D.F., Mexico
D.F., Mexico

Time filter

Source Type

Rodriguez V.,CINVESTAV | Valdez-Perez M.D.L.A.,CINVESTAV | Luna-Guido M.,CINVESTAV | Ceballos-Ramirez J.M.,CINVESTAV | And 5 more authors.
Applied Soil Ecology | Year: 2011

Liming or vermicomposting eliminates pathogens from wastewater sludge, but might affect CO2 and N2O emissions when added to soil. Soil incubated at 40%, 60%, 80% and 100% of its water holding capacity (WHC) was amended with limed or unlimed wastewater sludge, vermicompost or inorganic fertilizer, while emissions of N2O and CO2 and mineral N concentrations were monitored in aerobic incubation experiment for 7 days. Application of unlimed wastewater sludge significantly increased the emission of CO2 compared to the unamended soil, but not the other treatments except when unlimed wastewater sludge was added to soil incubated at 60% WHC. The emission of CO2, was generally largest in soil incubated at 60% WHC and lowest in soil incubated at 100% WHC. The emission of N2O after 1 day was significantly larger in soil amended with unlimed wastewater sludge compared to the other treatments, but not when soil was incubated at 100% WHC. The emission of N2O increased with increased soil water content. The concentration of NH4 + was largest in soil amended with limed or unlimed wastewater sludge and lowest in the unamended soil and soil water content had no clear effect on it. In soil incubated at 40%, 60% and 80% WHC, the largest amount of NO3 - was found in soil amended with inorganic fertilizer and vermicompost and the lowest in the soil amended with unlimed wastewater sludge. The concentration of NO3 - in soil decreased when the soil water content increased in all treatments, except in the soil amended with unlimed wastewater sludge. It was found that water content affected the emission of CO2 of N2O and the concentration of NO3 -, but not the amount of NH4 + and NO2 - in soil. Application of unlimed wastewater sludge increased the emissions of CO2 and N2O and the concentrations of NH4 +, but decreased the amount of NO3 - in soil. © 2011 Elsevier B.V.

Lopez-Munoz G.A.,Quimica Aromatica SA | Lopez-Munoz G.A.,CINVESTAV | Balderas-Lopez J.A.,UPIBI IPN | Ortega-Lopez J.,CINVESTAV | And 2 more authors.
Nanoscale Research Letters | Year: 2012

The thermal properties of nanofluids are an especially interesting research topic because of the variety of potential applications, which range from bio-utilities to next-generation heat-transfer fluids. In this study, photopyroelectric calorimetry for measuring the thermal diffusivity of urchin-like colloidal gold nanofluids as a function of particle size, concentration and shape in water, ethanol and ethylene glycol is reported. Urchin-like gold nanoparticles were synthesised in the presence of hydroquinone through seed-mediated growth with homogeneous shape and size ranging from 55 to 115 nm. The optical response, size and morphology of these nanoparticles were characterised using UV-visible spectroscopy and transmission electron microscopy. The thermal diffusivity of these nanofluids decreased as the size of the nanoparticles increased, and the enhancement depended on the thermal diffusivity of the solvent. The opposite effect (increase in thermal diffusivity) was observed when the nanoparticle concentration was increased. These effects were more evident for urchin-like gold nanofluids than for the corresponding spherical gold nanofluids. © 2012 López-Muñoz et al.

Garcia A.,CINVESTAV | Luviano-Juarez A.,CINVESTAV | Chairez I.,UPIBI IPN | Poznyak A.,CINVESTAV | Poznyak T.,Section of Research and Postgraduate Studies
International Journal of Artificial Intelligence | Year: 2011

Chaotic systems arise in many different fields, being their modeling, synchronization and control, important topics for interested researchers in this kind of systems. The present paper deals with the problem of non-parametric identification (adaptable modeling) of a class of uncertain nonlinear systems with chaotic behavior. A Projectional Dynamic Neural Network (PDNN) is proposed to carry out the identification task. The practical stability of the identification error is proven by the second Lyapunov's method and the Linear Matrix Inequalities approaches. The obtained algorithm is tested by numerical simulations, taking into account the mathematical model of the so-called chaotic Chuas circuit, and compared with a nonlinear observer (Thaus observer). Then, a reported version of the Chua's circuit is constructed to verify the proposed identification scheme under an experimental framework. PDNN is tested with this real data. In both cases, simulation and real measurements, the developed algorithm shows an excellent convergence to the state variables of the chaotic system, fact that is supported by the formal analysis. Copyright © 2011 by IJAI.

