CHEMISTRY, 2

Author: VALDÉS CONCA JORGE.
Year: 2004.
University: ALICANTE.
Place of defense: FACULTAD DE CIENCIAS ECONÓMICAS Y EMPRESARIALES.
Place of preparation: FACULTAD DE CIENCIAS ECONÓMICAS Y EMPRESARIALES.

Summary: The growing need to find sustainable sources of competitive advantage in the market guides the vision of the companies towards the human resources function, and within it, one of the management models that more boom is having on the international context is the management powers. This exploratory based inthe survey methodology of the case, intended to show a theoretical approach of this model through its three dimensions: the acquisition, encouragement and skills development. The work describes the evolution, approaches and the main instruments articulate this management model. Likewise, illustrated through an empirical approach to the development of the model in three major areas of activity in our country, the energy sector, financial and insurance.

Author: ARCE CEINOS ALBERTO.
Year: 2004.
University: SANTIAGO DE COMPOSTELA.
Place of defense: ESCOLA TÉCNICA SUPERIOR DE ENXEÑERÍA.
Place of preparation: ETSE.

Summary: Identify concentrations of water vapor absorbed once reached equilibrium at different water activities and 308.15 K approximately temperature of the human eye, and the properties of transport, namely diffusion coefficients of water vapor through flat plates these polymers under the same conditions. To calculate the diffusion coefficients used a model based on the Law on Fick for a flat sheet (Crank, 1975) using an equation deduced by Long and Richman (Long Richman, 1960). Data balance will be interpreted using the model developed by Flory Huggins (Flory, 1953) and also raises the objective estimation of the tendency of water molecules to be added in clusters or remain isolated from each other through the use of theories included in work and Zimm Lundberg (Lundberg, 1972; Zimm and Lundberg, 1956).

Author: LILLO BAÑULS ADELAIDA.
Year: 2004.
University: ALICANTE.
Place of defense: FACULTAD DE CIENCIAS ECONÓMICAS Y EMPRESARIALES.
Place of preparation: FACULTAD DE CIENCIAS ECONÓMICAS Y EMPRESARIALES.

Summary: This thesis examines the role of human capital as a strategic factor in competitiveness in the Spanish tourism industry. Also, there is a review of the theories of human capital and education yields as valid theoretical model. From a modeling equations income Mincerian explores relationships educacción-ingresos in the occupied tourism. Various empirical analysis estimates raised by ordinary least squares and considering the endogeneity of education, by the method of instrumental variables, determine how they valued education workers in tourist activities.

Author: FORNÉS CHAVES AMPARO.
Year: 2004.
University: AUTÓNOMA DE MADRID.
Place of defense: CBMSO-UAM.
Place of preparation: CBMSO-UAM..

Summary: The work presented in the report is a study of the relationship estructura-función the second intracellular loop of neuronal glycine transporter GL YT2. This region contains a conveyor interesting accumulation of polar residues and loaded, in the highly conserved family of neurotransmitter transporters dependent Na + and CI- call SLC6, some of them in sequence consensus phosphorylation by protein kinase C (PKC). Using a strategy directed mutagenesis, we have identified the crucial position 422 as the expression in membrane transport of glycine, dependence on voltage and balance conformacional transporter. In addition, the substitution of amino acid residues IL2 by acid eliminates the response GL YT2 the ester forbol WFP, indicating that IL2 is also involved in regulating the function of GLYT2. WFP inhibits so specific and dose-dependent and time activity conveyor, producing an effect consistent with the activation of serine kinase / threonine. Also shown that the negative regulation of GL YT2 induced LDCs can be simulated by means of activation of the signal transduction of phospholipase C (PLC), indicating that the effect of WFP is mainly due to the action of PKC. Inhibition of GL YT2 by WFP affects the transport activity of glycine as well as the expression on the surface because the kinetic parameters Km and Vmax are reduced following treatment with WFP. The ester forbol decreases in the expression of surface GL YT2 at steady state but does not alter that of the resistant mutants. This effect is mediated by a moderate increase in the membrane insertion and a large increase el1la internalization, so that the intracellular trafficking GL YT2 scrolls intracellular compartments while the resistant mutants do not reduce its expression in the membrane post to be amended in equal measure in both these mutants as internalization insertion in the plasma membrane. Finally, we have identified a waste crucial for the transport activity, voltage sensitivity and balance conformacional in the loop intracellular 3, also implicated in the regulation induced by WFP and the action of PKC. The fact that the state conformacional acquired by mutants of this waste is very similar to that shown by the mutants IL2 has helped establish the first conformational requirements of the regulation of GL YT2 induced PKC.

Author: SOLERA CARLAVILLA MARIA ELENA.
Year: 2004.
University: AUTÓNOMA DE MADRID.
Place of defense: INSTITUTO DE CERAMICA Y VIDRIO CSIC.
Place of preparation: INSTITUTO DE CERAMICA Y VIDRIO (CSIC).

Summary: The tiles for flooring and wall coverings are one of the main products in the field of ceramics and glass Spanish. The growing development of these materials has been preceded by a major effort in R + D + i One of the most interesting technological processes in recent years is the casting tape of ceramic materials because they represent an alternative method of obtaining flooring and floor coverings. The process of casting tape used in the production of materials electrocerámicos. But its translation involves the consideration of the parameters of the process and adapting it to the characteristics of glazes fisico - químicas. This thesis has focused on the use of tape casting process for the development of processes flexíbles Decoration applicable flooring and tile using crystalline glaze. First, it has studied the behavior and rheological properties of barbotinas ceramics industrial composition to be used as a basis for the process of casting. We have set conditions for stability suitable to give a slip defloculada a pseudoplastic behavior. It has established the effect of the concentration of aditívos on the properties of slip and how they affect the resulting sheet. It has studied the speed and openness of the blades cast, the process of drying, and the density and flexibílidad the resulting sheets. It has studied the evolution of the thermal sheeting enamel compared with a crystalline glaze line. Both materials sinterizan by a mechanism of viscous flow but have small differences that have been established by the curve of viscosity with temperature, which shows an increase in the value of viscosity due to the presence of desvitrificaciones. It has been found that the presence of crystalline particles in refractory enamel stabilizes these pores resulting in enamel defects in the end if its size exceeds a critical size. The elimination of these pores are conducive to the reduction in viscosity with temperature, being more effective for the removal temperatures at which crystalline phases melt within the vitreous phase. There has been characterizing the evolution of porosity with temperature techniques using Scanning Electron Microscopy, perfilometría and Atomic Force Microscopy. In studies performed with printing inks has been established that the use of processes turbines High Speed shears improved dispersion and increases performance color ink. So that has worked with barbotinas low viscosity with a higher solids content, and a reduction in the percentage pigments, inks obtained serigraph color similar to the reference. It has studied the implementation of blades cast on tape as reasons for decoration. It has been found in cooking dimensional variation of the reasons for decoration with the thickness and length of the same. It has identified the mechanism of integration of those reasons on a performance basis and enamel color such grounds. The addition of pigment to the vitreous matrix allows the decrease in viscosity to temperature consolidation enamel and thus the union with enamel base is complete. It has been found that the variation of linear color pigments in the proportion of the reasons for decoration allows for high concentrations, greater color rendition when these pigments are incorporated into the external sheet. This doctoral thesis has been protected in the patent "Flexible Process decorating ceramic products" (publication date: 16-07-2003) by CSIC and led to a trademark, Decortape.

