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Search Results: 1 - 10 of 27416 matches for " Donaji JIMéNEZ ISLAS "
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Propiedades , aplicaciones y producción de biotensoactivos: una revisión
JIMéNEZ ISLAS, Donaji;MEDINA MORENO, Sergio A.;GRACIDA RODRíGUEZ, Jorge Noel;
Revista internacional de contaminación ambiental , 2010,
Abstract: surfactants are amphiphilic molecules containing both hydrophilic and hydrophobic parts; these substances are located at the fluid-fluid interface with different degrees of polarity from oil-water or air-water interfaces. the properties of surfactants are characterized principally by four parameters: critical micelle concentration (cmc), aggregation number (na), hydrophilic-lipophilic balance (hlb) and cloud point (cp). these parameters are indicative of the potential of the surfactant as an emulsifier and surface-active agent and determine their application, mainly in industry and the environment. surfactants are synthesized chemically or biologically, in which case they are called biosurfactants. although an extensive number of microorganisms are capable of synthesizing biosurfactants, they are mainly produced by bacteria. biosurfactants make up a series of compounds whose structure may be relatively simple such as rhamnolipids, whose structures have mono- and disaccharides joined by glycosidic bonds to hydroxylated carboxylic acids, or more complex such as emulsán, a polymeric biosurfactant with monomeric units of heteropolysaccharides bound to lipids. biosurfactants have advantages over chemical surfactants due to their compatibility with the environment, low toxicity and biodegradability. however, the principal disadvantage is their high production cost in some cases. in this paper the chemical and microbiological properties of surfactants and biosurfactants are described as well as biosurfactant applications, principally in the bioremediation field. the effect of the main process variables on the production of biosurfactants is also discussed, particularly of rhamnolipids from pseudomonas aeruginosa.
PROPIEDADES, APLICACIONES Y PRODUCCIóN DE BIOTENSOACTIVOS
Donaji JIMéNEZ ISLAS,Sergio A. MEDINA MORENO,Jorge Noel GRACIDA RODRíGUEZ
Revista internacional de contaminación ambiental , 2010,
Abstract: Los tensoactivos son moléculas anfifílicas con una porción hidrofílica y otra hidrofóbica; se localizan preferentemente en la interfase de fluidos con diferentes grados de polaridad como son la de aceite-agua o aire-agua. Las propiedades de un tensoactivo son caracterizadas principalmente por cuatro parámetros: concentración micelar crítica (CMC), número de agregación (na), balance hidrofílico-lipofìlico (HLB) y punto de nube (PN). Estos parámetros indican el potencial del tensoactivo como agente emulsificante y de superficie, determinando su aplicación en diversas áreas, principalmente a nivel industrial y ambiental. Los tensoactivos son sintetizados vía química o biológica, denominando a los últimos biotensoactivos. Aunque una amplia gama de microorganismos son capaces de sintetizar biotensoactivos, las bacterias son las principales productoras. Los biotensoactivos integran una serie de compuestos cuya estructura puede ser simple -como los ramnolípidos, formados por mono y disacáridos unidos por enlaces glicosídicos a ácidos grasos hidroxilados-, o compleja, como el emulsán, biotensoactivo polimérico complejo que contiene unidades monoméricas de heteropolisacáridos enlazados a lípidos. Los biotensoactivos muestran ventajas sobre los de síntesis química debido a su compatibilidad con el ambiente, baja toxicidad y biodegradabilidad. Sin embargo, su principal desventaja son los elevados costos asociados a su producción. En la presente revisión se describen las propiedades químicas y microbiológicas de tensoactivos y biotensoactivos, así como las diferentes aplicaciones de los últimos, principalmente en el campo de la biorremediación. Además, se analiza la influencia de las principales variables de proceso sobre la producción de biotensoactivos, en particular de los ramnolípidos provenientes de Pseudomonas aeruginosa.
OBTENCIóN DE AZúCARES FERMENTABLES MEDIANTE HIDRóLISIS áCIDA DE Beta vulgaris L.