Perez-Cruz J.H.,University of Guadalajara | Chairez I.,UPIBI IPN | De Jesus Rubio J.,Seccion de Estudios de Posgrado e Investigacion | Pacheco J.,Seccion de Estudios de Posgrado e Investigacion
IET Control Theory and Applications | Year: 2014

In this study, a neuro-controller with adaptive deadzone compensation for a class of unknown SISO non-linear systems in a Brunovsky form with uncertain deadzone input is presented. Based on a proper smooth parameterisation of the deadzone, the unknown dynamics is identified by using a continuous time recurrent neural network whose weights are adjusted on-line by stable differential learning laws. On the basis of this neural model so obtained, a feedback linearisation controller is developed in order to follow a bounded reference trajectory specified. By means of Lyapunov analysis, the boundedness of all the closed-loop signals as well as the weights and deadzone parameter estimations is rigorously proven. Besides, the exponential convergence of the actual tracking error to a bounded zone is guaranteed. The effectiveness of this scheme is illustrated by a numerical simulation. © The Institution of Engineering and Technology 2014.

Muniz-Ramirez A.,CINVESTAV | Perez-Gutierrez R.M.,Av Instituto Pol Nacional S N | Garcia-Baez E.,UPIBI IPN | Mota-Flores J.M.,Av Instituto Pol Nacional S N
Boletin Latinoamericano y del Caribe de Plantas Medicinales y Aromaticas | Year: 2014

Two compounds from the hexane extract of seeds of Byrsonima crassifolia were isolated and their structures elucidated using extensive spectroscopic analyses. These compounds are derived from the new labdane diterpene Labda-17-(1) and the known antimicrobial Labda-8 (17)-(2). The present study was aimed to study the effect antimicrobial of novel diterpene 1 against bacterial pathogens showed a moderate activity with MIC values 18.79-70.12 μg/ml and a MBC ranging between 250-1000 μg/ml against all assayed microorganisms. © 2014.

Oliver-Tolentino M.A.,UPIBI IPN | Arce-Estrada E.M.,UPALM | Cortes-Escobedo C.A.,Research Center e Innovacion Tecnologica Del | Bolarin-Miro A.M.,Autonomous University of the State of Hidalgo | And 3 more authors.
Journal of Alloys and Compounds | Year: 2012

In the present work, results of electrochemical evaluation, as well as morphological and structural characterization of Ni xW 1-x materials with x = 0.77, 0.64, 0.4, 0.19 and 0.07 processed by means of high energy ball milling from high purity powders are presented. Also, the electrocatalytic performance on the hydrogen evolution reaction (HER) of the Ni xW 1-x materials evaluated by linear polarization and cyclic voltammetry techniques in alkaline media at room temperature is discussed. The structural and morphological characterization of the as-prepared materials was carried out using X-ray diffraction (XRD) and scanning electron microscopy (SEM). Results indicated a small-particle clusters and solid solution formation. According to the kinetics parameters the best electrocatalytic activity was observed at Ni 64W 36. © 2011 Elsevier B.V. All rights reserved.

Valdez-Perez M.A.,CINVESTAV | Fernandez-Luqueno F.,CINVESTAV | Franco-Hernandez O.,UPIBI IPN | Flores Cotera L.B.,CINVESTAV | Dendooven L.,CINVESTAV
Scientia Horticulturae | Year: 2011

Wastewater sludge can be vermicomposted to increase its nutrient content and reduce pathogens. The effect of vermicompost wastewater sludge on soil characteristics and growth of bean plants (Phaseolus vulgaris L.) was compared with that of inorganic fertilizer, untreated sludge or sludge treated with lime to pH 12. Plants cultivated in vermicompost amended soil developed best while those amended with inorganic fertilizer least. Bean plants grown in the unlimed amended soil had the highest total N content of 3.97gkg-1, but only 6 active and 8 total nodules. Plants cultivated in unamended soil and added with inorganic fertilizer had >20 active and total nodules, but ≤2.12gNkg-1 dry plant. It was found that limed and unlimed sludge stimulated development of bean plants to a larger extent than those cultivated in inorganic fertilized soil or unamended soil in the greenhouse, but less than those cultivated in vermicompost amended soil. © 2011 Elsevier B.V.