Author: ABAD REYES JOSE ANDRES.
Year: 2004.
University: SALAMANCA.
Place of defense: FACULTAD DE FARMACIA.
Place of preparation: DEPARTAMENTO QUIMICA FARMACEUTICA.

Summary: It has conducted a survey of phytochemical Plumeria pudica Jacquin, a plant from Venezuelan flora. This study has led to the isolation and chemical characterization and espectroscópica various ligananos, flavonoids, iridoides and triterpenoides. Based on the history of the pharmacological activity of the Podofilotoxina a ciclolignano found in the plant under study, there are various derivatives of this metabolite through its structural manipulation in the laboratory. To achieve these transformations has been party podofilotoxina isolated from Podophyllum emodi because of the small amount of metabolite found in the plant studied. Various compounds have been prepared by cicloadición of Diels-Alder of acids thuriférico and epithuriférico with cilopentadieno. Additionally were obtained various pinacoles through reaction Mcmurry by coupling the podofilotoxona with different compounds carbonílicos. All compounds, both natives such as those prepared in the laboratory underwent various tests of biological activity. Many of the semi-synthetic compounds have shown a greater cytotoxicity that the substance reference podofilotoxina.

Author: Bermejo Roda María Dolores.
Year: 2004.
University: VALLADOLID.
Place of defense: Facultad de Ciencias.
Place of preparation: Facultad de Ciencias.

Summary: The oxidation aagua supercritical oxidation is the aqueous medium using oxygen or hydrogen peroxide as an oxidant stress and temperauras above the critical point of water. It is used primarily for the destruction of waste. Eficacias destruction excess of 99% can be achieved in times of residence less than 1 minute. It has been tested successfully to waste as DDTs, chemical residues low rediactividad, pharmaceuticals etc.. These deletions are due to the properties of water supèrcrítica, it behaves as an organic solvent, which organic substances are completely soluble salts while organic precipitate. The main problems of this technology are the oxidizing atmosphere and the deposition of salts. The technical solution of these problems depends on the right choice of materials and design of reactors. The reactor wall transpirable is one of these reactors. It consists of limiting the reaction chamber with a porous wall through which circulates clean water that forms a protective film against the deposition of salts, corrosive and high temperatures. In this thesis has made a pilot study of the behavior of a reactor wall transpirable a pilot scale (40 kg / h feeding). We have studied four configurations of the reactor wall transpirable, doing a pilot study of individual variables operation and also has been dealt a successful industrial waste. The last configuracón tested is a scaling, and is ready to test it at piloto-demostración (200 kg / h). There has also been a model of the reactor at steady state, using simple flow models. This model accurately describes the behavior of the reactor, and has revealed the existence of natural convection in the same. There has also been a study of the thermodynamic systems in key water oxidation supercítica, modeled feeding system isopropanol-agua-acetato sodium or sodium oleato and products, the system CO2-agua-sulfatop sodium . It has been experimentally determined equilibrium phase of these systems at the Delft University of Technology (Netherlands) under the supervision of Dr. Cor J. Peters, and these systems were modeled using the EoS of Anderko-Pitzer, developed specifically for aqueous systems at high pressures and temperatures in the presence of salts.

Author: Bustos Martín Enrique.
Year: 2004.
University: VALLADOLID.
Place of defense: FACULTAD DE CIENCIAS.
Place of preparation: Facultad de Químicas.

Summary: This dissertation is part of the lines of research that for years have been established by the Group of Theoretical Chemistry at the University of Valladolid. This work aims to cáculo and analysis of the probability of transition between electronic and vibrational states of molecules diatómicas with the use of orbital method of quantum defect in the version molecular (MQDO). The development of this work has helped confirm MQDO as a powerful tool in the calculation of spectroscopic properties of Rydberg states of molecular systems in states, both of discreo as continuous. The introduction of the part relating to nuclear movement The vibration has allowed an assessment of probabilities transition vibrónicas, which is a novel application of the methodology within the orbit of the quantum defect. Another novelty own work of this thesis has been to consider the effect of interactions between different sets of Rydberg and disruption with valence states. The result of interactions with valence states have given their properties, a highly significant development in the chronology of the method. Finally, it is likely to have established transition to the continuum states, and not only from the state funamental but also from electronically excited states. MQDO has proven to be efficient for this calculation, regardless of the degree of disturbance of the states.

Author: CIMAS SAMANIEGO ÁLVARO.
Year: 2004.
University: VALLADOLID.
Place of defense: FACULTAD DE CIENCIAS.
Place of preparation: UNIVERSIDAD DE VALENCIA.

Summary: In this Doctoral Thesis has carried out a desk study of processes possible interest in Atmospheric Chemistry, in particular the reaction of methyl radical and their halogenated with atomic nitrogen in its ground state, N (4S), as excited, N (2 D). It has carried out an exploration of the potential energy surfaces characterized chemically relevant structures, and subsequently has been conducting a kinetic analysis of the different processes using theories cinético-estadísticas. This analysis allows kinetic draw conclusions about what channels will be favored in each case. In addition, and to this end has conducted a study on the possible implications of crossing spin between different surfaces caused multiplicity of the reaction between N (4S) and N (2D), respectively with the species CH2X (X = H, F , Cl, Br).

Author: GARCÍA SERNA JUAN.
Year: 2004.
University: VALLADOLID.
Place of defense: FACULTAD DE CIENCIAS.
Place of preparation: FACULTAD DE CIENCIAS.

