Papers by Gerardo Rodriguez
Skin disorders affect millions of people all over the world. There are limited options to treat d... more Skin disorders affect millions of people all over the world. There are limited options to treat dermal illnesses such as vitiligo, psoriasis, and atopic dermatitis (eczema). Central American ferns are a potential source of bioactive metabolites against those diseases. Currently, Polypodium leucotomos Poir. (Phlebodium aureum (L.) J. Sm. synonym) is the only one being commercially utilized for this purpose. In this work, we evaluated the concentration of the skin bioactive compounds: quinic and chlorogenic acid, in the extract of 20 wild ferns from Costa Rica. We also evaluated the antimicrobial capabilities of the raw extracts of wild ferns and the sun protection factor (SPF) of the extracts. We found 19 out of 20 have either an important concentration of the compounds mentioned above or antimicrobial properties. Also, most samples result in higher SPF than P. aureum’s rhizome. We also have studied the fern acclimatization, at different shading conditions, finding a significant infl...
Ingeniería e Investigación
Las matemáticas han estado incluidas en los pensums de ingeniería química desde sus comienzos ini... more Las matemáticas han estado incluidas en los pensums de ingeniería química desde sus comienzos inicialmente como un aspecto formativo, en la aplicación de la lógica deductiva y su carácter formal, y posteriormente como una herramienta para el diseño, el análisis y optimización de procesos químicos. El modelo matemático trajo una mayor relación entre las dos disciplinas, pues la solución de los modelos requirió de técnicas más exactas y rápidas. Numerosos libros sobre matemáticas aplicadas han sido escritos por ingenieros químicos especializados en matemáticas o matemáticos con especialidad en Ingeniería Química, lo cual demuestra la dualidad que debe darse en la enseñanza de esta asignatura.
Revista Ingenieria E Investigacion, 2006
Downstream separation processes in biotechnology form part of the stages having most impact on a ... more Downstream separation processes in biotechnology form part of the stages having most impact on a product's final cost. The tendency throughout the world today is to replace fossil fuels with those having a renewable origin such as ethanol; this, in turn, produces a demand for the same and the need for optimising fermentation, treating vinazas and dehydration processes. The present work approaches the problem of dehydration through simulating azeotropic ethanol extractive distillation using glycerol as separation agent. Simulations were done on an Aspen Plus process simulator (Aspen Tech version 11.1). The simulated process involves two distillation columns, a dehydrator and a glycerol recuperation column. Simulation restrictions were ethanol's molar composition in dehydrator column distillate and the process's energy consumption. The effect of molar reflux ratio, solvent-feed ratio, solvent entry and feed stage and solvent entry temperature were evaluated on the chosen restrictions. The results showed that the ethanol-water mixture dehydration with glycerol as separation agent is efficient from the energy point of view.
Innotec, Jan 10, 2013
Nuestro trabajo utiliza quitosano aislado de líneas de desecho de la producción de camarón nativa... more Nuestro trabajo utiliza quitosano aislado de líneas de desecho de la producción de camarón nativas y colágeno aislado de desechos de la piel de tilapia de cultivo; con estos biopolímeros se sintetizaron materiales compuestos a partir de la mezcla de quitosano y colágeno (80:20 v/v). Los compositos de colágeno-quitosano fueron formulados como andamiajes en 3D similares a una esponja, aplicando tecnologías previamente desarrolladas en nuestro grupo de investigación basadas en evaporación de solvente mediante liofilización. Los andamiajes de colágeno-quitosano fueron caracterizados de acuerdo con sus propiedades térmicas (análisis termogravimétrico) y morfología (microscopía de barrido electrónico). Finalmente, se estudió el efecto de la adición de un agente porógeno en las propiedades de absorción de agua y la morfología de los andamiajes tridimensionales. Palabras clave: Quitosano, colágeno, andamiajes 3D, ingeniería de tejidos.
Ingeniería e Investigación, 1996
La selección de un sistema de tratamiento de residuos debe seguir los criterios del proceso denom... more La selección de un sistema de tratamiento de residuos debe seguir los criterios del proceso denominado BATEA (Mejor Proceso Disponible y Factible Técnica y económicamente). Debido a que su aplicación es difícil por no contar con parámetros objetivos de evaluación, se presenta un método que clasifica los criterios de evaluación en generales y específicos. Para la cuantificación de estos aspectos se emplean factores de ponderación como FQO, FCI, FTR, FD y el Factor de Aplicabilidad del Tratamiento (FAT). El método aplicado a la vinaza permite concluir que es la evaporación el mejor sistema de tratamiento para dicho proceso, mientras no se desarrollen otros sistemas o se aumente la tasa retributiva.
