DFT analysis of the adsorption of bisphenol A (BPA) on pristine and oxidized phosphorene.

CONTEXT: Bisphenol A is an endocrine disruptor that may cause harmful effects on human health. Some residues of this compound have been found in water bodies, alerting for its possible risk as an environmental pollutant. Thus, this work proposes the use of pristine and oxidized phosphorene as removers of bisphenol A, through an adsorption mechanism. Our results indicate that the main interactions exhibited by the complexes are hydrogen bonds, van der Waals, and n-π stacking. All complexes show adsorption energies less than -1.08 eV for the gas phase, and -0.65 eV for the aqueous environment, suggesting that the models may be good capturers of this pollutant. According to the electronic properties, the systems are good donators/acceptors of charge; likewise, they are suitable to sense bisphenol A, because of their changes in |LUMO-HOMO| gap energy. The values obtained suggest that the number of oxygen atoms in the models is important for their adsorption capabilities; hence, the modulation in the oxidation is significant to enhance such properties. METHODOLOGY: Density functional theory calculations were implemented at the PBE-D3/TZVP level of theory in the ORCA 5.0 program, to evaluate the adsorption of bisphenol A on pristine and oxidized phosphorene models and propose the last as removers of this molecule. The visualization of the structures was done in the VMD code.

Binary adsorption isotherms of methylene blue and crystal violet on mandarin peels: prediction via detailed multivariate calibration and density functional theory (DFT) calculations.

The multicomponent adsorption of synthetic dyes has great relevance in the treatment of effluents due to the complexity of the adsorbate-adsorbent interactions. Therefore, this study provides useful information about the adsorption capacity of methylene blue (MB) and crystal violet (CV) in a bioadsorbent (mandarin peels) in a single-component and competitive system using detailed multivariate calibration analysis. The PLS1 multivariate calibration model was used to quantify the adsorbates. In mono and two-component systems, the adsorption capacity of CV (1.26-1.36 mg g-1) was superior when compared to MB (0.925-0.913 mg g-1), characterizing synergistic adsorption for CV and antagonistic adsorption for MB. The Sips model was effective for describing single-component systems, suggesting that adsorption did not occur in the monolayer. For competitive adsorption, modified, unmodified, and extended models were used to understand the interactions between the dyes and the bioadsorbent. The modified Redlich-Peterson (MRP) model was effective in describing the behavior of the binary system, indicating that the interaction forces with the adsorbate were significant. Thus, the bioadsorbent showed promising results for competitive adsorption, thus being of relevance to the industrial sector. Density functional calculations were also performed to characterize the atomic interactions for the removal of both dyes on mandarin peels.

Insights on α-Glucose Biosensors/Carriers Based on Boron-Nitride Nanomaterials from an Atomistic and Electronic Point of View.

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.

The antioxidant capacity of an imidazole alkaloids family through single-electron transfer reactions.

The single-electron transfer (SET) reactions from the neutral and mono-anion species of five imidazole alkaloids (lepidines A, B, C, D, and E) against hydroperoxyl radicals have been studied using the density functional theory and the Marcus theory. The deprotonated species of three alkaloids were found to have free radical scavenging activity. The antioxidant activity was studied via single-electron transfer (SET) under physiological conditions. The SET reactions for lepidines B, D, and E were found to have rate constants ranging from 105 to 106 M-1 s-1. Therefore, they are predicted to be able to deactivate hydroperoxyl radicals and therefore the damage caused by them to polyunsaturated fatty acids. It is important to mention that the acid-base equilibrium plays an important role in their free radical scavenging activity. Graphical abstract Lepidines are predicted to be able to deactivate hydroperoxyl radicals and the damage caused by them to polyunsaturated fatty acids.

[The social determinants of child malnutrition in Colombia from a family medicine perspective]. / Los determinantes sociales de la desnutrición infantil en Colombia vistos desde la medicina familiar.