Summary: (English version) Throughout the world, different processes provide with a wide range of essential products for modern society, which contribute to improve without any question the human welfare. However, substantial quantities of waste and hazardous emissions have been generated due to such activities since the last century, what have caused a severe damage to the environment. In any case, this desire of pretended comfort should be tolerated if it means or carries that unacceptable damage against the environment. A green framework of products, processes and production systems, PPSs, has been developed in this work. A full development of three Green Engineering Tools PPSs-oriented is given. These tools have been successfully applied to Supercritical Fluid Technology finding it a reliable green alternative to 8 traditi 1ff8 onal processes. Firstly, a deep review in the different approaches to sustainability is presented. Green Chemistry, Green Engineering and Cradle to Cradle are defined as the three essential pillars of the green philosophy. Then, the first classification of the green technologies is given, specially emphasising in supercritical fluids and ionic liquids. Secondly, three novel key engineering tools which are useful to design, evaluate and audit PPSs from a green engineering viewpoint are presented. Green Scar is a green tool product-oriented which gives an overall idea of how cans the production process be inverted. Green Area Classification is a green tool process-oriented which divides a chemical plant in different zones according to green engineering considerations. After this analysis the plant is ranked with number between 0 and 60. Green Analysis, however, is production-oriented and provides engineers and labours with information related to how green and green-safe the operation is. A multipurpose pilot plant to study synthesis reactions in supercritical H2O, methanol and CO2 has been designed and set up. The unit will be able to operate at flowrates, pressures and temperatures up to 6 kg/h, 30.0 MPa and 400 ºC respectively. All the process parts have been made of stainless steel AISI 316. A detailed description of the unit and its operation manual is given. The behaviour of supercritical media for reaction in terms of flow pattern has been studied. An experimental method for accurate residence time measurement at high pressures has been set up. Two model green solvents, i.e. H2O and CO2 have been investigated for this purpose. A novel mathematical model for RTD based on the laminar flow model fluids has been proposed and successfully validated. The model considers that the velocity profile is not exactly parabolic but n-parabollic and takes into account the residence time. It has been shown how the proposed two-parameter model works much better than the classical models with one, two or even three parameters for both scCO2 and scH2O. A range of experiments at 10 to 30 MPa and 100 to 200 ºC at different flowrates were properly modelled. The parameter "n" increased with flowrate and decreased with pressure in all cases. Higher "n" values normally mean a more turbulent flow, while values of "n" lower than 2 mean an arrow-shaped flow. Surprisingly, values of "n" round 1.5 have been found for both scCO2 and scH2O The residence time parameter decreased potentially with the flowrate and increases almost linearly with pressure. The effect of temperature is not that evident. Some relation with Reynolds number has been found but a further study is recommended to ensure that result. In addition to this, a non-intrusive procedure to test and check high pressure continuous flow reactors analysing their defective flow pattern has been projected. The production of hydrogen via formic acid and sodium formate decomposition in water at high pressures and mild temperatures has been successfully achieved. The thermal decomposition of formic acid solutions, 2.47 mol/l, has been investigated. It produces H2, CO and CO2 and traces of CH4. Total decomposition occurs at temperatures from 300 ºC independently of the pressure. On the other hand, the thermal decomposition of sodium formate solutions, 2.47 mol/l, has been studied. It produced more than 95%mol H2; CO2 seemed to be dissolved in water and only traces of CO were measured; no CH4 was detected. Decomposition conversions of 40% were obtained at temperatures from 350 ºC. Nevertheless, temperatures close to the critical point (estimated at 375ºC) cause a dramatic precipitation of sodium carbonate and should be avoided. This procedure has been shown as a green and safe method interesting for laboratory research. A conscious screening of the behaviour of different cyclic and aromatic ketones, olefins, aldehydes and nitro-groups under hydrogenating atmosphere in sub-critical water without catalyst in a continuous flow reactor has been carried out. All the reactions were performed by using relatively dilute solutions of formic acid and sodium formate ( menor que 10% organic w/w). Conversions from 0% to 70% and high selectivity for some of the compounds were obtained. Thus, the continuous reduction of nitrobenzene was carried out from 150 200 °C and 15-30 MPa.. Reaction temperatures above 150 ºC are required to reduce the nitro group to the corresponding amine using an aqueous solution HCO2Na. A further increase in temperature from 200 to 300 ºC lead to 55% to 98% of aniline yield with selectivity over 99.9%. Surprisingly, neither cyclohexene nor benzaldehyde were reduced to the corresponding alcohols when the reaction was performed using HCO2H. This has been explained by assuming that the hydrogenation took place in the bulk fluid by a surface catalysed reaction. In this way, a well established deactivation mechanism by CO might play. That was the main difference between the formic acid or sodium formate decomposition. In other words, the lack of reactivity ketones and aldehydes when formic acid was can be explained by a surface catalyst deactivation based on CO poisoning. Moreover, it was significant that acetophenone was reduced with both feedstocks obtaining yields up to 78% at 15.6 MPa and 250 ºC with residence times as short as 19 seconds. The different reactivity of the nitro, ketone and aldehyde groups may be used to attempt a selective hydrogenation in a future work. The utilisation of the green engineering tools has been comprehensively explained thereafter using a relevant case study, i.e. terephthalic acid, TA, synthesis via partial oxidation of p-xylene in supercritical water. First of all, a g -scar analysis aided to differentiate among the different technologies for recycling and the products of each of them. Poly(ethylene-terephthalate), PET, can be considered as the main commodity produced from TA. PET is used to manufacture textile fibers, bottles and films. A mechanical treatment followed by a hydrolysis provide TA as the main product, a further oxidation will produce energy and/or other products such as benzene, phenol, etc. Then a g -Area Classification has been applied to the supercritical plant, deducing that p-xylene is not a green product and penalises the process a great deal. The use of furnaces with natural gas to reach high temperatures for the supercritical state is the reddest point of the process. As two molecules of water are coproduced in the TA synthesis, i.e. 82.2% of mass efficiency, a further waste water treatment to recover the catalyst and eliminate organic residues is necessary. This is also a red situation. In the other hand the good energetic integration and efficiency of the process fall well inside the green engineering viewpoint and the whole process is acceptable. Finally, miscellaneous technology developed during the Thesis work. The engineering conceptual design, construction and start-up of two fluidised sand bath heaters are presented. These heaters have been used in the High Pressure Pilot Plant specifically set up for this Thesis (as shown in Appendix 3B). Moreover, in order to simplify as much as possible high pressure process vessels, novel cold-closures have been developed based on the existing technology are presented in Appendix 3C. The aim was to design a simple closure to resist high pressures and at the same time able to operate at very high temperatures (more than 600 ºC).

Author: SIRVENT MASIAS GEMMA.
Year: 2004.
University: GIRONA.
Place of defense: UNIVERSIDAD DE GIRONA.
Place of preparation: UNIVERSIDAD DE GIRONA.

