962 resultados para proton affinities


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Karst fillings rich in fossils from carbonate series, Miocene in age, exposed on the coast of Algarve, yielded some thousands of teeth and other vertebrate remains. A crocodilian and more than fifty species of fishes (Selacians, Teleosteans) have been identified (see tableau 1). This fauna is consistent as a whole with a Burdigalian (maybe late) and/or Langhian age. It also indicates shallow waters, warmer than at present in the same region although not strictly tropical. This fauna shows more affinities with others of the same age from mediterranean region (i.e. Baleares) than with those from Lisbon.

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Small mammals from a water well near Morgadinho indicate an age comprised between Middle Villafranchian, MN 17 zone and lowermost Middle Pleistocene, MN 20. This fauna corresponds to an humid region under a possibly temperate (certainly not cool) climate. Nearly all Gastropoda have quaternary affinities. Most are freshwater dwellers. Ostracoda lived in lacustrine or extensive swamp enviromnents rich in plants. They also point out to fresh waters (eventually oligohaline; this may suggest some kind of communication with the sea, which would not be very close by), and to water temperatures over 10.5°C. Charophyta thrive in fresh, carbonate-rich waters. Cyprinid fishes are also freshwater dwellers, and amphibians exclude any significant salinity. Palynological analysis shows climate should be warm and rather humid. Near Morgadinho there was a mixte mesophytic forest (and perhaps a sempervirent, large leave type forest at Algoz). Morgadinho and Algoz (this locality being dated MN 20, lowermost Middle Pleistocene) are probably correlative, and this may also be true for lacustrine limestones at Ponte das Lavadeiras, near Faro.

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The littoral and the «barrocal» of the Algarve correspond in part to a meso-cenozoic sedimentary basin with a deeping south monocline structure, cut by North-South faults and by two East-West longitudinal flexures. The lithostratigraphic and chronostratigraphic study of the Jurassic formations, undertaken during the last years, allow a better knowledge of the paleogeographic and paleobiogeographic evolution of these formations and particularly of the Callovian-Kimmeridgian. Lower Callovian facies, being similar from Sagres in the West to beyond Tavira, show the uniformity of the sedimentary conditions. Since Middle Callovian, the beginning of the regressive cycle is responsible for a major unconformity between Dogger and Malm. During the Lower Oxfordian a new sedimentary cycle begins with a transgression afecting the region south of the Albufeira-São Brás de Alportel-Tavira line thus originating a gulf centered in the Loulé area which rapidly diminishes since the Lower Kimmeridgian. The faunistic affinities are always tipically tethyan although some classic boreal fauna exist, in contrast with the Northern Tagus basin (where affinities are sub-boreal during the Callovian).

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Beaver only had been found in Portugal in a Chalcolithic locality, the Vila Nova de S. Pedro castrum. It has now been identified in the Upper Paleolithic (Solutrean) from Gruta do Caldeirão, near Tomar. The species has been found recently at «Gruta do Almonda»; 4 teeth were collected in bed C, older than a Solutrean sequence (see Anexo for details). The species seems to have been rare, as it was also the case with portuguese Miocene Castoridae Enroxenomys minutus and Chalicomys jaegeri. If account is taken of the presence in the Middle Ages until Castille of words meaning beaver (relared to the popular latin Fiber/Biber), it is obvious that these animais still existed then. Such nouns were largely predominant over rhe rather erudite latin (greek deríved) words as Castor,-óris and derived ones, as it could be expected. This allowed us to recognize that veiro should be the corresponding word with Fiber affinities in archaic portuguese. It was previously supposed to mean only expensive furs then imported into Portugal. Indeed it was also a zoonym. Anywày, beaver should be scarce by XIIIth century since it is not included in the quite detailed price list imposed by the «Lei da Almotaçaria» from December 26, 1253 (see Quadro II). Toponyms in veiro and derived words (fig. 2; Quadro III) (plural, feminines, diminutives, inhabited places) give a resrrictive view of rhe Middle Age distribution. Some of them are certainly older than Portugal itself (firsr half of XIlth cenrury); others existed by the XIVth century bur were probably older. Some rare toponyms seem to be derived from the erudite latin Castor,-óris. Nothing suggests that these words were still in use as zoonyms during the Middle Ages. All toponyms are located in regions near rivers and other freshwaters ecologically suitable for beavers, so we can approximately retrace its former, Middle Age disrribution in Portugal (fig. 2; Quadro III). Most of them are locared in the Center-West and Northwest of Portugal, with a suitable c1imate (rainfall in general over 800 mílimerers per year); the only sure geographical exception is Veiros, in Alto Alentejo province, in a region with comparable precipitations and less dry climate conditions than mosr of the territories South of rhe Tagus. There are less and less of these toponyms towards rhe South and the inner part of the country, and they are enrirely lacking in all drier regions from Trás-os-Montes, Beira, Alentejo beyond Tagus' basin, and in Algarve. Nothing suggests beavers lived there, No post-medieval toponym is known, nor any reference after middle XVth century. No such locality was at, or close by to, any frontier. Hence the hypothesis of veiro (et al.} as meaning but points where expensive furs (supposedly known as veiros in general but without c1early saying from what animal they were obrained from) is to be discarded. During the Middle Ages, beaver discriburion concerned all the main river basins from Minho to Tagus ones. Quite rarefied in rhe XIIIth, the beavers may have disappeared from Portugal during the XVth century. Ecological requiremenrs restricted their former distriburion. Vulnerability to natural causes (i.e., severe drought) and to human pressure may have accounted heavily for this species' extinction. Last (1446) reference for Portugal known to us suggests the species was by then almost extinct.

