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Search Results: 1 - 10 of 7381 matches for " JHON FABIO CARDONA "
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DISE O DE UN BANCO DE PRUEBAS DE DESALINEAMIENTO Y DESBALANCEO MECANICO
HéCTOR áLVARO GONZáLEZ,JHON FABIO CARDONA,GUSTAVO A. MONROY
Scientia Et Technica , 2005,
Abstract: En este articulo se describe un banco de pruebas de Laboratorio para el desalineamiento y desbalanceo mecánico de partes rotodinámicas, y presenta los elementos de dise o mas importantes del mismo. El banco será construido para el Laboratorio de Mecatrónica de la Escuela de Tecnología Mecánica de la Universidad Tecnológica de Pereira.
ELECTRICAL PROPERTIES OF Cr/CrN NANO-MULTILAYERS PRODUCED BY THE UNBALANCED MAGNETRON SPUTTERING TECHNIQUE
MARULANDA CARDONA,DIANA MARITZA; OLAYA FLOREZ,JHON JAIRO;
DYNA , 2011,
Abstract: chromium nitride (crn) films have been applied to several steels as protective coatings against wear and corrosion due to their excellent mechanical properties and corrosion resistance, and in the electronic field these films are commonly used due to their low electrical resistivity. however, it has been found that multilayers combining metal/ceramic films could enhance mechanical and electrical properties compared with their monolayer counterparts, due to the higher amount and interaction between interfaces. in this work, cr/crn nano-multilayers have been produced through the unbalanced magnetron sputtering technique with three different degrees of unbalance, in order to study the influence of this parameter on electrical properties. cr/crn multilayers with approximately 1 μm of total thickness and a bilayer period (λ) of 200 nm, 100 nm, and 20 nm were produced at room temperature on h13 steel and silicon (100); and their microstructure and electrical properties as a function of the magnetic field were evaluated. the phase formation was characterized through x-ray diffraction, and results presented (111) and (200) preferred orientations for all the multilayers. cross section images were obtained through scanning electron microscopy and a multilayer structure can be clearly seen.
Caracterización de genotipos de fríjol ( Phaseolus vulgaris ) por su resistencia a Thrips palmi (Thysanoptera: Thripidae)
DIAZ M,JHON; CARDONA M,CESAR; BUENO,JUAN MIGUEL;
Revista Colombiana de Entomología , 2003,
Abstract: to identify sources of resistance to thrips palmi karny in dry beans ( phaseolus vulgaris l.), three field trials were conducted in pradera (cauca valley, colombia) under heavy natural infestation. in the first trial, 38 genotypes were characterized for resistance to t. palmi in a completely randomized block design. in the other two trials, nine genotypes were used in a split-plot design. in one case, the main plot was fertilization level; while in the other, chemical protection was the main plot. variation in t. palmi attack was detected in the genotypes tested. thrip populations showed an aggregate pattern of distribution and had a significant effect on damage levels to plants. damage negatively affected reproductive adaptation and yield plants. genotypes brunca, bh 21134-5, emp 486, bat 477, feb 115 y bh 21134-60 showed resistance to thrips in the experiments. fertilization levels did not have an effect on resistance expression. losses due to thrips damage ranged from 11,9% to 65,1%. feb 115, bh 21134-5, emp 486, bh 21134-60 and brunca were below the average susceptibility index of the experiment; genotypes with low susceptibility indexes may have tolerante to damage and suffer lower losses. further work is needed in order to elucidate the mechanisms of resistance to thrips in resistant genotypes.