Summary: The development of methods of analysis of phenolic compounds is a common practice in many laboratories since the establishment of legislative measures to control the levels of these substances in the environment. The chromatography techniques represent the first choice for the determination of most organic compounds, including phenols. These, for their volatility and polarity, can be analyzed using both liquid chromatography and gas chromatography and this duality has been applied in this work. The liquid chromatography is the most commonly used technique in the determination of phenolic compounds as it does not require a prior derivatization of the analytes to improve the performance of chromatographic peaks obtained. The presence of aromatic rings in its structure makes these compounds can be easily analyzed by HPLC-UV. In Chapter 2 describes the development of a method of liquid chromatography for the determination of water in the eleven phenols present in the method 604 of the EPA. The separation of the analytes is achieved in a period of less than 30 minutes and the results obtained show that the method has a high linearity (up 50 mg L-1), good repeatabilities (RSD% less than 5%), reproducibilities. With regard to the limits of detection and quantification of the method, these are in the range of ppb for all compounds except for pentachlorophenol who are in the range of ppm. In most methods are identification of organic pollutants is necessary to introduce stages of the analytes preconcentration prior to detection because these are levels of cup and chromatography techniques are often not sufficiently sensitive to detect these levels. The solid phase extraction is, in recent years, more preconcentration technique applied by its simplicity and simply by the large number of sound stages available. The structure of the aromatic phenolic compounds makes sorbents that provide the best results in the solid phase extraction of these substances are having a polymeric structure containing aromatic parts, as they allow the establishment of interactions between type-phenols and the solid phase. The introduction of hydrophilic groups in polymers and the use of sorbents with high surface area improves the efficiency of the extraction of polar compounds such as phenols. In this report has evaluated the effectiveness of solid phases with different characteristics, a polymer matrix containing funcionalizaciones type carbonílico (Spe-ed Advanta), a polymer divinilbenceno and N-vinilpirrolidona (Oasis HLB), a phase of polystyrene and divinibenceno (Bakerbond SDAb-1) and a silica matrix chain C18. Of all these, which have provided better results in the extraction of phenolic compounds and preconcentration sorbents are the polymeric matrix and especially those where the structure contains polar groups. The extraction rates obtained with the polymer phases are generally much higher than those achieved with the matrix C18 for phenols more polar (phenol, 4-nitrofenol and 2-clorfenol). For the sorbent Spe-ed Advanta has identified the optimal conditions for flow, pH and elution for use in the extraction and preconcentration of eleven phenolic compounds present in the method 604 of the EPA (chapter 29. Flows sample exceeding 5 mL . min-1, pH values equal to or less than 2 units and eluciones made 2mL of acetonitrile have yielded recoveries of analiltos more than 70% to work with volumes of 100 ml to 1 L of samples, and levels of concentration 0.5 to 10 ug 8. L-1. Ace 1ff8 imismo has been used sorbent Spe-ed Advanta in the monitoring of different volumes of natural water fortified with the analytes and there have been previous recoveries quantitative except to work with volumes of a liter sample. In this case shows that the high percentage of humic acids and fúlvicos present in the sample (oxidability value of 58.1 mg.L-1) leads to the partial saturation of the cartridge and, consequently, a decrease of up to 50 % recoveries of phenolic compounds. In the case of gas chromatography applied to the analysis of phenols is required for a stage prior to the detection derivatization to improve behavior and chromatographic resolution on the separation. group hidróxilo phenolic suffers adsorption on the surface active column chromatographic peaks resulting in asymmetric and very tail. also is capable of forming links bridge hydrogen intermoleculares and lead to aggregates of molecules that can hardly be volatizados. acetylation and sililación tested as methods derivatization of phenols prior to GC-MS analysis (Chapter 3). acetylation with anhydrous acetic and basic means is a relatively long process because it requires the passage of derivatives, once formed, half organic, through a liquid-liquid extraction. For this reason and the fact that the peaks of the phenolic compounds sililados present a formamás gausiana, has chosen to use the sililación as methods derivatization of the analytes. As agents sililantes have been assessed three commercial reagents containing a half trifluroacetamina (MTBSTFA, MSTFA and BSTFA) and has been compared to its effectiveness in derivatization ten phenolic compounds on the resolution provided for similar compounds contiempos retention, as well as in the presence of other substances in the reaction medium as acetone, methanol or water. The results show that in general, the presence of trace amounts of methanol and water causes a reduction in yield dela reaction sililación of phenolic compounds for the three reagents, because they contain substances groups competing with phenols by consumption derivatizante and, in addition, are capable of producing the hydrolysis of derivatives once trained. reagents Of the three, N-metildimetilsilitrifluoacetamida (MSTFA) has proved to be the most suitable to carry out the derivatization of the analytes and the optimal conditions for derivatization it has been determined using this reagent. Starting from a factorial design type has been able to verify that variables such as the volume of reagent derivatizante, temperature or time parameters are not derivatization causing a significant change in the yield of the sililación of phenols with MSTFA, although it is necessary to use a volume in excess of reagent to ensure stability delos derivatives formed. time derivatization Nor is a critical parameter because this takes place immediately to contact the analytes and agent derivatizante inside the inyectro of chromatograph, with yields similar to working with injection temperatures between 200 and 300 ° C. The gas chromatography applied to the analysis of phenols, once derivatizados, is a technique that provides very sensitive, especially when using mass spectrometry as detection systems. Employing technique has been developed is a method for determining bromofenoles and composite fisbenólicos water that provides a comprehensive range of linearity, provides limits of quantification of analítos of order of the few ug.L-1 and allows identification of chromatographic peaks with a high percentage of certainty. addition, the acomplamiento of gas chromatography to a tandem mass spectrometry makes it possible to reduce the noise caused by the presence interference in anállisis of complex samples such as those from a waste water treatment plant. Analysis of soil samples requires removal of the analytes through methods that often are drastic and less selective, which may result in coextraigan a large number of interferences in conjunction with the compound of interest. Chapter 4 have exploited the properties presented by acid phenolic compounds to develop a method of extracting the eleven phenols included in the method 604 of the EPA through alkalis , which allows easily extract phenols as fenolato. drawback of this collection is that it also carries substances húmicas and fúlvlicas present in the soil, which make it difficult detection of analytes by liquid chromatography without a pre-clean - up of the extracts. sorbent polymeric Bakerbond SDB-1, matrix poliestireno-divinilbenceno, has proven effective in the purification and concentration of phenols in soil extracts because it is capable of reducing much of the initial band delos caused chromatograms the presence of substances húmicas and fúlvicas, which hampers the quantification of the analytes with lower retention times. Unlike the solid phase evaluated in Chapter 2 (Spe-ed Advanta), the cartridge Bekerbond SDB-1 does not require a acidification of excerpts previal the SPE process for obtaining quantitative recoveries of you analytes. method overall (alkaline soil extraction and clean and preconcentration by SPE with the cartridge Bakerbond SDB-1) has been applied to analyze different portions of 1 -10 grams of soil fortified levels 1-20 ug.g-1 with phenols. In all cases have been obtained recoveries of greater than 80%, although it notes that these decreases with increasing the amount of sample. A increasing the amount of soil removed involves an increase in the concentrations of humic acids and fúlvicos coextraídos, l which can saturate partly as the solid phase and cause a decrease in the retention of analítos. extraction method and has been validated by preconcentration comparison of the results with those obtained with the method official 3540 of the EPA (Soxhlet extraction) and analyzing soil certified reference (CRM112-100) containing eight of the eleven phenols studied at concentration levels between 2 and 6 ug. g-1. soil analysis is complex because the extraction methods tend to be rather selective and drag interference of the matrix which hinder the detection end of the analytes. In the case of phenolic compounds, as well as other types of substances, should be considered an added problem is that these compounds may suffer degradation or adsorption phenomena in the ground. These processes that occur within the soil has been witnessed by the application of two different methodologies defense, one where the extraction takes place immediately after fortification (spot spiking), and another in which, once fortification and delsuelo before giving way to their extraction, it leaves a time to interact with pollutants matrix solid (slurry spiking). recoveries that have obtendio from the second method (slurry spiking) have proven to be up to 60% lower than those achieved through spot spiking, which shows that, during the process of evaporation solvent, phenols suffer transformations that make can not be detected in its original form. These changes include irreversible adsorption on any of the components of soil, organic matter and mainly clay, chemical degradation by the action of enzymes and metallic oxides or biological degradation by the presence of microorganisms, but the specific weight of each 8 of this b93 s phenomena depends largely on each floor concrete. It has been found that the degradation of phenols takes place over a long period of time, because that when making withdrawals from the same sample in a time interval of one month it has been observed that the values obtained over time diminishing. These differences are greater when the samples are kept to 4 ° C regarding -21 ° C. This fact we draw that, in analyzing soil samples contaminated with phenol compounds, it is necessary to keep them frozen if they want to keep pollution levels similar to those existing at the time of sampling. finally has studied the adsorption properties of four compounds phenolic (phenol, 2-clorofenol, 2-nitrofenol and 2,4-diclorofenol) in six different characteristics of soils (Chapter 5). determine soil properties and the phenolic compounds that have the most influence on the adsorption capacity of these substances in soils is useful in predicting their destiny once discharged into the natural environment: If remain adsorbed in the soil or whether they will be more likely to achieve the aqueous streams. have been identified adsorption isotherms of the four individual phenols in the six evaluated soils, which have been adjusted to models Freundilich, Langmuir and the Law of Henry. phenol shows, in general, a different behavior than other compounds, with H-type isotherms obtained for this compound in the Most soils, while 2CP, 2NP and 24dCP presented isotherm type L. With regard to the characteristics of the analytes, the increase in the capacities of adsorption of phenols is directly proportional to an increase in hydrophobicity of these compounds or even aumeneto in the number of chlorine atoms in the molecules chlorinated. A principal component analysis has identified what are the characteristics of soil that have more influence in the processes of adsorption of phenolic compounds. Percentage of soil organic matter is one of the parameters that most influence on the adsorption of phenols in soils are pH of the latter and its contents and type of clay fraction.