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The chemical and mineralogical charactetistics of the intrusive and extrusive rocks of this igneous complex are presented. The suggest affinities between these rocks. The major and the trace elements lead us to conclude that these rocks were originated in a common magmatic chamber by fractional crystallization.

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Mestrado em Radioterapia - Área de especialização: Dosimetria Clínica

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We look for minimal chiral sets of fermions beyond the standard model that are anomaly free and, simultaneously, vectorlike particles with respect to color SU(3) and electromagnetic U(1). We then study whether the addition of such particles to the standard model particle content allows for the unification of gauge couplings at a high energy scale, above 5.0 x 10(15) GeV so as to be safely consistent with proton decay bounds. The possibility to have unification at the string scale is also considered. Inspired in grand unified theories, we also search for minimal chiral fermion sets that belong to SU(5) multiplets, restricted to representations up to dimension 50. It is shown that, in various cases, it is possible to achieve gauge unification provided that some of the extra fermions decouple at relatively high intermediate scales.

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Treatment of a dichloromethane solution of trans-[Mo(NCN){NCNC(O)R}(dppe)(2)]Cl [R = Me (1a), Et (1b)] (dppe = Ph2PCH2CH2PPh2) with HBF4, [Et3O][BF4] or EtC(O)Cl gives trans-[Mo(NCN)Cl-(dppe)(2)]X [X = BF4 (2a) or Cl (2b)] and the corresponding acylcyanamides NCN(R')C(O)Et (R' = H, Et or C(O)Et). X-ray diffraction analysis of 2a (X = BF4) reveals a multiple-bond coordination of the cyanoimide ligand. Compounds 1 convert to the bis(cyanoimide) trans-[Mo(NCN)(2)(dppe)(2)] complex upon reaction with an excess of NaOMe (with formation of the respective ester). In an aprotic medium and at a Pt electrode, compounds 1 (R = Me, Et or Ph) undergo a cathodically induced isomerization. Full quantitative kinetic analysis of the voltammetric behaviour is presented and allows the determination of the first-order rate constants and the equilibrium constant of the trans to cis isomerization reaction. The mechanisms of electrophilic addition (protonation) to complexes 1 and the precursor trans[Mo(NCN)(2)(dppe)(2)], as well as the electronic structures, nature of the coordination bonds and electrochemical behaviour of these species are investigated in detail by theoretical methods which indicate that the most probable sites of the proton attack are the oxygen atom of the acyl group and the terminal nitrogen atom, respectively.

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New sensory materials based on p-phenylene ethynylene trimers integrating calix[4]arene receptors (CALIX-PET) and tert-butylphenol (TBP-PET) moieties have been synthesized and their sensitivity and selectivity for the detection of nitroaromatic compounds (NACs) such as nitrobenzene (NB), 2,4-dinitrotoluene (2,4-DNT), 2,4,6-trinitrotoluene (TNT) and picric acid (PA) investigated in fluid phase and solid-state. It was found that both fluorophores displayed high sensitivities toward NACs detection in solution as evaluated by the Stern-Volmer formalism. For all the tested explosives, the ratio of fluorescence intensities (F-0/F) is a linear function of the quencher concentration only after appropriate correction of fluorescence quenching data for inner-filter effects. The quenching efficiencies for CALIX-PET and TBP-PET follow the order PA >> TNT > DNT > NB, which correlate well with the quenchers electron affinities as evaluated from their LUMOs energies thereby suggesting a photoinduced electron transfer as the dominant mechanism of fluorescence quenching. The selectivity of these sensors was checked against exemplar interferents possessing differentiated electronic properties (benzoic acid, 2,4-dichlorophenol and benzoquinone) and reduced quenching activity was detected. The quenching efficiencies and response times of the two fluorophores in the solid-state toward NB, 2,4-DNT and TNT vapors were evaluated through steady-state fluorescence quenching experiments with the materials dispersed in polymeric matrices or as neat films. The most significant fluorescence quenching responses were achieved for drop-casted films of TBP-PET upon exposure to nitroaromatics.

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Journal of Human Evolution, V. 55, pp. 148-163

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FEMS Yeast Research, Vol. 9, nº 4

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Dissertação apresentada para obtenção do Grau de Doutor em Engenharia Química, especialidade de Operações Unitárias e Fenómenos de Transferência, pela Universidade Nova de Lisboa, Faculdade de Ciências e Tecnologia

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Trabalho Final de Mestrado para obtenção do grau de Mestre em Engenharia Química e Biológica

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Journal of Bacteriology (Out 2010) 5312-5318