Tetlalmatzi G.,UPIBI IPN | Contreras J.G.,CINVESTAV | Larios F.,CINVESTAV | Perez M.A.,CINVESTAV
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2010

We study the discovery potential of the flavor-changing neutral coupling (FCNC) htc of the Higgs boson and the top quark through the rare tree-body decay h→Wbc at muon colliders for a light Higgs boson with mass 114≤mh≤145GeV. This decay mode may compete with the standard model (SM) background induced by the hWW coupling in some models with a tree-level htc coupling and with models that predict this coupling at the one-loop level in the range 10-2-10-1. A future muon collider could test the scalar FCNC decay t→hc via Higgs decay h→t*c→bW +c down to values of the coupling gtc=0.5 [that are equivalent to BR(t→hc)∼5×10-3]. The LHC could probe values of gtc 1 order of magnitude smaller, unless other processes beyond the SM appear that through intense multijet activity may clutter the t→hc signal. © 2010 The American Physical Society.

Lopez-Munoz G.A.,Quimica Aromatica SA | Pescador-Rojas J.A.,CINVESTAV | Ortega-Lopez J.,CINVESTAV | Salazar J.S.,CINVESTAV | Abraham Balderas-Lopez J.,UPIBI IPN
Nanoscale Research Letters | Year: 2012

In recent times, nanofluids have been studied by their thermal properties due to their variety of applications that range from photothermal therapy and radiofrequency hyperthermia (which have proven their potential use as coadjutants in these medical treatments for cancer diseases) to next-generation thermo-fluids. In this work, photoacoustic spectroscopy for a specific study of thermal diffusivity, as a function of particle size and concentration, on colloidal water-based gold nanofluids is reported. Gold nanoparticles were synthetized in the presence of hydroquinone through a seed-mediated growth with homogenous sizes and shapes in a range of 16 to 125 nm. The optical response, size and morphology of these nanoparticles were characterized using ultraviolet-visible spectroscopy and transmission electron microscopy, respectively. Thermal characterizations show a decrease in the thermal diffusivity ratio as the nanoparticle size is increased and an enhancement in thermal diffusivity ratio as nanoparticle concentration is added into the nanofluids. Compared with other techniques in the literature such as thermal lens and hot wire method, this photoacoustic technique shows an advantage in terms of precision, and with a small amount of sample required (500 μl), this technique might be suitable for the thermal diffusivity measurement of nanofluids. It is also a promising alternative to classical techniques. © 2012 López-Muñoz et al.; licensee Springer.

Lopez-Munoz G.A.,Quimica Aromatica SA | Balderas-Lopez J.A.,UPIBI IPN
Thermochimica Acta | Year: 2014

Photothermal techniques were used to study thermal diffusivity, thermal effusivity, thermal conductivity and specific heat of folded and non-folded citrus essential oils and their corresponding terpenes; the latter are derivatives of the folding process. Experimental results show that thermal properties of all citrus essential oils are comparable. However due to a decrease on d-limonene and other monoterpenes with the folding process, thermal properties of folded citrus oils are higher than those for unfolded citrus oils. Moreover, thermal properties of various citrus terpenes are lower than those of folded and unfolded citrus oils. Analysis of variance (ANOVA) reveals significant differences (p < 0.05) among means for thermal data with the folding degree and fruit type for citrus oils. Valued obtained in this work, most of them not available in the literature thus far, together with values expected to emerge from future photothermal calorimetric experiments, might be used in the modelling and design of distillation columns, reboilers and heat exchangers all being parts of equipment used for citrus oils processing at industrial scale. © 2014 Elsevier B.V.

Loading UPIBI IPN collaborators
Loading UPIBI IPN collaborators