PHYSICAL CHEMISTRY (2)

Author: VÁZQUEZ MELIS HÉCTOR.
Year: 2005.
University: AUTÓNOMA DE MADRID [www.uam.es].
Place of defense: FACULTAD DE CIENCIAS.
Place of preparation: FÍSICA TEÓRICA DE LA MATERIA CONDENSADA.

Author: VILLANUEVA GARCIA FLORENTINA.
Year: 2006.
University: CASTILLA-LA MANCHA [www.uclm.es].
Place of defense: FACULTAD DE CIENCIAS QUIMICAS.
Place of preparation: UNIVERSIDAD DE CASTILLA LA MANCHA.

Summary: In the low troposphere, volatile organic compounds (VOCs) emitted into the atmosphere suffer degradation processes such as fotólisis and reactions of oxidation. In the latter case, photochemical reactions are initiated by the attack on the OH radical of VOCs during the day, the radical NO3 overnight and ozone both by day and at night there is also a contribution of atoms in the Cl coastal areas where they are generated from sea salt aerosols forming species fotolizables as Cl2, ClNO, ClNO2. Since many organic compounds are constant speed wing reaction with atoms of Cl? 102 higher than for the reaction with OH radicals, indicates that the reactions with Cl atoms in the marine boundary layer, and also in the coastal regions could be significant. The furans are hetero aromatic compounds that are emitted into the atmosphere as the primary anthropogenic pollutants from the combustion of fossil fuels, garbage, plants and especially from the burning of biomass. These compounds are also secondary pollutants generated from the fotooxidación hydrocarbon structure CH2 = CH-CR1 = CHR2 as 1,3-Butadiene, isoprene and 1,3-pentadieno and aromatic compounds such as toluene and o-xyleno. Thus, in this thesis has been studied atmospheric oxidation of furan and some of its derivatives with chlorine atoms. The kinetic behavior and the products of these reactions have been studied at 298? 2 K and 1 atm pressure using a technique to determine the relative rates of speed. The kinetic study has been carried out using a system with a static bag as Teflon reactor and GC-MS/FID as techniques for separation and detection of species. The study of products has been conducted in the absence of NOx using two different techniques. First, with the same experimental system that was used in the study kinetic but with the microextracción in solid phase (SPME) as a system of preconcentration. And secondly, using a foto-reactor quartz with in situ analysis with using a Fourier transform infrared (FTIR). The relationship of constant velocity for the reactions of atoms with Cl furan and its derivatives relating to nonane are: furan (0.41? 0.05); 2-metilfurano (0.85? 0.03); 3-metilfurano (0.88? 0.04): 2-etilfurano (0.95? 0.05); and 2,5-dimetilfurano (1.17? 0.06). Taking k (Cl + n-nonano) = (4.82? 0.14) x1010 cm3molécula-1s-1 constants obtained absolute speed (in units x1010 cm3molécula-1s-1) were: furan (2.0? 0.2); 2-metilfurano (4.1? 0.2); 3-metilfurano (4.2? 0.3); 2-etilfurano (4.6? 0.3) and 2,5-dimetilfurano (5.7? 0.3). The oxidation initiated by Cl furans leads to the formation of chlorinated compounds as furanonas chlorinated (for furan, 2-metilfurano, 3-metilfurano and 2-etilfurano) and acid chlorides (2-metilfurano, 2-etilfurano and 2.5 - dimetilfurano) as main products. In addition, there are compounds 1,4-dicarbonilicos unsaturated aldehydes and as formaldehyde, acetaldehyde, furfuraldehyde, 3-furaldehído, 5-metilfurfural, HCl and other products. This study shows that the removal of the hydrogen atom is small and the addendum to the double bond is the main way of reaction (> 90%). This study allowed for the detailed reaction mechanism of each of the selected furans, which are necessary for the construction of atmospheric models.