Caracterización de genotipos de fríjol ( Phaseolus vulgaris ) por su resistencia a Thrips palmi (Thysanoptera: Thripidae) Characterization of dry bean genotypes ( Phaseolus vulgaris )for resistance to Thrips palmi (Thysanoptera: Thripidae)
JHON DIAZ M,CESAR CARDONA M,JUAN MIGUEL BUENO
Revista Colombiana de Entomología , 2003,
Abstract: Con el fin de identificar fuentes de resistencia a Thrips palmi Karny en fríjol ( Phaseolus vulgaris L.) se hicieron tres experimentos en condiciones de campo e infestación natural en el municipio de Pradera (Valle del Cauca, Colombia). En el primero, se caracterizaron por resistencia al insecto 38 genotipos en un dise o de bloques al azar. En los otros dos experimentos, se utilizaron nueve genotipos en dise os de parcelas divididas; en un caso la parcela mayor fue niveles de fertilización, y en el otro niveles de protección química. Se detectó variabilidad al ataque de T. palmi en los genotipos evaluados. La distribución del insecto en el campo fue agregada. Las poblaciones estuvieron directamente relacionadas con el da o causado a la planta y, éste incidió negativamente en la adaptación reproductiva y en los rendimientos. Los genotipos Brunca, BH 21134-5, EMP 486, BAT 477, FEB 115 y BH 21134-60 mostraron resistencia al insecto a través de los experimentos. Sin embargo, es necesario hacer otros estudios para conocer cuál o cuáles mecanismos de resistencia (antixenosis, antibiosis o tolerancia) están presentes en ellos. No hubo efecto de las condiciones nutricionales en la expresión de resistencia. Las pérdidas causadas por T. palmi oscilaron entre 11,9 y 65,1%. FEB 115, BH 21134-5, EMP 486, BH 21134-60 y Brunca estuvieron por debajo del índice de susceptibilidad promedio del experimento; genotipos con índices bajos tienen mayor tolerancia al da o y menores pérdidas. Es necesario realizar más trabajos de investigación con el fin de descifrar los mecanismos de resistencia a los trips en genotipos resistentes. To identify sources of resistance to Thrips palmi Karny in dry beans ( Phaseolus vulgaris L.), three field trials were conducted in Pradera (Cauca Valley, Colombia) under heavy natural infestation. In the first trial, 38 genotypes were characterized for resistance to T. palmi in a completely randomized block design. In the other two trials, nine genotypes were used in a split-plot design. In one case, the main plot was fertilization level; while in the other, chemical protection was the main plot. Variation in T. palmi attack was detected in the genotypes tested. Thrip populations showed an aggregate pattern of distribution and had a significant effect on damage levels to plants. Damage negatively affected reproductive adaptation and yield plants. Genotypes Brunca, BH 21134-5, EMP 486, BAT 477, FEB 115 y BH 21134-60 showed resistance to Thrips in the experiments. Fertilization levels did not have an effect on resistance expression. Losses due to Thr
ELECTRICAL PROPERTIES OF Cr/CrN NANO-MULTILAYERS PRODUCED BY THE UNBALANCED MAGNETRON SPUTTERING TECHNIQUE
DIANA MARITZA MARULANDA CARDONA,JHON JAIRO OLAYA FLOREZ
DYNA , 2011,
Abstract: Peliculas de nitruro de cromo (CrN) se han aplicado como recubrimientos protectores contra el desgaste y la corrosion debido a sus excelentes propiedades mecanicas y alta resistencia a la corrosion, y en el campo electronico debido a su baja resistividad. Sin embargo, se ha encontrado que las multicapas que combinan peliculas metal/ceramico podrian mejorar las propiedades en comparacion a sus contrapartes en monocapa debido al aumento e interaccion entre interfaces. En este trabajo se produjeron nano-multicapas de Cr/CrN a traves de la tecnica de sputtering con magnetron desbalanceado con tres grados de desbalanceo diferentes para estudiar la influencia de este parametro en las propiedades electricas. Se crecieron multicapas con un espesor total de aproximadamente 1 microm y un periodo de bicapa (A) de 200 nm, 100 nm y 20 nm. Las multicapas se produjeron a temperatura ambiente sobre acero H13 y silicio (100) y se estudio su microestructura y las propiedades electricas en funcion del campo magnetico. La formacion de fases se caracterizo a traves de Difraccion de Rayos X y los resultados muestran las orientaciones (111) y (200) para todas las multicapas. Se obtuvieron imagenes de la seccion transversal a traves de Microscopia Electronica de Barrido y los resultados muestran la formacion de una estructura en multicapas.
ELECTRICAL FURNACE FOR PRODUCING CARBIDE COATINGS USING THE THERMOREACTIVE DEPOSITION/DIFFUSION TECHNIQUE
CASTILLEJO,FABIO; MARULANDA,DIANA; RODRIGUEZ,OLIVO; OLAYA,JHON;
DYNA , 2011,
Abstract: in this work, the design of an electrical furnace for producing transition metal-based hard coatings using the thermo-reactive deposition and diffusion (trd) technique is described. performance of the system was tested through production of vanadium carbide (vc) and niobium carbide (nbc) coatings on steel aisi d2. x-ray diffraction (xrd) and optical microscopy techniques were used to study phase formation and microstructure, respectively. hardness was determined by using knoop microhardness measurements. xrd results showed the presence of vc and nbc, and as meb results clearly show, the formation of regular thickness coatings. the results obtained allow for assessing that the designed and built furnace fulfills the requirements of the trd technique for obtaining different types of hard coatings.
