Analysis of Modified Mechanical Properties in the Repair by SMAW Welding of Plow Discs in Andean Agricultural Areas

The objective of this contribution is to analyze the results of the technical studies of mechanical properties in standard plow discs, after their repair by manual arc welding with a SMAW coated electrode, commonly used in tillage tasks in Andean agricultural areas. For the repair process, the available, convenient, and easily acquired resources are implemented, such as consumables, equipment, and accessories necessary for the procedure. The nature of the base material was initially determined, by means of a spark spectrometry study for the case of worn plow discs, in such a way that the characteristic alloying elements of AISI-SAE 1340 steel are evident. The base of the original material allows defining and implementing essential and non-essential variables of the SMAW welding process according to AWS D1.1 and D14.3; therefore, the lap joint is designed, comprising of a worn disc plus similar sacrificial metals of identical conditions. As a conventional part of the welding processes, the quality control of the welds is carried out by means of penetrating inks under the ASTM E-165 standard, the respective measurements of the mechanical properties achieved, maintain analog factory hardness values of 37 HRC and increases the hardenability of the lap-type weld bead. Finally, it is concluded that the repair process contributes to a sustainable and efficient alternative that preserves the average hardness and improves hardenability, which are necessary to withstand the operational context that induces the typical premature wear of clayey and humid soils. Keywords: Hardness, hardenability, plow disc, welding, agricultural soil. Resumen El presente aporte tiene el objetivo de analizar los resultados de los estudios técnicos de propiedades mecánicas en discos de arado estándar, posterior a su reparación por soldadura de arco manual con electrodo revestido SMAW, de uso común en labores de labranza de zonas agrícolas andinas. Para el proceso de la reparación, se implementan los recursos disponibles, convenientes y de fácil adquisición, como consumibles, equipos y accesorios necesarios para el procedimiento. Se determina inicialmente la naturaleza del material base, mediante un estudio de espectrometría de chispa para el caso de discos de arado desgastados, de tal manera se evidencia los elementos aleantes característicos del acero AISI-SAE 1340. La base del material original permite definir e implementar variables esenciales y no esenciales del proceso de soldadura SMAW según AWS D1.1 y D14.3, por lo tanto, se diseña la junta de traslape, que comprende de un disco desgastado más metales similares de sacrificio de condiciones idénticas. Como parte convencional de los procesos de soldadura se realiza el control de calidad de las soldaduras mediante tintas penetrantes bajo la normativa ASTM E-165, las respectivas mediciones de las propiedades mecánicas conseguidas, mantienen valores de dureza de fábrica 37 HRC análogos y la templabilidad aumenta en el cordón de soldadura de tipo traslape. Finalmente, se concluye que el proceso de reparación contribuye con una alternativa sustentable y eficiente que conserva la dureza promedio y mejora la templabilidad, necesaria para soportar el contexto operacional que induce el desgaste prematuro típico de terrenos arcillosos y húmedos. Palabras Clave: Dureza, templabilidad, disco de arado, soldadura, suelo agrícola

Situación de los recursos hídricos en Nicaragua

Nicaragua, conocido como el país de lagos y volcanes, es abundante en recursos hídricos superficiales y subterráneos. Sus dos grandes lagos de origen tectónico, Xolotlán de 1.040 km2 y Cocibolca de 8.200 km2; sus 21 cuencas hidrográficas con un potencial de 152.596 millones de m3; un sinnúmero de lagunas de origen volcánico y dos lagos artificiales forman parte de sus riquezas. En la Región del Pacífico se desarrollan los acuíferos de mayor potencial mientras que en la región Atlántica la abundancia de recursos hídricos superficiales ha relegado el desarrollo de los subterráneos. En esta zona del Pacífico se concentra la mayor densidad poblacional y es donde se realiza la mayor actividad agrícola e industrial del país; lo que ha conllevado, en algunos casos a la explotación excesiva de los acuíferos, y a una degradación progresiva de la calidad del agua, que amenaza la disponibilidad futura de agua para usos vitales de la población. Se han encaminado esfuerzos en la solución a estos problemas, con un enfoque integral de cuencas, que actualmente está poco a poco resultando en conservación y restauración de las recursos hídricos

