Conductive Polymeric Composites Based on Multiwalled Carbon Nanotubes and Linseed Oil Functionalized and Cross-Linked with Diacetylenes from Propargyl Alcohol

Apoyo a Consolidadión de Cuerpos AcadémicosSe presenta la síntesis y saracterización de compuestos poliméricos a base de nanotubos de carbono con aceite de linaza epoxidadoPRODEP-SE

Sensing parameters as a function of the chemical structure and thickness of two poly(styrene)-type based composites with carbon black

Sensing parameters of polymer composite layers were studied as a function of the polymer matrix structure and the initial resistance of the composite layers. Composites of Poly(styrene) and 4-Chloro-poly(styrene) at the same volume fraction of carbon black (8.7% V/V) were prepared by ultrasonic dispersion. Composite layers with different thicknesses and resistances were deposited by spin coating technique on flexible substrates from commercial cellulose acetate foils. Both kind of composite layers with initial resistances of 10, 50 and 100 kΩ were exposed to Acetone, Tetrahydrofuran, Chloroform and Toluene. Results evidenced that selectivity is very dependent on the chemical structure of the polymer matrix and sensitivity to the initial film electrical resistance. PS-based composite series were selective to Tetrahydrofuran whereas that 4ClPS-based composite series were selective to Acetone as expected due to their solubility parameters. For both composite series sensitivity increased for layers with less than 100 kΩ resistances. For all tested solvents 4ClPS-based composites showed higher sensitivities than PS-based composites. The response times for both series were into the range of 2 to 150 s and recovery times were in the range of 30 to 2000 s.SIEA-UAEM, 1025/2014RIF

Conductive Polymer Composites Synthesized from Diacetylene-Functionalized Linseed Oil and MWCNT: Gamma Irradiation and Organic Vapor Sensing

Beca de estancia de Posdoctorado del Dr. Alejandro Ramírez JiménezEpoxidized linseed oil (ELO) was synthesized and functionalized with propargylamine (PA) or 3-ethynylaniline (EA) and the products were crosslinked to obtain the diacetylene-functionalized epoxidized linseed oil polymers which were used as matrices in the preparation of the composites with multiwalled carbon nanotubes (MWCNTs). Electrical resistance at percentages between 4 and 20 wt/wt% of filler was measured and the percolation threshold was calculated, obtaining 1.2 and 1.7% for the composites with EA and PA respectively. Low critical concentration evidenced a good dispersion of the MWCNTs without necessity of any modification. The final products were used in the sensing of acetone, chloroform and ethanol. The electrical resistance changes were measured at different concentrations and the sensibility was calculated. In order to improve stability toward the vapors, composites were irradiated with gamma rays and new sensing was done and compared. The results showed differences in sensibility, selectivity and reproducibility.CONACy

Mechanical properties and fracture behaviour of ODS Steel Friction Stir Welds at variable temperatures

We have assessed the microstructure and the temperature-dependent mechanical behaviour of five bead-on-plate friction stir welds of Oxide Dispersion Strengthened (ODS) steel, produced using systematic changes to the tool rotation and traverse speed. Friction stir welding can potentially retain the fine dispersion of nanoparticles, and therefore also the high-temperature strength and radiation damage resistance of these materials. Tensile testing was carried out on the MA956 base material at a range of temperatures, from room temperature up to 750 °C. The mechanical properties of the welds were investigated via tensile testing at room temperature and at 500 °C, together with micro-hardness testing. The welds exhibited similar strength and ductility to the base material at both testing temperatures as welding caused a partial loss of particle strengthening, alongside an increase in grain boundary strengthening due to a greatly refined grain size in the stir zones. The micro-hardness data revealed a trend of increasing hardness with increasing tool traverse speed or decreasing rotation speed. This was attributed to the smaller grain size and lower nanoparticle number density in the welds created with these parameters. At 500 °C, the yield stress and ultimate tensile stress of the base material and the welds decreased, due to a progressive reduction in both the Orowan-type particle strengthening and the grain boundary strengthening.</p

Enterocutaneous fistulas due to stent migration. How reliable is its use on duodenal benign pathology? a case report

Duodenal stenting has been widely used on malignant pathology on selected patients with poor prognosis and advanced disease. In these last years, there has been a clear ampliation of the clinical applications of endoscopy procedures and stents. Its use on benign pathology is spreading but there is a lack of literature about the complications in this context. The incidence of stent migration is about 10-25% in self-expandable metal stent (SEMS), and 2-5% on covered self-expanding metal stents (CSEMS). We reported a clinical case of a 48 years old patient who developed a duodenal ulcer. The patient was submitted to exploratory laparotomy, with duodenal primary closure of the ulcer. Later, the patient developed a enterocutaneous fistula because of the duodenal leak. It was referred to our third level hospital to the hepatopancreatobiliary surgery service. A new exploratory laparotomy with duodenal exclusion was planned, but it was impossible to access due to frozen abdomen. CSEMS was placed in the duodenal bulb resulting in the resolution of leaking, but the stent could not be removed because of migration. The stent trajectory was followed by abdominal x ray and tomography. The patient developed multiple intestinal an fecal enterocutaneous fistulas. It was submitted to multiples endoscopies, colonoscopies and enteroscopy without any success to reaching it. It was decided to perform a right lumbotomy to extract the prothesis. The stent was surgically removed, a planned stoma was left on the right flank on the extraction site

