1-ethyl-fluoroquinolone-3-carboxylate, followed by copper(I)-catalyzed azide-alkyne cycloaddition to give 13 derivatives. The cycloaddition was carried out by two different methods, where it was observed that the microwave radiation was the best reaction condition, obtaining a range of yields of 47–93%, at 140 °C, 125Wmax for 10 minutes. Therefore, this methodology provided an easy pathway to synthesize a library of fluoroquinolones coupled to 1,2,3-triazole, still unexplored

Encuesta sobre Salud Reproductiva en Estudiantes Adolescentes de Educación Media Superior en Monterrey, N.L. (Mexico)

En 1999 una investigación fue llevada a cabo para obtener información sobre el conocimientoacerca de la reproducción, actividad sexual, actitudes y prácticas relacionadas con lacontracepción en jóvenes estudiantes de 15 a 19 años en Monterrey, Nuevo León, México.Participando 308 estudiantes, 61% mujeres y el 39% hombres, los cuales fueron seleccionadospara la encuesta. Se encontró que el 98.4% refieren haber recibido educación sexual, mientras que1.6% mencionan no haberla recibido, El 84.4% mencionaron haberla recibido en la escuela, un9.1%, respondieron adquirirla en el hogar, el 4.5% han recibido esta educación a través de libros yrevistas científicas y finalmente el 4.8% mencionaron haberla adquirido en la iglesia y enagrupaciones sociales. De acuerdo al rubro de vida sexual activa, los resultados muestran que 242de los encuestados que representan el 78.5%, no tienen práctica sexual. De los cuales, el 56.6%expresan que los principales motivos es por los valores transmitidos por su familia y un 20.2% porcumplir expectativas educativas y profesionales. Por otra parte se observó que 66 de ellos, el21.4% refirieron tener práctica sexual activa. Sobresaliendo que el inicio de sus relacionessexuales ocurrió a una edad de 16 y 15 años en ambos géneros con una frecuencia del 33.3% y28.7% respectivamente, una edad promedio de 17 años. De los cuales el 68.2% respondieron quesu primera experiencia la tuvieron con su novio(a), un 27.3% lo tuvo con un amigo(a) y el 4.5%refieren haberla tenido con personas desconocidas o sexo servidores. Con relación a lascondiciones asociadas a la práctica sexual activa de los 66 estudiantes se encontró, que el 43.9%mencionaron que sus experiencias no han sido con la misma persona.AbstractIn 1999 an investigation was carried out to obtain information on the knowledge about thereproduction, sexual activity, attitudes and practical related with the contraception in young studentsof 15 to 19 years in Monterrey, Nuevo León, México. Participating 308 students, 61% women andthe 39% men, which were selected for the survey. It was found that 98.4% refers to have receivedsexual education, while 1.6% mentions not to have received it, 84.4% mentioned to have received itin the school, 9.1%, they responded to acquire it in the home, 4.5% has received this educationthrough books and scientific magazines and finally 4.8% mentioned to have acquired it in thechurch and in social groupings. According to the item of active sexual life, the results show that 242of those interviewed that they represent 78.5%, they don't have sexual practice. Of those which,56.6% expresses that the main reasons are for the values transmitted by its family and 20.2% tocomplete educational expectations and professionals. On the other hand it was observed that 66 ofthem, 21.4% referred to have active sexual practice. Standing out that the beginning of its sexualrelationships happened to an age of 16 and 15 years in both goods with a frequency of 33.3% and28.7% respectively, an age 17 year-old average. Of which 68.2% responded that its first experiencehad it with its boyfriend or girlfriend, 27.3% had it with an friend and 4.5% refers to have had it withunknown people or sex servants. With relationship to the conditions associated to the active sexualpractice of the 66 students was that 43.9% mentioned that its experiences have not been with thesame person.Palabras clave: actividad sexual, jóvenes, Monterrey, México, sexual activity, youn

