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American Journal of Plant Sciences 2014年第3期5卷 286-293页

作者： Maira Segura-Campos Enrique Barbosa-Martín Angel Matus-Basto Diana Cabrera-Amaro María Murguía-Olmedo Yolanda Moguel-Ordonez David Betancur-Ancona facultad de ingeniería Química Universidad Autónoma de YucatánYucatanMexico Instituto Nacional de Invesigaciones Forestales Agrícolas y Pecuarias(INIFAP)YucatanMexico

The leaf powders from two varieties of Stevia rebaudiana (Bertoni) cultivated in Yucatan, Mexico were analyzed for their proximate composition, dietary fiber composition and functional properties. The leaf powders were a good source of carbohydrates (64.06%-67.98%), protein (12.11%-15.05%), and crudefiber (5.92%-9.52%). Total dietary fiber content in the S. rebaudiana leaf powders were 28.61 (Morita II) and 29.12 (Criolla) g/100g sample, with most of this content represented by insoluble dietary fiber 87.79% (Morita II) and 70.02% (Criolla). Neutral detergent fiber (NDF), acid detergent fiber (ADF) and acid detergent lignin (ADL) were higher in Criolla (19.29%, 17.77%, 8.98%) than Morita II variety (18.11%, 14.16%, 2.28%). Hemicellulose and cellulose were higher in Morita II (3.96%, 11.78%) than criolla variety (1.51%, 8.79%). Functional properties of leaf powder from Morita II and Criolla were, water-holding capacity (2.87-4.07 g/g sample), oil-holding capacity (6.49-6.79 g/g sample), water-absorption capacity (3.41-3.44 g/g sample), water-adsorption capacity (0.25-0.28 g/g sample), and organic molecule absorption capacity (1.13-1.81 g/g sample). These suggest that S. rebaudiana (Bertoni) leaf powders may be used as dietary supplement or as food additive.

关键词： Stevia rebaudiana(Bertoni) Physico-Chemical Properties Dietary Fiber Functional Properties

Meyer-Neldel Rule in Plasma Polythiophene Thin Films

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Open Journal of Polymer Chemistry 2014年第3期4卷 31-37页

作者： J. Cuauhtemoc Palacios M. Guadalupe Olayo Guillermo J. Cruz J. A. Chávez-Carvayar departamento de Física Instituto Nacional de Investigaciones Nucleares Ocoyoacac México facultad de ingeniería Universidad Autónoma del Estado de México Toluca México.

In polymers, the electronic activation energy depends on the fragmentation, crosslinking, dopants, moisture and in general on the structure-environment interaction. This has a special importance in plasma polymers because fragmentation and crosslinking are usually higher than in other polymers. In this work, DC electrical conductivity of polythiophene thin films prepared by plasma (pPTh) was studied using the Meyer-Neldel (MN) rule to calculate the characteristic MN energy and temperature as a function of moisture and metallic dopants. The experimental data for pPTh synthesized in different conditions indicated that EM = 32 meV and TM = 373 K, suggesting a thermally activated conduction mechanism;however, in polymer-metal matrices with metal concentration higher than the percolation threshold, the conduction mechanism is different causing that the MN rule was only partially fulfilled. The congruence of the experimental data with the multiexcitation entropy model is discussed.

关键词： Polythiophene Plasma Conductivity Meyer-Neldel Rule Multi-Excitation Entropy Model

Life Cycle Assessment of Hydrogel Used in Hydroponics for the Impatiens New Guinea Production

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Open Journal of Applied Sciences 2016年第5期6卷 310-314页

作者： Silvia Paola Venegas Segura Martha Lilia Domínguez Patiño Miguel Aguilar Cortes Jorge Avelino Domínguez Patiño Luz Elva Marín Vaca Nadia Lara Ruiz Rosa María Melgoza Alemán Oscar Gabriel Villegas Torres facultad de Ciencias Químicas e ingeniería Universidad Autónoma del Estado de Morelos Cuernavaca México Centro de Investigación en ingeniería y Ciencias Aplicadas Universidad Autónoma del Estado de Morelos Cuernavaca México facultad de Ciencias Agropecuarias Universidad Autónoma del Estado de Morelos Cuernavaca México