Author: Castillo Andreo Esther.
Year: 2004.
University: POMPEU FABRA.
Place of defense: Dep. Ciencias Experimentales y de la Salud.
Place of preparation: Dep. Ciencias Experimentales y de la Salud.

Summary: The reactive oxygen species (ROS), superoxide (O2o-), hydrogen peroxide (H2O2), and hydroxyl radical (OHo) are generated from the partial reduction of molecular oxygen during metabolic processes like breathing or after exposure certain environmental agents such as UV radiation. These ROS can react with biomolecules such as lipids, proteins and DNA and inactivate its role, so that the cells have developed enzymatic activities that are responsible for maintaining levels no-tóxicos of these oxidants. It is called oxidative stress to the situation where there is an increase in the concentration of intracellular ROS as a result of an increase in the generation, or a decrease in the degradation of the same. In response to oxidative stress, the cell signaling pathways active and specific transcription factors that trigger the expression of antioxidant proteins involved in intracellular redox levels restore and repair the damage caused by these oxidants. The yeast Schizosaccharomyces pombe is an ideal model organism for the study of responses to oxidative stress in eukaryotic cells because it has special sensors to oxidative stress as the transcription factor Pap1 (pombe AP-1-like) routes and comprehensive response to stress, such as those described in mammalian cells, which are activated by different types of stress. In the center of this route comprehensive response to stress is the MAPK (Mitogen-activated protein kinase) Sty1. The transcription factor Pap1, cytoplasmic localization of basal, accumulates in the nucleus in response to oxidative stress. This shift in subcellular localization is due to inhibition of nuclear export dependent Crm1, although unaware of the molecular mechanism used by this transcription factor for sensar and respond to oxidants such as H2O2 and dietilmaleto (DEM). The results show that H2O2 oxidizes in a reversible two cysteine residues of Pap1 inducing probably the formation of a bridge disulfide intramolecular, while DEM acts as an alkylating agent that alters irreversibly cysteine residues domain C - terminal Pap1. The gene coding for transcription factor Pap1 was originally isolated as a gene that, in large numbers of copies, giving the cells a phenotype of resistance to certain drugs such as estaurosporina. This is because, after accumulate in the nucleus in response to oxidative stress, Pap1 activate the transcription of genes involved in the antioxidant response in the resistance multidrogas. All those genes, like pap1 were identified by their involvement in the resistance multidrogas, encoding proteins that regulate the activity of transcription factor Pap1. Hba1 was the only gene associated with resistance to multidrogas, whose gene product, a protein with a mastery of a union Ran (Ran-binding domain), Hba1, had not been linked with the activity of Pap1. One of the goals of my experimental work was to determine whether Hba1 had a role in regulating the activity of Pap1. Our results indicate that the protein Hba1, located in the nucleoplasma of the cell involved in the nuclear export mediated Crm1 of certain proteins such as transcription factor Pap1 and MAPK Sty1, but not others such as protein PKI. Therefore, the loss of function Hba1, deletion or overexpression of the gene hba1, induce nuclear localization constituting Pap1 and Sty1 in the absence of stress. This location nuclear Pap1 is sufficient for the transcriptional activation of target genes. Therefore, the resistance phenotype increased to multidrogas of the strains under which it has lost the activity of the protein Hba1, is due to the accumulation of Pap1 in the nucleus in a position to no-estrés

Author: LOPEZ CUDERO ANA.
Year: 2004.
University: AUTÓNOMA DE MADRID.
Place of defense: INSTITUTO DE QUIMICA FISICA ROCASOLANO.
Place of preparation: INSTITUTO DE QUIMICA FISICA ROCASOLANO.