Consultoría integral en una empresa de instalación y mantenimiento de aire acondicionado y proyectos eléctricos en el municipio de Zapopan

ITESO, A.C

Identification of latexin by a proteomic analysis in rat normal articular cartilage

<p>Abstract</p> <p>Background</p> <p>Osteoarthritis (OA) is characterized by degeneration of articular cartilage. Animal models of OA induced are a widely used tool in the study of the pathogenesis of disease. Several proteomic techniques for selective extraction of proteins have provided protein profiles of chondrocytes and secretory patterns in normal and osteoarthritic cartilage, including the discovery of new and promising biomarkers. In this proteomic analysis to study several proteins from rat normal articular cartilage, two-dimensional electrophoresis and mass spectrometry (MS) were used. Interestingly, latexin (LXN) was found. Using an immunohistochemical technique, it was possible to determine its localization within the chondrocytes from normal and osteoarthritic articular cartilage.</p> <p>Results</p> <p>In this study, 147 proteins were visualized, and 47 proteins were identified by MS. A significant proportion of proteins are involved in metabolic processes and energy (32%), as well as participating in different biological functions including structural organization (19%), signal transduction and molecular signaling (11%), redox homeostasis (9%), transcription and protein synthesis (6%), and transport (6%). The identified proteins were assigned to one or more subcellular compartments.</p> <p>Among the identified proteins, we found some proteins already recognized in other studies such as OA-associated proteins. Interestingly, we identified LXN, an inhibitor of mammalian carboxypeptidases, which had not been described in articular cartilage. Immunolabeling assays for LXN showed a granular distribution pattern in the cytoplasm of most chondrocytes of the middle, deep and calcified zones of normal articular cartilage as well as in subchondral bone. In osteoarthritic cartilage, LXN was observed in superficial and deep zones.</p> <p>Conclusions</p> <p>This study provides the first proteomic analysis of normal articular cartilage of rat. We identified LXN, whose location was demonstrated by immunolabeling in the chondrocytes from the middle, deep and calcified zones of normal articular cartilage, and superficial and deep zones of osteoarthritic cartilage.</p

Caracterización química de la Fibra de Coco (Cocus nucifera L.) de México utilizando Espectroscopía de Infrarrojo (FTIR)

There is a growing interest in products with less environmental impact, this makes the use of natural fibers a viable alternative. The use of materials of biological origin is increasing in an attempt to reduce the amount of thermoplastic polymers from non-renewable sources. In this framework, the work characterizes the chemical characterization of coconut fiber (Cocus nucifera L.), by means of infrared spectroscopy (FTIR), and the spectra of the fibers of coconut, from two important growing sites, the Acapulco and San Jerónimo de Juárez regions, in the state of Guerrero, Mexico, the results obtained are compared with other spectra of other natural fibers, due to the high content of lignin, properties are attributed viscoelastic, by which it is inferred that when the fibers are subjected to a compression load or an impact force, the amorphous region (lignin) functions as a buffer and is resilient to the applied phenomena, a desirable characteristic in packaging materials, this proves that the coconut fiber with natural binder, could be a proposal to be used as packing material in packaging, the data corroborate a high percentage of cellulose and lignin present in the samples studied.Existe un creciente interés en productos con menor impacto ambiental, esto hace que el uso de fibras naturales sea una alternativa viable. El uso de materiales de origen biológico está aumentando en un intento de reducir la cantidad de polímeros termoplásticos de fuentes no renovables. En este marco se presenta el trabajo caracterización química de la fibra de coco (Cocus nucifera L.), mediante espectroscopía de infrarrojo (FTIR) , y se muestran los espectros de las fibras de coco, de dos lugares de cultivo importantes, la región de Acapulco y San Jerónimo de Juárez, en el estado de Guerrero, México , los resultados obtenidos son comparados con otros espectros de otras fibras naturales, debido al alto contenido de lignina se le atribuyen propiedades viscoelásticas, por lo que se infiere que al ser sometidas las fibras a una carga de compresión o una fuerza de impacto, la región amorfa (lignina) funciona como amortiguador y es resiliente a los fenómenos aplicados, una característica deseable en los materiales de embalaje, esto prueba que la fibra de coco con aglomerante natural, pudiera ser una propuesta para usarse como material de relleno en embalajes, los datos corroboran un alto porcentaje de celulosa y lignina presenteen las muestras estudiadas

