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Search Results: 1 - 10 of 241931 matches for " Antonino Pérez-Hernández "
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Comparación de dos sistemas anaerobios acoplados para la biometanización de la fracción orgánica de residuos sólidos urbanos
M,Liliana; Gaviria,Alzate; Pérez-Hernández,Antonino; Nevárez-MOorillón,Virginia G; Rinderknecht-Seijas,Noemí; Poggi-Varaldo,Héctor M;
Interciencia , 2003,
Abstract: two lab-scale mesophilic systems for the anaerobic digestion of the organic fraction of municipal solid wastes (ofmsw) were compared. one system (re-re) consisted of two coupled reactors packed with ofmsw and the other (uasb-re) consisted of an upflow anaerobic sludge blanket reactor (uasb) coupled to a packed reactor. for the start-up phase, both leading reactors re 1.1 and uasb 2.1 were inoculated with a mixture of non-anaerobic inocula and worked with leachate and effluent full recirculation. once a full methanogenic regime was achieved in the leading reactors, their effluents were fed to fresh packed reactors re 1.2 and re 2.2. re 1.1 reached its full methanogenic regime after 118 days (tmf, time to achieve methanogenesis). at this point, its leachate had ph 7.05, alpha factor 0.35, volatile organic acids (voa) 1405mg/l hac, cod 3080mg/l and 62.02% methane in the biogas. the other leading reactor (uasb 2.1) reached its full methanogenesis regime after 34 days, and its effluent had ph 7.13, alpha 0.36, voa 1289mg/l hac, cod 2280mg/l, and 60.40% methane in the biogas. after coupling the leading reactors to the corresponding packed reactors, both coupled anaerobic systems showed similar performances regarding the degradation of ofmsw. the uasb-re system showed a faster overall start-up, a slightly higher reduction of organic matter (as volatile solids, vs) of the packed ofmsw and a higher biogas production than re-re. removal efficiencies of vs and cellulose, and the methane pseudo yield were 85.95%, 80.88% and 0.109l ch4/g-vsfed in re-re, and 88.75%, 82.61% and 0.115l ch4/g-vsfed in ranmal-re.
Computational molecular characterization of the flavonoid rutin
Sergio A Payán-Gómez, Norma Flores-Holguín, Antonino Pérez-Hernández, Manuel Pi?ón-Miramontes, Daniel Glossman-Mitnik
Chemistry Central Journal , 2010, DOI: 10.1186/1752-153x-4-12
Abstract: Flavonoids are phenolic substances characterized for a low molecular weight and they are abundant in plant tissues, apple being one of the most important (particularly its skin) [1,2]. In the human body they show a lot of biological properties as antioxidants, antiallergenic, antibacterial, antifungal, antiviral and anticarcinogenic agents. These characteristics confer to them pharmacological properties useful for the treatment of diseases that go from allergies, bacterial and viral infectious processes, to those of greater risk like the coronary diseases, cancer and HIV [3-5]. The mechanism by which flavonoids carry out their properties, mainly their antioxidant power, is either by inhibiting the formation or activity of reactive oxygen species, or by direct interaction with DNA, enzymes and membrane receptors.Theoretical investigations of the physical and chemical properties of flavonoids are very important in order to disclose the relationship between the structure, properties and performance, and to help in the design and synthesis of new derivatives with improved properties. We have experimentally found that some natural flavonoids have a strong ability for complexing metal ions, in particular, those related to heavy metals [6-8]. Thus, natural flavonoids could be useful in water treatment, cleaning and purification. The objective of this letter is to report the results of the calculation of the molecular structure and properties of the flavonoid Rutin using a recently developed density functional [9]. The IR and UV-Vis spectra, the dipole moment and polarizability, the free energy of solvation in different solvents as an indication of solubility, the HOMO and LUMO orbitals, and the chemical reactivity parameters that arise from Conceptual DFT [10,11] are reported. The calculated values are compared with the available experimental data for this molecule as a means of validation of the used model chemistry. The spectra and the calculated values are important in
Las clasificaciones e hipótesis biogeográficas para la guayana venezolana
Pérez-Hernández,Roger; Lew,Daniel;
Interciencia , 2001,
Abstract: summary from the publications of the earliest naturalists up until our own day, many attemps have been made to describe, classify and explain the origin and distribution of the venezuelan flora and fauna. although these works unleashed great debates deriving from the different hypotheses which are the theoretical basis of biogeography, these efforts have undoubtedly made decisive contributions to the advancement of biogeography as a science. given their varying perspectives and their greater or lesser degrees of concordance, these different phytogeographical and zoogeographical proposals are providing an ever-clearer picture of venezuelan biogeography. one point upon which most of these proposals concur is the recognition of the distinct biogeographical identity of the guayanan region, whose outstanding biology, geography and geological history have resulted in more biogeographical proposals and theories than for any other part of the country. in this work, we present a compilation of the different phyto- and zoogeographic classifications that have been proposed for the venezuelan guayana region, and we detail and discuss the hypotheses that have tried to explain the origin and current distribution of the organisms of this area.