La emigración internacional, las remesas y el desarrollo económico en México

La migración es un fenómeno que ocurre desde el momento en que el hombre busca nuevas alternativas para mejorar su bienestar social, su aspecto benéfico radica en el flujo de remesas captadas en las regiones expulsoras de mano de obra, las cuales se encuentran concentradas principalmente en las zonas rurales. La tendencia en el uso de las remesas está encaminada hacia la satisfacción de las necesidades básicas, así como a la adquisición de bienes de consumo y a la compra y mejora de la vivienda de las familias de los migrantes. Existen países que tienen flujos migratorios masivos, motivo por el cual reciben flujos importantes de remesas para su contabilidad nacional y en este trabajo se analizan desde la perspectiva de países expulsores y de destino de la mano de obra migrante. Por facilidad de análisis de esta obra los países se agrupan en cinco regiones, a saber; África, Asia, Europa, Latinoamérica y Oceanía. Para nuestro país la captación de divisas por concepto de las exportaciones petroleras es la más importante, pero a partir del año 2000, éstas constantemente se ven amenazadas por los flujos monetarios que ingresan al país por concepto de remesas y que desde el año 2003 se colocaron como la segunda fuente más importante de divisas para México. La necesidad de conocer los efectos de las remesas sobre la conomía mexicana se debe a que representan un flujo monetario que en más del 80% es destinado al autoconsumo y el resto a la inversión o ahorro, lo que sin duda genera burbujas inflacionarias para las regiones que mayoritariamente reciben tales ingresos como en el caso de los estados de Jalisco, Michoacán, Zacatecas, o el mismo Estado de México

Avances en las técnicas de eliminación de marcas de agua visibles basadas en aprendizaje profundo

In recent years, artificial intelligence algorithms have shown great results in different application areas, such as robotics, medical, informatics security, financial services, among others. In the context of digital image processing, the use of deep learning is being applied to remove visible watermarks from the visual content of digital images, to remove the copyright protection of the owners of the images in question. This paper makes a briefly survey of the most recent works that remove visible watermarks employing deep learning, with the purpose of analyzing the current trends that allow designing more robust visible watermarking algorithms against this type of removal tools.En los últimos años los algoritmos de inteligencia artificial han demostrado tener grandes resultados en diferentes áreas de aplicación, tales como robótica, medicina, seguridad informática, finanzas, entre otras. En el contexto de procesamiento digital de imágenes, el uso del aprendizaje profundo está siendo aplicado para remover marcas de agua visibles en imágenes digitales, con la finalidad de eliminar la protección de derechos de autor de los propietarios de las imágenes en cuestión. El presente trabajo realiza una recopilación de los trabajos más recientes que remueven marcas de agua visibles a través de aprendizaje profundo, con la finalidad de analizar las tendencias actuales que permitan diseñar algoritmos de marcado de agua visible más robustos ante este tipo de herramientas de remoción

Evaluating radiological response in pancreatic neuroendocrine tumours treated with sunitinib : comparison of Choi versus RECIST criteria (CRIPNET_ GETNE1504 study)

The purpose of our study was to analyse the usefulness of Choi criteria versus RECIST in patients with pancreatic neuroendocrine tumours (PanNETs) treated with sunitinib. A multicentre, prospective study was conducted in 10 Spanish centres. Computed tomographies, at least every 6 months, were centrally evaluated until tumour progression. One hundred and seven patients were included. Median progression-free survival (PFS) by RECIST and Choi were 11.42 (95% confidence interval [CI], 9.7-15.9) and 15.8 months (95% CI, 13.9-25.7). PFS by Choi (Kendall's τ = 0.72) exhibited greater correlation with overall survival (OS) than PFS by RECIST (Kendall's τ = 0.43). RECIST incorrectly estimated prognosis in 49.6%. Partial response rate increased from 12.8% to 47.4% with Choi criteria. Twenty-four percent of patients with progressive disease according to Choi had stable disease as per RECIST, overestimating treatment effect. Choi criteria predicted PFS/OS. Changes in attenuation occurred early and accounted for 21% of the variations in tumour volume. Attenuation and tumour growth rate (TGR) were associated with improved survival. Choi criteria were able to capture sunitinib's activity in a clinically significant manner better than RECIST; their implementation in standard clinical practice shall be strongly considered in PanNET patients treated with this drug

Circulating Monocytes Exhibit an Endotoxin Tolerance Status after Acute Ischemic Stroke: Mitochondrial DNA as a Putative Explanation for Poststroke Infections

Patients with acute ischemic stroke (AIS) suffer from infections associated with mortality. The relevance of the innate immune system, and monocytes in particular, has emerged as an important factor in the evolution of these infections. The study enrolled 14 patients with AIS, without previous treatment, and 10 healthy controls. In the present study, we show that monocytes from patients with AIS exhibit a refractory state or endotoxin tolerance. The patients were unable to orchestrate an inflammatory response against LPS and expressed three factors reported to control the evolution of human monocytes into a refractory state: IL-1R-associated kinase-M, NFkB2/p100, and hypoxia-inducible factor-1α. The levels of circulating mitochondrial DNA (mtDNA) in patients with AIS correlated with impaired inflammatory response of isolated monocytes. Interestingly, the patients could be classified into two groups: those who were infected and those who were not, according to circulating mtDNA levels. This finding was validated in an independent cohort of 23 patients with AIS. Additionally, monocytes from healthy controls, cultured in the presence of both sera from patients and mtDNA, reproduced a refractory state after endotoxin challenge. This effect was negated by either a TLR9 antagonist or DNase treatment. The present data further extend our understanding of endotoxin tolerance implications in AIS. A putative role of mtDNA as a new biomarker of stroke-associated infections, and thus a clinical target for preventing poststroke infection, has also been identified