The nature of dust in compact Galactic planetary nebulae from Spitzer spectra

We present the Spitzer/IRS spectra of 157 compact Galactic PNe. These young PNe provide insight on the effects of dust in early post-AGB evolution, before much of the dust is altered or destroyed by the hardening stellar radiation field. Most of the selected targets have PN-type IRS spectra, while a few turned out to be misclassified stars. We inspected the group properties of the PN spectra and classified them based on the different dust classes (featureless, carbon-rich dust; oxygen-rich dust; mixed-chemistry dust) and subclasses (aromatic and aliphatic; crystalline and amorphous). All PNe are characterized by dust continuum and more than 80% of the sample shows solid state features above the continuum, in contrast with the Magellanic Cloud sample where only ~40% of the entire sample displays solid state features; this is an indication of the strong link between dust properties and metallicity. The Galactic PNe that show solid state features are almost equally divided among the CRD, ORD, and MCD. We analyzed dust properties together with other PN properties and found that (i) there is an enhancement of MCD PNe toward the Galactic center; (ii) CRD PNe could be seen as defining an evolutionary sequence, contrary to the ORD and MCD PNe; (iii) C- and O-rich grains retain different equilibrium temperatures, as expected from models; (iv) ORD PNe are highly asymmetric and CRD PNe highly symmetric; point-symmetry is statistically more common in MCD. We find that the Galactic Disk sample does not include MCD PNe, and the other dust classes are differently populated from high to low metallicity environments. The MCPNe seem to attain higher dust temperatures at similar evolutionary stages, in agreement with the observational findings of smaller dust grains in low metallicity interstellar environments.Comment: The Astrophysical Journal, in press (76 pages, 36 figures and 6 Tables

A Detailed Look at Chemical Abundances in Magellanic Cloud Planetary Nebulae. I. The Small Magellanic Cloud

We present an analysis of elemental abundances of He, N, O, Ne, S, and Ar in Magellanic Cloud planetary nebulae (PNe), and focus initially on 14 PNe in the Small Magellanic Cloud (SMC). We derived the abundances from a combination of deep, high dispersion optical spectra, as well as mid-infrared (IR) spectra from the Spitzer Space Telescope. A detailed comparison with prior SMC PN studies shows that significant variations among authors of relative emission line flux determinations lead to systematic discrepancies in derived elemental abundances between studies that are >~0.15 dex, in spite of similar analysis methods. We used ionic abundances derived from IR emission lines, including those from ionization stages not observable in the optical, to examine the accuracy of some commonly used recipes for ionization correction factors (ICFs). These ICFs, which were developed for ions observed in the optical and ultraviolet, relate ionic abundances to total elemental abundances. We find that most of these ICFs work very well even in the limit of substantially sub-Solar metallicities, except for PNe with very high ionization. Our abundance analysis shows enhancements of He and N that are predicted from prior dredge-up processes of the progenitors on the AGB, as well as the well known correlations among O, Ne, S, and Ar that are little affected by nucleosynthesis in this mass range. We identified MG_8 as an interesting limiting case of a PN central star with a ~3.5 M_sun progenitor in which hot-bottom burning did not occur in its prior AGB evolution. We find no evidence for O depletion in the progenitor AGB stars via the O-N cycle, which is consistent with predictions for lower-mass stars. We also find low S/O ratios relative to SMC H_II regions, with a deficit comparable to what has been found for Galactic PNe.Comment: 9 figures, 6 tables; to be published in Ap

Exact propagators for atom-laser interactions

A class of exact propagators describing the interaction of an $N$-level atom with a set of on-resonance $\delta$-lasers is obtained by means of the Laplace transform method. State-selective mirrors are described in the limit of strong lasers. The ladder, V and $\Lambda$ configurations for a three-level atom are discussed. For the two level case, the transient effects arising as result of the interaction between both a semi-infinite beam and a wavepacket with the on-resonance laser are examined.Comment: 13 pages, 6 figure