Summary: In this thesis are combining classical electrochemical techniques such as voltametría cyclical, as with other infrared spectroscopy with Fourier transform, the tunneling microscopy or second-harmonic generation in order to study the variations in the coating function the potential of admission and explain the existence of pre-pico in voltamogramas of stripping CO. In summary: We have identified the coating CO depending on the potential for admission using voltametría cyclic combined with the method of moving freight by CO and accurate correction of double layer for basal surfaces of Pt, as well as polycrystalline Pt. - We have studied for the Pt (111) and Pt (100) variation of the IR bands depending on the potential, and potential constant, depending on the degree of saturation of CO in the dissolution, Differential spectra taken at intervals constant as time is saturated with CO dissolution, or CO is removed from the same bubbling nitrogen. The main conclusions to be drawn from this argument are as follows:-In the case of Pt (111) and Pt (100) have been able to demonstrate that the coating maximum CO (equal to 0.75 ML, in the case of Pt (111), but unknown in the case of Pt (100) could be achieved only in the presence of CO in solution, while dissolutions free CO, we quantified the maximum coating is 0.68 for Pt (111) and 0.78 for Pt (100). has been seen through the evolution of CO bands in FTIRS that there are the following balances reversible: Pt (111) -CO (P = 0.68) + COdis Pt (111) - P (P = 0.75) Pt (100) -CO (P = 0, 78) + COdis Pt (100) -CO (P = max) - For all surfaces, coating maximum CO in the absence of CO at dissolution, is reached only if the potential for admission (potential at the electrode is maintained while burbujea CO) is in the area of adsorption / desorption of hydrogen (E 0.30). however, the surface halla totally blocked for the adsorption of hydrogen to 0.50 V in Pt (111), 0.40 V in Pt (100) and 0.45 V at Pt (110), indicating that different structures of the adcapa CO they are able to completely block the surface. Therefore, the pre-pico on Pt (111) and Pt (100) can be assigned to the partial oxidation of adcapa coating maximum CO, formed when Ea 0.30 V. This oxidation potential low correspond to the reaction, through a mechanism Langmuir-Hinshelwood between oxygen species formed on the steps and: (i) molecules of CO adsorbed on these steps, (ii) the molecules of CO adsorbed on the terraces, but which spread slowly to the treads. Peak's main HP stripping begins nucleation occurs when oxygen species also on the terraces, accelerating the process. For E> 0,30-0,35 V, not there pre-pico because the molecules which originate already oxidized before recording the VC-stripping. however, most of the molecules of adcapa unmanned oxidized, probably because its spread to the stairs, once formed the adcapa with less coating to these potential admission, it is slow. Oxidation of these molecules requires nucleation of oxygen species in the terraces, which can only happen to more positive potentials. different behavior pre-pico on surfaces (110 ) with respect to the (111) and (100) can be explained by the difference in the rate of diffusion of molecules of CO to the steps, in both directions of the unit cell characteristic of this area. raised We have two scenarios for the absence of pre-pico and explanation of the appearance of the main peak, which consists of a main peak with a shoulder greater potential to: (i) the topography of the surface to prevent a sufficient number of molecules of CO is disseminated to the steps a sob 8 repotenc 534 iales low, or on the contrary, (ii) a large number of molecules is capable of spreading rapidly along the rows of atoms Pt, in the direction most favored energy potential and oxidized to minors, becoming the pre-pico in the main peak of voltamograma, with a greater potential to shoulder, for the molecules to be spread across the valleys, in the right direction with a greater potential barrier. Our data do not allow us to choose between these two possibilities, although it is obvious that the spread is slow on the surface of the Pt (110), as they are required speeds of minors for logar the sweep complete oxidation of adcapa CO.

Author: GOMEZ PRIETO MARIA SALUD.
Year: 2004.
University: AUTÓNOMA DE MADRID.
Place of defense: UNIVERSIDAD AUTONOMA.
Place of preparation: UNIVERSIDAD AUTONOMA DE MADRID.

Summary: It is well established that the consumption of fruit and vegetables is beneficial to health due mainly to the action of different plant components that reduce the chances of suffering, among other diseases, certain cancers and heart disease. Among the various bioactive compounds present in plant foods, the group of carotenoids has been one of the most studied long known for its activity as provitamin A. There are also some carotenoids not acting as provitamin A, and that however, their consumption is of special interest because of their high antioxidant activity, is the case of licopeno, carotenoide majority of the tomato. On the other hand, the Spanish production of fruit and vegetables is one of the most important in the European Union. Specifically, Spain is the second largest producer of tomato reaching 4 million tons in the year 2004. Unfortunately, the cultivation of tomatoes annually generates significant amounts of surplus products and that there is no opening in the market. At the time of initiating this study, among the possible options for treatment of this waste, there was no contemplate obtaining the nutritional compounds of interest, not by considering both the economic potential that would obtain the bioactive compound high value added. In this context, it would be very helpful to implement these vegetable waste extraction techniques that would allow extract such substances. It was also known that the nutritional compounds of interest in plants, and more specifically carotenoids are likely to rust when they are exposed to the action of organic solvents, air or light. The occurrence of these phenomena is inadvisable because it is proven that the biological activity of these pigments depends on the degree of oxidadción and the geometric configuration. In addition, withdrawals conventional involve the use of large quantities of organic solvents, some of which have high prices, are pollutants and are potentially dangerous. The disadvantages posed by extracting these compounds using dilventes organic highlight the need for new techniques to facilitate the extraction work, minimize losses and degradation of solutes and are respectful of the environment. In this regard, the implementation of carbon dioxide supercritical conditions in the extraction of bioactive compounds present in these surpluses would provide an adequate alternative to conventional extraction methods because, among other reasons, to the ability to operate at low temperatures and in the absence organic solvents, conditions that would reduce the possibility of oxidation and isomerization of the compounds of interest, while avoiding the use of polluting products. In response to the needs raised, the main objective of this study was to examine the feasibility of extraction of bioactive compounds from agricultural surpluses, using a technology with low environmental impact: the extraction with carbon dioxide supercritical conditions. To that end, most of the survey was conducted using as a raw material agricultural surpluses tomato, and is therefore considered mainly extraction of bioactive compound of greatest interest in this matrix, in this case the carotenoid pigments, and more specifically , obtaining licopeno. This involved: To determine the bioactive compounds present in extracts from tomato using analytical techniques that provide data acceptable both quantitatively and qualitatively (HPLC-PDA, HPLC-MS). To conduct the study of the solubility of tomato carotenoids in supercritical carbon dioxide, using an extraction equipment at the analytical and describing the behavior d 8 and solubi ed9 bility of the major carotenoids found in the extracts applying theoretical models solubility. It was also anlizó the effect of the matrix in the extraction of carotenoids with supercritical carbon dioxide using different parent plant. Studying the possible splitting of the various carotenoids present in the samples using a tomato plant extraction at semipreparativa, evaluating the effect of different experimental variables involved in the separation of these compounds and optimizing to obtain splitting more interesting. Consider at the same time the experimental conditions provide the best recoveries of the compounds studied. Use a plant semipreparativa extraction with supercritical carbon dioxide to implement working conditions selected samples of different varieties of tomatoes, as well as different parts of this (whole tomatoes, skin and pulp), so that an assessment can be obtained from fractionation and yields achieved with actual samples of agricultural surpluses. It also analyzed the isomerization of the final products obtained using analytical techniques that provided information about the geometry of structural composites (NMR). Based on the results obtained during this work, it was possible to establish the following conclusions: 1. The use of carbon dioxide in supercritical conditions can be drawn from carotenoids and other bioactive compounds as vitamin E, alpha and beta amirina present in the fruit of the tomato. 2. Carotenoids taste exhibited entre-sí different solubility in supercritical carbon dioxide. 3. Theoretical models solubility of Chrastil and Del Valle and Aguilera, adequately described the solubility of carotenoids present in tomatoes as other parent plant, obtaining good results correlation between theoretical and experimental data. 4. Overall, the increase in temperature extraction favored the solubilization of carotenes in parent plant, however, was the density of carbon dioxide which determined the start of each extraction carotenoide and therefore was variable pilot most influenced the fractionation of these compounds. 5. The optimization variables work involved in the process of extraction with supercritical carbon dioxide separation allowed on a selective components extracted from the fruit of the tomato, so it was possible to obtain two fractions, one formed by todo-trans-licopeno in crystalline form with a high degree of purity and the other composed of the other carotenoids and other substances of nutritional interest. 6. Therefore, the application of extraction with supercritical carbon dioxide represents an alternative to the use of surplus agricultural tomato that does not require the use of organic solvents and contaminants represents, in this way, an option for minimal environmental impact waste management.

