Benemérita Universidad Autónoma de Puebla
Recent publications
Surface modification has been widely employed to modify fundamental properties of two-dimensional (2D) materials and create new multifunctional candidates for practical applications. In this work, the effects of chemical functionalization on silicon germanide (SiGe) monolayer have been investigated using first-principles calculations. Pristine monolayer exhibits good dynamical stability and a Dirac cone at point in the band structure. The nearly semimetallic nature and absence of magnetic properties represent great challenge for SiGe monolayer applications. Our results show that these deficiencies can be overcome with oxygenation and hydrogenation processes. Oxygen (O) and hydrogen (H) atoms prefer to be adsorbed on-top of bridge and Si atom, respectively. The non magnetic nature is preserved under oxygenation, however a significant band gap up to 1.35 eV can be introduced depending on the O concentration. Meanwhile, the ferromagnetic semiconducting is induced by hydrogenation, where magnetic properties are produced mainly by Ge atoms, regardless the H coverage. In fact, efficient methods have been introduced to make SiGe monolayer promising 2D material for optoelectronic and spintronic applications through adsorbing O and H atoms.
Optical cavitation can be induced by short pulse lasers focused into a solution with a low absorption coefficient or using a continuous-wave laser focused into highly absorbent solutions. In this work, we report the generation of cavitation bubbles in ethanol using a continuous-wave fiber optic laser with emission at 450 nm wavelength. Silver and copper nitrate nanoparticles were immobilized on the flat end-face of a multimode optical fiber tip using the photodeposition technique and then immersed into the solution. Laser light transmitted through the optical fiber is strongly absorbed by both nanoparticles causing an abrupt increase in temperature around the tip of the optical fiber, reaching the spinodal limit of ethanol (∼187 °C). At this temperature, an explosive phase transition (liquid–gas) occurs causing the generation of a microbubble, which grows until reaches its maximum radius (∼1072 μm in 132 µs) and subsequently collapses, emitting a shock wave. The dynamic behavior of the gas bubble was studied as a function of the laser power using a high-speed video camera, and the shock wave emitted immediately after the bubblés collapse was detected by a microphone. The pressure of the shock wave was analyzed photodepositing different thin films of silver nanoparticles at the tip of the optical fiber, causing optical attenuations of 1, 3, 5, and 7 dB. The experimental results obtained showed that when a thin film of copper nitrate nanoparticles was photodeposited on a film of silver nanoparticles (5 dB), the pressure of the shock wave increases up to ∼ 13-fold, in comparison, if we use only one film of silver nanoparticles. Energetic shock waves have potential applications in a variety of areas such as medicine, biological sciences, material processing, liquid microjets generation, among others.
On the basis of first-principles projector augmented wave method, the effects of point defects and doping on the MgO monolayer electronic and magnetic properties are studied. Pristine monolayer is an insulator two-dimensional (2D) material with a band gap of 3.37 eV. Various defect types including single vacancy of Mg (VMg) and O (VO), Mg+O divacancy (VMgO), and antisites formed by replacing one Mg atom by one O atom (OMg), one O atom by one Mg atom (MgO) and exchanging position of one Mg-O pair (Mg↔O) have been considered. Material becomes ferromagnetic semiconductor upon creating a Mg single vacancy, whose magnetic properties are produced mainly by O atoms closest to the defect site. Meanwhile, the non-magnetic nature is preserved in other cases with a significant variation of the electronic band gap. Similarly, non-magnetic features are obtained when substituting one Mg atom by one Si or Ge atom (SiMg and GeMg). In contrast, the feature-rich half-metallicity (semiconductor spin-up state and metallic spin-down state) is induced when doping at O site (SiO and GeO). In these cases, magnetism is generated mainly by dopants with a small contribution from their neighbor O atoms. This work provides important insights on the MgO monolayer purposing efficient approaches to widen its working region for optoelectronic applications, as well as make it prospective to be applied as spin-filter and generate spin current in spintronic devices.