Author: GARCÍA-ARÁEZ GARCÍA DEL VALLE NURIA.
Year: 2006.
University: ALICANTE [www.ua.es].
Place of defense: FACULTAD DE CIENCIAS.
Place of preparation: UNIVERSIDAD DE ALICANTE.

Summary: The characterization of molecular-level structure and composition of the interface platinum / dissolution is a fundamental issue of great interest applied, given the high reactivity of platinum in many reactions of interest in technology, such as fuel cells. In this thesis takes place this characterization through an exhaustive analysis method based on the implementation of the equation electrocapilar. Based on the response of the interface (voltametría cyclical) depending on the concentration of a particular ion in solution, under conditions of constant ionic strength, it is possible to determine the size (surface concentration) of the specific ion adsorption in the study. This method was applied to the characterization of chloride, bromide, (bi) sulfate and hydrogen on Pt (111), can explain the behavior of these species by their different properties of adsorption. Under certain conditions, this analysis can be extended to the processes of adsorption no-específica. Due to the lesser magnitude of these útlimos, this study requires a precision and accuracy significantly higher than in the cases of specific adsorption. Moreover, analysis of the interfacial response depending on the temperature, based on the implementation of the equation electrocapilar, provides very important information on the status of species interfaciales. This analysis requires a combination of measures voltametría cyclical and potential total burden zero depending on the temperature, providing an estimate of the total entropy of adsorbed species. The extension of this analysis processes adsorption no-específica required the completion of a number of experiences excessive, and it is very difficult to meet the requirements of precision and accuracy. However, this study can be performed in a simple manner (at trial) through the technique of warming by nanosecond laser pulses. This technique allows us to separate the processes of adsorption no-específica of specific adsorption, since they have, in general, greater relaxation times. In short, all results presented in this thesis provides a fairly complete description of the interface platinum / dissolution

Author: VILLACAÑAS PÉREZ ÓSCAR.
Year: 2006.
University: BARCELONA [www.ub.es].
Place of preparation: UNIVERSITAT DE BARCELONA.

Summary: The inhibition of the cell cycle arises as a therapeutic strategy in treating diseases characterized by hiperproliferación cell, as in the case of cancer. The molecular modeling (including molecular mechanics, molecular dynamics, energy calculations free union, making farmacóforos, search for compounds in three-dimensional databases, tools Q3PR ..) has been used for this purpose. The first part of the work is seeking small molecules miméticas inhibitor tumors natural p16INK4a (p16). The protein p16 stops the cell cycle at the beginning of phase G1 inhibiting protein kinases dela family of CDK following. CDK4 and CDL6. Changes in the expression of p16 exist a large number of cancers, and the restoration of its role has been raised in this study as a strategy in cancer treatment. There have been farmacóforos that define the geometric characteristics of inhibitors CDL4 and CDK6 based on information extracted from dynamic simulations carried out in the complex natural CDL6-p16, CDK4-p16. CDK4-péptido and CDK6-péptido. The peptide, synthetic 20 amino acids, is Mimetic of p16. The genetic structure with the peptide complex has been modeled by sequence homology and molecular dynamics. The final structure of the peptide has been validated by calculation of the change in free energy union in a sweep of mutacional alanine on the peptide. One of the farmacóforos made was used to find molecules in the database Available Chemical Database, which were selected for comparison 10 compounds. The 40% of the compounds were purchased have an IC50 of less than 100 mcM compared to the kinase activity of CK6, were active compared with CDK4, inactive versus CDK1 and CDK2 and join in the same region of union that p16 in CDK6 . We anchorages molecules in CDK6, led by farmacóforo used, and through empirical functions (X-Score) was ordered correctly activity of the compounds. In the second part, have been studied ligands related to DNA. We have developed functions (tools QSPR), which estimated the parameters of propeller of homopentámeros polyamide, in a position isohelicoidales with B-AND. The functions serve to polyamides formed by both monomers levels as monomers which have a simple link between rings levels.

