Aquacultura multi-trófica integrada em tanques de terra

Mestrado em Engenharia Zootécnica - Produção Animal - Instituto Superior de Agronomia / Faculdade de Medicina Veterinária - ULEste trabalho teve como objetivo avaliar a produção em policultura de três sistemas multi-tróficos integrados em tanques de terra no concelho de Olhão, Parque Natural da Ria Formosa: S1 (peixes, ostras com macroalgas), S2 (peixes com ostras) e S3 (peixes com macroalgas) com as espécies de peixes corvinas (Argyrosomus regius) sargos (Diplodus sargus) e tainhas (Mugil cephalus), ostras (Crassostrea gigas) e macroalgas (Ulva spp.) utilizando principalmente como parâmetros a Taxa de Crescimento Específica (TCE) e a Taxa de Conversão Alimentar (TCA) de modo a averiguar o sistema mais eficiente para posteriormente calcular a sua rentabilidade. As corvinas de S2 apresentaram melhores pesos médios (366,5 ± 83,3 g) do que S1 e S3. No entanto, S1 apresentou um menor valor de TCA = 1,76 sendo mais eficiente do que S2 com TCA = 1,90 e S3 com TCA = 2,42. A sua TCE para S1 e S2 foi de 0,40% e para S3 foi de 0,31%. No caso dos sargos e tainhas, por questões de maneio e de bem-estar animal, os seus parâmetros de crescimento foram previstos e extrapolados. As ostras, em 93 dias de cultivo, apresentaram melhores TCE em S1 (4,06%/dia) do que em S2 (3,53%/dia) mas a sua sobrevivência foi baixa. A TCE da Ulva, colocada em estruturas flutuantes divididas em seis compartimentos, três deles com altas densidades de Ulva e outros três com baixas densidades, foi melhor em S3 do que em S1, e melhor em compartimentos de baixa densidade do que em compartimentos de altas densidades. A nova biomassa de Ulva produzida em 8 semanas nos tanques atingiu os 9,36 kg em S1 e os 10,24 kg em S3. Uma extrapolação foi feita com os resultados obtidos neste trabalho e com base em outros ensaios, verificando-se que o sistema integrado é viavelmente económicoN/

The 9-Anthroate chromophore as a fluorescent probe for water

Water quenches the fluorescence of methyl 9-anthroate with a rate constant showing little dependence on solvent viscosity or polarity. In dioxane, at 20ºC the value of the rate constant is 9.6 X 10^6 M^(-1) s^(-1) , and the activation energy found for the process is 14.1 kJ mol^(-1). The quenching process is entropy-controlled and is likely to involve a hydrogen-bonded complex as an intermediate. Since the fluorescence lifetime of methyl 9-anthroate does not depend on the solvent properties other than its hydrogen-bonding ability, the concentration of nearby water can be estimated directly. Values of 3, 54, and 14 M were obtained for the solubilization site of methyl 9-anthroate in micelles of Triton X-100, sodium dodecyl sulfate (SDS), and dodecyltrimethylammonium chloride (DTAC), respectively. From the ring current effect of the anthroate group on the 'H NMR chemical shifts of the surfactant protons, it is concluded that the anthroate fluorescent probe is preferentially located in the surface region of the SDS and DTAC micelles; however, in Triton X-100, it resides in the micelle interior near the phenoxy groups of the surfactant molecule

Kinetics and thermodynamics of poly (9,9-dioctylfluorene) beta-phase formation in dilute solution

Poly(9,9-dioctylfluorene) (PFO) adopts a particular type of conformation in dilute solutions of the poor solvent methylcyclohexane (MCH) below 273 K, which is revealed by the appearance of a red-shifted absorption peak at 437−438 nm. The formation of this ordered conformation depends on the temperature but is independent of polymer concentration over the range studied (3−25 μg/mL). On the basis of absorption, steady-state, and time-resolved fluorescence data, the new absorption peak at 437−438 nm is assigned to a highly ordered conformation of PFO chains, analogous to the so-called β-phase first identified in PFO films. From the study of PFO solutions in MCH as a function of temperature, we conclude that these ordered segments (β-conformation) coexist with less ordered domains in the same chain. When the ordered domains are present, they act as efficient energy traps and the fluorescence from the disordered regions is quenched. The transition between the disordered and the ordered PFO conformations is adequately described by a mechanism that involves two steps:  a first, essentially intramolecular, one from a relatively disordered (α) to an ordered conformation (β), followed by aggregation of chains containing β-conformation into anisotropic ordered domains. From the temperature dependence of the 437−438 nm peak intensity, the transition temperature Tβ = 261 K, enthalpy ΔHβ = −18.0 kcal mol-1, and entropy ΔSβ = −68.4 cal K-1 mol-1 were obtained. The formation of the β-conformation domains were also followed as a function of time at 260 K. The rate constants at 260 K were determined, showing an order of magnitude around 10-3 s-1 (kα→β = 5.9 × 10-4 s-1; kβ→α = 9 × 10-4 s-1; kagg = 2.3 × 10-3 M-1 s-1; kdiss = 4.4 × 10-4 s-1). This small magnitude explains the long times required for a “complete” conversion to the β-conformation