Although individuals with schizophrenia typically present deficits in social interaction, little is known about the quality of their parent–infant interactions. In the present study, we assessed the behavioral effects of neonatal ventral hippocampus lesion (nVHL) in female rats (nVHL is known to induce schizophrenia‐like deficits in males). Sexually naïve adult nVHL or sham female rats received cognitive and social tests, and their maternal behavior was observed in independent groups of adult nVHL and sham rats on postpartum days 2, 6, and 12. Compared to Sham females, naïve nVHL rats displayed elevated locomotor activity, less social interaction, and disrupted habituation of the acoustic startle response (ASR), while dorsal immobility (a defensive behavioral response) and prepulse inhibition of ASR were not affected. Although all nVHL mothers retrieved their pups, adopted the crouching posture, and nursed them, they showed disturbances in the display of pup body licking and nest building. Furthermore, a high proportion of nVHL mothers displayed atypical retrieval of pups and re‐retrieving of pups, atypical nest‐building, excavation, and cannibalism, as well a high level of these behaviors. These data indicate that cognition, locomotor activity, and maternal care is disrupted in nVHL female, suggesting disturbances in mesocorticolimbic dopaminergic systems and/or in social cognition.
For the Mexican Otomi of the Sierra Norte de Puebla, Santa Rosa is a sacred plant used by the shaman to heal people and sing in rituals called costumbres. It is also an Antigua, a sacred deity who maintains a constant dialogue with ritual specialists. In the Otomi discourse and its worldview of Santa Rosa, as well as in its ritual process, it is eaten, not smoked. Although it is cannabis, they mention that: "the Santa Rosa is eaten, it is sacred; marijuana, the one they smoke in Mexico, is another one that looks like it."
Due to its chemical properties, glyphosate [N-(phosphonomethyl)glycine] is one of the most commonly used agricultural herbicides globally. Due to risks associated with human exposure to glyphosate and its potential harmfulness, the need to develop specific, accurate, online, and sensitive methods is imperative. In accordance with this, the present review is focused on recent advances in developing nanomaterial-based sensors for glyphosate detection. Reported data from the literature concerning glyphosate detection in the different matrices using analytical methods (mostly chromatographic techniques) are presented; however, they are expensive and time-consuming. In this sense, nanosensors’ potential applications are explained to establish their advantages over traditional glyphosate detection methods. Zero-dimensional (0D), one-dimensional (1D), two-dimensional (2D), and three- dimensional (3D) materials are reviewed, from biomolecules to metallic compounds. Bionanomaterials have generated research interest due to their selectivity with respect to using enzymes, DNA, or antibodies. On the other hand, Quantum Dots also are becoming relevant for their vast surface area and good limit of detection values (in the range of pM). This review presents all the characteristics and potential applications of different nanomaterials for sensor development, bearing in mind the necessity of a glyphosate detection method with high sensitivity, selectivity, and portability.
The interaction of α-glucose with a BN-nanosheet, BN-nanotube, and BN-fullerene, was analyzed from an atomistic and electronic point of view, to evaluate such nanostructures as possible carriers and/or biosensors of the α-glucose molecule. Adsorption energies are in the range of physisorption (-0.79 eV to -0.91 eV) for the BN-nanosheet and -nanotube, and chemisorption (-2.24 eV to -2.35 eV), for the BN-fullerene. All systems, exhibit semiconductor-like behavior and great stability according to |LUMO-HOMO| energy gap [GapLH] and chemical potential values, respectively. For the BN-nanosheet and -nanotube, the stabilization of the complexes is through hydrogen bonds, while for BN-fullerene is through a covalent bond and charge transfer. Furthermore, the BN-fullerene is able to dissociate the α-glucose molecule, which could help to decomposer such a compound, and be used for biological applications. The data taking into consideration solvent effects have no significant impact with respect to gas phase, except in the dipole moment (Md) where we noticed an increase up to ~ 45 %. Our results suggest that BN-nanosheet and -nanotube, may act as biosensors, while BN-fullerene, may serve as a carrier or degrader of the α-glucose molecule.
El recorrido formativo de los doctorandos para la realización de sus investigaciones se acompaña de procesos de lectura académica complejos, sin embargo, existen escasas investigaciones que lleven a cabo un análisis al respecto, así como en lo referente a la función pedagógica que puede desempeñar el director de tesis para favorecer el desarrollo de este tipo de lectura. Dada esta situación, en el presente ensayo, a partir de un análisis de estudios que se enfocan o se aproximan a esta temática, se visibilizan los desafíos que requieren afrontar los doctorandos al efectuar distintos tipos de lectura acorde con los diferentes procesos de su investigación. Así también se abordan recursos pedagógicos que pueden aplicar los directores de tesis para coadyuvar al desarrollo de una lectura académica enfocada a la investigación, en los que se considere el proceso formativo del doctorando. Aunado a ello se señala la necesidad de realizar estudios que permitan una comprensión mayor de los procesos de lectura académica de los doctorandos, así como el desarrollo de estrategias pedagógicas sistematizadas que pueda aplicar el director de tesis para favorecerlos, acorde con el proceso formativo del estudiante y su campo disciplinar.