Author: NUÑEZ MORALES VERONICA.
Year: 2004.
University: AUTÓNOMA DE MADRID.
Place of defense: FACULTAD DE CIENCIAS.
Place of preparation: FACULTAD DE CIENCIAS.

Summary: In this work doctoral thesis presents the changes in the composition phenolic and the color of the skins of grapes, Vitis vinifera L. Graciano (Spanish variety of small size but highly appreciated), Tempranillo (Spain variety par excellence) and Cabernet Sauvignon (French variety known and grown at the international level) on dates close to the technological maturity of the grape. The grapes came from the station Viticulture and Enology of Navarre (EVENA, Olite) and occurred approximately every 3 days in a period of 10 days before and 10 days after the technological maturity of the vintages of 2000, 2001 and 2002. It was determined by the total phenolic content methods espectrofotométricos and composition antociánica mediente HPLC / DDA and HPLC / ESI-MS and chromatic features by calculating indices color. In addition two methodologies were developed by normal phase HPLC / ESI-MS and MALDI-TOF to determine the composition monomer and oligomérica of flavan-3-oles of nuggets. We provide new information on the identification of compounds antociánicos and flavánicos of grapes in general. We found that the distribution of anthocyanins in the samples collected in the technological maturity (vintage) is maintained in upcoming dates for each of the varieties studied, enabling characterization varietal regardless of the year of survey and sampling date. The influence of varietal character was higher in the composition of the skins antociánica that the procianidinas of nuggets, where the characteristics of the year have added significance. In upcoming dates to the technological maturity, the total phenolic content, the content in anthocyanins and indices color variations presented more or less pronounced depending on the grape variety and climatic conditions recorded 24 hours prior to sampling. In most cases the technological maturity date established by the cellar corresponds to the highest values in the variables measured.

Author: SGARLATA CECILIA LORENA.
Year: 2004.
University: AUTÓNOMA DE MADRID.
Place of defense: CENTRO NACIONAL DE BIOTECNOLOGIA.
Place of preparation: CENTRO NACIONAL DE BIOTECNOLOGIA.

Summary: The fungus fitopatógeno U.maydis is the causative agent of the disease from coal corn. The life cycle of this body consists of two phases: a phase saprofítica where the fungus grows com uan levaura and uan stage of the parasite after it has entered the plant and where to grow as a filamentous fungus. The infection process is determined porl ap resencia two sexual loci: a and b. The first encode proteins belonging to a pheromone receptor system and the second two proteins that form a heterodímero possessing role of transcription factor and is related to the development pathogenic. When two haploid cells sexually comaptibles is necuentran on the surface of the plant will merge their cytoplasm but not their nuclei mediated structures tubes called conjugation. Once this event occurred b genes are activated and will lead to the formation of uan new structure called filament infective or dicarionte that will be able to penetrate the plant. Because this series of events involving a cmabio the type of crecimineto (from yeast to filamentous) the focus of this study was detemrinar the realción enter the cell cycle and these processes. This menra explored the main regualdores the transition G2 / M in eukaryotic cells (the kinase Wee1 and phosphatase Cdc25) and their effects on the kinase Cdk1. It was further established the relationship between the state of phosphorylation of Cdk1 and pathogenesis. Finally it was determined that durnate training filament infective occurs uan stop cycle in the phase G2 cell cycle and that this is necessary to stop him pathogenic development.

Author: SICILIA APARICIO MARIA DEL CARMEN.
Year: 2004.
University: AUTÓNOMA DE MADRID.
Place of defense: FACULTAD DE CIENCIAS.
Place of preparation: FACULTAD DE CIENCIAS.

Summary: This paper presents a theoretical and mechanistic study of the protonación an organic base (pyridine), clusters of water. The problem is considered in terms of energy and thermodynamics. In addition, it is considered the variation of the energy of Gibbs' delta'G, and pKa. It identifies the TS's and the IRC's process protonación for the case of pyr-5 (H2O). To explicitly represent the transfer protónica and analyze the stabilization of ionic species formed, it is considered the interaction of pyridine with clusters of water, which increases their size. Considered: pyr-nH2O (n = 1-5). It identifies the structural characteristics of the pyridine desprotonada and protonada in different complexes. In addition, he examines the variation of the properties enlazantes, like the stability of the energy complex depending on the number of water molecules. Also considering the vibration modes in the complex, in order to clarify the mechanism that involves the transfer protónica. The mechanism protonación in aqueous solution may be considered complex with clusters of water increase in size. This kind of study evidenciaría differences that arise when the protonación made from the gap until the dissolution. The starting point is to know how many water molecules are involved in the process. The protonación of pyridine in a cluster of No water molecules is described in the following balance: pyr + nH2O pyr-H + Â OH-Â (n-1) H2O The equation shows a pyridine molecule hydrated or solvatada, that protona by a hydrogen abstraction from the water molecule. The result is a hydrated cation (pyr-H +) to be offset by a cargo hydroxyl group (OH). In the complex solvated and protonados, with n = 1, 2 and 3, clusters of water form a single ring with pyridine, where the water molecules are joined by hydrogen bond. Clusters of n> 3 form two rings. One of them involves the pyridine, while the other is made up exclusively of water molecules. Based on the theory AIM noted that the protonación, the H cluster abstracted water, it is attacked by covalentemente N piridínico. It is found that the hydroxyl group thus generated in the cluster of water, interacts strongly with the H of C ortho respect to N piridínico. The interaction is so strong that the H is abstracted from C to the OH. It is, thus, a covalent bond between OH The results suggest that protonación aqueous mechanism involves a concerted transfer protónica involving rings of water molecules in the complex. There is only one transfer protónica concert to the complex with n = 1, 2 and 3, there are two different mechanisms for the complex with n = 4 and 5. The calculation of the reaction paths for protonación in the five complexes considered, identifies a TS for clusters of n = 1 to 3, and two TS's for n = 4 and 5, plus a new structure desprotonada (solvatada) in clusters of the latter. Using the index of similarity Carbó is that the TS's are closer to the ways in which the P S. In addition, it decreases the activation energy of the protonación, and the yield of the reaction increases with the number of water molecules. Considering the variation between Gibbs energy forms SyP more stable, is that the protonación needs four water molecules to be a spontaneous process. In particular, and in spite of the difference with an aqueous solution, it requires five water molecules to obtain a pKa value of the same order of magnitude as that determined for pyridine in water.