β-Carbolines. 2. Rate Constants of Proton Transfer from Multiexponential Decays in the Lowest Singlet Excited State of Harmine in Water As a Function of pH

The β-carbolines present a complex problem involving multiple equilibria in the excited state in hydrogen-bonding solvents including water. Three excited state species exist: neutral, cation, and zwitterion. Here we examine the multiple equilibria and excited state kinetics of harmine, using time-resolved and steady state fluorescence techniques. From an analysis of the multiexponential decays, measured at the emission wavelengths of the three species as a function of the pH, seven unknowns (four rate constants and three reciprocal lifetimes) were determined. Data analysis was made both by a previously reported numerical method and by analytical solution of the differential equation set. The results obtained accurately describe the independently obtained steady-state fluorescence results. The dramatic modifications of the equilibria and rate constants between the ground and excited states can be understood on the basis of the significative changes in charge densities on the two nitrogen atoms of harmine upon excitation. Mechanisms are proposed for the formation of excited state cation and zwitterion beginning with the excited state neutral molecule

9-Borafluoren-9-yl and diphenylboron tetracoordinate complexes of 8-quinolinolato ligands with heavy-atoms substituents: synthesis, fluorescence and application in OLED devices

This work describes the synthesis and characterisation of new tetrahedral boron complexes, incorporating bromine- or iodine-substituted 8-quinolinolato chelate chromophores connected to 9-borafluoren-9-yl or diphenylboron orthogonal fragments. The molecular features and photophysical properties of these complexes are analysed in both solution and solid state. Steady-state photophysical studies reveal photoluminescence quantum yields (Φf) ranging from 0.02 to 0.15 and prompt fluorescence (PF) lifetimes (τf) between 2 and 16 ns. Time-resolved photophysical experiments show the presence of delayed fluorescence (DF) and phosphorescence at both 77 K and room temperature. The DF intensity increases with a rise in temperature. This variation is ascribed to an enhancement in the intersystem crossing (ISC) process promoted by the bromine or iodine heavy-atom effect. Investigations into the dependence of DF intensity relative to the excitation dose indicate emissions stemming either from Triplet-Triplet Annihilation (TTA), Thermally Activated Delayed Fluorescence (TADF), or a combination of these competing mechanisms. The effect is related to the size and number of heavy-atom substituents in each boron complex. A study of the DF emission intensity as a function of the excitation dose reveals that diiodo-substituted 8-quinolinolato boron complexes, whether rigid or flexible, display TADF emission. Rigid 5,7-dibromo- and 5-chloro-7-iodo-substituted 8-quinolinolato complexes exhibit a combined TADF-TTA mechanism, whereas the other complexes predominantly demonstrate pure TTA emission. DFT and TDDFT calculations showed that the ground state structures reproduced the experimental geometries and only small increases in bond lengths were observed in the excited state geometries. The low energy absorption bands displayed mainly intra-ligand π→π* (8-quinolinato) character. The fluorescence emission energies were well reproduced, while the singlet-triplet energy gaps were relatively high. Ultimately, organic light-emitting diodes (OLEDs) are fabricated using the most luminescent boron complexes. The best OLED is obtained when using complex 3a, which displays green electroluminescence (EL) (λEL = 502 nm) with maximum external quantum efficiency (EQEmax) of 2.5% and maximum luminance (Lmax) of 2200 cd m-2