Red cell distribution width in patients with HIV infection  [PDF]
María L. Gallego, Isabel A. Pérez-Hernández, Rosario Palacios, Josefa Ruiz-Morales, Enrique Nu?o, Manuel Márquez, Jesús Santos
Open Journal of Internal Medicine (OJIM) , 2012, DOI: 10.4236/ojim.2012.21002
Abstract: Objective: To examine the association between elevated levels of red cell distribution width (RDW) and cardiovascular risk factors (CVRF) and metabolic syndrome (MS) in HIV-patients. Methods: Cross-sectional study including all asymptomatic HIV-outpatients under follow-up during 2007. Patients completed a questionnaire about CVRF, underwent a physical examination, and an 8-hour fasting blood analysis. Elevated RDW was defined as ≥75th percentile. Patients with and without an elevated RDW were compared. Results: 666 patients (79.3% men) were included: mean age 44.7 years, mean CD4 506/mm3 and 87.5% on antiretroviral therapy (85.3% with undetectable viral load). Mean RDW was 13.7% (range: 7.7% - 33.6%; 75th percentile, 14.1%). The prevalence per quartile of MS was 15.7%, 9.3%, 18.8% and 16.6% and of patients with CVRF > 20% was 8.4%, 4.0%, 4.4%, and 6.4%, respectively (p > 0.05); 23.4% of the patients had an elevated RDW (>14.1%). The top percentile of RDW was associated with AIDS (OR 1.6; 95% CI, 1.0 - 2.4; p = 0.02), detectable viral load (OR 1.5; 95% CI, 1.01 - 2.4; p = 0.04) and hypertension (OR 2.3; 95% CI, 1.4 - 4.0; p = 0.001). Conclusions: In HIV-outpatients, higher RDW is related with detectable viral load and with AIDS. Although it was associated with hypertension, we found no relation with MS nor with higher cardiovascular risk.
Physicochemical and Functional Properties of Dehydrated Japanese Quail (Coturnix japonica) Egg White  [PDF]
Maira Segura-Campos, Roberto Pérez-Hernández, Luis Chel-Guerrero, Arturo Castellanos-Ruelas, Santiago Gallegos-Tintoré, David Betancur-Ancona
Food and Nutrition Sciences (FNS) , 2013, DOI: 10.4236/fns.2013.43039
Abstract:

Physicochemical, functional and digestibility analyses were done of dehydrated quail egg white to determine its possible practical applications. Quail egg white was dehydrated by air convection using one of two temperatures and times: M1 (65, 3.5 h), M2 (65, 5.0 h), M3 (70, 3.5 h) and M4 (70, 5.0 h). Lyophilized quail egg white was used as a standard. All four air-dried treatments had good protein levels (92.56% to 93.96%), with electrophoresis showing the predominant proteins to be lysozyme, ovalbumin and ovotransferin. Denaturation temperatures ranged from 81.16 to 83.85 and denaturation enthalpy values from 5.51 to 9.08 J/g. Treatments M1-4 had lower water-holding (0.90 - 2.95 g/g) and oil-holding (0.92 - 1.01 g/g) capacities than the lyophilized treatment (4.5 g/g, 1.95 g/g, respectively). Foaming capacity was pH-dependent in all five treatments, with the lowest values at alkaline pH and the highest (153% to 222%) at acid pH (pH 2). Foam stability was lowest at acid pH and highest at alkaline pH. Emulsifying activity in the air-dried treatments was highest at pH 8 (41% - 46%). Emulsion stability was pH-dependent and

Characterization of the minimal penalty of a convex risk measure with applications to Levy processes
Daniel Hernández-Hernández,Leonel Pérez-Hernández
Mathematics , 2012,
Abstract: The minimality of the penalization function associated with a convex risk measure is analyzed in this paper. First, in a general static framework, we provide necessary and sufficient conditions for a penalty function defined in a convex and closed subset of the absolutely continuous measures with respect to some reference measure $\mathbb{P}$ to be minimal. When the probability space supports a L\'{e}vy process, we establish results that guarantee the minimality property of a penalty function described in terms of the coefficients associated with the density processes. The set of densities processes is described and the convergence of its quadratic variation is analyzed.
