Grupos protectores fotocliváveis para aminoácidos e péptidos

Tese de mestrado em Química, especialização em Ensino.O objectivo primário deste trabalho consistiu na síntese de novos derivados de heterociclos de oxigénio, os ácidos nafto[2,1-b]furan-1-il etanóicos e os 1-clorometil-3- oxo-3H-benzo[f]benzopiranos e na sua aplicação a aminoácidos como modelos representativos de biomoléculas. Por reacção de acoplamento entre os ésteres metílicos de aminoácidos α e os ácidos nafto[2,1-b]furan-1-il etanóicos sintetizados foi possível obter derivados de aminoácidos fluorescentes marcados nos grupos amina das cadeias principal e lateral, e também no grupo hidroxilo da cadeia lateral. Investigou-se a estabilidade do fluoróforo da função amina em condições que são usadas frequentemente nas reacções de clivagem química em síntese peptídica. A derivatização de aminoácidos α, N-protegidos (benziloxicarbonilo e tosilo), com 1-clorometil-3-oxo-3H-benzo[f]benzopiranos originou derivados de aminoácidos fluorescentes marcados no C-terminus. Todos os compostos obtidos foram caracterizados pelas técnicas espectroscópicas habituais. Estudos de fluorescência dos heterociclos e dos derivados fluorescentes foram também efectuados. Com o objectivo final de investigar a possível aplicação dos 1-clorometil-3-oxo- 3H-benzo[f]benzopiranos como grupos protectores fotocliváveis, efectuaram-se estudos de fotólise (lâmpada de mercúrio de média pressão de 150 W) dos derivados fluorescentes de fenilalanina. Testes de estabilidade e de remoção química do marcador foram também efectuados.The first purpose of this work was the synthesis of new oxygen heterocyclic derivatives, naphtho[2,1-b]furan-1-yl ethanoic acids and 1-chloromethyl-3-oxo-3Hbenzo[f]benzopyrans, and their application to amino acids as representative models of biomolecules. It was possible to obtain fluorescent α-amino acids labelled at their amino N-terminus or at their amino or hydroxyl side-chain groups by coupling reaction between -amino acid methyl esters and naphtho[2,1-b]furan-1-yl ethanoic acids. The stability of these compounds under deprotection conditions usually used in peptide synthesis was evaluated. Derivatisation of N-protected (benzyloxycarbonyl and tosyl) α-amino acids with 1-chloromethyl-3-oxo-3H-benzo[f]benzopyrans gave fluorescent amino acid derivatives at their C-terminus. All compounds were fully characterised by the usual techniques and the fluorescence properties were also evaluated. The last objective of this work was to investigate the use of the 1-chloromethyl- 3-oxo-3H-benzo[f]benzopyrans as photocleavable protecting groups. Thus, photolysis studies (medium pressure mercury arc lamp of 150 W) with fluorescently labelled phenylalanine were carried out. Stability tests and chemical removal of the label were also done

Engine performance of a single cylinder direct injection diesel engine fuelled with blends of Jatropha Curcas oil and stardard diesel fuel

Blends of Jatropha Curcas oil and standard diesel fuel were evaluated (without pre-heating). The engine tests for the blends were performed in a Petter single cylinder direct injection diesel engine under steady state conditions at high loads. Engine speeds between 1300-1700 rpm were selected for the engine tests. Torque, power output, specific fuel consumption, in cylinder pressure, ignition delay, rate of heat released and exhaust composition were evaluated. The tested blends between 10-20% of oil shown lower effective torque and power output joint to a higher specific fuel consumption related to the lower heating value of Jatropha oil compared to diesel fuel. Lower pressure peaks and rates or pressure rises were observed when Jatropha blends are used. A decrease in the rate of heat released and shorter ignition delay were observed for the blends. Decreases in HC and CO emissions were observed for blends compared to diesel fuel. Both alternatives assessed shown that the differences observed compared to diesel fuel, can be partially restored with engines regulation. The use of Jatropha oil in order to be a partial or full alternative to the use of diesel fuel for energy production was achieved

Pedestrian forward projection after vehicle collision

This paper is focused in the assessment of the relation between the vehicle collision velocity, the pedestrian throw distance and the pedestrian injury, after vehicle–pedestrian collision with forward projection. A few parameters were considered, in particular the collision velocity (8), the pedestrian mass and height (8), and the mass of the vehicle (3). The results of the throw distance projection were compared using two solution methods (simple and advanced), the results of other authors and with 15 real data accident with forward projections. A total of 192 different conditions were simulated, being the results in good agreement. The injury of the pedestrian was calculated, based on two injury criteria (GSI and FFC), aiming to define a simple relation between pedestrian injury and the vehicle collision velocity.info:eu-repo/semantics/publishedVersio

