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Search Results: 1 - 10 of 51883 matches for " Luis Fernando Peralta Berrospi "
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Actividad antibacteriana de Pelargonium peltatum (L.) L'Hér. sobre Streptococcus mutans, Streptococcus sanguis y Streptococcus mitis frente a clorhexidina Antibacterial activity of Pelargonium peltatum (L.) L'Her. against Streptococcus mutans, Streptococcus sanguis and Streptococcus mitis versus chlorhexidine
Juana del Carmen Guerrero Hurtado,Zoila Mercedes Ortiz Rubio,Luis Fernando Peralta Berrospi,Fredy Romel Pérez Azahuanche
Revista Cubana de Plantas Medicinales , 2013,
Abstract: Introducción: Pelargonium peltatum (L.) L'Hér (geranio hiedra) es ampliamente utilizado en medicina natural para el tratamiento de enfermedades bucales, pero se desconocen aún sus propiedades farmacológicas, actividad antibacteriana y la composición de sus fitoconstituyentes. Objetivo: realizar un estudio comparativo de la actividad antibacteriana in vitro del extracto acuoso obtenido de las hojas de Pelargonium peltatum (L.) L'Hér (geranio hiedra) sobre Streptococcus mutans, Streptococcus sanguis y Streptococcus mitis, frente a la clorhexidina. Métodos: para el ensayo antibacteriano se empleó el método de difusión en agar. Se trabajó con 18 muestras de microorganismos de cada especie mencionada, aisladas de los pacientes de una clínica dental. Posteriormente, se prepararon 6 concentraciones diferentes del extracto acuoso, para comparar la actividad antibacteriana frente al colutorio de clorhexidina. El análisis fitoquímico preliminar se realizó mediante el ensayo a la gota. Los datos obtenidos se sometieron a análisis estadísticos como estimadores de media y dispersión, análisis de varianza unifactorial y prueba de Tukey. Resultados: la más alta actividad antibacteriana se obtuvo en la concentración de 400 mg/mL y la más baja en la de 25 mg/mL del extracto acuoso, sobre las tres especies de Streptococcus, en comparación con la clorhexidina; con efecto similar a la concentración de 200 mg/mL. El ensayo fitoquímico preliminar indicó la presencia de flavonoides, taninos, esteroides, antocianinas y saponinas. Conclusiones: el extracto acuoso de Pelargonium peltatum tiene actividad antibacteriana sobre Streptococcus mutans, Streptococcus mitis y Streptococcus sanguis. Introduction: Pelargonium peltatum (L.) L'Her (ivy geranium) is widely used in natural medicine for the treatment of oral disease, but its pharmacological properties, antibacterial activity and phytoconstituent composition are still unknown. Objective: carry out a comparative study of the in vitro antibacterial activity of the aqueous extract obtained from leaves of Pelargonium peltatum (L.) L'Her (ivy geranium) against Streptococcus mutans, Streptococcus sanguis and Streptococcus mitis versus chlorhexidine. Methods: the agar diffusion method was used for the antibacterial assay. A study was conducted of 18 samples of microorganisms from the above-mentioned species, isolated from patients cared for at a dental clinic. Six different concentrations were prepared of the aqueous extract to compare antibacterial activity versus the chlorhexidine gargle. Preliminary phytochemical analysis was conduc
Análisis de estabilidad del reactor PFTR para una reacción con cinética de primer orden utilizando la funcional de Lyapunov
Durán Peralta,Héctor Armando; Córdoba C.,Luis Fernando;
Ingeniería e Investigación , 2007,
Abstract: the stability of reactors having encompassing concentration and temperature parameters, such as continuous flow stirred tank reactors (cstr), has been widely explored in the literature; however, there are few papers about the stability of tubular reactor having distributed spatial concentration and temperature parameters such as the plow flow tubular reactor (pftr). this paper analyses the stability of isothermal and non-isothermal pftr reactors using the lyapunov functional method. the first order kinetic reaction was selected because one of this paper?s objectives was to apply lyapunov functionals to stability analysis of distributed parameter reactors (technique used in electrical engineering systems? stability analysis). the stability analysis revealed asymptotically stable temperature and concentration profiles for isothermal pftr, non-isothermal pftr with kinetic constant independent of temperature and adiabatic non-isothermal pftr. analysis revealed an asymptotically stability region for the heat exchange reactor and an uncertain region where it may have oscillations.