Robust utility maximization for Lévy processes: Penalization and solvability
Daniel Hernández-Hernández,Leonel Pérez-Hernández
Quantitative Finance , 2012,
Abstract: In this paper the robust utility maximization problem for a market model based on L\'evy processes is analyzed. The interplay between the form of the utility function and the penalization function required to have a well posed problem is studied, and for a large class of utility functions it is proved that the dual problem is solvable as well as the existence of optimal solutions. The class of equivalent local martingale measures is characterized in terms of the parameters of the price process, and the connection with convex risk measures is also presented.
Cálculo de lente intraocular en casos complicados: el método ?Silguero?
Pérez-Silguero,D; Pérez-Silguero,MA; Pérez-Hernández,FR;
Archivos de la Sociedad Espa?ola de Oftalmología , 2005, DOI: 10.4321/S0365-66912005001000006
Abstract: purpose: to report a new method for intraocular lens (iol) calculation in patients treated by corneal refractive surgery, in whom the application of other methods is not possible because of the absence of necessary data. this method is also applicable in other situations where the iol calculation is difficult and in cases of iol exchange because of unexpected refractive difficulties. methods: we performed phaco-emulsifications, refracting the patient?s eye before iol implantation, using the refraction data in aphakia as the only variable for the application of the formula, which itself is based on the existing correlation between the graduation of glasses (12 mm) and the iol power at the lens level. the formula has been applied in 3 patients in whom no other calculation method was applicable. results: after the appropriate intervention, the 3 patients presented a spherical equivalent below 1 diopter. conclusion: we believe this formula is valid in some situations where other formulas cannot be applied because of the absence of the necessary variables.
Cálculo de lente intraocular en casos complicados: el método Silguero Intraocular lens power calculation in complicated cases: the Silguero method
D Pérez-Silguero,MA Pérez-Silguero,FR Pérez-Hernández
Archivos de la Sociedad Espa?ola de Oftalmología , 2005,
Abstract: Objetivo: Mostrar un nuevo método para el cálculo de la lente intraocular (LIO) en pacientes intervenidos de cirugía refractiva corneal en los que la aplicación de otros métodos no es posible por la falta de datos. También es aplicable en otras situaciones de alta dificultad en el cálculo de la LIO y en casos de intercambio de LIO por sorpresa refractiva. Métodos: Se realiza la facoemulsificación y antes de implantar la LIO se refracciona al paciente, utilizando el dato de la refracción en afaquia como única variable para la aplicación de nuestra fórmula, que se basa en la correspondencia existente entre la graduación en gafas (12 mm) y la potencia de la LIO a nivel de plano cristaliniano. Se ha aplicado en tres pacientes en los que ningún método de cálculo era aplicable. Resultados: Los tres pacientes han quedado con un equivalente esférico inferior a 1 dioptría. Conclusiones: Creemos que esta fórmula es válida para algunas situaciones en que otras fórmulas no pueden ser aplicadas por falta de variables. Purpose: To report a new method for intraocular lens (IOL) calculation in patients treated by corneal refractive surgery, in whom the application of other methods is not possible because of the absence of necessary data. This method is also applicable in other situations where the IOL calculation is difficult and in cases of IOL exchange because of unexpected refractive difficulties. Methods: We performed phaco-emulsifications, refracting the patient’s eye before IOL implantation, using the refraction data in aphakia as the only variable for the application of the formula, which itself is based on the existing correlation between the graduation of glasses (12 mm) and the IOL power at the lens level. The formula has been applied in 3 patients in whom no other calculation method was applicable. Results: After the appropriate intervention, the 3 patients presented a spherical equivalent below 1 diopter. Conclusion: We believe this formula is valid in some situations where other formulas cannot be applied because of the absence of the necessary variables.
Real Decreto de prescripción y dispensación de estupefacientes Real Decreto prescribing and dispensing of drug
J. Pérez-Cajaraville,C. Pérez-Hernández
Revista de la Sociedad Espa?ola del Dolor , 2013,
Abstract:
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