Climate change and COVID‐19 pandemic represent two of the biggest problems that our society is facing currently. One of the key aspects in the strategy of solutions for those problems is the detection and monitoring of CO2. Doped‐metal oxide semiconductors are a promising technology for gas sensor applications due to remarkable properties in comparison with other developments. In this work, ZnO, Ni and Al doped ZnO nanoparticles were synthesized via ultrasound assisted sol‐gel technique. XRD analysis revealed a correlation between structural parameters (lattice parameters, crystallite size, dislocation density and micro‐strain) and the dopant ions incorporation. SEM studies showed changes in morphology in doped samples derived from the effect of restriction on the growth dynamics. A growth mechanism was proposed in order to explain the properties of ZnO‐based sensors. Gas sensing tests were carried out, delivering the best results as follows: an 89% sensing response at 500 ppm of CO2, 0.54 MΩ/s of sensitivity, 52/48 s for average response and recovery times respectively, in the Ni‐doped ZnO sample. Additionally, selectivity evaluations for all samples were also performed. By comparing the obtained structural and morphological characteristics with the gas sensing properties of the samples, Ni doped ZnO samples have optimal characteristics for CO2 detection due to the high surface area and abundant oxygen vacancies resulting from the Ni incorporation. Gas sensing mechanism of each sample was reported and discussed in this work. This article is protected by copyright. All rights reserved.
In this work, we present a numerical algorithm to solve the inverse problem of volumetric sources from measurements on the boundary of a non-homogeneous conductive medium, which is made of conductive layers with constant conductivity in each layer. This inverse problem is ill-posed since there is more than one source that can generate the same measurement. Furthermore, the ill-posedness is due to the fact that small variations (or errors) in the measurement (input data) can produce substantial variations in the identified source location. We propose two steps to solve this inverse problem in some classes of sources: we first recover the harmonic part of the volumetric source, and, in a second step, we compute the non-harmonic part of the source. For the reconstruction of the harmonic part of the source, we follow a variational approach based on the reformulation of the inverse problem as a distributed control problem, for which the cost function incorporates a penalized term with the input data on the boundary. This cost function is minimized by a conjugate gradient algorithm in combination with a finite element discretization. We recover the non-harmonic component of the source using a priori information and an iterative algorithm for some particular classes of sources. To validate the numerical methodology, we develop synthetic examples both in circular (simple) and irregular (complex) regions. The numerical results show that the proposed methodology allows to recover the complete source and produce stable and accurate numerical solutions.
The aim of the present study was to synthesize isoflavone-enaminones 3a-c and 7-alkoxy-isoflavones 4a-c, evaluate their inhibition of α-glucosidase, and analyze the bioisosteric effect of the presence versus absence of aromatic moieties in these benzopyran derivatives. All the test compounds exhibited greater inhibition of α-glucosidase than the positive control acarbose. The series of isoflavones 3a-c and 4a-c showed higher inhibitory activity (IC50 = 6.3–87.6 µM) than the parental 7-hydroxyisoflavones 2a-c (IC50 = 109.4–173.2 µM), suggesting that the attachment of a 4’-chloroacetophenone moiety to the 7-hydroxyl group of 2a-c is an efficient way to increase the inhibition of α-glucosidase. Furthermore, the aromatic moieties of the series of compounds 3 and 4 enhance inhibitory activity by hydrophobic effects, according to docking calculations. Graphical abstract
Air pollution reduction is key for the human health and the environment, particularly, the elimination of NO2 gas is important since it generates severe respiratory diseases. We performed a systematic theoretical study to investigate the NO2 trapping on graphene functionalized with some transition metal atoms. Cr, Cu, Pt, Ti and Zn are treated. To further understand the interaction between NO2 molecule and doped graphene, the partial density of states (PDOS) was calculated for each system, considering spin polarization. PDOS shows that Cr-, Cu- and Zn-doping induces magnetism in the graphene layer by breaking the spin-up and spin-down symmetries. Moreover, after the NO2 molecule adsorption on Cr- and Zn-doped systems, graphene preserves the magnetic behavior. When two transition metals were considered, Pt and Ti, doping graphene with (2Pt or 2Ti) or co-doping it with (Pt and Ti). Our results suggest that 2Ti doped graphene is the most promising for NO2 removal.
