CARACTERIZACIÓN MATEMÁTICA DEL REFRIGERANTE R134A PARA LA EVALUACIÓN NUMÉRICA DE EVAPORADORES ( MATHEMATICAL CHARACTERIZATION OF REFRIGERANT R134A FOR THE NUMERICAL EVALUATION OF EVAPORATORS)

En este documento, se presenta un enfoque integral para acelerar los cálculos de las propiedades termofísicas del refrigerante R134a, que incluye las formas funcionales de la parametrización y aspectos de la implementación numérica aplicados a la simulación de componentes en sistemas de refrigeración por compresión de vapor.  Son presentadas un conjunto de expresiones polinomiales que permiten la aproximación de las propiedades termofísicas del fluido en regiones definidas (líquido saturado, vapor saturado y zona bifásica). Las propiedades del refrigerante se calculan a lo largo de las líneas de saturación como una función de la temperatura, en un rango que comprende desde los -10°C hasta los -40°C. ”Los resultados de la caracterización matemática del fluido son evaluadas a través de la simulación numérica de evaporadores con flujo bifásico bajo dos diferentes criterios, el primero resuelve el modelo del intercambiador empleando la aproximación polinomial de las propiedades y el segundo toma los datos del refrigerante directamente de la base de datos estándar NIST REFPROP 2010, presentando un porcentaje de error relativo entre los dos enfoques de cálculo menor al 6%.Palabra(s) clave: códigos, evaporadores, flujos bifásicos, polinomios, R134a. AbstractIn this paper, an integral approach for speeding up thermophysical property calculations is presented, which includes the functional forms of the parameterization and the numerical implementation aspects applied to simulation of components in compression vapor refrigeration systems. A set of polynomial functional forms are presented that allow for approximation of all the thermophysical properties of the working fluid in defined regions (saturated liquid, saturated vapor, and two-phase zone) The properties of the refrigerant are calculated along the saturation lines as a function of temperature, in a range from -10 ° C to -40 ° C. The results of the mathematical characterization of the fluid are evaluated through the numerical simulation of evaporators with two-phase flow under two different criteria, the first solves the model of the exchanger using the polynomial approximation of the properties and the second one takes the data from the refrigerant directly from the standard database NIST REFPROP 2010, presenting a percentage of relative error between the two calculation approaches less than 6%.Keywords: codes, evaporators, polynomial, R134a two – phase flow

Peripheral giant cells granuloma as a rare early manifestation of primary hyperparathyroidism

Primary hyperparathyroidism occurs due to parathyroid adenoma, which as initial presentation in most cases includes recurrent nephrolithiasis (10-25%). Giant cell tumors (GDD) also called osteoclastomas or brown tumors affect the second decade of life and are currently a rare manifestation of primary hyperthyroidism. The incidence of lesion appearance in the maxillary bones is 4.5%. We presented the case of a 36 year old female patient with history of hypertension, who developed an increase in volume in the right maxillary region of 4×3 cm, with incapability of complete occlusion of dental arch, solid dysphagia, biopsy was performed with peripheral giant cells granuloma as a result, PTH serum levels were requested, with result of 1175 pg/ml and serum calcium of 13.24 mg/dl. Parathyroid gammagram was performed with hyperfunctioning parathyroid tissue. Patient underwent a selective parathyroidectomy. She had an adequate postoperative evolution and was discharged without complications. The patient had adequate follow up by head and neck surgery in external consultation, serum calcium 7.66 mg/dl, decrease of volume in right maxillary region to 3×3 cm; pathology report with parathyroid adenoma. Surgical treatment of brown tumor is still pending by the maxillofacial surgery department

Growth kinetics of Fe2B layers formed on the AISI 4150 steel by different approaches

In the present work, the AISI 4150 steel has been pack-borided in the temperature range of 1123-1273 K for a treatmenttime of 2 to 8 h. The mixture of powders containing 20% B4C, 10% KBF4 and 70% SiC has been used for producing a singleboride layer (Fe2B) at the surface of AISI 4150 steel. The presence of Fe2B phase has been confirmed by XRD analysis.The SEM observations have been done to investigate the morphology of boride layers and measure their thicknesses.The cohesion of boride layers has been evaluated by using the Daimler-Benz Rockwell-C indentation technique.The borided sample at 1173 K for 8 h has shown a best cohesion of boride layer to the substrate in comparison to the sampletreated at 1173 K during 2 h. Kinetically, different approaches have been used to estimate the boron diffusion coefficients inthe Fe2B layers and to predict the value of Fe2B layer thickness obtained at 1253 K for a treatment time of 2.5 h. Theestimated values of activation energies for boron diffusion in AISI 4150 steel have been in the range of 193.45 to 199.74 kJmol-1. These values of activation energies have been depended on the diffusion models used. In addition, a good agreementhas been observed between the experimental value of Fe2B layer thickness obtained at 1253 K for 2.5 h with the predictedvalues from these different diffusion models

