Density Functional Theory-Based Approaches to Improving Hydrogen Storage in Graphene-Based Materials.

Various technologies have been developed for the safe and efficient storage of hydrogen. Hydrogen storage in its solid form is an attractive option to overcome challenges such as storage and cost. Specifically, hydrogen storage in carbon-based structures is a good solution. To date, numerous theoretical studies have explored hydrogen storage in different carbon structures. Consequently, in this review, density functional theory (DFT) studies on hydrogen storage in graphene-based structures are examined in detail. Different modifications of graphene structures to improve their hydrogen storage properties are comprehensively reviewed. To date, various modified graphene structures, such as decorated graphene, doped graphene, graphene with vacancies, graphene with vacancies-doping, as well as decorated-doped graphene, have been explored to modify the reactivity of pristine graphene. Most of these modified graphene structures are good candidates for hydrogen storage. The DFT-based theoretical studies analyzed in this review should motivate experimental groups to experimentally validate the theoretical predictions as many modified graphene systems are shown to be good candidates for hydrogen storage.

Load Distribution on PET-G 3D Prints of Honeycomb Cellular Structures under Compression Load.

Energy resulting from an impact is manifested through unwanted damage to objects or persons. New materials made of cellular structures have enhanced energy absorption (EA) capabilities. The hexagonal honeycomb is widely known for its space-filling capacity, structural stability, and high EA potential. Additive manufacturing (AM) technologies have been effectively useful in a vast range of applications. The evolution of these technologies has been studied continuously, with a focus on improving the mechanical and structural characteristics of three-dimensional (3D)-printed models to create complex quality parts that satisfy design and mechanical requirements. In this study, 3D honeycomb structures of novel material polyethylene terephthalate glycol (PET-G) were fabricated by the fused deposition modeling (FDM) method with different infill density values (30%, 70%, and 100%) and printing orientations (edge, flat, and upright). The effectiveness for EA of the design and the effect of the process parameters of infill density and layer printing orientation were investigated by performing in-plane compression tests, and the set of parameters that produced superior results for better EA was determined by analyzing the area under the curve and the welding between the filament layers in the printed object via FDM. The results showed that the printing parameters implemented in this study considerably affected the mechanical properties of the 3D-printed PET-G honeycomb structure. The structure with the upright printing direction and 100% infill density exhibited an extension to delamination and fragmentation, thus, a desirable performance with a long plateau region in the load-displacement curve and major absorption of energy.

The two sides of superior mesenteric artery syndrome treatment: conservative or surgical management?

INTRODUCTION: Superior mesenteric artery syndrome (SMAS) is a rare condition characterized by vascular compression of the duodenum. There is controversy regarding the optimal treatment. CASE REPORT: In case 1, we describe the case of a 21-year-old woman (body mass index -BMI- 16.9 kg/m2) with high-level obstructive symptoms three months prior, with computed tomography scan (TC) showing a superior mesenteric artery aorta angle (SMAA) of 13º and compression of the third portion of the duodenum (D3), for this reason a nasojejunal tube was placed for enteral feeding. In case 2, enteral nutrition was initiated for feeding a 17-year-old female with anorexia nervosa (BMI 8.3 kg/m2). She presented macrohematuria, vomiting, epigastralgia, abdominal distension and acute abdomen when oral feeding was reinitiated. TC reported a SMAA of 15º, in addition to compression of the left renal vein (Nutcracker syndrome) and gastro duodenal expansion, surgical management was necessary. DISCUSSION: Both cases had favorable evolution, being the nutritional support fundamental. SMAS should be suspected in all people with high-level obstructive symptoms and recent weight loss.

Calidad de atención y relaciones familiares en la asistencia a los controles del servicio de consulta externa / Quality of care and family relations in assisting controls outpatient service

Para recolectar la información se realizaron 100 visitas domiciliarias; se aplicaron 2 instrumentos para c/u, (calidad de atención y apgar familiar); para la tabulación, se utilizaron tablas de contingencia; la información se presento a razón de disparidad, determinando la fuerza de asociación entre los factores de riesgo estudiados, de acuerdo con las hipótesis planteadas. Se pudo determinar que la insatisfacción de los usuarios para la calidad de los servicios ofertados por el H.M.R.S. es un factor predisponente para inasistencia a los controles por consulta externa. Se identificó que no hay evidencia estadísticamente, que el presentar insatisfacción, representa un factor asociado para la inasistencia a tratamiento por consulta externa. Para la funcionalidad familiar, se demostró que el 96.7% de cada 100 casos presentan disfuncionalidad familiar, y un 89.7% de cada 100 controles también presentan disfunción familiar, demostrando que esta variable es una característica principal de los pacientes mentales en general. Para concluir, la calidad de atención como la funcionalidad familiar, representan un factor predisponente a presentar inasistencia, pero no son la principal causa por la cual los usuarios del Hospital Mental Rudesindo Soto ( HMRS) no acuden a los controles programados por consulta externa de acuerdo a lo investigado.