ELECTRICAL FURNACE FOR PRODUCING CARBIDE COATINGS USING THE THERMOREACTIVE DEPOSITION/DIFFUSION TECHNIQUE
FABIO CASTILLEJO,DIANA MARULANDA,OLIVO RODRIGUEZ,JHON OLAYA
DYNA , 2011,
Abstract: In this work, the design of an electrical furnace for producing transition metal-based hard coatings using the thermo-reactive deposition and diffusion (TRD) technique is described. Performance of the system was tested through production of vanadium carbide (VC) and niobium carbide (NbC) coatings on steel AISI D2. X-ray diffraction (XRD) and optical microscopy techniques were used to study phase formation and microstructure, respectively. Hardness was determined by using Knoop microhardness measurements. XRD results showed the presence of VC and NbC, and as MEB results clearly show, the formation of regular thickness coatings. The results obtained allow for assessing that the designed and built furnace fulfills the requirements of the TRD technique for obtaining different types of hard coatings.
Evaluación de la resistencia a la corrosión de multicapas de Cr/ CrN depositadas con UBM
Chipatecua Godoy,Yuri Lizbeth; Marulanda Cardona,Diana Maritza; Olaya Flórez,Jhon Jairo;
Ingeniería e Investigación , 2011,
Abstract: this work was aimed at evaluating the corrosion resistance of multilayer cr/crn coatings deposited by the unbalanced magnetron sputtering (ubm) technique. coatings were produced at room temperature using 400 ma discharge current, 9 sccm argon flow and 3 sccm nitrogen flow. the total thickness of coatings deposited on aisi 304 stainless steel and silicon (100) varied between 0.2 a 3 μm as bilayer period varied between 20 and 200 nm. coating microstructure and chemical composition was studied through scanning electron microscopy (sem) and texture and crystalline phases were analysed by x-ray diffraction (xrd) before and after corrosion tests which were carried out by potentiodynamic polarisation using 0.5 m h2so4 + 0.05m kscn s
Estudio comparativo de la evaluación a la corrosión de recubrimientos de crn y crn/cr con recubrimientos de cromo electrodepositado y pinturas tipo epoxy
Torres,Magda; Chipatecua,Yuri; Marulanda Cardona,Diana Maritza; Olaya Florez,Jhon Jairo;
Ingeniería e Investigación , 2010,
Abstract: this work was aimed at comparing the corrosion resistance of crn and crn/cr coatings deposited through unbalanced magnetron sputtering (ubm), cr industrial coatings and epoxy paints. ubm coatings were optimised and produced at room temperature, using 400 ma discharge current. ar and n2 flow rates were set at 9 standard cubic centimetres per minute(sccm) and 3 sccm, respectively. deposition times were set to produce crn monolayers and nanometric multilayers having 1 μm total thickness and 100 nm period. coating microstructure was determined through scanning electron microscopy as texture and crystalline phases were determined using x-ray diffraction and infrared spectroscopy. corrosion resistance was studied with anodic polarisation tests using 0.5m h2so4 and 0.05m kscn solution. nanometric multilayers improved stainless steel corrosion resistance and it was observed that coated crn steel a36 could be an alternative for replacing stainless steel in acid environments. corrosion mechanisms for the coatings so deposited are discussed.
OBTENCIóN DE OLEORRESINA DE PIMENTóN (Capsicum annuum L.) EXTRACTION OF OLEORESIN FROM SWEET PEPPER (Capsicum annuum L.)
Jhon A CARDONA. R.,Guillermo L. LOPERA M.,Alejandra M. MONTOYA R.,Ana M. MONTOYA V.
Vitae , 2006,
Abstract: La oleorresina de pimentón (Capsicum annuum L.), la cual contiene fundamentalmente carotenoides, capsaicinoides y algunas vitaminas, tradicionalmente se usa en la industria alimentaria. ésta se obtiene mediante un proceso con las siguientes etapas: a) escaldado, b) troceado, c) secado, d) molienda, y e) extracción con solventes volátiles (hexano, acetona, acetato de etilo). Los pigmentos que se extraen se analizan mediante HPLC en fase reversa y se comparan con la oleorresina de paprika comercial importada por la empresa TECNAS . El rendimiento que se obtiene en el laboratorio está entre el 3 y 6%. Los resultados muestran la importancia del escaldado y del secado: el escaldado permite alcanzar una humedad del 13,56% en 320 min (sin escaldar en el mismo tiempo se llega al 21,01%) y el secado posibilita la extracción con solventes. Oleoresin from sweet pepper (Capsicum annuum L.), which contains mainly carotenoids, capsaicinoids and some vitamins, has been currently used in the food industry. and is obtained with the following procedure: a) scalding, b) chopping, c) drying, d) milling, and e) solvent extraction (hexane, acetone, ethyl acetate). Extracted pigments are analyzed using reverse phase HPLC and the results are compared with the oleoresin obtained from comercial paprika imported by TECNAS . The yield achieved in the laboratory is 3-6%. The results show that scalding and drying are important: the scalding allows to reach an humidity of 13.56% in 320 min (without scalding the humidity reached is 21.01%) and the drying allows extraction with solvents.
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