Author: DE LA ESCOSURA NAVAZO ANDRES.
Year: 2004.
University: AUTÓNOMA DE MADRID.
Place of defense: DEPARTAMENTO DE QUIMICA ORGANICA.
Place of preparation: DPTO DE QUIMICA ORGANICA DE LA UNIVERSIDAD AUTONOMA DE MADRID.

Author: PEREZ CABERO MONICA.
Year: 2004.
University: AUTÓNOMA DE MADRID.
Place of defense: INSTITUTO DE CATALISIS Y PETROLEOQUIMICA (CSIC).
Place of preparation: INSTITUTO DE CATALISIS Y PETROLEOQUIMICA (CSIC).

Summary: In the last decade, the discovery of carbon nanotubes (CNTs) has resulted in the development of a large number of studies to determine its properties and applications [1]. However, there are quite a few aspects to be clarified about the chemical mechanism of their formation and also about their growth kinetics [2]. The theory of growth overwhelmingly accepted for carbon filaments, considered an early stage of decomposition of hydrocarbon on the metal, and the dissolution and diffusion of carbon through the metal particle. This phase is called nucleation of the filaments [3]. Below is the growth phase, when the carbon starts to precipitate forming the filament [2-7]. Anyway there is a lot of controversy in the literature about the driving force generated by the diffusion of carbon through the metal particle. The work has been presented at this Doctoral Thesis deals with various aspects of the synthesis of carbon nanotubes. First has done extensive literature review on the history of carbon nanotubes, its discovery and synthesis methods widely used. Within these synthesis methods developed deeper description of the method by catalytic decomposition of hydrocarbons (CVD). It is with special attention to the use of iron catalysts supported, justifying the benefits of its use, compared with cobalt or nickel, as well as the use of acetylene as a source of carbon. In another section provides a thorough review of studies of the mechanisms of growth of carbon nanotubes, considering the kinetic and thermodynamic aspects, considering the role of catalyst and active phases of the same during the nucleation of filaments and commenting on the effect of the parameters of the reaction (temperature reaction, the concentration of reactive gases, etc.) in the final characteristics of nanotubes synthesized. To study the kinetics and mechanisms of growth of the CNTs have prepared a number of iron catalysts supported on silica. There were several precursors used as nitrate (1 and 5% by weight), ftalocianina (1%) and pentacarbonilo (1%). All catalysts were characterized by chemical analysis, temperature programmed reduction (TPR), X-ray diffraction (XRD), infrared spectroscopy of quimisorción CO microcalorimetría of quimisorción CO and spectroscopy MÃ ¶ ssbauer. So you can record on a continuous basis, the concentration and speed of formation of the carbon deposited species. It has studied the influence of the composition of the atmosphere reaction (PH2, PC2H2) and the temperature of the reaction (600-800Â ° C) on the rate of formation of coal and on the morphology of the carbonaceous deposits obtained with the catalysts prepared . With the data collected has developed a mathematical model that describes the synthesis of CNTs, and it has become clear as the kinetics of the process will be mainly influenced by the concentration of acetylene in the reactive mixture and the temperature of the reaction. The carbonaceous material obtained have been characterized by transmission electron microscopy (TEM), to confirm the presence of CNTs, and has seen how the product produced at low temperatures are more amorphous, while preparations to higher temperatures are mainly carbon nanotubes very grafitizados. By spectroscopy MÃ ¶ ssbauer has studied the presence and contribution phases type of iron carbides. Thus, we noticed the presence of a single iron carbide type cementi 8 ta, and ae9 has seen clearly how their contribution increases with the temperature of the reaction, confirming the role of this kind as an intermediary for the reaction of formation of nanotubes carbon. To study the mechanism of growth of the CNTs, in addition to studying the existence of intermediate stages type carbides by MÃ ¶ ssbauer, we have conducted several timely synthesis reactions with acetylene enriched 13C, in order to study the presence of these species carbide through MAS-RMN of C-13. The aim of these studies was to get a signal from these species NMR carbide, and has finally achieved detect that signal and has shown more clearly the role of cementita as carbide intermediate in the formation of synthesis of carbon nanotubes. Finally, with all the data collected about the best reaction conditions for the synthesis of CNTs cigars in high yields, we have designed a fluidized bed reactor for the synthesis of these wide gram. We have studied the morphological properties of the material obtained, and assessed their ability to store hydrogen in a high-pressure volumetric team, as one of the most interesting applications that have been running for the CNTs is the retention of gas. These studies were carried out comparatively with other carbonaceous materials, and finally check how carbonaceous materials in general and carbon nanotubes in particular, are not suitable for storing hydrogen in large quantities. [1] Ajayan, PM, Chem. REV., 99 (1999) 1787. [2] KP De Jong and J. W. Geus, Catal. Rev.-Sci and Eng., 42 (2000) 481. [3] Baker, RTK, Harris, PS, Thomas, RB And Waite, R. J., J. Catal. 30, 86 (1973). 4] I. Alstrup and MT Tavares; J. Catal., 135 (1992) 147; ibid, J. Catal., 139 (1993) 513. [5] JW Snoeck, GF Froment and M. Fowles, J. Catal., 169, (1997) 240; ibid, J. Catal., 169 (1997) 250. [6] J. R. Rostrup-Nielsen, Stud. Surf. Sci. And Catal., 139 (2001) 1. [7] I. Alstrup, J. Catal., 109 (1988) 241.

Author: JARAMILLO CARMONA SARA.
Year: 2004.
University: SEVILLA.
Place of defense: DEPARTAMENTO DE INGENIERIA QUIMICA.
Place of preparation: DEPARTAMENTO DE INGENIERIA QUIMICA. FACULTAD DE QUIMICA. UNIVERSIDAD DE SEVILLA.

Summary: Spain is the leading producer of asparagus within the European Union, though the Andalusia region more hectares dedeica to this crop. This product is easy and inexpensive growing and highly appreciated in many European and American countries where the white asparagus is almost unknown. The objectives of the thesis were: 1Â º. To characterize the mechanical properties of different types of asparagus. 2 Â °. To determine the phenolic composition of the cell wall. 3 Â °. Studying the role of peroxidaxas on polymeric compound on the wall. As a general conclusion is suggested that the process of hardening of asparagus is due to a process of intersecting phenolic between polysaccharides of the cell wall Primary