CONTEXT: Child malnutrition is a public health problem not only in Colombia but throughout the world, as it increases mortality associated with preventable causes. In Colombia, poverty is one of those causes present mainly in rural areas where one in 10 children suffers from malnutrition. METHODOLOGY: We searched ScienceDirect, PubMed, ClinicalKey, and SciELO for references on child malnutrition, its social determinants, and elements for its intervention in Colombia. RESULTS: The review allowed us to identify that many factors influence this problem determined not only by the lack of food but also by other factors such as poverty, lack of resources, restricted access to health care, rising prices of essential foods, political conflicts leading forced displacement, drought, the absence of an equity-based policy approach, poor environmental sanitation, among others. CONCLUSIONS: Child malnutrition should not be conceived as mainly a food-related problem. Other factors that influence this problem should also be taken into account in order to prevent it. Trained personnel should be deployed to intervene in the social determinants that underpin child malnutrition. Thus, in Colombia, the family physician is a fundamental link in the health system, responsible for providing comprehensive medical care and for the leadership of the newly introduced health model based on primary health care.

CONTEXTO: La desnutrición infantil es un problema de salud pública no solo en Colombia, sino en todo el mundo, ya que aumenta la mortalidad asociada a causas que son prevenibles. En Colombia, la pobreza es una de esas causas, la cual se presenta principalmente en las zonas rurales, en donde uno de cada 10 niños presenta desnutrición. METODOLOGÍA: Se realizó una revisión a partir de la búsqueda de artículos en bases de datos electrónicas (ScienceDirect, PubMed, ClinicalKey y SciELO) y en referentes normativos sobre la desnutrición infantil, sus determinantes sociales y elementos para su intervención en Colombia. RESULTADOS: La revisión permitió identificar que son muchos los factores que influyen en esta condición que está determinada no solo por la falta de alimentos sino también por causas como la pobreza, la falta de recursos, una atención insuficiente, el alza en el precio de los alimentos básicos, los conflictos que originan desplazamientos masivos de la población, la sequía, la ausencia de un enfoque de equidad y el mal saneamiento ambiental, entre otros. CONCLUSIONES: Es importante dejar de concebir la desnutrición infantil como un problema exclusivamente alimentario. También es necesario tener en cuenta que en ella influyen otros factores que se deben trabajar para evitar esta enfermedad, los cuales deben ser intervenidos por personal capacitado para generar impacto en los determinantes sociales causantes de esta problemática. De ese modo en Colombia, el médico familiar se constituye como un eslabón fundamental del sistema de salud, el cual tiene como función de proveer atención médica integral y de liderar el nuevo modelo de salud basado en la atención primaria en salud.

Functionalized graphene pieces to trap the insecticide imidacloprid: a theoretical analysis.

Eleven adducts for the interaction between imidacloprid (IMI) and some activated carbon (AC) pieces are proposed in this work. Activated carbon pieces were obtained by using a finite zig-zag graphene structure saturated with hydrogen atoms on the edges giving a pristine model with 70 carbon atoms and 22 hydrogen atoms. The zig-zag graphene structure was oxidized with -O, -COOH, -OH, and -O- groups. In this process, two identical groups were inserted over selected sites of the pristine model. All of these structures yielded ten IMI-AC adducts by using the PBE0-D3/6-31G* method, which predicts stable adducts at 0 K, and six of our models give negative free energies changes at room temperature. Thus, we expect that our IMI-AC models can be present when IMI interacts with an AC model. For one of the IMI-AC adducts, we applied solid-state techniques to avoid border effects, and we found that the imidacloprid is deprotonated giving reactive species, suggesting a new path to degrade this insecticide. Additionally, from this analysis, we proposed an additional IMI-AC adduct, which involves high free energy at room temperature. With this study, we show that our AC models can trap imidacloprid, which is quite convenient to remove this insecticide from our environment. Although it is well recognized that functionalized graphene structures are designed to trap some chemical compounds, to the best of our knowledge, this is the first time where IMI-graphene pieces interactions are studied in detail, and hydrogen bonds are analyzed through some scalar fields defined in quantum chemistry like the electron density and the non-covalent interactions index.