Donaji JIMéNEZ ISLAS,Arturo ABREU CORONA,Víctor E. LóPEZ Y LóPEZ,Alejandro TELLEZ JURADO
Revista internacional de contaminación ambiental , 2012,
Abstract: Con el propósito de incrementar la cantidad de azúcares que beneficie el rendimiento de etanol en la fermentación, se realizó la hidrólisis de Beta vulgaris L. con H2SO4. Se evaluó el efecto que tienen los parámetros: agitación, concentración de ácido, masa y temperatura sobre el grado de hidrólisis del sustrato. La masa se probó en el intervalo de 5 hasta 40 g y la agitación de 100 a 250 rpm. La temperatura y el tiempo de reacción fueron evaluados en el intervalo de 30 a 90 oC y de 2 a 6 h, respectivamente. El tama o de partícula probado fue de 0.5 mm y para todos los casos el volumen de reacción de 50 mL. A una velocidad de 150 rpm se tuvo mayor efecto de hidrólisis. Mediante comparación de medias se determinó que las concentraciones superiores a 0.5 N de H2SO4 no tienen efecto significativo (p<0.05) sobre la liberación de azúcares totales. Con 10 g de sustrato en los medios de reacción se obtuvo el mayor rendimiento de hidrólisis. La temperatura de 90 oC proporcionó la mayor hidrólisis, y con 50 oC la cantidad de azúcares totales fue 3 g/L menor a la generada en 90 oC. Las mejores condiciones del dise o del experimento fueron; 40 oC, 150 rpm y 10 g de sustrato. El incremento en el tiempo de reacción indicó que se lleva a cabo la degradación de hemicelulosa dentro de la matriz del sustrato y se generan regiones amorfas que promueven la disponibilidad de la celulosa.
Tratamiento anaerobio de desechos lácticos y estiércol de cabra
Maga?a-Ramírez,J. Luis; Rubio-Nú?ez,Rubria; Jiménez-Islas,Hugo;
Ingeniería e Investigación , 2011,
Abstract: anaerobic digestion was carried out to obtain biogas from lactic waste in combination with goat manure. waste from lactic products such as cream, cheese and whey was mixed with goat manure using three formulations; the quantity of waste from cream and cheese was maintained, and only the quantity of manure and whey was varied. methanogenic bacteria obtained from predigestion of goat manure were used as inoculants. temperature was 35°c and ph 7.0.biogas methane percentage was determined by gas chromatography. the results showed that the highest methane concentration obtained was 82% with formulation iii.
Anaerobic treatment of lactic waste and goat manure Tratamiento anaerobio de desechos lácticos y estiércol de cabra
Maga?a-Ramírez J. Luís,Rubio-Nú?ez Rubria,Jiménez-Islas Hugo,Martínez-García Martín T.
Ingeniería e Investigación , 2011,
Abstract: Anaerobic digestion was carried out to obtain biogas from lactic waste in combination with goat manure. Waste from lactic products such as cream, cheese and whey was mixed with goat manure using three formulations; the quantity of waste from cream and cheese was maintained, and only the quantity of manure and whey was varied. Methanogenic bacteria obtained from predigestion of goat manure were used as inoculants. Temperature was 35oC and pH 7.0.Biogas methane percentage was determined by gas chromatography. The results showed that the highest methane concentration obtained was 82% with formulation III. Se realizó una digestión anaerobia para la obtención de biogás a partir de residuos lácteos de crema, queso y suero de leche en combinación con estiércol de cabra, mediante el desarrollo de tres formulaciones, manteniendo constante la cantidad de los desechos de crema y queso y variando la cantidad de excreta de cabra y suero de leche. Se utilizó un inóculo de bacterias metanogénicas obtenido partir de una predigestión de estiércol de cabra. La temperatura de operación fue de 35 oC, con un pH de 7,0, determinándose el porcentaje de metano en el biogás por medio de cromatografía de gases. Los resultados mostraron que la mayor concentración de metano fue de 82%, obtenida con la formulación número tres.
Brain empyema due to Escherichia coli in a 5 month-old infant: a case report and literature review
José A. Madrid Gómez Tagle,Pablo Pacheco-Hernández,Vania G. Jiménez-Islas,Citlali A. Hernández López
Medwave , 2012,
Abstract: Introduction: Brain empyema in children is a rare intracranial infection that may result from meningitis, sinusitis, or mechanisms such as head trauma, neurological surgery or hematogenous spread from a remote site. Objective: To describe a case of brain empyema caused by Escherichia coli in an infant. Methodology: A case report is presented with isolation of Escherichia coli arising after the overlap period of meningitis (1-3 months). A literature review of the risk factors, etiology and treatment of brain empyema in children is conducted. Results: The case report is about a 5 month-old male infant with no history of immunodeficiency, plagiocephalic, and with a 3 week-long history of otitis prior to admission. The patient had fever, seizures and rostro-caudal deterioration, cerebrospinal fluid pleocytosis and hypoglycorrhachia. The tomographic images revealed brain empyema. It was posible to isolate Escherichia coli from culture and surgical drainage was required plus systemic antibiotic therapy for 4 weeks. Conclusions: Brain empyema caused by Escherichia coli in infants after the overlap period are very rare. Treatment consists in prompt surgical evacuation, eradication of the primary infection and proper administration of systemic antimicrobials.