Growth kinetics of Fe2B layers formed on the AISI 4150 steel by different approaches

277-287In the present work, the AISI 4150 steel has been pack-borided in the temperature range of 1123-1273 K for a treatment time of 2 to 8 h. The mixture of powders containing 20% B4C, 10% KBF4 and 70% SiC has been used for producing a single boride layer (Fe2B) at the surface of AISI 4150 steel. The presence of Fe2B phase has been confirmed by XRD analysis. The SEM observations have been done to investigate the morphology of boride layers and measure their thicknesses. The cohesion of boride layers has been evaluated by using the Daimler-Benz Rockwell-C indentation technique. The borided sample at 1173 K for 8 h has shown a best cohesion of boride layer to the substrate in comparison to the sample treated at 1173 K during 2 h. Kinetically, different approaches have been used to estimate the boron diffusion coefficients in the Fe2B layers and to predict the value of Fe2B layer thickness obtained at 1253 K for a treatment time of 2.5 h. The estimated values of activation energies for boron diffusion in AISI 4150 steel have been in the range of 193.45 to 199.74 kJ mol-1. These values of activation energies have been depended on the diffusion models used. In addition, a good agreement has been observed between the experimental value of Fe2B layer thickness obtained at 1253 K for 2.5 h with the predicted values from these different diffusion models

Highly Regio- and Stereoselective Diels-Alder Cycloadditions via Two-Step and Multicomponent Reactions Promoted by Infrared Irradiation under Solvent-Free Conditions

Infrared irradiation promoted the Diels-Alder cycloadditions of exo-2-oxazolidinone dienes 1–3 with the Knoevenagel adducts 4–6, as dienophiles, leading to the synthesis of new 3,5-diphenyltetrahydrobenzo[d]oxazol-2-one derivatives (7, 9, 11 and 13–17), under solvent-free conditions. These cycloadditions were performed with good regio- and stereoselectivity, favoring the para-endo cycloadducts. We also evaluated the one-pot three-component reaction of active methylene compounds 20, benzaldehydes 21 and exo-2-oxazolidinone diene 2 under the same reaction conditions. A cascade Knoevenagel condensation/Diels-Alder cycloaddition reaction was observed, resulting in the final adducts 13–16 in similar yields. These procedures are environmentally benign, because no solvent and no catalyst were employed in these processes. The regioselectivity of these reactions was rationalized by Frontier Molecular Orbital (FMO) calculations

Intake of Spineless Cladodes of Opuntia ficus-indica During Late Pregnancy Improves Progeny Performance in Underfed Sheep

13 Pág.The present study tested whether feeding ewes during the last third of pregnancy with cladodes of Opuntia (untreated or protein-enriched), as an alternative to alfalfa hay, would improve milk yield as well as the pre- and post-natal growth of their lambs. Sixty mature Rambouillet ewes and their progeny were randomly allocated among three nutritional treatments: (i) Control, fed alfalfa; (ii) Opuntia, fed untreated cladodes; (iii) E-Opuntia, fed protein-enriched cladodes (pre-treated with urea and ammonium sulphate). Birth weight did not differ among treatments (p > 0.05) but Control ewes produced more milk than both groups of Opuntia-fed ewes (p 0.05) because lambs from E-Opuntia-fed ewes grew faster (p < 0.01) and were heavier at weaning (p < 0.05) than lambs from the other two groups. We conclude that Opuntia (with or without protein enrichment) can be used as an alternative to alfalfa hay for feeding ewes during the last third of pregnancy and therefore reduce production costs under extensive conditions in arid and semiarid regions. Moreover, protein-enriched Opuntia appears to improve postnatal lamb growth.The present study was funded by the National Institute for Research in Forestry, Agriculture and Livestock (INIFAP/project-10561934075).Peer reviewe

Global political responsibility for the conservation of albatrosses and large petrels

Migratory marine species cross political borders and enter the high seas, where the lack of an effective global management framework for biodiversity leaves them vulnerable to threats. Here, we combine 10,108 tracks from 5775 individual birds at 87 sites with data on breeding population sizes to estimate the relative year-round importance of national jurisdictions and high seas areas for 39 species of albatrosses and large petrels. Populations from every country made extensive use of the high seas, indicating the stake each country has in the management of biodiversity in international waters. We quantified the links among national populations of these threatened seabirds and the regional fisheries management organizations (RFMOs) which regulate fishing in the high seas. This work makes explicit the relative responsibilities that each country and RFMO has for the management of shared biodiversity, providing invaluable information for the conservation and management of migratory species in the marine realm

