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Archivo Digital UPM (96,033 recursos)
This is an institutional repository providing access to the research output of the institution. Primarily contains thesis.

Materia = Química

Mostrando recursos 1 - 20 de 447

1. Clasificación de zonas en instalaciones para vehículos propulsados por GNC - Lázaro Higuera, Jaime
El presente proyecto tiene como objetivo principal el análisis de la viabilidad de estacionamiento de vehículos propulsados por gas natural comprimido (GNC) desde el punto de vista de formación de atmosferas potencialmente explosivas en los garajes subterráneos. Además se ha realizado una breve introducción sobre el GNC explicando el origen, la composición y los diferentes usos que tiene. Se ha realizado la evaluación de riesgos asociados a la utilización de vehículos propulsados por gas natural y estimación de tasas de escape en el circuito de combustible de los vehículos propulsados por GNC. Para ello se ha aplicado la normativa UNE...

2. Wettability, polarity and water absorption of Quercus ilex leaves: effect of leaf side and age - Fernandez Fernandez, Victoria; Sancho-Knapik, Domingo; Guzmán Delgado, Paula; Peguero Pina, Jose Javier; Gil Sanchez, Luis; Karabourniotis, George; Khayet, Mohamed; Fasseas, Costas; Heredia-Guerrero, José Alejandro; Heredia, Antonio; Gil Pelegrín, E.
Plant trichomes play important protective functions and may have a major influence on leaf surface wettability. With the aim of gaining insight into trichome structure, composition and function in relation to water-plant surface interactions, we analyzed the adaxial and abaxial leaf surface of Quercus ilex L. (holm oak) as model. By measuring the leaf water potential 24 h after the deposition of water drops on to abaxial and adaxial surfaces, evidence for water penetration through the upper leaf side was gained in young and mature leaves. The structure and chemical composition of the abaxial (always present) and adaxial (occurring only...

3. Probabilistic meta-analysis of risk from the exposure to Hg in artisanal gold mining communities in Colombia - Miguel García, Eduardo de; Ortega Romero, Marcelo; Gómez San Martín, Amaia; Clavijo, Diana
Colombia is one of the largest per capita mercury polluters in the world as a consequence of its artisanal gold mining activities. The severity of this problem in terms of potential health effects was evaluated by means of a probabilistic risk assessment carried out in the twelve departments (or provinces) in Colombia with the largest gold production. The two exposure pathways included in the risk assessment were inhalation of elemental Hg vapors and ingestion of fish contaminated with methyl mercury. Exposure parameters for the adult population (especially rates of fish consumption) were obtained from nation-wide surveys and concentrations of Hg...

4. Flammability properties of thermally dried sewage sludge - Fernández Áñez, María de las Nieves; Garcia Torrent, Javier; Medic Pejic, Ljiljana
The treatment and disposal of sewage sludge is becoming an urgent need whereby different technologies were developed and integrated into the waste cycle all over the world. One of the most used technologies is the thermal drying of the sludge. Thermally dried sewage sludge has interesting properties that allow its use as an alternative fuel, but also needs some consideration from the point of view of its safe operation. The aim of this study was the research on the flammability properties of sewage sludge, including ignition sensitivity, explosion severity, thermal sensitivity and thermal stability. Furthermore relationships among those properties and...

5. Characterization of spontaneous combustuion tendency of dried sewage sludge - Medic Pejic, Ljiljana; Fernández Áñez, María de las Nieves; Montenegro Mateos, Lucía; García Torrent, Javier; Ramírez Gómez, Álvaro
The general purpose of this study was the determination of the safety conditions to avoid the presence of explosive atmospheres in the wastewater industry. Eight Spanish plants located in Madrid, Barcelona and Málaga were considered and several sludge samples were taken in different seasons. The base for the assessment of the spontaneous ignition behaviour of dust accumulations is the experimental determination of the self-ignition temperature under isothermal conditions. Self-ignition temperatures at four volumes were obtained for one sample of sewage sludge, allowing their extrapolation to large storage facilities. A simple test method, based also on an isothermal study of samples,...

6. Ultrastructure of Plant Leaf Cuticles in relation to Sample Preparation as Observed by Transmission Electron Microscopy - Guzmán Delgado, Paula; Fernandez Fernandez, Victoria; Khayet, Mohamed; García, Maria Luisa; Fernández, Agustín; Gil Sanchez, Luis
The leaf cuticular ultrastructure of some plant species has been examined by transmission electron microscopy (TEM) in only few studies. Attending to the different cuticle layers and inner structure, plant cuticles have been grouped into six general morphological types. With the aim of critically examining the effect of cuticle isolation and preparation for TEM analysis on cuticular ultrastructure, adaxial leaf cuticles of blue-gum eucalypt, grey poplar, and European pear were assessed, following a membrane science approach. The embedding and staining protocols affected the ultrastructure of the cuticles analysed. The solubility parameter, surface tension, and contact angles with water of pure...