Duplicación Uretral: Reporte de Caso / Urethral Duplication: Case Report

Preescolar, Masculino, 3 años 9 meses con antecedente quirúrgico de corrección de hipospadias 1er tiempo hace 2 años y que durante el 2do tiempo de corrección de hipospadias se encuentra incidentalmente una duplicación uretral tipo IB. Se confirma por medio de instilación de azul de metileno por uretra ventral y luego por medio de uretrocistoscopia. Se realiza la resección y cierre de uretra dorsal. Requiere de una dilatación uretral y está pendiente la corrección quirúrgica de una fistula uretrocútanea.

We report the case of a 3 year 9 month old boy who had a failed hypospadia correction two years prior to his second surgery when a IB urethral duplication was incidentally found. There are only 300 case reports of this published. The diagnosis was confirmed by instilling methylene blue through the ventral urethra, by urethero-cystoscopy. Resection and closure of the dorsourethra was performed. He required a urethral dilatation and developed aurethero-cutaneous fistula, which is pending surgical correction.

Numerical absorbing boundary conditions based on a damped wave equation for pseudospectral time-domain acoustic simulations.

In the context of wave-like phenomena, Fourier pseudospectral time-domain (PSTD) algorithms are some of the most efficient time-domain numerical methods for engineering applications. One important drawback of these methods is the so-called Gibbs phenomenon. This error can be avoided by using absorbing boundary conditions (ABC) at the end of the simulations. However, there is an important lack of ABC using a PSTD methods on a wave equation. In this paper, we present an ABC model based on a PSTD damped wave equation with an absorption parameter that depends on the position. Some examples of optimum variation profiles are studied analytically and numerically. Finally, the results of this model are also compared to another ABC model based on an hybrid formulation of the scalar perfectly matched layer.

Manejo quirúrgico de la obstrucción intestinal neonatal / Surgical management of neonatal intestinal obstruction

La Obstrucción Intestinal Meonatal es una emergecia quirúrgica de la que depende la sobrevivencia del neonato. Gracias a los adelantos tecnológicos existe una sobrevida del 95/100 En este estudio se revisaron los expedientes clínicos de los neonatos con diagnóstico de Obstrucción Intestinal de 1987a 1992, encontrando un total de 46 casos de los cuales 67.4/100 casos correspondieron a Atresia Intestinal. Mal Rotación Intestinal en 13/100 , Bandas Congénitas en 10.9/100 Pancreas anular en 4.35/100 Enfermedad de Hirshprung en 4.35/100 (Ano imperforado lo consideramos una anormalidad fuera del estudio ya que si tiene o no fístula puede o no obstruirse). De los pacientes con atresia intestinalla atresia de yeyuno correspondió al 51.67/100 Atresia duodenal 32.23/100 atresia ileal al 12.9/100, atresia múltiples al 3.2/100 y atresia de colon al 0/100 A la mayoría de los neonatos se les realizó resección del área afectada y anastomosis término-terminalo liberación de Bridas, sección de Bandas y operación de Ladd, según el caso, teniendo buena evolución posterior.La morbilidad post-operatoria fue de 19.5/100 que correspondió a Infección de herida operatoria(10.9/100) sépsis generalizada(6.5/100) y abcesos intraabdominales(2.1/100). La mortalidad correspondió al 15/100 de los casos pero debido a causas asociadas y no a la obstrucción u operación per sé. De este estudio concluimos que el manejo de la obstrucción intestinal neonatal es adecuada a pesar de no contar con todos los recursos tecnológicos de los países desarrollados,sobre todo por la estrecha vigilancia que se le da al paciente y por el tratamiento temprano del mismo.El seguimiento se logro en el 85 por ciento de los casos durante 2 años.