Análisis de estabilidad del reactor PFTR para una reacción con cinética de primer orden utilizando la funcional de Lyapunov Stability analysis of a PFTR reactor for a first order kinetic reaction using the Lyapunov functionals
Durán Peralta Héctor Armando,Córdoba C Luis Fernando
Ingeniería e Investigación , 2007,
Abstract: Abunda la literatura referente al análisis de estabilidad de reactores con parámetros globalizados de concentración y temperatura (por ejemplo el CSTR), en cambio es escasa la literatura sobre la estabilidad de reactores con parámetros distribuidos donde existe distribución espacial de concentración y temperatura, como es el caso del reactor tubular PFTR. Este documento analiza la estabilidad del reactor PFTR isotérmico y no isotérmico para una reacción con cinética de primer orden utilizando la funcional de Lyapunov. Se trabaja con una cinética de primer orden pues un objetivo de este artículo es mostrar cómo se aplica la funcional de Lyapunov al análisis de un reactor de parámetros distribuidos, dado que es casi inexistente la literatura sobre el método de la funcional de Lyapunov aplicada a la estabilidad de reactores (técnica usada en el análisis de estabilidad de sistemas en ingeniería eléctrica). El análisis de estabilidad dio como resultado perfiles de temperatura y concentración asintóticamente estables para los casos PFTR isotérmico, no isotérmico con constante cinética independiente de la temperatura y PFTR no isotérmico adiabático. Para el PFTR con retiro de calor el análisis condujo a una región de estabilidad asintótica y a una región incierta donde puede o no haber oscilaciones. The stability of reactors having encompassing concentration and temperature parameters, such as continuous flow stirred tank reactors (CSTR), has been widely explored in the literature; however, there are few papers about the stability of tubular reactor having distributed spatial concentration and temperature parameters such as the plow flow tubular reactor (PFTR). This paper analyses the stability of isothermal and non-isothermal PFTR reactors using the Lyapunov functional method. The first order kinetic reaction was selected because one of this paper’s oblectives was to apply Lyapunov functionals to stability analysis of distributed parameter reactors (technique used in electrical engineering systems’ stability analysis). The stability analysis revealed asymptotically stable tempe- rature and concentration profiles for isothermal PFTR, non-isothermal PFTR with kinetic constant independent of temperature and adiabatic non-isothermal PFTR. Analysis revealed an asymptotically stability region for the heat exchange reactor and an uncertain region where it may have oscillations.
Avifauna del Estero de Punta Banda, Baja California, México
JIMéNEZ PéREZ, Luis C.;CUEVA, Horacio de la;MOLINA-PERALTA, Fernando;ESTRADA-RAMíREZ, Arnulfo;
Acta zoológica mexicana , 2009,
Abstract: twenty four bird identification and counting campaigns were carried out at estero de punta banda, baja california, mexico between march 2004 and march 2005, in six representative environmental units. thirty-five bird families were registered, including 104 species. sixty-four species were associated with aquatic environments. both, aquatic and terrestrial communities showed clear temporal patterns with three groups associated with seasonal changes. twelve of these species are listed as protected in the mexican environmental legislation. we found evidences of the reproductive success of the clapper rail and the black-necked stilt populations in disturbed areas. these results indicated that the estero de punta banda remains an important reproduction-feeding area for many resident and migratory birds. however, the rapid urban development of the city of ensenada, water pollution, and illegal use of its natural resources, threaten the survival of estero punta banda and its bird species.
AVIFAUNA DEL ESTERO DE PUNTA BANDA, BAJA CALIFORNIA, MéXICO
Luis C. JIMéNEZ PéREZ,Horacio de la CUEVA,Fernando MOLINA-PERALTA,Arnulfo ESTRADA-RAMíREZ
Acta zoológica mexicana , 2009,
Abstract: Entre marzo de 2004 y marzo de 2005 se realizaron veinticuatro salidas de campo quincenales de avistamiento y registro de aves costeras en 6 unidades ambientales del Estero de Punta Banda, Baja California, México. Se registraron 35 familias y 104 especies; 64 estuvieron asociadas al ambiente acuático. La estructura de las comunidades de aves acuáticas y terrestres presentó una secuencia temporal que se caracterizó por la formación de dos grupos asociados con las condiciones de invierno o verano y otro más peque o formado por los censos efectuados en la transición entre ambas estaciones. Doce especies aparecen enlistadas en alguna categoría de protección en la Norma Oficial Mexicana. Se registró el éxito reproductivo de dos especies residentes (Rallus longirostris e Himantopus mexicanus) en áreas disturbadas por estructuras costeras hechas por el hombre. Los resultados indican que el Estero de Punta Banda es importante como área de reproducción, alimentación y descanso de muchas especies de aves residentes y migratorias. Sin embargo, el acelerado crecimiento urbano de la ciudad de Ensenada, la contaminación y el uso desordenado de sus recursos amenaza su presencia y supervivencia.