The environmental impact on the planet leads to the search of new processes that are friendly with the environment and obtaining high quality products. In this sense, green chemistry is used in the generation of products through processes that do not affect the planet. In many of these processes and in general, the use of water has been depleted this resource of vital importance for the survival of living things. In Mexico, 77% of water is used in agriculture;14% in the public supply;5% in the thermoelectric plants and 4% in the industry. In research presented, hydroponics is essential in the process and is defined as a technique used to reduce excessive water consumption, by providing the necessary nutrients, in addition to preventing soil erosion by allowing the growth of plants without use of ground. The potassium polyacrylate is a super-absorbent polymer (Hydrogel) capable of absorbing water up to 500 times of its weight and has a life span of 10 years. When mixed with a substrate, the required nutrient solution potassium polyacrylate allows to lengthen the interval watering and thus reducing the consumption of water from plants. Morelos is the largest producer of ornamental plants in the country, due to its privileged climate and location. In the present work using the hydroponic methodology, we planted cuttings of Bethlehem New Guinea (Impatiens New Guinea) in a substrate made by 60% of coconut fiber, 20% tepojal, 20% ground sheet mixed with polymer of potassium (20 g per litre), 400 ml of Steiner nutrient solution in concentrations of 40%, 60%, 80% and 100%, varying the interval of 3-, 6-, 8- and 10-day watering. The variables considered are: concentration of chlorophyll, the plant height, leaf area, number of stems and weight dry total. The 12 principles of green chemistry applied to hydroponics using polyacrylate of potassium as part of the substrate in Bethlehem New Guinea (Impatiens New Guinea) to determine the analysis of life cycle (LCA), doing the bala

关键词： Steiner Solution Environmental Impact SimaPro

Pressure pulsation in Kaplan turbines:Prototype-CFD comparison

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Pressure pulsation in Kaplan turbines:Prototype-CFD comparis...

Intake, Energy Expenditure and Methane Emissions of Grazing Dairy Cows at Two Pre-Grazing Herbage Masses

The 26th IAHR Symposium on Hydraulic Machinery and Systems

作者： A Rivetti C Lucino1 S Liscia D Muguerza F Avellan Laboratorio de Hidromecánica Facultad de IngenieríaUniversidad Nacional de La Plata47 No200La PlataArgentina

Pressure pulsation phenomena in a large Kaplan turbine are investigated by means of numerical simulations （CFD） and prototype measurements in order to study the dynamic behavior of flow due to the blade passage and its interaction with other components of the *** simulations are performed with the commercial software Ansys CFX code,solving the incompressible Unsteady Reynolds-Averaged-Navier Stokes equations under a finite volume *** computational domain involves the entire machine at prototype *** care is taken in the discretization of the wicket gate overhang and runner blade *** measurements are performed using pressure transducers at different locations among the wicket gate outlet and the draft tube ***,CFD results are compared with temporary signals of prototype measurements at identical locations to validate the numerical model.A detailed analysis was focused on the tip gap flow and the pressure field at the discharge *** a rotating reference frame perspective,it is found that the mean pressure fluctuates accordingly the wicket gate ***,in prototype measurements the pressure frequency that reveals the presence of modulated cavitation at the discharge ring is distinguished,as also verified from the shape of erosion patches in concordance with the number of wicket gates.

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Open Journal of Animal Sciences 2021年第3期11卷 440-457页

作者： Cecilia Loza José Gere María Soledad Orcasberro Alberto Casal Mariana Carriquiry Paula Juliarena Efren Ramírez-Bribiesca Laura Astigarraga departamento de Producción Animal y Pasturas Facultad de Agronomía Universidad de la República Montevideo Uruguay Unidad de Investigación y desarrollo de las ingenierías UTNBA Facultad Regional de Buenos Aires CONICET Buenos Aires Argentina IFAS Facultad de Ciencias Exactas UNCPBA CONICET Tandil Argentina Colegio de Postgraduados Campus Montecillo Mexico City Mexico