Compartiendo saberes de educación y humanidades

Los capítulos referentes a este libro tratan diversos temas tales como: 1) la construcción de los estudiantes de la licenciatura en químico farmacéutico biólogo el juicio valorativo y personaI deI significado en su desarroIIo profesionaI desde eI punto de vista axiológico, 2) se realiza un estudio en el Plantel Cuauhtémoc con Ia finaIidad de orientar a Ia comunidad estudiantiI aI tratamiento deI probIema de los residuos sólidos desde su etapa de diagnóstico hasta una propuesta de solución de la problemática, 3) se analiza como a nivel básico se construye el conocimiento y la participación del género en los estudiantes, en donde se observa que el papel del docente es un promotor importante, 4) es un tema que actualmente está causando mucho interés tanto en la educación como el la población en general, las redes sociales que actuaImente ese consideran un medio de comunicación con mucha influencia dentro de la sociedad, 5) se adentra al campo de la psicología y la tanatología ante los recursos resilientes que presentan las familias ante la muerte de un hijo, 6) es una investigación dedicada a identificar Ias diferentes percepciones que tienen las mujeres y los hombres en relación a la felicidad y la desdicha dentro del matrimonio, 7) es un análisis Transgeneracional para aportar las referencias familiares que permiten la permanencia del abuso sexual infantil en tres generaciones, de las cuales en la última generación se rompe ese secreto avallazador al romper el silencio, 8) es un ensayo acerca del juego terapéutico desde el punto de vista psicoanalítico, en el que se advierte ese juego en el que entra el paciente con el psicoanalista, 9) la metodología de la observación para la integración de la pericial en psicología, en donde se denotan desde la parte jurídica como se fundamente esta pericial y fortalece el logro del dictamen para tener un buen dictamen, 10) es una propuesta de construcción y validez del instrumento BP-22 Bienestar Psicológico en el ámbito de la educación superior, 11) se identifica a Ios procesos eIectoraIes como complicados, de tal manera que abre un panorama al marketing de los partidos políticos para conducir la voluntad ciudadana, y además ayuda al posicionamiento de los partidos, 12) aporta una base sobre Ios procesos identificatorios en eI movimiento estudiantiI de Ia UNAM deI año de I999, pIanteándoIo desde dos ejes de análisis: las identidades universitarias y el apartado del texto, que permiten configurar eI movimiento estudiantiI como un acontecimiento capaz de generar articulaciones nuevas de solidaridad. AI finaI deI Iibro se encuentran Ias síntesis curricuIares de cada uno de los autores, que aportaron sus investigaciones para la integración y generación de nuevos aportes científicos.Como su nombre lo indica COMPARTIENDO SABERES DE EDUCACIÓN Y HUMANIDADES, es un Iibro que denota eI deseo de integrar conocimiento para la comunidad estudiantil, llevarlos al interés de la investigación a través de la participación de los investigadores de diferentes áreas como: la educación, las ciencias sociales y las humanidades. Que les permite tener no solo un espacio en la difusión de los avances de sus estudios, sino que además permite el generar el interés de quién lo lee en diferentes formas de investigación, se encuentran estudios tanto cualitativos como cuantitativos, desde descriptivos hasta un nivel de intervención en la práctica de estas áreas.Universidad Autónoma del Estado de méxic

Performance of CMS muon reconstruction in pp collision events at sqrt(s) = 7 TeV

The performance of muon reconstruction, identification, and triggering in CMS has been studied using 40 inverse picobarns of data collected in pp collisions at sqrt(s) = 7 TeV at the LHC in 2010. A few benchmark sets of selection criteria covering a wide range of physics analysis needs have been examined. For all considered selections, the efficiency to reconstruct and identify a muon with a transverse momentum pT larger than a few GeV is above 95% over the whole region of pseudorapidity covered by the CMS muon system, abs(eta) < 2.4, while the probability to misidentify a hadron as a muon is well below 1%. The efficiency to trigger on single muons with pT above a few GeV is higher than 90% over the full eta range, and typically substantially better. The overall momentum scale is measured to a precision of 0.2% with muons from Z decays. The transverse momentum resolution varies from 1% to 6% depending on pseudorapidity for muons with pT below 100 GeV and, using cosmic rays, it is shown to be better than 10% in the central region up to pT = 1 TeV. Observed distributions of all quantities are well reproduced by the Monte Carlo simulation.Comment: Replaced with published version. Added journal reference and DO