The title metal–organic polymer, catena -poly[[(5,5′-dimethyl-2,2′-bipyridine-κ ² N , N ′)iron(II)]-di-μ-azido-κ ² N ¹ : N ³ -[(5,5′-dimethyl-2,2′-bipyridine-κ ² N , N ′)iron(II)]-di-μ-azido-κ ² N ¹ : N ¹ ], [Fe(N 3 ) 2 (C 12 H 12 N 2 )] n , features alternating μ-1,1 ( end-on mode of coordination) and μ-1,3 ( end-to-end mode of coordination) double azide bridges, forming chains running in the [100] direction. The octahedral coordination geometry around the Fe II centre is completed by a bidentate 5,5′-dimethyl-2,2′-bipyridine ligand. Two polymorphs for this compound were obtained from the crude reaction product, the first in the space group P \overline{1} and the other in P 2 1 / c . The molecular and crystal structures are very similar for both forms, the main difference being that the eight-membered Fe(μ-1,3-N 3 ) 2 Fe metallacycle formed with end-to-end azide ligands has a nearly flat conformation in the triclinic form and a chair conformation in the monoclinic form. In spite of this geometric difference, both forms have the same density, the same packing index and similar arrangements of the one-dimensional chains in the crystal. As a consequence, they also share very similar Hirshfeld surfaces and fingerprint plots. However, a density functional theory (DFT) computational study showed that the monoclinic form is more stable than the triclinic form by ca 30.5 kJ mol ⁻¹ .
A pesar de los grandes esfuerzos en tiempo y dedicación para lograr los aprendizajes esperados del currículo escolar, los números racionales siguen siendo un tema de alta complejidad para los estudiantes de bachillerato porque apenas si llegan a la comprensión de los conceptos más básicos y elementales. A partir de la Teoría de Registros de Representación Semiótica (TRRS) de Raymond Duval y de la Teoría de las Inteligencias Múltiples (IM) de Howard Gardner, se diseñaron e implementaron tres estrategias de enseñanza basadas en distintas representaciones semióticas, favoreciendo el desarrollo de la inteligencia espacial con los planteamientos de la Ingeniería Didáctica para favorecer el aprendizaje de los números racionales en estudiantes de primer año de bachillerato. Además, se diseñó y aplicó una misma actividad que sirvió como pretest y postest para comparar resultados y podernos dar cuenta si la estrategia didáctica ayudó a la adquisición del concepto de número racional. A partir de los resultados obtenidos, pudimos concluir que las actividades sirvieron para incrementar el aprendizaje del concepto de número racional.
La innovación y el desarrollo tecnológico son factores clave en el siglo XXI, la Cuarta Revolución Industrial se visualiza como un eje transversal en las distintas áreas de la sociedad. En este tema se rescata el concepto de tecnoeconomía (Heginbotham & Samuels, 1998) en la región del noreste asiático. El objetivo de esta investigación consiste en determinar el grado de adaptación de una tecno-economía a la nueva normalidad económica del modelo de desarrollo tetrahélice. Los resultados de esta investigación van dirigidos a enfatizar la directriz estatal y el lobbying empresarial en las tecnoeconomías.
We describe and identify fossil material of turtles recovered from several Pleistocene localities of Hidalgo and Puebla. A comparative study with selected specimens of extant and extinct turtles revealed that the fossil sample evidences two families (Kinosternidae and Testudinidae), three genera (Kinosternon, Gopherus, and aff. Hesperotestudo), and two species (K. flavescens and G. berlandieri). This record supplements their occurrence in the country, being common inhabitants of central Mexico. We performed a paleoclimatic reconstruction of the Valsequillo Basin using the Mutual Ecogeographic Range (MER) method, given that in this area the fossil material was identified to species level, including K. flavescens and G. berlandieri. The potential climatic conditions based on the distribution model and the current habitats of these turtles suggest that the climate was warmer with similar precipitation (21.99 °C mean annual temperature and 623 mm mean annual precipitation) in comparison to the current ones (17 °C mean annual temperature and 622.2 mm mean annual precipitation). By the same token, the presence of xerophytic thickets and desert areas suitable for G. berlandieri, associated with bodies of water inhabited by K. flavescens, is proposed.
