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Search Results: 1 - 10 of 249677 matches for " Luis G. Guerrero-Ramírez "
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New Family of Functionalized Monomers Based on Amines: A Novel Synthesis that Exploits the Nucleophilic Substitution Reaction  [PDF]
Lissette Agüero, Luis G. Guerrero-Ramírez, Issa Katime
Materials Sciences and Applications (MSA) , 2010, DOI: 10.4236/msa.2010.13018
Abstract: Chemistry modifications are usually performed to introduce specific group that can increase properties and functionality of materials. In this study, we present the synthesis of six new functionalized monomers prepared by nucleophilic substitution reactions. Reaction of aliphatic and aromatic amines with acryloyl chloride at –20ºC, in presence of triethylamine allowed the synthesis of the corresponding amides. Proton nuclear magnetic resonance (1H NMR) spectroscopy, Fourier-transform infrared (FTIR) spectroscopy and ultraviolet- visible (UV-Vis) measurements confirmed the success of the synthesis with a yield over 90%. These compounds emerged as potentially attractive monomers since they can be used to obtain stimuli-sensitive polymeric materials, due to the presence of amide and pyridine groups.
Maximización del índice vida útil/volumen de los filtros usados en accionadores de máquinas eléctricas
Calleja-Gjumlich, J.H.;Guerrero-Ramírez, G.V;Jiménez-Grajales, H.R.;
Ingeniería, investigación y tecnología , 2011,
Abstract: reliability is a main issue in standard adjustable-speed drives. the electrolytic capacitor, part of the low-pass filter in the dc-link, has been blamed as a failure-prone component, and several approaches have been followed to improve the reliability. a popular strategy to improve the operational life consists in derating the capacitor, to higher nominal voltages. the drawback of the approach, however, is that it produces larger apparatuses. in this paper, the ratio "operational life/ volume" is proposed as an index to evaluate a particular design. the index can be maximized following a methodology based on the design of experiments technique. an example developed for a 5 kw motor drive shows that the index can be improved by designing the filter at lower cut-off frequencies.
Maximizing the Operational Life/Volume Index in Filters Used in Adjustable Speed Drives
Calleja-Gjumlich J.H.,Guerrero-Ramírez G.V.,Jiménez-Grajales H.R.
Ingeniería, investigación y tecnología , 2011,
Abstract: Reliability is a main issue in standard adjustable-speed drives. The electrolytic capacitor, part of the low-pass fi lter in the DC-link, has been blamed as a ailureprone component, and several approaches have been followed to improve the reliability. A popular strategy to improve the operational life consists in derating the capacitor, to higher nominal voltages. The drawback of the approach, however, is that it produces larger apparatuses. In this paper, the ratio “Operational Life/Volume” is proposed as an index to evaluate a particular design. The index can be maximized following a methodology based on the design of experiments technique. An example developed for a 5 kW motor drive shows that the index can be improved by designing the fi lter at lower cut-off frequencies.
Enraizamiento de estacas de semeruco (Malpighia glabra L.)
Rivero Maldonado,G. del C; Guerrero,R; Ramírez,M;
Revista de la Facultad de Agronomía , 2005,
Abstract: it is well known that acerola ripe fruit has the highest acid ascorbic content among all fruit crops. in order to clone promissory genotypes through vegetative dissemination, this study was performed to evaluate the rooting capacity of apical (ac) and sub-apical (sc) cuttings treated with indole butyric acid (iba) at 0, 750, 1500, 3000 and 4500 mg kg-1. these factors were arranged in a completely randomized design, with five cuttings as an experimental unit. each treatment was replicated five times. cuttings were placed in a partially-closed case propagation located in the university nursery of la universidad del zulia. after sixty days, surviving cutting percentage (sc), rooted cutting percentage (rc), root number (rn) and length (rl) were evaluated. results showed significant differences (p<0.01) among treatments for rc, rn and rl the highest rc (48%), rn (0.80 roots cutting-1) and rl (5.64 cm) were obtained using ac and 750 mg kg-1 iba, compared to control (8%; 0.44 roots cutting-1 and 1.74 cm, respectively). it is suggested further evaluation on iba dosage between 500 and 1000 mg kg-1 in order to determine the optimum dosage.