7. From plant surface to plant metabolism: the uncertain fate of foliar-applied nutrients - Fernandez Fernandez, Victoria; Brown, Patrick H.
The application of agrochemical sprays to the aerial parts of crop plants is an important agricultural practice world-wide. While variable effectiveness is often seen in response to foliar treatments, there is abundant evidence showing the beneficial effect of foliar fertilizers in terms of improving the metabolism, quality, and yields of crops. This mini-review is focused on the major bottlenecks associated with the uptake and translocation of foliar-applied nutrient solutions. A better understanding of the complex scenario surrounding the ultimate delivery of foliar-applied nutrients to sink cells and organs is essential for improving the effectiveness and performance of foliar fertilizers.

8. Molecular Dynamics Simulations of Couette flow - Martín Bautista, Juan A.; Meneghini, Julio; Theofilis, Vassilios
The first steps towards developing a continuum-molecular coupled simulations techniques are presented, for the purpose of computing macroscopic systems of confined fluids. The idea is to compute the interface wall-fluid by Molecular Dynamics simulations, where Lennard-Jones potential (and others) have been employed for the molecular interactions, so the usual non slip boundary condition is not specified. Instead, a shear rate can be imposed at the wall, which allows to obtain the properties of the wall material by means of an iterative method. The remaining fluid region will be computed by a spectral hp method. We present MD simulations of a...

9. Modeling iron-catecholates binding to NGAL protein - Gomez Casado, Cristina; Roth Walter, Franziska; Jensen Jarolim, Erika; Díaz Perales, Araceli; Fernandez Pacios, Luis
Neutrophil gelatinase associated lipocalin (NGAL) protein is attracting a great interest because of its antibacterial properties played upon modulating iron content in competition against iron acquisition processes developed by pathogenic bacteria that bind selective ferric iron chelators (siderophores). Besides its known high affinity to enterobactin, the most important siderophore, it has been recently shown that NGAL is able to bind Fe(III) coordinated by catechols. The selective binding of Fe(III)-catechol ligands to NGAL is here studied by using iron coordination structures with one, two, and three catecholate ligands. By means of a computational approach that consists of B3LYP/6-311G(d,p) quantum calculations for...

10. CO2 capture by absorption into aqueous tertiary amine solution - Clemente Jul, María del Carmen; Cebamanos, Carlos; Chen, Jian
The aim of this research is to obtain the absorption rate of CO2 into aqueous solution of N,N- di methyl ethanolamine and into aqueous solution of Triethylene diamine and to demonstrate the importance of absorption of CO2 in nowadays by discussing global warming and greenhouse effect. It is also discussed the current situation of China focusing in the latest steps this country has recently made. In the experimental part of this work, the two tertiary amine solutions will absorb CO2 in a Lewis type cell, measuring the pressure change during the reactions take place. The temperature will be between 35...

11. Heterogeneity of atmosfpheric ammonia at the landscape scale and consequences for environmental impact assessment. - Vogt, Esther; Dragosit, U.; Braban, Christine F.; Theobald, Mark Richard; Dore, Anthony; Van Dikj, N.; Sim Tang, J.; MacDonald, Chris; Murray, Scott; Rees, Robert M.; Sutton, Mark A.
We examined the consequences of the spatial heterogeneity of atmospheric ammonia (NH3) by measuring and modelling NH3 concentrations and deposition at 25 m grid resolution for a rural landscape containing intensive poultry farming, agricultural grassland, woodland and moorland. The emission pattern gave rise to a high spatial variability of modelled mean annual NH3 concentrations and dry deposition. Largest impacts were predicted for woodland patches located within the agricultural area, while larger moorland areas were at low risk, due to atmospheric dispersion, prevailing wind direction and low NH3 background. These high resolution spatial details are lost in national scale estimates at...

12. Nitrogen deposition alters nitrogen cycling and reduces soil carbon content in low-productivity semiarid Mediterranean ecosystems. - Ochoa Hueso, Raúl; Maestre, Fernando T.; Rios, Asuncion de los; Valea, Sergio; Theobald, Mark Richard; Vivanco, Marta G.; Manrique, Esteban; Bowker, Mathew A.
Anthropogenic N deposition poses a threat to European Mediterranean ecosystems. We combined data from an extant N deposition gradient (4.3–7.3 kg N ha−1 yr−1) from semiarid areas of Spain and a field experiment in central Spain to evaluate N deposition effects on soil fertility, function and cyanobacteria community. Soil organic N did not increase along the extant gradient. Nitrogen fixation decreased along existing and experimental N deposition gradients, a result possibly related to compositional shifts in soil cyanobacteria community. Net ammonification and nitrification (which dominated N-mineralization) were reduced and increased, respectively, by N fertilization, suggesting alterations in the N cycle....

13. Blends of babassu, palm kernel and coconut fame with fossil kerosene. Technical aspects of low carbon number methyl esters as a possible source for renewable jet fuel - Llamas Lois, Alberto; Canoira López, Laureano; Al-Lal Baeza, Ana María; Lapuerta, Magín
State of the Art. Process and Distillation. Fuel Characterization. Fuel Compatibility Tests

14. Blends of babassu, palm kernal and coconut mame with fossil kerosene: low carbon number methyl esters as a possible source for renewable jet fuel - Llamas Lois, Alberto; Canoira López, Laureano; Al-Lal Baeza, Ana María; Lapuerta, Magín
Three different oils: babassu, coconut and palm kernel have been transesterified with methanol. The fatty acid methyl esters (FAME) have been subjected to vacuum fractional distillation, and the low boiling point fractions have been blended with fossil kerosene at three different proportions: 5, 10 and 20% vol.