Transiciones térmicas en recubrimientos polisiloxánicos de fibras de vidrio

Se realizó una estimación de las temperaturas de relajación de recubrimientos poliméricos en fibras de vidrio. Para ello, se llevó a cabo el seguimiento de la respuesta fluorescente, en función de la temperatura, de dos fluoróforos químicamente enlazados al recubrimiento polimérico. Las fibras de vidrio fueron tratadas con una disolución acuosa de 3-aminopropiltrietoxisilano(APES), y una mezcla al 50 % de APES y de 3-aminopropilmetildietoxisilano (APDES). Los marcadores fluorescentes, cloruro de pireno-1-sulfonilo (PSC) y cloruro de 1-dimetilamino-5-naftalenosulfonilo (DNS), se anclaron a las fibras de vidrio silanizadas a través de la formación de un compuesto sulfonamida estable y fluorescente (PSA y DNSA respectivamente).Se realizaron sus espectros de emisión en función de la temperatura en el intervalo (133, 413)K. Los resultados mostraron transiciones térmicas a bajas temperaturas para las muestras estudiadas indicando la alta flexibilidad de la región de acoplamiento. Además, dicha temperatura de transición depende de forma clara de la estructura del polímero que recubre a las fibras.It was estimated the relaxation temperatures of polymeric coatings on glass fibers. In order to do this, it was carried out the fluorescent response study, as a function of temperature, of two dyes chemically bonded to the polymeric coating. The glass fibers were treated with aqueous solutions of 3-aminopropyltriethoxisilane (APES) and a 50 % mixture of APES and 3-aminopropylmethyldiethoxisilane (APDES). The fluorescent labels, pyrene-1-sulfonyl chloride (PSC) and 1-dimethylamino-5- naphtalenesulfonyl chloride (DNS), were attached to the silanized glass fibers by the formation of a stable and highly fluorescent sulfonamide conjugate (PSA and DNSA respectively). Emission spectra were recorded as a function of temperature in the range (133, 413)K. The results shown thermal transitions at low temperatures, which reflect the high flexibility of the coupling region. In addition, that transition temperature clearly depends on the structure of the polymeric coating of the glass fibers

9-Borafluoren-9-yl and diphenylboron tetracoordinate complexes of F- and Cl-substituted 8-quinolinolato ligands: synthesis, molecular and electronic structures, fluorescence and application in OLED devices

Six new four-coordinate tetrahedral boron complexes, containing 9-borafluoren-9-yl and diphenylboron cores attached to orthogonal fluorine- and chlorine-substituted 8-quinolinolato ligand chromophores, have been synthesised, characterised, and applied as emitters in organic light-emitting diodes (OLEDs). An extensive steady-state and time-resolved photophysical study, in solution and in the solid state, resulted in the first-time report of delayed fluorescence (DF) in solid films of 8-quinolinolato boron complexes. The DF intensity dependence on excitation dose suggests that this emission originates from triplet–triplet annihilation (TTA). Density functional theory (DFT) and time-dependent density functional theory (TDDFT) studies give insight into the ground and excited state geometries, electronic structures, absorption energies, and singlet–triplet gaps in these new organoboron luminophores. Finally, given their highly luminescent behaviour, organic light-emitting diode (OLED) devices were produced using the synthesised organoboron compounds as emissive fluorescent dopants. The best OLED displays green-blue (λmaxEL = 489 nm) electroluminescence with an external quantum efficiency (EQE) of 3.3% and a maximum luminance of 6300 cd m−2

Photophysical Behavior of Coumarins as a Function of Substitution and Solvent: Experimental Evidence for the Existence of a Lowest Lying 1(n,.pi.*) State

The nature of the lowest excited state for coumarin and some derivatives was investigated using steady-state and time-resolved fluorescence data at room temperature, as well as fluorescence anisotropy at 77 Kin nonpolar and polar solvents in conjunction with theoretical data obtained with different methods: INDO/S-CI, CNDO/ S-CI, MNDO-CI, and AM1-CI. Theresultsshow that SI isactually n,?r* for coumarininanysolvent. Substitution with methoxy and methyl and/or chlorine and/or the increase of solvent polarity reduces the energy gap between the SI (n,**) and S2 (?r,?r*) states, promoting the mixing of these states and finally inducing inversion to SI (r,**) with trisubstitution and for the disubstituted case in dioxane:water (1:4). The presence of a lowest lying SI (n,a*) mediates a large degree of radiationless processes in the singlet mannifold

Effective distances of exothermic charge-transfer reactions in the excited state

A study of intermolecular, exothermic charge-transfer interactions is described. A distance dependence on the unimolecular charge-transfer rate constant k,,(R) is observed in viscous solvents where transfer at longer distances than the collisional one can compete with dissociation of an encounter complex. A comparative study of the quenching phenomena, occurring in a family of redox partners of aromatic esters and amines, was carried out in nonviscous solvents (hexane and acetonitrile) and viscous solvents (liquid paraffin/heptane mixtures and nonionic micelles of Triton X- 100). In the latter, the experimental reactional distances obtained are discussed in terms of effective distances R,ff, which are related to an average value of kct(Reff) for the reactant pair distribution function. A correlation of these distances with either the free activation energy, Act, or the diffusion coefficient D enables the estimation of an order of magnitude of parameters such as the average radii of donor and acceptor orbitals, L = (2.7 f 0.2) X cm, a preexponential factor at the collisional distance, k’,,(R,) = 3.7 X 10” d, an intrinsic reorganization parameter X = 0.64 eV, and an electronic matrix element V(Rc) N eV for the nonpolar media studied. An equation for kct(R), k,,(R) = koct(R,)e xp[-2(R - R,)/L] exp(-AG*/kB7+),d erived within the framework of a semiclassical theory, is used to discuss these interactions as equally nonadiabatic reactions to which an extended Marcus formalism is applied