Enraizamiento de estacas de semeruco (Malpighia emarginata Sessé & Moc. ex DC)
Rivero Maldonado,G.; Ramírez,M.; Caraballo,B.; Guerrero,R.;
Revista de la Facultad de Agronomía , 2005,
Abstract: abstract this research was carried out with the purpose of establishing a vegetative propagation methodology to multiply selections of malpighia emarginata. the objectives were: 1) to evaluate the rooting of apical cuttings under the following rooting media: sugarcane rum + organic manure from river bank (s1); worm humus + organic matter from river bank (s2); coconut shell + organic manure from river bank (s3); top soil + organic manure from river bank (s4); and the application or not of indole butyric acid (aib) at 5000 mg kg-1, and 2) to determine the primordial rooting on cuttings treated or non treated with aib. it was used a completely randomized design using five replications treatment-1. the experimental unit was five stakes for the first objective and 10 stakes for the second objective. the following variables were measured 60 days after the treatments of rooting: percentage (%) of alive stakes (pv), percentage (%) of rooting (pe), percentage (%) of primordial root (pp), root number (nr) and root length (lr). microscope observations were done weekly to follow the primordial growth on five stakes. the results showed significant differences between the substrates (p<0.01), s1 induced the best rooting considering pe and lr (47.5 and 5.02 cm, respectively); aib affected pe, nr, and lr when treated with aib were of 37.5%, 1.91 roots stakes-1 and 4.22 cm respectively in comparison with no treatment of aib that were of 23.75%, 0.59 roots cutting-1 and 2.06 cm (p<0.01). the primordium roots were favored by the aib treatment at 5000 mg kg-1, shortening their development in two weeks; a mean of 1.5 primordium roots stakes-1 was obtained. other rooting substrates and levels of aib need to be evaluated for these plant specie.
Enraizamiento de estacas de semeruco (Malpighia glabra L.) Rooting of acerola (Malpighia glabra L.)
G. del C Rivero Maldonado,R Guerrero,M Ramírez
Revista de la Facultad de Agronomía , 2005,
Abstract: La fruta madura del semeruco es reconocida mundialmente como la de más alto contenido de ácido ascórbico, lo cual le confiere a la especie un alto valor hortícola. Con la finalidad de clonar genotipos promisorios a través de la propagación vegetativa se realizó esta investigación, cuyo objetivo fue evaluar la capacidad de enraizamiento de estacas apicales (EA) y subapicales (SA) tratadas con ácido indol butírico (AIB) a concentraciones de 0, 750, 1500, 3000 y 4500 mg kg-1 . Estos factores fueron estudiados en un dise o completamente al azar utilizando cinco repeticiones por tratamiento y cinco estacas como unidad experimental. Las estacas se establecieron en un propagador semi-cerrado ubicado en el Vivero Universitario de la Universidad del Zulia. Después de 60 días de establecido el ensayo se evaluó: porcentaje de estacas vivas (PV), estacas enraizadas (PE), número y longitud de raíces (NR y LR, respectivamente). Se encontraron diferencias significativas (P<0,01) para el efecto de tratamientos en las variables PE, NR y LR. La combinación conformada por EA y 750 mg kg-1 de AIB indujo mayor PE (48%), NR (0,80 raíces estaca-1) y LR (5,64cm) en comparación con el tratamiento testigo (8%, 0,44 raíces estaca-1 y 1,74cm, respectivamente). Se recomienda evaluar estacas subapicales con AIB a concentraciones de 500 a 1000 mg kg-1 a fin de determinar la dosis óptima para la propagación masiva de esta especie. It is well known that acerola ripe fruit has the highest acid ascorbic content among all fruit crops. In order to clone promissory genotypes through vegetative dissemination, this study was performed to evaluate the rooting capacity of apical (AC) and sub-apical (SC) cuttings treated with indole butyric acid (IBA) at 0, 750, 1500, 3000 and 4500 mg kg-1. These factors were arranged in a completely randomized design, with five cuttings as an experimental unit. Each treatment was replicated five times. Cuttings were placed in a partially-closed case propagation located in the University nursery of La Universidad del Zulia. After sixty days, surviving cutting percentage (SC), rooted cutting percentage (RC), root number (RN) and length (RL) were evaluated. Results showed significant differences (P<0.01) among treatments for RC, RN and RL The highest RC (48%), RN (0.80 roots cutting-1) and RL (5.64 cm) were obtained using AC and 750 mg kg-1 IBA, compared to control (8%; 0.44 roots cutting-1 and 1.74 cm, respectively). It is suggested further evaluation on IBA dosage between 500 and 1000 mg kg-1 in order to determine the optimum dosage.