Estudio numérico del efecto de la temperatura ambiental en la convección natural bidimensional en el almacenamiento de granos en silos cilíndricos
Carrera-Rodríguez, M;Martínez-González, G. M.;Navarrete-Bola?os, J.L.;Botello-álvarez, J.E.;Rico-Martínez, R.;Jiménez-Islas, H.;
Revista mexicana de ingeniería química , 2009,
Abstract: a numerical study on the dynamics of grain storage in cylindrical silos was performed based on transport equations of momentum and energy for multiphase media. the purpose of this study is to analyze simultaneously the effect of the heat of respiration and three types of boundary conditions; two of them constants (case i, θ =1 and case ii, θ =0) and a time-dependent (case iii, simulating the change of temperature along the day-night cycle) on the flow patterns, the isotherms and heat transfer to the environment. the governing equations were solved via spatial discretization using second order finite differences and time discretization using an implicit scheme. the set of algebraic equations generated was solved using nonlinear relaxation. in this simulation, the thermodynamic properties of sorghum grain stored in a silo of 44 m3 grain capacity were used. stability for case i and ii, were reached in a dimensionless time (fo) equals 0.3 (that is equivalent a real time of 3.01 h), while for case iii was for fo = 20 (equivalent to 200.88 h) because the periodicity of the boundary condition. for cases ii and iii, the boundary conditions induce the formation of multicellular flow.
Estudio numérico de la convección natural en una cavidad cuadrada en 2-D con interfase fluido-medio poroso y generación de calor
Jiménez-Islas, H.;Calderón-Ramírez, M.;Navarrete-Bola?os, J.L.;Botello-álvarez, J.E.;Martínez-González, G.M.;López-Isunza, F.;
Revista mexicana de ingeniería química , 2009,
Abstract: a numerical study was performed regarding two-dimensional natural convection in a square cavity that contains two horizontal regions formed by a homogeneous fluid and an isotropic heat-generating porous medium. the one-domain formulation was used for developing the mathematical model, with a binary parameter so as to the momentum and energy equations were valid throughout the domain. the governing equations were discretized using orthogonal collocation and the set of algebraic equations generated is solved via newton method. the simulations were performed for rayleigh numbers among 103 and 106; for values of the dimensionless heat source (s0) of 0, 10, 30, and 50; darcy numbers of 10-4, 10-6, and 10-8 and for positions of the porous medium-fluid interface between 0< yp < 1, considering the prandtl number equals to 0.71, to assess their effect on the streamlines, isotherms and nusselt number. in addition, this method was compared with previously published reports with good agreement. the results indicate that the one-domain formulation is a good approximation for predicting the flow between the two phases without the requirement to specify interfacial conditions.
Organic Wastes to Increase CO2 Absorption  [PDF]
Manuel Jiménez Aguilar
International Journal of Clean Coal and Energy (IJCCE) , 2014, DOI: 10.4236/ijcce.2014.34005
Abstract: The objective of the study was actually the investigation of the effect of various organic wastes on the ability of urine in absorbing CO2. Urine alone or mixed with olive-oil-mill waste waters (O), poultry litter (P) or meat bone meal (M) was used on the absorption of CO2 from a gas bottle. The absorption capacity (1.35 - 2.85 gCO2/gNH4) was bigger than other solvents such as ammonia and amines. The range of CO2 absorption was significantly bigger for the organic mixtures P and PM with urine (9.1 - 11.8) g/L than urine alone 6.5 g/L. These organic wastes could be used to increase CO2 absorption in urine and reduce gas emissions.
Algorithms of the Femtoscope: KeV X-Rays Cure Cancer While MeV X-Rays Only Burn the Cells  [PDF]
Edward Jiménez Calderon
American Journal of Computational Mathematics (AJCM) , 2018, DOI: 10.4236/ajcm.2018.84023
Abstract: The study of cancer with the Femtoscope shows us that the information of the cell nucleus is correlated with the atomic nucleus. Femtoscope and entropy algorithms monitor the time and energy of x-rays that transform cancer cells into healthy cells and vice versa. Curing cancer means recovering the information lost from a cancer cell, leading to a minimum entropy. The efficient treatment of cancer presents resonance frequencies in the production and elimination of cancerous cells, asymmetrically. The cure asymmetry of cancer is due to the support of DNA repair genes, allowing the stability of a race or species, and prioritizing life to death. Using the Femtoscope and Spectroscopy, we experimentally validate the resonance frequencies, which effectively cure the cancer and find the optimal times and doses of treatment. In this way, we minimize collateral effects and unnecessary economic costs. In addition, the phosphorus resonance demonstrates why the low energies of x-rays cure cancer and high x-ray energies only burn cancer cells.
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