LA INTERRELACIÓN FAMILIAR Y LA PRÁCTICA DE RELACIONES SEXUALES EN ADOLESCENTES

Durante 1999 fue realizada una investigación para observar su interrelación familiarcon la práctica de relaciones sexuales en adolescentes de 15 a 19 años en Monterrey,Nuevo León, México. Participando 308 estudiantes, 61% mujeres y el 39% hombres,los cuales fueron seleccionados para la encuesta. De los cuales el 84.7% contesto quesus padres están casados por el civil y/o iglesia; el 84.1% estableció que sus padresconocen a sus amigos; y el 96.1% acude solo con autorización de sus padres areuniones (61.4%) o habla a casa y deja dirección y teléfono del sitio al que va(34.7%). Se observó que 66 de ellos, el 21.4% refirieron tener práctica sexual activa.Sobresaliendo que el inicio de sus relaciones sexuales ocurrió a una edad de 16 y 15años en ambos géneros con una frecuencia del 33.3% y 28.7% respectivamente, unaedad promedio de 17 años. En lo referente a la condición familiar 93 estudiantes querepresenta el 30.1% de la muestra pertenece a una familia disfuncional, y de loscuales 36.6% llevan vida sexual activa. Mientras que 215 sujetos, que constituye el69.8% se ostenta en una familia funcional y tan solo el 14.9% de ellos sobrellevanvida sexual activa. Encontrándose una asociación significativa entre pertenecer a unafamilia disfuncional y tener vida sexual activa., y aunado a que es mayor la proporciónde adolescentes con vida sexual activa pertenecientes a una familia disfuncional queen una funcional.AbstractDuring 1999 an investigation was carried out to observe its family interrelation withthe practice of sexual relationships in adolescents from 15 to 19 years in Monterrey,Nuevo León, México. Participating 308 students, 61% women and the 39% men, whichwere selected for the survey. Of which 84.7% answers that its parents are married bythe civil and/or church; 84.1% established that its parents know their friends; and96.1% goes alone with authorization of its parents to meetings (61.4%) or he/shespeaks to house and he/she leaves address and telephone from the place to whichgoes (34.7%). it was observed that 66 of them, 21.4% referred to have active sexualpractice. Standing out that the beginning of its sexual relationships happened to anage of 16 and 15 years in both goods with a frequency of 33.3% and 28.7%respectively, an age 17 year-old average. Regarding the condition family 93 studentsthat represents 30.1% of the sample it belongs to a family no-functional, and of which36.6% takes active sexual life. While 215 fellows that it constitutes 69.8% are shownin a functional and so alone family 14.9% of them has active sexual life. Being asignificant association between to belong to a family no-functional and to have activesexual life., and joined to that is bigger the proportion of adolescents with activesexual life belonging to a family no-functional that in a functional one.Palabras clave: Familia disfuncional, actividad sexual, jóvenes, Monterrey, México, Family no-functional, sexual activity, young

Confined Pt11+ Water Clusters in a MOF Catalyze the Low‐Temperature Water–Gas Shift Reaction with both CO2 Oxygen Atoms Coming from Water

The synthesis and reactivity of single metal atoms in a low‐valence state bound to just water, rather than to organic ligands or surfaces, is a major experimental challenge. Herein, we show a gram‐scale wet synthesis of Pt11+ stabilized in a confined space by a crystallographically well‐defined first water sphere, and with a second coordination sphere linked to a metal–organic framework (MOF) through electrostatic and H‐bonding interactions. The role of the water cluster is not only isolating and stabilizing the Pt atoms, but also regulating the charge of the metal and the adsorption of reactants. This is shown for the low‐temperature water–gas shift reaction (WGSR: CO + H2O → CO2 + H2), where both metal coordinated and H‐bonded water molecules trigger a double water attack mechanism to CO and give CO2 with both oxygen atoms coming from water. The stabilized Pt1+ single sites allow performing the WGSR at temperatures as low as 50 °C.This work was supported by the MINECO (Spain) (Projects CTQ2016–75671–P, MAT2013 40823–R, MAT2016–81732–ERC, CTQ2017–86735–P, MAT2017–86992–R, MAT2017–82288–C2–1–P and Excellence Units “Severo Ochoa” and “Maria de Maeztu” SEV–2016–0683 and MDM–2015–0538) the Generalitat Valenciana (PROMETEOII/2014/004) and the Ministero dell’Istruzione, dell’Università e della Ricerca (Italy) and the Junta de Andalucía (FQM–195). M. M. and M.–A. R. C. thanks the MINECO for a predoctoral contract. Thanks are also extended to the Ramón y Cajal Program (E. V. R.–F., E. P. and J.–C. H.–G.) and the “Subprograma atracció de talent–contractes postdoctorals de la Universitat de Valencia” (J. F.–S.). M. L.–H. acknowledges the financial support from the Juan de la Cierva Fellowships Program of MINECO (IJCI–2014–19367)