SIGNUM - Revista da ABREM, 2014
A lo largo de la Edad Media castellana pueden encontrarse variadas formas de vinculación entre la... more A lo largo de la Edad Media castellana pueden encontrarse variadas formas de vinculación entre la Corona, la Iglesia y el territorio, que dieron por resultado diferentes instituciones de articulación territorial, muchas de ellas vinculadas con el fenómeno fronterizo o bien la aplicación de políticas específicas relacionadas con la imposición de una determinada ortodoxia cristiana como en políticas concretas de control de las instituciones y cuestiones religiosas. Estos procesos de larga duración terminaron dando rasgos de identidad a la Corona de Castilla de los siglos XIV a XVI, en especial las fronteras, los milagros y la confesionalización.
Uniciencia, Jun 30, 2013
Recibido el 30 de junio de 2012. Corregido el 28 de agosto de 2012. Aceptado el 28 de octubre de ... more Recibido el 30 de junio de 2012. Corregido el 28 de agosto de 2012. Aceptado el 28 de octubre de 2012. RESUMEN: El propósito del presente trabajo fue en primera instancia el realizar un estudio del contenido de filantósidos y lignanos presentes en muestras de diferentes partes del árbol de chilillo (Phyllantus acuminatus Vahl), colectadas en diferentes sitios del país. Para la primera parte del estudio se utilizó cromatografía de alta eficiencia (HPLC). Los resultados de estas pruebas mostraron no solo variación en el número de picos del cromatograma, sino también variaciones en la intensidad, en función del sitio de colecta de las muestras. Por otra parte, se desarrollo un método espectrofotométrico simple, rápido y barato para cuantificar el contenido de filantósidos y lignanos que fuera comparable con el método por HPLC. Los resultados obtenidos con el nuevo método se correlacionaron con los datos obtenidos empleando la técnica de HPLC. El coeficiente de determinación obtenido en esta correlación fue excelente y estadísticamente significativo (R 2 = 0,99; p < 0,05). Finalmente se evaluó la actividad antioxidante con el ensayo del radical libre 2,2-difenil-1-picrilhidrazil (DPPH) y se determinó el contenido de polifenoles totales, mediante el método Folin-Ciocalteu. Tradicionalmente existe una excelente correlación entre el contenido de polifenoles totales y la actividad antioxidante; sin embargo, en este estudio no fue posible obtenerla, ya que la correlación entre ambos métodos resultó ser relativamente baja (R 2 = 0,4334). Estos resultados revelan claramente que el árbol de chilillo no es una fuente potencial de polifenoles y no posee una buena capacidad antioxidante, especialmente si se compara con otras muestras vegetales ricas en compuestos
Revista Puertorriquena De Psicologia, 2006
T his article briefly relates the history of Carlos Albizu University (CAU) and its campuses in S... more T his article briefly relates the history of Carlos Albizu University (CAU) and its campuses in San Juan, Puerto Rico and Miami, Florida, since the University's foundation in 1966. It describes the progressive development of the institution throughout the 40 years since its foundation, starting with the Masters Program in Clinical Psychology and following the programmatic growth to other Masters specialties, doctoral degree programs and undergraduate programs. This recount describes how the University's academic excellence has complemented its need to become an activist to effect changes in public policies that harm the vulnerable groups in our society. CAU also have created innovative programs in collaboration with government agencies like Family Department and the Correctional Department. Finally, this article exposes CAU's academic commitment to the science of learning through the creation of the Scientific Investigation Institute, as well as the University's commitment to the wellbeing of underrepresented sectors of the community through the services offered at the Community Mental Health Clinics housed at both campuses
The purpose of this research work was in the first instance, to conduct a study of the content of... more The purpose of this research work was in the first instance, to conduct a study of the content of phyllantosides and lignans in samples from different parts of the tree known as “Chilillo” (Phyllanthus acuminatus Vahl), collected at different sites of the country. The first objective of the study was focused on the characterization of the samples using high efficiency liquid chromatography (HPLC). The results obtained by this technique showed variation not only in the number of peaks in each chromatogram, but also in the peak intensity, also significant variations in the composition of the samples were found among the different collecting sites. The second objective of this work, was to develop a simple, fast and inexpensive colorimetric method to quantify the content of phyllantosides and lignans in different samples of Chilillo that was comparable to the HPLC data. The results obtained with the new method were correlated with the results obtained by HPLC, the coefficient of determination obtained in this correlation was excellent and statistically significant (R2 = 0,99; p < 0,05). Finally, the last objective of the study was to evaluate the antioxidant activity in all the samples of Chilillo and its correlation with its total polyphenolic content, using the free radical 2,2-diphenyl-1-picrylhydrazyl (DPPH) for antioxidant activity determinations and Folin-Ciocalteu for total polyphenolic content. Traditionally there is a good correlation between total polyphenol content and antioxidant activity, but in this study the correlation between the two methods was relatively low (R2 = 0.4334). These results clearly show that Chilillo tree can not be consider as an important source of polyphenols or natural antioxidants, especially when compared with other plant samples rich in phenolic compounds such as blackberry (Rubus sp) or rambutan (Nephelium lappaceum).