The synthesis of new 1,2 disubstituted ferrocenylated unsymmetrical potentially tridentate selenoether and telluroether ligands, containing Oxygen and Nitrogen at the other donor sites and their respective palladium complexes were synthesized. These compounds were characterized by elemental analyses, (¹H, ¹³C, ⁷⁷Se, or ¹²⁵Te) NMR, variable temperature NMR studies and IR, UV-vis spectroscopy, mass spectrometry, and cyclic voltammetry. The molecular structures of all the palladium complexes were determined by X-ray crystallography which confirms that these ligands coordinate in a bidentate fashion. The structures of the two complexes show IChB, E···O interactions while the packing of all these complexes presents E···E, C-H···Cl, and E···Cl interactions (E= Se or Te). Interestingly chalcogenoether ligands containing the 3-hydroxy propyl group and their palladium complexes are soluble in water and ¹H-NMR spectra of these ligands do not show O-H proton signal at room temperature but at low temperature broad deshielded proton signal confirms the involvement of -OH group in secondary interactions with Se or Te atom as an intramolecular chalcogen bonding (IChB). The concomitant cleavage of the C-E bond has been reported and a new cyclopalladated complex was isolated and its X-ray crystal structure was determined. In UV-vis spectroscopy of all the compounds, the characteristic absorption bands of ferrocenyl motif, n→σ* transition, and ligand to metal charge transfer (LMCT) transition have been observed. Furthermore, the cyclic voltammograms of selenoether and their complexes present single reversible and quasi reversible waves while telluroether ligands present three quasi reversible processes and their complexes show three nonreversible redox processes.
We present a model of shear wave velocity for the botanical garden of the Benemérita Universidad Autónoma de Puebla in Puebla City using ambient seismic noise recorded on a geotechnical scale array. We estimate phase velocity dispersion curves of Rayleigh waves, using the Modified Spatial Autocorrelation Method (MSPAC), between 1.5 and 7.1 Hz. Also, in each station the Horizontal-Vertical Spectral Ratio was calculated (HVSR). To obtain shear wave velocity profiles, congruent with the fundamental period of the site, we carry out a joint inversion between the HVSR and the phase velocity dispersion curves under the assumption that ambient seismic noise is a diffuse field. To improve the resolution of the velocity models, we recovered the Green's function by time domain cross-correlation of ambient seismic noise in a range of 5.3–12 Hz and calculated the travel times of the wave trains between pairs of stations. Then, with depth inversions, the velocity profile at the first 25 m was estimated. Finally, the assembly of our results give rise to the improved model. The shear wave velocity model comprises five layers over a half-space reaching exploration depths of up to 215 m, according to the sensitive kernels. The resolution obtained, the depth of investigation achieved and the congruence of the models with the fundamental period of the site, make these 1D models ideal for estimating the site response to ground motions caused by seismic events.
We present the set and setting of the velada, the Mazatec ritual of divination and healing. We highlight the subjective experiences of individuals who consumed sacred mushrooms and interpret them from their cultural and community contexts, but also from findings derived from experimental and neuroscientific research. We understand that the experiences connected to sacred mushrooms can be explained by the effects of psilocybin on the neurobiology of emotions, decision making, and visual, auditory, and bodily imagery. But we also understand that experimentation does not consider the individual and collective history of the person, and that the velada can provide guidance for integrating a person’s history and beliefs into experimental designs. The resurgence of psychedelic medicine prompts us into a transdisciplinary dialogue that encompasses both the anthropological perspective and the set and setting of the entheogenic experience during the sacred mushroom ritual.
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8,295 members
Guillermo De Ita
  • Facultad de Ciencias de la Computación
ROBERTO C. Ambrosio
  • Facultad de Ciencias de la Electrónica
C.E. Ochoa Velasco
  • Facultad de Ciencias Químicas
Alvaro Sampieri
  • Facultad de Ingeniería Química
Alejandro Carabarin-Lima
  • Instituto de Ciencias ICUAP
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Av. 14 sur 6301, col. San Manuel, 72570, Puebla, Puebla, Mexico
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www.buap.mx
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