Repetitive controller for compensation of periodic signal

"A repetitive controller scheme with positive feedback and feedforward introduces infinitely many poles on the imaginary axis located at the resonant peaks. The feedforward introduces zeros, which produce notches located in between two consecutive resonant peaks. The latter has the advantage of making the controller more selective, in the sense that; the original overlapping (appearing at the valleys in a simple positive feedback repetitive controller) or interaction between consecutive resonant peaks is removed by the notches. This would allow, in principle, peaks of higher gains and slightly wider bandwidth, avoiding, at the same time, the excitation of harmonics located in between two consecutive peaks. The repetitive controller includes a simple Low Pass Filter (LPF).; This modification restricts the bandwidth of the controller and at the same time reinforces stability when the controller is inserted in the closed-loop system.

Repetitive controller to compensate for odd harmonics

"A repetitive controller scheme with negative feedback and feedforward introduces infinitely many poles on the imaginary axis located at the resonant peaks. The feedforward introduces zeros, which produce notches located in between two consecutive resonant peaks. The latter has the advantage of making the controllers more selective, in the sense that the original overlapping (appearing at the valleys) or interaction between consecutive resonant peaks is removed by the notches. This would allow, in principle, peaks of higher gains and slightly wider bandwidth, avoiding, at the same time, the excitation of harmonics located in between two consecutive peaks. A negative feedback compensator with feedforward is especially useful when only the compensation of odd harmonics is required, but not the even harmonics, like in many power electronic systems.; In contrast, the positive feedback controller would try to reinject, and indeed amplify, any small noise, which has components on the even frequencies. The negative feedback repetitive controller includes a simple Low Pass Filter (LPF). This modification restricts the bandwidth of the controller, and at the same time reinforces the stability when the controller is inserted in a closed-loop system.

Convertidor elevador: mapa unidimensional y dinámica no lineal

"En esta contribución se realiza el desarrollo de un mapa discreto en el tiempo del convertidor elevador controlado en modo corriente pico a partir de sus formas de onda. Se presentan criterios de existencia de puntos fijos, puntos periódicos y su estabilidad. Las propiedades geométricas del mapa discreto son ilustradas mediante ejemplos de simulación.

Impacto de las TIC en la práctica docente a nivel superior durante el covid-19

COVID-19 has been one of the biggest global impacts with significant influence on the education sector. Due to the health contingency, it forced a rethinking of teaching methods and a shift to virtual modalities, which demanded the development of new skills from the educational community, particularly the use and integration of Information and Communication Technologies (ICT) as the primary means of interaction between students and teachers. Therefore, the objective of this article was to analyze the impact of ICT integration on the teaching practices of faculty members in the Academic Division of Education and Arts (DAEA) at the Autonomous University of Tabasco (UJAT). This study was conducted using a quantitative paradigm, under an empirical analytical approach of ex post-facto research. The results indicate that the faculty members made good use of and integration with ICT, with 16.0% of the teachers possessing digital competencies. However, 8.0% expressed disagreement. In conclusion, it is essential to consider the needs of educators in order to improve their digital skills and promote innovation in the teaching and learning process.El COVID-19 ha sido uno de los impactos más grandes a nivel mundial con mayor influencia en el sector educativo, a causa de la contingencia sanitaria esta orilló a repensar la enseñanza, a cambiar a una modalidad virtual que exigió a la comunidad educativa el desarrollo de nuevas habilidades, en especial el uso e integración de las tecnologías de la información y comunicación (TIC) como principal fuente de interacción entre alumno y profesor. Por tal motivo, el objetivo del presente artículo fue analizar el impacto de la integración de las TIC en la práctica de los docentes en la División académica de Educación y Artes (DAEA) de la Universidad Juárez Autónoma de Tabasco (UJAT). Este estudio se realizó a partir del paradigma cuantitativo, bajo el enfoque empírico analítico de tipo de investigación ex post-facto. Los resultados indican que los docentes hicieron buen uso e integración de las TIC, asimismo el 16.0% de los docentes contaban con las competencias digitales. Sin embargo, el 8.0% indicó estar en desacuerdo. En conclusión, es fundamental tener en cuenta las necesidades de los educadores con el fin de mejorar sus habilidades digitales y fomentar la innovación en el proceso de enseñanza-aprendizaje