15. Aplicación de los sistemas de separación hidráulica y magnética al reciclado de los residuos de construcción y demolición - Rodríguez-Avello Sanz, Ángel; Gómez-Limón, Dulce; Peña Narciso, Christian; Fueyo, Luis
En el presente estudio se analizan las últimas técnicas aplicadas al reciclaje de los residuos de construcción y demolición (RCD), en los que además de los sistemas clásicos de estrio manual y mecánico, trituración y clasificación granulométrica se introducen los equipos de separación hidráulica (clasificadores de banda y tornillos sin fin) y los de pulsación por corriente turbulenta de acción diferencial (Jig). De igual forma los áridos reciclados ganan en calidad cuando se someten a procesos de separación magnética en los cuales las fracciones cerámicas (ladrillos) responden de forma positiva teniendo en cuenta los componentes férricos de las arcillas en...

16. Bioaccessibility of heavy metals and risk assessment in urban gardens of Madrid - Ortega Romero, Marcelo; Mingot Marcilla, Juan; García Martínez, María Jesús; Miguel García, Eduardo de; Izquierdo, Miguel; Gómez, Amaya
Human health problems and solutions. Urban gardening has spread worldwide in recent years as it enhances food security and selfsupply and promotes community integration. However urban soils are significantly enriched in trace elements relative to background levels. Exposure to the soil in urban gardens may therefore result in adverse health effects depending on the degree of contact during gardening, infant recreational activities and ingestion of vegetables grown in them. In order to evaluate this potential risk, 36 composite samples were collected from the top 20 cm of the soil of 6 urban gardens in Madrid. The aqua regia (pseudototal) and...

17. The aggressiveness of pig slurry to cement mortars - Massana Guitart, Jordi; Guerrero Bustos, Ana; Antón Fuentes, Rebeca; Garcimartin Molina, Miguel Angel; Sanchez Espinosa, Elvira
The aim was to measure the behaviour of various mortars employed in livestock media in central Spain and to analyse the aggressiveness of pig slurry to cement blended with fly ash mortars. To achieve this, mortar specimens were immersed in ponds storing pig slurry. Mortar specimens, of 40 ? 40 ? 160 mm, were made from four types of cement commonly used and recommended for rural areas. The types were a sulphate-resistant Portland cement and three cements blended in different proportions with fly ash and limestone filler. After 3, 6, 12, 24, 36, 48 and 60 months of exposure, three...

18. Propiedades de nanocompuestos de matriz termoestable con nuevos organosilicatos laminares - Calvo del Valle, Silvia; Salom Coll, Catalina; González Prolongo, Margarita; Arribas Arribas, Carmen; García del Cid, A.; Masegosa Fanego, Rosa María
En este trabajo se han preparado nanocompuestos de matriz polímero termoestable del tipo poliéster insaturado y epoxídica utilizando como refuerzo nanosilicatos laminares que se han modificado específicamente para mejorar la interacción con la matriz. En concreto se han modificado montmorillonitas con cationes orgánicos reactivos con la matriz de poliéster insaturado. Asimismo se han silanizado montmorillonitas comerciales orgánicamente modificadas con el objetivo de formar enlaces químicos con la matriz epoxídica. En ambos nanocompuestos se han estudiado las propiedades termo- mecánicas pudiendo comprobar la efectividad de los nuevos organosilicatos.

19. Preliminary approach to neutron instrument selecction at ESSB-Bilbao based on experience at ISIS molecular spectroscopy group - Vicente Bueno, Jesús Pedro de
Collaborative efforts between the Neutronics and Target Design Group at the Instituto de Fusión Nuclear and the Molecular Spectroscopy Group at the ISIS Pulsed Neutron and Muon Source date back to 2012 in the context of the ESS-Bilbao project. The rationale for these joint activities was twofold, namely: to assess the realm of applicability of the low-energy neutron source proposed by ESS-Bilbao - for details; and to explore instrument capabilities for pulsed-neutron techniques in the range 0.05-3 ms, a time range where ESS-Bilbao and ISIS could offer a significant degree of synergy and complementarity. As part of this collaboration, J.P....

20. Biodiésel de ésteres etílicos de ácidos grasos : correlación composición-propiedades - Alonso Castro, Elena
Debido a la situación energética actual, el aumento de la demanda de petróleo y precio, así como su carácter no renovable, hace necesaria la búsqueda de alternativas viables para su uso como combustible. Una de ellas es el biodiésel, ya que tiene características similares y puede ser usado como sustituto de los combustibles convencionales, sin necesidad de grandes modificaciones en el motor. Hasta ahora los estudios se habían centrado en los esteres metílicos de ácidos grasos (FAMEs) por razones meramente económicas. El proyecto tiene como objetivo el estudio de los esteres etílicos de ácidos grasos (FAEEs) para establecer una correlación...

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