Author: GARÍCA ESCRIBANO PILAR.
Year: 2006.
University: COMPLUTENSE DE MADRID [www.ucm.es].
Place of defense: FACULTAD DE CIENCIAS QUÍMICAS.
Place of preparation: FACULTAD DE CIENCIAS QUÍMICAS.

Summary: Since the Industrial Revolution to today, the main energy sources have been exploited fossil fuels. But this model of development sooner rather than later lead to the depletion of fossil resources, without further with the kind of ecological concern that currently exists on the use of petroleum. Therefore there at the moment awareness globally to untie the progress of humankind from its dependence on oil by encouraging research into new energy sources to enhance that are more efficient and cleaner. It is in this context that appear in the fuel cells as generating clean electricity, generated almost exclusively since water as a byproduct of the reaction regardless of the fuel used, as well as presenting an alternative jurisdiction. Specifically, within fuel cells, the polymer membrane exchange protónico (PEM) before us, and that basically an assembly electrodo-membrana -electrodo (which is called MEA) gagged between two graphite bipolar plates , emerging primarily for use in mobile applications (electric vehicles) and portable devices. This paper aims at commissioning, synthesis and characterization of new polymeric materials, drivers protónicos and electronic application of fuel cells in exchange protónico, fueled by hydrogen or by direct methanol. First we approached the development of new materials to replace the graphite bipolar plate as fuel cell membrane exchange protónico. The graphite, but it is good conductor electronic, light and their tendency to corrosion under the conditions of operation of a PEMFC is low, it is a material expensive and difficult to machine. Therefore, it must synthesize polymeric composites having high electronic conductivity, good termomecánicas properties, and excellent chemistry, as well as low cost. To this end synthesizes an elastomer blends, etilen-propilen-norborneno (EPDM), which provides material that facilitates their elasticity model later, and a semi-crystalline thermoplastic polymer, polyethylene (PE), which contributes mainly to the stability CN provides excellent conductive properties to composites, and the SW, which has larger grains, facilitates the incorporation of CN to provide the mixture more fluently. To learn more about its properties and thus its potential for application in PEM cells, the materials obtained are characterized in terms of electrical and microstructural, subjecting them to test mechanical traction and understanding, and measure its severity, as well as analysis differential scanning calorimetry (DSC), also considering its crystallization kinetics not isotherm analysis mecano-dinámico (DMA) and the study of electrical conductivity DC. The rest of the work seeks to obtain high polymeric membranes driving protónica, technological properties suitable for its possible application in fuel cells exchange protónico: for which we are going to get, characterize, manufacture and compare three families of membranes based on the following polymeric materials, a terpolímero of etieleno-propileno-dieno (EPDM), a copolymer block butadieno-estireno hydrogenated (HSBS), and a third component, polypropylene (PP), polystyrene (PS) or silica, in two different proportions, 45/45/10 and 40/10/20, respectively. The materials will be synthesized and subjected to the curing reaction, to obtain a highly elastic material, and later sulphation heterogeneous properties to give drivers protónicas. All these materials, raw vulcanizados and sulphonated, will be subjected to a characterization microestrural, mechanical tensile testing, hardness and residual deformation analysis by differential scanning calorimetry (DSC), analysis mecano-dinámico (DMA) and analysis by infrared spectroscopy (ER), and the same m 8 ateriale 4b5 s sulphonated will also be subjected to a characterization of electrical impedance spectroscopy (EIS) and an analysis of diffusion of water and methanol to his through. Finally and as a decisive step towards implementation of any of the studied as electrolyte membranes in PEM cells, it is essential to determine the power density that are capable of developing in every case, as well as the characterization of the electrical properties of materials and their interfaces with electrodes. To do so, the relevant tests are performed for these materials and power density compared to the current density, as well as a study of modeling each monocelda by impedance spectroscopy technique to learn more about the processes taking place in their interior.