Enraizamiento de estacas de semeruco (Malpighia emarginata Sessé & Moc. ex DC)
G. Rivero Maldonado,M. Ramírez,B. Caraballo,R. Guerrero
Revista de la Facultad de Agronomía , 2005,
Abstract: Con el propósito de establecer una metodología de propagación por estacas destinada a multiplicar fenotipos sobresalientes de semeruco (Malpighia emarginata) se llevó a cabo una investigación que presentó como objetivos: 1) evaluar el efecto del tipo de sustrato: cachaza de ca a de azúcar + abono de río (S1); humus de lombriz + abono de río (S2); concha de coco + abono de río (S3) y capa vegetal + abono de río (S4), y del ácido indolbutírico (AIB) a 5000 mg kg-1 sobre el enraizamiento de estacas apicales y 2) determinar la formación de primordios a través del análisis histológico en estacas tratadas y no tratadas con AIB. Los tratamientos se dispusieron en dise os completamente al azar utilizando cinco repeticiones por tratamiento. La unidad experimental estuvo representada por cinco estacas para el primer objetivo y diez estacas para el segundo. En el enraizamiento se evaluaron las variables: porcentaje de estacas vivas (PV), porcentaje de estacas enraizadas (PE), porcentaje de estacas con primordios (PP), número y longitud de raíces (NR y LR, respectivamente), las cuales fueron evaluadas a los 60 días después de establecido el ensayo. Para la determinación de primordios se realizaron cortes histológicos semanalmente. Los cortes fueron efectuados en cinco estacas por tratamiento, los cuales se examinaron en un microscopio óptico. Con relación a los resultados se demostró que el factor tipo de sustrato afectó PE y LR (P<0,01) obteniéndose los mayores valores en S1 con 47,5 y 5,02 cm, respectivamente. Mientras que la aplicación de AIB promovió PE, NR y LR (37,5%, 1,91 raíces estaca-1 y 4,22 cm, respectivamente) en comparación con el testigo (23,75%, 0,59 raíces estaca-1 y 2,06 cm, respectivamente). En la determinación de primordios radicales se observó que este proceso resultó favorecido con la aplicación de AIB a 5000 mg kg-1 acortando su formación a las dos semanas; se obtuvo un promedio de 1,5 primordios estaca-1 a nivel de la sección de la estaca donde se practicaron los cortes. Como recomendaciones se sugiere la evaluación de otros sustratos, así como otras dosis de AIB. This research was carried out with the purpose of establishing a vegetative propagation methodology to multiply selections of Malpighia emarginata. The objectives were: 1) to evaluate the rooting of apical cuttings under the following rooting media: sugarcane rum + organic manure from river bank (S1); worm humus + organic matter from river bank (S2); coconut shell + organic manure from river bank (S3); top soil + organic manure from river bank (S4); and the application or not of indo
REVISIóN DE ESTáNDARES RELEVANTES Y LITERATURA DE GESTIóN DE RIESGOS Y CONTROLES EN SISTEMAS DE INFORMACIóN
GUERRERO JULIO,MARLENE LUCILA; GóMEZ FLóREZ,LUIS CARLOS;
Estudios Gerenciales , 2011,
Abstract: risk management and controls in information systems (rmcis) are important activities involved with management systems. nevertheless, although organizations seem to have an interest in its application, rmcis has not yet achieved its real impact because there is an inadequate understanding of its meaning or purpose and there is also a lack of organizational change processes needed for its implementation. this article presents a review of the current most relevant rmcis standards for the purpose of proposing an integration of the roles and activities that organizations should carry out, together with an analysis of the risk levels and their implications for information systems.
REVISIóN DE ESTáNDARES RELEVANTES Y LITERATURA DE GESTIóN DE RIESGOS Y CONTROLES EN SISTEMAS DE INFORMACIóN
MARLENE LUCILA GUERRERO JULIO,LUIS CARLOS GóMEZ FLóREZ
Estudios Gerenciales , 2011,
Abstract: La gestión de riesgos y controles en sistemas de información (GRCSI) es una actividad importante en los sistemas de gestión. No obstante, aunque en lasorganizaciones parece haber interés en su aplicación, la GRCSI aún no logra el impacto deseado, debido en gran parte a la falta de entendimiento de su sentido o propósito y a la ausencia de los procesos de cambio organizacional necesarios para su implantación. Este artículo presenta una revisión sobre los estándares de GRCSI más relevantes, con el fin de plantear una propuesta de integración de los roles y las actividades que las organizaciones debendesarrollar, y de analizar los niveles de riesgo y sus implicaciones frente a los sistemas de información.
Bajo peso al nacer y embarazo en la adolescencia en cinco consultorios del médico de la familia
rez Queda,Ramón; Rosabal García,Francisco; Pérez Guerrero,Jorge Luis; Yabor Palomo,Alicia;
Revista Cubana de Medicina General Integral , 1995,
Abstract: a study was performed on 120 pregnant women in an area of 5 medical offices of the family doctor plan from january 1987 to january 1990. of them 56 were under 20 years of age accounting for 46,6 %. a comparative study was carried out between this group and pregnant women over 20 years, and it was observed that teenagers had a greater number of low birth weight infants (88 %) and preterm deliveries. smoking and maternal malnutrition were considered as very important factors in addition to adolescence for low birth weight.
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