The Journal of Nutrition, 2010
4 on behalf of the HELENA study group 16
Industrial & Engineering Chemistry Research, 2013
ABSTRACT Liquid-phase esterification of propionic acid with isoamyl alcohol using Amberlyst 70 io... more ABSTRACT Liquid-phase esterification of propionic acid with isoamyl alcohol using Amberlyst 70 ion exchange resin as catalyst was studied. Batch isothermal experiments were performed at different acid to alcohol molar ratios (1:2, 1:1, and 2:1), reaction temperatures (353.15, 373.15, and 393.15 K), and catalyst loadings (8.0, 4.0, and 0.8 wt % of (kg of cat)·(kg of soln)−1). Kinetic data were regressed with pseudohomogeneous and heterogeneous reaction models based upon mole fractions and nonrandom two-liquid (NRTL) computed activities. Obtained models accurately fit esterification kinetics and can be used in simulation of reaction and reactive distillation processes to produce isoamyl propionate.
Ferroelectrics, 1984
... Following the procedures used by F. Karal and J. Keller&amp;amp;amp;#x27;&amp;amp;amp... more ... Following the procedures used by F. Karal and J. Keller&amp;amp;amp;#x27;&amp;amp;amp;#x27; a plane wave solution is then assumed for the macroscopic field in the equation resulting from the FSA and the effective dielectric constant corrected for multiple scattering effect is then obtained. ...
European Journal of Clinical Nutrition, 2005
Objective: To compare the most commonly used equations to predict body fatness from skinfold thic... more Objective: To compare the most commonly used equations to predict body fatness from skinfold thickness, in male and female adolescents, with dual-energy X-ray absorptiometry (DXA) as a reference method of fatness measurement. Design: Cross-sectional nutrition survey. Setting: General adolescent population from Zaragoza (Spain). Subjects and methods: A total of 238 Caucasian adolescents (167 females and 113 males), aged 13.0-17.9 y, were recruited from 15 school groups in 11 public and private schools. The percentage fat mass (%FM) was calculated by using skinfoldthickness equations. Predicted %FM was compared with the reference %FM values, measured by DXA. The lack of agreement between methods was assessed by calculating the bias and its 95% limits of agreement. Results: Most equations did not demonstrate good agreement compared with DXA. However, in male adolescents, Slaughter et al equations showed relative biases that were not dependent on body fatness and the limits of agreement were narrower than those obtained from the rest of equations. In females, Brook's equation showed nonsignificant differences against DXA and the narrowest 95% limits of agreement. Only biases from Brook and Slaughter et al equations were not dependent on body fatness in female adolescents. Conclusions: Accuracy of most of the skinfold-thickness equations for assessment of %FM in adolescents was poor at the individual level. Nevertheless, to predict %FM when a relative index of fatness is required in field or clinical studies, Slaughter et al equations may be used in adolescents from both sexes and the Brook equation in female adolescents.
Digestive Diseases, 2003
Parasitic infections are highly prevalent in the general population. A relation between a parasit... more Parasitic infections are highly prevalent in the general population. A relation between a parasitic infection and absorption of minerals is not an easy task. Serum levels of copper, zinc and magnesium were prospectively measured in 64 children with intestinal parasitic infection. Thirty-nine children with Enterobius vermicularis were treated with pyrantel pamoate and 25 children with Giardia lamblia with tinidazole and metronidazole. Three months after treatment, significant differences in serum copper, zinc and magnesium were seen in patients with E. vermicularis infection, and in serum magnesium levels in patients with G. lamblia. Although the pathogenic mechanism is not clear, these findings could reflect a deficiency related to malabsorption due to mucous affection. Early detection and treatment of intestinal parasitosis could avoid these serum mineral deficiencies.
2009 AIChE Annual …, 2009
The optimal design of an extractive distillation system is developed for the separation of the et... more The optimal design of an extractive distillation system is developed for the separation of the ethanol-water azeotropic mixture using ethylene-glycol as entrainer. The research in this field has been motivated by the growing demand of anhydrous ethanol as motor fuel and ...
Acta Paediatrica, 2007
To identify the best anthropometric predictor of the metabolic syndrome in children. Screening pe... more To identify the best anthropometric predictor of the metabolic syndrome in children. Screening performance was evaluated in a clinical setting. The study included 140 children: 72 non-obese and 68 with non-syndromal obesity. Body mass index (BMI), waist circumference and triceps/subscapular skinfolds ratio were used as predictor variables, and systolic blood pressure, diastolic blood pressure, glucose, uric acid, fasting insulin, triglycerides and HDL-C as metabolic syndrome variables. The areas under the receiver operating characteristic (ROC) curves were 0.849 (95% CI: 0.780, 0.919) for BMI, 0.868 (95% CI: 0.801,0.934) for waist circumference and 0.834 (95% CI: 0.757,0.910) for the triceps/subscapular skinfolds ratio. No statistically significant differences were found for the three areas under the ROC curves. The point on the ROC curve closest to 1 corresponded to the 65th percentile for BMI, to the 70th percentile for waist, and to the 40th percentile for the triceps/subscapular skinfolds ratio. Waist circumference seems to be the best predictor of children with the metabolic syndrome in paediatric clinical settings.
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Papers by Gerardo Rodriguez