A grazing experiment was undertaken to assess the effects of two levels of herbage mass (HM) on herbage DM intake (DMI), fat and protein corrected milk yield (FPCM), grazing behaviour, energy expenditure (HP), and methane emissions (CH4) of grazing dairy cows in spring. Treatments were a low HM (1447 kg DM/ha;LHM) or a high HM (1859 kg DM/ha;HHM). Pasture was composed mainly of cocksfoot (Dactylis glomerata) and lucerne (Medicago sativa), offered at a daily herbage allowance of 30 kg DM/cow, above 5 cm. Eight multiparous Holstein cows were used in a 2 × 2 Latin Square design in two 10-day periods. Despite the differences in pre-grazing HM between treatments, OM digestibility was not different (P = 0.28). Herbage mass did not affect DMI or FPCM. Grazing time was not different between treatments, but cows had a greater bite rate when grazing on LHM swards. However, HP did not differ between treatments. Daily methane emission (per cow), methane emission intensity (per kg FPCM) and methane yield (as percentage of gross energy intake) were not different. The lack of effect of the amount of pre-grazing HM on energy intake, confirms that the difference between HM treatments was beyond the limits that impose extra energy exp

关键词： Dairy Cow Herbage Mass Intake Grazing Behavior Methane

An Easy and Efficient Method to Functionalize Titanium Dioxide Nanoparticles with Maleic Anhydride

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Soft Nanoscience Letters 2014年第3期4卷 53-62页

作者： Pável C. Hernández del Castillo Saúl Robles Manuel Facundo Ruiz Doctorado Institucional en ingeniería y Ciencia de Materiales UASLP San Luis Potosí México facultad de Ciencias UASLP San Luis Potosí México

In this work, titanium dioxide (TiO2) nanoparticles were functionalized with maleic anhydride (MA), using a non-polar (toluene) and polar protic (ethanol) solvents. The concentrations of MA in the reaction were varied to obtain the desired degree of functionalization. The samples were characterized with Fourier Transform Infrared Spectroscopy (FTIR), Diffuse Reflectance UV-Vis Spectroscopy (DRS), Thermal Analysis (TGA-DTA) and Nitrogen Adsorption (BET). The physical adsorption of organic molecules was eliminated by washing a number of times in water. Chemical stability between solid-organic phases was confirmed by TOC and thermal analysis. FT-IR and DRS results clearly show the chemical adsorption of MA on the TiO2. The UV-Vis spectroscopy is claimed to be a suitable technique to determine the achievement of TiO2 functionalization. Two different adsorptions geometries of MA were proposed. The presence of MA on the surface TiO2 increases the band gap. These results imply that TiO2 can be excited with less energy and increase the absorption of light in the visible region. The effectiveness of the functionalized nanoparticles to interact with organic materials is currently being studied with the intention of applying them in the energy and environmental sanitation fields.

关键词： TiO2 Nanoparticles Functionalization Maleic Anhydride Sensitization Adsorption on Solid

Stability analysis of the extended state observers by Popov criterion

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Theoretical & Applied Mechanics Letters 2012年第4期2卷 40-43页

作者： Christiav Erazo Fabiola Angulo Gerard Olivar Universidad Nacional de Colombia-Sede Manizales-facultad de ingeniería y Arquitectura-departamento de ingeniería Elctrica Electrónica y Computación-Percepción y Control Inteligente-Bloque QCampus La NubiaManizales 170003Colombia

The analysis and design of the extended state observer （ESO） involves a continuous non-smooth structure, thus the study of the ESO dynamic requires mathematical tools of the nonlinear systems analysis. This paper establishes the sufficient conditions for absolute stability of the ESO. Based on this study, a methodology to estimate several nonlinear functions in dy- namics systems is proposed.

关键词： Popov criterion extended observer ESO

determination of the Normal Contact Stiffness and Integration Time Step for the Finite Element Modeling of Bristle-Surface Interaction

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Computers, Materials & Continua 2018年第7期56卷 169-184页

作者： Libardo V.Vanegas-Useche Magd M.Abdel-Wahab Graham A.Parker facultad de ingeniería Mecánica Universidad Tecnológica de Pereira.Pereira 660003Colombia Division of Computational Mechanics Ton Duc Thang UniversityHo Chi Minh CityVietnam Faculty of Civil Engineering Ton Duc Thang UniversityHo Chi Minh CityVietnam Soete Laboratory Faculty of Engineering and ArchitectureGhent UniversityTechnologiepark Zwijnaarde 903Zwijnaarde B-9052Belgium Faculty of Engineering and Physical Sciences University of Surrey.GuildfordUK