For the harvesting of the information 100 domiciliary visits were realised; 2 instruments for c/u were applied, (quality of attention and to apgar familiar); for the tabulation, contingency tables were used, and the information I appear at the rate of disparity, determining the force of association between the studied factors of risk, in agreement with the raised hypotheses. With the investigation it was possible to be determined that the dissatisfaction of the users for the quality of the services supplied by the H.M.R.S is a factor prearranger for inasistencia to the controls by external consultation. I identify myself that there is no evidence statistically, that presenting/displaying dissatisfaction, represents a factor associated for the inasistencia treatment by external consultation. For the familiar functionality, one demonstrated that the 96,7% of each 100 cases present/display familiar disfunctionality, and 89,7% of each 100 controls also present/display familiar dysfunction, demonstrating that this variable is a basic characteristics of the mental patients generally. In order to conclude, the quality of attention like the familiar functionality, represents a factor prearranger to present/display inasistencia, but they are not the main cause by which the users of the HMRS do not go to the controls.

Transición parasitaria a Blastocystis hominis en niños de la zona centro del estado de Guerrero, México / Parasitic transition to Blastocystis hominis in children from center zone of Guerrero state, Mexico

Blastocystis hominis es un organismo emergente cuya prevalencia se ha incrementado en los últimos años. La frecuencia en México va de 4,0 por ciento a 62 por ciento, sin reportes previos en el estado de Guerrero. La población estudiada fueron tres localidades del estado de Guerrero: Chilpancingo, Petaquilla y Tixtla en un total de 1.138 niños preescolares y escolares, de ambos sexos. Mediante tres técnicas coproparasitóscopicas (CPS): examen directo, concentración por flotación de Faust y cultivo de Barret, se detectaron un total de 38 por ciento de niños parasitados y B. hominis ocupó el primer lugar con el 61 por ciento de los CPS positivos. El 90 por ciento de los casos fueron parasitosis única. El 58 por ciento de los niños aparentemente sanos y con B. hominis declararon tener algún síntoma gastrointestinal. La asociación de B. hominis con dolor abdominal y beber agua de la llave tuvo diferencia significativa. Proponemos una transición parasitaria a B. hominis como principal parásito del hombre, como resultado de las medidas de control para las parasitosis intestinales.

Blastocystis hominis is an enteric emergen organism found in human it's prevalence has been increasing in the lasts years. The frequency in Mexico is from 4.0 percent to 62 percent, without reports in the Guerrero state. The aim of this study was to inform the parasitic transition to B. hominis in the Central Zone of Guerrero state. The population in this study were three communities of Guerrero state: Chilpancingo, Petaquilla and Tixtla in a total of 1,138 preschools and schools children of both sexs. Three parasitological tests were used for detection of the parasite in stool specimens: micrscopy of direct smears, concentration and flotation technique and serum-solution saline culture. Global prevalence of parasites was of 38 percent and B. hominis was the principal parasite with 61 percent on the positive tests. The 90 percent were only B. hominis and 10 percent with others parasites. A total of 58 percent of the children healthy with B. hominis declarated have gastrointestinal symptoms. The association ofB. hominis with abdominal pain and drinking taste water had significant difference. We propuse a parasitic transition to B. hominis as principal human parasite, this can be the result of man-made intervention in the intestinal parasitosis control.

Manifestaciones oftalmológicas de las facomatosis en niños / Ophthalmologic features of the phakomatoses in children

Las facomatosis son un grupo de enfermedades que afectan piel, sistema nervioso central, vasos sanguíneos y globo ocular. La mayoría de ellas se presentan desde la niñez. Para su diagnóstico es necesario un grupo multidisciplinario, incluyendo al oftalmólogo pediatra. En este estudio retrospectivo se encontraron las manifestaciones oculares más frecuentes que se observan en cada entidad. En la neurofibromatosis tipo 1, los nódulos de Lisch se observaron en 74 por ciento de los casos y neorofibroma plexiforme del párpado en 10 por ciento. En la esclerosis tuberosa el dato más frecuente fue la hipopigmentación de iris en el 10 por ciento de los pacientes. El glaucoma estuvo presente en 60 por ciento de los casos con síndrome de Sturge Weber. Por último en la ataxia telangiectasia el signo ocular relevante para el diagnóstico fue la telangiectasia conjuntival en 85 por ciento de los pacientes. No se registro ningún paciente con síndrome de von Hippel Lindau ni síndrome de Wyburn Mason

Síndrome de Freeman-Sheldon. Presentación de un caso / Freeman-Sheldon Syndrome. A case report

Se presenta el caso de un niño con síndrome de Freeman Sheldon o síndrome del niño silbador. Esta entidad es rara y poco frecuente que presente manifestaciones oculares. Se señalan tanto las alteraciones sistémicas como oftalmológicas del caso, así como lo descrito en la literatura