Teachers's competence and confidence regarding the use of ICT
Helena Peralta,Fernando Costa
Sísifo : Educational Sciences Journal , 2007,
Abstract: The aim of this paper is to present a qualitative multiple case study research on primary school teachers’ competence and confidence level regarding the use of ICT in the teaching and learning practice carried out in five different European countries (Greece, Italy, Portugal, Spain and The Netherlands). Focus group interview was the central data collection technique used in this study. As a result of the data analysis some important issues emerged which gave rise to four main dimensions - individual factors, contextual factors (at macro and micro levels) and factors related with teacher training and education. These factors may function as anchor-points (main categories) for the elaboration of the instruments for further research.
Not so strangers. Patricia Highsmith according to Alfred Hitchcock
Peralta, Jorge Luis
452o F : Revista de Teoría de la Literatura y Literatura Comparada , 2010,
Abstract: In this work I propose to analyze how the cinematographic transposition of Strangers on a train has changed the suffocating amoral world of Patricia Highsmith in a typical Hitchcockian frantic suspense story, blurring the darkest edges of the characters and situations of the original novel. The aim is not to determine whether the film is more , better or worse than the text –an unproductive enterprise– but to reflect on the operations made by the director to seize the literary work and make of it a film that responds to his own vision of the world and of cinema.
AlfaMC: a fast alpha particle transport Monte Carlo code
Luis Peralta,Alina Louro
Physics , 2012,
Abstract: AlfaMC is a Monte Carlo simulation code for the transport of alpha particles. The code is based on the Continuous Slowing Down Approximation and uses the NIST/ASTAR stopping-power database. The code uses a powerful geometrical package allowing the coding of complex geometries. A flexible histogramming package is used which greatly easies the scoring of results. The code is tailored for microdosimetric applications where speed is a key factor. Comparison with the SRIM code is made for transmitted energy in thin layers and range for air, mylar, aluminum and gold. The general agreement between the two codes is good for beam energies between 1 and 12 MeV. The code is open-source and released under the General Public Licence.
Matéria seca, digestibilidade in vitro e composi??o químico-bromatológica do capim (Paspalum notatum ) cv. 'tifton 9' com diferentes idades
Vendramini, Jo?o Maurício Bueno;Haddad, Cláudio Maluf;Castro, Flávio Geraldo Ferreira;Vieira, Andrea Campmany;Heisecke, Osvaldo Ruben Peralta;Tamassia, Luis Fernando Monteiro;
Scientia Agricola , 1999, DOI: 10.1590/S0103-90161999000300018
Abstract: the objective of this research was to evaluate dry matter yield, in vitro digestibility, fiber protein and mineral composition of bahiagrass (paspalum notatum) `tifton 9' clipped at six regrowth stages (20, 27, 34, 41, 48 and 55 days after staging). the experimental design consisted of randomized complete blocks with six trataments (ages) and four replications. dry matter yield ranged from 188 to 593 g m-2, with the cubic regression having the best fit (p< 0.05). concentration of acid detergent fiber, lignin, and crude protein decreased linearly (p<0.01), (p<0.10), (p<0.05) respectively from 387.73 to 370.04, 37.56 to 26.67, 121.33 to 68.88 g kg-1, as well as phosphorus concentration that attained, 1.92 g kg-1 55 days. neutral detergent fiber concentration, in vitro digestibility at potassium, calcium, magnesium and sulphur were not affected (p>0.05) by regrowth age. among the micronutrients, concentration of iron and manganese remained unchanged (p>0.05) during the period, whereas copper levels declined linearly and zinc levels decreased quadratically (p<0.01). dry matter yield, digestibility and concentration of fiber components and minerals presented values similar to other tropical forages, wereas crude protein remained above 70 g kg-1, only up to the 48th day, according to the regression model.
Evaluation of Contact Pressure in Bending under Tension Test by a Pressure Sensitive Film  [PDF]
Luis Fernando Folle, Lirio Schaeffer
Journal of Surface Engineered Materials and Advanced Technology (JSEMAT) , 2016, DOI: 10.4236/jsemat.2016.64018
Abstract: The contact pressure acting on the sheet/tools interface has been studied because of growing the concern about the wear of tools. Recent studies make use of numerical simulation software to evaluate and correlate this pressure with the friction and wear generated. Since there are many studies that determine the coefficient of friction in sheet metal forming by bending under tension (BUT) test, the contact pressure between the pin and the sheet was measured using a film that has the ability to record the applied pressure. The vertical force applied to pin was also measured. The results indicate that the vertical force is more accurate to set the contact pressure that using equations predetermined. It was also observed that the contact area between the sheet and the pin is always smaller than the area calculated geometrically. The friction coefficient was determined for the BUT test through several equations proposed by various authors in order to check if there is much variation between the results. It was observed that the friction coefficient showed little variation for each equation, and each one can be used. The material used was the commercially pure aluminum, alloy Al1100.
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