In finite element modeling of impact,it is necessary to define appropriate values of the normal contact stiffness,Kn,and the Integration Time Step(ITS).Because impacts are usually of very short duration,very small ITSs are ***,the selection of a suitable value of Kn is a critical issue,as the impact behavior depends dramatically on this *** this work,a number of experimental tests and finite element analyses have been performed in order to obtain an appropriate value of Kn for the interaction between a bristle of a gutter brush for road sweeping and a concrete ***,a suitable ITS is *** experiments consist of releasing a steel bristle that is placed vertically at a certain distance from a concrete surface and tracking the ***,in the finite element analyses,a beam is modeled in free fall and impacting a surface;contact and target elements are attached to the beam and the surface,*** results of the experiments and the modeling are integrated through the principle of conservation of energy,the principle of linear impulse and momentum,and Newton’s second *** results demonstrate that,for the case studied,Kn and the impact time tend to be independent of the velocity just before impact and that Kn has a very large variation,as concrete is a composite material with a rough ***,the ratio between the largest height of the bristle after impact and the initial height tends to be constant.

关键词： Brush street sweeping finite element modeling contact mechanics

Nutrimental diagnosis of avocado(Persea americana Mill.)“Haas”,soil fertility and water quality in Cuernavaca,Morelos,Mexico

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Agricultural Sciences 2013年第9期4卷 491-498页

作者： Hector Sotelo-Nava Oscar Gabriel Villegas-Torres Martha Lilia Domínguez-Patino Francisco Perdomo-Roldán Elías Hernández Castro Agustín Damián Nava Margarita Ramos García facultad de Ciencias Agropecuarias Universidad Autónoma del Estado de MorelosCuernavacaMexico facultad de Ciencias Químicas e ingeniería Universidad Autónoma del Estado de MorelosCuernavacaMexico Unidad Academica de Ciencias Agropecuarias y Ambientales Universidad Autónoma de GuerreroIgualaMexico

In two contrasting agricultural ecohabitats (agrohabitats) in the avocado production area in the municipality of Cuernavaca, Morelos, an analysis of nutrimental status, soil fertility and water quality was conducted to measure soil fertility levels and to determine the nutrimental state of the trees. The “Hass” variety avocado groves studied had an average age of 8 years;the first grove was planted in an acrisol soil (1700 to 1900 meters above mean sea level [mamsl]);the second, in an andosol soil (1200 to 1700 mamsl). In each agrohabitat, tests were performed to determine the soil’s physical and chemical characteristics. The physical and chemical characteristics of the soils of this zone differ as do the nutrimental states of the avocado trees in the two agrohabitats. The trees showed excessive concentration of Ca, Fe, S, Z and Mg. The indices of deviation from Optimal Percentage (DOP) in the two agrohabitats showed different nutrimental requirements;nevertheless, they were low and very near to zero, 14.218 and 13.350 respectively. The water used for the agricultural irrigation was low in salinity and sodium content and thus may be used for the agricultural irrigation without restrictions.

关键词： Avocado Nutrimental Imbalance Index Diagnosis Nutrimental Status Nutrients

Microscopic Characterization of Ecological Concrete Polymeric

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Microscopy Research 2014年第1期2卷 13-17页

作者： A. D. Rodríguez M. L. Domínguez R. M. Melgoza Centro de Investigación en ingeniería y Ciencias Aplicadas Universidad Autónoma del Estado de Morelos Cuernavaca México facultad de Ciencias Químicas e ingeniería Universidad Autónoma del Estado de Morelos Cuernavaca México.

The Scanning Electron Microscopy (SEM) and Optical Microscopy (OM) with integrated digital camera are techniques that are used in the present investigation, for the morphological characterization of a new composite material called “organic polymer concrete” in which microparticles added fibers and polyethylene terephthalate (PET) recycling mechanically (RM). Polymer concrete (PC) is a new composite material (MC) in the application considered as an alternative material of construction in which reinforcement particles are recycled polymers which have approximately the same dimensions in all directions. Therefore, the particles can be rods, spheres, chips and many other shapes whose appearance reasons are about 10 microns. These MC, the size, shape and distribution and the ratio and the modulus of the particles affect the properties of the material.

关键词： Polymer Concrete Polymer Blend