Fire protection efficiency of intumescent coatings

This paper presents an experimental study about the fire protection efficiency of a material produced of an emulsion of intumescent coating with granulated cork. The analysis is performed at the micro scale level, with TG and DSC tests at elevated temperatures, and in a mass loss calorimeter with protected steel plates, with temperatures representative of a fire scenario. The results indicate that an increased protection is obtained when the granular cork particle size is smaller and a cork mass fraction of 5% is used.info:eu-repo/semantics/publishedVersio

Synthesis and spectral characterization of a fluorescent marker

A fluorescent naphtofuran was synthetized from benzopyran by alcaline ring contraction and coupled to the α-amine group of various amino acids, in order to evaluate its applicability as a fluorescent marker for biomolecules. Fluorescence data was collected for all derivatives.Fundação para a Ciência e Tecnologia

A naphtho[2,1-b]furan as a new fluorescent label: synthesis and spectral characterisation

A fluorescent naphthofuran was synthesised from an oxobenzopyran by alkaline ring contraction and coupled with various L-amino acids at their N-terminus or at side-chain functional groups, in order to evaluate its applicability as a fluorescent label for biomolecules and in peptide synthesis. Fluorescence data were collected for all derivatives, which were found to be moderately fluorescent and having moderate to good fluorescence quantum yields.Thanks are due to the Foundation for Science and Technology (Portugal) for financial support through Centro de Química (UM)

Thermomechanical analysis of cold formed steel sections

This work presents an experimental study about cold formed steel elements submitted to compression loads. The sections analyzed are C and Z sections made of steel sheet with 1.5 and 2 [mm] thick and three different cross section heights. The compression tests were made at ambient and elevated temperatures. In both cases a pined support was developed and used. The member resistance at ambient temperature was determined by applying an increasing compression load until the member collapse was achieved. The fire tests were performed in a fire resistance furnace, using the same type of end supports, and a mechanical load given by a specific degree of utilization that is maintained constant during the fire test. These tests allow the determination of the fire resistance time and member critical temperature. The experimental results are compared with the ones obtained with the Eurocode simplified models.info:eu-repo/semantics/publishedVersio

Thermomechanical analysis of cold formed steel sections

This work presents an experimental study about cold formed steel elements submitted to compression loads. The sections analyzed are C and Z sections made of steel sheet with 1.5 and 2 [mm] thick and three different cross section heights. The compression tests were made at ambient and elevated temperatures. In both cases a pined support was developed and used. The member resistance at ambient temperature was determined by applying an increasing compression load until the member collapse was achieved. The fire tests were performed in a fire resistance furnace, using the same type of end supports, and a mechanical load given by a specific degree of utilization that is maintained constant during the fire test. These tests allow the determination of the fire resistance time and member critical temperature. The experimental results are compared with the ones obtained with the Eurocode simplified models.info:eu-repo/semantics/publishedVersio

Thermal behaviour of rebars and steel deck components of composite slabs under natural fire

Most of the studies involving composite slabs under fire follow the standard fire scenario described by the ISO 834 curve, disregarding the cooling-phase. However, recent studies show that this phase is equally important, as it can lead to the collapse of the structure. Therefore, the present research carried out a parametric study, using numerical models, validated through experimental tests, to evaluate the thermal behaviour of the composite slabs components under natural fire. The results showed that the maximum temperatures in the reinforcement bars occur during the cooling-phase, reaching temperatures up to 300% higher than at the heating-phase, on the steel deck occur at the end of heating, and that the concrete thickness above the steel deck influences the temperature of these components. Also, during the cooling-phase, a “heat bubble” effect is observed on the ribs of the composite slabs, where the reinforcement bars are normally placed. These results highlight the importance of considering different natural fire scenarios, in the structural performance and safety of composite slabs, since during the cooling-phase there is still heat transfer between the elements, which can lead to slab failure. New parameters are proposed to find the temperature of each component for different fire ratings

Acridinyl methyl esters as photoactive precursors in the release of neurotransmitter amino acids

An investigation of the use of an azaheterocycle, acridine, as an alternative photochemically removable protecting group for the carboxylic function of neurotransmitter amino acids was carried out. 9-Bromomethylacridine was used in the reaction with glycine, alanine, glutamic acid, β-alanine and γ-aminobutyric acid, to obtain model ester derivatives, which were irradiated at different wavelengths in a photochemical reactor. The process was followed by HPLC/UV, resulting in the release of the active molecule in short irradiation times. The results obtained using 419 nm irradiation show promise (35-98 min) for practical purposes. The compounds were further characterised via time-resolved fluorescence to elucidate their photophysical properties and determine the decay kinetics.Fundação para a Ciência e Tecnologia (FCT, Portugal) for financial support to the NMR portuguese network (PTNMR, Bruker Avance III 400-Univ. Minho), FCT and FEDER (European Fund for Regional Development)-COMPETE-QREN-EU for financial support to the research centre CQ/UM [PEst-C/QUI/UI0686/2011 (FCOMP-01-0124-FEDER-022716)] and project PTDC/QUI/69607/2006 (FCOMP-01-0124-FEDER-007449). FCT - a PhD grant to A.M.P. (SFRH/BD/61459/2009)